Reduction of lactational performance following bovine TNF-α administration to dairy cows

Abstract

Twelve lactating Holstein cows were injected subcutaneously with recombinant bovine Tumor Necrosis Factor-α (rbTNF, 2.5 μg/kg/day) or saline (3 ml/head/day) at 12.00 h daily for 7 d (d 0-6). Milk yield was reduced by rbTNF injection from d 1 to 8. The milk fat content was increased on d 1-7 by rbTNF treatment, but milk protein content in the rbTNF group was decreased on d 5 and 7 as compared with that of the control group. The somatotropin (ST) response to ST-releasing hormone (0.25 μg/kg) was smaller in the rbTNF group than in the control. These results support the possibility that TNF is responsible for the changes in hormone secretion, milk production and composition observed during coliform mastitis.