Abstract #T270

# T270
Lactation performance of dairy cows milked 3 times per day and supplemented with two different formulations of bovine somatotropin.
Jozivaldo P. G. Morais*1, Andressa P. da S. Cruz1, Natalia S. Minami1, Luiz P. Veronese1, Tiago A. Del Valle1, Simone D. Sartorio1, 1Universidade Federal de São Carlos, UFSCAR, Araras, SP, Brazil.

The aim of this randomized field study was to evaluate the lactation performance of dairy cows supplemented with 2 different 500-mg bovine somatotropin (bST) formulations. Sixty Holstein cows were allocated to a control, 90 Holstein cows to a somatotropin fast release formulation (FR-bST, Boostin-S, LG Life Science), and 90 Holstein cows to a somatotropin slow release formulation (SR-bST, Lactotropin, Elanco Animal Health). Treatments (TRT) were delivered every 14 d starting at 57–70 d post calving until the end of lactation, or 17 injections. Before TRT assignment, animals were paired by milk yield, lactation number, and randomly assigned to one of the 3 TRT. Evaluated parameters were milk production, milk protein, milk fat, milk SCC, and BCS. Somatotropin treatment increased milk yield (P < 0.001). SR-bST treated cows, yielded 1.6 kg/day more milk than FR-bST treated cows (P = 0.008). Somatotropin increased milk protein % (P = 0.002), decreased BCS (P < 0.001), and had no effect on milk fat % (P = 0.120) and SCC (P = 0.964). Results are shown in Table 1. Table 1. Production variables of cows milked 3 times per day without bST and with 2 different bST formulations1
Item TreatmentSEMP-value42
No bstFR-bstSR-bstC1C2
Pre-TRT period
 Milk, kg/d40.0440.3839.960.4640.8800.635
 Fat, %3.363.173.280.0630.3490.469
 Protein, %2.682.732.690.0140.4480.216
 SCC, ×103/mL38.7439.9940.922.4590.3500.885
 BCS2.942.942.950.0160.8510.975
TRT period
 Milk, kg/d34.6338.0339.600.131<0.0010.008
 Fat, %3.183.063.100.0010.1200.576
 Protein, %3.013.113.070.0010.0020.086
 SCC, ×103/mL242.6181.1166.811.500.9640.865
 BCS3.042.952.930.003<0.0010.263
1FR-bST = Boostin-S, LG Life Science; SR-bST = Lactotropin, Elanco Animal Health. Starting on d 63 bovine somatotropin was administered at 14-d intervals to cows on the groups to receive bst. 2C1 = control vs. bST; C2 = FR-bST vs. SR-bST.

Key Words: milk composition, milk yield, recombinant bST