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While many before me have also found this to be worth paying attention to, maybe you may too!

While bulls tend to have 5-10 times as many flies on them as a cow will, due to high testosterone levels, Bulls are a great place to quickly see your management and genetic progress.

They say a bull is 50% of the herd. So, that said, I took it to heart when I noticed I owned a bull that had few flies in the summer. While I grant that we don’t have the same fly pressure that might be found in other states, I did find that some cows were just covered in flies, and others had few if any like the cows next to her.

So being the forward-thinking kind, I wondered if there was some genetic component to the bull with few flies. Here are some of my observations:

  1. bull had a mother with a short hair shiny coat.
  2. bull had short hair and a shiny coat as a calf, with few flies.
  3. he was chasing cows in heat at a very early age
  4. he didn’t get much of a long hair coat his first winter
  5. he was the first to shed out in spring
  6. he was one not hanging in the stock pond, he wasn’t in need of hiding from the flies.
  7. he was heavier and more masculine from what seemed a lower stress level
  8. flies still didn’t really bother him as a yearling when compared to steers and some females
  9. his offspring had way fewer flies than their mothers
  10. the offspring of his offspring had an even larger advantage of fewer flies when the next generation bull also had few flies.

I believe the hereditability to be around 60+% in the first generation. With some cows in our herd at 16 years old, I have noted the subsequent generations of change.

How to find the bull?

  1. select 5-10 top choice bulls from 1 or several farms for your new herd sire
  2. observe the bulls in fly season.
  3. take into consideration different management practices that might mask the true fly resistance like use of fly control of any kind (including in mineral)
  4. when you have it narrowed down to just a few top choices of bulls, choose the 1 with the fewest flies.
  5. use your choice bull to add fly resistance in your herd.

It may take more than 1 generation to get to the point where 70-90+% of reduction of flies takes place.

Make sure animals have access to good loose salt and loose mineral that matches the needs of your land and water. (blocks are convenient, but not always in the best interest of the cow’s needs) for the short term, using ACV can help reduce flies as well. offer at the rate of 1 oz per gallon water, or free choice.

Another option is fly predators or fly traps.

But the most effective method is to move the cows every few days to a new area. Rotational grazing helps break the cycle of flies. Cows are a long way away by the time a fly hatches and can fly. allow dung beetles to do their job.

Chemicals can kill them too. They do more than live on fly larva. They drag balls of manure into the ground.

When it comes to predators, they know that if they eat all the prey, there will not be any to make the next generation.

Do consider a mixed management approach to fly control. There are enough studies to show what pests cost a rancher per head in reduced gain. Consider genetics to make long-term advances in your fly control plans.