Page 7 - Totaranui Angus Catalogue ebook

ANTAGONISTIC

TRAITS

direction but may inadvertently have to deal with a higher degree per kg premium (potentially over $10K for a unit of cattle – it’s
of culling to sale day if the wrong bull is used. being done now!) or make your store stock very sort after (if
they are identifiable – use the Angus Pure tags!).
Another common antagonistic trait is mature cow weight to
growth. As we select for growth, there is a tendency for mature To get IMF into your herd, you’ve got to do it in a way that
cow weight in the herd to increase, unless you look for bulls where doesn’t compromise your other commercially valuable traits, such
the mature cow weight ebv is less than the 600 day growth ebv. as growth. Look at your bulls and work out what their average
However, selecting bulls with mature cow weight too low can lead IMF ebv is. To lift that you will have to use bulls with an IMF ebv
to another antagonism of an increase in calving difficulty. of at least 2 above what you have been using, easier said than
done considering only half the genetic lift comes from the male.
Now on to marbling. There is a reason not all herds (stud and The bulls we have put into the 2 year old sale have ideally been
commercial) have chased this trait. It’s a very frustratingly selected to have good IMF but also above breed average for
antagonistic trait. If anyone knows Wagyu they will attest to growth. Also look at using Heifer Select, a genomics tool through
this, yes…they marble but it takes an extra year to finish them. Zoetis, to measure IMF potential in your replacements.
Amongst others, marbling is antagonistic to Eye Muscle Area and
Yearling Growth (Koots et all, 1994), or if you like, growth and Source of some of this interesting stuff - “SELECTING FOR
carcass in general. Over the years there have been curve bending CARCASS MARBLING AND MUSCLING BENEFITS AND PITFALLS”,
bulls that have broken this antagonism but these bulls have Jim Gosey Extension Beef Cattle Specialist Animal Science
only come to light through the efforts of those that have Department University of Nebraska, Lincoln.
selected for both traits and measured for marbling. These
bulls have grown, had carcass weight and marbled.

It’s taken us time to start to get consistent marbling across our
sales and it’s still a work in progress. Commercial breeders have
to make the same choice as we did, to either stay traditional or
to chase high value carcass traits that now can add up to a dollar

TOTARANUI 2YR OLD BULL SALE 5