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Estimates of Repeatability and Heritability of Horn Fly Resistance in Beef Cattle

Estimates of Repeatability and Heritability of Horn Fly Resistance in Beef Cattle,A. H. Brown,C. D. Steelmant,Z. B. Johnson,C. F. Rosenkrans,T. M. Bra

Estimates of Repeatability and Heritability of Horn Fly Resistance in Beef Cattle   (Citations: 6)
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Horn fly population density on 215 beef cows representing seven breed groups and 51 sires was used to obtain estimates of repeatability (rm) and heritability (h21 for resistance to the horn fly (Haematobia irritans IL.1 Diptera: Muscidae). Total horn fly densities were determined weekly on each cow beginning in May and ending in late October or early November of 1988, 1989, and 1990. No insecticides were used on cattle in this study. Estimates of h2 for horn fly resistance (low horn fly number per cow) were obtained by the paternal half-sib method (44) and as twice the intrasire regression of offspring on dam (~~DD/s). Variance component estimates were obtained using a com- pletely nested ANOVA that included overall mean, breed, sire/breed, cow/sire, and residual error. One hundred twenty-six daughter-dam pairs were available for regression analysis. In a prelim- inary analysis, the within-breed regression was nonsignificant IP > .05), implying that the regres- sion was the same for all breeds; therefore, breed was deleted from the model. The regression model included an overall mean, year, and the intrasire regression of daughter on dam (~DD/s). The esti- mate of rn was .47 f .02. Estimates of h2 were .78 k .16 and .59 k .10 from the 44 and ~~DD/S methods, respectively. Similar estimates of rm and h2 were obtained when each observation of horn fly number per cow (XI was transformed to both loglo (XI and dx. These estimates suggest the possibility of selection procedures as an environ- mentally safe alternative to the use of chemical control.
Published in 2010.
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