September 4, 2019
Our industry continues having subpar reproduction in the nation's beef cattle, and one of the tools designed to fix that issue appears to have been partially castrated.
In the fall issue of BEEF Vet magazine, which goes to beef veterinarians and health consultants, we featured stories on changes in bull breeding soundness exams (BSEs) and problems with breeders not using valid BSEs.
According to our two veterinarian sources, this is a bigger problem than I would have imagined. One vet, in particular, mentioned that his offering of BSEs for bull producers has fallen on hard times because he actually counts sperm motility and mobility, checks the accessory sex glands, and performs a full examination as recommended in the BSE instructions from the founding organization, the Society for Theriogenology.
This veterinarian said too many of the breeders he was working for just want a “pass,” a claim of fertile or infertile by a glance through the microscope. He told of rectally palpating the accessory sex glands to help identify present or future problems and said one guy told him, “I don’t think he’s pregnant.” In a sense, it may be funny, but not really.
The two changes is the standards for a BSE are actually beneficial, as they have removed two abnormal sperm conditions from the list of "abnormal" conditions for the sperm cells. However, regardless of this new information, the truth is that we have a problem with subfertile bulls. The problem was set up over the last 40-50 years as we selected tall cattle. In simplest terms, puberty is delayed until long bone growth reaches a certain point. The longer the leg bones, the longer until puberty arrives. Further, we’ve stopped selecting for bulls that work in every way and instead select for bulls that have the right numbers. Therefore we have a huge amount of unsuited, forage-unthrifty, large-framed, hormonally imbalanced cattle.
As a result of all this, the long-term number of cows calving as a percentage of cows exposed falls somewhere in the mid to low 80-percentile range. I tend to believe it's probably around 82%, since I got that number several years ago from the southwest Standardized Performance Analysis (SPA) database kept for many years in Texas, Oklahoma and New Mexico. It included data from many medium and large ranches, so should have been representative.
I have also seen and published data from a large study of bulls using DNA testing for parentage in multi-sire pastures showing some bulls breed almost no cows, while others breed literally dozens.
Further, the Society for Theriogenology says one in five bulls, or about 20%, are "sub-fertile."
Cows are let slide too often for not calving or are fed expensively to get them bred. Bulls generally are not selected for masculinity or fleshing ability and tend only fall out of the herd when they get old or break down. The industry has become confused by all the focus on data, so the veterinarian and the breeding soundness exam was developed to help overcome these problems with infertility.
This suggests to me you should ask for a full BSE from your bull breeder. Even if you don’t fully understand it, the availability of the paperwork could be a litmus test for you.
If you want to learn more about the components of a bull breeding soundness exam, this online publication from Louisiana State University give many details: http://therio.vetmed.lsu.edu/bull.htm
This online fact sheet from Texas A&M gives a good overview: https://animalscience.tamu.edu/wp-content/uploads/sites/14/2012/04/beef-breeding-soundness-bulls.pdf
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