Bovine Leukemia Virus

The Hidden Cost of Bovine Leukemia Virus on Dairy Cows

Lack of precise information regarding the costs of reduced milk production and cow longevity has discouraged researchers from making rough estimate of the total cost of BLV infection. However, a rough estimate may be better than no estimate at all, and lack of an estimate does not mean that the estimate is $0.

The MSU BLV team has received M-AAA funding to develop a partial budget tool that producers can use to estimate what BLV is costs as well as economic benefits of reducing BLV prevalence in their herd. This is expected to be released in 2023. 

What is a Partial Budget?

Economists call it a “Partial Budget” when you estimate total economic impact by adding up various cost components.

Milk Production

The USDA 1996 dairy study determined that 25.322 (115 kg) of milk (per cow/year) was lost for each 10 percent increase in BLV-infected cows within a herd (32). Our recent Michigan study found nearly identical herd-level production losses as did this NAHMS study (5). We estimated that 25.322 lbs (11.5 kg) of rolling herd average milk was lost for every 1% increase in BLV herd prevalence. 

Cost of Tumors

BLV-associated tumors are now the most common reason that USDA condemns cattle (10). Depending on the terms of the sale, the producer may or may not lose the full slaughter value of the animal if it is condemned at slaughter.

Cow Longevity

The estimate of reduced survival of ELISA-positive cows as compared with their negative herdmates was based on a 2010-2012 study of 3,849 cows in 112 Michigan herds in which cows were followed for an average of 597 days (6). BLV-positive cows were 23% more likely to be culled than were BLV-negative cows. We attempted to estimate the economic loss when an average milking cow turns into an average cull cow. The average sale price for a cull cow can usually be recalled by most producers. Estimating the value of the average milking animal is more difficult since there is generally not a big market for such animals. The best approach may be to think of the lowest price you would accept to sell an average milking-aged cow from your herd.

Other Costs

You can include in your analysis any additional costs for BLV testing, single-use needles and sleeves, loss of export markets, colostrum handling, fly control, isolation pens for BLV-positives or any other extra costs incurred to prevent or control BLV (56).