The effects of probiotic Lactobacillus acidophilus and/or prebiotic mannan oligosaccharides on growth performance, nutrient utilization, blood metabolites, faecal bacteria, and economics of crossbred calves

BACKGROUND: The ban on antibiotics as growth promoters paved the way for probiotics and prebiotics as growth promoters in animal production. AIMS: The present study was conducted to evaluate the effect of probiotic Lactobacillus acidophilus and/or prebiotic Mannan oligosaccharides on growth performance, blood biochemical variables, and faecal bacterial count in crossbred calves. METHODS: Fifteen-day-old crossbred calves (n=24) were divided into four groups, each consisting of six calves, and subjected to different experimental diets. The control group (T(0)) received a basal diet without any additives. The T(1) and T(2) groups received the basal diet and the probiotic (L. acidophilus, 2 × 10(10) cfu/g) @ 1 g/calf per day and prebiotic (Mannan oligosaccharide) @ 4 g/calf per day, respectively. Calves of the T(3) group were offered a basal diet and synbiotic (L. acidophilus, 0.5 g + Mannan oligosaccharide, 2 g/calf per day). The feed additives were mixed in milk. RESULTS: The results of 90 days feeding trial showed that calves of the T(3) and T(1) groups had higher (P<0.05) body weight (BW) gain and dry matter digestibility than the control. Feeding the probiotic showed a positive effect (P<0.05) on body length at the first, second, and third months, compared to the control. The blood serum total protein and globulin concentrations in the T(1) group, on days 30 and 90, and T(3) group, on day 90, were higher (P<0.05) than those of the control. All the treatment groups (T(1), T(2), and T(3)) showed a reduction (P<0.05) in faecal coliform and E. coli count, compared to the control, on the 15th and 30th days of the study. Additionally, the T(2) group showed a significant coliform count reduction on days 45 and 60 of the study. CONCLUSION: The dietary addition of L. acidophilus, 2 × 10(10) cfu/g @ 1 g/calf per day and the combination of L. acidophilus, 0.5 g + Mannan oligosaccharide, 2 g/calf per day improved growth performance, serum biochemical values, and favourable gut microbiota.