The effect of feeding salmon oil to sows throughout pregnancy on pre-weaning mortality of piglets

Salmon oil (16.5 kg /t), a source of long-chain polyunsaturated n-3 fatty a cids, was included in diets offered to multiparous sows during pregnancy an d lactation to measure responses in pre-weaning mortality and performance o f piglets in two studies. Thefirst study, carried out under commercial cond itions, included 196 sows which were offered salmon oil and control diets f rom immediately post service until weaning. The same diets were also offere d to 10 sows per treatment from day 58 of pregnancy in a controlled nutriti onal study which measured the effects of salmon oil on piglet tissue fatty acid composition. Offering salmon oil to the sow significantly increased ge station length and decreased individual piglet birth weight but had no effe ct on litter size at birth. Overall, salmon oil reduced pre-weaning mortali ty from 11(.)7% to 10(.)2% mainly by reducing the incidence of deaths from crushing by the sow. More detailed analysis of mortality using a general li near mixed model and 2294 piglet records, demonstrated that [lie incidence of pre-weaning mortality was significantly decreased with increasing indivi dual piglet birth weight and by inclusion of salmon oil in the diet; the in cidence of mortality increased with average piglet birth weight in a litter . Salmon oil inclusion had no effect on weight of litter weaned, sow lactat ion food intake or subsequent reproductive performance. In both studies, di etary salmon oil increased the proportions of long-chain n-3 polyunsaturate d fatty acids in colostrum to a similar extent. In the nutritional study, i nclusion of salmon oil reduced the proportions of 20 : 4 n-6 in piglet live r and brain at birth and increased the proportions of long-chain n-3 polyun saturated fatty acids. Therefore, despite reducing piglet birth weight, off ering sows salmon oil reduced pre-weaning mortality of piglets. The nutriti onal study showed that the amount and type of marine oil used may not have been optimal.