Application of recombinant bovine somatotropin (rbST) in FTAI protocols and its effect on estrus detection and pregnancy rates in dairy cattle in a humid tropical

Abstract

The objective of the present study was to evaluate the effect of the application of recombinant bovine somatotropin (rbST) in different FTAI protocols to determine its influence on estrus detection and pregnancy rates in dairy cattle (Bos taurus) mantained under humid tropical conditions in order to apply a differentiated FTAI protocol that optimises fertility in this environment. Different fixed-time artificial insemination (FTAI) protocols were applied by including rbST in three groups of Brown Swiss breed cows: T1 (Control, no rbST), T2 (rbST application on Day-7, at P4 implant removal) and T3 (rbST application on Day-9, 48 h after P4 implant removal). Estrus detection rates were significantly higher when compared T2 (100 %) with T1/T3 (62.5 % and 75 %, respectively), being a 37.5% higher when compared to T1 and a 25% higher when compared to T3 (p<0.05). With regard to pregnancy rate, statistically significant differences were observed among T2 (62.5 %) and T1/T3 (50 %) treatments, being a 12.5% higher in T2 (p<0.05). In conclusion, the application of rbST in different FTAI protocols had a positive influence on estrus detection and pregnancy rates which were significantly higher when applying rbST on Day-7 (at P4 implant removal), being possible to develop efficient estrus synchronization and FTAI protocols and optimize fertility in dairy cattle (Bos taurus) in humid tropical environments

Keywords

• rbST
• TAI
• Fertility
• condition tropical
• bovine