Effects of β-Mannanase and Bacteriophage Supplementation on Health and Growth Performance of Holstein Calves.

The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. Thirty-six pre-weaning male Holstein calves were randomly allocated to one of four dietary treatments with a 2 × 2 factorial arrangement: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and 0.1% β-mannanase supplementation in a starter on a dry matter basis. The experiment lasted from 2 weeks before weaning to 8 weeks after weaning. Twenty-two calves survived to the end of the experiment. No interaction was observed between the two different feed additives. The bacteriophage supplementation tended to increase the odds ratio of survival ( = 0.09). The number of in feces significantly decreased by bacteriophage supplementation one week after weaning. β-mannanase supplementation increased the concentrate intake ( < 0.01) and tended to increase the final BW ( = 0.08). Analysis of repeated measures indicated β-mannanase supplementation increased weekly body weight gain ( = 0.018). We conclude that bacteriophage supplementation may have a positive effect on calf survival rate, while β-mannanase supplementation may increase the growth rate and starter intake by calves just before and after weaning.