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Dietary effect of lactose on growth performance of nursery pigs on a liquid feeding system
A total of 216 weaned pigs (mean initial BW 6.4 ± 1.4 kg and average age 18 d) were used in a 42-d trial to evaluate effects of lactose on growth performance of nursery pigs. Piglets were grouped into 3 categories (mean initial BW 7.7, 6.1, and 4.8 kg for heavy , middle, and light groups, respectively) and fed isocaloric diets containing 0, 10, or 15% of lactose provided by whey powder from d 1 to 14 (phase 1) postweaning and then common diets without lactose from d 15 to 42 (phase 2). The 3 diets in phase 1 had same levels of standardized ileal digestible lysine, methionine + cysteine, threonine, and tryptophan. Spray dried porcine plasma was not used in the diets but fish meal was included in both phases. Each dietary treatment had 8 pens with 9 (5 gilts and 4 barrows) pigs per pen. Pigs were fed by a liquid feeding system (Big Dutchman, Vechta, Germany) without fermentation of feed. Water to feed ratio was 3:1 for all treatments during the whole experimental period. ADFI was presented on 88% dry matter basis. Pen was the experimental unit and treatment, BW category and their interaction were included in the statistical model for statistical analysis of growth performance data. No interaction between lactose level and BW category was noticed (P > 0.10). In phase 1, a linear increase (P < 0.05) in ADG and gain to feed ratio and a tendency of quadratic change in ADFI (P < 0.10) were observed with increasing levels of lactose. However, there were no differences (P> 0.10) in ADG, ADFI and feed efficiency in phase 2 and the overall period. Collectively, our data indicate that inclusion of lactose in phase 1 may enhance growth performance of phase 1 piglets fed by the liquid feeding system but this advantage is not maintained after phase 1.
Keywords: lactose, nursery piglets, liquid feeding