Bovine mammary involution following intramammary infusion on colchicine and endotoxin at drying off

Effects of intramammary infusion of colchicine, endotoxin, and colchicine in combination with endotoxin on mammary involution were studied on 25 dairy cows in late lactation. Both quarters of right udder halves were infused at or near drying off while left udder halves received no infusion. Samples of mammary secretion were obtained 1 day prior to drying off, at drying off, and .5, 1, 2, 3, and 7 days post drying off. Mammary secretion obtained during the early dry period from udder halves infused with colchicine or colchicine and endotoxin at or near drying off had elevated somatic cells, lactoferrin, serum albumin, immunoglobulin G, and pH as compared to left untreated udder halves. Citrate, molar ratio of citrate to lactoferrin, and the index of selective accumulation of immunoglobulin G were lower in infused than uninfused udder halves. Fluid volume removed from udders at 7 days involution was 40% less in udder halves infused with colchicine or colchicine and endotoxin as compared to uninfused udder halves. Intramammary infusion of colchicine and endotoxin at drying off accelerates bovine mammary involution.