Document Type

Thesis - Open Access

Award Date

2021

Degree Name

Master of Science (MS)

Department

Animal Science

First Advisor

Cody Wright

Abstract

Two completely randomized design feedlot experiments were conducted over the course of a year. Both experiments were performed in order to determine the effects of weather, body weight (BW), and feed intake on total daily water intake (TDWI) and liquid daily water intake (LDWI) in beef steers. Experiment 1 utilized Angus weaned steers (n = 27; initial BW = 273 + 21.3 kg). Experiment 2 utilized yearling Bos taurus steers (n = 26; initial BW = 421 + 16.2 kg). Individual feed and water intake were collected using the Insentec (Insentec RIC, Hokofarm, Marknesse, Netherlands) automated feeding and water system. Water was supplied from the Brookings Municipal supply. Feed and water samples were obtained weekly. Feed samples were dried in order to determine the dry matter and the water contained within the feed. Water samples were weighed weekly in order to determine the amount of total dissolved solutes contained in the water. Individual weights were obtained every 28 days in order to estimate predicted daily BW in each individual steer. Weather was collected through the South Dakota Mesonet's Brookings location. Windchill, solar radiation (SRAD), and maximum relative humidity (RHMax) were obtained for Experiment 1. Maximum ambient temperature (TAMax), SRAD, and windspeed (WSPD) were obtained for Experiment 2. A linear repeated measures model with both random intercept and slope slope estimated for each animal were used to account for within subject correlations; BW and DMI included in the model as covariates. Effects of DMI, BW, SRAD, and windchill were positively associated with TDWI and LDWI in beef calves fed during the winter (P < 0.001); RHMax was negatively associated with TDWI and LDWI (P < 0.001). Additionally, effects of DMI, BW, SRAD, and TAMax were positively associated with TDWI and LDWI during the summer (P < 0.001); WSPD was negatively associated with TDWI and LDWI (P < 0.001). In Exp. 1 the R2 observed for the models for predicting TDWI and LDWI was 0.657 and 0.730 respectively. Furthermore, in Exp. 2 the R2 for the models predicting TDWI and LDWI was 0.686 and 0.670 respectively. When comparing previously developed models to the current study on a dataset independent from this study, this study provided the lowest average residual amongst studies (3.20 L/day) and the highest goodness of fit (R2 = 0.810). Based on the R2 observed in each model developed, DMI, BW, SRAD, windchill, RHMax is useful for predicting TDWI and LDWI in winter months in the Upper Midwest. Furthermore, DMI, BW, SRAD, TAMax, and WSPD are useful for predicting TDWI and LDWI in summer months in the Upper Midwest.

Library of Congress Subject Headings

Beef cattle -- Water requirements.
Beef cattle -- Climatic factors.
Beef cattle -- Feeding and feeds.
Beef cattle -- Weight.

Number of Pages

117

Publisher

South Dakota State University

Included in

Beef Science Commons

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