You've seen the plethora of dairy articles about estrous synchronization, timed breeding, genomic testing, embryo transfer, and other neat things that can help you manage reproduction and genetic progress in your dairy herd. There's a good chance you're even using some of those strategies, but it's possible you've also still found it helpful to use a herd bull or two for getting some of your heifers or cows bred. You are not alone. There are still a lot of dairy herds with bulls roaming around (and hopefully working) in select pens. Other herd owners choose not to use herd bulls because of the risks involved, but it’s a decision you have the right to make.
If you’re using herd bulls, what factors go into choosing a bull to use in your herd? Is he a result of convenience, or have you thought through the reasons he may or may not be the right one?
Let’s start with health issues. If you are going to purchase a bull from another herd, hopefully he will have some sort of health screening done for diseases such as TB, BVD, brucellosis, and leukosis before stepping into your herd. You might manage every female in your herd perfectly to minimize the incidence of disease, but one animal (that darn bull) can ruin a lot of those efforts. Don’t let that happen.
There’s also another disease - Johne’s. You can test for it too, but if this new bull you're adding to the herd is young, there's a chance he won't test positive for Johne's even if he's been infected. It won't show up in a test until he is older. The next best thing is probably to explore the Johne’s status of the herd he’s coming from. Is it a clean, well-managed herd where some Johne's testing has been done, or are animals coming and going all the time with minimal management to prevent the spread of Johne's?
Remember, semen that is passed by natural service hasn't been tested and will vary in quality. Quality changes as the environment changes. Changes in the weather or the diet a bull is eating can sometimes have dramatic effects, so don't assume that the mere presence of a bull means that fertile breeding will continue 100% of the time. You'll need to monitor his reproductive success. He might simply get too fat from eating a loaded ration and need to move on.
Hopefully the genetic quality of your herd is moving in a positive direction. There’s no reason you need to go backwards or even stay stagnant if you've identified particular goals for your breeding program. So what is this bull doing for you? Ideally, he would be able to do more than simply get a few females pregnant. If a pedigree is available on a bull you're considering, take a look at it. If not, ask for information about his parentage. What was his dam like? Who are his sire and grandsire? Make sure he's a good fit for what you're after, and consider what effect he might have on inbreeding.
It probably doesn't need to be stated that safety is an issue with bulls. There have been, and continue to be, nasty accidents with bulls. In a matter of seconds, a bull that may have had zero history of any aggression towards people can abruptly change (or even eliminate) someone's life. It's a serious issue that can affect even the most careful operations. If you have bulls, or are ever working around them, please always keep this in mind. An aggressive, "no nonsense" culling program is a good idea.
Maybe, after thinking through the various issues, you’ll decide to discontinue your use of herd bulls. If that’s the case, I'm willing to bet that you'll be able to make up for them with other reproductive strategies and be satisfied with your reproductive success. There are a lot of options you can consider these days.
If you plan to continue using bulls in your herd, just remember that you might be paying more than you first think, so be careful to think about the variables and don't sell yourself short. You don’t want to shoot yourself in the foot by getting a “dud” and regretting the fact that you didn't get the right one.
Here are some related articles:
Do Away With Him
Are They Necessary?
Costs & Risks
Photo credit: www.anglindairy.net





