Temperature-humidity index influences incidence of diseases and pre-weaning growth performance in Djallonke lambs
Keywords:Temperature, humidity, diseases, climatic condition, average daily gain, sheep
The breed of sheep predominantly kept in the guinea savannah zone of Ghana is the Djallonke type, and there is no single report on the influence of the temperature-humidity index (THI) on health and growth performance of these animals under this environment, despite the threat posed by climate change. A study involving the birth records of 3824 Djallonke lambs was conducted to document the effects of THI on growth performance during the months of birth and weaning, and incidence of diseases. Average daily gain (ADG) during the month of birth was not influenced (P > 0.05) by THI. Lambs raised under higher THI (≥ 27.7) had lower ADG than those raised under lower THI (≤ 25.6) during the month of weaning. Bacterial, fungal and viral diseases were higher (P ≤ 0.05) at lower THI, while arthropod and helminthic diseases were higher (P ≤ 0.05) at higher THI. Correlations between THI and monthly incidence of bacterial, fungal and viral diseases were moderate to strong and negative. Conversely, positive correlations were found between THI and monthly incidence of arthropod and helminthic diseases. Diseases of the digestive system were higher (P ≤ 0.05) at higher THI, while respiratory and integumentary diseases were higher at lower THI. Higher THI impedes growth performance of Djallonke lambs prior to weaning, and increases the incidence of arthropod and helminthic diseases, while lower THI enhances the emergence of viral, fungal and bacterial infections.