Performance Line
Developing Genetic
Selection Tools
for Male Fertility
By Tonya Amen, National Center for Beef Excellence
Fertility is the most economically important trait
in beef cattle, however, only recently have we
begun to develop selections tools for female
fertility. Since one bull may be used to breed
numerous females via natural service and
even more through AI, fertility may be more
important in a specific bull than in a specific
cow, yet male fertility has been virtually ignored
in terms of development of genetic selection
tools. According to Katselic et al (2012), few
bulls are completely sterile, but in an unselected
population, 20 to 40% may have reduced
fertility. This provides excellent opportunity to
address fertility from the male standpoint.
Sub-fertile bulls can cause all kinds of issues
that impact your bottom line and just a few
of these include reduced weaning weights
(due to longer calving seasons that result
from delayed conception), increased culling
rates and increased risk of injury to bulls and
cows as the result of repeated breeding.
According to Dr. Megan Rolf, “I think we have a
hole in our genetic evaluation systems relative
to fertility and we don’t currently turn in any
of the data we already collect that could be
used to help build selection tools for male
fertility. Though we have focused on female
fertility, the heritability on male fertility traits
actually appears to be higher than for female
fertility. So, we could arguably address male
fertility more easily than female fertility if we
can turn in enough high-quality data on the
appropriate traits to build the selection tools.”
With this in mind, the North American Limousin
Foundation has agreed to collaborate on
a project with a team of researchers from
Kansas State University to investigate the
important trait(s) of male fertility.
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