Numerous studies have tried to nail down the cost of bovine respiratory disease (BRD) in dairy replacements, and the number they come up with are as varied as the studies themselves.
The reason is that the studies typically measure different time periods, such as birth to weaning, birth all the way to calving, and estimates averaged per cow. Compounding the problem is that record keeping varies farm to farm, and a mild case of BRD may be missed and not recorded.
To try to get a handle on the issue, Elanco Animal Health technical consultants looked at herd health records from 23 U.S. dairies that appeared to record herd health information consistently over several years, says Kevin Dhuyvetter, an economist and technical consultant with Elanco.
Using two years of herd records, the study involved 104,100 dairy heifers and looked at the first 120 days of life. The heifers in the study were primarily Holsteins. The average incidence rate of BRD was 37.2 percent of heifers, but ranged from 7 to 68 percent across the herds, says Dhuyvetter. “Most of the disease occurred in the first 120 days of a calf’s life,” he says. And if heifers were infected, they averaged 1.7 cases.
The consequences of BRD infection are multiple: decreased dry matter intake and rate of gain, treatment costs and extra labor, higher culler and mortality risk, delay in time to first service and calving and lower production in first lactation.
Dhuyvetter cited a sutdy where 27 percent of BRD-infected calves in the study failed to calve by 25 months. That’s 10 percentage points more than uninfected calves. “The median age at first calving was 12 days longer for heifers with BRD,” he says. “If calves are growing slower, they are likely being bred later.”
Other studies have shown that most of the slower growth comes early in life, and infected heifers can have growth rates equal to uninfected heifers at a year of age. But the infected heifers are behind in their first year, when feed costs are typically highest. And since they are growing slower, they are bred later and calve later.
When Dhuyvetter placed all this data into an economic model, he calculated the cost per day of life to be 20₵ higher for BRD-infected heifers. Over the life of the heifer from birth to calving, that translated to a $250 cost per BRD-infected heifer. The cost to raise and calve an uninfected heifer was estimated to be $2,194. Those to raise and calve an infected heifer was $2,445.
Based on previous research, it was estimated that the infected heifers also produced 270 pounds less milk in their first lactation. So that tacked on another $29 loss from lower income over feed cost for a BRD infection, bringing the total cost of BRD infection to $279.
So the question then becomes whether cow vaccination and early calfhood vaccination is worth it in your herd. Cow vaccinations might run from $3 to $5 dollars, depending on the vaccine used and the amount of milk loss that occurs the day or two after vaccination. There is also a labor cost to administering the vaccine, says Mark Armfelt, a veterinarian and technical consultant with Elanco.
Whether you vaccinate boils down to BRD incidence in your herd. And that’s where records are key: How prevalent is BRD in your herd? Do you have multiple cases per animal? Are these heifers slower growing? Are they culled more frequently? And do they enter the milking string later?