| 報告時間：2025-6-20 |
| 報告地點：Room 407 |
| 指導老師：Shuen-Ei Chen |
| 學生：YU-XUAN Wang |
| 摘要 |
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Uniformity (normally expressed as CV%; namely coefficient of variation) in broilers is an important indicator for evaluating flock management, as poor uniformity can reduce slaughter and packaging process and thus overall economic efficiency. Uniformity is influenced by factors such as breed, sex, nutrition, and management. Methionine is a sulfur-containing essential amino acid primarily metabolized in the liver. It is essential for protein synthesis, methylation, and antioxidant function. Methionine is commonly supplemented in the standard poultry diet to improve body weight gain, while the level optimal to the individuals of the whole population such as males and females remain elusive. This study aimed to investigate the effect of additional levels and durations of DL-methionine supplementation in the standard diet on the growth performance and body weight uniformity of broilers. In the study, 0.04%, 0.08%, and 0.12% of additional DL-methionine were added to commercial feed starting from either 14 or 21 day of age. Body weight and feed intake were recorded weekly and tissues were collected at day 35 for gene expression analysis. Results showed that long-term supplementation (14–35 days) with different DL-methionine levels had no significant effects on growth performance at 35 days, while short-term supplementation (21–35 days) with 0.04% and 0.12% DL-methionine significantly improved body weight gain, and feed conversion ratio. In uniformity, 0.08% DL-methionine group exhibited a lowest CV value (6.60% for short-term and 7.44% for long-term) as compared to 11.54% in the control group. Body weight distribution and percentile analysis suggested that 0.08% DL-methionine significantly improved the uniformity in female broilers, especially among small- and medium-sized birds. In contrast, male broilers showed limited improvements. Based on the analysis uniformity, only control group and the two DL-methionine groups with the best uniformity were selected for tissue analyses. Within these three groups, individuals of different sexes and body sizes were selected to further investigate the physiological effects by the treatments. Small- and medium-sized birds in the treatment groups had significantly higher breast muscle ratios than those in the control group. Regarding gene expressions, hepatic IGF-1 (insulin-like growth factor) protein levels were significantly higher in medium-sized males from the short-term group and medium-sized females from the long-term group than their respective control counterparts. Myostatin (MSTN) gene expression was generally higher in small-sized birds but was significantly reduced in small-sized females receiving long-term supplementation. In conclusion, supplementation with additional 0.08% DL-methionine effectively improved broiler body weight uniformity, particularly in female and small- to medium-sized birds, through modulation of growth-related gene expressions. Keywords: Broilers、Methionine、Uniformity、IGF-1、MSTN |
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