Oxidative stress biomarkers in West African Dwarf goats reared under intensive and semi-intensive production systems
This study explored the variation in physiological oxidative status of West African Dwarf (WAD) goats as the rainy season progressed in a humid climate in south-west Nigeria. A total of 24 growing WAD bucks, averaging 10.5 kg + 0.78 liveweight, were reared under intensive and semi-intensive management systems during the rainy season. Twelve (12) bucks were used for each management system. Animals raised intensively were fed Megathyrsus maximus hay ad libitum, while those reared semi-intensively were allowed to graze freely in a fenced paddock. Their diets were supplemented with a maize grain-based concentrate. Blood samples were collected at the onset of the experiment and fortnightly throughout the 16-week experimental period. Oxidative stress biomarkers in blood were measured and analysed separately for each rearing system using repeated measures analysis. Means of oxidative stress biomarkers measured at the beginning and end of the rainy season were compared using a T-test. Results showed that intensively managed goats had significantly higher levels of bilirubin and uric acid in the early season than in the late rainy season. In semi-intensively managed goats, bilirubin, uric acid, and glutathione (GSH) levels were significantly higher at the start compared with the end of the rainy season. It could be concluded that the antioxidant capacity of WAD goats was greater early in the rainy season compared with the late rainy season under both management systems. Thus, during the early raining season WAD goats tend to have higher antioxidant capacity and, consequently, better immune responses, while the opposite is true during the late rainy season.
Keywords: bucks, immune response, season