Association Of Carcass Quality Traits, Genetic And Management Factors On Scrotal Circumference Development In Yearling Angus Bulls

Abstract

The objective of this study was to estimate the association among various carcass traits, genetic and management factors on scrotal circumference development in yearling Angus bulls. Data obtained from Angus bulls (N=1374) were retrospectively evaluated. Pearson correlation coefficient analysis was performed to estimate the linear relationship between the variables. The mean ( SEM) scrotal circumference (SC), body weight, and carcass traits were different among age groups, locations, years and expected progeny difference (EPD) groups (P<0.05). For yearling bulls, positive correlations were observed between the following: body weight and SC (r=0.11; P=0.0001), age (d) and SC (r=0.22; P=0.0001), SC-EPD and adjusted yearling SC (r=0.50; P=0.0001), 240 d SC and yearling SC (r=0.42; P=0.0001), SC and adjusted yearling rump fat (r=0.07; P=0.008), SC and adjusted yearling rib fat (r=0.12; P=0.0001), SC and adjusted yearling rib eye area (r=0.13; P=0.0001), SC and adjusted yearling percent intramuscular fat (r=0.06; P=0.05). Bull average daily weight gain during the trial period was positively correlated with growth differences in SC during the same period (r=0.13; P=0.0001). The SC growth per day was higher for bulls completing the trial period at < 1 year of age compared to those > 1 yr, and higher SC EPD values were associated with more SC growth during the trial period. In summary, the current study shows significant but moderate to poor positive associations among yearling bull SC and various growth and carcass quality traits, so we conclude that the best method to increase SC in Angus bulls would be by independent bull selection based on the sire SC-EPD trait.