Effects of dietary L-isoleucine on laying performance and immunomodulation of laying hens.
Isoleucine may be a limiting amino acid for laying hens fed diets with a lowered protein level. An experiment was conducted to examine laying performance and the immune function of laying hens provided diets varying in digestible isoleucine levels during the peak production period. A total number of 400 Lohmann Brown laying hens, 28 wk of age, were allocated to 5 dietary treatment groups, each of which included 5 replicates of 16 hens per replicate (4 cages / replicate; 80 hens / treatment). L-isoleucine was added to the experimental diet (14% CP) containing synthetic amino (methionine, lysine, threonine, tryptophan, and valine) by zero, 1.0, 2.0, 3.0, and 4.0 g/kg, corresponding to 0.54%, 0.64%, 0.74%, 0.84, and 0.94% digestible isoleucine, respectively. At the end of the experiment (wk 40), dietary isoleucine did not affect laying performance or egg quality. Serum albumin concentration increased quadratically (P < 0.05) in response to digestible dietary isoleucine at 0.74%. Serum free isoleucine and lysine increased (P < 0.05) in response to digestible dietary isoleucine at 0.74%. Digestible dietary isoleucine levels did not affect the serum concentrations of total antioxidative capability (T-AOC), total superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), and CuZn-superoxide dismutase (CuZn-SOD). There was no significant (P > 0.05) response of excess digestible isoleucine level on the serum level of IgG, IgA, or IgM. In addition, dietary isoleucine levels did not affect the concentrations of secretory immunoglobulin A (sIgA), tumor necrosis factor alpha (TNFα), or interleukin (IL-2 and IL-6) in the ileum. Also, expressions of ileal MUC2 mRNA, sIgA mRNA, and IL-1β mRNA were not changed (P > 0.05) by excess digestible isoleucine level. Furthermore, excess digestible isoleucine level did not change mRNA expression of ileal tight junction protein (claudin-1 and occludin). No effect occurred when isoleucine was supplemented, suggesting that it is not a limiting amino acid in the low crude protein diet on laying performance and intestinal mucosal immune.
Feed Science Institute, Zhejiang University, Hangzhou 310029, China.
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Feed Science Institute, Zhejiang University, Hangzhou 310029, China Poultry Production Department, Faculty of Agriculture, Mansoura University, Al-Mansoura 35516, Egypt azzam@mans.edu.eg xtzou@zju.edu.cn.
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Azzam
Feed Science Institute, Zhejiang University, Hangzhou 310029, China azzam@mans.edu.eg xtzou@zju.edu.cn.
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Zou
D000596:Amino Acids / Q000097:blood; D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002645:Chickens / Q000276:immunology / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D005260:Female; D018928:Immunity, Mucosal / Q000276:immunology*; D056747:Immunomodulation / Q000502:physiology*; D007422:Intestines / Q000276:immunology; D007532:Isoleucine / Q000276:immunology*; D011897:Random Allocation; D012098:Reproduction
D000596:Amino Acids; D000975:Antioxidants; D007532:Isoleucine
L-isoleucine; intestinal mucosal immune; laying hens; laying performance