Effect of recombinant bovine somatotropin (rbST) and oxytocin on health indicators, reproductive performance and milk composition of Nili Ravi buffaloes (Bubalis bubalis) during spring and summer seasons

Abstract

The present study was designed to determine the effects of recombinant bovine somatotropin (rbST) and oxytocin, alone or in combination, on health biomarkers, reproductive performance and milk composition in lactating Nili Ravi buffaloes. A total of 250 buffaloes were randomly divided into three main groups. In group A, buffaloes were divided into three equal subgroups on the basis of their body condition scores (BCS), A1 (Low BCS), A2 (Medium BCS) and A3 (High BCS). In group B, buffaloes pertaining to milk production potential were divided into subgroups B1 (1-2.9 liters/milking), B2 (3-5.9 liters/milking) and B3 (6-12 liters/milking). In group C, buffaloes subjected to different treatments were divided into subgroups, C1 (control), C2 (oxytocin), C3 (rbST) and C4 (both rbST and oxytocin). The animals in all the subgroups received rbST (Boostin -250) at the dose rate of 35 mg on alternate days by s/c route in combination with oxytocin at the dose rate of 1 ml (10 I.U) I/m before each milking except in subgroup C1 (control), which was given no treatment, subgroup C2 which was given only oxytocin and subgroup C3 was given only rbST. Treatments were started on day 70 postpartum and continued till the end of lactation. Milk and blood samples were collected from animals of each subgroup during spring and summer seasons of study period (March 2013 to July 2014). The samples were stored at -20ᵒC till further processing. The results indicated that body condition score (BCS) of buffaloes treated with rbST and oxytocin significantly affected health biomarkers and milk composition. Serum AST activity and TOS were higher in rbST+ oxytocin treated buffaloes with high BCS, while TAC was higher in low BCS animals, compared to other groups. Milk fat contents were higher in high BCS buffaloes, while milk protein and lactose were higher in medium BCS animals. Higher frequency of brisket swelling and pregnancy rates were recorded in buffaloes with high BCS during spring and summer, respectively. In buffaloes treated with rbST+ oxytocin, milk production status had no effect on health biomarkers, reproductive performance and milk fat and protein contents. However, milk lactose and SNF contents were higher in buffaloes of high production group. Serum activities of liver enzymes and TOS were higher during summer, while TAS was high during spring. Similarly, milk protein and lactose contents were higher during spring than summer. Treatment of buffaloes with oxytocin decreased activities of ALT, AST, TOS and milk yield, while TAC was increased compared to controls. Buffaloes given rbST showed lower values of ALT, TOS and higher TAC than control group. Animals treated with rbST+ oxytocin had higher AST, TOS and lower ALT and TAC compared to controls. Milk fat, protein and lactose contents decreased due to rbST, oxytocin or rbST+ oxytocin treatment. Milk yield was increased after rbST treatment and decreased with oxytocin during spring. However, during summer, milk yield was increased after rbST+ oxytocin treatment, but decreased following treatment with either hormone. In conclusion, milk production was increased with recombinant bovine somatotropin and decreased with oxytocin during spring. Recombinant bovine somatotropin and oxytocin treatments showed adverse effects on general health of Nili-Ravi buffaloes.