Evaluation of feed grains with dried skim milk and added carbohydrate sources on weanling pig performance

Two experiments were conducted to evaluate the effects of 1) two grain mixtures and 2) various carbohydrate sources and levels fed to weanling pigs during the initial 2 wk postweaning. A total of 720 crossbred pigs were weaned at 23 +/- 2 d of age at an average BW of 5.8 kg. In Exp. 1, a 2 X 3 factorial experiment in a randomized complete block design was conducted in 12 replicates. Treatment diets formulated to 1.40% lysine were fed for a 14-d period. These diets contained dried skim milk (DSM) at a 45% level and an oat groat-soybean meal (OG-SBM-DSM) or a corn-soybean meal (C-SBM-DSM) mixture. In addition, the diets contained one of three carbohydrate sources (cornstarch, dextrose, lactose) at a 12% level. From 15 to 35 d postweaning, all groups were fed a 1.15% lysine corn-soybean meal (C-SBM) diet. The results demonstrated that during the period from 0 to 14 d weight gains were similar when either grain source was provided, but gain:feed ratio was superior and serum urea N was lower when the OG-SBM-DSM diet was fed. The addition of lactose or dextrose to either grain mixture resulted in greater weight gains (P < .05) than when cornstarch was the carbohydrate source. The second experiment was a randomized complete block design conducted in six replicates. The C-SBM-DSM diet of Exp. 1 served as the positive control diet. The other diets used corn gluten meal (CGM), SBM, and DSM with the three carbohydrate sources added at 22.5 or 35.5%. This resulted in total simple dietary carbohydrate levels of 22.5, 45, or 58%. The results demonstrated that when cornstarch was the added carbohydrate, weight gains and feed intake responses were lower during the initial 14 d postweaning, whereas supplemental lactose or dextrose resulted in improved weight gains (P < .01) to a total dietary level of 45%. These results suggest that dietary simple carbohydrate (lactose or dextrose) levels between 34.5 and 45% may be necessary during the initial 14-d postweaning period. During the subsequent period from d 15 to 35 when the C-SBM diet was fed, gain and feed performance responses were similar for all groups in both experiments and were not affected by their previous treatment diet.