Effect of an injectable microencapsulated Vitamin B12 on serum and liver Vitamin B12 concentrations in calves.
OBJECTIVE
To evaluate the efficacy of a long-acting injectable microencapsulated formulation of Vitamin B12 in dairy calves.


METHODS
Fifty calves, average liveweight 110kg, were randomly allocated to 5 groups of 10 animals and injected subcutaneously in the anterior neck with 0.12, 0.18, 0.24 and 0.3 mg Vitamin B12/kg liveweight using a formulation of microencapsulated Vitamin B12 in a lactide: glycolide copolymer. The untreated calves were injected with the same vehicle, without Vitamin B12. Subsequent changes in serum and liver Vitamin B12 concentrations were followed for 244 days.


RESULTS
The microencapsulated Vitamin B12 significantly increased, then maintained serum and liver Vitamin B12 concentrations higher than those of untreated controls for at least 110 days.


CONCLUSIONS
Injection of the microencapsulated Vitamin B12 at dose rates of 0.12 to 0.24 mg/kg liveweight will increase and maintain the Vitamin B12 status of calves for at least 110 days.
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AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand.
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