Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-24T05:37:10.612Z Has data issue: false hasContentIssue false
  • English
  • Français

Opportunities to improve nutrient efficiency in pigs and poultry through breeding

Published online by Cambridge University Press:  04 January 2011

I. Kyriazakis
I. Kyriazakis*
Affiliation:
Veterinary Faculty, University of Thessaly, PO Box 199, 43100 Karditsa, Greece School of Agriculture, Food and Rural Development, Newcastle University, Newcastle-upon-Tyne, NE1 7RU, England
*
†E-mail: [email protected]
Get access

Abstract

Efficiency of food and nutrient (including energy) use are considered the key factors in the economic and environmental performance of livestock systems. The aim of this paper is to consider the basis of genetic variation in the components that constitute dietary nutrient efficiency; and to conclude whether there would be benefit, in any relevant terms, in including these components in breeding programmes that aim to improve nutrient efficiency within pig and poultry systems of production. The components considered are (i) external, pre-ingestion losses, such as food spillage and its relation to feeding behaviour traits, (ii) digestive efficiency, (iii) maintenance requirements, (iv) net efficiency of energy and nutrient utilisation and (v) partitioning of scarce resources within productive and between productive and fitness functions. It is concluded that opportunities to exploit genetic variation exist mainly in the potential to improve the digestive efficiency of pigs and to reduce the maintenance requirements for resources mainly in hens, but also potentially in pigs. Current evidence suggests that there are very weak genetic and phenotypic correlations between components of feeding behaviour and productive traits, and little genetic variation in the net efficiency of nutrient utilisation among poultry and pig genotypes. The implication of the latter is that there would be little exploitable genetic variation in the partitioning of scarce nutrients between productive functions. Currently, there is a lack of understanding of the genetic basis of the partitioning of scarce nutrients between productive and fitness functions, and how this may impact upon the efficiency of nutrient use in pig and poultry systems. This is an area of research to which further effort might usefully be devoted.

Keywords

breedingnutrient efficiencypartitioningpigspoultry
Type
Full Paper
Information
animal , Volume 5 , Issue 6 , June 2011 , pp. 821 - 832
Copyright
Copyright © The Animal Consortium 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Barnett, JL, Hemsworth, PH, Cronin, GM, Winfield, CG, McCallum, TH, Newman, EA 1988. The effects of genotype on physiological and behavioural responses related to the welfare of pregnant pigs. Applied Animal Behavioural Science 20, 287–296.CrossRefGoogle Scholar
Bhargava, KK, Hanson, RP, Sunde, ML 1970a. Effects of methionine and valine on antibody production in chicks infected with Newcastle disease virus. Journal of Nutrition 100, 241–248.CrossRefGoogle ScholarPubMed
Bhargava, KK, Hanson, RP, Sunde, ML 1970b. Effects of threonine on growth and antibody production in chicks infected with Newcastle disease virus. Poultry Science 50, 710–713.CrossRefGoogle Scholar
Bishop, SC, Kyriazakis, I 2008. Selection for disease resistance: potential impacts on emissions. In Defra Project Report AC0204, A study of the scope for the application of research in animal genomics and breeding to reduce nitrogen and methane emissions from livestock based food chains. http://randd.defra.gov.uk/Document.aspx?Ducument=AC0204_7639_FRP.docGoogle Scholar
Black, JL, Davis, GT, Bray, HJ, Giles, LR, Chapple, RP 1986. Simulation of energy and amino acid utilisation in the pig. Research and Development in Agriculture 3, 121–145.Google Scholar
Bottje, WG, Carstens, GE 2009. Association of mitochondrial function and feed efficiency in poultry and livestock species. Journal of Animal Science 87, E48–E63.CrossRefGoogle ScholarPubMed
Buyse, J, Michels, H, Vloeberghs, J, Saevels, P, Aerts, JM, Ducro, B, Berckmans, D, Decuypere, E 1998. Energy and protein metabolism between 3 and 6 weeks of age of male broiler chickens selected for growth rate or for improved food efficiency. British Poultry Science 39, 264–272.CrossRefGoogle ScholarPubMed
Cameron, ND, Garth, PB, Penman, JC, Fiskin, A 2003. Sensitivity to dietary lysine: energy content in pigs divergently selected for components of efficient lean growth rate. Animal Science 76, 175–189.CrossRefGoogle Scholar
Campbell, RG, Dunkin, AC 1983. The effects of energy intake and dietary protein on nitrogen retention, growth performance, body composition and some aspects of energy metabolism of baby pigs. British Journal of Nutrition 49, 221–230.CrossRefGoogle ScholarPubMed
Campo, JL, Gil, MG, Torres, O, Davila, SG 2001. Association between plumage condition and fear and stress levels in five breeds of chickens. Poultry Science 80, 549–552.CrossRefGoogle ScholarPubMed
Carré, B, Mignon-Grasteau, S, Juin, H 2008. Breeding for feed efficiency and adaptation to feed in poultry. Worlds Poultry Science Journal 64, 377–390.CrossRefGoogle Scholar
Colditz, IG 2002. Effects of the immune system n metabolism: implications for production and disease resistance in livestock. Livestock Production Science 75, 257–268.CrossRefGoogle Scholar
Coop, RL, Kyriazakis, I 1999. Nutrition–parasite interaction. Veterinary Parasitology 84, 187–204.CrossRefGoogle ScholarPubMed
Datta, FIJ, Nolan, JV, Rowe, JB, Gray, GD 1998. Protein supplementation imporves the performance of parasitized sheep fed straw-based diet. International Journal for Parasitology 28, 1269–1278.CrossRefGoogle ScholarPubMed
de Greef, KH, Verstegen, MWA 1993. Partitioning of body protein and lipid deposition in the body of growing pigs. Livestock Production Science 35, 317–325.CrossRefGoogle Scholar
de Greef, KH, Kemp, B, Verstegen, MWA 1992. Performance and body composition of fattening pigs of two strains during protein deficiency and subsequent realimentation. Livestock Production Science 30, 141–153.CrossRefGoogle Scholar
Doeschl-Wilson, AB, Brindle, W, Emmans, GC, Kyriazakis, I 2009a. Unravelling the relationship between animal growth and immune response during micro-parasitic infections. PLoS ONE 4, e7508. http://dx.plos.org/10.1371/journal.pone.0007508CrossRefGoogle ScholarPubMed
Doeschl-Wilson, AB, Kyriazakis, I, Vincent, A, Rothchild, MF, Thacker, E, Galina-Pantoja, L 2009b. Clinical and pathological responses of pigs from two genetically diverse commercial lines to porcine reproductive and respiratory syndrome virus infection. Journal of Animal Science 87, 1638–1647.CrossRefGoogle ScholarPubMed
Dunnington, EA, Siegel, PB 1995. Enzyme activity and organ development in newly hatched chicks selected for high or low eight-week body weight. Poultry Science 74, 761–770.CrossRefGoogle ScholarPubMed
Emmans, GC 1994. Effective energy – a concept of energy utilization applied across species. British Journal of Nutrition 71, 801–821.CrossRefGoogle ScholarPubMed
Emmans, GC 1997. A method to predict the food intake of domestic animals from birth to maturity as a function of time. Journal of Theoretical Biology 186, 189–199.CrossRefGoogle Scholar
Emmans, GC, Kyriazakis, I 2000. Issues arising from genetic selection for growth and body composition characteristics in poultry and pigs. In The challenge of genetic change in animal production (ed. WG Hill, SC Bishop, B McGuirk, JC McKay, G Simm and AJ Webb), pp. 39–53. Occasional Publication of the British Society of Animal Science No. 27, Edinburgh, UK.CrossRefGoogle Scholar
Fevrier, C, Bourdon, D, Aumaitre, A 1992. Effects of level of dietary fiber from wheat bran on digestibility of nutrients, digestive enzymes and performance in the European Large White and Chinese Mei Shan pig. Journal of Animal Physiology and Animal Nutrition 68, 60–72.CrossRefGoogle Scholar
Food and Agriculture Organisation (FAO) 2009. The state of food and agriculture. Food and Agriculture Organisation of the United Nations, Rome.Google Scholar
Fuller, MF, Franklin, MF, McWilliam, R, Pennie, K 1995. The responses of growing pigs, of different sex and genotype, to dietary energy and protein. Animal Science 60, 291–298.CrossRefGoogle Scholar
Geraert, PA, MacCleod, MG, Leclercq, YDB 1988. Energy metabolism in genetically fat and lean chickens: diet- and cold-induced thermogenesis. Journal of Nutrition 118, 1232–1239.CrossRefGoogle ScholarPubMed
Geraert, PA, MacLeod, MG, Larbier, M, Leclercq, B 1990. Nitrogen metabolism in genetically fat and lean chickens. Poultry Science 69, 1911–1921.CrossRefGoogle ScholarPubMed
Gous, RM 2007. Predicting nutrient responses in poultry: future challenges. Animal 1, 57–65.CrossRefGoogle ScholarPubMed
Henken, AM, Vanderhel, W, Brandsma, HA, Verstegen, MWA 1991. Differences in energy-metabolism and protein retention of limit-fed growing pigs of several breeds. Journal of Animal Science 69, 1443–1453.CrossRefGoogle ScholarPubMed
Houdijk, JGM, Jackson, F, Kyriazakis, I 2009. Nutritional sensitivity of resistance to Trichostorngylus colubriformis in lactating ewes. Veterinary Parasitology 60, 258–266.CrossRefGoogle Scholar
Howie, J 2010. The use of genetic variation in sort-tem feeding behaviour in broiler breeding programmes. PhD thesis, University of Edinburgh.Google Scholar
Howie, J, Tolkamp, BJ, Avandano, S, Kyriazakis, I 2009. The structure of feeding behaviour in commercial broiler lines selected for different growth rates. Poultry Science 88, 1143–1150.CrossRefGoogle ScholarPubMed
Huff, GR, Huff, WE, Balog, JN, Rath, NC, Anthony, NB, Nestor, KE 2005. Stress response differences and disease susceptibility reflected by heterophil to lymphocyte ratio in turkeys selected for increased body weight. Poultry Science 84, 709–717.CrossRefGoogle ScholarPubMed
Jensen, MB, Kyriazakis, I, Lawrence, AB 1993. The activity and straw directed behaviour of pigs offered foods with different crude protein content. Applied Animal Behavioural Science 37, 211–221.CrossRefGoogle Scholar
Jorgensen, H, Sorensen, P, Eggum, BO 1990. Protein and energy-metabolism in broiler-chickens selected for either body weight gain or feed efficiency. British Poultry Science 31, 517–524.CrossRefGoogle ScholarPubMed
Katle, J 1991. Selection for efficiency of food utilization in laying hens – causal factors for variation in residual feed consumption. Poultry Science 32, 955–969.CrossRefGoogle Scholar
Kemp, B, Den Hartog, LA, Klok, JJ, Zandstra, T 1991. The digestibility of nutrients, energy and nitrogen in the Meishan and Dutch Landrace pig. Journal of Animal Physiology and Animal Nutrition 65, 263–266.CrossRefGoogle Scholar
Kidane, A, Houdijk, JGM, Athanasiadou, S, Tolkamp, BJ, Kyriazakis, I 2010. Nutritional sensitivity of periparturient resistance to nematode parasites in two breeds of sheep with different nutrient demands. British Journal of Nutrition 104, 1477–1486.CrossRefGoogle ScholarPubMed
Klasing, KC, Laurin, DE, Peng, RK, Fry, M 1987. Immunologically mediated growth depression in chicks: influence of feed intake, corticosterone and interleukin-1. Journal of Nutrition 117, 1629–1637.CrossRefGoogle ScholarPubMed
Knap, PW 2009. Allocation of resources to maintenance. In Resource allocation theory applied to farm animal production (ed. WM Rauw), pp. 110–129. CAB International, Wallingford, Oxon.Google Scholar
Knap, PW, Rauw, WM 2009. Selection for high production in pigs. In Resource Allocation theory applied to farm animal production (ed. WM Rauw), pp. 210–229. CAB International, Wallingford, Oxon.Google Scholar
Kyriazakis, I, Emmans, GC 1992a. The effects of varying protein and energy intakes on the growth and body composition of pigs. 1. The effects of energy intake at constant, high protein intake. British Journal of Nutrition 68, 603–613.CrossRefGoogle ScholarPubMed
Kyriazakis, I, Emmans, GC 1992b. The effects of varying protein and energy intakes on the growth and body composition of pigs. 2. The effects of varying both energy and protein intake. British Journal of Nutrition 68, 615–625.CrossRefGoogle ScholarPubMed
Kyriazakis, I, Emmans, GC 1995. Do breeds of pig differ in the efficiency with which they use a limiting protein supply? British Journal of Nutrition 74, 183–195.CrossRefGoogle ScholarPubMed
Kyriazakis, I, Houdijk, JGM 2007. Food intake and performance of pigs during health, disease and recovery. In Paradigms in pig science (ed. J Wiseman, MA Varley, S McOrist and B Kemp), pp. 493–513. Nottingham University Press, Nottingham.Google Scholar
Kyriazakis, I, Whittemore, CT 2006. Whittemore's science and practice of pig production. Blackwell Publishing, Oxford.CrossRefGoogle Scholar
Kyriazakis, I, Dotas, D, Emmans, GC 1994. The effect of breed on the relationship between feed composition and the efficiency of protein-utilization in pigs. British Journal of Nutrition 71, 849–859.CrossRefGoogle ScholarPubMed
Labroue, F, Gueblez, R, Sellier, P 1997. Genetic parameters of feeding behaviour and performance traits in group-housed Large White and French Landrace growing pigs. Genetics Selection Evolution 29, 451–468.CrossRefGoogle Scholar
Labroue, F, Gueblez, R, Meuneir-Salaun, MC, Sellier, P 1999. Feed intake behaviour of group-housed Pietrain and Large White growing pigs. Annales de Zootechnie 48, 247–261.CrossRefGoogle Scholar
Laurin, DE, Touchburn, SP, Chavez, ER, Chan, CW 1985. Methods of measuring energy utilization in broilers: effect of genetic line and presence of supplemental dietary fat. Poultry Science 64, 969–978.CrossRefGoogle ScholarPubMed
Leclercq, B, Saadoun, A 1982. Selecting broilers for low or high abdominal fat: comparison of energy metabolism of the lean and fat lines. Poultry Science 61, 1799–1803.CrossRefGoogle Scholar
Lee, JE, Austic, RE, Naqi, SA, Golemboski, KA, Dietert, RR 2002. Dietary arginine intake alters avian leukocyte population distribution during infectious bronchitis challenge. Poultry Science 81, 793–798.CrossRefGoogle ScholarPubMed
Leenstra, FR, Pit, R 1987. Fat deposition in a broiler sire strain. 2. Comparisons among lines selected for less abdominal fat, lower feed conversion ratio and higher body weight after restricted and ad libitum feeding. Poultry Science 66, 193–202.CrossRefGoogle Scholar
Lepron, E, Bergeron, R, Robert, S, Faucitano, L, Bernier, JF, Pomar, C 2007. Relationship between residual energy intake and the behaviour of growing pigs from three genetic lines. Livestock Science 111, 104–113.CrossRefGoogle Scholar
Lopez, G, Leeson, S 2008. Review: energy partitioning in broiler chickens. Canadian Journal of Animal Science 88, 205–212.CrossRefGoogle Scholar
Ly, J, Ty, C, Samkol, P 2003. N balance studies in young Mong Cai and Large White pigs fed high fibre diets based on wheat bran. Livestock Research for Rural Development 15. http://www.lrrd.org/lrrd15/1/ly151.htmGoogle Scholar
Luiting, P 1990. Genetic variation of energy partitioning in laying hens. Causes of variation in residual feed consumption. Worlds Poultry Science Journal 46, 133–152.CrossRefGoogle Scholar
Luiting, P, Urff, EM 1991. Optimization of a model to estimate residual feed consumption in the laying hen. Livestock Production Science 27, 321–338.CrossRefGoogle Scholar
Luiting, P, Schrama, JW, van der Hel, W, Urff, EM 1991. Metabolic differences between White Leghorns selected for high and low residual food consumption. British Poultry Science 32, 763–782.CrossRefGoogle ScholarPubMed
McKay, JC, Barton, NF, Kolhuis, ANM, McAdam, J 2000. The challenge of genetic challenge in the broiler chicken. In The challenge of genetic change in animal production (ed. WG Hill, SC Bishop, B McGuirk, JC McKay, G Simm and AJ Webb), pp. 1–7. Occasional Publication of the British Society of Animal Science No. 27, Edinburgh, UK.CrossRefGoogle Scholar
Magnusson, U, Bosse, J, Mallard, BA, Rosendal, S, Wilkie, BN 1997. Antibody response to Actinobacillus pleuropneumoniae antigens after vaccination of pigs bred for high and low immune response. Vaccine 15, 997–1000.CrossRefGoogle ScholarPubMed
Mignon-Grasteau, S, Muley, N, Bastianelli, D, Gomez, J, Peron, A, Sellier, N, Millet, N, Besnard, J, Hallouis, JM, Carre, B 2004. Heritability of digestibilities and divergent selection for digestion ability in growing chicks fed a wheat diet. Poultry Science 83, 867–869.CrossRefGoogle ScholarPubMed
Mitchell, MA, Smith, MW 1991. The effects of genetic selection for increased growth rate on mucosal and muscle weights in the different regions of the small intestine of the domestic chicken (Gallus domesticus). Comparative Biochemistry and Physiology 1/2, 251–258.CrossRefGoogle Scholar
Morales, J, Perez, JF, Baucells, MD, Mourot, J, Gasa, J 2002. Comparative digestibility and lipogenic activity in Landrace and Iberian finishing pigs fed ad libitum corn- and corn-sorghum-acorn-based diets. Livestock Production Science 77, 195–205.CrossRefGoogle Scholar
Morel, PCH, Lee, TS, Moughan, PJ 2006. Effect of feeding level, live weight and genotype on the apparent faecal digestibility of energy and organic matter in the growing pig. Animal Feed Science and Technology 126, 63–74.CrossRefGoogle Scholar
National Research Council 1994. The nutrient requirements of poultry, 9th edition. The National Academies Press, Washington, DC.Google Scholar
Noblet, J, Fortune, H, Dubois, S, Henry, Y 1989. Nouvelles bases d'estimation des teneurs en énergie digestible, metabolisable et nette des aliments pour le porc. INRA, Paris.Google Scholar
Noblet, J, Karege, C, Dubois, S, van Milgen, J 1999. Metabolic utilization of energy and maintenance requirements in growing pigs: effects of sex and genotype. Journal of Animal Science 77, 1208–1216.CrossRefGoogle ScholarPubMed
Péron, A, Gomez, J, Mignon-Grasteau, S, Sellier, N, Besnard, J, Derouet, M, Juin, H, Carre, B 2006. Effects of wheat quality on digestion differ between the D+ and D− chicken lines selected for divergent digestion capacity. Poultry Science 85, 462–469.CrossRefGoogle Scholar
Petry, DB, Holl, JW, Weber, JS, Doster, AR, Osorio, FA, Johnson, RK 2005. Biological responses responses to porcine respiratory and reproductive syndrome virus in pigs of two genetic populations. Journal of Animal Science 83, 1494–1502.CrossRefGoogle ScholarPubMed
Pishnamazi, A, Pourezza, J, Edriss, MA, Samie, AH 2005. Influence of broiler breeder and laying hen breed on the apparent metabolisable energy of selected feed ingredients. International Journal of Poultry Science 4, 163–166.Google Scholar
Pym, RAE 1985. Direct and correlated responses to selection for improved feed efficiency. In Poultry breeding and genetics (ed. WG Hill, JM Manson and D Hewitt), pp. 97–112. British Poultry Science, Edinburgh, UK.Google Scholar
Pym, RAE, Leclercq, B, Tomas, FM, Tesseraud, S 2004. Protein utilisation and turnover in lines of chickens selected for different aspects of body composition. British Poultry Science 45, 775–786.CrossRefGoogle ScholarPubMed
Pym, RAE, Nicholls, PJ, Thomson, E, Choice, A, Farrell, DJ 1984. Energy and nitrogen metabolism of broilers selected over ten generations for increased growth rate, food consumption and conversion of food to gain. British Poultry Science 25, 529–539.CrossRefGoogle ScholarPubMed
Quiniou, N, Dourmad, J-Y, Nobelt, J 1996. Effect of energy intake on the performance of different types of pig from 45–100 kg body weight. Animal Science 63, 277–288.CrossRefGoogle Scholar
Rauw, WM, Kanis, E, Noordhuizen-Stassen, EN, Grommers, FJ 1998. Undesirable side effects of selection for high production efficiency in farm animals: a review. Livestock Production Science 56, 15–33.CrossRefGoogle Scholar
Richardson, EC 2003. Biological basis for variation in residual feed intake in beef cattle. PhD thesis, University of New England, Armidale, Australia.Google Scholar
Sandberg, FS, Emmans, GC, Kyriazakis, I 2005a. Partitioning of limiting protein and energy in the growing pig. 1. Description of the problem, possible rules and their qualitative evaluation. British Journal of Nutrition 93, 205–212.CrossRefGoogle Scholar
Sandberg, FS, Emmans, GC, Kyriazakis, I 2005b. Partitioning of limiting protein and energy in the growing pig. 2. Testing quantitative rules against experimental data. British Journal of Nutrition 93, 213–224.CrossRefGoogle ScholarPubMed
Sandberg, FS, Emmans, GC, Kyriazakis, I 2007. The effects of pathogen challenges on the performance of naive and immune animals: the problem of prediction. Animal 1, 67–86.CrossRefGoogle ScholarPubMed
Savon, L 2005. Tropical roughages and their effect on the digestive physiology of monogastric species. Cuban Journal of Agricultural Science 39, 463–474.Google Scholar
Schrama, JW, Schouten, JM, Swinkels, JWGM, Gentry, JL, Reiligh, GD, Parmentier, HK 1997. Effects of haemoglobin status on humorla immune response of weaning pigs difefreing in coping styles. Journal of Animal Science 75, 2588–2596.CrossRefGoogle Scholar
Skinner-Noble, DO, Jones, RB, Teeter, RG 2003. Components of feed efficiency in broiler breeding stock: is improved feed conversion associated with increased docility and lethargy in broilers. Poultry Science 82, 532–537.CrossRefGoogle ScholarPubMed
Spratt, RS, Leeson, S 1987. Determination of metabolizable energy of various diets using Leghorn, Dwarf and regular broiler breeder hens. Poultry Science 66, 314–317.CrossRefGoogle ScholarPubMed
Steinfeld, H, Gerber, P, Wassenaar, T, Castel, V, Rosales, M, de Haan, C 2006. Livestock's Long Shadow Food and Agriculture Organisation of the United Nations, Rome.Google Scholar
Susenbeth, A, Dickel, T, Diekenhorst, A, Hohler, D 1999. The effect of energy intake, genotype, and body weight on protein retention in pigs when dietary lysine is the first-limiting factor. Journal of Animal Science 77, 2985–2989.CrossRefGoogle ScholarPubMed
Svihus, B, Juvik, E, Hetland, H, Krogdahl, A 2004. Causes for improvement in nutritive value of broiler chicken diets with whole wheat instead of ground wheat. British Poultry Science 45, 55–60.CrossRefGoogle ScholarPubMed
Swennen, Q, Janssens, GPJ, Collin, A, Le Bihan-Duval, E, Verbeke, K, Decuypere, E, Buyse, J 2006. Diet-induced thermogenesis and glucose oxidation in broiler chickens: influence of genotype and diet composition. Poultry Science 85, 731–742.CrossRefGoogle ScholarPubMed
Swennen, Q, Verhulst, P-J, Collin, A, Bordas, A, Verbeke, K, Vansant, E, Decuypere, E, Buyse, J 2007. Further investigations on the role of diet-induced thermogenesis in the regulation of feed intake in chickens: comparisons of adult cockerels of lines selected for high or low residual feed inatke. Poultry Science 86, 1960–1971.CrossRefGoogle ScholarPubMed
Taylor St, CS 1965. A relationship between mature weight and time taken to mature in mammals. Animal Production 7, 203–220.Google Scholar
Thiessen, RB, Taylor St, CS 1986. Genetic variability among cattle breeds for beef production. Animal Production 32, 29–37.Google Scholar
ten Doeschate, RAHM, Scheele, CW, Schreurs, WAM, van der Klis, JD 1993. Digestibility studies in broiler-chickens – influence of genotype, age, sex and method of determination. British Poultry Science 34, 131–146.CrossRefGoogle Scholar
Van Eerden, E, Van Den Brand, H, Parmentier, HK, de Jong, MCM, Kemp, B 2004a. Phenotypic selection for residual feed intake and its effect on humoral immune responses in growing layer hens. Poultry Science 83, 1602–1609.CrossRefGoogle ScholarPubMed
Van Eerden, E, Van Den Brand, H, Reilingh, GD, Parmentier, HK, de Jong, MCM, Kemp, B 2004b. Residual feed intake and its effect on Salmonella enteritidis infection in growing layer hens. Poultry Science 83, 1904–1910.CrossRefGoogle ScholarPubMed
van Milgen, J, Bernier, JF, Lecozler, Y, Dubois, S, Noblet, J 1998. Major determinants of fasting heat production and energetic cost of activity in growing pigs of different body weight and breed/castration combination. British Journal of Nutrition 79, 509–517.CrossRefGoogle ScholarPubMed
van Milgen, J, Noblet, J 2003. Partitioning of energy to heat, protein, and fat in growing pigs. Journal of Animal Science 81 (E-supplement), E86–E93.Google Scholar
Webel, DM, Johnson, RW, Baker, DH 1998a. Lipopolysaccharide-induced reductions in body weight gain and food intake do not reduce the efficiency of arginine utilisation for whole-body protein accretion in the chick. Poultry Science 77, 1893–1898.CrossRefGoogle Scholar
Webel, DM, Johnson, RW, Baker, DH 1998b. Lipopolysaccharide-induced reductions in food intake do not reduce the efficiency of lysine and threonine utilisation for protein accretion in chickens. Journal of Nutrition 128, 1760–1766.CrossRefGoogle Scholar
Wellock, IJ, Emmans, GC, Kyriazakis, I 2003. Modelling the effects of the thermal environment and dietary composition on pig performance: model logic and concepts. Animal Science 77, 255–266.CrossRefGoogle Scholar
Whittemore, CT 1983. Development of recommended energy and protein allowances for growing pigs. Agricultural Systems 11, 159–186.CrossRefGoogle Scholar
Wilkie, BN, Mallard, BA 1998. Multi-trait selection for immune response: a possible alternative strategy for enhanced livestock health and productivity. In Progress in pig science (ed. J Wiseman), pp. 29–38. Nottingham University Press, Nottingham.Google Scholar
Williams, NH, Stahly, TS, Zimmerman, DR 1997a. Effect of chronic immune system activation on the rate, efficiency and composition of growth and lysine needs of pigs fed from 6 to 27 kg. Journal of Animal Science 75, 2463–2471.CrossRefGoogle Scholar
Williams, NH, Stahly, TS, Zimmerman, DR 1997b. Effect of chronic immune system activation on body nitrogen retention, partial efficiency of lysine utilisation, and lysine needs of pigs. Journal of Animal Science 75, 2472–2480.CrossRefGoogle ScholarPubMed
Williams, NH, Stahly, TS, Zimmerman, DR 1997c. Effect of chronic immune system activation on the growth and lysine needs of pigs fed from 6 to 112 kg. Journal of Animal Science 75, 2481–2496.CrossRefGoogle Scholar
Williams, AG, Audsley, E, Sandars, DI 2006. Determining the environmental burdens and resource use in the production of agricultural and horticultural commodities. Main Report. Defra Research Project ISO205. Cranfield University and Defra, Bedford.Google Scholar
Windisch, W, Gotterbarm, GG, Roth, FX, Schams, D, Kirchgessner, M 2000. Effect of genetic provenience of pigs (German Landrace, Pietrain) on parameter of protein metabolism. Züchtungskunde 72, 379–388.Google Scholar
Yunis, R, Ben-David, A, Heller, ED, Cahaner, A 2000. Immunocompetence and viability under commercial conditions of broiler groups differing in growth rate and in antibody response to Escherichia coli vaccine. Poultry Science 79, 810–816.CrossRefGoogle Scholar
Zhang, W, Aggrey, SE, Pesti, GM, Edwards, HM, Bakalli, RI 2003. Genetics of phytate phosphorus bioavailability: heritability and genetic correlations with growth and feed utilization traits in a randombred chicken population. Poultry Science 82, 1075–1079.CrossRefGoogle Scholar
Zhang, W, Aggrey, SE, Pesti, GM, Bakalli, RI, Edwards, HM 2005. Genetic analysis on the direct response to divergent selection for phytate phosphorus bioavailability in a random bred chicken population. Poultry Science 84, 370–375.CrossRefGoogle Scholar