Estimated reading time: 8 minutes
- Genetics are a crucial aspect of the livestock industry, influencing the success or failure of the entire value chain, making it the responsibility of seedstock producers to adapt their genetics to their environment, resources, and objectives.
- Various selection tools such as pedigree, phenotype, EBVs/EPDs, and genomics are available to breeders, and they are useful when applied with a balanced and contextual approach.
- The selection criteria differ significantly between animals used in maternal breeding programs and those for terminal purposes, with profit traits like fertility and adaptability forming the foundation for maternal programs.
- EBVs/EPDs are useful if used in context, but breeders must trust the accuracy and relevance of the numbers being provided by breed associations, ensuring they align with their objectives, resources, and environment.
- Cattle breeding is both an art and a science, where breeders must balance scientific tools with the nuanced understanding of traits and selection processes.
Genetics are the point of the arrow when it comes to the livestock industry. Although genetics are of equal importance to disciplines such as herd management, nutrition, animal health, marketing, forages, record-keeping and human resources, genetics remain the prime mover.
As the last link in the value chain, the consumer being the first, genetics determine how the rest of the value chain flourishes or fails. It is the duty of the seedstock producer to act as a scientist with their ranch or farm being their laboratory. By adapting their genetics to the particular environment, resources, and objectives they are dealing with, the seedstock producer experiments, invents, and proves or disproves genetics.
Selection tools
There is an abundance of selection tools available to cattle breeders. These tools vary from traditional to cutting-edge and are all used to differing degrees within both the beef and dairy industries. The selection tools discussed in this article include pedigree, phenotype, production-based culling, in-herd indexes, estimated breeding values (EBVs)/expected progeny differences (EPDs), and genomics/genomic-enhanced EPDs. All these tools can be useful when making breeding decisions, if used in context and with a non-biased and balanced approach.
The first objective to be considered is whether the animal you want to breed is destined to be utilised in a maternal breeding programme or as a terminal animal for beef (note that the selection criteria for these two options are vastly different).
A premise to consider is that there are two types of traits in a maternal breeding programme: profit traits which include adaptability, functional efficiency, fertility, and longevity; turnover traits which include growth, muscle, milk, and marbling. Turnover traits are very important but are meaningless if profit traits are not used to lay the initial foundation.
Every breeding decision needs to be made according to objectives, resources, and environment. Without matching these decisions to these three factors, there is a good chance of missing your target.
Read more about Climate indices for informed agricultural decision-making.
Pedigree
The animal’s pedigree is extremely valuable when making selections. Understanding or remembering pedigrees is fast becoming a lost art in the age of genomics. However, pedigree is the motherlode from whence all these technologies have sprung.
Traits such as mothering ability, libido, temperament/aggression, well-being, and hardiness are immeasurable in any accurate form by any technology. The knowledge of the ability for certain bloodlines and cow families to work together is where the art of breeding comes to fruition. A lot of selection criteria are too nuanced for scientific method.
Phenotype
Phenotype is extremely useful, even essential, when making breeding decisions. A lot of what data or EBVs/EPDs are telling you can be seen in the animal itself. The analogy that I like to use is that when you are told that it is raining outside, you can simply open the curtains and take a look instead of checking the weather application on your smartphone. Growth, fat, muscle, milk, calving ease, and a host of other traits are as easily observed with the human eye as they are read off a chart. When doing phenotypic selections, you need to first consider if the animals are maternal or terminal.
In maternal animals, cattle need to be able to eat, walk, and reproduce. Focussing on the profit traits (adaptability, functional efficiency, fertility, and longevity) is first and foremost. Balance is also essential. This includes physiological and endocrinological balance, carcass balance (muscle/fat ratio), skeletal balance, and hormonal balance. High inherent body condition (easy fleshing ability/do-ability/constitution) plus hormonal balance equals fertility.
In terminal animals, the fundamental traits remain vital. In animals bred for a high-yielding carcass, factors to focus on are a high growth rate and large rib-eye area. Dimension is essential, too, as three-dimensional animals produce heavy carcasses. Carcass balance is still essential as fat cover is needed for good grading and fleshing ability, while muscle is required for yield.
Structural soundness is essential in terminal animals, too. Structurally unsound animals tend to founder and go lame when in the feedlot. These animals lose their appetite and do not gain appropriately. In addition, steers have sisters and mothers out grazing on pasture their entire lives, so ignoring structure in terminally bred cattle is dangerous.
In terminal animals bred for high-quality eating experiences, such as the Japanese and South Korean breeds, the logic remains similar in terms of structural integrity. Carcass balance leans further towards marbling traits with muscle being necessary but not pinnacle. Waxy horns, a sharp poll (or a fine ridge between the horns), oily skin, silky hair coat, flat and fine bone with small joints, and a flatter muscle shape all augur well for high-marbling carcasses.
Production-based culling
I use this term where replacement females and breeding bulls are selected based on the fact that their dams, grand-dams and great-grand-dams have simply jumped over every hurdle the breeder has placed in front of them regarding criteria to remain in the herd.
These include reasonable nutritional supplementation, age at first calving, inter-calving period, short breeding seasons, cow/calf ratio at weaning, minimum weaning weights, unassisted births, etc. This is a fast way of building a profitable, consistent, adapted and uniform herd.
In-herd indexes
In-herd indexes were the primary arithmetic used for cattle selection prior to the arrival of EBVs and EPDs. These in-herd indexes remain a vital tool when customers purchase animals from a reliable seedstock breeder, or when the seedstock breeder is presenting their product to the market. They give context to how animals have performed in their given environment and herd. It is important to remember that not all herds are the same.
A 100 index in a progressive herd is superior to a 100 index in a less progressive herd. However, if you are familiar with and utilise a registered herd for your seedstock needs, using in-herd indexes for selection purposes is very valuable.
EBVs and EPDs
EBVs/EPDs/breed population indexes are widely used worldwide by animal producers. These numbers are based on the in-herd ratios of the animal itself, as well as the in-herd-indexes of its ancestors, siblings, relatives, and offspring.
EBVs/EPDs can be extremely useful if used in context and when matching them to objectives, resources, and environment. As a breeder, you need to decide whether you trust these numbers being published by their specific breed society/association. If the breeder believes that they are relevant and that most breeders are measuring everything, all the time, accurately, honestly, in large numbers and in the same environment, then it is important to remember that the number being produced is an objective one. Therefore, no EPD/EBV can be good or bad. It depends on your objectives, resources and environment.
In maternal breeding programmes, it is essential to note that the sex hormones only start when the growth hormones stop. Therefore, if you select for high growth numbers, you are directly selecting against fertility. Selecting for fertility starts with high inherent body condition and hormonal balance. On an EBV/EPD chart that would mean higher back/rump fat numbers and higher scrotal circumference at a year of age. Selecting for top 5% weaning and yearling weight continuously will create higher birthweights, leaner, later maturing and less fertile cattle with higher energy requirements.
Selecting for high inherent body condition and early sexual maturity will produce cattle with high relative (reaching mature size early) growth rates, low energy requirements, and high fertility. If you feel that the average animal in your breed is big enough, it makes no sense to require anything more than the breed’s average EPD/EBV yearling weight or mature cow size. Similar logic works with all traits.
Sexual dimorphism
You’ll notice that herds that have focussed heavily on growth and carcass traits for some time will have a lack of sexual dimorphism in their cattle. There won’t be much difference in size and shape between the bulls and females. This sexual monomorphism is an expression of hormonal imbalance and subfertility. Bulls tend to be less masculine, and females tend to be less feminine. Sexual dimorphism occurs when selection for high inherent body condition and hormonal balance is practised. These animals mature earlier and are more fertile. The bulls are significantly larger and shaped and coloured differently from the females.
Publishing trait leaders is counter-intuitive in my opinion. For example, why is less fat better than more fat when publishing a fat trait leaders list? Doesn’t it depend on the objectives, resources, and environment of the breeding programme? Big, lean, late-maturing cattle are great for feedlots and processors, but devastatingly expensive to keep for cow-calf operators. What good is giving the tools of a top 1% for a trait such as milk to marketing companies to run with? Top 1% for milk does not even make a profitable dairy cow, never mind how destructive it proves to be for beef cow operators.
In terminal breeding programmes, traits such as weaning weight, yearling weight, ribeye area, and intramuscular fat become important. Managing birthweight to where it is functional is also vital.
Genomic enhanced EBVs/EPDs
Genomic enhanced EBVs/EPDs are based on the same premise as EBVs/EPDs. However, the actual genetics of the animal are taken into consideration and not just the average EBVs/EPDs of the sire and dam at birth. GE-EPDs/GE-EBVs increase the accuracy of an EPD/EBV for an animal with no offspring to have the same accuracy of that same animal if it had had up to a dozen offspring. If the premise of EPDs and EBVs make sense to the breeder, then GE-EPDS/GE-EBVs will work for them.
If, however, a breeder does not agree that the data being used to create GE-EPDs/GE-EBVs is measured entirely, honestly, accurately, in large numbers, all the time, eliminating environmental influence by most breeders, then it is probably better to revert to the other tools in the selection toolbox (phenotype, pedigree, in-herd indexes, and production-based culling).
Cattle breeding is as much an art as it is a science. Artists and scientists alike are passionate and obsessive about their work. Context and nuance are key.
For more information, email pjbudler@gmail.com or visit www.pjbudler.com.
