Milk yield and secretion composition following intramammary infusion of colchicine.

Twenty-five lactating dairy cows were in a split block design to investigate effects of intramammary colchicine infusion on milk yield and composition. Right udder halves of 15 cows were infused with colchicine while left udder halves received no infusion. Ten cows received no infusion in either right or left udder halves. At 24 h postintramammary colchicine infusion, milk yield decreased 38.5% in treated halves and 9.3% in control halves. Udder halves of uninfused cows had an 8.7% reduction. Milk from treated halves compared to untreated halves had elevated somatic cells, serum albumin, and pH. Citrate and the molar ratio of citrate to lactoferrin were lower. Lactoferrin and immunoglobulin G did not differ between infused and uninfused halves; however, they increased in treated halves postinfusion as compared to preinfusion. Serum albumin and citrate increased, and the index of selective accumulation of immunoglobulin G decreased in left halves. Control cows did not differ.