Influence of water stress on feed intake, growth performance and nutritional status of Nguni goats.

Abstract

The broad objective of the study was to determine the influence of water stress (water deprivation, water restriction and water salinity) on feed intake, growth performance and the nutritional status of Nguni does. A cross-sectional survey was conducted to 135 farmers that keep goats from Jozini municipality of uMkhanyakude district in South Africa. Data collected included household demographics, goat production constraints, watering and feeding systems practised, including data regarding whether farmers milk goats. Varying periods of water deprivation (0, 24 and 48 h) on water intake, feed intake, water to feed ratio, average daily gain and feed conversion ratio were determined. Varying levels of water restriction (1000, 1200, 1400, 1600, 1800 and 2000 mL) and water salinity (0, 5.5 and 11 g/L) on average daily feed intake (ADFI), water to feed ratio (WFR), average daily gain (ADG) and feed conversion ratio (FCR) of Nguni goats were determined. Varying periods of water deprivation (0, 24 and 48 h) on body condition scoring (BCS), body weight (BW), faecal egg counts (FEC), FAMACHA scores, glucose, creatine, urea and cholesterol of Nguni goats were also determined. Varying levels of water restriction (1000, 1200, 1400, 1600, 1800 and 2000 mL) and water salinity (0, 5.5 and 11

g/L) on body condition scoring, body weight, faecal egg counts, FAMACHA, glucose, creatine, urea and cholesterol of Nguni goats were determined. Farmers were not aware of the value of goat milk, and they largely value meat from goats (P <0.01). Female farmers were likely to face water challenges (P <0.05). Farmers practising the scavenging production systems were likely to experience feed challenges. The ADWI was the same in goats deprived of water for 0 h and 24 h (P <0.05). The ADFI was largest for goats deprived of water for 48 h (P <0.01). The ADG and FCR declined as the level of water deprivation was increased (P <0.01). Water deprivation period was negatively correlated with ADFI, WFR, ADG and FCR. The ADFI peaked at 1600 mL of water restriction for goats subjected to 0 and 5.5 g/L of water salinity (P <0.01). The ADG peaked at 1400 and 1600 mL of water restriction across all water salinity levels (P <0.05). Body condition scoring and body weight were largest for goats deprived of water for 0 h (P <0.01). The FEC increased as water deprivation period was increased. Correlations between water deprivation period with FAMACHA, BCS and BW were negative. Correlations with FEC and creatine kinase were, however, positive. The BCS and FAMACHA scores to the peak, and later declined beyond 80 % of water restriction for goats subjected to 0 and 5.5 g/L of water salinity (P <0.05). The BW increased as the level of water restriction decreased across all water salinity levels tested (P <0.01). The FEC decreased as the level of water restriction decreased for goats subjected to 0 and 5.5 level of water salinity (P <0.05). Creatine concentration decreased as the level of water restriction was decreased across all water salinity levels tested (P <0.05). There was a linear relationship between urea and water restriction for goats subjected to 0 g/L of water salinity (P <0.05). It was concluded that goats are constrained by lack of input resources such as water. On the other hand, water deprivation period can be set to 24 hours for Nguni goats since increased periods of water deprivation compromise goat productivity. Also, water restriction and water salinity for Nguni goats can be set to 1600 mL and 5.5 g/L, respectively since further increments do not seem to improve goat productivity. Key words: water resources, water stress, productivity, Nguni goats.