0-4周龄京红蛋鸡饲粮蛋氨酸需要量研究

【目的】研究中国新培育的京红蛋鸡（0—4周龄）饲粮蛋氨酸需要量。【方法】选取300只体重相近、健康的1日龄京红蛋鸡，采用单因素完全随机试验设计，随机分5个处理，饲粮蛋氨酸水平分别为0.2%、0.3%、0.4%、0.5%和0.6%，每处理5个重复，每重复12只鸡。试期28 d。在14 d随机从每个重复选2只鸡空腹12 h屠宰，取胸腺、脾脏和法氏囊，计算免疫指数；在28 d随机从每个重复选2只鸡空腹12 h屠宰，分别取免疫和消化器官，计算相应指数。【结果】（1）饲粮蛋氨酸水平未见显著影响雏鸡采食量(P＞0.05)，但显著影响其增重(P＜0.05)，其中0.4% Met组鸡增重最大，且该组雏鸡ADG为8.31 g•d-1，显著高于0.2%、0.5%和0.6% Met组（P＜0.05），且呈二次曲线升高趋势；显著影响料重比(P＜0.05)，其中0.5% Met组最佳（2.13﹕1），显著低于0.2%和0.3% Met组（P＜0.05），呈二次曲线趋势降低；显著影响体重，且呈现二次曲线升高，0.4% Met组体重为268.70g，显著高于0.2%、0.5%和0.6% Met组（P＜0.05）；群体均匀度也呈现二次曲线升高，0.5% Met组最佳（85.19%），显著高于其它处理组(P＞0.05)。（2）14 d，饲粮蛋氨酸水平未显著影响雏鸡胸腺指数和法氏囊指数(P＞0.05)，显著影响脾脏指数(P＜0.05)，0.4% Met组最大；28 d，鸡胸腺、脾脏和法氏囊指数均随饲粮Met水平呈显著正相关关系(P＜0.05)，且呈先升后降的趋势。其中，0.4% Met组脾脏和法氏囊指数最大，0.5% Met组胸腺指数最大。（3）饲粮Met水平未显著影响胰腺指数和十二指肠相对长度(P＞0.05)，显著影响蛋鸡十二指肠、空肠和回肠重量指数和空肠回肠长度指数(P＜0.05)。随饲粮蛋氨酸水平升高，胰腺指数呈先升后降趋势，十二指肠、空肠和回肠重量指数和空肠、回肠长度指数均呈先降后升趋势。0.3% Met组十二指肠指数显著低于0.2%、0.5%和0.6% Met组(P＜0.05)；0.4% Met组的空肠指数显著低于其他Met组(P＜0.05)，0.5% Met组的空肠相对长度显著低于0.2%、0.3%和0.6% Met组(P＜0.05)；0.4% Met组的回肠指数显著低于0.6% Met组(P＜0.05)，0.3% Met组的回肠相对长度显著低于0.2%、0.5%和0.6% Met组(P＜0.05)。（4）饲粮Met水平显著影响鸡血清尿素氮、尿酸和碱性磷酸酶水平(P＜0.05)，其中0.6% Met组的雏鸡血清的血清尿素氮显著高于0.2%、0.4%和0.5% Met组(P＜0.05)，且0.5% Met组血清尿素氮最低、碱性磷酸酶水平最高(P＜0.05)；0.6% Met组尿酸显著高于其他组(P＜0.05)；但饲粮Met水平未见显著影响鸡血清白蛋白、总蛋白(P＞0.05)。5)通过对鸡体重和料重比二次曲线拟合得出饲粮Met最佳剂量为0.466%和0.507%，平均0.487%。【结论】综合鸡群增重、料重比、群体均匀度等经济指标、免疫指标、消化系统发育和血液生化指标，推荐0—4周龄京红蛋鸡饲粮蛋氨酸需要量为0.49%。

Studies on Dietary Methionine Requirement of Jinghong Laying Hens from Hatch to the Age of 4 Weeks

【Objective】Dietary methionine(Met) levels for China’s new cultivation of Jinghong laying hens from hatch to the age of 4 weeks were studied.【Method】The trial had adopted one-factor completely random design. Three hundred 1-day-old Jinghong laying hens from a commercial supplier in YuKou poultry were randomly allotted to 5 dietary treatment groups, and the birds in the treatment groups were fed a diet with different dietary methionine levels, respectively, i.e. 0.2% (0.2% Met), 0.3% (0.3% Met), 0.4% (0.4% Met), 0.5% (0.5% Met) and 0.6% (0.6% Met). Each treatment group consisted of 5 replicates with 5 pens per replicate and 12 birds per pen. The experiment lasted for 28 days. On 14th day, after being deprived of feed for 12 h, 2 birds selected randomly from each pen were slaughtered by neck cut and birds were eviscerated manually. The thymus, spleen and bursa of fabricius were weighed and were expressed as a percentage relative to live BW at processing. On 28th day, after being deprived of feed for 12 h, 2 birds selected randomly from each pen were slaughtered by neck cut and birds were eviscerated manually. The immune organs and digestive organs were weighed and were expressed as a percentage relative to live BW at processing.【Result】No significant differences were found in average daily feed intake (P＞0.05), but the average daily gain was significantly different (P＜0.05), and the birds in 0.4% Met group showed the maximum value with 8.31 g•d-1 and significantly higher than 0.2%, 0.5% and 0.6% Met groups (P＜0.05), with a quadratic curve of a rising trend. Besides, feed/gain ratios were also significantly affected (P＜0.05), and the 0.5% Met group was the best (2.13:1) and significantly lower than 0.2% and 0.3% Met groups (P＜0.05), with a quadratic curve of reducing trend. Body weight was significantly affected (P＜0.05), and the 0.4% Met group was the best (268.70 g) and significantly higher than 0.2%, 0.5% and 0.6% Met groups (P＜0.05), with a quadratic curve of rising trend. Community evenness also showed a tendency of a quadratic curve of rising, the 0.5%Met group (85.19%) was significantly higher than the other groups (P＜0.05). By the end of 2nd week, no-significant influence on the relative weights of the thymus and bursa of fabricius (P＞0.05) was found among different groups. There was a significant impact on the relative weights of the spleen (P＜0.05), the 0.4% Met group reached the maximum. By the end of the 4th week, the relative weights of the thymus, spleen and bursa of fabricius showed a significant positive correlation (P＜0.05) with dietary Met levels and all values had a rise-fall tendency. The relative weights of the spleen and bursa of fabricius in 0.4% Met group were the largest; the thymus index in 0.5% Met group was the largest. No significant differences were found in pancreas index and the relative lengths of the duodenum (P＞0.05), but the relative weights of the duodenum, jejunum and ileumor or the relative lengths of the jejunum and ileum were significantly different (P＜0.05). With the increase of methionine, except the relative weights of pancreas which showed a rise-fall tendency, the relative weights of the duodenum, jejunum and ileumor or the relative lengths of the jejunum and ileum had shown a fall-rise tendency. The relative weights of the duodenum in 0.3% Met group were significantly lower than 0.2%, 0.5% and 0.6% Met groups (P＜0.05). The relative weights of the jejunum in 0.4% Met group were significantly lower than other Met groups (P＜0.05). The relative lengths of the jejunum in 0.5% Met group were significantly lower than 0.2%, 0.3% and 0.6% Met groups (P＜0.05). The relative weights of the ileumor in 0.4% Met group were significantly lower than 0.6% Met group (P＜0.05). The relative lengths of the ileumor in 0.3% Met group were significantly lower than 0.2%, 0.5% and 0.6% Met groups (P＜0.05). There were significant differences among groups in the level of serum urea nitrogen, uric acid and alkaline phosphatase (P＜0.05). The level of serum urea nitrogen in 0.6% Met group was significantly higher than 0.2%, 0.4% and 0.5% Met groups (P＜0.05). The 0.5% Met group was the minimum of serum urea nitrogen, while alkaline phosphatase was significantly higher than the other groups (P＜0.05). Uric acid in 0.6% Met group was significantly higher than the other groups (P＜0.05), but no significant differences were found in albumin, total protein by different methionine levels (P＞0.05). According to quadratic curve estimation of the weight and feed/gain ratio, the optimal methionine levels were 0.466% and 0.507%, which could be averaged to 0.487%.【Conclusion】Combined with the average daily gain, feed/gain ratio, community evenness and other economic indicators, immune index, digestive system, index of blood, the optimal methionine requirement of Jinghong laying hens of 0-4 weeks is 0.49%.