標準回腸可消化色氨酸和賴氨酸的比例對保育豬生長性能的影響

　　2015. J. Anim.Sci. 93(8):3909-3918
　　標準回腸可消化色氨酸和賴氨酸的比例對保育豬生長性能的影響
　　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

　　本論文開展兩個試驗確定保育豬標準回腸可消化色氨酸（SID色氨酸）需要量。試驗日糧配方將賴氨酸設計為第二限制性氨基酸。試驗一選用255保育仔豬（PIC 327 × 1050，初始重6.3±0.15kg），隨機分為7個處理組，每個處理7圈，每圈6-7頭仔豬，試驗期14天。試驗日糧SID色氨酸:賴氨酸分別為14.7、16.5、18.4、20.3、22.1、24.0%，SID賴氨酸含量為1.3%。

試驗二（11-20kg體重）選用1088頭仔豬（PIC 337 × 1050，初始重11.2±1.35kg），按平均體重隨機分為7個處理組，每個處理6圈，每圈24-27頭仔豬，試驗期21天。試驗日糧SID色氨酸:賴氨酸分別為14.5、16.5、18.0、19.5、21.0、22.5、24.5%，SID賴氨酸含量為0.97%，日糧中添加30%DDGS。所有試驗使用帶非均勻殘余方差的一般線性混合模型分析。異方差模型包括線性折線模型（BLL）、二次線性折線模型（BLQ）、二次多項式模型（QP）。使用貝葉斯準則判斷最準確的生長性能的預測模型。

試驗一（6-11kg體重階段）結果表明隨著SID色氨酸:賴氨酸提高，日增重和增重耗料比（G:F）都有線性提高（P＜0.05）。二次多項式模型能更準確的預測日增重，最佳SID色氨酸:賴氨酸為23.9%（95%置信區(qū)間為14.7-24.0%）。線性折線模型能更好的預測增重耗料比（G:F），最佳SID色氨酸:賴氨酸為20.4%（95%置信區(qū)間為14.3-26.5%）。

試驗二（11-20kg體重階段）結果表明隨SID色氨酸:賴氨酸的提高，日增重和增重耗料比也有二次線性增加（P＜0.05）。二次多項式模型能更準確的預測日增重，最佳SID色氨酸:賴氨酸為21.2%（95%置信區(qū)間為20.5-21.9%）。線性折線模型能更好的預測增重耗料比（G:F），最佳SID色氨酸:賴氨酸為20.4%（95%置信區(qū)間為14.3-26.5%）。線性折線模型（BLL）和二次線性折線模型（BLQ）都能很好的預測增重耗料比，最佳SID色氨酸:賴氨酸分別為16.6%和17.1%（95%置信區(qū)間分別為16.0-17.3%和16.6-17.7%）。總之，試驗一預測最佳SID色氨酸:賴氨酸為20.4%（最佳增重耗料比）至23.9%（最佳生長性能），而試驗二預測最佳SID色氨酸:賴氨酸為16.6%（最佳增重耗料比）至21.2%（最佳生長性能）.這些試驗結果表明NRC（2012）的推薦標準可能低估了11-20kg保育豬的SID色氨酸:賴氨酸需要。

　　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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