Drinking water intake (DWI) for feedlot cattle was assessed by meta-analysis using 35 studies, up to 131 experiments. A wide range of countries, breeds, sex, stages in the feedlot, and environmental conditions were represented. Studies were observational while others evaluated interventions including water quality and shade. Mean drinking water intake was 31.2 L/d (SD = 4.31), mean temperature 23.1°C (SD = 24.10), and temperature humidity index (THI) 69.1 (SD = 9.62). The average maximum daily temperature was 35.5 °C; however, greater temperatures were reported over shorter times. Two models predicted water intake 1) with temperature and body weight independently predicting DWI when average daily temperature was >12 °C with root mean square error (RMSE) 2.40 L/d. 2) THI and dry matter intake independently predicted DWI with RMSE 2.83 L/d. Estimates of DWI from the temperature and body weight model are much lower, that is, by 16.7 L/d (SD = 7.70) than NRC (2016). This concurs with well conducted individual studies that have strong internal validity but are less generalizable than models from this study. Results from seven studies and 23 experiments confirmed that increased sulfur content in water or feed (mg SO₄/L) reduces DWI. Five studies and six experiments showed that shade reduced DWI by 3.4 L/d. We provide robust estimates of changes in DWI for feedlot cattle with increases in environmental temperature, THI, bodyweight, and feed intake.

Read the full article in the Journal of Animal Science.