Abstract

The aim of this study was to test the hypothesis that Rumensin capsules administered during late pregnancy would have equally beneficial effects in single- and twin-pregnant beef cows, on circulating levels of beta- hydroxy butyrate (BOH), magnesium (Mg) and glucose. Forty cows, half of which were twin pregnant, were treated with either a single Rumensin capsule from a mean of 66 d prior to calving, or remained as untreated controls. Plasma samples were taken on d66, 38, 23, 13 and 5 prior to calving. Rumensin lowered BOH concentration by the second sampling time (0.53 vs. 0.765 mmol/l, P<0.01) and maintained this concentration until calving. Rumensin was without effect on Mg or glucose concentrations. The effects of Rumensin were additive to those of pregnancy status (twin vs. single) for all three metabolites thus confirming our hypothesis. Rumensin may therefore be useful in the late pregnancy management of twin pregnant cows.

WH, McMillan, AP Oakley, and W Hewitt

Proceedings of the New Zealand Society of Animal Production, Volume 55, , 265-267, 1995