Water-Use Efficiency for Post-Weaning Growth Performance of South African Beef Cattle Under Intensive Production Systems

This study determined the water-use efficiency for post-weaning growth performance of beef cattle of different frame sizes under intensive production systems. A total of 33 beef cattle weaners of three different frame sizes (small, medium, and large) were randomly allocated individually to metabolic pens. Feed and water were provided ad libitum. The water intake (WI), feed intake (FI), and weight were measured across different feeding phases (starter, grower, and finisher). Water consumption (WC) average daily gain (ADG), weight gain (WG), water intake efficiency (WIE), water footprint per animal (WFP/AU), and WFP/kg were computed. General Linear Model of Statical Analysis software (SAS) version 9.4 was used to analyse the data, and the means were separated using Fisher's LSD test. The results showed that large-frame beef cattle had significantly higher (<i>p</i> < 0.05) WT_f. (412.73 ± 27.27 kg) and WI (3394.09 ± 156.3 L), but also the largest WFP/AU (4407 ± 197.22 L). The medium-frame cattle achieved the highest ADG (1.48 ± 0.14 kg/day) and a moderate WIE (20.15 ± 2.18 L/kg gain), indicating an optimal trade-off between productivity and water use. The small-frame beef cattle exhibited the best WCE (0.051 ± 0.005 kg/L) and the lowest WFP/AU (3822 ± 197.22 L), highlighting superior water-use adaptability. Pearson's correlation revealed that WCE was positively associated with ADG (r = 0.499; <i>p</i> < 0.05) and negatively with WIE (r = -0.987; <i>p</i> < 0.05). These findings suggest that medium-frame beef cattle provided a balanced compromise between growth performance and resource efficiency, making them more suitable for sustainable production in water-limited environments.