Effect of bovine somatotropine treatment on the chemical composition, rheological properties and curd yield in Manchega ewes milk

Ithaca, New York

Congreso; 90th American Dairy Science Association and Northeast ADSA/ASASMeeting; 1995

Cornell University - ADSA

The objective of the experiment was tu evaluate the effect of Bovine Somatotropin (BST) treatment in milk compositio, rheological properties and curd yield in Manchega ewes. Sixty three lactating dairy ewes were injected with release BST (sometribove). Ewes recived 0, 80, 160 mg of BST/14 day from wk 11 to 23 of lactation. Milk samples were taken from the morning milking at wk 14, 18, 22 postpartum. Administration of BST increased milk yield (49.2% y 53.5%) and lactose content respect to control group. Average fatty acid composition of milk fat was not influenced, except C12, C14 and C18:2 acids, which decresed, C18 and C18:1 acids which increased in relative concentrations due to BST treatment. Percentge of total protein (5.96, 5.41m 5.30)m true protein (5.68, 5.13, 5.02), and casein (4.51, 3.97, 3.89) were lower in milk from BST treated ewes. Casein as a percentage of true protein was lower (79.36, 77.46, 77.45) and the Sometribove treatment had no effect on percentages of whey protein and non-protein nitrogen. The effect of BST on protein content was releated to the maintenance of a high milk production level throughout the lactation respect to the control group. Rennet clooting time (43.4, 36.3, 35.7) and rate of firming ( 47.7,40.9, 40.9) were lower with BST treatmente while medium firmness and curd yield were not changed. The results of the study indicate minimal impact of BST in short-chain fatty acids characteristic of ewes milk, although there was slight decrease in protein and casein it did not effect curd yield