The horn fly has a direct role in the initiation and spread of staphylococcal mastitis among dairy heifers, but this insect vector can be successfully managed.

Effective fly control means healthier dairy cattle, along with optimum milk production. (Photo by Bob Nichols, USDA Natural Resources Conservation Service)
Effective fly control means healthier dairy cattle, along with optimum milk production. (Photo by Bob Nichols, USDA Natural Resources Conservation Service)

In turn, this benefits animal health and well-being—as well as producer profits.

As reported in the Journal of Animal Science, the horn fly is an irritant to livestock, and in response to the incessant painful biting, blood sucking and stress, cattle expend a great deal of energy in defensive behavior.

This results in elevated heart and respiratory rates, reduced grazing time, decreased feeding efficiency and rate of gain, as well as reduced milk production.

Additionally, the horn fly (Haematobia irritans) can serve as a disease vector, such as in the initiation and spread of mastitis in dairy heifers.

As such, it is one of the most economically important pests of cattle worldwide. In the U.S. alone, $700 million to $1 billion in losses are attributed to the horn fly each year, while an additional $60 million is spent annually on parasite control.

Herd surveys have revealed that the prevalence of mastitis in heifers is markedly lower in dairy herds using some form of fly control compared with herds without a pest-control program.

The horn fly has a demonstrated role in the development of teat lesions on heifers that develop into chronic Staphylococcus aureus mastitis, which is then spread among heifers by these same insect vectors.

Such infections, if left untreated, negatively affect the development of milk-producing tissues in the udder, resulting in less than optimal yield and quality during the first and subsequent lactations.

The implementation of horn fly-control measures such as aerosols, bait, strips, foggers, dust bags, traps, oilers, ear tags, pour-ons, natural predators and insect-growth regulators is instrumental in reducing the new-infection rate, while existing mastitis cases can be eliminated with antibiotic therapy.

Such management practices will promote animal health and well-being, as well as ensure that heifers calve with low somatic cell counts and the potential for maximum milk yield, thereby enhancing producer profits.

This abstract appeared in volume 94 of the Journal of Animal Science and is being reprinted with permission. For more information: doi:10.2527/jam2016-0059