Author(s): MEDEIROS, M. A. de; BARROS, A. T. M. de; RIET-CORREA, F.; MARQUES, A. R.; LOPES, J. R. G.; VIEIRA, V. D.; MIRABALLES, C.

Summary: To identify susceptible and resistant Haematobia irritans cows, horn flies were counted biweekly for 3 years in a herd of 25 Sindhi cows. Repeated measures linear mixed models were created including cow as a random factor. The results were analyzed by: 1) observing horn fly counts, considering fly-susceptible cows with infestations appearing in the upper quartile more than 50% of the weeks and in the lower quartile less than 20% of the weeks, and fly-resistant cows those that the number of flies was in the lower quartile more than 50% of the weeks and in the upper quartile less than 20%; 2) by the best linear unbiased predictions (BLUPs), to evaluate the cow effect on fly counts. Fly-susceptible cows were those in which the infestation appeared in the 90th percentile of the BLUPs, whereas fly-resistant cows appeared in the 10th percentile. For the observational method the individuals identified as resistant varied between 8% and 20% and 8% to 12% were susceptible. For the BLUP method, the rates of susceptible and resistant cows were 12%. The agreement among methods suggests that susceptible cows can be identified by observations of fly counts, allowing for selective breeding, culling or treatment.

Publication year: 2019

Types of publication: Journal article

Unit: Embrapa Beef Cattle

Keywords: Animal selection, Bovines, Bovino, Controle Integrado, Horn fly, Integrated control, Mosca dos Chifres, Seleção animal