Table of Contents:
- Do You Want Progress Or Change In Cattle Breeding?
- More management than genetics
We have great tools; but, because of genetic and environmental antagonisms, I think we need to be satisfied with slow change in a balanced approach – maintaining or slowly improving genetics for cowherd productivity.
In my lifelong learning, I’ve relied on many sources but the most meaningful help has come from two of them:
Experts from the academic world who have the confidence of their peers and their students, have learned to work and communicate effectively with farmers and ranchers, and whose work addresses economically important questions.
- Farmers and ranchers who are possibility thinkers, pay attention to the science, learn from each other, want to know the truth and adopt practices and careful decisions that make them more profitable.
It is from this perspective (paying attention to the science and observing the practices of profitable commercial ranchers) that I make the following observations on cattle breeding and the way we select and cull.
Years of observation suggest that the most profitable ranches have cow herds that are at, or just slightly above, average for most economically important traits. The most profitable herds also have lower-than-average milk production. Trying to push a herd beyond average for an environment usually comes with a cost in feed or stocking rate.
There are many genetic antagonisms (unintended consequences) which can vary from almost imperceptible at first to fairly significant.
We can make rapid genetic change, but it doesn’t always yield economic progress. Looking at the dairy industry as an example, we see that, if you select primarily for milk, you will get lots of milk. You will also get significant inbreeding as a result of extensive use of artificial insemination (AI) to closely related sires, poor fertility, poor survivability, many health issues and lots of cost. To a lesser extent, I think that focused selection in beef cattle for high growth and carcass grade has yielded some of the same effects.
- Please understand that EPDs and genomically enhanced EPDs work, but too many people have used EPDs as a tool to strive for “maximums.” Maximum is seldom, if ever, the most profitable course.
Improvement carries a cost
Most improvement in performance comes with a cost. Often, that cost is in the reduction of performance in another trait, a reduction in stocking rate, or higher feed costs, each of which can take several years to become obvious. We need to be sure the added revenue is greater than the added cost.
The use of AI, embryo transfer and today’s genomically enhanced EPDs, without great care, can lead to a significant increase in inbreeding for the most popular breeds.
If cell division to form egg and sperm happened for each gene pair individually, I would not have so much concern. But cells divide a chromosome at a time, which means that to get the good stuff on a particular chromosome, you will also have to take whatever else happens to be on that chromosome – the possible antagonisms.
The relatively new study of “epigenetics” suggests that environmental factors may turn genes on or off. I think one might further suppose that environmental factors can reduce, enhance or even modify the effect of genes. Genes also have effects on each other – most of which are unknown and unmeasured. That’s just the way complex systems work.
- Many geneticists and a number of seedstock breeders are promoting the use of selection indices. The index becomes a composite of the “economically relevant traits.”
In putting the index together, each trait receives a weighting based on heritability and economic importance. From environment to environment, the relationship of heritability from trait to trait is seldom the same (though it may be close). The relative economic importance of each trait can also vary from place to place and from time to time. There is just enough skeptic in me (I call it being careful) to wonder if the economic weighting for each trait in the index was done correctly for my objectives.
Being a “systems thinker,” considering the forgoing observations and recognizing that the use of EPDs can move us toward or away from our profit objectives, I want to suggest the following combination of management and genetics as a method of herd improvement:
Cull cows that aren’t doing what you want them to do. Don’t expect careful culling to be a big genetic trend changer. It won’t be. But, it will keep your herd cleaned up, functional and easy to manage. It will help you avoid keeping offspring from the poorest few. I have noticed that, when culling for unacceptable disposition or performance, you only have to remove a few each year to keep problems at a low level and to make life easier and much more enjoyable.
- Use low-cost development and a very short breeding season for yearling heifers, exposing significantly more than will be needed. If you start with heifers that can be developed at a low cost and get pregnant in less than 30 days, you will have better cows raising better calves and with better rebreeding rates. Naturally you will sort off the real misfits before breeding.