Changes in bovine mammary-secretion composition during early involution following intramammary infusion of recombinant bovine cytokines.

This study was designed to determine whether intramammary infusion of recombinant bovine interleukin-1 beta or interleukin-2 had any adverse influence on bovine mammary function during the early non-lactating period. Mammary glands of eight Jersey cows were infused with either 10 micrograms of interleukin-1 beta or 1.0 mg of interleukin-2 following abrupt cessation of milking. Mammary secretions from each gland were collected from cows frequently during early involution and evaluated for changes in secretion composition. Percentage of milk fat and solids-not-fat during the experimental period was variable for all treatments. Percentage of protein increased throughout the study for all treatments, but mammary glands treated with interleukin-1 beta had higher protein percentages. All interleukin-treated mammary glands had lower concentrations of lactose than controls. Mammary secretions from interleukin-1 beta treated glands had higher concentrations of lactoferrin at 7 and 14 days of involution. Similarly, mammary secretions from interleukin-2 treated glands had higher concentrations of serum albumin on day 3 of involution and throughout the remainder of the study. Concentration of citrate and the citrate: lactoferrin molar ratio generally decreased throughout the study for all treatment groups. Concentration of alpha-lactalbumin in mammary secretions decreased throughout the study and was not different between treatment groups. Though significant changes in mammary secretion composition due to the presence of cytokines were observed in this study, resulting in an apparent acceleration of involution, there was no indication that these changes adversely affected normal bovine mammary function during the early non-lactating period.