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Title: GENOTYPE X ENVIRONMENT INTERACTIONS IN ANGUS, BRAHMAN, AND RECIPROCAL- CROSS COWS AND THEIR CLAVES GRAZING ENDOPHYTE-INFECTED TALL FESCUE, COMMON BERMUDAGRASS, OR BOTH FORAGES

Author
item Brown, Michael
item BROWN JR, A - UNIV OF AR, FAYETTEVILLE
item Rainosek, Perry
item Miesner, James

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2000
Publication Date: 7/1/2000
Citation: BROWN, M.A., BROWN JR, A.H., JACKSON, W.G., MIESNER, J.R. GENOTYPE X ENVIRONMENT INTERACTIONS IN ANGUS, BRAHMAN, AND RECIPROCAL-CROSS COWS AND THEIR CLAVES GRAZING ENDOPHYTE-INFECTED TALL FESCUE, COMMON BERMUDAGRASS, OR BOTH FORAGES. JOURNAL OF ANIMAL SCIENCE SUPPLEMENT. 2000. v.78(Suppl.):Abstract p. 75.

Interpretive Summary: Abstract Only.

Technical Abstract: Approximately 190 Angus (AA), Brahman (BB), and reciprocal-cross cows (AxB and BxA) and their 434 calves born in 1995-1997 were used to evaluate the effect of forage management system on reproductive and preweaning performance. Cows were managed on 16 ha pastures of either common bermudagrass (BG), endophyte-infected tall fescue (E+), or E+ in the fall and spring and BG in the summer (ROT) with all breed types represented in each pasture. Calves were born February through May, weighed at birth and tagged; bull calves were castrated at birth. Calves were weaned at an average age of 205 days when full weights and hip heights were taken. Maternal heterosis in 205-d weight was larger on E+ than BG (32.0 kg vs 20.4 kg, P<.10) with maternal heterosis on ROT (29.2 kg) not significantly different from the other two forages. Maternal heterosis in weaning hip height was similar for E+ and ROT (4.7 cm and 4.3 cm) and both exceeded (P<.01) BG (1.4 cm). Heterosis in calving percentage was larger (P<.05) on E+ (29.6%) compared to BG and ROT (9.5 and 2.6%). Similarly, heterosis in 205-d weight per cow exposed was larger (P<.01) on E+ (114.3 kg) than BG or ROT (36.4 and 39.7 kg). Empirical reasons for these interactions might be suggested by the larger effect of E+ on the Angus and their calves compared to the other cow breed groups and their calves for calf performance and the larger effect of E+ on purebred cows compared to crossbred for reproductive performance. These data suggest a higher level of stability in calf performance, comparing BG and E+, for the average of calves from crossbred cows compared to the average of calves from purebred cows. Similarly, these data suggest a higher level of stability in cow reproductive performance across forages in crossbred cows compared to purebred cows.