Quantifying the influence of heat stress on the conception rate of Ghana Sanga cows

Abstract

Heat stress as measured by temperature humidity index (THI) negatively impacts cow productivity, but its effect on cows in Ghana has been underexplored. The goal of this study was to investigate the effect of THI during the day of insemination on conception rate of Sanga cows. Artificial insemination records on Sanga cows were obtained from the Amrahia Dairy Farm of Ghana. Daily temperature and relative humidity records were obtained from the Ghana Meteorological Agency weather station in Tema, Ghana. A fixed effect model was fitted with conception rate as the dependent variable and parity of cow, year of insemination and THI on the day of insemination as independent variables. The study revealed a significant (P ≤ 0.05) effect of THI on conception rate of Sanga cows. The conception rate for cows inseminated on days when THI ranged from 79 to 82 was 82.7% while conception rates for cows inseminated on days when THI ranged from 83 to 85 and 86 to 88 were 76.4% and 54.7%, respectively. A unit increase in THI reduced conception rate significantly (P ≤ 0.05) by 12% in Sanga cows inseminated when the THI ranged from 79 to 82 but not in THI classes 83 to 85 and 86 to 88, indicating that 79 is the THI threshold at which conception rate in Sanga cows begins to decrease. Heat stress on the day of insemination had an adverse effect on the conception rate of Sanga cows. Heat abatement strategies are needed for improved reproductive performance of Sanga cows.