Management Decisions vs Genetic Selection
Some things in life are pretty obvious. If you get your finger cut off with a table saw, you know without a shadow of a doubt that the saw blade was responsible. A more difficult question to answer is “which tooth?” As we learn more about genetic selection, our saw, we start asking a lot more questions, our teeth. Topics such as genetic selection for fertility and accuracy of E.P.D.’s on virgin animals which once seemed straight forward, have now been shook to the core. Some people are hanging out on to the ledge for dear life while others opted for the parachute. I think the most confusing thing to decipher today is good management vs managing genetic selection. Surprisingly, they are not the same thing. Let’s explore each one in turn.
Management decisions mostly come down to economics. Ranches that have high wintering costs absolutely need to get rid of every cow that is not returning them healthy and marketable progeny. These actions may inadvertently help select for genetic propensity for fertility, health, and growth. They just don’t do nearly as good of a job as we would hope. This decision also helps insure the cow herd is environmentally adapted and it also helps get rid of cattle that are harboring sub-clinical diseases and parasites loads that are unsustainable. When selecting for heterosis, it allows the cow herd to be more adaptive to the climate, environment, and region. This ends up becoming more of a management decision. There are a lot of commercial cattleman that track birthweight and weaning weight as information to make genetic decisions. Again, genetics are a part of it. However, too often only raw data is used in these scenarios. They are not adjusted to 205 days of age and then ratios are typically not formed. This in essence is a measurement of the rainfall that year and how you are managing the cow herd. If weaning weight is low, you might not have the genetics to get it done. But if you aren’t tracking adjusted data and have not DNA tested the cows, it’s hard to say how much genetics are having an effect. Since nutrition, disease, and environment play such large roles in this data it is hard to eliminate variables. A recent article published by the Red Angus Association described the update in the LiveWiRed project. This project is where one Gelbvieh cow was flushed to 5 different Red Angus sires. Three sires were high growth and high carcass while two sires were low growth and low carcass. These calves were recently weaned and data was collected. The adjusted average for the whole group was a 421 lb. weaning weight. This is not very good. Rightfully so, it was a poor year for nutrition and weather was considered a large factor in the actual data. The Red Angus Association has an average spread of 42 lbs. between fall born bulls and fall born heifers. In this study, there was only 19 pounds different. This is another sign that environmental factors inhibited full expression of the difference in genetics. Without adjusted data, E.P.D.’s, and/or DNA markers, selecting for genetics based on this data would be tricky at best.
Managing Genetic Selection-
Pure genetic management happens when we ELIMINATE (as best we can) environmental factors. And although certain traits are selected and measured for economic merit, genetic selection itself is not economically driven. It is driven by biology. In order to make progress in genetics we must measure with data which is adjusted to reduce any variable other than genetics. Although it is not a perfect science, but that is the goal. When selecting for pure heterosis we need to measure the amount of heterozygosity we will be getting with each mating. This is managing genetic selection. Also, managing genetic selection becomes front and center when measuring for production traits affected only by genetics. Going back to the LiveWiRed project they found that once all data was adjusted, measured, and graphed, there was a statistical difference in genetics. They compared Sire A from the high growth genetic pool to Sire B from the low growth genetic pool. The average difference in adjusted weaning weight was 22.6 lbs. This wasn’t nearly as large as the difference in weaning weight E.P.D.’s which was actually 40 lbs. Again, the lack of expression was blamed on poor nutrition/environment. What I’m trying to point out is genetic selection was still proven and selected for, even in less than ideal environments and extremely low cattle numbers. The key is adjusted data, DNA testing, and known lineages/E.P.D.’s.
Confused yet? Let me try and apply these concepts:
We have all heard the lecture of how you can’t keep open cows. If you do so, you are “breeding” infertility into your herd. Maybe, maybe not. In fact, it is a widely-held belief that fertility and reproductive traits are lowly heritable. If this is a widely-held belief, why is everyone always saying to get rid of open cows? But I digress… let’s say fertility and reproductive traits is only 20% heritable for a nice round number (the average is a tad more or less than this depending on breed). This means that for every 10 cows you cull for being open, 2 cows are being culled because of genetic infertility. Sure, you are still selecting for fertility. But how much progress are you making if you aren’t measuring with great record keeping? It’s cowboy code to never ask a guy how many cows he runs, so I’m not asking. I’m asking you to visualize how many you have and be honest with yourself. It takes big numbers to make statistics make sense. Dave Pratt with Ranching for Profit is often pointing out you need at least 400 head of cows to statistically keep your own replacements for commercial cattleman. By all standards that is quite a few. The shortcut to genetic progress without statistically relevant groups of cattle is through better lineage tracking and through DNA testing. So, if we aren’t tracking the cattle we have and tying fertility back to male and female lines, we might not be making a lot of progress genetically. Especially if we are unaware of the male lines that have the largest impact. A better route would be to utilize DNA technology and buy genetics from seed stock operations that do track fertility in large groups of cattle.
I am imagining many of you protesting and preparing counter arguments already. I never said to not get rid of open cows. I did not say we shouldn’t put downward pressure on fertility with shortened calving seasons. However, I want to point out that culling open cows is a great MANAGEMENT decision. This is a management tool that is very important. It helps us select for cattle that will fit our ENVIRONMENT. They simply may have a more robust rumen microbial population more suited to digesting the native grasses to the area. It may lie in epigenetic responses that, as of now, is hard to measure on a commercial scale. When focusing on culling cows, this management decision alone will not make huge strides from a strict GENETIC selection standpoint for fertility. We now have tools through E.P.D.’s and DNA to help us sort cattle for fertility more efficiently.
This may dishearten some. Please don’t let it. All this does is allow us to be more exact about what we do. We need to know where we stand genetically by testing and see if we are behind, par, or above and beyond. We need to review management protocols and be flexible. Realizing not every mistake is because of poor genetics or because of poor management. This allows you one step closer to seeing what is the most powerful decision you can make to influence profit on your land with your livestock. No longer do you have to rely on one size fits all solutions. Identify problems, implement specific solutions.
I get a lot of windshield time, please feel free to call me at 402.310.5056 or email me at firstname.lastname@example.org with any questions, comments, or to just talk cattle.