Evaluation of Lactulose on Growth Performance, Nutrient Digestibility, Hematological Characteristics, Targeted E. coli Colony, Fecal Score, Moisture and Noxious Gas Emissions in Weaning Pigs

Abstract Text: Lactulose (LAC; a synthetic disaccharide) is widely used in human medicine for dietetic purposes (laxation, reduced ammonia absorption, increased counts of bifidobacteria and lactobacilli as well as reduced counts of clostrids, Salmonella or E. coli in gastrointestinal contents). A total of 210 weaning pigs [(Yorkshire × Duroc) × Landrace, BW = 5.77 ± 1.22 kg] were used to evaluate the effects of LAC. Pigs were assigned to 1 of 3 dietary treatments (14 pens/treatment, 5 pigs/pen) by BW and sex (2 barrows and 3 gilts). Treatments were corn soybean meal based diets supplemented with 0, 0.1 or 0.2% LAC. The white blood cells, lymphocyte counts and haptoglobin concentration in the whole blood were determined using an automatic blood analyzer (ADVIA 120, Bayer, NY, USA) and fecal Lactobacillus and E. coli shedding were measured by using MacConkey agar plates and lactobacilli medium III agar plates. During d 1 to 14, pigs fed LAC0.1 and LAC0.2 had greater (P<0.05) ADFI and ADG than those fed CON diet. The ADG (kg/d) was significantly improved in LAC0.1 diet compared to CON (0.674 vs. 0.649; P=0.024) from d 15 to 42. Pig fed with LAC0.1 (0.821) and LAC0.2 (0.812) showed higher feed efficiency that was followed by CON (0.780) during the last 28 d (P<0.05). During the entire experimental period, 0.1% and 0.2% LAC supplementation improved ADG (kg/d) and feed efficiency compared to CON (0.562, 0.814 and 0.558, 0.810 vs. 0.538, 0.779; P=0.013). In this study, nitrogen and DM digestibility was improved in LAC0.2 than CON diet (P<0.05) at 2 weeks. Likewise, at 6 weeks, pig fed with LAC0.1 and LAC0.2 had higher revelatory nitrogen and energy digestibility than CON diet (P<0.05). At d 42, LAC0.1 and LAC0.2 supplemental revealed higher fecal lactobacillus and lower E. coli count (log₁₀cfu/g) compared to CON (7.41, 7.15 and 5.35, 5.49 vs. 6.83, 5.62; P<0.05). Ammonia gas emissions was reduced in LAC0.1 and LAC0.2 diet over CON (P<0.05) at d 5 and 7. Moreover, at d 7, hydrogen sulfide production was reduced in LAC0.2 than CON (2.79 vs. 2.98 ppm; P=0.025). In conclusion, results demonstrated that supplementation of 0.1 or 0.2% LAC can amend growth performance, nutrient digestibility and fecal lactobacillus count but reduce fecal E. coli, ammonia and hydrogen sulfide gas emissions in weaning pigs.

Keywords: fecal microbiota, lactulose, weaning pig