Fertile Ground

Research has shown that fertility is a significant driver of profitability in the cow/calf industry. Work by Melton (1995) shows that in a traditional type of system fertility is 5 times as important as growth and 10 times more important than carcass merit to cow/calf industry profit. Even in more integrated systems such as retained ownership, fertility will double growth and carcass merit as a driver of profit.

Working in the genetic field we often run into the issue of low heritability regarding fertility traits, and people may consider this to mean that we can’t make progress on fertility through genetic selection. This is worth diving into, as fertility is such an important piece of the profit puzzle.

Firstly, it is important to recognize that the traits we can and do make progress on are often progressive or linear, and that as we apply increased management, we see increased performance and spreads between cattle. Let’s look at a growth example. If we examine cattle for differences in growth and limit the diet, we

will still see spreads across the performance spectrum. As we improve ration quality and increase overall rate of gain, we will actually see a wider spread expressed in a lot of groups and the expression of genetics enhanced. In oversimplified terms, a calf with genetics to gain 6 pounds per day, will not be able to do that on a diet of 15 pounds of slough hay. We generally manage for expression of the trait.

Fertility is a bit of a different bag of tricks. Many of the ways we measure fertility are “all or nothing” traits. A cow is either bred or open but can’t be halfpregnant. She either weans a calf or she doesn’t. There are some traits that are a bit more linear, such as days to calving or age at puberty, but generally speaking a cow either makes it or she doesn’t. This naturally means that figuring out the genetic component is harder, but it also leads to the second part of the problem. When we manage for growth, or carcass, improved management generally increases the expression of the trait and thus

the variation that we can measure. With more variation expressed it is easier to pick the animals that fit the direction we want to go. With fertility it is the other way around. Improved management tends to decrease variation. Again, let’s look at an oversimplified examFertility is ple to make our point: If we had a cow herd of 100 cows and such an gave them no preferential treatment, no mineral, no health program, etc. it is posimportant piece sible that we would have a 60% conception rate. There is a lot of variation to measure of the here, as 40% of the cows are open. Pressuring the cows in this environment quickly profit puzzle sorts the wheat from the chaff. Conversely, most operations in their right mind won’t do this as the economics of this scenario would be devastating. To maintain an acceptable conception/calving rate a manager may feed mineral, manage body condition and implement a vaccination protocol. Maybe we do everything “right” and now have a conception rate in excess of 95%. We have successfully improved our fertility, but have removed variation,

as we now only have 5 or fewer cows in our 100 cow herd to inform us of infertility. This is a major reason why fertility traits have a lower heritability than performance traits. By managing for pregnancy, we have limited variation in fertility.

If we accept the fact as seedstock breeders that we are in the business of genetic improvement, this creates a conundrum, so how do we overcome it and create real genetic improvement in fertility that is so important to commercial profitability.

While there are a long list of answers, there are a couple of basics that are really important and relatively easy to do.

COMPLETE HERD REPORTING

Reporting on the success/failure of each cow to conceive, calve and wean a calf is paramount to genetic improvement of fertility. The reality of a farm or ranch is that a calf may die before weaning, or that it may “slip” through the chute when it is time to weigh. It is still important to report breeding data on every cow, conception on every cow and the fate of the calf for every cow. This is available through the CGA’s performance program and is a core, fundamental of how we objectively assess fertility.

DNA TESTING

I really appreciate that DNA testing of sale bulls and elite genetics is a great marketing investment, however high density (100K ) DNA testing of the cow herd is a great GENETIC investment. New DNA technologies allow us to assess the genetic merit of a female with much greater accuracy at an early age. This can be a key driver to determining genetic differences in fertility.

POOLING DATA/GENETIC EVALUATION

Because of the way we manage cows for pregnancy, we require more records in order to have a meaningful assessment of the genetic contribution to daughters that calve repeatedly over time. One of the ways we increase records is to participate in a multi-breed, multi-breed association genetic evaluation with International Genetic Solutions (IGS). Not only does partnering help to increase the number of records available, but sharing the load also helps us to invest in enhanced science to better determine the genetic factors involved in cow herd fertility.

IGS currently provides an evaluation for Stayability (probability of cows staying in the herd) is working on other fertility evaluations such as heifer pregnancy.

Fertility is an essential driver of profitability for the beef industry and deserves attention at the genetic level. Because of our good management it is important that we provide data on as many cows as possible and work with others to provide an accurate assessment of genetic differences in these traits that really matter.