日粮苏氨酸水平对肉鸡生产性能、机体抗氧化性能和免疫机能的影响

旨在研究日粮不同苏氨酸水平对肉鸡生产和免疫的影响,为苏氨酸在肉鸡生产中的应用提供依据。将432只体质量相近的1日龄健康AA肉鸡随机分成4组,每组6个重复,每个重复18只鸡,分别饲喂苏氨酸水平为NRC(1994)标准推荐量的85%、100%、125%和150%的日粮,采样并测定肉鸡的生长性能、血清生化指标、机体抗氧化指标和免疫指标。结果表明,日粮不同苏氨酸水平显著影响肉鸡平均日增量和耗料增量比,但对平均日采食量的影响不显著,其中,100%NRC组生产性能最佳;日粮苏氨酸水平显著影响血清谷胱甘肽过氧化物酶及总超氧化物歧化酶的活性,以125%NRC组活性最高;日粮过量苏氨酸水平显著提高血清中谷草转氨酶和谷丙转氨酶活性,显著增加血清中尿酸的浓度;日粮中125%NRC苏氨酸水平能够显著增加血清中总蛋白、球蛋白质量浓度和肉鸡的脾脏指数、法氏囊指数及胸腺指数。日粮苏氨酸水平对21日龄、35日龄和42日龄肉鸡新城疫抗体滴度有显著影响,且抗体水平以125%NRC组最高。总之,日粮苏氨酸水平为NRC(1994)标准推荐量的100%时,肉鸡可获得最佳的生产性能;日粮中125%NRC苏氨酸水平能增强机体的抗氧化能力和免疫机能。

Effects of Dietary Threonine Levels on Growth Performance, Antioxidant Capacities and Immune Function of Broiler Chickens

The study was conducted to investigate the impacts of dietary threonine levels on growth performance and immune function in broilers chicken. Four hundred and thirty two 1 day old AA broilers were randomly allocated to four dietary treatments with six replicates of 18 broilers each. Dietary threonine levels were 85%, 100%, 125%, and 150% of NRC recommendation for broilers, respectively. Growth performance, serum biochemical indexes, antioxidant and immune indexes were determined. The results showed that dietary threonine levels had significant effect on average daily gain and feed conversion ratio, whereas average daily feed intake was not influenced by dietary threonine level, and threonine level in the NRC recommendations (1994)that was optimum for growth performance. The threonine levels had significant effect on serum glutathione peroxidase and totalserum super oxide dismutase, and the highest activities of total super oxide dismutase and glutathione peroxidase were obtained at 125% threonine level. Excess dietary threonine level triggered plasma aspartate aminotransferase and alanine aminotransferase activities, increased content of uric acid. Excess dietary threonine level (about 125%) could increase excretion of globulin and total protein in serum, and improved spleen index, thymus index and bursal index. On 21d, 35 d and 42 d, the antibody concentrations of newcastle disease virus showed significant response to different graded concentrations of threonine, and the highest serum antibody concentrations of newcastle disease virus were obtained at 125% dietary threonine level. In conclusion, threonine level in the NRCrecommendations (1994) was optimum for growth performance, and 125% of threonine level in the NRC recommendations (1994) had better effects on antioxidant function, and immune function of broilers.