Growth of young cattle grazing high-moisture winter forages in a temperate environment was not affected by access to drinking water

Context. Early sown, annual ryegrass pastures and winter crops provide a high-quality feed for livestock and also have a high water content during autumn and early winter compared with typical temperate pastures.Aim. We hypothesised that beef cattle grazing annual ryegrass or forage oats would not need additional access to drinking water to maintain their intake and growth. Methods. In Experiment 1, 48 weaned, castrated male Hereford calves with liveweight 154 kg (+/- 6.7 kg; s.d.) grazed Italian ryegrass at a daily allowance of 4.5 kg dry matter (DM)/100 kg liveweight in two treatments including with or without access to drinking water. In Experiment 2, 60 Hereford steers with liveweight 382 kg (+/- 20.6 kg; s.d.) were offered a daily allowance of 5 kg DM/100 kg liveweight of forage oats in a 2 x 2 factorial design either with or without access to drinking water and with or without sorghum grain silage supplemented at I% of liveweight. The experiments were analysed as a completely randomised design, with individual pasture plots as the experimental unit. Key results. Daily growth rates of calves in the two treatments were similar (P > 0.05); however, calves with access to drinking water consumed 60% more water than did the calves without drinking water (P < 0.001). Access to drinking water had no effect (P > 0.05) on the daily growth rate of steers (P > 0.05); however, the daily growth rate of supplemented steers was 9% higher than that of the unsupplemented steers (P < 0.05). Total water intake was affected by access to drinking water (P < 0.005) but not access to supplementation (P > 0.05). Conclusions. Both calves and steers derived no production benefits by having access to drinking water when grazing actively growing annual ryegrass pasture or forage oats. Nevertheless, livestock should be monitored closely so that appropriate interventions can be made if there are changes in the pasture availability or weather.