Nutrient demand increases as a direct response to blood loss. When the blood-feeding fly population is significant enough to cause the cow’s body to divert nutrients into replacing lost blood, milk production may suffer.
Flies transmit diseases including anthrax, brucellosis and tuberculosis, as well as Staphylococcus and Streptococcus mastitis infections.
On average 1 adult cow can produce up to 148 lbs of manure providing a perfect breeding ground for flies.
Horn flies take up to 40 blood meals per day causing irritation and affecting cattle comfort.
Horn flies are a known vector for the bacteria that causes beef mastitis, a disease that could have a direct effect on calf weaning weights.
The economic losses from horn flies can be attributed to reduced weight gains, decreased feed efficiency caused by loss of blood and excessive energy expenditure to dislodge the flies.
Biting flies play a key role in the development of “summer sores”- non-healing skin lesions, characterized by intense itching and the formation of exuberant granulation tissue (proud flesh).
Stable flies will feed on blood from horses and practically any warm blooded animal including humans, pets and other livestock. Their bites are very painful and can send a horse into a frenzy.
Horn flies feed on the shoulders, neck, withers and abdomen of horses. Horn flies often feed on the ventral midline and can be a cause of midline dermatitis - an inflammation of the skin characterized by extreme itching and irritation.
Fly impact on feedlot profitability can be measured within an economic threshold defined as the level of flies in which the economic loss is equal to the cost of controlling.
The economic injury level for feeder cattle is when the stable fly population reaches an average of about five flies per front leg.
The economic threshold of just five flies per animal showed a reduction in feed efficiency that resulted in an average loss of $8.51 per animal per season.
The common house fly, which is worldwide in distribution, is by far the greatest problem in farrowing and weaning houses.
Major outbreaks of greasy pig and coccidiosis can be maintained by very high fly populations.
When sows are sick with mastitis, flies are attracted to the udder and skin surfaces in great numbers and they can be responsible for enhancing severe outbreaks.