Vitamin B-12 supplementation en milk production on farms with 'chronic wasting' cows

From early 1999 onwards, cattle health problems accompanied by chronic wast ing of unknown aetiology were reported on a number of dairy farms. An assoc iation between these health problems and the compulsory use of gE-negative marker vaccines against bovine herpesvirus 1 was presumed by farmers. On on e dairy farm an increased milk production of 50% was reported within a few days after parenteral vitamin B-12 treatment. Therefore, the current study was designed to determine the effect of parenteral vitamin B-12 treatment o n the milk production of diary herds with wasting cattle. A randomized blind trial was performed in five problem herds and two contro l herds. On each farm five lactating cows were injected intramuscularly wit h 20 mg vitamin B-12 and paired with five untreated lactating cows. The mil k production of treated and untreated animals was measured for 19 days foll owing treatment and compared to pre-treatment production. No effect of vitamin B-12 treatment on milk production was established on e ither problem farms or control farms. Neither was a difference detected in the response to vitamin B-12 treatment between problem herds and control he rds. In a second experiment, parenteral vitamin B-12 treatment was applied in th ree problem herds by local veterinary practitioners. The results of this ex periment were in line with the results of the first experiment.