The aim of present study was to determine the optimal concentration of dietary protein required in transition diets for multiparous sows that enhance the farrowing process, colostrum production, and subsequent lactation performance. Forty-eight multiparous sows were allotted to one of six dietary treatments according to bodyweight (290 ± 3 kg) and parity (3.8 ± 0.2) from d 108 of gestation until 24 h after the onset of farrowing. The diets were isoenergetic and contained increasing concentrations of dietary protein (expressed as standardized ileal digestible [SID] Lys) and were supplied at a daily feed supply of 3.8 kg. On d 108 of gestation and d 2, 7, 14, 21 and 28 of lactation, body weight and back fat depth were recorded, and blood was sampled on d 108 of gestation, at the onset of farrowing and d 3, 10, 17 and 24 of lactation from the sows for analysis of plasma metabolites. On d 115 of gestation, urine and feces were collected for nitrogen (N) balance. The number of liveborn and stillborn piglets and time of birth were recorded and blood from every fourth piglet was sampled at birth for blood gas analysis. Piglets were weighed individually from birth until weaning, to estimate the colostrum and milk yield of the sows. Colostrum and milk samples were collected, and their compositions were determined. On d 3 and 28 of lactation, sows were injected with deuterium oxide to estimate body composition. The N utilization was maximized when the concentration of SID Lys in the transition diet was 6.06 g/kg (P < 0.01). When urinary concentrations of urea were expressed relative to creatinine, the relative concentration of urea remained low until a dietary concentration of 6.08 g SID Lys/kg, above which the relative concentration of urea increased (P < 0.01). Stillbirth rate increased linearly with increasing SID Lys concentration in the transition diet (P < 0.001), thus the concentration of SID Lys should be kept as low as possible without impairing sow performance excessively. A carry-over effect on milk yield was observed, showing that a dietary SID Lys concentration of 5.79 g/kg during transition optimized milk production at an average yield of 13.5 kg/d (P = 0.04). Increasing loss of body fat in lactation was observed with increasing SID Lys concentration in the transition diet (P = 0.03). In conclusion, the transition diet of multiparous sows should contain 5.79 g SID Lys/kg when fed 3.8 kg/d (13.0 MJ ME/kg), for a total SID Lys intake of 22 g/d.

中文翻译：

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围产期母猪日粮中的最佳蛋白质浓度

本研究的目的是确定多产母猪过渡日粮中所需日粮蛋白质的最佳浓度，以增强分娩过程、初乳产量和随后的泌乳性能。从妊娠第 108 天到产仔开始后 24 小时，根据体重 (290 ± 3 kg) 和胎次 (3.8 ± 0.2)，将 48 头经产母猪分配到六种日粮处理中的一种。日粮是等能量的，并且含有浓度不断增加的日粮蛋白质（以标准化回肠可消化[SID]赖氨酸表示），并且每日饲料供应量为3.8千克。妊娠第108天和哺乳期第2、7、14、21和28天记录体重和背膘深度，并在妊娠第108天、产仔开始时和第3、10、17天采集血液样本24 头母猪哺乳期的血浆代谢物分析。在妊娠第 115 天，收集尿液和粪便以进行氮 (N) 平衡。记录活产和死产仔猪的数量以及出生时间，并在出生时对每四头仔猪进行血液采样以进行血气分析。从出生到断奶，对仔猪进行单独称重，以估计母猪的初乳和产奶量。收集初乳和牛奶样品，并测定它们的成分。在哺乳期的第 3 天和第 28 天，给母猪注射氧化氘以估计身体成分。当过渡日粮中SID Lys浓度为6.06 g/kg时，氮利用率达到最大（P＜0.01）。当尿液尿素浓度相对于肌酐表示时，尿素的相对浓度保持较低，直到膳食浓度为6.08g SID Lys/kg，高于该浓度尿素的相对浓度增加(P＜0.01)。死产率随着过渡日粮中 SID Lys 浓度的增加呈线性增加（P < 0.001），因此 SID Lys 浓度应保持尽可能低，但不会过度损害母猪生产性能。观察到对产奶量的延续效应，表明过渡期间日粮 SID Lys 浓度为 5.79 g/kg，可优化产奶量，平均产量为 13.5 kg/d（P = 0.04）。随着过渡饮食中 SID Lys 浓度的增加，观察到哺乳期体脂损失增加（P = 0.03）。总之，当饲喂量为 3.8 kg/d (13.0 MJ ME/kg) 时，经产母猪的过渡日粮应含有 5.79 g SID Lys/kg，SID Lys 总摄入量为 22 g/d。