This study was conducted to evaluate the effect of recombinant bovine somatotropin (rbST) administration to dairy ewes in late lactation on milk yield, composition, clotting parameters, and plasmin/plasminogen system. Eighty multiparous lactating Comisana ewes (186±18 days in lactation) were randomly assigned to one of two treatments: control and rbST. Slow-release rbST (120 mg/ewe) was administered for two injection cycles of 21 days each. Recombinant bovine somatotropin treatment increased milk (589.7 vs. 483.7 g/d; p < 0.01), protein (35.5 vs. 31.4 g/d; p < 0.05) and lactose (27.3 vs. 23.1 g/d; p < 0.05) yields. The percentage of milk fat (8.2% vs. 8.9%; p < 0.01) and protein (6.0% vs. 6.2%; p < 0.05) decreased, while somatic cells count and pH were unaffected by rbST treatment. Administration of rbST decreased milk coagulation time (r) (12 vs. 13.1 min; p < 0.05), while firming rate (k20) and curd firmness (a30) were unaffected. Plasminogen activity of milk was lower in rbST-treated ewes (18.11 vs. 21.89 U/ml; p < 0.01).
|Titolo:||Response of dairy ewes in late lactation to recombinant bovine somatotropin|
|Data di pubblicazione:||1999|
|Appare nelle tipologie:||Articolo|