title: Methionine improves the performance and breast muscle growth of broilers with lower hatching weight by altering the expression of genes associated with the insulin-like growth factor-I signalling pathway.
abstract: The present study aimed to investigate the responses of broilers with different hatching weights (HW) to dietary methionine (Met). A total of 192 1-d-old Arbor Acres broiler chicks with different HW (heavy: 48·3 (sem 0·1) g and light: 41·7 (sem 0·1) g) were allocated to a 2 (HW) × 2 (Met) factorial arrangement with six replicates of eight chicks. Control starter (1-21 d) and finisher (22-42 d) diets contained 0·50 and 0·43 % Met, respectively. Corresponding values for a high-Met treatment were 0·60 and 0·53 %. Light chicks had poorer (P< 0·05) growth performance and breast muscle weight and lower (P< 0·05) insulin-like growth factor-I (IGF-I) concentration and mRNA level in breast muscle than heavy chicks when both were fed the control diets. High-Met diets improved performance and promoted breast muscle growth and IGF-I concentration in light chicks (P< 0·05). Increased IGF-I and target of rapamycin (TOR) mRNA levels as well as decreased eIF4E-binding protein 1 (4EBP1), atrogin-1 and forkhead box O 4 (FOXO4) mRNA levels were induced by high-Met diets in light chicks (P< 0·05). In conclusion, the Met requirement of broilers might depend on their HW and Met levels used in the control diets in the present study were adequate for heavy chicks but inadequate for light chicks, resulting in poorer performance and breast muscle growth, which were improved by increasing dietary Met supply presumably through alterations in IGF-I synthesis and gene expression of the TOR/4EBP1 and FOXO4/atrogin-1 pathway.
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wen
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, People's Republic of China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wu
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, People's Republic of China.
authors.forename: Yueping
authors.initials: Y
authors.lastname: Chen
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, People's Republic of China.
authors.forename: Tian
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Animal Science and Technology, Nanjing Agricultural University, No. 1 Weigang, Nanjing, Jiangsu 210095, People's Republic of China.
authors.forename: Yanmin
authors.initials: Y
authors.lastname: Zhou
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000254:growth & development*; D004032:Diet / Q000662:veterinary; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008715:Methionine / Q000494:pharmacology*; D018482:Muscle, Skeletal / Q000254:growth & development*; D015398:Signal Transduction
chemical_list: D007334:Insulin-Like Growth Factor I; D008715:Methionine