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Cattle selection decisions based
on objectives, resources and environment
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By: PJ BUDLER, 2022
Genetics is the point of the arrow when it comes to the
livestock industry. Although genetics is of equal importance
to disciplines such as herd management, nutrition, animal
health, marketing, forages, record keeping, and Human
Resources, genetics remains the prime mover.
As the last
link in the value chain, the consumer being the first link,
genetics determines 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 cattle
genetics to the particular environment, resources, and
objectives they’re dealing with, the seedstock producer
experiments, invents, and proves or disproves genetics.
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 I’ll discuss in this article include phenotype,
pedigree, in-herd indexes, Production-Based Culling, EBVs/
EPDs, and Genomic-enhanced EPDs. All of these tools can be
useful when making breeding decisions, provided that they
are 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
program or as a
terminal animal
for beef. The
selection criteria for these two
options are vastly different, and I’ll go into more detail
in paragraphs to come.
A premise to
consider is that there are two types of traits in a maternal
breeding program: profit traits, which include adaptability,
functional efficiency, fertility, and longevity, and
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’s a good chance of missing
your target.
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 mother lode from
whence all these technologies have sprung. Traits such as
mothering ability, libido, temperament or 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 the scientific
method.
Phenotype
is
extremely useful, and I’d say 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, one can simply open the curtains and take a
look instead of checking the weather application on one’s
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 from a chart. When doing phenotypic
selections, one needs to first consider if the animals are
maternal or terminal.
In
maternal
animals,
cattle need to
be able to eat, walk, and reproduce. Focusing on the Profit
Traits (adaptability, functional efficiency, fertility, and
longevity) should come first. Balance is 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,
bred for
high-yielding carcasses, the fundamental traits remain
vital. 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 in the feedlot. These animals lose their
appetite and don’t gain appropriately.
Also, 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, like 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
is a term I use
where replacement females and breeding bulls are selected
based on the fact that their dams, grand-dams, and
great-granddams 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, intercalving 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 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 one is
familiar with and utilises a registered herd for their
seedstock needs, using in-herd indexes for selection
purposes is very valuable.
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
(Expected Breeding Values)/EPDs
(Expected Progeny Differences) can be
extremely useful if used in context
and
when matching them to objectives, resources, and the
environment. As a breeder, one needs to decide whether one
trusts 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 one’s objectives, resources, and environment.
In
maternal
breeding programs,
it is essential
to remember that the
sex
hormones only start when the growth hormones stop.
Therefore,
if one selects for high growth numbers, one is directly
selecting against fertility. Selecting for fertility starts
with a 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.
Continuously selecting for Top
5%
Weaning and Yearling Weight
will create
higher birth weights, leaner, and 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 one feels that the average animal in one’s 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 applies to all traits.
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.
You’ll notice
that herds that have focused 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 counterintuitive 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
program? 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 the
Top 1% for a trait like Milk to marketing companies to run
with? Top 1% for milk doesn’t even make a profitable dairy
cow, never mind how destructive it proves to be for beef cow
operators.
In terminal
breeding programs, traits such as Weaning Weight, Yearling
Weight, Ribeye Area, and Intramuscular Fat become important.
Managing birth weight, to where it’s functional, is
important.
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 as that same animal if it had up to a dozen
offspring. If the premise of EPD’s and EBV’s makes 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: these
being Phenotype,
Pedigree, In-herd
Indexes and Production-Based Culling. |
