The response of performance in grower and finisher pigs to diets formulated to different tryptophan to lysine ratios

文献类型： 外文期刊

第一作者： Liu, J. B.

作者： Liu, J. B.;Yan, H. L.;Cao, S. C.;Liu, J.;Li, Z. X.;Zhang, H. F.;Liu, J. B.;Zhang, H. F.

作者机构：

关键词： Broken-line; Pig; Requirement; Standardized ileal digestible; Tryptophan to lysine ratio

期刊名称：LIVESTOCK SCIENCE （ 影响因子：1.943； 五年影响因子：2.252 ）

ISSN： 1871-1413

年卷期： 2019 年 222 卷

页码：

收录情况： SCI

摘要： Three experiments were conducted to determine the optimal dietary standardized ileal digestible (SID) Trp to Lys ratio (Trp:Lys) for grower-finisher pigs with body weight of 20-50 (Experiment (Exp.) 1), 50-80 (Exp. 2), and 80-110 kg (Exp. 3). A total of 4032 Duroc x Yorkshire x Landrace barrows and gilts were used in the experiments with a randomized complete blocked design. For each experiment, 1344 pigs were randomly assigned into 6 dietary treatments (SID Trp:Lys levels: 0.150, 0.165, 0.180, 0.195, 0.210, and 0.225) with 8 replicate pens per treatment (14 barrows and 14 gilts per pen). Synthetic Trp was used to adjust the dietary SID Trp:Lys, while the Lys content in all 6 diets remained fixed in each experiment. In Exp. 1, the average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and serum urea N (SUN) were increased quadratically (P < 0.01) as the SID Trp:Lys increased from 0.150 to 0.225. The optimal SID Trp:Lys for ADG estimated using broken-line and curvilinear-plateau models were 0.171 and 0.188, respectively. For G:F, the break-points were 0.192 and 0.207 for the linear and quadratic models, respectively. In Exp. 2, a quadratic increase was observed in ADG, ADFI, G:F, and SUN as the SID Trp:Lys increased from 0.150 to 0.225 (P < 0.05). The optimal SID Trp:Lys for ADG estimated using the broken-line and curvilinear-plateau models were 0.183 and 0.200, respectively. The break-points for G:F estimated using broken-line and curvilinear-plateau models were 0.195 and 0.213, respectively. In Exp. 3, the ADG, G:F, and SUN increased quadratically with increasing SID Trp:Lys, while ADFI increased linearly (P < 0.05). The optimal SID Trp:Lys for ADG estimated using the broken-line and curvilinear-plateau models were 0.184 and 0.201, respectively. Likewise for G:F, the best ratios were 0.174 and 0.198 for the linear and curvilinear models, respectively. In summary, the optimal Trp:Lys for ADG estimated using the broken-line model in pigs weighing 20 to 50, 50 to 80, and 80 to 110 kg were 0.171, 0.183, and 0.184, respectively. The optimal Trp:Lys for G:F estimated using the broken-line model in pigs weighing 20 to 50, 50 to 80, and 80 to 110 kg were 0.192, 0.195, and 0.174, respectively.

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