Effect of heat stress on amino acid digestibility and transporters in meat-type chickens.
The present study was conducted to investigate the effect of heat stress (HS) on performance, digestibility, and molecular transporters of amino acids in broilers. Cobb 500 chicks were raised from hatch till 13 d in floor pens. At d 14, 48 birds were randomly and equally divided between a control group (25°C) and a HS treatment group (35°C). Birds in both treatment classes were individually caged and fed ad libitum on a diet containing 18.7% CP and 3,560 Kcal ME/Kg. Five birds per treatment at one and 12 d post treatment were euthanized and the Pectoralis major (P. major) and ileum were sampled for gene expression analysis. At d 33, ileal contents were collected and used for digestibility analysis. Broilers under HS had reduced growth and feed intake compared to controls. Although the apparent ileal digestibility (AID) was consistently higher for all amino acids in the HS group, it was not significant except for hydroxylysine. The amino acid consumption and retention were significantly lower in the HS group when compared to the control group. Meanwhile, the retention of amino acids per BWG was higher in the HS group when compared to the control group except for hydroxylysine and ornithine. The dynamics of amino acid transporters in the P. major and ileum was influenced by HS. In P. major and ileum tissues at d one, transporters SNAT1, SNAT2, SNAT7, TAT1, and b0,+AT, were down-regulated in the HS group. Meanwhile, LAT4 and B0AT were down-regulated only in the P. major in the treatment group. The amino acid transporters B0AT and SNAT7 at d 12 post HS were down-regulated in the P. major and ileum, but SNAT2 was down-regulated only in the ileum and TAT1 was down-regulated only in the P. major compared with the control group. These changes in amino acid transporters may explain the reduced growth in meat type chickens under heat stress.
NutriGenomics Laboratory, Department of Poultry Science, University of Georgia, Athens 30602.|Department of Animal and Poultry Production, Damanhour University, Damanhour, Al-Behira, Egypt.
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Habashy
NutriGenomics Laboratory, Department of Poultry Science, University of Georgia, Athens 30602.
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Milfort
Department of Animal Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
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Adomako
Department of Animal and Poultry Production, Damanhour University, Damanhour, Al-Behira, Egypt.|Arid Land Agriculture Department, King Abdulaziz University, Jeddah, Saudi Arabia.
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Attia
Department of Animal and Dairy Sciences, University of Georgia, Athens 30602.
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Rekaya
NutriGenomics Laboratory, Department of Poultry Science, University of Georgia, Athens 30602.
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Aggrey
D026905:Amino Acid Transport Systems / Q000235:genetics* / Q000378:metabolism; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D030161:Avian Proteins / Q000235:genetics* / Q000378:metabolism; D002645:Chickens / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D004063:Digestion / Q000502:physiology*; D020869:Gene Expression Profiling; D006358:Hot Temperature / Q000009:adverse effects*; D007082:Ileum / Q000378:metabolism*; D008297:Male; D010369:Pectoralis Muscles / Q000378:metabolism*; D011897:Random Allocation
D026905:Amino Acid Transport Systems; D030161:Avian Proteins
amino acid transporters; digestibility, Pectoralis major; heat stress; ileum