Reproductive performance of sows injected with vitamin A

The effect of vitamin A (450,000 IU, retinol palmitate) injected at weaning (T2) or mating (T3) on the reproductive performance of 1030 multiparous sows was studied in comparison to sow injected with a oil vehicle (T1). The number of piglets born alive at the subsequent parturition was 10.74+/-14, 10.67+/-14 and 10.32+/-14, for sows injected at weaning, mating or control group, respectively. Differences among vitamin A treatments (T2 + T3) versus control group (T1) were observed, through the contrast analysis, for the amount of piglets born alive, total born and litter weight. There were no differences among treatments for the amount of stillborn. The increase on the amount of piglets born alive was attributed to the reduction on the frequency of litters with small amount of piglets. This fact might be related to a possible retinol effect upon endogenous progesterone levels of the sow.