Grass Genetics Selection 101
By Allen R Williams, Ph.D.
To most people genetic selection can be a complicated task. There is so much data out there that many folks get lost in the translation. What to use and how much emphasis to put on each trait becomes an overwhelming issue. EPD’s, actual trait measurements, phenotype, pedigrees, ultrasound data, linear measurements, other people’s recommendations --- which do I use and why? With all the data available we often find ourselves floating in a sea of confusion.
On top of that, we also have environmental effects on genetic expression. The environment that our animals are raised and produced in can have a profound impact on how their genetics actually express themselves. This involves what they eat, the climate they are adapted to, exposure to pathogens, and many other environmental factors. This is often called epigenetics. Epigenetics is the study of the cellular and physiological phenotypic trait variations caused by external or environmental factors that switch genes on and off. It affects how cells read genes instead of being caused by changes in the DNA sequence. That’s a mouthful I know, but it profoundly affects what happens on the ground in our livestock operations.
I cannot possibly cover everything pertinent to genetic selection in a single article, so I will outline the basics of genetic selection in this article. I will follow with more detailed information relative to the impacts of our selection criteria and to epigenetics in future articles.
The Basics of Effective Genetic Selection
Let’s cut to the chase here. Since we are talking about genetic selection, we are discussing breeding stock. I will use cattle as the basis for our discussion, but the principles apply to other species of livestock as well.
The number one trait that impacts pure profitability in our herds is longevity. Yes, how long our breeding stock can stay in the herd and be productive. In the case of a beef herd, we are talking about how long a cow can stay in the herd before she is culled for any reason – failing to breed or rebreed, unsoundness, disease, injury, etc. For many years, when I was in academia, I worked with the national IRM program (Integrated Resource Management). That involved me collecting detailed production and financial data on hundreds of beef cattle operations. What I found in the analysis of that data was that the average beef cow has 4.2 calves in her lifetime before she is culled for any reason. However, it takes 5 calves in a lifetime before a cow breaks even on her investment, on average. So, that means the average beef cow in the U.S. never makes the producer any money. No wonder lots of folks say that “you can’t make any money in the cow business”. We are not making money on a cow until she has her 6 th calf and beyond. To do that we are looking at an 8 year old cow, if we start calving as a two year old. So, she has to last a long time and be highly productive that entire time.
We routinely have cows that last well into the late teens and even to 20 or so years old, having never missed a calf in their lifetime. Those cows are highly profitable and produce daughters that will do the same. To last that long they have to exhibit the other important traits that I consider to be the most critical. These are adaptability, fertility, and soundness.
Adaptability is just what the name infers --- the ability of your livestock to perform and perform well in your specific environment. This is not just the climate in your region, but also the forages that the livestock will be grazing, their ability to maintain adequate body condition in all seasons of the year, and even your individual management style and skill set. All heavily influence the ability of your livestock to adapt to your “environment”. Without adaptability, you cannot have longevity.
How do you select animals for adaptability? The best way to accomplish this is to pay frequent visits to the folks you purchase your seedstock from, whether that is bulls or females. You need to really know how they manage their cattle, what forages their cattle are exposed to, what is their grazing management plan, what supplements are used on the seedstock operation and why, are the seedstock pampered or expected to perform in similar conditions as your cattle. Do they have a similar breeding and calving season? Do they have a similar management style?
My advice is to not buy your bulls from sales where you have had no prior exposure to the seedstock breeders and do not know their programs. Never make your selection decisions based on numbers in a catalog alone. That means EPD’s, calving weights, weaning weights, yearling weights, etc. These numbers will not tell you anything about a bull’s ability to be fully adapted to YOUR farm and your management. Instead, do your homework and visit the breeders you anticipate buying seedstock from. Learn their operations, their breeding program, their management style. Ask to see the mature cow herd first, not the heifers or bulls for sale. The mature cows will tell you a lot about the adaptability of the cattle they are producing. I always ask to see the oldest cows in the herd, so I can gauge longevity. If they do not have many cows over 10 years of age, how can I expect their genetics to produce cows that will last past 10 years of age in my herd?
Fertility is an absolute requirement for a breeding herd. You simply cannot afford to keep females and males around that are not sound breeders. For cows, that means they must calve every 365 days or less and breed back within 90 days after calving each year. In addition, they must produce a live calf at weaning every year. That is their job. That is why they exist on your farm. You cannot make excuses for a cow and give her second and third chances to breed. Nor can you excuse her for failing to produce a live calf at weaning. Doing so will eventually propagate inferior genetics in your herd and cost you your profitability.
When I was an academic (university professor) with specialties in genetics and reproductive physiology, I used to think I was one smart cookie. I thought I could do a great job of replacement heifer selection and would use all the “tools” available. That meant using EPD’s, frame scores, pelvic area measurements, reproductive tract scores, phenotype, live weight measurements, linear measurements, etc. I was so bogged down in numbers (data) I could not see past my own nose. When I left the university, almost 20 years ago now, I got a lesson in reality. I became heavily involved in the grass fed beef sector and started having to select cattle that performed well on forages without being routinely supplemented. At that point, I realized that all my prior training and teaching was really just an impediment.
So, how do my partners and I select heifers today? Quite simple. We allow all heifers an opportunity to breed for a 60-70 day period, for calving at two years of age. After bulls are pulled, we ultrasound pregnancy test each heifer. Those that were able to conceive within the 60-70 day window bought themselves a ticket to the breeding herd. Those that did not breed bought themselves a ticket to the grass finishing herd. That simple. No EPD’s, no reproductive scores, no live weight data, no linear measurements. None needed.
For first calf heifers, if they fail to rebreed within 90 days of calving they go straight into the grass finishing herd as well. Since they are bred to calve first as a two year old (24 months of age), they are still well under 3 years of age when harvested. And guess what? Those first calf heifers that fail to rebreed will fatten quickly, marble well, and eat very well.
I must admit that this has simplified life significantly. No more pouring over data wondering which trait measurements are the most important. No more excuse making for the cattle. This is basically a form of natural selection that occurs within the micro-environment of our own farm. We make money with the heifers that breed and those that fail to breed. They either become mothers or meat. We win financially either way.
For bulls, it is quite simple as well. We select those that best match our desired phenotype and prove within the first year of life that they can perform well on a forage-based diet. They must be highly masculine at a year of age, with a crest to the neck, heavy in the shoulders, and excellent testicular development. In addition, they must be deep bodied with depth not only in the mid-section, but also in the heart girth and flank, with tremendous expression and explosion in the lower 2/3rds of the mid-rib. When viewed from behind, the widest part of the bull should be his mid-section. An 18 month old bull should be fully capable of breeding at least 30 females in a short breeding season. At two years of age, they should be able to cover 50 cows or more.
We tend to use multi-sire herds for breeding, so several bulls are placed with each herd. After birth of the calves, simple DNA parentage analysis is used to tell us which bulls performed and which ones did not. For those that did not sire many calves, their life as a breeder is over and none of their progeny are saved as replacement stock. This prevents us from propagating inferior, poorly adapted genetics.
Soundness is the final trait we will discuss today. Soundness is crucial to fertility, adaptability, and longevity. Without soundness, the cattle will fall quickly out of the herd. What is a “sound” animal? This is an individual that is sound in the feet and legs, in their overall skeletal structure, udders and teats (for females) and testicular develop (for males), eyes, and even their minds. I want an individual who has four well placed legs, can travel unimpeded, with no obvious defects to their feet and leg placement. This becomes increasingly important as an animal ages and gets heavier. If there are feet and leg problems they will manifest themselves in the older, heavier animals. For females, a sound udder and teats are critical to longevity. I absolutely refuse to deal with cows that have udder problems or balloon teats. They will cull themselves quickly. For bulls, the same goes for testicular development. If they do not have excellent testicular circumference and length, plus even testicular placement and orientation, I do not want them as breeding stock. You do not have to physically measure this – you can see this readily.
Good eyesight into old age is also an important criteria for good breeding stock. They have to be able to see to travel well, to perform, and to be desired breeding stock. In addition, they must be sound minded, meaning they must have a gentle and even disposition. When I was a young man, I thought it was fun to fool with bad tempered cattle. Now that I have some age to me, and a little bit more wisdom (that may be questioned by some), I realize that life is too short for bad tempered livestock. My body does not heal as fast as it used to. If I want a rodeo, I go to see one.
I do not want a rodeo on my home farm. These are the basics of sound genetic selection. Don’t make it more complicated that it has to be, or think you are smarter than everyone else. In the articles that follow, I will talk more specifically about what size our cattle need to be to be truly profitable, how to know when an animal is truly finished and ready for harvest, and how epigenetics impact everything we do on our farms.