Effects of dietary lysine levels on production performance, milk composition and plasma metabolites of the high-producing lactating sows

Abstract

Background Modern genotype sows require better nutrition because of larger body size and higher reproductive performance. Especially primiparous sows not only meet the needs of lactation, but also meet the needs of their own growth and development. The aim of the study was to evaluate the effect of dietary lysine over two consecutive lactations on lactation and subsequent reproductive performance in primiparous sows. Results A total of 160 primiparous Yorkshire sows were randomly allotted to one of four experimental lactation diets. Lactation diets were formulated to contain 0.84, 0.94, 1.04, and 1.14% SID Lys and balanced in Met, Thr, Trp and Val. There were no dietary effects on sows body weight and backfat change and feed intake of sows during lactation. However, WEI (P = 0.07) tended to be a quadratic effect by increasing dietary Lys level. Compared with the primiparous, sows had greater body weight (P < 0.01) and backfat thickness (P < 0.01) of sows at farrowing and at weaning, and weight loss (P = 0.01) during the second lactation period. Higher Lys level during lactation increased survival rate of piglets (P = 0.03), weight of piglets (P = 0.04), and weight gain of piglets at weaning (P = 0.05). Dietary Lys level did not affect colostrum compositions. However, fat (P = 0.04), protein (P = 0.03), solid not fat (P = 0.03), total solids content (P = 0.04), and moisture (P = 0.04) in milk increased linearly with increasing dietary levels of Lys. Likewise, PUN level was increased (P = 0.04). There were significant linear increases in plasma Lys (P = 0.02), Met (P = 0.05), and Val (P = 0.04) levels as dietary Lys level increased at weaning. Furthermore, there were significant linear increases in milk Asp, Glu, His, Ile, Leu, Lys, Met, Phe, Pro, Ser, Thr, Trp and Val levels as dietary lysine level increased (P < 0.05) at 21 d of lactation. Conclusions These results indicated that primiparous sows need higher dietary lysine levels than multiparous sow. Moreover, impacts of dietary amino acids on reproductive performance could be mediated through milk compositions change and increasing amino acid concentration.