State Key Laboratory of Animal Nutrition, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Poult Sci. 2018 Jan 1;97(1):262-266. doi: 10.3382/ps/pex219.
The present study was conducted to investigate the effects of dietary crude protein (CP) on threonine requirements by determining the interactions of dietary CP levels (16.0, 17.5, 19.0, 20.5, and 22.0%) and supplemental threonine levels (0, 0.07, 0.14, 0.21, and 0.28%) on growth performance of Pekin ducks from 1 to 14 days of age. A total of 1,200 one-day-old male Pekin ducks was randomly allotted to 1 of 25 dietary treatments with 6 replicate pens of 8 birds per pen for each treatment. The results showed that dietary CP and threonine levels affected the average daily feed intake (ADFI, P < 0.0001), average daily gain (ADG, P < 0.0001), ratio of feed/gain (F/G, P < 0.0001) of Pekin ducks, and had an interactions on the ADFI, ADG, F/G (P < 0.0001). The ADG was increased linearly (P < 0.002) and then reached a plateau as the dietary threonine increased at all CP diets. According to the estimation of broken-line models, the dietary threonine requirements at 16.0, 17.5, 19.0, 20.5, and 22.0% CP diets for optimal ADG of ducks were 0.56, 0.61, 0.60, 0.63, and 0.67% when expressed as percentage of diet, or 44.22, 47.65, 47.50, 48.30, and 50.39% when expressed as percentage of dietary lysine, or 3.45, 3.44, 3.12, 3.27, and 2.98% when expressed as percentage of dietary CP, respectively. Threonine requirements of Pekin ducks from 1 to 14 days of age were affected by dietary CP levels according to the Student t test results, but had no difference among the moderate CP level diets (17.5, 19, and 20.5%) when expressed as a percentage of diet or dietary lysine. It was concluded that dietary CP levels affected the threonine requirements of Pekin ducks from 1 to 14 days of age, but threonine requirements were constant within the limiting CP level range (17.5 to 20.5%) with a good balance of dietary amino acid, and were approximately 0.60 to 0.63% of diet or 47.5 to 48.3% of dietary lysine.
本研究旨在通过确定饲粮粗蛋白（CP）水平（16.0、17.5、19.0、20.5 和 22.0%）和补充苏氨酸水平（0、0.07、0.14、0.21 和 0.28%）之间的相互作用，来研究饲粮 CP 水平对 114 日龄北京鸭苏氨酸需要量的影响。选用 1200 只 1 日龄雄性北京鸭，随机分成 25 个饲粮处理组，每个处理组设 6 个重复，每个重复 8 只鸭。结果表明，饲粮 CP 和苏氨酸水平影响北京鸭的平均日采食量（ADFI，P＜0.0001）、平均日增重（ADG，P＜0.0001）、料重比（F/G，P＜0.0001），且二者对 ADFI、ADG、F/G 存在互作效应（P＜0.0001）。随着饲粮苏氨酸水平的增加，ADG 呈线性增加（P＜0.002），然后达到平台期。根据折线模型估计，16.0、17.5、19.0、20.5 和 22.0%CP 饲粮下，北京鸭获得最佳 ADG 时的饲粮苏氨酸需要量分别为 0.56%、0.61%、0.60%、0.63%和 0.67%，占饲粮的百分比；或 44.22%、47.65%、47.50%、48.30%和 50.39%，占饲粮赖氨酸的百分比；或 3.45%、3.44%、3.12%、3.27%和 2.98%，占饲粮 CP 的百分比。根据学生 t 检验结果，饲粮 CP 水平影响 114 日龄北京鸭的苏氨酸需要量，但当以饲粮或饲粮赖氨酸的百分比表示时，中等 CP 水平（17.5%、19%和 20.5%）饲粮之间的苏氨酸需要量没有差异。由此可知，饲粮 CP 水平影响 114 日龄北京鸭的苏氨酸需要量，但在限制 CP 水平范围内（17.520.5%），饲粮氨基酸平衡良好，苏氨酸需要量保持不变，约占饲粮的 0.60%0.63%或饲粮赖氨酸的 47.5%48.3%。
