Effects of an unintended high dose of monensin on milk production and milk fat in a dairy herd
Keywords:bovine, monensin, overdose, milk production, adverse effects, case reports, cows, dairy cattle, dairy cows, lactation, milk fat, milk fat percentage, milk yield
Lactating dairy cows were accidentally fed monensin at a dose of 32.7 g per ton (36 ppm) of feed for three weeks. This resulted from a mixing error when monensin was added to the mineral premix, as well as an error in the amount of mineral fed to the lactating cows. A decrease in dry matter intake was noticed during the first three days following the mixing error. Bulk-tank milk fat percentage decreased by 0.6, but daily milk production increased by 6.9 lb (3.1 kg)/cow/day during this period, and for an additional two weeks. A residual effect on milk production and fat percentage was observed for three weeks after monensin intake returned to the prescribed dosage of 14.5 g per ton (16 ppm). This residual effect was more pronounced during the first week following resumption of the prescribed intake of monensin.