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Selecting cattle for disease resistance
Pop quiz: If you could buy a new herd bull that would “fix” your cow herd in one of these areas, which would you most desire?
A. Marbling score
B. Feedlot average daily gain
C. Feed intake
D. Weaning weight
E. Respiratory disease incidence
F. Carcass yield grade
My guess is that if you’re a feedlot operator, you’re going to say average daily gain. And if you’re a cow-calf producer, you’re going to say weaning weight.
Good answers, but neither holds a candle, economically speaking, to the bull that can solve your herd health problems, particularly BRD (respiratory complex). A recent analysis by Alison Van Eenennaam of California-Davis says that the ability to select cattle for disease resistance will overpower everything else because of the tremendous cost of sick and dead animals. She shared her analysis at the Cattle Industry Convention this week.
Her analysis compared all of the above characteristics on a relative basis to the ability to select animals for yield grade. Here’s how they ranked by relative importance to yield grade:
Marbling: 2.6 times more valuable
Feed intake: 4.6
Weaning weight: 5.7
BRD incidence: 37.7
In other words, decreasing BRD incidence is the most valuable trait in this terminal sire selection index. In Van Eenennaam’s analysis, she assumed a 10% BRD incidence at the feedlot with 10% mortality of them, a 13% reduction in ADG because of BRD, and the cost to diagnose and treat a BRD calf was $44.
Relative to weaning weight, selecting for BRD resistance is 5 times more valuable economically than selecting for weaning weight.
The problem with this is that we don’t have good ways of selecting bulls or other animals on the basis of disease resistance. We have many more gene markers and expected progeny scores for weaning weights and the other traits.
But that may be changing, says Mark Enns, animal scientist from Colorado State University who was on the program with Van Eenennaam. “We know there are genetic differences among animals,” says Enns. “At least that’s true for BRD. We just lack good tools to make decisions. It’s going to be genetic markers, and carcass progeny tests from the breed associations that get us the answers on genetic disease resistance. I predict we’ll have some useful tools for beef producers in two to five years. When we can select animals on the basis of disease resistance, it’s going to bring us some tremendous economic advantages.”