Performance of Weaned Pigs Fed Progressive Increments of Whey Extract Powder

Whey extract powder (WEP) from Agri Processing Services, LLC (Carmel, IN) was evaluated as a supplement for weaned pigs at the University of Wisconsin-Platteville’s Swine Center (Platteville, WI). The WEP had the following analysis: 10.2% CP, 20.0% crude fat, 11.3% Na, and 17.5% Cl. Eighty-eight pigs (initial BW 6.4 ± 1.5 kg) were blocked by weight and sorted into 8 pens. Each pen consisted of 5 barrows and 6 gilts. Blocked pens were randomly assigned to receive either the control or experimental treatment for the entire trial. Within a treatment group, 4 different diets were sequentially fed in 1-wk phases. For each phase, control diets were formulated to meet digestible Lysine:NE requirements for the average pig on-test. Experimental diets were formulated to be equivalent to the control diet while including progressive increments of WEP. The inclusion rate of WEP for the experimental group began at 2.5% for the first week and progressively increased to 5.0, 7.5, and 10.0% for the second, third, and fourth week, respectively. Pig weight and feed disappearance were recorded weekly. Data were subjected to ANOVA using JMP 13.0.0 (SAS Inst. Inc., Carey, NC). The final model included the fixed effects of weight block and dietary treatment. A pen of pigs was the experimental unit and differences were declared significant at P ≤ 0.05. Treatment means with a pooled SEM are reported on an individual pig basis. There were no performance differences (P ≥ 0.26) resulting from dietary treatment. Over the 4-wk trial, the control group had an ADG, ADFI, and G:F of 192 ± 4 g/d, 664 ± 18 g/d, and 0.29 ± 0.1, respectively. Over the 4-wk trial the treatment group had an ADG, ADFI, and G:F of 189 ± 5 g/d, 638 ± 18 g/d, and 0.30 ± 0.1, respectively. Although not statistically significant, ADFI of pigs fed experimental diets increased at a slower rate compared to pigs fed control diets. Pigs grew at the same rate regardless of dietary treatment, suggesting that the NE value of diets containing WEP might have been higher than estimated. Other factors such as Na and Cl concentration may limit the practical inclusion rate of WEP in pig diets. A study examining the impact of feeding a constant rate of WEP would further clarify the impact of this feedstuff on pig performance.