Selection of a novel direct-fed microbial to enhance weight gain in intensively reared calves

A novel bacterial strain isolated in Australia, Propionibacterium jensenii 702 (PJ702), was examined for its potential as a direct-fed microbial to improve weight gain in calves. Holstein bull calves, 24, were randomly allocated into a Treatment or Control group and held under simulated commercial calf rearing conditions. Both groups were treated identically, with the exception that the Treatment calves were given between 1.1×108 and 1.2×109 cfu/(kg day) of PJ702. Faecal recovery of PJ702 from the Treatment calves from week 2 indicated successful gastrointestinal transit of the bacterium, and blood haematology and biochemistry indicated no adverse effects following PJ702 administration. There were improvements in weight gains with the Treatment group during both the pre-weaning (P=0.001) and the weaning period (P=0.04). Eighteen weeks after cessation of treatment, and removal to an extensive farming operation, Treatment calves remained heavier to the Control calves (P=0.03), with a final weight difference between the groups of 21.3 kg.