“Loss of protein mass in lactation and having suboptimal body reserves of lipid after weaning the first litter are primary causes. Gilts have lower lactation feed intakes than sows and this can be aggravated by high ambient temperatures in summer. Prolific gilts can have similar litter sizes to sows, but if daily nutrient intake is suboptimal, then mobilisation of body tissue can occur to meet the milk yield demands of the suckling piglets,” explains Dr Brian Hardy.
Dr Hardy is founder of NutriVision (Australia) Pty Ltd., an eco-friendly nutritional consulting business, and is a graduate of the University of Nottingham, England with a B.S. in agriculture, M.S. in animal science, and Ph.D. in swine nutrition.
He points to trials in Australia that clearly indicate that gilts respond to higher daily intakes of energy and lysine. “As genotypes become leaner and of higher prolificacy, the daily intake of energy and lysine will need to increase to prevent excessive mobilisation of body tissue that adversely affects subsequent performance and can result in early culling from the herd. In DE trials, gilt body weight loss was reduced with increasing DE level. When the DE was over 14.2MJ/kg, P2 back fat loss was reduced and more gilts were rebred within seven days of weaning and more were retained in the herd. There was no effect on subsequent litter size,” he notes.
In the lysine study, gilts with 12 or seven suckling pigs were fed diets with either 0.58g available lysine per MJ DE or 0. 90g available lysine per MJ DE for a 21-day lactation. Feed intake was about 5.6kg/day. Gilts with fewer pigs suckled or fed higher lysine levels had higher total born in the second parity. Piglets weaned from a litter size of seven had 850g heavier weaning weights.
Dr Hardy says the goal should be to achieve a high weaning weight at 28 days with minimal loss of body tissue. Meeting a lactating gilt body weight of 150kg, suckling 10 piglets and targeting a litter weaning weight of 85kg (8.5kg/pig) will need 10kg milk production per day. This needs a daily nutrient intake of 90 MJ and available lysine of 64g per day to minimise loss of body tissue.
“Know your gilt daily lactation feed intake and design the diet according to the target litter weaning weight and to minimise the loss of gilt body condition. Sows need to have more than three litters to recover the cost of the replacement gilt and feeding up to third litter,” notes Dr Hardy.
In the lysine study, gilts with 12 or seven suckling pigs were fed diets with either 0.58g available lysine per MJ DE or 0. 90g available lysine per MJ DE for a 21-day lactation. Feed intake was about 5.6kg/day. Gilts with fewer pigs suckled or fed higher lysine levels had higher total born in the second parity. Piglets weaned from a litter size of seven had 850g heavier weaning weights.