Everything in life is a trade off: Marry
the woman of your dreams; then brace for the in-laws. Fortunately, genomics has
the potential to change the rules when it comes to beef cattle, enabling
producers to enjoy the upside of key traits without enduring the downside.
Tapping that potential is the focus of the Genome Alberta project targeting
traits of interest to the beef industry such as feed efficiency, productivity
and methane emissions.
“The profitability of beef cattle
production is determined by multiple traits that are sometimes negatively correlated,”
said Dr. Changxi Li. Dr. Li is a research scientist with Agriculture and
Agri-Food Canada (AAFC) and AAFC Professor and Chair of Bovine Genetics, Faculty
of Agricultural, Life and Environmental Sciences at the University of Alberta.
“That means if you select for one desirable trait, such as growth, it may have
a negative impact in another area by increasing the animal’s feed
requirements.”
To counter that effect, researchers are
building up an index that considers multiple traits at one time and determines
the economic weight of each trait based on costs and revenues. As an example,
for every 1 kilogram that you increase body weight, how much extra will that
add to production costs and net revenues?
“Once we calculate the exact economic
weight and value of these traits, we can use that information to construct a
multiple trait selection index for each animal,” said Dr. Li. “From there, we
will define the most important traits to include in the index based on their economic
weight and genetic components like genetic and phenotypic variances,
heritability and molecular breeding value.”
Staying true to their values
Through all of these calculations, the
molecular breeding value is a key component for each animal and each trait in addition to the economic weight. Where
scientists lack phenotype information on an animal, those values can be predicted
based on the animal’s DNA profile (i.e. genomic prediction), and be used to
produce the index that weighs one trait against all the others. In this way,
they will know from day one if a cow will be profitable, and be able to
identify the best animals when it comes to lifetime productivity.
“For the replacement heifer index, we are
considering several different traits, for which we have data from 411 animals
over 11 production cycles,” said Dr. Tiago Valente, a post-doctoral researcher
in Animal Breeding and Genetics at Livestock Gentec, University of Alberta.
Those traits include heifer birth weight,
weaning weight, retained heterozygosity or hybrid vigor (the improved function
of any biological quality in a hybrid offspring), dry matter intake, residual
feed intake or feed efficiency, cow productivity, age at first calving and
number of progenies from 1 – 5.
“We chose these traits for the index
because we view them as having the greatest impact on revenue,” said Dr.
Valente.
In selecting them, researchers are looking
for three aspects in regard to replacement heifers: new traits with additional
costs, such as feed efficiency; readily accessible traits that are easy to
measure, like age of first calving; and late phenotypes such as the number of
progeny.
“Our hope is that we can use this selection
index to help producers choose the best cows that produce the most revenue and
the least methane, thereby supporting sustainability,” said Dr. Valente.
While these are exciting times for both
scientists and beef producers, Dr. Li has a couple of key reminders.
“It is important to emphasize that genetics
provides potential and management helps deliver that potential. As genomics
research evolves, new tools like genomic prediction of genetic potential or of
retained hybrid vigor can aid producers in selecting the optimal genetics or
breed combination for their herd. This will help them make breeding and selection
decisions for improving cattle performance, including traits that are more
difficult and expensive to measure such as feed efficiency, fertility and
methane emission.”
Dr. Li also stresses that genetic
improvement in a herd is cumulative and sometimes progress is slow, so the best
approach is to continuously select for the traits you desire over many breeding
seasons.
Now if you could only choose your in-laws…
