Masters Theses

Date of Award

12-2023

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Kyle J. McLean

Committee Members

Phillip R. Myer, Justin Rhinehart, Troy N. Rowan

Abstract

In the production of breeding bulls, growth and development are impacted by many nutritional, genetic, and environmental factors. Meeting the requirements needed to reach sexual maturity is critical to maximize production efficiency. Water is an essential, yet understudied component of these physiological requirements. By identifying potential differences in water drinking behaviors, we may better understand interactions between water intake and developmental efficiency. We hypothesized that drinking behaviors during development would differ between bulls and that these behaviors would be correlated to growth and reproductive traits. Beef bulls (n=71), on performance test, were group housed by breed and body weight (BW). Bulls were fed a single ration with ad libitum access to water and grass hay. Drinking behavior was monitored over a 112-day period to calculate the average number of visits per day (VPD) and total time per day (TPD). Additionally, daily visits and average time per visit per day was calculated on a weekly (W) and monthly (M) basis. A breeding soundness exam was conducted for each bull on day 112 where sperm motility (%MOT), morphologically correct sperm (%MOR), head defect (HD), midpiece defects (MD), tail defects (TD), and scrotal circumference (SC) were quantified. Linear mixed-effect models were used to determine differences in water consumption behavior between individual bulls, as well as any relationships between these behaviors and measurements of growth and reproductive development. SmartScale ID was included as a random effect to account for pen separation and breed differences. Bull to bull differences were found (P < 0.03) for all categories of VPD and TPD. A significant relationship was observed between VPD and average daily gain (ADG; P = 0.02), TPD and ADG (P = 0.04), as well as a tendency for VPD and BCS (P = 0.08). Additionally, a significant relationship existed between SC and final body weight (P = 0.01). No water use traits were significantly associated with reproductive traits. These results indicate differences in drinking behavior between bulls with correlations to growth and development. This suggests potential for water intake behavior to serve as an indicator for overall productivity in the development of breeding bulls.

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