J Anim Sci. 2017 Dec;95(12):5516-5523. doi: 10.2527/jas2017.1982.
Two 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio for growing pigs; 1 experiment fed diets supplemented with or without an antibiotic. The primary response variables in both experiments were ADG, ADFI, G:F, and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys ratio detected using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with an antibiotic. This experiment used 120 crossbred pigs that were blocked by sex and initial BW (24.13 ± 2.72 kg) and allotted to 6 SID Trp:Lys ratios in 4 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (13.08%, 14.06%, 15.04%, 17.00%, 18.95%, and 20.91%) with a constant SID Lys level of 0.655%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.05) and quadratically ( < 0.05). Linear broken-line analysis yielded optimum SID Trp:Lys ratios of 17.93% ( < 0.001) and 16.17% ( = 0.009) for ADG and PUN, respectively, resulting in a mean optimum SID Trp:Lys ratio of 17.05%. Experiment 2 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. It used a total of 324 crossbred pigs (initial BW: 30.81 ± 3.56 kg) that were allotted to 6 SID Trp:Lys ratios in 6 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (12.52%, 14.86%, 17.20%, 19.54%, 21.88%, and 24.22%) with a constant SID Lys level of 0.67%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.001) and quadratically ( < 0.001) regardless of antibiotic inclusion. There were no differences by the antibiotic treatment in ADG, ADFI, G:F, or PUN concentrations ( > 0.49) and no interactions between antibiotics and Trp:Lys ratios ( > 0.29). When the data for all pigs were pooled for the various Trp:Lys ratios, the optimum SID Trp:Lys ratios for ADG and PUN based on linear broken-line analysis were 14.58% ( < 0.001) and 14.54% ( < 0.001), respectively, resulting in an optimum SID Trp:Lys ratio of 14.56% as the mean of the determined optima for ADG and PUN responses. These results demonstrate that the optimum SID Trp:Lys ratio for 30- to 50-kg growing pigs is not impacted by the dietary inclusion of an antibiotic as long as the diets are formulated on an SID AA basis.
两个 21 天试验旨在确定生长猪的标准化回肠可消化（SID）色氨酸：赖氨酸最佳比例；其中一个试验添加或不添加抗生素的日粮。两个试验的主要响应变量均为 ADG、ADFI、G:F 和血浆尿素氮（PUN）浓度，使用折线分析检测最佳 SID 色氨酸：赖氨酸比例。试验 1 评估了添加抗生素日粮中生长猪的最佳 SID 色氨酸：赖氨酸比例。该试验使用了 120 头杂交猪，根据性别和初始体重（24.13±2.72kg）进行分组，并在 4 个重复中分配到 6 个 SID 色氨酸：赖氨酸比例。通过添加结晶色氨酸来配制日粮，以创建 6 个 SID 色氨酸：赖氨酸比例（13.08%、14.06%、15.04%、17.00%、18.95%和 20.91%），SID 赖氨酸水平保持在 0.655%不变。随着 SID 色氨酸：赖氨酸比例的增加，ADG、ADFI 和 G:F 线性增加（<0.05），PUN 浓度线性和二次（<0.05）降低。线性折线分析得出 ADG 和 PUN 的最佳 SID 色氨酸：赖氨酸比例分别为 17.93%（<0.001）和 16.17%（=0.009），平均最佳 SID 色氨酸：赖氨酸比例为 17.05%。试验 2 评估了添加或不添加抗生素日粮中生长猪的最佳 SID 色氨酸：赖氨酸比例。总共使用了 324 头杂交猪（初始体重：30.81±3.56kg），在 6 个重复中分配到 6 个 SID 色氨酸：赖氨酸比例。通过添加结晶色氨酸来配制日粮，以创建 6 个 SID 色氨酸：赖氨酸比例（12.52%、14.86%、17.20%、19.54%、21.88%和 24.22%），SID 赖氨酸水平保持在 0.67%不变。随着 SID 色氨酸：赖氨酸比例的增加，ADG、ADFI 和 G:F 线性增加（<0.001），PUN 浓度线性和二次（<0.001）降低。无论抗生素添加与否，抗生素处理对 ADG、ADFI、G:F 或 PUN 浓度均无差异（>0.49），抗生素和色氨酸：赖氨酸比例之间也无相互作用（>0.29）。当将不同色氨酸：赖氨酸比例下所有猪的数据汇总时，基于线性折线分析，ADG 和 PUN 的最佳 SID 色氨酸：赖氨酸比例分别为 14.58%（<0.001）和 14.54%（<0.001），这导致最佳 SID 色氨酸：赖氨酸比例为 14.56%，为 ADG 和 PUN 响应确定的最佳值的平均值。这些结果表明，只要日粮是基于 SID AA 配制的，添加抗生素不会影响 30-50kg 生长猪的最佳 SID 色氨酸：赖氨酸比例。
