Increasing the energy content of lactation diets fed to first-litter sows reduces weight loss and improves productivity over two parities

Abstract

In an experiment designed to evaluate the lactation and reproductive response to increasing energy in lactation, 288 pregnant nulliparous sows were allocated to diets formulated to contain: 13.0, 13.6, 14.2, 14.7 or 15.3 MJ digestible energy (DE)/kg of diet fed. Sows commenced their dietary regimen at 109.6 ± 0.1 days of gestation. Sows were fed 3 kg/day of their treatment diet before farrowing, then diets were offered ad libitum until weaning at 26.9 ± 0.1 days. Sows were fed a commercial diet postweaning until mating and throughout their subsequent gestation. There was no effect of dietary energy level on first-litter size born (10.5 ± 0.1 liveborn) or average piglet birthweight (1.44 ± 0.01 kg). Sow ad libitum feed intake during lactation was also unaffected by dietary energy level. There was no linear or quadratic response to dietary energy level on litter gain during lactation (1.79 ± 0.03 kg/day). Consequently sows lost weight during lactation in an inverse linear response to dietary energy level (P < 0.001) and sow weaning weight and backfat P2 increased with energy level (181 kg and 16.1 mm at 13.1 MJ DE/kg versus 191 kg and 17.2 mm at 15.3 MJ DE/kg, respectively, P < 0.05). The proportion of sows staying in the herd until their second litter and the cumulative litter size over two parities was maximised when sows were fed a lactation diet containing at least 14.2 MJ DE/kg (P < 0.05). Increasing the dietary energy content of lactation diets resulted in an improvement in sow productivity over their early parities, but did not increase lactation performance.