Libro de Exposicion

Feed efficiency in swine

This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2011-68004-30336 from the USDA National Institute of Food and Agriculture

Feed efficiency in swine

edited by:

John F. Patience

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ISBN: 978-90-8686-202-3e-ISBN: 978-90-8686-756-1

DOI: 10.3920/978-90-8686-756-1

First published, 2012

Wageningen Academic Publishers The Netherlands, 2012

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned. Nothing from this publication may be translated, reproduced, stored in a computerised system or published in any form or in any manner, including electronic, mechanical, reprographic or photographic, without prior written permission from the publisher, Wageningen Academic Publishers, P.O. Box 220, 6700 AE Wageningen, the Netherlands, [email protected]

The individual contributions in this publication and any liabilities arising from them remain the responsibility of the authors.

The publisher is not responsible for possible damages, which could be a result of content derived from this publication.

Buy a print copy of this book atwww.WageningenAcademic.com/feedeff

Feed efficiency in swine 7

Table of contents

Preface 13

1. Herd management factors that influence whole herd feed efficiency 15A.M. Gaines, B.A. Peterson and O.F. Mendoza

Introduction 15Are we measuring feed conversion correctly? 16How do we measure ourselves over time? 17Is it time to shift our thinking? 20What is the best way to measure feed efficiency in the sow herd? 20Factors in a production system that could impact whole herd feed efficiency 23Sow replacement rate 23Timing of mortality 24Impact of birth weight on feed efficiency 26The effects of weaning weight on feed efficiency 28Harvest weight 29Pig removal strategies at marketing 31Floor and feeder space impacts on feed efficiency 32Conclusion 35References 36

2. Feeding and barn management strategies that maximize feed efficiency 41M.D. Tokach, R.D. Goodband, J.M. DeRouchey, S.S. Dritz and J.L. Nelssen

Introduction 41Prior to entry 42Loading the barn 46Daily chores 48Unloading the barn 55Conclusions 58References 59

3. Liquid feeding corn-based diets to growing pigs: practical considerations and use of co-products 63C.F.M. de Lange and C.H. Zhu

Introduction 63Design of liquid feeding systems 64Liquid feeding practices 66Effects of liquid feeding corn-based feeds on growth performance and carcass characteristics 68Use of liquid co-products: corn distillers solubles and corn steep water 71Use of dry high-fiber co-products: wheat shorts and dried distillers grains with solubles 75Conclusions and implications 76Acknowledgements 78References 78

8 Feed efficiency in swine

Table of contents

4. Amino acid nutrition and feed efficiency 81C.F.M. de Lange, C.L. Levesque and B.J. Kerr

Introduction 81Whole body protein deposition and pig growth performance 82Biology of amino acid utilization in growing pigs 84Effect of between-animal variability on optimum dietary amino acid levels for groups of pigs 88Implications of phase-feeding and compensatory growth for establishing optimum dietary amino acid levels 90NRC approach to estimating amino acid requirements of growing-finishing pigs 93Conclusions and implications 97References 98

5. The influence of dietary energy on feed efficiency in grow-finish swine 101J.F. Patience

Introduction 101Defining and expressing feed efficiency 102Definition of dietary energy 105Dietary sources of energy 108Energy systems 110Dietary energy used for maintenance and for gain 116Daily energy intake 120Other considerations 122Practical approaches to improving feed efficiency 122Conclusion and implications 125References 125

6. Feed processing to maximize feed efficiency 131C.R. Stark

Introduction 131Ingredient selection and least cost formulation 132Feed manufacturing quality assurance 135Feed manufacturing 138Feed ordering and delivery 148Conclusion 149References 149

7. The genetic and biological basis of residual feed intake as a measure of feed efficiency 153J.M. Young and J.C.M. Dekkers

Introduction 153The genetic basis of residual feed intake 154Physiological basis of residual feed intake 154Selection experiment in Yorkshire pigs to create lines divergent in residual feed intake 156Conclusions 163Acknowledgements 163References 164


Table of contents

8. Pig breeding for improved feed efficiency 167P.W. Knap and L. Wang

Feed efficiency: past developments 167Feed efficiency: biological backgrounds 169Genetic change in production traits and feed efficiency 173Breeding for improved feed efficiency 175Implications 178References 179

9. Effect of climatic environment on feed efficiency in swine 183D. Renaudeau, H. Gilbert, and J. Noblet

Introduction 183General aspects 184Consequences of thermal stress on feed efficiency 187Strategies for alleviating the effects of thermal stress on feed efficiency 196Conclusion 203References 205

10. Fueling the immune response: whats the cost? 211R.W. Johnson

Introduction 211Relationship between disease and growth performance 212How does the immune system sense the pathogenic environment? 215How does the immune system affect growth? 218What does it cost to nourish the immune response? 220Acknowledgements 220References 220

11. Influence of health on feed efficiency 225S.S. Dritz

Introduction 225Direct effects of mortality 226Chronic immune stimulation 227Production responses to in-feed antimicrobials in multi-site production 228Field data 229Future advances 234Conclusion 235References 235

12. Physiology of feed efficiency in the pig: emphasis on the gastrointestinal tract and specific dietary examples 239J.R. Pluske

Introduction 239Secretions from the lactating sow and piglet growth efficiency 239Growth factors in colostrum and milk 242Changes in feed efficiency associated with weaning 243


Table of contents

Relationships between dietary protein source and post-weaning diarrhea 247ZnO as a growth-promoting compound to enhance feed efficiency after weaning 250Conclusions 251References 253

13. Emerging technologies with the potential to improve feed efficiency in swine 259F.R. Dunshea

Introduction 259Porcine somatotropin 260Ractopamine 261Cysteamine 263Chromium 264Betaine 266Dietary neuroleptics 266Immunization against GnRF 268Conclusions 269References 269


Preface

The world as we know it is changing at an accelerated pace. Continued growth of the human population will put increasing pressure on feed supplies and food production. Coincident with a rising population is a growing demand for pork, as the standard of living rises in many parts of the world. Meeting this demand will be a challenge that farmers must face head-on. Pork producers face other challenges as they adopt new technologies to produce more with less. Unprecedented and unexpected growth of the grain biofuels sector in the past decade has upset the traditional balance of supply and demand in the grain economy. It will take some time for a new equilibrium to be reached.

The other competitor for feed resources human food will also expand as the human population grows. Nevertheless, the global pork industry has co-existed with the human food complex for some time, so although it represents another major user of potential feed resources, it is not a new or unfamiliar competitor.

Other trends, such as competition from other meat sources like poultry, a decline in arable land in many historically important agricultural regions and uncertainty about the future of irrigation in arid regions will also place greater demands on the pig industry to use feed resources more effectively. It was in this context that Feed efficiency in swine was born.

This book evolved from the International Conference on Feed Efficiency in Swine held in November, 2011. At that event, the speakers were charged with presenting the newest and most current information available on feed efficiency in swine, covering everything from daily barn management to the adoption of new technologies. This book has the same objective as that conference and uses the speakers as its authors.

By bringing together authors with a wide array of backgrounds and roles in the pig industry, the chapters in this book represent a similar diversity, looking at feed efficiency from perspectives in the barn as well as in the laboratory. Feed efficiency in swine covers a broad spectrum of scientific disciplines, including nutrition, genetics, veterinary medicine, physiology, feed processing and many others. The result is a unique book that provides the reader with an abundance of information on a variety of approaches to maximizing feed efficiency in the pork industry today.

I want to thank the authors, each of whom enthusiastically accepted the challenge to address their topic thoroughly and proficiently. They validated their selection as authors by the very high quality of the chapters they submitted. I also want to thank Abby Anderson, Holly Schuler and Julie Roberts for their editorial assistance, and convey particular appreciation for the professional assistance provided by Mike Jacobs and his staff at Wageningen Academic Publishers. The quality of this book attests to their efforts.

Finally, I want to acknowledge that this book project was supported by Agriculture and Food Research Initiative Competitive Grant No. 2011-68004-30336 from the USDA National Institute of Food and Agriculture.

J.F. Patience, editor

15

1. Herd management factors that influence whole herd feed

efficiency

A.M. Gaines, B.A. Peterson and O.F. MendozaThe Maschhoffs, LLC, 7475 State Route 127, Carlyle, IL 62231, USA; [email protected]

Abstract

This chapter provides a broad overview of herd management factors that influence whole herd feed efficiency. As producers continue to look for ways to manage high feed costs, a significant economic opportunity exists to narrow the gap between actual performance and genetic potential by focusing on the impact of various herd management factors that could be impacting feed efficiency. Optimization of these factors will be system dependent, and will rely heavily on gathering and interpreting information to make informed decisions, which will ultimately make the swine industry more efficient and competitive in the global protein production sector. In addition to examining herd management factors that influence whole herd feed efficiency, we will attempt to challenge old paradigms on how to measure feed efficiency within a production system.

Introduction

The typical measurement for feed efficiency is feed per unit live weight gain (Feed:Gain) also known as feed conversion rate. Because feed efficiency is the outcome of both feed intake and average daily gain, nutritionists tend to focus their attention on the individual factors that impact feed consumption and gain. An incomplete list of these individual factors would include dietary energy level, amino acid deficiency, feed availability or wastage, etc. Although these factors are important from a nutritionists point of view, one cannot dismiss other factors in a production system that perhaps influence feed efficiency to a greater extent including genetics, disease, environment, and management factors. These factors cannot be evaluated in isolation and must be considered when evaluating feed efficiency within a production system.

Given todays high feed cost environment, there has been considerable emphasis placed on feed efficiency. This is understandable given that feed inputs represent a significant portion of overall production costs and improving feed efficiency is one strategy to improve cost per unit gain. Traditionally, this has been done through changes in dietary energy level; however, given current energy costs there has been a shift to high fiber-low energy diets. This has been prompted by direct competition for the same feedstocks as the biofuels industry, which has increased the use of biofuel co-products such as dried distillers grains with soluble (DDGS) and other alternative ingredients to optimize feed costs. In general, these feedstocks have been found to be lower in energy as compared to corn. As a result, feed efficiency has inherently gotten worse with diet formulations utilizing these ingredients.

With the increased use of high fiber diets, there is the potential to reduce carcass yield. This is well documented in the literature as it relates to feeding high levels of DDGS continuously in the

J.F. Patience (ed.), Feed efficiency in swine, DOI 10.3920/978-90-8686-756-1_1, Wageningen Academic Publishers 2012


A.M. Gaines, B.A. Peterson and O.F. Mendoza

finishing phase of growth (Stein and Shurson, 2009). As it relates to feed efficiency, this may be of economic consequence given the fact that most finishing pigs are sold on a carcass basis. Thus, a reduction in carcass yield inherently increases the feed per unit of carcass gain. Due to the cost impact of feed efficiency loss, it is imperative that one considers the reduction in carcass yield when feeding high fiber diets.

The purpose of this chapter is to challenge old paradigms regarding the measurement of feed efficiency given todays high feed cost environment, while considering dietary energy levels, feedstocks being utilized, and how pigs are being sold into the marketplace. In addition, this chapter will examine factors in a production system beyond nutrition that may impact feed efficiency with an attempt to quantify the magnitude of these factors on whole herd feed conversion.

Are we measuring feed conversion correctly?

As previously indicated, the typical measurement for feed efficiency is feed per unit gain being expressed on a live weight basis. Given the fact that most pigs are sold on a carcass basis, there is a strong argument to measure feed conversion on a carcass basis as well. This is particularly true when differences exist between live and carcass gain measurements, which can be the case when feeding high fiber diets. To illustrate this point, we can look at the data collected in our production system where pigs were fed varying levels of DDGS (Table 1). For example, if one looks at live feed conversion expressed as G:F ratio, there was a significant difference among the treatment groups. As compared to the 0% DDGS level, the G:F ratio was 1.3 and 2.1% lower for pigs fed 15 and 30% DDGS, respectively. However, if one considers the reduction in carcass yield with increasing DDGS level, the differences are even more apparent. As compared to the 0% DDGS level, the G:F ratio was 2.1 and 3.8% lower for pigs fed 15 and 30% DDGS, respectively. In this example, depending on whether one utilizes live vs. carcass feed conversion, there is a

Table 1. Impact of DDGS level on feed efficiency from weaning to market (The Maschhoffs, LLC (Trial# 200918)).

Item DDGS (%) SEM P-value

0% 15% 30%

Start weight (kg) 5.86 5.86 5.81 0.05 NSEnd weight (kg) 123.6 123.7 124.2 0.32 NSGain:Feed1 0.378a 0.373b 0.370b 0.002


1. Herd management factors that influence whole herd feed efficiency

significant impact on the economic decisions within a production system as it relates to the nutrition program. Thus, when feeding high fiber diets, one should consider the potential impact on carcass yield and the indirect impact on carcass feed efficiency.

How do we measure ourselves over time?

As we look to measure feed efficiency over time, it is important to recognize changes that could impact this metric. Some of the changes we have seen in recent years are changes in dietary energy level, weaning age, market weight, and implementation of feed processing technologies. If one looks at energy level, there has been a significant decline in dietary energy levels over the last several years due to rising feed costs and feedstocks being utilized. The industry has also moved to older wean age pigs in an effort to place heavier pigs at the time of weaning due to the improvements in growth performance and livability (Dritz et al., 1996; Main et al., 2004). Additionally, industry harvest weights have seen an upward trend for the past several years. This has made economic sense because the additional revenue obtained for each incremental unit of weight was almost always greater than the incremental increase in production costs. In an effort to manage high feed costs, there has been renewed interest in feed processing technologies by production systems due to the observable improvements in feed efficiency (Skoch et al., 1983; Stark et al., 1994; Wondra et al., 1995). Taken together, these changes aimed at system optimization make interpretation of production and financial records difficult over time, particularly for a metric such as feed efficiency. Thus, it is important to attempt to account for these changes to make better sense of production and financial data.

We know that feed efficiency will be influenced by the energy level of the diet, entry and exit weight of the pigs, and whether the diet is further processed. Adjustment factors can be utilized to account for these factors and their impact on feed efficiency. Equations have been generated to allow for feed efficiency adjustments (Goodband et al., 2008). Perhaps the simplest adjustment as it pertains to these equations is to account for differences in entry and exit weight of a group of pigs. An example of this type of equation is shown in Equation 1, where adjustments are made to entry and exit weight (Goodband et al., 2008).

Adjusted Feed:Gain = observed Feed:Gain + (50 entry weight) 0.005 + + (250 market weight) 0.005 (1)

This equation adjusts all groups to a common entry weight of 50 lbs and an exit weight of 250 lbs. The multiplier of 0.005 represents the slope of the equation describing live feed conversion vs. body weight on corn-soybean meal based diets with ~5% supplemental fat. The data shown in Table 2 represents an example of adjusting feeder to finisher feed conversion in closeout data using this equation. Feed conversion appears to be relatively similar between the growers in this example. However, when feed conversion is adjusted to account for entry and exit weights, grower 1 has the better G:F. The better adjusted feed conversion rate for grower 1 is due to the heavier pig weights at entry and exit. Further adjustments can be made to account for different grain sources, dietary energy levels, and pelleted or meal diets as shown in Equation 2 (Goodband et al., 2008).



observed Feed:Gain + (50 entry wt) 0.005 + (250 market weight) 0.005Adjusted Feed:Gain = (2) [Grain factor (fat level 2)) (1 pellet factor)]Grain factor = 1 for corn, 1.02 for milo, 1.18 for barley, and 1.07 for wheatPellet factor = the % improvement in feed efficiency due to pelleting (generally 4 to 6%)

The adjustment for energy level uses an adjustment for grain source and fat level in the diet [grain factor (fat level 2)], where the grain factor is 1 for corn and fat level is the percent fat in the diet. This equation does assume a 2% improvement in Feed:Gain for every 1% added fat. The adjustment for pelleting is (1 pellet factor), where the pellet factor is the percentage improvement in feed efficiency due to pelleting. Based on the aforementioned empirical data, this would generally be 4 to 6%. Another equation that we have utilized in our system is proposed in Equation 3.

Adjusted F:G = (Observed F:G + (Standardized sw Actual sw) Slope estimate + (Standardized fw Actual fw) Slope estimate ((Standardized el Actual el)/ Standardized el) Observed F:G) (3)

F:G = Feed:Gain ratio; sw = start weight; fw = final weight; el = energy level

An example using this equation is shown in Figure 4 and utilizes a similar slope estimate as described previously. The importance of understanding the pigs growth response to dietary energy within your own system should be emphasized, as it will change the slope estimate. Similar to the previous equation, further adjustments can be made to account for other factors such as pelleting, grind size, mortality, etc.

Another factor to consider when adjusting feed efficiency from a nutritional point of view is to account for differences in mortality, especially in a case where production systems have experienced high mortality rates due to novel disease introduction. When making this type of adjustment, it is critical to know the feed conversion impact for each percentage increase in mortality. In Figure 1, assuming a mid-point mortality during the finishing phase of growth, we have attempted to quantify

Table 2. Finishing closeout-comparison based on 2007 data (Goodband et al., 2008)1.

Item Grower 1 Grower 2

Weight in (kg) 25.9 20.4Weight out (kg) 123.4 120.2Mortality (%) 4.9 3.7Average daily gain (kg) 0.853 0.848G:F 0.352 0.350Adjusted G:F 0.376 0.357

1 Closeouts are adjusted for initial and final weight only.



the impact on feed conversion at different marketing end weights. It is important to note that this type of mortality adjustment to feed conversion does not account for the disease impact and assumes the mortality occurred during the mid-point of the growth period. The data in Table 3 represents an example of adjusting feeder to finisher feed conversion for mortality differences in closeout data. At the mortality rates incurred by grower 1 and 2, the adjustments in G:F were 1.6 and 1.1%, respectively.

Box 1. Example of feed efficiency adjustments standardized for energy level and weight based on Equation 3.

Example:

Observed Feed:Gain = 3.00 Actual start weight = 45 lbs Actual end weight = 250 lbs Actual energy level = 1,500 kcal/lb ME

What is the adjusted Feed:Gain if we standardize for energy level and weight?

2.71 = (3.00 + (50 45) 0.005 + (250 275) 0.005 ((1,600 1,500) / 1,600) 3.00)

Figure 1. Feed efficiency impact for each percentage increase in mortality for feeder to finish pigs at varying final live body weights.11 Assuming the mortality occurred during the mid-point of the growth phase (i.e. 60 lbs to final live body weight).

y = 0.00000801x + 0.00829289 R2 = 1.00000000

0.0098 0.0099 0.0100 0.0101 0.0102 0.0103 0.0104 0.0105 0.0106 0.0107 0.0108

200 220 240 260 280 300 320

Feed

con

vers

ion

rate

Final body weight (lbs)

FTF adjusted for mortality (live)



Is it time to shift our thinking?

Unless something changes to energy costs in the foreseeable future, it appears that dietary energy levels will continue to decline. As previously discussed, this makes it difficult to interpret feed conversion data over time as it is confounded due to energy level among other factors. Adjustment factors can be used to account for these differences in energy level over time, but perhaps it is time to shift our thinking more dramatically in regards to measuring feed efficiency. Instead of measuring feed conversion, there is a case to simply utilize caloric efficiency in its place as a measurement of feed efficiency. This metric considers the amount of calories required per unit of gain, regardless of the dietary energy level fed. In Figure 2, we compare caloric efficiency vs. feed efficiency for pigs expressed on a carcass basis during the grow-finish period. As one evaluates whether to utilize this metric, it will require an understanding of how the pig responds to dietary energy to establish defined targets for the various production phases. Furthermore, it will be system specific depending on the energy system utilized. To account for other factors (i.e. feed processing), adjustment factors may also be necessary.

What is the best way to measure feed efficiency in the sow herd?

A common practice for sow farms is to measure sow feed per year with a typical target of 1,000 to 1,090 kg/sow/year; however, this metric is not a good indicator of sow herd feed efficiency. Thus, increasingly more production systems are utilizing sow feed per weaned pig produced, with targets based on sow productivity. For example, to achieve 36 kg of sow feed per weaned pig, a sow farm would need to be at 29 pigs/sow/year (P/S/Y) or better, assuming diets are fed in meal form, as shown in Figure 3. To take this one step further, one could measure sow feed per unit of live weight produced as shown in Figure 4. This, of course, requires the sow farm to weigh the pigs at the time of weaning. If a production system wants to express this on a carcass feed efficiency basis, a yield factor on the wean pig would need to be applied (i.e. 65% of live weight).

Table 3. Finishing closeout-comparison (2007 data) with mortality adjustment (Goodband et al., 2008)1.

Item Grower 1 Grower 2

Weight in (kg) 25.9 20.4Weight out (kg) 123.4 120.2Mortality (%) 4.9 3.7Average daily gain (kg) 0.853 0.848G:F 0.352 0.350Adjusted G:F 0.376 0.357Mortality adjusted G:F2 0.382 0.361

1 Closeouts are adjusted for initial and final weight only.2 Adjustment is based on mortality impact on G:F.



Figure 2. Caloric efficiency vs. feed efficiency expressed on a carcass basis.11 Source data: PIC ES 051-Tech Memo. 344; cumulative data from feeder pig wt (34.7 kg live body weight); 3,437 kcal/kg NRC ME; 76% yield factor.

13,159 13,612

14,154 14,606

15,149 15,692

3.83 3.96 4.12 4.25

4.41 4.57

11,500

12,000

12,500

13,000

13,500

14,000

14,500

15,000

15,500

16,000

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

193 204 214 225 235 245

kcal

/kg

F/G

Carcass end weight (lbs)

PIC energy eff. PIC FCR

Figure 3. Impact of sow productivity on sow feed per wean pig.11 Assuming 1,052 kg annual sow feed usage (i.e. gestation @ 2.27 kg/day; lactation 5.90 kg/day) and litter/sow/year = 2.45.

0 5

10 15 20 25 30 35 40 45 50

25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30Pigs/sow/year

Sow

feed

per

wea

n pi

g (k

g)



When examining whole herd feed efficiency, the productivity of the sow herd directly determines the number of pigs that sow feed use and costs can be spread over. Whole herd feed efficiency for the sow can be measured using sow feed per pig marketed to include gilt development and boar feed. As shown in Figure 5, sow productivity moderately impacts whole herd feed carcass feed efficiency. For example, increasing P/S/Y on a given farm from 25 to 30 P/S/Y improves whole herd carcass feed efficiency by 1.7%. Although this seems to be a small improvement given a 20% increase in sow productivity, one needs to be mindful that sow feed only represents 10 to 12% of whole herd feed efficiency.

Figure 4. Sow feed per wean kilograms produced (live weight basis).11 Assuming 1,052 kg annual sow feed usage (i.e. gestation @ 2.27 kg/day; lactation 5.90 kg/day) and litter/sow/year = 2.45.

0

1

2

3

4

5

6

7

8

25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

Pigs/sow/year

Sow

feed

per

wea

n ki

logr

ams

prod

uced

Figure 5. Impact of sow productivity on whole herd carcass feed efficiency, assuming 1,052 kg annual sow feed usage plus gilt development feed (i.e. 152 kg/sow) and market weight of 90 kg carcass weight.

3.92 3.94 3.96 3.98 4.00 4.02 4.04 4.06

25 25.5 26 26.5 27 27.5 28 28.5 29 29.5 30

Feed

con

vers

ion

rate

Pigs/sow/year

Whole herd carcass FCR



Factors in a production system that could impact whole herd feed efficiency

Modern commercial pigs in production systems throughout the world have a much improved potential for growth and a much better ability to convert feed to carcass gain than their past counterparts. As it relates to improvements in feed efficiency, there has been continuous genetic selection aimed primarily at increasing lean deposition while reducing the level of fat in the body. Despite the genetic capability of todays pig, most production systems struggle to capture the full genetic potential of their animals. For example, we have found in our research facilities that the energetic efficiency potential can be ~8% better than pigs reared under commercial conditions (Figure 6). Interestingly, our research facilities are akin to those used in the rest of our production system. Thus, an economic opportunity exists to narrow the gap between actual and potential performance. In the following subsections, we will take a closer look at some factors in a production system that should be considered when examining whole herd feed efficiency.

Sow replacement rate

A high sow replacement rate has a direct effect on whole herd feed efficiency due to the number of gilts needed to maintain mating volume. When producers retain more gilts to maintain mating volume, whole herd feed conversion inherently gets worse because of the higher herd feed consumption and (or) reduced output of pigs. Gilts generally have lower reproductive performance (i.e. total born and farrowing rate), which lowers the number of pigs weaned. Furthermore, mortality is typically higher for gilt vs. sow litters from birth to market as shown in Table 4 by Smits and Collins (2009). The lower survivability of gilt offspring is likely due to immune competence and their higher susceptibility to disease. Given what we know about the

Figure 6. Cumulative carcass energy/kg gain for pigs reared in a commercial vs. research environment, assuming PIC 337 Camborough pigs and actual entry weight of 22 kg carcass weight.

8,000

9,000

10,000

11,000

12,000

13,000

14,000

15,000

16,000

22.1 34.9 49.3 64.3 79.4 93.8 107.2 119.6 130.8

kcal

/kg

gain

Carcass end weight (kg)

Research Commercial



gilt and her offspring, lowering sow replacement rate will improve whole herd feed conversion, which is supported by Smits (2011) and shown in Table 5. These data compare two different sow farms with differing replacement rates (i.e. 65 vs. 40%). By lowering the replacement rate, herd feed conversion is improved by 2%. If one considers the direct effects of sow replacement with the indirect effects of a reduced proportion of gilt progeny in the herd, feed conversion is improved by 3%, which is shown in Table 6 (Smits, 2011). Taken together, management of the sow herd replacement rate clearly has direct and indirect effects on the performance of their progeny and consequently, on whole herd feed conversion.

Timing of mortality

Generally speaking, the focus on pig mortality has been centered on the period from farrowing to weaning, as it has been well established that losing pigs during this critical period will negatively affect the efficiency of a production system. It is during this period that the majority of the research has been carried out and the causes and strategies to mitigate mortality have been well defined. However, such is not the case during the grow-finish period, as there is limited data to bring perspective to the specific effect(s) of pig mortality throughout the grow-finish period. Nevertheless, the timing at which pig mortality occurs during the grow-finish period has a

Table 4. Differences between gilt and sow progeny (Smits and Collins, 2009).

Treatment Preweaning Weaner Grower Finisher

Progeny of gilts1 14.4% 5.6% 3.9% 6.7%Progeny of sows1 11.2% 2.7% 2.2% 4.8%P-value 2 5.2 (0.022) 2 10.9 (0.001) 2 4.2 (0.041) 2 2.5 (0.116)

1 Differences between gilt and sow (parity 3-7) progeny in respect of mortality and removal for ill thrift expressed as a percentage of the number of pigs at the start of each growth phase.

Table 5. Predicted response in annual reproductive output and herd feed conversion efficiency (Smits, 2011).

Item1 Pigs weaned

Pigs mated

Pigs born alive

Progeny sold

Cull carcass weight (t)

Progeny carcass weight (t)

HFC2

Scenario 1 18,720 2,349 21,767 15,420 127.2 1,170.6 3.86Scenario 2 18,720 2,176 21,273 15,731 96.7 1,194.2 3.78

1 Scenario 1: 65% replacement rate, base production levels, 26% gilt matings, 82% farrowing rate, 11.3 born alive, 14% preweaning mortality, 17% breeder mortality, culled sow weight = 175 kg hot standard carcass weight. Scenario 2: 40% replacement rate, 14% gilt matings, 85% farrowing rate, 11.5 born alive, 12% preweaning mortality, 8% breeder mortality, culled sow weight = 210 kg cwt.2 HFC = herd feed conversion.



significant impact on efficiency of a production system, such that losing pigs at a heavier body weight has a bigger toll on production costs (Maes et al., 2001). In addition, as pigs die at heavier body weights, the feed conversion ratio will be impacted more negatively for every 1% increase in mortality, compared to pigs that die at a lighter body weight (Figure 7). Given the impact of pig mortality on herd feed efficiency it is imperative that production systems understand the timing and causative factors of the mortality in order to develop health management plans to minimize these losses.

Table 6. Predicted response in annual reproductive output and herd feed conversion efficiency (Smits, 2011).

Item1 Pigs weaned

Pigs mated

Pigs born alive

Progeny sold

Cull carcass weight (t)

Progeny carcass weight (t)

HFC2

Scenario 1 18,720 2,349 21,767 15,420 127.2 1,170.6 3.86Scenario 2 18,720 2,176 21,273 15,731 96.7 1,194.2 3.78Scenario 3 18,720 2,176 21,273 15,914 96.7 1,217.7 3.74

1 Scenario 1: 65% replacement rate, base production levels, 26% gilt farrowings, 82% farrowing rate, 11.3 born alive (gilts = 10.2, sows = 11.7), 14% preweaning mortality, 17% breeder mortality, culled sow weight = 175 kg cwt. Scenario 2: 40% replacement rate, 14% gilt farrowings, 85% farrowing rate, 11.5 born alive, 12% preweaning mortality, 89% weaned progeny from parity 2+ sows, 12% breeder mortality, culled sow weight = 210 kg cwt. Scenario 3: As for Scenario 2 plus an increase of 0.8 kg live weight at sale and a 0.05% reduction in weaner-grower mortality rate.2 HFC = herd feed conversion.

Figure 7. Impact of a 1% increase in mortality on feed conversion of pigs at different body weights, assuming actual entry weight of 27 kg live weight and market carcass weight of 127 kg.

0.005

0.011

0.017

52 77 102

Live body weight (kg)

Feed

:Gai

n



Impact of birth weight on feed efficiency

Variation in individual pigs ability to convert feed to body tissues is caused by multiple factors, some of which are environmental in nature and some genetically programmed. One such factor is the weight of the pig at birth. In all litter bearing species, variation exists between littermates in all phenotypic traits at birth, and possibly the most notable is body weight. Birth weight has been studied and reported on extensively in the literature and the reported effects on feed efficiency are variable.

While genetic diversity is a fact of nature, many environmental factors during the prenatal period can have a profound impact on the overall growth potential and body composition of a pig. A brief discussion of the prenatal environment and its impact on variation in birth body weight within and among litters is warranted to understand the causes and extent of variation that exists in pig birth weight. Birth weight is determined in utero as a direct result of fetal nutrition. Fetal nutrition can be affected by a variety of factors; however, when all else is held constant (sow nutrition, disease status, etc.), variation in birth weight within the litter remains. Fetal nutrition can be influenced by many factors other than the level and quality of feed that the sow consumes. The number of fetuses and the position of the fetus within the uterus also largely influence the level of nutrition that the individual fetus receives. It has been reported that as litter size increases, average birth weight decreases (Johnson et al., 1999), due to the effects of intrauterine crowding and the resultant increase in competition among the fetuses for maternal nutrients. It has been known for some time that intrauterine crowding impacts fetal growth rate (Dziuk, 1968), and the effect of crowding has been shown to manifest as early in gestation as day 30 as evidenced by the work of Foxcroft et al. (2006). This work reported a significant decrease in myogenesis at 30 days of gestation associated with higher levels of intrauterine crowding, which could result in lower capacity for lean growth during the pigs life. The effects of intrauterine crowding and fetal under-nutrition have the greatest effect on the smallest fetus in the uterus because the smallest fetuses generally have the least amount of placental surface area attachment within the uterus. This results in fewer nutrients from the sow being passed on to the smaller fetuses and therefore slower prenatal growth rates. Therefore, the effects of increased nutrient intake of the sow could have the greatest impact on the smallest fetuses, as the larger ones are already receiving adequate nutrition for growth and development. This theory is supported by the findings of Dwyer et al. (1994), who reported that increased sow nutrition during gestation was found to produce the greatest relative increase in body weight in the smallest fetuses. Genetic improvement in litter size has been quite successful and the result has been very large litters and highly productive sows. As shown in Figure 8, the impact these larger litters have on birth weight must also be considered in the production system economics equation, and genetic progress must provide for increased uterine capacity to avoid negative impacts on pig birth weight as litter sizes continue to increase.

A great deal of research has been completed studying the effects of birth weight on pig growth rate, feed intake, feed efficiency, and carcass characteristics. A vast majority of the studies have reported that light birth weight pigs have a lower post-weaning growth rate; however, the results for feed efficiency effects have been mixed. Multiple studies have reported a reduction in average daily gain in light birth weight pigs compared to heavy birth weight pigs as a result of lower feed intake with no impact on feed efficiency (Gondret et al., 2005; Quiniou et al., 2002; Wolter et al.,



2002a). In contrast, a number of studies have reported light birth weight pigs have poorer feed efficiency (Powell and Aberle, 1980; Gondret et al., 2006; Peterson, 2008) and Mroz et al. (1987) reported, after conducting digestibility research, that light birth weight pigs also utilized nutrients (i.e. energy, nitrogen, etc.) less efficiently than heavy birth weight pigs.

One possible explanation for the poorer feed efficiency observed in the literature is a reduction in the light birth weight pigs overall capacity for lean tissue accretion. Muscle fiber number has been found to decrease with birth weight in a number of studies (Nissen et al., 2003; Bee, 2004; Gondret et al., 2006). Handel and Stickland (1987) and Dwyer et al. (1994) reported that the number of primary muscle fibers was equal among pigs of different birth weights; however, the number of secondary fibers was found to be lower in lighter birth weight pigs. Secondary muscle fibers develop early in gestation, usually around day 25 to 30. As previously stated, the work of Foxcroft et al. (2006) reported a significant decrease in myogenesis during this time associated with intrauterine crowding, which would suggest that fetal under-nutrition is a possible cause of depressed secondary muscle fiber development. Since the number of muscle fibers in pigs is set at birth and subsequent muscle growth is a result of fiber hypertrophy, light birth weight pigs could therefore have lower capacity for total lean tissue growth resulting in the deposition of proportionally more adipose tissue than heavy birth weight pigs. This is further supported by the work of Peterson (2008) that suggested a decrease in fat free lean percentage in light birth weight pigs compared to heavy birth weight pigs at a common harvest weight (Figure9). These differences in carcass composition could ultimately result in poorer feed efficiency as adipose tissue is more energy dense than lean and thus requires more nutrients per unit of weight to accrete. It is well established that light birth weight pigs grow slower than their heavy birth weight counterparts (Peterson, 2008; Table 7). When considering overall efficiency of growth to a common body weight, light birth weight pigs will also undoubtedly be slightly less efficient due to the extra maintenance energy required during the added days of growth. Future research

Figure 8. Impact of pigs/sow/year on birth weight (Source: the Maschhoffs).

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

13.2 15.4 17.6 19.8 22.1 24.3 26.5 28.7 30.9 33.1 35.3 37.5 39.7 41.9

Birt

h w

eigh

t (kg

)

Pigs/sow/year



should be aimed at finding management strategies that either reduce or exploit this variation in birth weight in an effort to improve overall efficiency of production.

The effects of weaning weight on feed efficiency

The assertion that heavier pigs at weaning will grow faster and require fewer days to reach market weight has been supported in a number of studies (Boaz and Elsley, 1962; McConnell et al., 1987; Mahan and Lepine, 1991; Klindt, 2003). When considering the impact of weaning weight

Figure 9. Carcass fat-free lean percentage for heavy, medium, and light birth weight pigs (Peterson, 2008).

50

52

54

56

58

Car

cass

fat-f

ree

lean

per

cent

age

Heavy Medium Light

Table 7. Effect of birth weight and weaning weight on overall growth performance (Peterson, 2008).

Item Birth weight category Weaning weight category

Heavy Light SEM1 P-value Heavy Light SEM1 P-value

Body weight (kg)Birth 1.75a 1.31b 0.054 0.001 1.53 1.53 0.054 0.768Weaning 7.56a 6.71b 0.377 0.011 7.41 6.87 0.377 0.090Market 125.4 124.1 0.60 0.145 124.8 124.8 0.60 0.953

Weaning to marketAverage daily gain (g) 877a 844b 11.0 0.002 859 862 11.0 0.719Average daily feed intake (kg) 2.08 2.04 0.021 0.142 2.06 2.06 0.021 0.849Gain:Feed 0.422 0.415 0.0027 0.056 0.417 0.420 0.0027 0.430

1 SEM = standard error of the mean.a,b Means within a row without a common superscript letter differ (P



on overall growth performance and carcass composition, the cause of the variation in weaning weight must first be determined. Two major factors can create variation in weaning weight and the resulting impact on growth performance is very different. The first is variation in pig potential for growth. This can often times be attributed to the pigs birth weight, as birth weight effects on growth rate are evident at weaning (Peterson, 2008; Table 7). The subsequent impact on overall growth performance and carcass composition due to differences in weaning weight caused by differences in birth weight are similar to that described in the previous section. The second reason for weaning weight variation is environmental impact on pre-weaning growth rate, such as access to nutrients. Reduction in weaning weight due to lower nutrient consumption during lactation can be compensated for after weaning if the pig is placed on proper nutrition that meets the pigs nutrient requirements for growth. Wattanakul et al. (2007) conducted a study wherein weaning weights of entire litters were reduced by limiting access to the sow and thereby reducing suckling. The authors reported that pigs with lower weaning weights due to reduced suckling actually grew faster, consumed more feed, and had greater Gain:Feed ratios during the first 28 days post-weaning when compared to the non-limited pigs, and growth performance was similar for the remainder of the growth period. Similarly, Peterson (2008) reduced weaning weight of pigs with similar birth weights by rearing pigs in litters of either 6 or 12 pigs. The resulting difference in body weight at weaning was short lived, and the restricted pigs (reared in litters of 12) actually grew faster after weaning, resulting in no difference in overall growth performance (average daily gain, average daily feed intake, and gain to feed ratio) to a common harvest body weight (Table 7). These causes of weaning weight variation must be carefully considered when implementing practices that differentially manage pigs at weaning based on body weight, as the reason for the body weight variation may not be perfectly evident. It also must be noted that these points only consider the growth performance of the pigs. Heavier, more robust pigs at weaning should have a better chance of surviving the stresses that are encountered in commercial production systems immediately after weaning. Higher levels of mortality during the nursery period negatively affect whole herd feed conversion and profitability; thus robustness at weaning must always be a consideration for a production system.

Harvest weight

The harvest weight at which pigs are marketed in the industry has been consistently increasing. The reasons for this are that marketing pigs at heavier harvest weights can be a practical means of reducing costs in a production system by producing more pounds of pork per sow or maintaining the same level of production using fewer sows (Gil and Knowles, 2003). In addition, producers are able to take pigs to heavier weights by taking advantage of the increased lean deposition rates of modern genetic lines, and still producing pork with acceptable carcass and meat quality characteristics. However, if increasing the harvest weight of pigs is a strategy that is being considered, there are several important factors that need to be taken into account to achieve optimum production efficiency. From a live animal performance standpoint, increases in harvest weight of pigs above 100 kg has proven to have disadvantages mainly due to significant reductions in the efficiency of converting feed to lean meat (Richmond and Berg, 1971; Latorre et al., 2004). Other important factors that need to be considered are genetics, gender, in-barn management practices, feed and housing costs, desired carcass and meat quality characteristics, customer specifications, etc. For these reasons, the choice of the harvest weight needs to be



tailored specifically to each situation for a given production system. In general, growth rate is decreased with increasing harvest weight, and according to Weatherup et al. (1998) and Latorre et al. (2004) feed efficiency of finishing pigs is impaired by 0.01 kg for every 10-kg increase in harvest weights up to ~130 kg in mixed-gender groups (Table 8). From a biological standpoint, this happens because as pigs get heavier, the body composition changes, such that the proportion of the deposition of body fat relative to muscle increases. Because fat requires more energy to deposit than muscle, the quantity of feed per unit of gain increases with body weight (Figure 10). Although there is value to be captured by taking pigs to a heavier harvest weight, it is important that the right genetics, along with correct nutritional, management and marketing strategies are considered to maintain profitability for a production system.

Table 8. Effect of harvest weight on the growth performance of market weight pigs (Latorre et al., 2004).

Item Harvest weight (kg) SEM1 P-value

116 124 133

Start weight (kg) 74.9 74.7 74.8 0.43 0.94End weight (kg) 116.2c 124.4b 133.5a 1.30 0.001Average daily gain (g) 843a 788b 769b 18.5 0.05Average daily feed intake (kg) 2.69 2.56 2.68 0.056 0.23Gain:Feed 0.313a 0.309a 0.287b 0.003 0.001

1 SEM = standard error of the mean.a,b,c Means within a row without a common superscript letter differ (P



Pig removal strategies at marketing

When the pigs in the barn are getting close to harvest weight, pig producers have the challenging task of consistently selecting and shipping pigs at an ideal body weight for economic optimum. However, due to the large amount of body weight variation in a population of pigs at marketing, it is often advocated to remove pigs at the time of market over time, selecting the heaviest animals first, thereby allowing additional time and resources (floor and feeder space) for lighter pigs to reach an acceptable market weight (DeDecker, 2006). Several market strategies have been investigated with positive results in growth rate, largely caused by an increase in feed intake (DeDecker et al., 2005; Bates and Newcomb, 1997); however, there have been instances in which feed efficiency has also been improved which is a result of increased feed intake and improved feed utilization by the remaining pigs in the pen (Table 9). An additional benefit when using the right marketing strategy is the potential to reduce the total body weight variation of pigs marketed compared to pens remaining intact, thus allowing the producer to reduce the sort loss by shipping fewer pigs outside of the customers marketing grid. The best marketing strategy will be that which maximizes economic returns, but it is important to note that it will be specific to each production system situation. The point to keep in mind is that there is value in selecting the right pig at the right time during marketing as it relates to herd feed efficiency.

Table 9. Effect of removal strategy at slaughter on body weight and growth performance of pigs reared within a wean-to-finish system (DeDecker, 2002).

Item Removal treatment1 SEM2 P-value

0% 25% 50% 50% - space

Weight (kg)Before removal 113.0 113.7 113.3 113.7 0.57 0.769Start of test 113.0a 110.5b 105.8c 106.8c 0.65 0.001End of test 126.0a 126.5a 122.2b 121.5b 0.74 0.001

Within-pen CV (%)Before removal 9.31 9.47 9.60 9.45 0.37 0.959Start of test 9.31a 8.60a 6.85b 7.86ab 0.48 0.016End of test 9.43a 8.35ab 6.84b 8.05ab 0.54 0.032

Overall performanceAverage daily gain (g) 659c 829a 834a 754b 25.5 0.001Average daily feed intake (g) 2,795b 3,133a 3,036a 2,855b 51.0 0.001Gain:Feed 0.24b 0.26a 0.28a 0.26a 0.006 0.001

1 Removal treatment = 0% = 52 pigs/pen, 0 removed, 0.65 m2 floor space and 4.0 cm feeder space/pig; 25% = 25% removal, 39 pigs/pen, 13 removed, 0.87 m2 floor space and 5.4 cm feeder space/pig; 50% = 50% removal, 26 pigs/pen, 26 removed, 1.30 m2 floor space and 8.0 cm feeder space/pig; 50%-space = 50% removal and reduced space to that of Control.2 SEM = standard error of the mean.a,b,c Means within a row without a common superscript letter differ (P



Floor and feeder space impacts on feed efficiency

Pen resource allocation is an important consideration for modern pork production systems. Next to feed, housing is the second largest cost center for most modern, integrated swine production systems and therefore optimizing floor and feeder stocking rates is a critical component of profitability.

The optimum stocking rate for a facility should maximize throughput without compromising feed efficiency or increasing morbidity and mortality. Determining the optimum stocking rate requires a dynamic evaluation of the biological impact floor space allocation has on the pig. Floor space requirements must also be evaluated throughout the pigs life because the requirement changes as the pig grows.

Floor space requirements during the traditional nursery period (weaning to approximately eight to 10 weeks post-weaning) are much lower than those during the finishing phase. Restricted floor space during the nursery period has been reported to reduce growth rate; however, after the restriction is removed (when pigs are moved to a finisher or removed from an over-stocked wean to finish facility) the pigs will generally exhibit compensatory growth resulting in no impact on overall growth rate or feed efficiency (Wolter et al., 2003a).

Multiple research studies have reported a reduction in average daily gain with decreasing floor space allowances during the weaning to finish (Wolter et al., 2003b; Table 10) and finishing production periods (Kornegay and Notter, 1984; Gonyou et al., 2006; Shull, 2010). Many of these studies have reported this reduction in growth rate to be a result of lower daily feed intake and some researchers have reported a reduction in feed efficiency (NCR-89, 1993; Hyun et al., 1998). Another interesting finding in multiple research studies is a reduction in back fat associated with lower floor spaces (Ward et al., 1997; Brumm et al., 2001; Matthews et al., 2001). When environmental factors restrict the growth rate of pigs, the result is increased time required to reach

Table 10. Effects of floor space on wean-to-market performance (Wolter et al., 2003b).

Item Floor space1,2 SEM3 P-value

High Low

Start weight (kg) 5.5 5.5 0.01 NSEnd weight (kg) 119.3 118.2 0.34 0.06Average daily gain (g) 671 662 2.4 0.01Average daily feed intake (g) 1,737 1,699 9.6 0.01Gain:Feed 0.386 0.390 0.001 0.06

1 Floor space = high (0.63 m2) and low (0.31 ft2).2 Treatment duration = 12 or 14 week postweaning of floor space restriction.3 SEM = standard error of the mean.



a certain body weight accompanied by an increase in the overall requirement for maintenance energy. Therefore, it could be concluded that lowering the floor space provided to a pig and thus reducing its average daily gain would have an adverse affect on the pigs feed efficiency by increasing the total maintenance energy required compared to an unrestricted pig. However, this is not the case in many studies, and is likely due to the fact that pigs housed at lower floor spaces often have leaner carcasses. This reduction in efficiency due to slower growth rates at lower floor spaces is likely offset by the increase in efficiency associated with proportionally more lean tissue accretion in these slower growing pigs. This is obviously a fine balance and should be carefully evaluated within genotypes, nutrition programs, and housing systems in order to determine optimum stocking rates.

Lowering the amount of feeder space provided to pigs has been shown to have a similar effect as lowering floor space. Generally, increasing the number of pigs per feeder space will reduce feed intake and reduce average daily gain (Wolter et al., 2002b; Peterson et al., 2008; Table 11). Similar to floor space reduction, feeder space reduction has also been shown to reduce back fat (Peterson et al., 2008). Many different types of feeders exist in the industry and each one will have a different optimum stocking rate. If a feeder is designed with the proper dimensions to facilitate the natural feed intake behaviors of the pig, increasing the stocking rate on the feeder should not have a negative impact on feed efficiency until average daily gain has been reduced to the point that the overall maintenance energy requirement increase offsets the decrease in body fat. Increased competition at the feeder should also be considered, especially with feeder designs that may not be as ergonomically suited to the pig, as it could increase the amount of feed wastage when pigs are competing for the same feeder hole. In general, feeder space is a relatively inexpensive addition and can have a significant return on investment if it allows an increase in throughput within a facility.

Table 11. Effects of feeder trough space on nursery growth performance (Wolter et al., 2002b).

Item Feeder trough space1 SEM2 P-value

Unrestricted Restricted

Start weight (kg) 5.4 5.4 0.01 NSEnd weight (kg) 31.7 30.9 0.22



Out of feed events

Feed outages, or out-of-feed events, are a concerning problem in pig production systems. There are a number of reasons for out-of-feed events at the farm, either caused by the producer or by malfunctions in the equipment itself. In some instances, problems at the feed manufacturing facility can also disrupt timely feed delivery to the farm. This can lead to potential problems, some of which are documented in the literature: decreased growth rates, increased incidence of gastric ulcers, ileitis, and hemorrhagic bowel syndrome, etc. (Brumm et al., 2005). In addition, the production efficiency of the feed mill can be reduced as the number of feed emergency orders is increased, disrupting planned mill production. Research carried out in this area, although limited, shows that growth rate can be negatively impacted as a result of simulated repeated out-of-feed events (20 h in duration) especially in the earlier phases of the growth period, whereas pigs in the finisher phase are less affected. However, in the published research, feed efficiency of grow-finish pigs does not seem to be impacted in spite of repeated out-of-feed events (20 h in duration with a weekly, or up to three times per two week period frequency) if pigs are given access to feed and enough time to recover after a feed outage (Linneen et al., 2007; Brumm et al., 2008; Table 12 and 13). It should be borne in mind that in the research reported herein, each of the 20 hours feed outages was conducted from 12:00 to 08:00; this does not coincide with

Table 12. Frequent out-of-feed events on the growth performance of growing-finishing pigs weekly (Brumm et al., 2008).

Item Out of feed events SEM1 P-value

Never Weekly

Body weight (kg)Day 0 24.1 23.3 0.3 0.07Day 53 70.4 65.9 0.7 0.001Day 109 118.8 114.1 1 0.007

Average daily gain (kg)Day 0 to 52 0.873 0.805 10



the period of highest feeding activity generally observed in pigs in commercial practice and interpretation of this data must be done cautiously. The limited data in this area warrant further research under commercial conditions to fully understand the effect of out-of-feed events on the growth performance of grow-finish pigs.

Conclusion

With todays high feed cost environment, there will continue to be a lot of emphasis placed on feed efficiency. Thus, it is important that we measure feed conversion correctly. Due to the fact that most pigs are sold on a carcass basis, there is a strong argument to express feed efficiency on a carcass instead of a live basis. This becomes increasingly more important given the increased usage of low energy-high fiber diets. Producers should consider adjusting feed conversion data for factors such as body weight, energy level, and feed processing to improve system level interpretation and analysis. Alternatively, one might consider utilizing caloric efficiency to measure feed efficiency. When measuring feed conversion in the sow herd one needs to include the impact of sow productivity. As producers continue to look for ways to manage high feed costs, a significant economic opportunity exists to narrow the gap between actual performance

Table 13. Frequent out-of-feed events on the growth performance of growing-finishing pigs 1 to 3 times biweekly (Brumm et al., 2008).

Item Out of feed events SEM1 P-value

0 1 2 3 Treatment Linear

BW (kg)Day 0 17.8 18.1 18.6 17.8 0.4 0.38 0.76Day 56 64.7 64.3 63.6 59.9 1.2 0.05 0.01Day 112 117 117.6 117.5 113.8 1.2 0.13 0.10

Average daily gain (kg)Day 0 to 55 838 826 803 753 16 0.02 0.003Day 56 to 112 934 953 962 963 14 0.46 0.14Day 0 to 112 887 888 883 857 8 0.08 0.03

Average daily feed intake (kg)Day 0 to 55 1.87 1.85 1.81 1.68 0.045 0.04 0.01Day 56 to 112 3.19 3.12 3.21 3.16 0.049 0.6 0.97Day 0 to 112 2.53 2.49 2.51 2.42 0.04 0.3 0.11

Gain:FeedDay 0 to 55 0.449 0.447 0.445 0.449 0.005 0.91 0.94Day 56 to 112 0.291 0.302 0.297 0.302 0.004 0.18 0.11Day 0 to 112 0.35 0.358 0.353 0.355 0.003 0.41 0.52

1 SEM = standard error of the mean.



and genetic potential by focusing on the impact of various herd management factors such as, sow replacement rate, mortality, birth weight, weaning weight, floor space allowance, marketing strategy, and out-of-feed events that could be impacting feed efficiency.

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41

2. Feeding and barn management strategies that maximize feed

efficiency

M.D. Tokach, R.D. Goodband, J.M. DeRouchey, S.S. Dritz and J.L. NelssenDepartment of Animal Sciences and Industry, Kansas State University, 246 Weber Hall, Manhattan, KS 66506-8028, USA; [email protected]

Abstract

The stockperson is responsible for the daily care and welfare of pigs in the barn. Through their actions, they also can influence overall feed efficiency. Prior to loading pigs, thoroughly cleaning and operating the facility in an all-in, all-out manner has shown to improve pig performance and feed efficiency. Removing feed from previous groups of pigs and repairing feeding and ventilation equipment influence closeout feed efficiency. When loading the barn, pigs should not be sorted into narrow weight categories. With weanling pigs, mat feeding can help increase feed consumption and reduce mortality immediately after weaning; however, prolonged mat feeding will result in feed wastage. After loading, daily chores that influence overall feed efficiency include individual pig treatment and timely euthanasia, ensuring water and feed availability, feeding the appropriate diet, managing the air quality and environmental temperature, properly adjusting feeders, and handling pigs in a positive manner. Removing a portion of the pigs from all pens during initial marketing events can result in feed savings while maximizing weight produced from the facility. Withdrawing feed prior to market also can result in feed savings. Proper handling during loading and transport to the processor to minimize mortality also can influence closeout feed efficiency. The stockperson can play a large role in improving overall feed efficiency by how they manage their day-to-day activities in the barn. This chapter will focus on these activities and their impact on feed efficiency.

Introduction

As discussed in other chapters, genotype, gender, market weight and dietary factors, such as energy and amino acid levels, diet form (e.g. pelleting or particle size), and additives (e.g. ractopamine) are the major drivers of differences in feed efficiency among production systems. However, many factors within production systems also lead to differences in feed efficiency.

Even after standardizing genetics, facilities, feeders, diets, weights and as many other variables as possible, feed efficiency and growth rate can remain highly variable within an individual production system. Once this variation is measured and noted, the question is how to reduce it.

For discussion of the actions that people in the barn can do on a day-to-day basis to influence feed efficiency, we will separate barn management into four phases of a barn turn that people in the barn can do: (1) prior to entry; (2) while loading the barn; (3) through daily chores, and (4) while unloading the barn at marketing time. Each of these four phases of barn management provides unique opportunities to influence feed efficiency. There are also some activities that are

J.F. Patience (ed.), Feed efficiency in swine, DOI 10.3920/978-90-8686-756-1_2, Wageningen Academic Publishers 2012


M.D. Tokach, R.D. Goodband, J.M. DeRouchey, S.S. Dritz and J.L. Nelssen

emphasized by some producers that are not as important as they believe. These action items that should be moved down the priority list or eliminated will also be discussed.

Prior to entry

The majority of modern swine production systems around the world manage their growing facilities on an all-in, all-out basis where all of the pigs are removed before another group of pigs enter the facility. This management style has greatly improved performance by decreasing horizontal transfer of disease from one group of pigs to the next (Cargill and Banhazi, 1998). All-in, all-out production also provides a unique opportunity for the barn manager to start anew with each group. The main areas for focus prior to entry are thoroughly cleaning the barn, maintenance and repair of equipment, and ensuring feed bins are empty before delivering new feed.

Thoroughly clean the barn

The primary objective of barn cleaning practices is to lower the dose of infectious pathogens that can be transmitted from one group of pigs to the next. Environmental contamination is an important contributor to bacterial and viral infections. For example, Davies et al. (1999) found that 27% (7/26) of samples obtained from a fully slatted finishing floor just prior to placement of pigs were found to be positive for salmonella. Cargill and Banhazi (1998) found that cleaning barns between groups of pigs was the most important component of all-in, all-out production. It led to improved pig performance and a greater reduction in respirable dust particles, viable bacteria counts, and gram positive bacteria counts than gained by adopting all-in, all-out production without cleaning barns (Table 1).

It has been well documented that animal performance is increased in clean vs. dirty environments (Renaudeau, 2009). Pigs reared in a dirty environment had a 10% reduction in average daily gain (ADG) (0.78 vs. 0.87 kg) and 18% reduction in feed intake (1.86 vs. 2.28 kg) as compared with

Table 1. Influence of all-in, all-out management and cleaning between batches of pigs on growth performance and air quality measurements (adapted from Cargill and Banhazi, 1998).

Item1 All-in, all-out; cleaned

All-in, all-out; not cleaned

Continuous flow

Average daily gain (g) 658a 619b 610b

Airborne dust (mg/m3) 1.80 2.31 2.51Respirable particles (mg/m3) 0.201a 0.265b 0.29b

Viable bacteria (CFU 103/m3) 132a 177b 201b

Gram positive bacteria (CFU 103/m3) 82a 109b 122b

1 CFU = colony forming units.a,b Groups without a common superscript letter differ at P


2. Feeding and barn management strategies that maximize feed efficiency

pigs reared in a clean environment. The influence of sanitation on pig performance appears to impact feed intake and thus growth rate to a greater extent than feed efficiency.

Cleanliness is probably responsible for a large percentage of the growth performance benefits from all-in, all-out production (Amass et al., 2001). Fortunately, most swine pathogens only survive for a brief amount of time outside the host in the absence of organic materials or moisture. Under experimental conditions, up to 99% of the bacteria can be removed by cleaning alone. Removal of visible organic matter removes 90% of bacteria from the environment. Another 6 to 7% of bacteria are killed by disinfectants with a final 1 to 2% killed by fumigation (Morgan-Jones, 1987). Letting the barn dry between washing and loading with pigs also plays a role in pathogen load. When we cannot let the facility dry, viruses have the opportunity to survive for extended periods of time. For example, PRRS can survive in water for up to 11 days; however, when dried it dies quickly (Pirtle and Beran, 1996).

When washing, one of the frequent errors producers make is not adequately cleaning feeders and waterers or not removing disinfectant and water from feeders or waterers. Because many feeders and waterers are not easily removed for cleaning, other methods must be used to remove water and dry them. Some producers use leaf blowers to remove the water from feeders and waterers that are not easily moved for cleaning.

Basic hygiene practices to decrease pathogen transmission from group to group include: (1) Building materials that are easy to clean. Rough surfaces such as concrete are more difficult to clean than smooth surfaces such as wire and plastic. Smooth nonporous surfaces will provide easier removal of fecal matter and faster drying. (2) Thorough cleaning and removal of organic matter such as feces and feed. In general, organisms are protected against disinfection agents by organic materials such as pus, serum, or feces. (3) Proper use of disinfectants including correct dilution and application. Diluting the disinfectant below its proper dosage or applying disinfectant to manure covered floors render it ineffective. (4) Lastly, proper downtime and drying of rooms is vital to minimizing pathogen load.

A survey of hygiene practices on 129 French farms indicated several practices associated with decreased residual contamination in nurseries (Madec et al., 1999). The practices included dampening of the rooms immediately after moving the pigs out of the room. The researchers hypothesized that dampening prevented dying of the fecal matter and increased the ease and thoroughness of cleaning. Using a detergent was also recommended and associated with decreased residual contamination. However, in another study evaluating the impact of using a detergent, the researchers were unable to detect any impact on residual contamination after thorough washing (Kihlstrom et al., 2001). This indicates that using a detergent may improve the ease of cleaning; however, if cleaning procedures are thorough, detergents may not impact the final amount of residual contamination.

Several other studies indicated that thorough cleaning and removal of organic matter resulted in less residual contamination (Amass et al., 2001; Kihlstrom et al., 2001). Additionally, greater distances between the surface of the slurry and the floor were associated with less residual contamination. The authors attributed this risk factor to splash back and recontamination during



the cleaning process. Finally, factors associated with disinfectant usage such as proper dilution and application were important. Commonly available disinfectants vary widely in their ability to neutralize viruses such as porcine circovirus type 2 (PCV2; Figure 1). Royer et al. (2001) evaluated 11 commonly used disinfectants in swine farms and research laboratories. These included several disinfectant classes (products) tested: ethanol (alcohol), iodine (Weldol), phenol (1-Stroke, Tek-Trol), quaternary ammonium (Roccal D Plus, Fulsan), oxidizing agent (Clorox, VirkonS), alkali (NaOH), and chlorhexidine (Nolvasan). The mean titer after disinfection ranged from 5.2 for the chlorhexidine to 1.6 for the oxidizing agent VirkonS (log 10 scale). This compares to the control titer without disinfection of 6.0. The log 10 scale indicates that the reduction from 6 to 5 results in a 90% reduction, from 6 to 4 a 99% reduction, from 6 to 3 a 99.9% reduction and from 6 to 1 a 99.99% reduction of the virus. There are two important points to remember from this study:1. PCV2 is a small enveloped virus similar to Parvovirus and thus, difficult to neutralize with

disinfectants.2. This study was conducted under controlled laboratory conditions and designed for maximum

disinfectant activity. Disinfectant activity may be less effective in the field setting.

Although our knowledge on proper cleaning and disinfecting procedures for swine facilities is not complete, considerable research has improved our knowledge base in the past 10 years. In addition to the PCV2 disinfectant evaluation, this includes evaluation of farrowing house cleaning protocols, boot bath cleaning disinfectants and procedures, and methods to rapidly evaluate surface contamination in swine facilities (Amass et al., 2001; Kelly et al., 2001; Kihlstrom et al., 2001; Amass, 2004; Martin et al., 2008).

Maintenance and repair of equipment

The best time to conduct maintenance is when the barn is empty. Most good producers have a mental list of items that must be done between groups, but it is helpful to keep a log of items that need to be fixed, replaced, or serviced when the barns are empty. These could include items such as greasing bearings on augers or repairing waterers, gates, feeders, inlets, curtains, or insulation.

Figure 1. Reduction in infectivity of PCV2 after a 10 min disinfectant exposure (Royer et al., 2001).

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2. Feeding and barn management strategies that maximize feed efficiency

From a feed efficiency perspective, maintenance of feed handling is of utmost importance. This would include fixing any leaking feed bins, broken feed lines, feeder adjustment rods or other feeder parts (Figure 2). In order to understand the importance of proper maintenance on feed equipment, it may be helpful to consider the amount of feed passing through a single feeder or barn on an annual basis. For example, a 1,200 head barn with 48 pens (28 pigs per pen) will have 24 fenceline feeders. If feed efficiency is 2.8 and the pigs gain 100 kg during the finishing period, each pig would consume 280 kg of feed. Thus, 15,680 kg of feed would pass through each feeder and a total of 376,320 kg of feed would be used in the barn during a single turn. If 2.8 groups of pigs are fed in the barn each year, the quantity of feed passing through a feeder and through the entire barn increases to 43,904 kg and 1,053,696 kg, respectively. Thus, each feeder handles almost 44 tonnes of feed and over 1,000 tonnes are used in the barn annually. If diet cost is $280 per metric ton, the value of feed used per feeder and barn would be greater than $12,000 and $295,000 annually. Repairing feed handling equipment to save a small portion of this expense pays big dividends.

Other equipment, such as watering, ventilation, heating, and cooling equipment, also should be checked and repaired as needed. If pigs are above or below their thermoneutral zone because of equipment malfunctions, feed efficiency and growth rate will be negatively impacted.

Before pigs are loaded into the barn, equipment also should be checked to ensure the settings are correct for starting pigs. Ventilation controllers, temperature probes, fans, and curtains should be checked to make sure they are operational and that temperatures and ventilation are set for the

Figure 2. Feed spills.



appropriate number and weight of pigs. Before the

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