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The effects of selection for size in cattle on horn fly population density
Author(s) -
STEELMAN C. D.,
BROWN C. J.,
McNEW R. W.,
GBUR E. E.,
BROWN M. A.,
TOLLEY G.
Publication year - 1996
Publication title -
medical and veterinary entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 82
eISSN - 1365-2915
pISSN - 0269-283X
DOI - 10.1111/j.1365-2915.1996.tb00718.x
Subject(s) - haematobia irritans , withers , zoology , biology , french horn , population , herd , veterinary medicine , muscidae , body weight , ecology , stomoxys , medicine , psychology , pedagogy , demography , sociology , endocrinology
. Statistically significant differences were observed in the population density of the horn fly, Haematobia irritans irritans L., on Angus cows having significantly different frame sizes. Angus cows, averaging <112.5 cm in height at the hip, had significantly lower numbers of horn flies than Angus cows that measured 112.5–117.5 cm, 117.5–120 cm, 120–126 cm and >126 cm in height at the hip. The Angus I cows(126 cm). The estimated heritability (h 2 ) of horn fly resistance was 0.43 ± 0.07 and 0.95 ± 0.31 for 1989 and 1990, respectively. Horn fly counts on the Angus I herd (<112.5 cm in height) was 118.1 (probable breeding value, PBV = ‐20.69) to 165 horn flies per cow (PBV = 26.9 flies per cow in 1989) and from 75.9 (PBV = ‐29.1) to 134.5 (PBV = 29.5) flies per cow in 1990. Angus I bulls had PBV = ‐23.7 to 13.4 and from‐26.5 to 14.75 in 1989 and 1990, respectively. The Angus II cows had horn fly counts that ranged from 159.6 (PBV of‐23.5) to 208.1 (PBV of 25) per cow in 1989 and from 232.3 (PBV of‐56.2) to 378.7 (PBV of 90) per cow in 1990. Angus II bulls had PBVs that ranged from‐17.1 to 18.9 in 1989 and from ‐28.1 to 48.8 in 1990. The Angus I cows had significantly (P < 0.0001) lower numbers of hom flies (mean of 63.8 horn flies per m 2 ) than the small, medium or large Angus II cows (mean of 129.4, 149.6 and 145.5 hom flies per m 2 , respectively). The data indicated that some specific factor(s) associated with cow size contribute(s) to innate resistance of cattle to the horn fly.