Live Animal, Carcass and End Point

Correlation of Docility and Exit Velocity with Economically Relevant Traits

Presented by Janice M. Rumph, Michigan State University Extension, North Region, Lake City, and Michigan State University Animal Science Department, East Lansing; and Cathy Ernst, Janice Siegford, Courtney Daigle, Dan Buskirk and Dave Hawkins, all of Michigan State University Animal Science Department, East Lansing

Abstract:
Two different groups of cattle, weaned calves entering the feedlot and bulls enrolled in the Michigan Cattlemen’s Association/Michigan State University Bull Test, were evaluated as part of a preliminary project to correlate docility traits with economically relevant traits. Both groups were evaluated for docility using docility score [measured on the six-point scale used by the North American Limousin Foundation (NALF)] as well as exit velocity. For calves, docility score and exit velocity were measured at weaning, prior to transport to the feedlot (44 days postweaning) and after delivery to the feedlot later that same day.

All docility scores and exit velocities were positively and moderately correlated with each other. Of all time periods, pre-transport showed the most significant correlations to growth traits with correlations of -0.17, 0.20 and 0.25 to birth weight, pre-transport weight and hip height, respectively, indicating that calves with higher birth weights that are slower growing tend to have higher exit velocities when leaving the chute.

For the bulls, measurements were taken for docility score and exit velocity every 28 days during the test when bulls were weighed, docility score in the sale ring and exit velocity upon leaving the ring. Although there was little correlation between scrotal circumference and exit velocity during the normal weigh dates (0.05), there was a moderate correlation with exit velocity on sale day (-0.21), indicating that bulls with larger scrotal circumference were slower moving out of the sale ring, and bulls with smaller scrotal circumferences were more eager to leave the ring.

Ultrasound carcass traits also showed a significant correlation with sale day docility measures, but not docility during the test. Docility score was moderately correlated with marbling and fat with correlations of 0.43 and 0.34, respectively. It appears that the added stress of the sale environment allowed docility measures to be a better indicator than the same measures within the facility and procedures that bulls have become accustomed. Interestingly, all correlations involving sale day docility were nonsignificant when compared with price, indicating that a bull’s behavior in the ring did not affect his market value.

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