Effects of dietary lactose levels during different starter phases on the performance of weaning pigs

Two experiments were conducted to evaluate dietary lactose levels during different starter phases on growth performance, nutrient digestibility and fecal microbial populations. In experiment (Exp.) 1, a total of 192 weaning pigs (Landrace × Yorkshire; 21 ± 2 days of age; 6.94 ± 0.97 kg) were used and randomly allotted according to a 2 × 2 factorial arrangement to test the effects of dietary lactose levels and different starter feeding programs. Two different three phase starter feeding programs comprising of phase I (15 or 25% lactose), phase II (10% lactose) and phase III (0% lactose) diets were employed. Under feeding program 1, the phase I, II, III diets were fed during days (d) 0–7, d 7–21, and d 21–35 and under feeding program 2, the phase I, II, III diets were fed during d 0–14, d 14–21, and d 21–35, respectively. In Exp. 2, a total of 192 weaning pigs (Landrace × Yorkshire; 28 ± 3 d of age; 9.57 ± 0.79 kg) were used and assigned by a 2 × 2 factorial design similar to Exp. 1 and the same phase I, II and III diets were used. Under feeding program 1, the phase I, II, III diets were fed during d 0–7, d 7–14, and d 14–35; whereas, under feeding program 2, the phase I, II, III diets were fed during d 0–7, d 7–21 and d 21–35, respectively. In both the experiments, high lactose diets improved performance and nutrient digestibility and increased microbial populations of Lactobacillus spp. Additionally in Exp. 1, high lactose diets reduced fecal coliform population when compared with low lactose diets. These results demonstrated that maximum performance could be obtained through including 25% lactose during the initial 14 d post-weaning to pigs weaned at 21 d of age and during the 7 d post-weaning to pigs weaned at 28 d of age, respectively.