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Effect of Parity Number and production Systems on Chemical
Composition of Cow Milk, Kenana Area, Sudan
Asma Abdelbagi Elhaj Ahmmed
B.Sc. (Honors) in Animal Production, Faculty of Animal Production,
University of Gezira (2004)
A Dissertation Submitted to the University of Gezira in Partial
Fulfillment of the Requirements for the Award of the Degree of Master
of Milk Production and Technology
in
Department of Milk Production and Technology
Faculty of Animal production
January, 2018
2
Effect of Parity Number and production Systems on Chemical
Composition of Cow Milk, Kenana Area, Sudan
By
Asma Abdelbagi Elhaj Ahmmed
Supervision Committee:
Name Position Signature
Dr. Asma Ali Tameem Eldar Main Supervisor ……………...
Dr. Ali Fadl Elmolla Khalid Co-supervisor
...…………...
Date:11/January/2018
3
Effect of Parity Number and production Systems on Chemical
Composition of Cow Milk, Kenana Area, Sudan
By
Asma Abdelbagi Elhaj Ahmmed
Examination Committee:
Name Position Signature
Dr. Asma Ali Tameem Eldar Chair Person ….…………...
Dr. Rania Hassan Zayed Isa External Examiner
………………...
Dr. Faiza Abubakr Omer Internal Examiner
…………………
Date of examination:11/January/2018
4
DEDICATION
To the soul my dear father
To my Mother
To my brothers and my sisters
To my husband and to my Children
To my friends
I dedicate this work, with sincere pleasure and respect
5
ACKNOWLEDGMENTS
I would like to express my sincere thankfulness to my research
Supervisors, Dr Asma AliTameem eldar and Dr. Ali Fadalmolla
Khalid , whose invaluable availability, constant academic
guidance and support have made this research endeavour fruitful.
I would also like to acknowledge of kenana farm employees for
providing the necessary administrative support and facilitating the
collection of sample without which all the efforts would have been
futile. I am highly indebted to my husband for his encouragement
and sacrifices to make all this possible
I sincerely thank all other people who, in one way or another,
supported my research. Special thanks go to my late father, for the
value of education he instilled in me. I cannot express more my
appreciation to my overly caring mother and my loving and
generous brothers and sister. Their emotional support kept me
going. I also acknowledge all my friends and colleagues for their
help interest and moral support to attain success.
Above all, this achievement would not have been materialized
without the abounding gifts of life, peace, health and guidance
under the unconditional and miraculous love and mercy of our
Lord God. To Thee, my Lord, be all glory and praises!
6
Effect of Parity Number and Production Systems on Chemical
Composition of Cow Milk, Kenana Area , Sudan
Asma Abdelbagi Elhaj Ahmmed
Abstract
The study was carried out to assess and compare the chemical composition of cow milk
produced from cow under traditional and intensive system for different parity number
(First parity, Third and Fifth). Milk samples (n = 18) were obtained from the two
production systems (nine milk samples of each) and were allocated, relative to parity
(3/parity) .The results of the study showed that parity significantly (p < 0.05) affected the
fat and total solid compositions. Highest values of fat (4.15) and total solid (12.75) were
recorded at first parity, while the lowest values observed in cow at fifth parity. Fat and
total solid percent decreased with advanced parities. There was no significant (p < 0.05)
difference among parity for solid non fat, protein and lactose. The highest values of these
components were obtained at third parity. The result indicated that production system
had affected significantly all milk components except milk fat. In intensive system fat
percent (3.26) recorded the highest value. The highest values of total solid, solid non fat,
protein and lactose were recorded in traditional system. The result showed that the cow in
fifth parity reported lowest value for all milk components in both production systems.
The result also authenticated that the highest quality milk was obtained in the third parity.
The study indicated that the variations in cow milk composition were mainly attributed to
factors such as parity order and production system. Therefore, those factors should be
taken into account when nutritional and technological aspects of cow milk are evaluated.
7
ينانةمنطاة ف ناا لى الاريي اليييياى لىن الاقاار الاتأثير رقم الولادة ونظام
الحا احيذ أسياء لنذالناق
الذراسةمىخص
وًظاهً الاًخاج علً الخشكيب الكيويائً للبي الابقاس. خوعج عيٌاث اخشيج هزٍ الذساست لوعشفت حأثيش سقن الىلادة
هي كل(، وقسوج الً ثلاثت اثعيٌ 9للخحليل الكيويائً لٌظاهً الاًخاج الخقليذي والوكثف )بىاقع بقشة 81اللبي هي
ابقاس فً كل هدوىعت هي الىلذة الاولً ، الىلذة الثالثت والىلذة 3هدوىعاث هخساويت علً حسب سقن الىلادة ، بعذد
اظهشث الٌخائح وخىد فشوقاث هعٌىيت لشقن الىلادة علً الذهي والدىاهذ الكليت . اعلً قيوت للذهي .الخاهست
، بيٌوا اقل ًسبت سدلج للابقاس فً الىلذة ولًسدلج للابقاس فً الىلذة الا (12.75)ت والدىاهذ الكلي (4.15)كاًج
اها الوكىًاث الاخشي هثل الدىاهذ غيش الذهٌيت، الخاهست ، وحقل ًسبت الذهي والدىاهذ الكليت بخقذم سقن الىلادة.
اكذث الٌخائح وخىد فشوقاث الىلذة الثالثت. ، اعلً قين لهزٍ الوكىًاث فً البشوحيي واللاكخىص لن حظهش فشوقاث هعٌىيت
هعٌىيت لٌظاهً الاًخاج علً خويع هكىًاث اللبي هاعذا دهي اللبي، اعلً قيوت لذهي اللبي سدلج فً الٌظام الوكثف ،
بيٌوا اعلً قيوت للوكىًاث الاخشي هثل الدىاهذ الكليت ، الدىاهذ غيش الذهٌيت ، البشوحيي واللاكخىص سدلج للٌظام
أعلً قيوت للذهي والدىاهذ الكليت سدلج للابقاس فً الىلذة الاولً فً الٌظام الوكثف ، بيٌوا اعلً قيوت خقليذيال
لوكىًاث اللبي الاخشي سدلج للابقاس فً الىلذة الثالثت للٌظام الخقليذي . اوضحج الٌخائح اى اقل ًسبت لكل هكىًاث
الٌخائح اثبخج اى الابقاس الخً فً الىلذة . لاًخاج الخقليذي والوكثفاللبي سدلج للابقاس فً الىلذة الخاهست لٌظاهً ا
بيٌج الذساست اى الاخخلاف فً هكىًاث اللبي يشخع الً عذة عىاهل هثل سقن الثالثت ححخىي علً اللبي الاخىد..
تًب الخكٌىلىخيالىلادة وًظن الاًخاج . وبٌاء علً رلك يدب اى حىضع هزٍ العىاهل فً الاعخباس عٌذ حقيين الدىا
.والغزائيت للبي الابقاس
.
8
LIST OF CONTENTS
Item Page
Dedication I
Acknowledgments II
English abstract III
Arabic abstract IV
Table of contents V
List of table VIII
List of figures IX
CHAPTER ONE 1
1. Introduction 1
CHAPTER TWO 3
LITERATURE REVIEW 3
2.1. Sudan Livestock resources 3
2.2. Cattles domestication 4
2.3. Cattle breeds in the Sudan 4
2.3.1. Kenana breed 5
2.3.2.Butana breed 6
2.3.3.Baggara breed 6
2.3.4.Cross breed in Sudan 7
2.4. Cattle milk 7
2.4.1.Nutritive value of milk 8
2.4.2.Chemical composition of milk 8
2.4.2.1. Water 9
2.4.2.2.Fat 9
2.4.2.3 Proteins 10
2.4.2.4. Carbohydrates 11
2.4.2.5. Minerals 11
2.4.2.6 Vitamins 11
2.4.2.7. Miscellaneous contents 12
9
2.4.3. Factors affecting composition of milk 12
2.4.3.1. Genetics and environment 12
2.4.3.2. Level of production 13
2.4.2.3. Stage of lactation 13
2.4.3.4. Disease 13
2.4.3.5. Season 13
2.4.3.6.Age (Parity) 13
2.5. Livestock production systems in sudan 14
2.5.1. Nomadic system 14
2.5.2. An Agro- pastoral or Trans humance system 15
2.5.3. Sedentary and semi- sedentary 15
2.5.4. Sedentary system in irrigated areas 15
2.5.5. Commercial production system 16
2.5.6.Other system 16
2.6. Grazing systems 17
2.6.1. Pasture 17
2.6.2. Zero- grazing system 17
CHAPTER THREE 19
MATERIALS and METHODS 19
3.1 Experimental Site 19
3.2. Animals and management 19
3.3. Experimental samples 19
3.4. Chemical composition 20
3.4.1.Fat content 20
3.4.2.Total solid contents 20
3.4.3.Protein content 20
3.4.4. Lactose content 21
3.5 Statistical analysis 22
CHAPTER FOUR
RESULTS 23
11
4.1 The Effect of parity number on chemical composition of cow milk 23
4.2 Effect of production system on chemical composition of cow milk 25
4.3 Effect of interaction between parity number and production system on
chemical composition of cow milk
28
CHAPTER FIVE
DISCUSSION 35
5.1 The Effect of parity number on chemical composition of cow milk 35
5.2 Effect of production system on chemical composition of cow milk 37
5.3 Effect of interaction between parity number and production system on
chemical composition of cow milk
39
Conclusions 40
Suggestions for future work 40
References 41
11
LIST OF TABLES
Page Tables 24 4. 1.The effect of parity number on chemical composition of cow milk 26 Table.4 2. The effect of production system on chemical composition of cow milk
28 Table.4.3 The effect of interaction between production system and parity number
on fat content of cow milk
29 Table.4.4 The effect of interaction between production system and parity number
on total solid content of cow milk
31 Table.4.5 The effect of interaction between production system and parity number
on non solid fat content of cow milk
32 Table.4.6 The effect of interaction between production system and parity number
on protein content of cow milk
34 Table.4.7 The effect of interaction between production system and parity number
on lactose content of cow milk
12
LIST OF FIGURES
Page Figure
24 Figure 4.1.The effect of parity number on chemical composition of cow milk
26 Figure 4.2. The effect of production system on chemical composition of cow milk
28 Figure 4.3. The effect of interaction between production system and parity number
on fat content of cow milk
29 Figure 4.4. The effect of interaction between production system and parity number
on total solid content of cow milk
31 Figure 4. 5.The effect of interaction between production system and parity number on non solid fat content of cow milk
32 Figure 4.6. The effect of interaction between production system and parity number on protein content of cow milk
34 Figure 4.7. The effect of interaction between production system and parity number on lactose content of cow milk
13
CHAPTER ONE
INTRODUCTION
Sudan has the second largest livestock inventories in Africa. Good natural pastures cover
almost 24million hectares and the nomadic pastoral sector accounts for more than 90% of
the huge animal population .cattle and sheep and goats provide an important capital asset
and risk management tool for pastoralists and farmers in times of drought , and they are
increasingly important in agricultural irrigated areas as well (FAO2005). About 90% of
livestock are raised in traditional pastoral systems, mainly in the western states of
Kordofan and Darfur, and in the southern states. Rangelands occupy an area of 110
million hectares. Sudan also produces about 18.6 million tonnes of crop residues (AOAD
1994). Green fodder cultivation, however, is less than 126,000 ha. Rangelands provide
about 86% of feed for livestock, crop residues and agricultural byproducts 10%, and
irrigated forage and concentrates 4%. The rangelands suffer from overstocking in some
areas and understocking in others, from bush fires, deforestation, uneven distribution of
water sources, and the encroachment of both traditional and mechanised agriculture.
The pasture zone in the country extends in a wide belt between the northern desert and
the southern forest for a distance of 1 600 kilometres from east to west and 800
kilometres from north to south. Annual rainfall varies from 250 mm in the north to 875
mm before the humid areas in the south are reached. (Yousif & Fadl El- Moula 2006).
In general the systems of production for cattle in Sudan are not well characterized.
The traditional range grazing system is considered to be the most common and is the
system under which more than 80% of livestock is raised. It includes the pastoral and
semi-pastoral types.
Milk is a translucent white liquid produced by the mammary glands of mammals. It
provides the primary source of nutrition for young mammals before they are able to
digest other types of food.
There are over 264 million dairy cows worldwide, producing nearly 600 million tonnes
of milk every year . The global average for milk production is approximately 2,200 litres
per cow (FAOstat 2012).
14
The exact components of raw milk vary by species but it contains significant amounts of
fat, protein and calcium. In addition to cattle, the milk of buffalo, goat, sheep and yak is
used in our country by humans for manufacture of dairy products. (Gupta 2013).
The variation in milks and milk yield within a species depends on many factors. Some of
these factors are genetics, stage of lactation, daily variation, parity, type of diet, age,
udder health and season (Kilic and Kilic, 1994; Haenlein, 2003).
Milk is a fluid secreted by the mammary glands of mammals to feed their young. It is
a good source nutrients and hence important for growth, repairs and provides energy. The
nutritive value varies with its composition. The composition of cows‘ milk is also of the
greatest importance for the dairy industry. Since, its process ability is highly influenced
by composition. Knowing the composition of milk also helps to assess of adulteration and
the quality of the milk for consumers and milk processing industries. The price of milk
and consumers interest varies with milk components, which may directly affect the farm
income. Despite small contribution of camel and goats, almost 97 % of milk is coming
from cows. In addition to its nutritional value, it is also a means of generating income
(CSA, 2008). Different factors may influence the composition of milk . Information
about variation of milk composition in relation to parity, lactation stage and production
system in cattle is scant.
Objective of the study
The main objective of this study is to assess and compare the chemical composition of
milk produced from cow under traditional and intensive system as affected by parity
number .
15
CHAPTER TWO
LITERATURE REVIEW
2.1. Sudan Livestock resources
Sudan is the second largest animal population in Africa which estimated to be about (105.2),
of which 30.49, 39.6, 30.84 and 4.6 million head of cattle, sheep, goats and camels, respectively
(MARF, 2011). Livestock is the largest subsector of the Sudanese domestic economy and
is a growing contributor to exports. The great bulk of all livestock production – possibly
90% of the total, though the actual figure is not known – comes from small holders and
migratory producers. And have a large number of animal species, breeds, strains and
varieties of indigenous livestock. The origin of these breeds is not very clear despite a
rich history of archeological findings (Epstein, 1971and Payne, 1964). The main
problem is that the breeds are not characterized, especially in areas of tribal contacts. A
part from the animals inhabiting the Nile valley and riverbanks in the country, migratory
tribes own most of the animals (Payne and Elamin, 1978). This has created some
difficulties in defining and characterizing our breeds. The large number of tribal breeds or
strains in the Sudan are mainly designated by external traits, specifically conformation
and sometimes size and branding. The country is so large that obviously some of these
groups of animals are separated geographically for a long time, justifying the assumption
of lack of contact. Thus, each breed must supposedly have a unique set of genes. It will
be very useful if we can identify the relative amount of variation between and within
these populations and species (Nei and Takezaki, 1996). The majorities of breeds is
raised within tribal groups and often carry the name of the tribe. They are well adapted to
the harsh environment and often trek long distances in search of feed and water.
Productivity is low but can be improved with good management in more favourable
conditions. Sudan cattle are mainly descended from Bos taurus, or zebu. In central Sudan
they are generally kept for milk, and in western Sudan for meat production. Sheep are of
the Sudan Desert type, with live weights up to 70 kg and excellent meat and carcass
characteristics. Goats, mostly of the large, black Nubian type, are found in central Sudan
and are kept for milk. There are two types of the single-humped camel, one kept for
16
riding and the other as a pack or baggage animal. Camels are exported mainly for meat
(Fadlalla1 and Ahmed,1999) .
2.2. Cattles domestication
Domestication of cattle has been particularly well documented, with clear evidence of
three distinct initial domestication events for three distinct aurochs (Bos primigenius)
subspecies. B. primigenius primigenius, domesticated in the Fertile Crescent around 8
000 years ago, and B. p. opisthonomous ,possibly domesticated as early as 9 000 years
ago in the northeastern part of the African continent (Wendorf and Schild, 1994), are the
ancestors of the humpless B. taurus cattle of the Near East and Africa respectively.
Humped Zebu cattle (Bos indicus), are now believed to have been domesticated at a later
date, around 7 000 to 8 000 years ago, in the Indus Valley region of modern-day Pakistan
(Loftus et al.,1994; Bradley et al., 1996; Bradley and Magee, 2006). Recently, a
fourth domestication centre has been suggested in East Asia (Mannen et al., 2004), but it
is unclear whether it occurred independently or represents local aurochs introgression in
cattle of Near Eastern origin.
( Epstein 1971) suggested that cattle were introduced to the Sudan from Asia through
the Nile Valley or via the horn of Africa at about 5000 BC for the hump-less African
Zebu and about 2500 BC for humped shorthorns. Thereafter, large introductions
continued until about 670 A.D.
2.3. Cattle breeds in the Sudan
Cattle population in Sudan was estimated to be 29,840.000 million head (MARF,
2012). Among the Sudan cattle population Kenana and Butana are the most promising
indigenous milk breeds, which under improved feeding and management in research
stations yield more than 1500 kg milk per lactation (Saeed et al., 1987; El-Habeeb, 1991
and Musa et al., 2005).
Cattle breeds in the Sudan belong to species Boss indicus. Which include humped
cattle (zebu) of Asia and Africa .Sudanese cattle are broadly classified into breeds:
Nilotic cattle, and North Sudan zebu cattle. (Saeed et al 1987;ElHabeeb 1991 and Musa
et al ,2005).The local breeds in Sudan belong to the group of north Sudan zebu
(McDowell 1972 and Sudanimals 2006).Examples are Butana, Kenana, and Baggara,
17
multipurpose breeds that are used for milk and meat production as well as draught power
(payne and Hodges 1997).
Bennett et al. (1954) classified the Sudanese local cattle into three main groups
Northern or Arab and Southern or NiloLic and the relatively small cattle of the Nuba
mountain, which together constitute the great bulk of Sudanese cattle.( Makkawi et al.
2007) mentioned that Baggara, Butana, Kenana and Nilotiuc are the main four breeds of
cattle in the Sudan.
2.3.1.Kenana breed
The Kenana breed has originated from the humped Bos indicus or Zebu. The light
blue-gray coat is the characteristic color of Kenana cattle . (Yousif & Fadl El- Moula
2006). It has been suggested by Payne (1964) that Zebu cattle were historically imported
into Africa following the movement of migratory people into the continent, and represent
the ancestry of the vast majority of cattle breeds found there today. Other sources
consider that Kenana cattle are the result of inter-breeding the Nilotic Sanga cattle with
the short-horn Zebu during tribal migration before recovered history (Rouse, 1970). The
name Kenana came from the owners also called the Kenana, who are mainly nomadic
and semi-nomadic tribes. Mason and Maule (1960) described Kenana as a sub-type of
the Northern Sudan Shorthorn Zebu. The characteristic colour of the Kenana is light blue-
gray, with gradation from nearly white to steel gray. Shading to nearly black is common
on the head, neck, hump, hind quarters and legs. Black points are also seen on the
muzzle, horns, tail tip and eyes. Calves are frequently born with a brown-red coat that
tends to change to the permanent gray at three to six months of age. The head is long and
coffin-shaped with a thin face. The horns are short and seldom exceed 30-35 cm, and
they are relatively shorter in males than in females. Even though a total lack of horns is
exceptional, animals with loose horns are very common. The hump is cervico-thoracic in
position, it is large in males and tends to hang over at the rear, but is less developed in
females. The dewlap is large and prominent in males. At maturity (about five years) the
average body weights of males and females ranges from 300 kg to 500 kg and 250 kg to
350 kg respectively depending on the managerial conditions (Saeed et al., 1987). Kenana
is the delta between the White Nile and the Blue Nile. It has also spread along the
western and eastern banks of the White Nile and the Blue Nile respectively in a triangular
18
area bounded by the cities of Sinnar, Singeh, Rosiris and Kusti . (Yousif & Fadl El-
Moula 2006).The breed is also found in northern Kordofan state and as far as the area of
the Abbassiya in the eastern part of the Nuba Mountains. The Kenana breed has been
classified as among the highest milk producing northern Sudan Zebu. According to
several reports (Alim, 1960; El Amin and Osman, 1971; Saeed et al., 1987; and
Abdalla et al., 1990) the average milk production per lactation (198-257 days) varies
between 1 400 kg and 2 100 kg. The average birth and weaning (120 days) weights of
Kenana at Umbanein Research Station was found to be 23.0 kg and 52.0 kg respectively
(Saeed et al., 1987; El-Habeeb, 1991)
2.3.2. Butana breed
Butana cattle are found in the Butana plain of central Sudan (between the River Nile,
Atbara River and Blue Nile), a typical semiarid ecological zone (300 mm rainfall, 8
months dry period). This breed is also found in the Gezira between the Blue Nile and the
White Nile and along the River Nile in the northern region. The population size as
reported by Rege (1999) was one million heads and thus, the breed is not at risk
However, the population shows a decreasing trend due to extensive crossbreeding with
European cattle (since 1956) and due to effects of recurrent droughts in 1972/73, 1983/84
and 1989/90 (Mohammed et al 2014).
Butana in Sudan are characterized to have the best milk potential among local breeds
in the country. Under improved feeding and management, Butana yield on average 1500
kg milk and up to 4500 kg per lactation. Unfortunately, their numbers are very small
compared to other less productive types of cattle Musa et al ,2006.
2.3.3. Baggara breed
The name of the breed 'Baggara' means cattle herders in Arabic. This breed was found
in western Sudan and was raised by nomadic tribes in Darfur and Kordofan provinces. Its
homeland is the savannah belt of Central Sudan lying about latitudes 10◦-16◦ N (Osman
and Rizgalla, 1968). Baggara cattle are characterized by a relatively large hump and
short horns. Colours vary enormously though, in this respect the herds of some tribes
show a considerable uniformity. In Southern Darfur, some tribes show a preference for
light-coloured cattle so that it was common to find herds in which the majority of the
cattle are white body colour. The hide is pigmented. In Kordofan region, western Sudan
19
there exist herds which the general body colour was dark-red or brown-red. Musculature
is only moderate and tends to deteriorate from west to east. Baggara cattle in Kordofan
are generally smaller than those in Darfur (Osman and Rizgalla, 1968).
2.3.4. Cross breed in Sudan
The first attempt of cross breeding in Sudan was performed in Belgravia Dairy
Farm(Khartoum North ) in 1925 by using short horn bulls imported from England mated
with native cattle (Butana).Frisian cross breeds were found to perform better ,capacity .
Most crossing operation in Sudan used Kenana and /or Butana as an indigenous breed
with exotic ones. Many herdsmen understand that the best results are obtained by
crossing the best local cattle (usually Butana and Kenana) with exotic breeds (usually
Friesian) (Musa et al 2005). This process of fast upgrading aimed at increasing local
milk production in response to the rising demand in urban areas.
Milk yield from cross breed ,Frisian/Kenana and/or Frisian/Butana,(with 75/ of Frisian
blood) give agood milk yield .Yosif et .al .(1998) attribute the high yield of cross-breed
was significantly influenced by presence of the for the foreign blood. Crossbreeding
Kenana and Butana with B. taurus is probably a useful strategy in riverain areas and
around major towns where sufficient feed and reasonable levels of management can be
provided. However, in nomadic areas probably the best strategy is to use improved
Butana and Kenana bulls for crossbreeding with breeds of poor productivity in harsh
conditions were B. taurus crossbreds cannot survive. This will be a useful contribution to
the improvement of nutrition for people living in harsh environments ( Musa et al 2005).
In Sudan, an economic evaluation of crossbreeding strategy using appropriate economic
evaluation criteria such as used by Kahi et al. (1998) for Kenya is needed to determine
whether the genetic differences between native breeds and European cattle breeds will
yield greater economic benefits.
2.4. Cattle milk
Is a pale liquid produced by the mammary glands of mammals. It is the primary
source of nutrition for infant mammals before they are able to digest other types of food.
Early-lactation milk contains colostrum, which carries the mother's antibodies to its
young and can reduce the risk of many diseases. It contains many other nutrients
including protein and lactose( Pehrsson et al, 2000). Cow have contributed greatly to
21
human welfare supplying draft power, milk, meat, hides, fuel and variety of other
products (Hodgson, 1979). Cow‗s milk has long been considered a highly nutritious and
valuable human food and is consumed by millions daily in variety of products
(Heeschen, 1994).
Throughout the world, there are more than six billion consumers of milk and milk
products. Over 750 million people live within dairy farming households (Hemme. and
Otte2010).
The females of all mammal species can by definition produce milk, but cow's milk
dominates commercial production. In 2011, FAO estimates 85% of all milk worldwide
was produced from cows. (Gerosa and Skoet 2012)
2.4.1. Nutritive value of milk
Milk is an emulsion or colloid of butterfat globules within a water-based fluid that
contains dissolved carbohydrates and protein aggregates with minerals.( Rolf 2002)
Because it is produced as a food source for the young, all of its contents provide benefits
for growth. The principal requirements are energy (lipids, lactose, and protein),
biosynthesis of non-essential amino acids supplied by proteins (essential amino acids and
amino groups), essential fatty acids, vitamins and inorganic elements, and water. (Fox
1995)
Milk has been part of the human diet for millennia and is valued as a natural and
traditional food. As milk provides a substantial amount of vitamins and minerals in
relation to its energy content, it is considered a nutrient dense food( Drewnowski A et
al. 2010)
Cows‟ milk provides a wide range of essential nutrients to the diet. Whilst milk as a
source of calcium is often recognized, it is perhaps less commonly known that milk and
milk products are also an important source of good quality protein, the B vitamins, B2
(riboflavin) and B12, and the minerals iodine, potassium and phosphorus ( Foods
Standards Agency 2002)
2.4.2. Chemical Composition of milk
Milk contains several groups of nutrients. Organic substances are present in about
equal quantity and are divided into elements builders, proteins, and energy components,
carbohydrates and lipids. It also comprises functional elements, such as traces of
21
vitamins, enzymes and dissolved gases, and contains dissolved salts, especially in the
form of phosphates, nitrates and chlorides of calcium, magnesium, potassium and
sodium. It also contains dissolved gases (5% by volume), mainly carbondioxide (CO2),
nitrogen (N) and oxygen (O2) (Gautheron and Lepouze, 2012).
2.4.2.1. Water
For all animals, water is the nutrient required in the highest quantity, and milk
contains a lot of water (88.6%). This amount of water is controlled by the amount of
lactose synthesized by the secretory cells of the mammary gland (Gautheron and
Lepouze, 2012).
2.4.2.2. Fat
The fat content of milk varies depending on whether milk is whole, semi-skimmed or
skimmed. Despite a misconception that milk is „fattening‟, even whole milk contains
only around 3.5% fat (3.5g/100g). Semi-skimmed milk contains 1.7% fat (1.6g/100g or
1.7g/100ml). Skimmed milk contains only 0.1% fat (0.1g/100g or 0.1g/100ml).
(European Parliament and Council 2007).
Unlike protein and carbohydrates, fat composition in milk varies widely in the
composition due to genetic, lactational, and nutritional factor difference between different
species( Fox 1995)
Milk fat contributes unique characteristics to the appearance, texture, flavour and
satiability of dairy foods. Dairy fat is a source of energy, essential fatty acids, fat-soluble
vitamins, and several other components, such as conjugated linoleic acid (CLA) and
sphingolipids (Miller et al 2007). About a quarter of the fat in milk is monounsaturated
(Lock AL et al. 2008). The remainder is mostly saturated fat, although some
polyunsaturated fats and other minor fatty acids are also present.
Palmitic, stearic and myristic acids are the major saturated fats found in milk (Miller et
al 2007). Dairy fat is also comparatively rich in the short and medium chain saturated
fats. Research continues to unravel the complexities associated with individual fatty acids
and fats from different sources and it is becoming increasingly apparent that not all fatty
acids, or saturated fatty acids, have the same biological effects. There are a variety of
saturated fatty acids in milk and many of these have no effect on plasma cholesterol(
Lock AL et al. 2008)
22
Eckles et al ( 2004) reported that the milk fat is the most valuable constituent of milk, it
is the food value of the milk .It was found that the fat content as the average percentage
to give 3.8%. Fat gives milk its characteristics of smoothness, flavor and color and it
contains around sixty six different fatty acids emulsified and dispersed in water in small
globules ,each globule being surrounded by a membrane to prevent fusion
(Chamberlain ,1990). Kordylas (1991) reported that the milk fats contain high
proportion of short –chain fatty acids especially butyric acid , and enzymes such as
phosphatase and lipases that affect the flavor of milk .The fat content of milk is often
used as aguide to the quality of the milk , and may affect its price (Tull,1996). The fat-
soluble vitamins A, D, E, and K along with essential fatty acids such as linoleic and
linolenic acid are found within the milk fat portion of the milk (McGee 2004)
2.4.2.3. Proteins
Milk is a good source of high quality protein (Miller et al, 2007). Cows‟ milk
contains about 3.5% protein by weight, and of this total protein, 80% is casein and 20%
whey. Casein is the dominant protein in milk and can be fractionated into four major
components: alpha, beta, gamma and kappa-casein. Whey protein is composed
predominantly of beta-lactoglobulin and alpha-lactalbumin, but other whey proteins
include serum albumin, immunoglobulins (IgA, IgG, IgM), protease peptones, lactoferrin
and transferrin(Miller et al, 2007).
Normal bovine milk contains 30–35 grams of protein per liter of which about 80% is
arranged in casein micelles. Total proteins in milk represent 3.2% of its composition
The largest structures in the fluid portion of the milk are "casein micelles":
aggregates of several thousand protein molecules with superficial resemblance to a
surfactant micelle, bonded with the help of nanometer-scale particles of calcium
phosphate. Each casein micelle is roughly spherical and about a tenth of a micrometer
across. There are four different types of casein proteins: αs1-, αs2-, β-, and κ-caseins.
Collectively, they make up around 76–86%Fox (1995). of the protein in milk, by weight.
Most of the casein proteins are bound into the micelles( McGee, 2004).
Milk contains dozens of other types of proteins beside the caseins including
enzymes. These other proteins are more water-soluble than the caseins and do not form
larger structures. Because the proteins remain suspended in the whey left behind when
23
the caseins coagulate into curds, they are collectively known as whey proteins. Whey
proteins make up approximately 20% of the protein in milk, by weight. Lactoglobulin is
the most common whey protein by a large margin( McGee 2004)
2.4.2.4. Carbohydrates
The principal carbohydrate found in milk is lactose. Cow‟s milk contains about
4.5g lactose per 100g milk and there is some evidence that lactose is the least cariogenic
of the common dietary sugars. In addition, various other components of milk have been
considered to be protective against dental caries( Bánóczy J et al, 2009).
A simplified representation of a lactose molecule being broken down into glucose
and galactose. Milk contains several different carbohydrate including lactose, glucose,
galactose, and other oligosaccharides. The lactose gives milk its sweet taste and
contributes approximately 40% of whole cow's milk's calories. Lactose is a disaccharide
composite of two simple sugars, glucose and galactose. Bovine milk averages 4.8%
anhydrous lactose, which amounts to about 50% of the total solids of skimmed milk.
Levels of lactose are dependent upon the type of milk as other carbohydrates can be
present at higher concentrations that lactose in milks( Fox, 1995)..
2.4.2.5. Minerals
Minerals are traditional names for a variety of cations and anions within bovine
milk. Calcium, phosphate, magnesium, sodium, potassium, citrate, and chlorine are all
included as minerals and they typically occur at concentration of 5–40 mM. The milk
salts strongly interact with casein, most notably calcium phosphate. It is present in excess
and often, much greater excess of solubility of solid calcium phosphate( Fox 1995).
2.4.2.6. Vitamins
Milk is a good source of many other vitamins. Vitamins A, B6, B12, C, D, K, E,
thiamine, niacin, biotin, riboflavin, folates, and pantothenic acid are all present in milk
(Fox 1995).
Milk is a good source of the B vitamins, riboflavin or B2 and B12. Significant
amounts of riboflavin are present in milk( Foods Standards Agency 2002). Riboflavin is
necessary for the release of energy from foods and the health of the body‟s membranes
including the skin. It is also crucial for the maintenance of normal vision, normal red
24
blood cells and functioning of the immune system. Riboflavin further contributes to the
protection of DNA, proteins and lipids from oxidative damage( EFSA, 2010).
Vitamin B12 is required for the maintenance of healthy nerves and red blood cells, as
well as normal energy production and cell division. It is also needed for normal function
of the immune system, neurological and psychological function, and reduction of
tiredness and fatigue( EFSA, 2010).
Miscellaneous contents 2.4.2.7.
Other components found in raw cow's milk are living white blood cells, mammary
gland cells, various bacteria, and a large number of active enzymes (McGee, 2004).
2.4.3. Factors affecting composition of milk
Many factors influence the composition of milk, the major components of which are
water, fat, protein, lactose and minerals.
Nutrition or dietary influences readily alter fat concentration and milk protein
concentration. Fat concentration is the most sensitive to dietary changes and can vary
over a range of nearly 3.0 percentage units. Dietary manipulation results in milk protein
concentration changing approximately 0.60 percentage units. The concentrations of
lactose and minerals, the other solids constituents of milk, do not respond predictably to
adjustments in diet (Looper,2014)..
Milk composition and component yields also can be affected by genetics and
environment, level of milk production, stage of lactation, disease (mastitis), season and
age of cow.
2.4.3.1. Genetics and Environment
A change in milk composition using traditional breeding techniques occurs slowly,
although new techniques of genetic manipulation may allow faster progress in the future.
Yields of milk, fat, protein and total solids are not easily impacted by genetics;heritability
estimates for yield are relatively low at about 0.25. Meanwhile, heritability estimates for
milk composition are fairly high at 0.50. Conversely, environmental factors such as
nutrition and feeding management will impact yield more than the actual percent
composition of the major milk constituents. The priority placed on each genetic trait
depends upon its economic or profit impact. Milk yield per cow tends to receive the most
attention by producers. However, component yields should not be overlooked. Genetic
25
selection should be directed toward increasing fat, protein and nonfat solids yields. But,
because component percentages tend to have negative genetic associations with yield
traits, a change in these percentages is not likely to be achieved through genetic selection
alone(Looper,2014).
2.4.3.2. Level of Production
(Looper,2014).Yields of fat, protein, nonfat solids and total solids are highly and
positively correlated with milk yield. Under selection programs that emphasize milk
yield, fat and protein yields also increase. However, the percentages of fat and protein in
the total composition decrease.
2.4.3.3. Stage of Lactation
The concentration of milk fat and protein is highest in early and late lactation and lowest
during peak milk production through midlactation. Normally, an increase in milk yield is
followed by a decrease in the percentages of milk fat and protein, while the yields of
these constituents remain unchanged or increase (Looper,2014)..
2.4.3.4. Disease
Although other diseases can affect milk component content and distribution, mastitis has
been the predominant disease studied. Mastitis results in a reduction in fat and casein
content and an increase in whey content of milk. These changes in the milk proteins, in
conjunction with alterations in lactose, mineral content and milk pH, result in lower
cheese yields and altered manufacturing properties. Milk from cows with elevated
somatic cell counts (greater than 500,000 somatic cells/ml) has longer coagulation time
and forms weaker curds than milk from cows with lower somatic cell counts
(Looper,2014)..
2.4.3.5. Season
Milk fat and protein percentages are highest during the fall and winter and lowest during
the spring and summer. This variation is related to changes in both the types of feed
available and climatic conditions. Lush spring pastures low in fiber depress milk fat. Hot
weather and high humidity decrease dry matter intake and increase feed sorting, resulting
in lower forage and fiber intake (Looper,2014).
26
2.4.3.6. Age (Parity)
While milk fat content remains relatively constant, milk protein content gradually
decreases with advancing age. A survey of Holstein Dairy Herd Improvement
Association (DHIA) lactation records indicates that milk protein content typically
decreases 0.10 to 0.15 unit over a period of five or more lactations or approximately 0.02
to 0.05 unit per lactation. In addition to the increase of milk production with age, there is
a slight decrease in the SNF and fat per cent through the fifth lactation, beyond which
there is little change(Looper,2014)..
2.5. Livestock Production systems in Sudan
In general the systems of production for cattle in Sudan are not well characterized.
The traditional range grazing system is considered to be the most common and is the
system under which more than 80% of livestock is raised. It includes the pastoral
and semi-pastoral types. The pasture zone in the country extends in a wide belt between
the northern desert and the southern forest (Yousif & Fadl El- Moula 2006).
About 80% of the livestock is under the traditional production system. There are
about five productions systems in the country, mainly:
2.5.1. A Nomadic System
In the nomadic system, the family depends on livestock production for their livelihood.
Movement is based on regular North- South, tuned to the rhythm of rainfall and the
availability of pasture and water .In some regions especially Dar Fur some tribes cross
the borders to Chad and Central Africa.
Cattle are very popular in nomadic areas. The Baggara cattle are the main source of meat.
Some additional meat is contributed by Kenana cattle, which move from Damazine areas
to the Butana area during the rainfall.
Camels move from North to South near the borders of the Southern regions of the Sudan.
They are occasionally faced with sporadic cases of local consumption (Fadlalla1 and
Ahmed1999).
Small ruminants are there, but they move shorter distances. They are mainly used for
local consumption and export. It is worth mentioning that in this system, animals never
receive any supplementation and are mainly dependent on natural grasses. During the dry
27
season the nutritive value of the grasses is poor and some animals may starve to death.
There are also episodes of drought which cause a lot of losses (Fadlalla1 and
Ahmed1999).
2.5.2. An Agro-Pastoral or Trans humance System
In this system families depend predominantly on livestock production but they grow their
own grains during the rainy season. For instance, in western Sudan the cultivated lands
are in the way of the migrating tribes with their animals. They usually arrive to the
agricultural lands at the beginning of the cultivation season. Some members of the family
may be looking after the animals while others take care of farms. Cattle are the major
animals in this system. Sheep and goats are also found but in less important numbers. All
the animals are of local breeds and are fully dependent on pasture until harvest, when
they graze the after harvest. The herd size varies from some hundreds to thousands. They
are the main suppliers of the local markets with meat and contribute to export animals
(Fadlalla1 and Ahmed1999).
2.5.3. The sedentary and semi-sedentary system
In this system families are fully dependent on agriculture. Farmers stay in their villages
and rear the animals in the vicinity on the natural pasture. Animals may get access to
grasses in the cultivated areas after harvest. During the dry period animals are moved to
various places in search of pasture. Some time and in some localities they return to the
water sources to water their animals. They may take grains and other supplements for
their own consumption .The most important species are sheep, goats, cattle and camels
these are all local breeds, and are highly affected by fluctuations in rainfall, all the
availability of pasture. The number of animals holding per family ranges between10-60
cattle, 30-300 in sheep, 30-150 in goats and 19-100 in camels. There are also many types
of local breeds of poultry, which provide eggs and meat (Fadlalla1 and Ahmed1999).
2.5.4. A Sedentary System in Irrigated Areas
This system is predominantly in the Central and Northern Sudan along the riverside.
There are large and medium sized projects where sorghum; wheat, cotton, groundnut,
sugar, rice and sunflower and fodder crops are grown .In addition to some gardens.
Farmers depend on cultivation and rear some cattle especially dairy cattle, sheep and
goats. The majority of the animals are local breeds with few crossbreeds. The number in
28
the cattle herd ranges from 5 to 60 heads of sheep range from 10-150 and goats 10-200.
In addition to many types of local breeds of poultry and some foreign breeds.
Animals depend on the natural pasture and agricultural by products. In some areas there
are also industrial by products. Unlike the sedentary systems more milk is produced in
the irrigated areas. Also, these animals provide meat to the urban areas. The national
policy is aimed at the integration of livestock in agriculture and some fodder crops are
produced but there is no clear policy on the part of the Government for this
sector(Fadlalla1 and Ahmed1999).
2.5.5. Commercial production system
The system is based on commercial production. Wealthy persons carry out this system
since it needs more input. There is some specialization in the production process. It is
worth mentioning that there is no beef production per se but young calves are collected
from different localities and reared in feedlots and finishing units. This includes: Milk
cooperatives, specialized large dairy enterprises and individuals that own high producing
milking cows. The system is particularly seen around big towns (Fadlalla1 and
Ahmed1999).
Feedlots for fattening cattle and sheep trekked for long distances from the western
regions of the country to urban areas and markets. Fattening is also practiced in big
privately owned rainfed mechanized agricultural schemes on crop residues. There are
three types of commercial farms: Dairy Farming System, Commercial finishing System.
And Poultry farming System.
2.5.6. Other system
Other animal production systems include ranching, feedlot operations and peri-urban
backyard livestock production. Ranching is a recent trend in Sudan. Animals are raised
for meat on natural rangelands in western Sudan in Kordofan and Darfur, and in Butana
in Kassala State. Poor range management within the ranch is, however, a major
constraint. Feedlots have existed for over 30 years. Animals, mainly beef cattle, are
brought on the hoof from western Sudan and fattened in Khartoum State on sorghum
grain, oilseed cakes and roughage, with gains of up to 1 kg/day in cattle and 0.35 kg in
sheep. Near and within urban areas, goats and poultry fed on household waste are kept
for domestic supply (Fadlalla1 and Ahmed1999)
29
2.6. Grazing Systems
. Grazing system is a broad "umbrella" term and is defined as "any integrated
combination of animal plant and other environmental components and the grazing
method by which the system is managed to meet specific results or goals.
Grazing systems provide high-quality forage and reduce feed and veterinary costs
while avoiding manure buildup, they also provide a continuous soil cover, thus protecting
wildlife habitats and important ecosystems. Grazing systems rely on two primary
resources: pasture, the lowest cost source of feed available (Soder and Rotz 2001), and
the dairy farmer‘s management skills.
2.6.1. Pasture
Pastures are sources of forage and nutrients for dairy cattle including heifers, dry
cows and the milking herd. The use of pasture for dairy cows is less expensive feeding
system because grazed forage is the cheapest source of nutrients (Peyraud and Delaby,
2001; Clark and Kanneganti, 1998). Cows kept on natural pastures with different types
of vegetation will vary their feeding behaviour and browse on twigs from deciduous
trees. Cattle are highly motivated to look for food and will forage for 6 to 10 hours a day
(Tucker 2009).
The national Sudanese herd depends mainly on natural range, particularly the traditional
one which is considered the main producer of milk in the Sudan. The traditional sector
possesses 90% of animal population and it produces about 95% of total milk yield and
the remaining 5% is produced in cities (Hassabo, 2009). Full grazing practice also called
free range, is mainly practiced by pastoralists Dairy cattle under this practice graze freely
in the rangeland for 9 to 12 hours (Sarwatt and Njau, 1990) and then they are confined
into night bomas.
2.6.2. Zero –grazing system
Zero grazing practice is also called cut and carry system. It involves total
confinement of animals in the barn or shed and feeds are brought to the animal. The
system is highly practiced in densely populated areas, where there is shortage of grazing
land and relatively sufficient availability of labour (Aminah and Chen, 1989). Under the
zero-grazing system, cattle are confined in one place where feed and water are brought to
31
the animals. Other animal husbandry activities such as animal health, are also carried out
under zero grazing.
Zero-grazing is a good system for keeping dairy cattle in densely populated, high
potential areas, where land per farm family is small
Generally, the main advantages of the zero-grazing system are:
• Cows are confined and therefore use most of the energy from feeds for growth and milk
production.
• Saves land for other enterprises by allowing the use of high yielding fodder crops like
Napier. Enables on farm clean milk production.
•Good calf rearing is possible Manure can be easily collected for the benefit of fodder
crops the animals are better protected against diseases, especially tick-borne diseases.
Close observation of the animals is possible, making heat detection and attendance to
animals easier and faster. The animals are kept inside which is more secure and protect
them from attack by predators. Little or no time is spent on herding the animals.
Therefore labour for other farm tasks are saved.
The disadvantages of this system are: Much labour is required to take feed and water to
the animals.Much capital is required for construction of a ‗zero-grazing unit. The
possibility that animals are stressed because of too much confinement inside the zero
grazing units.( Program coordination Unit 2010)..
31
CHAPTER THREE
MATERIALS AND METHODS
3.1 Experimental Site
This study was conducted in Kenana area at June 2016, which is located in a semi-arid
zone and characterized by three marked seasons, namely winter (November-February),
hot or dry summer (March-June) and wet summer (July-October). The latter is considered
to be the rainy season. According to meteorological data in Kenana region, the average
annual rainfall is 356 mm, while the peak of the rainy season occurs in August (114 mm)
and the least wet time being in October (10.6 mm). There are also some rains in May and
June. Humidity is relatively high in the wet summer (80.0-63.0 %) and low in the dry
summer (60.0-27.0 %). The mean daily temperature is 27.4°C with the highest and lowest
temperatures of 45°C and 10.8°C recorded in May and January respectively. The
dominant vegetations of the natural pasture are Acacia tortilis, Maeura crassifolia,
leptodania pyrotechnica and Acacia seyal.
3.2Animals and management
The study was conducted on 18 lactating cross breed cows (Kenana or Butana with
Frisian). (9 cows from a traditional pastoral herd and 9 cows from a dairy farming system
in Kenana Dairy Farm .during the dry season. The animals in traditional system were
herded to the fields in the morning after milking to graze natural forages and crop
residues. All cows in early lactation stage.
The diet of the farming system composed of concentration in 7Am and 4 pm. In addition
green forage were given in period between 9am-1pm. plus good water supply. Cows
ranging from 1st, 3rd and 5th parity, were selected from each of the two herds for this
study. All measurement were replicated three times to improve the reliability of the
results.
3.3 Experimental samples
Samples of milk (200ml) were collected from each lactating cow early morning at
milking time (7:00) in clean bottles, thoroughly mixed and immediately transferred to the
32
laboratory of kenana Dairy Farm for analysis at room temperature. All samples of the two
groups from herd and same parity.
3.4. Chemical composition
3.4.1. Fat content
The fat content was determined by Gerber method according to AOAC (1990). 10 ml of
sulphuric acid (density 1.815gm /ml at 20 °C ) were poured into clean dry Gerber tubes,
then 10.96 ml milk were added followed by the addition of 1 ml amyl alcohol and
distilled water at 20 °C the content were mixed well and centrifuged at 1100 revolutions
per minute (rpm) for 5 minutes. The tubes were transferred to a water bath at 65 °C for 3
minutes and then the fat content was immediately read.
3.4.2 Total solids content
The total solids content was determined according to the of AOAC (1990). 5 gm of milk
were placed in to a clean dried aluminum dish. The weight of the sample and dish were
recorded.The dishes were transferred to an air oven for 12 hours at 75°C .The dishes were
placed in to desiccators to cool and then weighted. Heating, cooling and weighing were
repeated several times until difference between two successive weighing was less than
0.5mg.The total solid content was calculated as follows:
Total Solid % = W1 ×100
W0
Where:
W1 =weight of sample after drying.
W0 =weight of sample before drying
3.4.3 Solid non Fat content Solid non fat content of the milk was determined by
subtracting the fat percentage from of total solids percentage ( Richardson(1985) .
3.4.4 Protein content
The protein content was determined by Kjeldah method according to AOAC (1990). 10
gm of the sample were transferred to Kjeldahi digestion flask. Catalyst mixture (96%
anhydrous sodium sulphate, 3.5% copper sulphate and 0.5% selenium dioxide) and 3 ml
of concentrated sulphuric acid were added to the digestion flask. It was heated strongly
33
until the liquid had become clear. The digested sample of milk and 15 ml of NaOH (40
%) were added to Kjeldah distillation apparatus. Ten ml of boric acid (2 %) and 3 drops
of indicator (methyl red) were added to a receiving flask. The distillation was continued
until the distillate in the receiving flask was 75ml. The distillate was titrated against HCL
(0.1 N) until a lasting faint pink color was obtained.
Calculation:
Nitrogen % = T×0.1×20×0.014 ×100
Weight of sample
Protein = Nitrogen % × 6.38
Where:
T= titration figure
0.1 = Normality of HCL.
0.014= Atomic weight of nitrogen /1000
20= dilution factor.
6.38= Conversionfactor.
3.4.5 Lactose content
Lactose was determined by anthrone method (Richard, 1959).
Preparation of solution
The standard solution was prepared by dissolving five mg lactose
into 95 ml of distilled water to give 5% (w/v) solution of monohydrate. One ml of this
solution was diluted with 500 ml distilled water in 500 ml volumetric flask to give 95 mg
lactose/ml standard solution. The Anthrone reagent was prepared by dissolving 150 mg
of Anthrone into 100 ml of 70% (w/v) sulfuric acid. The solution was then cooled and
stored over night.
Procedure
One ml of sample was pipetted into a 500 ml flask with distilled water. The
solution was then mixed thoroughly and 0.5 ml was transferred to boiling tube (sample)
standard stock solution (0.5ml) was transferred to a second boiling tube (standard) and
(0.5 ml) distilled water transferred to third boiling tube (blank). To each tube, ten ml ice
cooled Anthrone reagent was added. The tubes were held in the boiling water bath for six
34
minutes. The tubes were then transferred to an ice bath and held for 30 minutes. The
optical density (OD) was read at 625 nm.
Lactose content (in mg/100ml) was calculated as follows:
Lactose= O.D (S) - O.D (B) ×4.75
O.D(SD) – O.D(B)
Where: O.D(S) = Optical Density of Sample.
O.D (SD) =Optical Density of Standard.
O.D (B) = Optical Density of Blank
3.5 Statistical analysis
Data obtained were summarized, coded and subjected to various statistical analusis
tools in General Linear Model (GLM) procedure. Multivariate analysis of variance were
performed using Statistical packages for social science (SPSS) release 15.00 (2006)
software to compare the relationship among parameters studied.
35
CHAPTER FOUR
RESULTS
4.1. The Effect of parity number on chemical composition of cow milk
Table.4.1. Showed the mean values of chemical composition of cow milk from different
parity number. Parity effect was not significant (p < 0.05) difference on chemical
composition of cow milk except for fat and total solid
Parity effect was significantly (p < 0.05) difference on fat. Highest values (4.15) of fat
were recorded for cow in first parity followed by cow in third parity (3.24) and cow in
fifth parity (1.95) in descending order. First parity milk contained more fat than the
subsequent parities
There was significant (p < 0.05) difference among parity for total solid. The total solid
content showed a decreasing pattern with advancing parities. The least total solid content
was obtained in cow with fifth parity, while the highest total solid was recorded for cows
in their first parity
The result indicated that parity number had no significant (p < 0.05) effect on solid non
fat, protein and lactose. The highest solid non fat was observed for cow in their third
parity, while lowest was evident in cow at fifth parity
The highest protein content was recorded for milk from cow in third parity which was
significantly (p < 0.05) higher than the other parities
The result indicated that parity number had no significant (p < 0.05) effect on Lactose.
Cow in third parity had the highest values 4.72 for the lactose, while the lowest values
showed in cow at fifth parity.
Figure 4.1. Showed the effect of parity on chemical composition of cow milk, best values
of most parameters recorded in cow at third parity, while the lowest values showed in
cow at fifth parity.
36
Table .4. 1.The effect of parity number on chemical composition of cow milk
Items Parities Sig. level
1 3 5
Fat 4.15a ± 0.39 3.24b ±0.21 1.95c±0.08 *
Total solid 12.75a ±0 .43 12.02a ±0.40 10.24b ± 0.27 *
Solid Non Fat 8.61 a ± 0.26 8.74 a ±0.26 8.29 a ± 0.24 NS
Protein 3.10 a ± 0.11 3.16 a ±0.09 2.99 a ±0.10 NS
Lactose 4.58 a ±0.16 4.72 a ±0.14 4.40 a ± 0.15 NS
Raws with the same superscript in this and the subsequent tables are not significantly
different (P >0.05)
1= mean first parity * = mean significant different
3= mean third parity Ns = mean not significant
5= mean fifth parity
Figure 4.1.The effect of parity number on chemical composition of cow milk
0
2
4
6
8
10
12
14
fat TS SNF protein lactose
first parity
third parity
fifth parity
37
4.2. Effect of production system on chemical composition of cow milk
Table.4. 2 showed the mean values of chemical composition of cow milk from different
production system (traditional and intensive).The result indicated that production system
had affected significantly all parameter except fat. The fat content was not significantly
difference among production system, highest value (3.26) of fat observed in intensive
system, while least fat recorded by traditional system.
The total solid obtained from cow milk in traditional system was significantly difference
from cow in intensive system.cow in traditional system recorded highest values (12.19)
solid non fat content of cow milk samples collected from traditional system revealed
significantly (p<0.01) higher values than those obtained from the intensive system
Chemical analysis of cow milk in Table 4.2 revealed significantly (p<0.05) higher protein
content in milk samples obtained from the traditional system,
Lactose content were significantly (p<0.05) lower in milk samples collected from
intensive system
Figure 4.2. Showed the effect of production system on chemical composition of cow
milk. The result indicated that best value of all parameters observed in traditional system
38
Table.4 2. The effect of production system on chemical composition of cow milk
Figure 4.2. The effect of production system on chemical composition of cow milk
0
2
4
6
8
10
12
14
Fat TotalSolid
SolidNon Fat
Protein Lactose
Traditional system
Intensive system
Items Production System Sig. level
Traditional Intensive
Fat 2.97 ±0.92 3.26 ±1.78 NS
Total Solid 12.19a ± 1.69 11.15b ± 1.96 *
Solid Non Fat 9.21a ±0.94 7.89b ±0.74 *
Protein 3.34a ±0.36 2.82b ± 0.29 *
Lactose 4.96a ± 0.56 4.17b ± 0.42 *
39
4.3. Effect of interaction between parity number and production system
on chemical composition of cow milk
Table.4. 3 Showed the effect of production system and parity number on cow milk fat.
The interaction was significantly (p < 0.05) difference for fat of cow milk. Best values of
fat were showed by traditional system for cow in third parity (3.89) followed by cow in
first parity (2.81), while highest value in intensive system recorded by cow in first parity
(5.48) followed by cow in third parity (2.60).
Figure 4.3. Showed the effect of production system and parity number on cow milk fat.
The result shows that the cow in fifth parity reported lowest value in both production
systems.
Table 4.4. Showed the effect of production system and parity number on total solid of
cow milk. The interaction was significantly (p < 0.05) difference for total solid of cow
milk. Highest value of total solid recorded by cow in first parity for intensive system.
While highest values of total solid were showed by traditional system for cow in third
parity.
Figure 4.4. Showed the effect of production system and parity number on cow milk total
solid. The result showed that the cow in fifth parity reported lowest value in both
production systems.
41
Table.4.3 The effect of interaction between production system and parity number on fat
content of cow milk
Parity Traditional system Intensive system Sig. level
First parity 2.81b±0.99 5.48a±0.90 *
Third parity 3.89a ±0.40 2.60b±0.80 *
Fifth parity 2.21a ±0.07 1.69b±0.26 *
Figure 4.3. The effect of interaction between production system and parity number on fat
content of cow milk
0
1
2
3
4
5
6
First parity Third parity Fifth parity
Traditional system
Intensive system
41
Table.4.4 The effect of interaction between production system and parity number on total
solid content of cow milk
Parities Traditional system Intensive system Sig. level
First parity 12.04b ± 2.28 13.47a ± 0.95 *
Third parity 13.37a ± 0.90 10.66b ± 1.07 *
Fifth parity 11.17a± 0.72 9.31b± 0.51 *
Figure 4.4. The effect of interaction between production system and parity number on
total solid content of cow milk
0
2
4
6
8
10
12
14
First parity Third parity Fifth parity
Traditional system
Intensive system
42
Table 4.5. The interactions were not significant (p<0.05) for solid non fat. The results
indicated that cow in third parity showed the highest value of solid non fat (9.42, 8.06),
followed by cow in first parity (9.22,7.99), and cow in fifth parity (8.97, 7.61) in
descending order for traditional and intensive system respectively.
Figure 4.5. Showed the effect of production system and parity on solid non fat cow milk.
The result showed that the cow in fifth parity ranked third in traditional and intensive
system
Table .4.6 showed the effect of interaction between production system and parity number
on protein of cow milk. The interaction was not significantly (p < 0.05) difference for
protein of cow milk. Best value of protein for traditional system noticed in cow from
third parity (3.38) followed by cow from first parity (3.37) and cow in fifth parity (3.27)
in descending order. Intensive system followed the same sequence of traditional system.
Figure 4.6. Showed the effect of production system and parity number on cow milk
protein. The result showed that the cow in fifth parity reported lowest value in both
production systems.
43
Table.4.5 The effect of interaction between production system and parity number on solid
non fat content of cow milk
Parities Traditional system Intensive system Sig. level
First parity 9.22±1.30 7.99±0.30 NS
Third parity 9.42±0.72 8.06±0.99 NS
Fifth parity 8.97±073 7.61±075 NS
Figure 4. 5.The effect of interaction between production system and parity number on
non solid fat content of cow milk
0
1
2
3
4
5
6
7
8
9
10
First parity Third parity Fifth parity
Traditional system
Intensive system
44
Table.4.6 The effect of interaction between production system and parity number on
protein content of cow milk
Parity Traditional system Intensive system Sig. level
First parity 3.37±0.51 2.83±0.12 NS
Third parity 3.38±0.28 2.94±0.35 NS
Fifth parity 3.27±0.30 2.70±0.33 NS
Figure 4.6. The effect of interaction between production system and parity number on
protein content of cow milk
0
0.5
1
1.5
2
2.5
3
3.5
First parity Third parity Fifth parity
Traditional system
Intensive system
45
Table 4.7 showed the effect of interaction between production system and parity number
on lactose of cow milk. The interaction was not significantly (p < 0.05) difference for
lactose of cow milk. The cow in fifth parity revealed the lowest value of lactose in both
production system compared with cow in first and fifth parity. Cow in third parity had the
highest value for lactose, while the cow in first parity ranked second for traditional and
intensive system.
Figure 4.7. Showed the effect of production system and parity number on cow milk fat.
The result shows that the cow in fifth parity reported lowest value in both production
systems.
46
Table.4.7 The effect of interaction between production system and parity number on
lactose content of cow milk
Parity Traditional system Intensive system Sig. level
First parity 4.97±0.76 4.19±0.17 NS
Third parity 5.09±0.44 4.35±0.50 NS
Fifth parity 4.82±0.45 3.98±0.48 NS
Figure 4.7. The effect of interaction between production system and parity number on
lactose content of cow milk
0
1
2
3
4
5
6
First parity Third parity Fifth parity
Traditional system
Intensive system
47
CHAPTER FIVE
DISCUSSION
A study on milk composition is of most important to evaluate the milk production ability
of milking animals. The present study described the effect of parity order and production
system on milk composition in dairy cow in Kenana area.
5.2. Effect of parity order on chemical composition of cow milk
The results obtained in the present study can only partly be confirmed by other
authors. According to Lacy-Hulbert et al. (1999) and Felenczak et al. (2001), yield,
composition and quality of milk are varying due to numerous factors from which many
are correlated. They include genotype, cow‘s age, stage of lactation, milking frequency,
hygiene of milk collection, season of the year, feeding system and feeding ration
composition.
In the present study the chemical composition of milk collected from experimental
animals showed wide variability with inconsistent pattern for almost all the studied
components. This great disparity in composition had exerted their effect on the mean
composition of milk for each group of experimental animals in different parities. The
present result agreement with result obtained by (ELkhider 2011)
In the current study, the hypothesis that animals in later parities have better milk
quality than animals in early parities did not prove to be true for cows in this study.
Studies have shown that, increase in body weight of animals with high number of
lactations leads to a greater availability of body reserves for the synthesis of milk
components and also result in an increased synthesis of milk constituents (Sevi et al.,
2000).
The differences in milk composition observed between the parity orders in the present
study are contradictory with the results obtained by other authors.( Czaplicka et al.
(2001) reported the increase of fat, protein, lactose and total solids yields along with the
increase of cows‘ age. In the present investigation the values of chemical composition of
cow milk lower than the result reported by (Węglarz et al, 2008)
Parity effect was significantly (p < 0.05) difference on fat content. The finding in this
study was in line with Yadav et al (2013) and Konečna et al. (2011). However, the
48
finding disagrees with the finding reported by Pratap et al.,(2014), Gurmessa and
Melaku (2012) , and Rani et al 2011 .
Fat content (Table 4.1) was lower in cow in third (3.24) and fifth parity (1.95) and
significantly increased in first parity (4.15), i.e. fat percent decrease with advanced
parities. The present study agreement with result reported by Dubey et al. (1998)
reported highest milk fat content during first parity in buffaloes and Ludwiczuk et al.
(2001) found a lower milk yield and a noticeable lower content of fat in older cows .
Similarly the fat percentage varied significantly among the parities with no consistent
increase over the advancement of the parities (Anderson 1985).
The parity had significant effect on contents of total solids, which correspond to the
results published by Konečna et al. (2011) reported a significant effect of the parity on
contents of total solids. On the contrary, Pokorna et al. (2010) found no significant
effect of parity on total solid. Total Solid in the present study decrease with advanced
parities. The present study agreement with result reported by Ludwiczuk et al. (2001)
found a lower content of total solids in older cows. With regard to the average contents of
total solid and fat, these were higher on the first parity, which is in agreement with the
results of study carried out by Konečna et al. (2011). On the other hand, Sevi et al.
(2000) reported the opposite trend.
Solid Non Fat content of milk in the current study was not significant difference
among different parities. The finding agrees with the finding reported by Pratap et al.,
(2014)
Protein content in this study were not significantly affected by parities order, these
results were supported by Pratap et al.,(2014), Pokorna et al. (2010) and Yadav et al
(2013) found milk protein level did not vary significantly over the parities. On the other
hand, Sevi et al. (2000) found a significant effect of the parity on protein contents, also
Konečna et al. (2011) reported a significant effect of the parity on contents of protein.
The average value of protein content was slightly higher in cows at third parity in the
present study which is in agreement with the results of study carried out by Sevi et al.
(2000) and Oravcova et al. (2007) reported higher average protein content on the third
parity.
49
The parity had no significant effect on contents of lactose, which confirmed to the results
obtained by Pokorna et al. (2010), Yadav et al (2013) and Pratap et al.,(2014).. On the
contrary, Sevi et al. (2000) found a significant effect of the parity on lactose content; also
Konečna et al. (2011) reported a significant effect of the parity on contents of lactose.
The average of lactose content were slightly higher for the third parity(4.72) when
compared with the fifth parity (4.40) which is contrast with the results reported by
Novotna et al. (2009) and Pokorna et al. (2010). Increase in the lactose content in third
parity is a reflection of more water content available for lactose synthesis due to higher
milk yield. Available water content for lactose synthesis reduces in later stage of lactation
due to less milk production. A close relationship between lactose synthesis and the
amount of water drawn into milk makes lactose a stable milk component by Pollott
(2004).
5.2. Effect of production system on chemical composition of cow milk
Milk yield and composition are considerably influenced by the season of the year and
consequently by the differences in cows‘ feeding. milk fat composition is also influenced
by feed types making different types of substrates available for synthesis of milk. It
suggested that desirable composition of milk may be obtained from animals of
appropriate physiological/lactation stage and parity fed with special feed ingredients, in
the dairy production system.
Results revealed that cow milk composition was significantly affected by production
system (p < 0.05). The highest percentage of total solid Table (4.2), (12.19), solid non fat
(9.21), protein (3.34) and lactose (4.96) were recorded for traditional system. In contrast,
these components were the lowest under intensive system.
Production system effect was not significantly (p < 0.05) difference on fat content. Fat
content was higher in the intensive system than traditional system (3.26 vs 2.97). These
decreases in values of cow fat components of traditional system might be due to
insufficient nutrient supplements and limitation of animal health care in comparison with
those of intensive system. The fat content obtained was slightly lower when compared to
4.6 to 4.7 % obtained in Bokolooji and Bunaji cattle (Fasae and Olusesan(2015)
The range of fat within 3.78 – 5.71% of butterfat in the milk of grazing White Fulani
cows fed poultry waste- cassava peel based diet (Ndubueze et al., (2006). The variation
51
could be attributed to the environment and stage of lactation as the fat content of milk has
been found to vary considerably with the stage of lactation (O’Mahony, 1988).
The performed analyses indicated that the contents of total solids were 12.19% and
11.15% for the two production systems. The values were slightly lower than the ranges of
12.5 and 12.4% total solids for the milk of grazing Bunaji and Bokolooji cattle ( Fasae
and Olusesan2015). Ojedapo et al., (2014) however, reported lower levels of 10.48%
total solids while higher values of 15% was reported by Olorunsomo et al., (2014) in
Bunaji cows. Differences in nutrition and management could influence the variation of
percent total solids in milk across study (Matthewman, 1993).
Protein content of milk was significantly difference among the production system. The
finding in the current study inferior than the result reported by (Fasae and
Olusesan(2015)
The lactose contents of milk in this study were affected (p>0.05) by production
system. Lactose content in this study was significantly (p<0.05) lower in milk samples
collected from intensive system. The present finding higher than those reported by Fasae
and Olusesan(2015),however higher than that reported by Lingathurai et al., (2009).
The disparity in values may be due to system of management, environment and period of
study.
The performed analyses indicated that the content of protein was by 0.52% higher during the
traditional system and the content of fat was by 0.27% higher during the intensive system. Also,
milk collected in the intensive system had distinctly higher fat content. However, all differences
in the content of milk components observed between the studied systems were statistically
significant. The present finding disagrees with the result report by (Węglarz et al, 2008) . The
result indicate that best value of all milk component observed in traditional system ,this result is
confirmed by result reported by Seppala et al. (2006) who concluded that grazing at pasture is a
more profitable strategy for feeding dairy cows than either part time grazing or zero grazing. In
addition, it is generally accepted that grazing improves cow welfare because ‗free foraging‘ is
part of cows‘ natural behaviour.
According to the present results it seems that traditional pastoral system can provide
milk with better nutritional contents compared to the farming system. This could be
explained by the fact that natural pasture is more variable in plants and vegetations and
provides many varieties preferred by the cows.
51
5.3. Effect of interaction between parity order and production system on chemical
composition of cow milk
Finally, it is necessary to complete that the interaction of parity number and
production system had a significant effect on total solid and fat contents; on the other
hand this factor had no effect on solid non fat, protein and lactose contents.
In comparing the levels of milk constituents in the three parities a clear reduction was
observed in most of milk constituents from the first to fifth parity in both herds. The fat
content of traditional pasture and intensive system decreased significantly with advancing
parity.
Total solid content in cow milk decreased with advanced parities in both production
system, the average of the three parities was (12.19) and (11.15) for traditional and
intensive system respectively.
The content of solid non fat in cow milk decreased from 1st to advance parity in both
traditional pasture and Intensive system. The interactions were not significant (p<0.05)
for solid non fat. The results indicated that cow in third parity showed the highest value
of solid non fat (9.42, 8.06). Cow in fifth parity ranked third in traditional and intensive
system.
Crude protein content of cow milk under traditional pasture ranged from (3.27% to
3.37%) and the average of the 3 parities was (3.34 %), while it ranged from (2.70% to
2.83%) with (2.82%) in cow milk under farming system. As can be observed there was
no significant difference in protein content of cow milk from the two raising systems and
there was a slight reduction in protein content in advance parity of both systems. Best
value of protein for traditional system noticed in cow from third parity (3.38). Intensive
system followed the same sequence of traditional system.
The interaction was not significantly (p < 0.05) difference for lactose of cow milk.
Cow in third parity had the highest value for lactose, while cow in fifth parity revealed
the lowest value of lactose in both production systems.
52
Conclusion
In general, many factors besides nutrition and management can influence milk yield
and composition. This is an important point to remember when evaluating the milk
quality and in the improvement of milk yield and composition. The present study
emphasizes that the variations in cow milk composition could be attributed to factors
such as parity order and production system.
* The results of the study showed that parity significantly affects the fat and total solid
compositions. Cows in higher parities mainly third parity have higher values for solid non
fat, protein and lactose when compared to those in lower parities. Therefore, parity could
also be an important factor to be considered during the assessment and improvement of
milk quality in cows.
* The result indicated that production system had affected significantly for all parameter
except fat. The highest content of total solid, solid non fat, protein and lactose were
recorded in traditional system. Therefore, factors that cause variation in milk composition
should be taken into account when nutritional and technological aspects of cow milk are
evaluated.
Suggestions for future work
1/ determination of nutritive value of cow milk needs continuous trials to investigate the
effects of breed differences, stage of lactation and seasonal changes on milk composition.
2/ it is highly required to investigate and assess precisely the quality control of cow milk
including its vitamins, minerals, Amino acid profile ,fatty acid profile and microbial load
and factors affecting it.
3/ An enlightenment program on factors effect milk components (production system and
feeding) within the community will enhance the production milk with better nutritional
contents among the agro-pastoralists.
4/ interventions to improve the production practices through better management of cows
and their milk are needed.
53
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