Effects of Dietary Lactose Levels and Supplementation of Probiotics on Growth Performance in Weanling Pigs

A 2 × 2 factorial arrangement was used to investigate the interactions between the lactose levels (100 g/kg versus 200 g/kg) and a probiotic (0 and 0.5 g/kg) on weanling piglets performance and nutrients digestibility. Two hundred and forty weaned piglets (24 days old, 7.05 kg live weight) were blocked on the basis of live weight and were assigned to one of four dietary treatments with 6 replicates (n = 10) for 28 days. The main effects of growth performance, nutrient digestibility, intestinal microbiota and morphology, fecal noxious gas emission and their interaction were determined by the GLM procedure. There was no interaction between lactose levels and probiotic supplementation on ADG, ADFI, F/G and coefficient of total tract apparent digestibility (CTTAD) of dry matter (DM), gross energy (GE) and crude protein (CP). Piglets offered probiotic had an improved ADG and ADFI. However, high lactose supplementation had no significant effect on ADG, ADFI, and FCR. Piglets offered diets containing 200 g lactose/kg had a significantly higher CTTAD for DM and GE compared with the 100 g lactose/kg in phase 1. Moreover, the CTTAD of DM was higher in both high lactose and probiotic supplemented diets (P<0.05). The supplementation of 200 g lactose/kg and probiotic did not affect the CTTAD of GE and CP in phase 2. The number of E. coli in ileum and cecum were decreased in probiotic-supplemented treatments (P<0.01). The ileal colonization of Salmonella spp. was decreased either in probiotic-supplemented (P<0.05) or high lactose level (P<0.05) treatments in phase 1. There were no effects of lactose levels and dietary probiotic on all morphological parameters. Fecal total organic carbon (P<0.01) and ammonium (P<0.05) emission were lower in piglets offered high lactose level or probiotic-supplemented diets. In conclusion, dietary probiotic improved growth performance and DM digestibility. There was no response of high lactose supplementation on growth performance, however, both lactose and probiotic increased the digestibility of DM and decreased the emission of total organic carbon and ammonium.