Dietary lactulose supplementation improves grower-finisher pig performance and indices of gastrointestinal tract function

Concerns regarding the use of antibiotics in the pig industry have increased the interest in possible alternatives to antibiotics including prebiotics such as non-digestible oligosaccharides (Branner et al. 2004). Lactulose (4-O-β-D-galactopyranosyl-D-fructose) is metabolised in the colon by the saccharolytic microbiota (Bird et al. 1990), and can influence the intestinal microbiota by stimulating the growth of Lactobacillus spp. in the gastrointestinal tract (GIT). Previous studies show that lactulose elicits a prebiotic effect (increased counts of Bifidobacteria and Lactobacillus) in pigs (Konstantinov et al. 2004). The hypothesis tested in this experiment was that lactulose supplementation in diets could improve grower-finisher pig performance and bacterial counts.

This study was conducted to evaluate the effects of lactulose on growth performance, diet component digestibility and faecal microbial shedding in grower-finisher pigs. A total of 80 (Landrace × Yorkshire × Duroc) pigs with a bodyweight (BW) of 20.8 ± 3.20 kg (mean ± SD) and aged 10 weeks was randomly allotted to four dietary treatments with four replicate pens per treatment and five pigs (three gilts and two barrows) per pen. Dietary treatments included: Control (CON), pigs fed a basal diet; L05, CON + 0.05% lactulose (L); L10, CON + 0.10% lactulose; and L15, CON + 0.15% lactulose. The experiment included two stages: grower (0 to 6 weeks) and finisher (6 to 18 weeks). All pigs were fed diets mixed with 0.2% chromium oxide to calculate the coefficient of total tract apparent digestibility (CTTAD) of DM, nitrogen (N) and gross energy (GE). At the end of experiment, faecal samples were collected directly by massaging the rectum of pigs randomly selected from each pen (one gilt and one barrow) from which a 1 g sub-sample was diluted with 9 mL of 10 g/L peptone broth to evaluate faecal microbiota (i.e. Lactobacillus, E. coli, C. perfringens, and Bifidobacteria). All data were subjected to statistical analysis via a randomised complete block design using GLM procedures (SAS^®; USA). Duncan’s multiple test was used to compare the means of the treatments.

Pigs fed L10 and L15 diets had greater average daily gain (ADG) throughout the overall period when compared with the CON diet (793, 801 vs 778 g, respectively, P < 0.05). Pigs fed L10 and L15 diets increased faecal Lactobacillus and reduced E. coli counts compared with CON pigs (P < 0.05, Table 1). The CTTAD of DM was greater for the L10 and L15 treatments than CON pigs (0.76 and 0.77 vs 0.72; 0.81 and 0.81 vs 0.76, P < 0.05, respectively) at weeks 12 and 18.

Table 1.  Effect of lactulose supplementation on faecal microbiota counts in growing-finishing pigs

Results from this study indicated that L10 and L15 supplementation improved performance in growing-finishing pigs. Cho and Kim (2014) suggested that the improved growth performance observed in response to dietary lactulose supplementation occurs through an increased nutrient digestibility and improved faecal microbiota. Lactulose cannot be hydrolysed by digestive enzymes but fermented to short chain fatty acids in the lower gut and reduces pH of the ileal environment, and promotes growth of beneficial types of bacteria. These include Bifidobacterium, Eubacterium, and Lactobacillus, as well assuppressed E. coli counts in the large bowel (Boguslawska-Tryk et al. 2012), which could be used to explain the increased Lactobacillus and decreased E. coli seen in this study.