Detection of cobalt deficiency in lactating heifers and their calves

Abstract

SummaryResponses in live weight, milk production and calf growth to cobalt supplementation of groups of three and four pregnant heifers were measured to assess the value of serum vitamin B12 concentrations and the urinary concentrations of methylmalonic acid (MMA) and formiminoglutamic acid (FIGLU) for the detection of cobalt deficiency in cattle.The administration of cobalt bullets to pregnant heifers, grazing pastures containing between 0·03 and 0·05 mg/kg cobalt, had no effect on either their live-weight change or milk production, or on the birth weight of their calves. MMA and FIGLU concentrations in the urine of unsupplemented heifers were low for the majority of the experimental period, although the concentrations of vitamin B12 in their serum (< 100 pg/ml) were in the range usually considered indicative of cobalt deficiency.Calves from unsupplemented heifers had lower growth rates during the first 3 months of life and this was associated with intakes of 0·24–0·46 μg/day of vitamin B12 from milk, only 1–3% of those received by calves from supplemented heifers. Poor growth was associated with high urinary FIGLU concentrations, which increased from 500 to 2000 μmol/l between 1 and 3 months of age but decreased to less than 100 μmol/l between 3 and 4·5 months of age. Urinary FIGLU was a more reliable indicator of vitamin B12 deficiency in suckled calves than was urinary MMA, elevated levels of which were observed only at 3 months of age. The concentration of vitamin B12 in the serum of calves from unsupplemented heifers was consistently less than 100 pg/ml, but was not a reliable indicator of their functional vitamin B12 status, as judged by urinary concentrations of FIGLU and/or MMA.