Gregory Nicole L, Huber Lee-Anne
Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf168.
Fifty-five primiparous sows were recruited to evaluate the effect of increasing standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on primiparous sow maternal nitrogen retention, milk nitrogen output, and piglet growth performance during each week of lactation. Sows were assigned to one of five diets with equally spaced and increasing SID Lys-to-NE ratios between 2.85 and 5.51 g SID Lys/Mcal NE. The intermediate ratios were achieved by blending the two extreme diets in varying proportions using a feeding system with feed blending capabilities and were provided to sows immediately after farrowing and until weaning (day 24 ± 1). Nitrogen (N) balances were conducted between days 4 and 7 (week 1), 12 and 15 (week 2), and 20 and 23 (week 3) with total urine and fecal grab sampling occurring during each N balance period. Linear (LBL) and quadratic broken-line and polynomial quadratic models were used to determine the optimum dietary Lys-to-NE ratios for maternal N retention in each week of lactation. The Bayesian information criterion was used to assess best fit. Dietary feeding program did not influence sow average daily feed intake in lactation, piglet average daily gain and body weight (BW) at weaning, or milk N output during any nitrogen balance period. Sows fed increasing SID Lys-to-NE ratios lost less BW and backfat by the end of lactation (linear; P < 0.05). Sow N intake, N excretion, whole-body N retention (N intake - N excretion in urine and feces), and maternal N retention (whole-body N retention - milk N output) increased as dietary SID Lys-to NE ratio increased within each N balance period (linear; P < 0.05). The LBL model showed the optimal SID Lys-to-NE ratio for maternal N retention was out of the range of the dietary treatments for week one, but maternal N retention was optimized at 4.74 and 4.85 g SID Lys/Mcal NE in weeks two and three, respectively. Therefore, a dynamic SID Lys-to-NE ratio during each week of lactation could be implemented to enhance maternal N retention of primiparous sows.
招募了55头初产母猪，以评估提高标准化回肠可消化（SID）赖氨酸与净能（NE）比值对初产母猪在泌乳各周的母体氮保留、乳氮输出和仔猪生长性能的影响。母猪被分配到五种日粮中的一种，其SID赖氨酸与NE比值在2.85至5.51克SID赖氨酸/兆卡NE之间，且等间距增加。中间比值通过使用具有饲料混合能力的饲喂系统将两种极端日粮按不同比例混合来实现，并在分娩后立即提供给母猪直至断奶（第24±1天）。在第4至7天（第1周）、第12至15天（第2周）和第20至23天（第3周）进行氮（N）平衡试验，在每个氮平衡期采集总尿液和粪便随机样本。使用线性（LBL）、二次折线和多项式二次模型来确定泌乳各周母体氮保留的最佳日粮赖氨酸与NE比值。采用贝叶斯信息准则来评估最佳拟合度。日粮饲喂方案对泌乳期母猪平均日采食量、断奶时仔猪平均日增重和体重（BW）或任何氮平衡期的乳氮输出均无影响。饲喂SID赖氨酸与NE比值增加的日粮的母猪在泌乳期末体重和背膘损失较少（线性；P<0.05）。在每个氮平衡期内，随着日粮SID赖氨酸与NE比值增加，母猪氮摄入量、氮排泄量、全身氮保留量（氮摄入量 - 尿液和粪便中的氮排泄量）和母体氮保留量（全身氮保留量 - 乳氮输出量）均增加（线性；P<0.05）。LBL模型显示，第1周母体氮保留的最佳SID赖氨酸与NE比值超出日粮处理范围，但第2周和第3周母体氮保留分别在4.74和4.85克SID赖氨酸/兆卡NE时达到最佳。因此，在泌乳各周实施动态SID赖氨酸与NE比值可提高初产母猪的母体氮保留。
