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A STUDY ON THE PATHOGENESIS OF YOLKRETENTION IN BROILER CHICKS

Kashif Aziz Khan, Shakil Akhtar Khan, Shahnaz Hamid, Asim Aslam,Masood Rabbani

To cite this version:Kashif Aziz Khan, Shakil Akhtar Khan, Shahnaz Hamid, Asim Aslam, Masood Rabbani. A STUDYON THE PATHOGENESIS OF YOLK RETENTION IN BROILER CHICKS. Pakistan VeterinaryJournal, 2002, 22 (4), pp.175-180. �hal-00165844�

Pakistan Vêt. ./., 22(4): 2002

A STUDY ON THE PATHOGENESIS OF YOLK RETENTION IN BROILER CHICKS

Kashif Azi/ Khan. Shakeel Akhtar Khan. Shahnaz Hamid2 . Asim Aslam and Masood Rabbani 1

Department of Puilmlog\: 'Department of Microbiology,Universilv of Veterinarv and Animal Sciences, Lahore

"PCSIR Laboratories Complex. Lahore, Pakistan

ABSTRACT

The présent project was designed to identify thé factors responsible for yolk rétention in broiler chicks.l:our di l ieront expcrimonts were conducted to tlnd ont thé effect of four factors (expérimental yolk sacinfection wi th Escherichia culi, off-feed period between hatching and housing. first feeding time in thépoultry house and type of in i t i a l feed) on yolk absorption. Results of thèse experiments showed thatyolk sac infection with E. coli led to decrease in rate of yolk absorption. Moisture and proteinpercentage was increased in infected yolk but fat percentage was not affected by yolk sac infection. Onthé othcr hand, post hatch starvation due to delay in housing and delay in first feeding did not affectrate of yolk absorption. Moisture percentage was not affected \vh i l e fat absorption increased andprotein absorption decreased due to fasting. Il was also observed that feeding ground corn in early lifeof chick led to slow absorption of yolk contents as compared to feeding commercial starter ration and2% sugar solution. Yolk composition was not affected by feeding commercial starter ration, groundcorn and 2% sugar solution in early life of chick. It is conclude that expérimental infect ion with E. coliand ground corn as i n i t i a l feed leads to slow absorption of yolk sac in young broiler chicks.

Kcy words: Yolk rétention, yolk absorption, yolk sac infection, starvation. i n i t i a l feed. broiler chicks

INTRODUCTION MATERIALS AND METHODS

The raie of weight gain by broilers liassubstant ia l ly increased dur ing thé last few décades.Consequently. slaughter âge lias decreased such that théf ina l carcass weight, attained at \2 weeks of âge in théearly 1960s. now occurs by 6 weeks. This trend isc o n t i n u i n g and emphasizes thé importance of early life ofbroilers. This is very crucial period. as losses in first 2weeks of l i fe account for 30-50% of total mortality. Majorproblems dur ing this period are omphali t is , brooderpneumonia , avian encephalomyelitis. spiking mortality.dehydration, ammonia burns and pul lorum disease(Charlton. 1996). Omphal i t i s is thé inflammation of naveland yolk sac and it is thé commonest cause of early chickmortality in Pakistan (Anjum, 1997).

Whcn thé chick émerges from it's shell . yolk notu t i l i zed dur ing incubation is présent in yolk sac as anextension of small intestine. This residual yolk is absorbedduring first week of l i fe . Sometimes its rétention occursdue to certain factors. Présence of fat and water in yolkfavor thé bacterial growth which may lead to yolk sacinfect ion (Anonymous, 2000).

Présent project was designed to ident i fy théfactors responsible for yolk rétention in broiler chicks.This study w i l l hopeful ly help to understand thépathogenesis of yolk rétent ion, which w i l l contribute tocontrol earlv chick mortal i ty in broiler flocks.

Four experiments with variable treatments wereconducted but in a i l experiments. thé samè expérimentalparameters were studied.

Expcrinicnt No. 1Effecl of expérimental yolk sac infection

Escherichia coli on yolk absorption was studied.bv

Préparation of inoculuni (Escherichia coli)The isolation of a pathogenic strain of E. coli was

doue from thé diseased bird. The isolated organisms wereidentified on thé basis of their cul tura l , morphological andstaining characteristics, sugar fermentation andbiochemical reactions, as described by Buxton and Fraser(1977), Rehman et ul. (1996) and J a l i l and Das (2001).Pathogenicity was ascertained by thé method described byLee and Arp (1998). Viable count of thé isolate wasdetermined by plate count method (Collins et al., 1995).

Expérimental designForty llve. day-old broiler chicks were procured

from local hatchorj and 5 chicks were slaughtered to findont in i t ia l yolk sac weight on day-1 (before thé start ofexperiment). Remain ing chicks were distributed into twogroups A and B hav ing 20 chicks each. Chicks in group Areceived no bacteria (control) and 0.1 ml of stérile brothwas injected per bird into yolk sac of thèse chicks on day-

175

176 l'a../., 22(4/. 2002

I of thé experiment. Chicks of group B received E. colibroth inoculations (0.1 ml of thé broth per bird containingI 0 1 c . f .u /ml) into thé yolk sac (treatment) on day-l of théexperiment (Kloryga, 1986).

Experiment No. 2Kffect of off-teed period between hatching and

housing on yolk absorption was studied.

Expérimental designFï f tv . da\-old broi ler chicks vvere procured IVoin

local hatchery and 5 chicks vvere slaughtered to find onti n i t i a l yolk sac vveight on day-l (betbre thé start of théexperiment). Remaining chicks vvere distributed into 3groups A, B and C. having 15 chicks each.Chicks in group A vvere housed 24 hours afterhatching, so that off-teed period was 24 hours.Chicks in group B vvere housed 48 hours afterhatching, so that off-teed period was 48 hours.Chicks in group C vvere housed 72 hours afterhatching, so that off-feed period was 72 hours.

Experiment No. 3Rffect of flrst feeding time in thé poultry house

on yolk absorption was studied.

Expérimental designl ' i f ty , day-old broiler chicks vvere procured froin

local hatchery and 5 chicks vvere slaughtered to find onti n i t i a l yolk sac vveight on day-l (betbre thé start of théexperiment) . Rema in ing chicks vvere distr ibuted into 3groups A. B and C, having 15 chicks each.Chicks in group A were offered feed and waterimmedia te ly after arr ivai in shed.Chicks in group B were offered water immédiate!)after a r r iva i in shed vvh i l e feeding was delayed for 24hours.Chicks in group C vvere offered water immediate l )after arrivai in shed v v h i l e feeding was delayed for 48hours.

Evpei iment No. 4Effect of type of

was studied.feed on yolk absorption

hours tbl lovved by commercial starter ration.Chicks in group C were offered vvith 2% sugar solutionfor first 24 hours followed by commercial starterrat ion.

Sampling i l avsFive chicks from each group vvere sampled after

slaughtering on day-3, 5 and 7 of each experiment.

Expérimental parametersBody \veiglit: each bird was weighed betbre slaughtering.Yolk weight: thé unabsorbed yolk was removed andweighed.Yolk sac/body weight ratio: yolk sac/body weight ratiowas calculated by fol lowing formula:

Yolk sac vveightyolk sac/body vveight ratio^ x 100

Bodv weiiiht

Estimated yolk absorption: Estimated yolk absorptionwas calculated by thé following formula (Bierer andEleazer. 1965):

Mcan yolk sac Yolk sac weightvveight on day-l - on sampling day

Estimated yolk = x 100absorption Mean yolk sac weight on day-l

Analysis of yolk: Différent yolk contents (moisture, fatand protein) of each group vvere détenu ined. Moisture wasdetermined by drying thé sample in oven (Brammel,1984). fat by acid hydrolysis method and protein byKjeldahFs method (Vogel, 1961 ).

Slatistical analysisData thus collected were anaKzed s ta t is t ical ly by

applying unpaired 'f-test and one-way analysis of variance(ANOVA) and least significant différence (LSD) test wasused for means comparison of significant effects (Steelandïorrie. 1982).

RESULTS AND DISCUSSION

Expérimental designFifty. day-old broiler chicks were procured from

local hatchery and 5 chicks were slaughtered to find outi n i t i a l yolk sac vveight on day-l (betbre thé start of théexper iment) . Remain ing chicks were distributed into 3groups A. B and C, having 15 chicks each.Chicks in group A were fed vvith thé commercialstarter rat ion immediately after their arr ivai in théshed.Chicks in group B were fed ground corn for first 24

'I lie birds of group B infected v v i t h E. coli mexperiment No. 1 shovved thé fol lowing type ofsymptoms: drovvsiness. dépression, off-feed and distendedabdomen. Out of thèse birds. one died on day-4. two diedon day-5 and one died on day-6 of thé experiment. Whenyolks vvere removed. it was observed that thé birdsinlected wilh E. coli were having larger yolks in theirabdomen (Fig . I ). Yolks were having yellovv brown colourand vvatery consis tencv. Congestion of yolk sac bloodvessels was also observed. Resul ts of différentexperiments are shovvn in 'fables 1 to 4.

177 Pakistan i'cl. .)., 22(4): 2002

Y:)lk sac infectionYolk sac infec t ion is conimonest cause of early

chick morlal i ty in chickcn and most of bacteria casual lyinvolved are members of tlie family Enterobacteriaceae.Among thèse fachcric/iiti coli is niost important whoseinvolvenient is widely reported (Deeming, 1995; Rehnianci al., 1996: Anjum. 1997; Sharada cl «/., 1999;Anonynious . 2000). This organism was therefore selectedto infect thé \ o l k sac of dny-old broiler chicks in th i sstudv.

Fi». 1 : Enlargcd scptic yolk in situ

Body weight of infected chicks was s igni f icant lylouer thai i thé control chicks. Gross (1964) also observedreduced weight gain in yolk sac infection. This may bejust i f ied by thé tact that chicks were off-feed afterin fec t ion . Feed refusai was also reported in yolk sacinfec t ion by Bains (1979). It is tempting to speculate thatexpérimental E. coli infection adversely affects metabolicact ivi t ies of thé birds which ul t imately results inmalabsorption and reduced weight gain.

Il is also évident that weight of thé unabsorbedyolk in infected chicks was higher as compared to controlones. Deeming ( 1995) also reported that infected yolk sacsnere larger in mass than uninfected sacs from poults ofsaine aue. Yolk sac/bodv weight ratio was also hisjher and

estimated yolk absorption was lower in infected group.Thèse observations show that decrease in rate ofabsorption occurs due to yolk sac infection. This f inding isin l ine vvi th thé work reported by Sander el al. ( 1998). Theinfected yolks were having yellow brown appearance andwatery consistency. Similar observations were reported innatural infection by Jordan (1990), Sainsbury (1992) andAnjum (1997) and in expérimental infection by Bhatia clal. (1970) and Wi l l i am (1975). It can be thought that £.coli infection of yolk sac may cause denaturation of yolkingrédients which ul t imately affects the i r solubi l i ty andrate of transportation to blood stream. The changedpermeabil i ty of blood vessels under thé influence of thésaid bacterial infection can be attributed as another factorfor thé delayed yolk absorption.

Moisture content in yolk was higher for infectedchicks which could be explained by inflainmatorye.xudates secreted by cell l i n i n g of yolk sac in response tometabolic products and lysis of bacteria, as described byHarry (1957) . Fat content in yolk was not affectedappreciably by yolk sac in fec t ion . Protein absorption waslower in treatment group as compared to control group,possibil i ty due to al térat ion in protein structure or changein permeabili ty of yolk sac membrane.

Post-hatch starvationIt was observed that starvation, whether it was

due to delay of housing or delay in first feeding, causedsubstantial body weight loss in chicks. Wang et <://.( 1994)and Noy and Sklan (1999) also observed weight loss dueto starvation in early l i fe of chicks.

Yolk sac weight and estimated yolk absorptiondid not differ significantly between thé treatment groups.Yolk sac/body weight ratio was higher in chicks subjectedto 24-48 hours starvation after housing. This was not dueto yolk rétention but was due to loss in body weight. So itis concluded that yolk absorption is not affected by post-hatch starvation, whether due to delay in housing or delayin first feeding to chicks.

Thèse results corroborate w i t h those reported byChamblee cl ni. (1992) and Murakami et al. (1992), whoconcluded that offering feed on starvation did not affectdisappearance rate of yolk in abdomen. AI-Rawashdeh clcil. (1995) observed non-significant différence in yolk sacweight after subjecting day-old chicks to 5-day starvation.Baiao cl al. (1988) also reported that off-feed periodbetween hatching and housing did not affect yolkabsorption.

This f inding is not in agreement w i th thé findingsof Bierer and Eleazer (1965), Feher and Gyuru (1971) ,Moran and Reinhart (1980), Noy cl al. (1996) and Santosand Silversides (1996), who reported reduced yolk uptakein starved chicks whi le better u t i l iza t ion in fed chicks.Présent resuit is also against thé finding of Pisarski cl al.( 1998b). who showed efficient u t i l iza t ion of yolk contents

178 Pakistan Vêt. .].. 22(4): 2002

Table 1. Effect of expérimental yolk sac infection on body weight and différent yolk parameters

Samplingdays

Day-1Day-3

Day-5

Day-7

Croups

-

ABABAB

Bodyweight (g)

-55.7*47.1*70.5*52.3*124.6*65.0*

Yolk sacweight (g)

6.121.30*2.92*0.70*2.55*0.56*2.70*

Yolk sac:body weight

ratio-

2.33*6.21*1.30*4.89*0.45*4.16*

Estimated yolk -absorption (%)

-78.85*52.29*88.17*58.33*90.85*55.82*

Yolk compositionMoisture

(%)-

49.6358.6355.3659.9745.3961.10

Fat(% of DM)

-38.1739.7835.9534.1138.9038.26

Protein(% of DM)

-42.5044.8840.9442.3144.1945.81

*Significant différence (P<0.05)

Table 2. Effect of off-feed between hatching and housing on body weight and différent yolk parameters

Samplingdays

Day-1Day-3

Day-5

Day-7

Croups

.

ABCABCABC

Bodyweight (g)

-42. 1a

38.03

31 .5a

62.9d

55.8d

42. 3d

95.39

76.39

59.79

Yolk sacweight (g)

3.010.94a

0.79b

0.81e

0.63d

0.60e

0.65*0.459

0.40h

0.51'

Yolk sac:body weight

ratio-

2.25a

2.08b

2.58e

1.00d

1.08e

1.59de

0.479

0.53h

0.869h

Estimated yolk -absorption (%)

-68.57a

73.82b

72.96e

79.07d

80.33e

78.41f

85.059

86.78h

83.05'

Yolk compositionMoisture

(%)-

42.7340.4644.2441.2942.3239.7139.0838.6740.16

Fat(% of DM)

-43.3631.1729.2354.6142.4339.7139.0838.6740.16

Protein(% of DM)

-22.1739.3241.6424.0436.4546.9747.7357.5258.27

Values with différent superscripts in thé column differ significantly (P<0.05)

Table 3. Effect of first feeding time in thé poultry house on body weight and différent yolk parameters

Samplingdays

Day-1Day-3

Day-5

Day-7

Croups

-

ABCABCABC

Bodyweight (g)

-53. 3a

54.8b

53.9e

69.5d

71.5e

69.6f

105.69

101. 4h

101.9'

Yolk sacweight (g)

6.130.79a

2.59ab

0.84b

0.47d

1.18de

0.49e

0.209

0.659h

0.1 3h

Yolk sac:body weight

ratio-

1.48a

4.71ab

1.56b

0.66d

1.65de

0.71e

0.199

0.639h

0.12h

Estimated yolk -absorption (%)

87.0857.5786.2392.3680.6291.8796.7289.3797.87

Yolk compositionMoisture

(%)-

44.2648.9244.4352.2652.9752.5857.5256.5354.25

Fat(% of DM)

-45.6345.0246.6258.8152.1449.8351.9654.4852.71

Protein(% of DM)

-40.7545.0043.8144.7546.9449.1949.0045.5046.69

Values with différent superscripts in thé column differ significantly (P<0.05)

Table 4. Effect of type of initial feed on body weight and différent yolk parameters

Samplingdays

Day-1Day-3

Day-5

Day-7

Croups

-

ABCABCABC

Bodyweight (g)

.53.3a

54.8b

53.9e

69.5d

71.5e

69.6f

105.69

101. 4h *109.1'

Yolk sacweight (g)

6.130.79a

2.59ab

0.84b

0.47d

1.18de

0.49e

0.209

0.659h

0.1 3h

Yolk sac:body weight

ratio_

1.48a

4.71ab

1.56b

0.66d

1.65de

0.71e

0.199

0.639h

0.12h

Estimated yolk -absorption (%)

.87.08a

57.57ab

86.23b

92.36d

80.62de

91.87e

96.729

89.379h

97.87h

Yolk compositionMoisture

(%)

44.2648.9244.4352.2652.9752.5857.5256.5354.25

Fat(% of DM)

_

45.6345.0246.6258.8152.1449.8351.9654.4852.71

Protein(% of DM)

_

40.7545.0043.8144.7546.9449.1949.0045.5046.69

Values with différent superscripts in thé column differ significantly (P<0.05)

179 Pakistan Vêt. J., 22(4): 2002

in starved chicks.Percent moisture content in yolk did not show

any persistent trend due to post-hatch starvation but it isagainst thé évidence reported by Moran and Reinhart(1980), who showed better moisture mobilization fromyolk due to starvation. Feher and Gyuru (1972) alsoreported better résorption of water due to fasting in duckand goose.

Fat content was lower and proiein content washigher in starved chicks compared with fed chicks. Itindicates that starvation leads to better fat utilization whiledecreased protein absorption. Thèse observations are thésane as described by Moran and Reinhart (1980). Itindicates that chick has some ability for sélective nutrientwithdrawal from yolk or/and this might be due toincreased energy demand resulting from starvation.

Type of initial feedIt was observed that yolk sac weight and yolk

sac/body weight ratio was higher for thé group fed withground corn in first 24 hours of life while estimated yolkabsorption was lower for this group. So it is concludedthat feeding ground corn in early life leads to slowabsorption yolk of yolk sac. This finding was also reportedby Pisarski et al. (1998a). The slower yolk absorption maybe due to lack of protein-energy balance, since cornsupplies mainly energy and thé yolk contains massiveamount of dietary fat, though thé relative shortage ofprotein could be thé factor impairing utilization of energyfrom yolk. Moisture, fat and protein contents in yolk werenot affected by type of ini t ial feed.

It can be inferred that expérimental infection ofE. coli and type of init ial feed affect thé rate of yolkabsorption in young broiler chicks. The use of ground cornas ini t ia l feed can be assumed as a factor for slowing downyolk absorption. Further studies are required to establishthèse observations which are very essential for healthstatus of baby chicks.

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