Effect of gestation metabolizable energy levels on sow productivity.

Three trials were conducted to study the effect of various levels of metabolizable energy (ME) on reproductive performance of crossbred gravid sows from breeding through gestation. One-hundred-one litters resulted from 124 sow matings during two summer and one winter trials over a 1 1/2-year period. Sows were fed 1.3 kg of a basal diet with additions of corn starch to provide 4,000, 5,000, 6,000 or 7,000 kcal of ME daily. A significant linear response due to treatment was shown for l l0 -day gestation weight gain with gains increasing with increasing ME intake. Sow 110-day gestation weight gain was negatively correlated with 21-day lactation gain (r = .46) , indicating the tendency for sows which gain more during gestation to gain less or lose more weight during lactation. There was a significant decrease in number of live pigs born as energy levels increased from 4,000 to 7,000 kcal of ME. Number of stillborn pigs was significantly correlated with l l0-day gestation gain of the sow (r = .76), indicating that increased gestation gain resulted in more stillbirths. Quadratic and cubic treatment effects for litter birth weight and a linear treatment effect for average pig weight were found. The heaviest litters were produced by sows fed 6,000 kcal, and the heaviest average pig weights were produced by sows receiving 6,000 or 7,000 kcal of ME. No differences in number of pigs weaned were observed among treatments. There was a significant quadratic effect on litter weaning weight and average pig weaning weight due to treatment. Sows fed 6,000 kcal ME daily