Super bull 2014!
Here's a one-question pop quiz to test your herd health-management strategy: If you could buy a new herd terminal bull that would produce superior offspring in one of the areas shown below, which would give the most economic value?
A. Marbling Score
B. Feedlot Average Daily Gain
C. Feed Intake
D. Weaning Weight
E. Respiratory Disease Incidence
F. Carcass Yield Grade
If you're a feedlot operator, you're probably going to say B: Feedlot Average Daily Gain. And if you're a cow-calf producer, you're most likely going to say D. Weaning Weight.
They're both good answers. But neither holds a candle – economically speaking – to E. Respiratory Disease Incidence. A bull with no health issues, particularly bovine respiratory disease (BRD), is money in your pocket because it's the most costly disease complex to the cattle industry.
Ranking the traits
A recent analysis by Alison Van Eenennaam of the University of California, Davis and Mike MacNeil of the USDA Agricultural Research Service in Miles City, Montana, makes the case for disease-resistant breeding stock. They looked at the weighting that should be given to BRD resistance in a multiple-trait selection index for Angus terminal sires.
Their analysis showed that to maximize the profitability of the retained ownership production system modeled in the study, BRD incidence should be very heavily emphasized in terminal sire selection. It would be followed by a relatively uniform emphasis on weaning weight, postweaning average daily gain, and feed intake. Van Eenennaam shared the analysis at the Cattlemen's College during the 2012 Cattle Industry Convention.
Her analysis compared all of the above characteristics on a relative basis to the ability to select animals for carcass yield grade. Here's how they ranked by relative importance to yield grade.
● Marbling: 2.6 times more valuable
● Average Daily Gain: 3.7 times more valuable
● Feed Intake: 4.6 times more valuable
● Weaning Weight: 5.7 times more valuable
● BRD Incidence: 37.7 times more valuable
These comparisons suggest that using genetics to decrease the incidence of BRD is five times more valuable, economically, than selecting for weaning weight.
Decreased 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 those, a 13% reduction in average daily gain because of BRD, and a cost to diagnose and treat a BRD calf at $44.
The problem is we don't have good ways of selecting bulls or other animals on the basis of disease resistance. We have expected progeny differences (EPDs) and some DNA tests for weaning weights and other traits. There are none for disease resistance.
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.