Determination of the appropriate dietary digestible lysine-to-metabolizable energy ratio for HL-VCN sows during gestation
This study aimed to evaluate the effects of the dietary digestible lysine-to-metabolizable energy ratio (dLysTH/ME) during gestation on the reproductive performance of HL-VCN sows. HL-VCN is a pig line developed from Hương and Landrace genetic resources and subsequently stabilized over three generations. A completely randomized design was used, involving 45 HL-VCN sows randomly allocated to three treatments corresponding to diets with LysTH/ME ratios of 2.036, 2.143, and 2.250 g/Mcal ME, representing 95%, 100%, and 105%, respectively, of the reference level derived from TCVN 1547:1994. Each treatment comprised three replicates, with each replicate consisting of one group pen housing five sows and serving as the experimental unit. Variation in the LysTH/ME ratio within the investigated range did not affect total piglets born, piglets born alive, or birth weight (P>0.05). However, the LysTH/ME ratio affected weaning weight; piglets in the 2.250 g/Mcal ME treatment reached 6.13 kg/piglet, which was higher than the 5.75 kg/piglet recorded in the 2.036 g/Mcal ME treatment (P<0.05). Differences among treatments were also observed in sow body-weight changes, body-weight loss during lactation, the weaning-to-estrus interval, and feed-use efficiency. The treatment providing 2.143 g dLys/Mcal ME resulted in the lowest sow body-weight loss, the shortest weaning-to-estrus interval (P<0.001), and the lowest feed consumption per kilogram of weaned piglet weight (P=0.04). Under the conditions of this study, a digestible lysine-to-metabolizable energy ratio of 2.143 g/Mcal ME provided the most appropriate balance among reproductive performance, nursing performance, maintenance of sow body condition, and feed-use efficiency.
