Effect of Lactation and Ration on the Fat and Vitamin A Level of Sow's Milk

Abstract

Ten sows carried through gestation in dry lot and 10 sows carried through gestation on pasture were milked at the time of parturition, on the 3d day, at the end of the 1st week and each subsequent week until weaning after 8 weeks. Letdown of milk was induced by 1 ml. of Pitocin injd. intraven. the ear. No breed difference between Poland China and Chester White sows occurred in the fat content of the milk or vitamin A content of the fat. For dry-lot sows the mean values for first-day colostrum were 6.45% fat, 25.41 [mu]g. vitamin A/g. fat; for 3d-day colostrum 14.04% fat, 12.55 [mu]g. vitamin A/g. fat; for normal milk 7.45% fat, 5.69 [mu]g. vitamin A/g. fat. For pasture sows the mean values for first-day colostrum were 6.73% fat, 40.23 [mu]g. vitamin A/g. fat; for 3d-day colostrum 9.99% fat, 18.13 [mu]g. vi- tamin A/g. fat; for normal milk 6.12% fat, 10.93 [mu]g. vitamin A/g. fat. There was a gradual decline in fat content of the milk as lactation advanced. An increase in vitamin A content of the milk fat toward the end of lactation was evident in the pasture sows, but a reverse trend occurred in the dry-lot sows.