Lack of production response in grazing dairy cows supplemented with long-acting injectable vitamin B12.

AIM To determine the concentrations of vitamin B₁₂ in serum, liver and milk that identify adequate vitamin B(12) status in grazing lactating cows, based on no change in milk production in response to supplementation with vitamin B₁₂. METHODS In October 2005, in early lactation, Friesian cows from one herd were injected S/C with 60 or 90 mg long-acting… (More)