Yang H, Pettigrew J E, Johnston L J, Shurson G C, Wheaton J E, White M E, Koketsu Y, Sower A F, Rathmacher J A
Department of Animal Science, University of Minnesota, St. Paul, USA.
J Anim Sci. 2000 Apr;78(4):1001-9. doi: 10.2527/2000.7841001x.
Effects of three dietary lysine (protein) concentrations during lactation on metabolic state, protein metabolism, reproductive hormones, and performance were investigated in 36 primiparous sows. Sows were assigned randomly to one of three diets containing .4% (low lysine, LL), 1.0% (medium lysine, ML), or 1.6% (high lysine, HL) total lysine from intact protein sources. All diets contained 2.1 Mcal NE/kg and exceeded the recommended requirements for all other nutrients. Actual lysine intakes over an 18-d lactation were 16, 36, and 56 g/d for sows fed LL, ML, and HL, respectively. Fractional breakdown rate of muscle was determined on d 4 and 15 of lactation by using a three-compartment kinetic model of 3-methylhistidine metabolism. Increasing lysine intake during lactation did not affect fractional breakdown rate of muscle on d 4 of lactation but decreased it on d 15 (P < .05). Sows fed LL had a reduced number of LH pulses on d 12 and 18 (P < .05) and reduced serum estradiol (E2) concentration on d 18 of lactation compared with sows fed ML and HL treatments. However, LH pulses and E2 concentrations were similar between ML and HL treatments (P > .35). Increasing lysine intake increased serum urea nitrogen (SUN) and postprandial insulin concentrations (P < .05) during lactation but had no effect on plasma glucose concentrations (P > .20). Sows fed HL had greater serum IGF-I on d 6 and 18 than sows fed ML (P < .05). Number of LH peaks was correlated with serum insulin concentration 25 min after feeding on d 6 and 18 (r = .31 to .41; P < .1) and pre- (r = .33 to .46) and postprandial (r = .30 to .58) SUN concentrations (P < .05) during different stages of lactation. Results indicate that, compared with medium lysine intake, low lysine intake increased muscle protein degradation and decreased concentrations of insulin, SUN, and estradiol and LH pulsatility. In contrast, high lysine (protein) intake increased SUN, insulin, and IGF-I, but did not increase secretion of estradiol and LH compared with medium lysine intake. Furthermore, nutritional impacts on reproduction may be mediated in part through associated effects on circulating insulin concentration.
研究了36头初产母猪在泌乳期三种日粮赖氨酸（蛋白质）浓度对代谢状态、蛋白质代谢、生殖激素和生产性能的影响。母猪被随机分配到三种日粮之一，日粮分别含有来自完整蛋白质来源的0.4%（低赖氨酸，LL）、1.0%（中赖氨酸，ML）或1.6%（高赖氨酸，HL）的总赖氨酸。所有日粮的净能均为2.1Mcal/kg，且其他所有营养素均超过推荐需求量。在18天的泌乳期内，采食LL、ML和HL日粮的母猪实际赖氨酸摄入量分别为16、36和56g/d。通过使用3-甲基组氨酸代谢的三室动力学模型，在泌乳期的第4天和第15天测定肌肉的分解率。泌乳期增加赖氨酸摄入量对泌乳期第4天的肌肉分解率没有影响，但在第15天降低了肌肉分解率（P<0.05）。与采食ML和HL日粮的母猪相比，采食LL日粮的母猪在第12天和第18天促黄体生成素（LH）脉冲次数减少（P<0.05），泌乳期第18天血清雌二醇（E2）浓度降低。然而，ML和HL处理之间的LH脉冲次数和E2浓度相似（P>0.35）。泌乳期增加赖氨酸摄入量可提高血清尿素氮（SUN）和餐后胰岛素浓度（P<0.05），但对血糖浓度没有影响（P>0.20）。与采食ML日粮的母猪相比，采食HL日粮的母猪在第6天和第18天血清胰岛素样生长因子-I（IGF-I）水平更高（P<0.05）。泌乳期不同阶段，LH峰值次数与采食后25分钟的血清胰岛素浓度相关（r=0.31至0.41；P<0.1），与采食前（r=0.33至0.46）和采食后（r=0.30至0.58）的SUN浓度相关（P<0.05）。结果表明，与中等赖氨酸摄入量相比，低赖氨酸摄入量增加了肌肉蛋白质降解，降低了胰岛素、SUN和雌二醇浓度以及LH脉冲频率。相反，与中等赖氨酸摄入量相比，高赖氨酸（蛋白质）摄入量增加了SUN、胰岛素和IGF-I，但没有增加雌二醇和LH的分泌。此外，营养对繁殖的影响可能部分通过对循环胰岛素浓度的相关作用来介导。
