Hair and infestation by horn flies, haematobia irritans, in black and white holstein cows

Gunta Gutmanis; Cecília José Veríssimo; Luciana Morita Katiki; Luciandra Macedo de Toledo; Mariana Santos de Miranda; Leandro Rodrigues; Ana Carolina Peroni Gomes

Hair and infestation by horn flies, haematobia irritans, in black and white holstein cows

2017

The horn fly (Haematobia irritans), since its introduction in Brazil in the 1980s, has caused significant loses to cattle production. The damage caused to the animal because it stops feeding due to the irritation caused by the flies is much greater than that caused by the blood loss. When lying on the host, they are almost always upside down with their wings partially open. There are reports about several bovine breeds indicating that dark coats attract more flies than lighter ones. There are several hypotheses to explain why some animals have more flies than others. Possibly, this preference is caused by the size and increased activity of the sebaceous glands or concentration of testosterone, or by the heat irradiated. The objective of this work was to relate the number of horn flies on black and white Holstein animals with their coatâ€™s predominant color. Forty-nine cows of that breed from the Institute of Zootechnics, located in Nova Odessa, SP, between 1 and 8 years old, were classified as having light (N = 19) or dark (N = 30) coat according to white or black preponderance. The number of horn flies was counted on the right side of the animals on September 20, 2016. The animals were from the same grazing area. The mean horn fly number on cows considered dark was higher (38 Â± 7, P <0.05) than the number on cows with higher percentage of white hair (13 Â± 2), confirming that this fly species has a predilection to parasitize dark animals, also in the case of black and white Holstein.

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