Abstract：
To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.
摘要：
为了避免哺乳期间现代瘦母猪体内蛋白质的高动员，充足的膳食氨基酸（AA）供应和有效的AA利用至关重要。本研究评估了饲粮CP和体外蛋白消化动力学对母猪体况变化的影响，窝体重增加，牛奶成分，血液代谢产物,蛋白质利用效率和随后的繁殖性能。我们假设饮食蛋白质的较慢消化会提高AA的利用率和利用率。总的来说,110多胎母猪以2×2析因设计饲喂四种泌乳日粮之一，两种CP浓度：140g/kgvs180g/kg，和两种蛋白质消化动力学，以慢蛋白的百分比表示（30至240分钟之间的体外降解）：8vs16％的总蛋白。饲喂高CP日粮的母猪可减少母猪的体重减轻（Δ=7.6kg，P<0.01),估计身体脂肪损失(Δ=2.6kg，P=0.02),和估计的身体蛋白质损失(Δ=1.0kg，P=0.08),但只有在高比例的慢蛋白。在整个泌乳过程中，缓慢蛋白质的百分比增加了产仔数的增加（Δ=2.6kg，P=0.04），无论CP浓度如何，而较高的CP只会增加泌乳第3周的产仔增重（Δ=1.2kg，P=0.01）。分娩后第15天，从饲喂高CP饮食的母猪的子样本中采集系列血液样本。在这些母猪中，高百分比的慢蛋白导致在进食后150和180分钟血浆AA浓度较高（Δ=0.89，P=0.02，Δ=0.78，P=0.03，mmol/L，分别）和饲喂后90和120分钟的尿素增加较低（Δ=0.67，P=0.04，Δ=0.70，P=0.03，mmol/L，分别)。较高的饮食CP浓度增加了对环境的总氮损失(Δ=604g，P<0.01），蛋白质效率降低（Δ=14.8％，P<0.01)。在接下来的分娩中，较高百分比的慢蛋白增加了随后的活产产仔数（Δ=0.7，P<0.05）。总之,饲喂高日粮CP浓度的母猪，当日粮蛋白质消化率较慢时，可以减轻哺乳期母体的体重减轻，但降低了蛋白质的效率。较慢的蛋白质消化改善了窝体重增加，可能通过减少AA氧化和提高血浆AA的可用性，因此，提高蛋白质效率。
