Effects of D Ietary Dried Whey and Corn Oil on Weanling Pig Performance, Fat Digestibility and Nitrogen Util Ization 1,2

Two experiments were conducted to evaluate the effects and interactions of dietary levels of corn oil (0 vs 6%) and dried whey (0 vs 25%) on performance of young pigs during a4-wk postweaning period. The first experiment, conducted in five replicates as a 2 • 2 factorial in a randomized block design, evaluated gain and feed intakes of 172 pigs weaned at 21 d of age. Pigs were bled at weekly intervals, and samples were assayed for serum triglyceride and urea concentrations. In a second experiment, 36 barrows in three replicates were used to evaluate the same treatments on apparent digestibility and absorption of fat and N retention during each week of a 4-wk postweaning period. The dietary inclusion of dried whey resulted in greater gains and feed intakes and reduced feed-to-gain ratios during each week of the postweaning period, with the largest relative improvement occurring during wk 1. Supplemental corn oil did not enhance pig gains the first 3 wk postweaning, but response improved by wk 4. Feed intakes were slightly (P < .10) lower when corn oil was provided. The inclusion of corn oil resulted in an improved feed-to-gain ratio (P < .OIL particularly evident during wk 3 and 4 postweaning. Neither gain nor feed utilization were improved by added corn oil during the initial 2-wk postweaning period regardless of dried whey addition. Apparent digestibilities of fat were unaffected at each weekly interval by dietary dried whey inclusion. Nitrogen retention was improved (P < .05) and serum urea concentrations were lower each week for pigs fed dried whey. Corn oil supplementation reduced N retention and increased serum urea concentration during the initial 2 wk postweaning, implying that it had a detrimental effect on amino acid utilization. (