Abstract

Research has shown some dairy cows show temporary falls in plasma calcium concentration during the first six weeks of lactation. By monitoring plasma calcium concentrations in 58 dairy cows in 4 herds for 42 days postpartum it was found that 33% showed at least one episode of a fall in plasma calcium concentration to <1.9 mmol/l. The mean plasma calcium concentration of these cows during this period was 2.15 mmol/l compared to 2.60 mmol/l for those cows which maintained plasma calcium concentrations above 2.10 mmol/l for six weeks and 2.35 mmol/l for another group which maintained plasma calcium concentration above 1.9 mmol/l but not always above 2.1 mmol/l. These mean calcium concentrations differed significantly (P<0.001) among the three groups and between sampling days after calving. There was no significant association between herd and distribution of cows in each group and age of cow was not significantly correlated with plasma calcium concentration on days 7, 9, 19, 29 and 42 after calving or with the overall mean concentrations. Sub-clinical hypocalcaemia may commonly occur in early lactation and have significant effects on production and reproduction in dairy cows.

AV, Campbell

Proceedings of the New Zealand Society of Animal Production, Volume 50, , 211-214, 1990