Assessment of the adaptation of Nguni goats to water stress.

Abstract

The recurring drought and limited rainfall patterns occasioned primarily by climate change in sub-Saharan African countries threaten sustainable animal agriculture. The irreversibility of this natural phenomenon calls for an intensive and urgent selection of adaptable breeds that can cope but with minimal compromise on production indices. A water scarcity simulation study was conducted to assess the adaptation potential of Nguni goats to regulated watering by evaluating their growth performance, tolerance to heat and water stress and blood indices during the dry summer months. Eighteen growing Nguni goats (average age: 1year; BW: 19.25±1.6kg) were assigned equally to three treatments: W0, without water restriction (WR); W70, WR of 70% ad libitum water intake (WI); and W50, WR of 50% ad libitum WI. The experimental trial lasted for 75 d following a 14-day acclimatisation to the housing condition. Data on growth performance, body thermal gradient, skin temperature (ST) and rectal temperatures, respiratory rate (RR), body condition scores (BCs), linear body indices and blood biochemical indices were taken. The results showed that the final BW was not affected (P>0.05) by the water restriction levels. The daily gain, DM intake and total BW gain were similar (P>0.05) in groups W70 and W50. Body thermal gradient and ST were not affected (P>0.05). The RR and BCs decreased (P<0.05) with increasing water restriction levels. The body and rump lengths and sternum height were similar (P>0.05) for groups W70 and W50. There is an haemocentration (W0<W70<W50; P<0.05) of sodium, Chloride, urea, creatinine, total protein, and cholesterol with water restriction levels. Generally, most physiological variables assayed were similar (P>0.05) in the water-stressed groups (W70 and W50). Overall, Nguni goats showed an adaptive capacity to tolerate limited water intake.