In mid-March, we ultra sounded the yearling bulls that have been on the gain/performance test here in the feedlot.
Ultra sounding an animal allows us to put a score of muscling by weight, which would be difficult by visual observation alone. Casey Worrell (certified by the Ultrasound Guidelines Council) came out & ultra sounded the bulls.
As he scanned each animal, we were able to see a cross section between the 12th & 13th rib on his screen. The results were then sent to us which included rump fat, rib fat, rib eye area, & percent intramuscular fat for each animal. With this information, we can compare each animal with a ratio of square inches of rib eye muscle per 100 pounds of animal.
As the bulls were in the chute, we also weighed them & measured hip height. Individual disposition notes were recorded as well.
A combination of weight & hip height determine a ‘frame score’. A frame score is used to estimate the growth pattern & potential mature size of an animal. Frame scores are moderately heritable & can be used to influence the selection process before breeding.
An ideal hill country cow that has a calf every year & is able to do that on solar energy that caliche hills convert into grass. That is not the same type of animal that is considered ideal in the tall grass prairies of Montana, Nebraska, or the Dakotas. This is where the frame score becomes important. A large frame size cow has a higher maintenance requirement than a smaller frame size cow.
The next day, we took the bulls to Gillespie Vet Center for their Breeding Soundness Exam (BSE). A BSE includes three evaluations: 1) structural soundness assessment, 2) reproductive system evaluation, & 3) semen quality appraisal.
The structural soundness assessment involves examining the overall condition of the animal, including flesh, feet, legs, eyes, & teeth.
The reproductive system evaluation includes examination of the scrotum, testicles, & penis, as well as a rectal palpation to determine any internal abnormalities. The circumference of each bull’s scrotum was measured. The circumference of a scrotum can estimate the amount of sperm producing tissue in a bull. There is a high correlation in scrotal circumference & sperm output. To be considered a good potential breeder, a yearling bull’s scrotal circumference must be greater than 30 cm, must have greater than 50% sperm mobility, & greater than 70% normal sperm. source: Society for Theriogenology
The final phase of a BSE consists of semen collection & an evaluation of the semen.
Having a BSE report on each bull tells our buyers that the bull they are purchasing is not sterile & is able to breed.
Each of these evaluations play a key role in selection of bulls. After reviewing all of the information about each bull, decisions were made as to which bulls to keep for our own breeding program & which ones to sell.