标准回肠可消化色氨酸和赖氨酸的比例对保育猪生长性能的影响

畜牧编辑

　　2015. J. Anim.Sci. 93(8):3909-3918
　　标准回肠可消化色氨酸和赖氨酸的比例对保育猪生长性能的影响
　　M. A. D.Gonçalves, S. Nitikanchana, M. D. Tokach, S. S. Dritz, N. M. Bello, R. D.Goodband, K. J. Touchette, J. L. Usry, J. M. DeRouchey和J. C. Woodworth

　　本论文开展两个试验确定保育猪标准回肠可消化色氨酸（SID色氨酸）需要量。试验日粮配方将赖氨酸设计为第二限制性氨基酸。试验一选用255保育仔猪（PIC 327 × 1050，初始重6.3±0.15kg），随机分为7个处理组，每个处理7圈，每圈6-7头仔猪，试验期14天。试验日粮SID色氨酸:赖氨酸分别为14.7、16.5、18.4、20.3、22.1、24.0%，SID赖氨酸含量为1.3%。

试验二（11-20kg体重）选用1088头仔猪（PIC 337 × 1050，初始重11.2±1.35kg），按平均体重随机分为7个处理组，每个处理6圈，每圈24-27头仔猪，试验期21天。试验日粮SID色氨酸:赖氨酸分别为14.5、16.5、18.0、19.5、21.0、22.5、24.5%，SID赖氨酸含量为0.97%，日粮中添加30%DDGS。所有试验使用带非均匀残余方差的一般线性混合模型分析。异方差模型包括线性折线模型（BLL）、二次线性折线模型（BLQ）、二次多项式模型（QP）。使用贝叶斯准则判断最准确的生长性能的预测模型。

试验一（6-11kg体重阶段）结果表明随着SID色氨酸:赖氨酸提高，日增重和增重耗料比（G:F）都有线性提高（P＜0.05）。二次多项式模型能更准确的预测日增重，最佳SID色氨酸:赖氨酸为23.9%（95%置信区间为14.7-24.0%）。线性折线模型能更好的预测增重耗料比（G:F），最佳SID色氨酸:赖氨酸为20.4%（95%置信区间为14.3-26.5%）。

试验二（11-20kg体重阶段）结果表明随SID色氨酸:赖氨酸的提高，日增重和增重耗料比也有二次线性增加（P＜0.05）。二次多项式模型能更准确的预测日增重，最佳SID色氨酸:赖氨酸为21.2%（95%置信区间为20.5-21.9%）。线性折线模型能更好的预测增重耗料比（G:F），最佳SID色氨酸:赖氨酸为20.4%（95%置信区间为14.3-26.5%）。线性折线模型（BLL）和二次线性折线模型（BLQ）都能很好的预测增重耗料比，最佳SID色氨酸:赖氨酸分别为16.6%和17.1%（95%置信区间分别为16.0-17.3%和16.6-17.7%）。总之，试验一预测最佳SID色氨酸:赖氨酸为20.4%（最佳增重耗料比）至23.9%（最佳生长性能），而试验二预测最佳SID色氨酸:赖氨酸为16.6%（最佳增重耗料比）至21.2%（最佳生长性能）.这些试验结果表明NRC（2012）的推荐标准可能低估了11-20kg保育猪的SID色氨酸:赖氨酸需要。

　　Effects of standardized ileal digestible tryptophan: lysine ratio on growth performance of nursery pigs

　　M. A. D.Gonçalves, S. Nitikanchana, M. D. Tokach, S. S. Dritz, N. M. Bello, R. D.Goodband, K. J. Touchette, J. L. Usry, J. M. DeRouchey and J. C. Woodworth

　　Two experiments were conducted to estimate the standardized ileal digestible (SID) Trp:Lys ratio requirement for growth performance of nursery pigs. Experimental diets were formulated to ensure that lysine was the second limiting AA throughout the experiments. In Exp. 1 (6 to 10 kg BW), 255 nursery pigs (PIC327 × 1050, initially 6.3 ± 0.15 kg, mean ± SD) arranged in pens of 6 or 7 pigs were blocked by pen weight and assigned to experimental diets (7 pens/diet) consisting of SID Trp:Lys ratios of 14.7%, 16.5%, 18.4%, 20.3%, 22.1%, and 24.0% for 14 d with 1.30% SID Lys. In Exp. 2 (11 to 20 kg BW), 1,088 pigs (PIC337 × 1050, initially 11.2 kg ± 1.35 BW, mean ± SD) arranged in pens of 24 to 27 pigs were blocked by average pig weight and assigned to experimental diets(6 pens/diet) consisting of SID Trp:Lys ratios of 14.5%, 16.5%, 18.0%, 19.5%,21.0%, 22.5%, and 24.5% for 21 d with 30% dried distillers grains with solubles and 0.97% SID Lys. Each experiment was analyzed using general linear mixed models with heterogeneous residual variances. Competing heteroskedastic models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). For each response, the best-fitting model was selected using Bayesian information criterion. In Exp. 1 (6 to 10 kg BW), increasing SID Trp:Lys ratio linearly increased (P < 0.05) ADG and G:F. For ADG, thebest-fitting model was a QP in which the maximum ADG was estimated at 23.9%(95% confidence interval [CI]: [<14.7%, >24.0%]) SID Trp:Lys ratio. For G:F,the best-fitting model was a BLL in which the maximum G:F was estimated at 20.4% (95% CI: [14.3%, 26.5%]) SID Trp:Lys. In Exp. 2 (11 to 20 kg BW),increasing SID Trp:Lys ratio increased (P < 0.05) ADG and G:F in a quadratic manner. For ADG, the best-fitting model was a QP in which the maximum ADG was estimated at 21.2% (95% CI: [20.5%, 21.9%]) SID Trp:Lys. For G:F, BLL and BLQ models had comparable fit and estimated SID Trp:Lys requirements at 16.6% (95%CI: [16.0%, 17.3%]) and 17.1% (95% CI: [16.6%, 17.7%]), respectively. In conclusion, the estimated SID Trp:Lys requirement in Exp. 1 ranged from 20.4% for maximum G:F to 23.9% for maximum ADG, whereas in Exp. 2 it ranged from 16.6% for maximum G:F to 21.2% for maximum ADG. These results suggest that standard NRC (2012) recommendations may underestimate the SID Trp:Lys requirement for nursery pigs from 11 to 20 kg BW。

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