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Title: VARYING DIFFERENCES BETWEEN SEXES IN BIRTH WEIGHT AND WEANING WEIGHT OF CALVES SIRED BY TROPICALLY ADAPTED BREEDS AT SIX DIVERSE U.S. LOCATIONS.

Author
item HERRING, A - TEXAS A&M UNIVERSITY
item CUNNINGHAM, S - TEXAS A&M UNIVERSITY
item Cundiff, Larry
item Chase, Chadwick - Chad
item SANDERS, J - TEXAS A&M UNIVERSITY
item Phillips, William
item BAKER, J - UNIVERSITY OF GEORGIA
item HOLLOWAY, J - TEXAS AG EXP. STATION
item WARRINGTON, B - TEXAS AG EXP. STATION
item Coleman, Samuel

Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 1/4/2005
Publication Date: 2/4/2005
Citation: Herring, A.D., Cunningham, S.F., Cundiff, L.V., Chase, C.C., Sanders, J.O., Phillips, W.A., Baker, J.F., Holloway, J.W., Warrington, B.G., Coleman, S.W. 2005. Varying differences between sexes in birth weight and weaning weight of calves sired by tropically adapted breeds at six diverse U.S. locations [abstract]. American Society of Animal Science Southern Section Meeting. Paper No. 116. p. 30.

Interpretive Summary:

Technical Abstract: In the early 1990s, a joint effort to evaluate several tropically adapted breeds through production of F1 calves was initiated at Brooksville, FL, Clay Center, NE, El Reno, OK, McGregor, TX, Tifton, GA, and Uvalde, TX. Sire breeds (at number of locations) evaluated were Brahman (Br; 6), Boran (Bo; 3), Tuli (Tu; 6), Senepol (Se; 2), Angus (An; 2) and Hereford (He; 2). Sires in each breed were used at multiple locations. Location was partly confounded with age of dam and breed type of dam. Records from first parity cows were excluded. Each location used An purebred and/or crossbred cows, but some locations used only purebred An or An and He cows or only crossbred cows. Only F1 calves from Bos taurus dams were included in this analysis. Weaning weights were adjusted to 205 d basis. Birth weight (BWT) and 205-d weaning weight (WWT) were analyzed through mixed model procedures in SAS. Fixed, independent variables were sire breed (SB), location (LOC), age of dam, birth year, calf sex (SEX), SB x LOC, SB x SEX, and SB x LOC x SEX. The regression on birth date (BDATE) within year-LOC combination was included for BWT and WWT, and sire nested within SB was included as a random effect. All independent effects except birth year accounted for significant variation in BWT and WWT. The regression on BDATE within year-LOC ranged from 0.10 kg/d to –0.01 kg/d for BWT and from 0.39 kg/d to –0.15 kg/d for 205-d WWT. Previous reports have found a SB x SEX interaction for BWT and WWT when Bos indicus (Bi) and Bos taurus (Bt) sires are bred to Bt dams where males are much heavier than females when sired by Bi vs Bt breeds. This same trend is documented here across locations. The SEX difference in BWT (kg) across LOC-SB combinations ranged from 3.5 to 7.5 for Br, 2.2 to 6.0 for Bo, 2.3 to 6.4 for Tu, 1.9 to 2.4 for Se, 2.7 to 3. 4for He, and 3.5 to 4.7 for An. The SEX difference in 205-d WWT (kg) across LOC-SB combinations ranged from 8.3 to 27.9 for Br, 9.0 to 19.1 for Bo, 6.4 to 37.8 for Tu, 1.1 to 15.9 for Se, 1.7 to 10.7 for He, and 18.5 to 27.9 for An.