Ronald A S Navales，Jim Dunn，John K Htoo，Kevin Touchette，Robert C Thaler，Crystal L Levesque

翻译&校对：上海亘泰实业集团

       本论文开展两个试验研究初产妊娠母猪可利用赖氨酸和苏氨酸沉积为体蛋白的效率。

       试验一，选用2批共45头初产母猪（妊娠39.4±1d，体重158.0±8.0kg），进行3期氮平衡试验。母猪随机分为4个日粮处理，分别提供最大蛋白质沉积下标准回肠可消化（SID）赖氨酸日需要量（NRC 2012）的60、70、80、90%，妊娠早期（第41-52d）、中期（第68-79d）、末期（第96-107d）SID赖氨酸日需要量分别为10.44、9.6、16.04g/d。日粮代谢能为3300 kcal/kg，粗蛋白含量为11.6%，妊娠早期、中期饲喂量为2.13 kg/d，妊娠后期饲喂量为2.53 kg/d。每个试验期为12d，7d适应期，5d粪尿收集期，使用导尿管收集全部尿液，使用标记物测定粗蛋白消化率。通过NRC（2012）模型预测每个试验期全体蛋白沉积所需要的SID赖氨酸量。通过日赖氨酸沉积量和SID赖氨酸摄入量计算每个处理中赖氨酸的沉积效率。检测每个妊娠期体蛋白沉积、赖氨酸沉积、赖氨酸效率是否存在线性、二次线性效应。通过SID赖氨酸摄入量对体赖氨酸沉积量生成回归方程，将截距设为0时，计算方程斜率k值。

     试验二，选用45头初产母猪（妊娠39.4±2d，体重165.7±13.6kg），随机分为4组，分别提供日SID苏氨酸需要量（NRC 2012）的60、70、80、90%，妊娠早期、中期、末期SID苏氨酸需要量分别为6.46、6.05、9.75g/d。动物饲养管理、氮平衡试验、数据收集和计算、统计分析同试验一。

     试验结果表明，在妊娠早期和中期，日粮SID赖氨酸和苏氨酸对体蛋白沉积、赖氨酸沉积和 苏氨酸沉积没有显著影响。在妊娠后期，体蛋白沉积、赖氨酸沉积和苏氨酸沉积线性提高（P ＜0.001）。妊娠后期，SID赖氨酸和苏氨酸k值均为0.54。妊娠早期和中期体蛋白沉积无变化，这可能是因为赖氨酸和苏氨酸的过量摄入。最低日粮赖氨酸和苏氨酸供应下，妊娠早期它们的沉积效率分别为0.49和0.32；妊娠中期沉积效率分别为0.61和0.52。

     基于以上试验结果，SID赖氨酸和苏氨酸的沉积效率在整个妊娠期并不保持一致。

Two experiments were conducted to determine the efficiency of utilizing SID Lys and Thr for whole-body protein retention (kSIDLys and kSIDThr) in pregnant gilts. In Exp. 1, 45 gilts (158.0±8.0 kg at day 39.4±1 of gestation) in 2 groups were used in a 3-period nitrogen (N)-balance study. Gilts were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of predicted daily SID Lys requirement for protein retention (NRC, 2012) in each of early (day 41 to 52, 10.44 g/d), mid- (day 68 to 79, 9.60 g/d), and late gestation (day 96 to 107, 16.04 g/d). Diets contained 3,300 kcal ME/kg and 11.6% CP; given at a rate of 2.13 kg/d in early and mid-gestation and at 2.53 kg/d during late gestation. The 12-d balance period (7-d adaptation; 5-d urine and fecal collection) was based on total urine collection using urinary catheters and determination of fecal N digestibility using indigestible marker. The SID Lys required for whole-body protein retention was estimated using the NRC (2012) model and the predicted Lys content of each gestation pool. Lysine efficiency at each diet Lys level was calculated as the ratio of daily Lys retention and SID Lys intake. The linear and quadratic response in whole-body N and Lys retention and Lys efficiency for each balance period was determined. The kSIDLys was determined from the slope generated by regressing whole-body Lys retention vs. SID Lys intake, with y-intercept set to 0. In Exp. 2, 45 gilts (165.7±13.6 kg at day 39.1±2 of gestation) were assigned to 1 of 4 diets set to provide 60, 70, 80, and 90% of the predicted daily SID Thr requirement for protein retention in each of early (6.46 g/d), mid- (6.05 g/d), and late gestation (9.75 g/d). Animal management, N-balance procedure, data collection and calculation, and statistical analyses were patterned from Exp. 1. In early and mid-gestation, whole-body N retention, as well as Lys and Thr retention, was not affected by the dietary SID Lys and Thr. In late gestation, there was a linear increase (P < 0.001) in whole-body N, Lys and Thr retention. The kSIDLys and kSIDThr in late gestation were determined to be 0.54. The lack of response in whole-body protein retention in early and mid-gestation may in partly reflect excess Lys and Thr intake. Lysine and Thr efficiency calculated at the lowest dietary Lys and Thr was 0.49 and 0.32 in early gestation and 0.61 and 0.52 in mid-gestation, respectively. Based on the available evidence, kSIDLys and kSIDThr do not appear to be constant throughout gestation.（转自：猪营养国际论坛）