Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: June 11, 2010
Publication Date: July 12, 2010
Citation: Chase, C.C., Gasbarre, L.C., Coleman, S.W., Riley, D.G., Connor, E.E. 2010. Gastrointestinal nematode egg shedding rates in temperate adapted Angus and tropically-adapted Brahman and Romosinuano calves at weaning . Journal of Animal Science 88(2), E-Suppl. Technical Abstract: Gastrointestinal nematode egg shedding rates were determined at weaning for three years in temperate adapted Bos taurus (Angus, n = 107), tropically-adapted Bos taurus (Romosinuano, n = 126), and tropically-adapted Bos indicus (Brahman, n = 87) calves in the subtropics (Florida). Each year, fecal samples were obtained from purebred calves on the day of weaning and the next day. Purebred calves were born and raised at two locations (i.e., two farms) until after weaning. Eggs per gram of feces were determined for each calf each day and the average of the two days was analyzed. The Proc Mixed procedure of SAS was used for statistical analyses and the model included the effects of location, year, breed, sex, and interactions. Location (P < 0.10), year (P < 0.05), breed (P < 0.003), and sex (P < 0.10) affected average eggs per gram of feces. Angus had the highest average eggs per gram of feces (179 ± 22.6); Brahman had the lowest average eggs per gram of feces (88 ± 24.0); and Romosinuano had intermediate eggs per gram of feces (compared to Angus and Brahman; 149 ± 21.6). There was however, a three way interaction among year by breed by sex (P < 0.02). Analysis by year indicated that although average eggs per gram of feces was consistently ranked from Angus > Romosinuano > Brahman over the three years, that only in year 2 was breed and breed by sex significant. Breed by sex (P < 0.01) in year 2 was due to extremely low average eggs per gram of feces in both male and female Brahman (25 ± 45.4 and 58 ± 48.4) compared to both Angus (183 ± 45.4 and 195 ± 48.4) and Romosinuano (245 ± 36.0 and 39 ± 37.4). In the subtropics, tropically-adapted Bos taurus (Romosinuano) and tropically-adapted Bos indicus (Brahman) in particular appear to offer some resistance to gastrointestinal nematodes compared to temperate adapted Bos taurus (Angus).