Evaluating two sources of dried whey and the effects of replacing the corn and dried whey component with corn gluten meal and lactose in the diets of weanling swine

Three experiments were conducted to evaluate the efficacy of replacing corn and dried whey with corn gluten meal (CGM) and lactose, and to evaluate two sources of edible-grade dried whey that elicited different postweaning pig growth performances. In Exp. 1, two corn-soybean meal (C-SBM) diets without or with 20% dried whey (C-SBM-DW) were formulated to contain 1.15% lysine. A third diet replaced the corn and dried whey component with CGM and lactose. The experiment used 108 crossbred pigs weaned at 23 +/- 2 d of age weighing 6.25 kg BW and was conducted in six replicates as a randomized complete block design. Pig weight gains when the C-SBM-DW diet was fed were poor in one trial, whereas a second trial resulted in improved (P < .01) performance responses to the inclusion of dried whey. The CGM-SBM-lactose diet resulted in pig gains that equaled the performance responses of the C-SBM-DW diet of Trial 2. A second experiment was subsequently designed to evaluate the effects of adding lactose or lactalbumin to the CGM-SBM-DW diets using the two dried whey sources that had been identified as good or poor quality in Exp. 1. Diets included dried whey at a 25% level and were formulated to a low lysine level (.95%) to assess the nutritional efficacy of the dried whey sources. The experiment was conducted for a 21-d postweaning period, used a total of 240 pigs weaned at 23 +/- 2 d of age initially weighing 6.6 kg BW and was conducted in six replicates in a randomized complete block design. Resulting pig weight gains demonstrated that during the 0- to 7-d postweaning period, dietary carbohydrate was the limiting nutritional factor when the pigs were fed either dried whey source, whereas from d 8 to 21 the amino acids from lactalbumin became the limiting nutritional component. Chemical composition of the two whey sources demonstrated that the poor-quality dried whey had a light brown color and was lower in both total and available lysine contents than the good-quality dried whey source. A third experiment evaluated the efficacy of increasing the dietary level of lactose in a CGM-SBM diet. A CGM-SBM diet with 47% cornstarch was compared with a C-SBM diet. The cornstarch component of the CGM-SBM diet was replaced with 50 or 100% lactose in two additional treatment groups. A total of 144 crossbred pigs weaned at 23 +/- 2 d of age initially weighing 6.0 kg BW were used in six replicates in a randomized complete block design. The results demonstrated similar pig gains and feed performance responses when the C-SBM or the CGM-SBM with added cornstarch was fed, but gains and feed intakes increased linearly (P < .01) as lactose increased from 0 to 47% for both the 0- to 14-d and 15- to 35-d postweaning period. The results of these experiments demonstrated that CGM and lactose could effectively replace dried whey in pig starter diets and that dietary lactose levels from 32 to 47% improved pig gains throughout a 35-d postweaning period.