Identification of Sindhi cows that are susceptible or resistant to Haematobia irritans

Abstract

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.

Global genomic methylation related to the degree of parasitism in cattle

“…For the infestation by H. irritans , heifers were classified into only two categories (resistant or resilient) (Table 1 ), differing from the distribution using two clustering methods—descriptive analysis and best linear unbiased predictions (BLUPs)—and reported that the former identified 16% and 10.7% of the animals as resistant and susceptible, respectively, whereas the latter clustered 12% of the animals as resistant and 12% as susceptible 29 .…”