131 Pilot: Does Drinking Water Availability Affect Stocker Cattle Grazing Wheat Pasture?

Abstract

Abstract The objective was to determine if restricting drinking water affects animal performance and hematological responses in cattle grazing high-moisture-content, fresh wheat pasture. Angus-cross steers (n = 10, 411 kg ± 24.5 kg) were randomly assigned to either 100% or 50% of baseline (d -7 to 0) water intake. The design of this experiment was a completely randomized design with 5 replications, with steer as experimental unit. Steers were individually hand-watered 1X per d for the entire experiment (d -7 to 28). Body weight, packed-cell volume (PCV), plasma total solids (PTS), fecal DM (F_DM), eyeball recession score (ERS) and skin turgor score (STS) were recorded from each steer weekly. Forage mass and forage DM were calculated weekly by hand-clipping ten, randomly-located samples using a 0.96-m forage hoop. Data were analyzed using ANOVA methods in SAS v9.4, and pairwise comparisons of means were completed using Fisher’s LSD methods at the nominal 0.05 level of significance. Restricted steers gained less than unrestricted steers (P < 0.01, 1.04 vs. 1.35 kg / d, respectively). Fecal DM percentage did not differ (P = 0.26). There was no difference in PCV (P = 0.15) or PTS (P = 0.27); however PCV and PTS linearly decreased (P < 0.001) from d -7 to 28 for both treatment groups. Eyeball recession score and STS did not differ between treatment groups (P = 0.34). The mean forage mass and forage DM (d -7 to 28) were 2,229 kg per hectare and 24%, respectively. In conclusion, restricting water intake to cattle grazing wheat pasture resulted in lower ADG; however differences in hematological measures of dehydration were not observed in this study.