Impact of Water and Feed Consumption on Methane Production in South African Beef Cattle Under Intensive Production Systems

Enteric methane (CH₄) from beef cattle is a major greenhouse gas and an energy loss to the animal. Understanding how feed and water consumption patterns influence methane production across cattle of different body frame sizes is critical for developing sustainable beef production strategies. This study aimed to determine the impact of water and feed consumption on enteric methane production in South African beef cattle under intensive production systems. Fifteen beef cattle weaners of three different frame sizes (small = 5, medium = 5, and large = 5) 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 daily across different feeding phases (starter, grower, and finisher) and WFR were computed. Enteric methane was measured from experimental animals per frame size over five consecutive days per feeding phase using a portable Laser Methane Detector. General Linear Model of Statistical Analysis software (SAS) version 9.4 was used to analyze the data, and the means were separated using Tukey’s Honest Significant Difference (HSD) test. Pearson's correlation coefficient was used to determine the relationship amongst variables, whereas simple linear regression analysis was used to predict methane based on the intake traits. In the starter and grower phases, CH₄ did not differ by frame despite marked intake differences. Medium-frame cattle showed higher FI and WI but lower WFR, indicating efficient hydration relative to intake. In the finisher phase, medium-frame cattle produced more CH₄ (67.33 ppm) than small (34.56 ppm) and large (47.12 ppm). Across phases, CH₄ related weakly to WFR but showed a strong negative correlation with WI in the finisher phase (r=−0.688, p<0.05), suggesting enhanced rumen turnover may constrain methanogenesis. Intake behaviors, modulated by frame size and feeding phase, shape CH₄ dynamics in intensive systems. Managing FI and especially WI to optimize rumen flow offers a practical lever for mitigating CH₄ without compromising performance. Further validation across different diets and production systems is warranted, considering global call to align agricultural practices with Sustainable Development Goals (SDGs), particularly Goal 13 on Climate Action.