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Title: Residual feed intake and temperament breed differences among Florida heifers.

Author
item Riley, David
item HANSEN, G. - UNIVERSITY OF FLORIDA
item Coleman, Samuel
item Chase, Chadwick - Chad

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 4/2/2007
Publication Date: 7/8/2007
Citation: Riley, D.G., Hansen, G.R., Coleman, S.W., Chase, C.C. 2007. Residual feed intake and temperament breed differences among Florida heifers. Journal of Animal Science Supplement. Southern Association of Agricultural Scientists. Journal of Animal Science Supplement. 85(1):Paper No.T71.

Interpretive Summary:

Technical Abstract: The objective of this work was to evaluate residual feed intake, average daily gain, chute temperament score, and exit velocity of Brahman (B),Angus (A), and Romosinuano (R) (n = 40, 19, and 26, respectively)and F1 (n = 7, 8, and 12 for BA, RA, and RB, respectively) heifers. One month after weaning in September 2006, heifers were transported 485km to the Florida panhandle. Heifers were placed in feeding pens and acclimated to a corn-based diet for 3 wk. Subsequently, they completed a 70-d intake test. Body weight, chute temperament score (from 1 to 5; higher scores indicated more nervous behavior), and exit velocity (m/s) were recorded weekly. Body weight and feed consumption records were used to generate residual feed intake values (RFI). Average daily gain and feed conversion ratio (FCR) were calculated. Pen (n = 6), breed (n = 6; 3 purebred and 3 crossbred groups), and age of dam were fixed effects. Age in days at test start was included as a covariate. Bodyweight was a covariate in analyses of chute score and exit velocity. Records were placed in 3 RFI groups: high, medium (mean ± 0.5SD), and low values, and this term was modeled as a fixed effect in additional analyses. Sire was a random effect. Brahman heifers had more favorable (P < 0.05) RFI (–1.08 ± 0.25 kg) than other groups which ranged from 0.06 ± 0.17 (R) to 0.46 ± 0.2 kg (A). Brahman ADG (0.84 ± 0.06 kg) was less than (P < 0.05) that of Angus heifers (1.06 ± 0.05 kg). Means for ADG of crossbred heifers were 0.86 ± 0.08(RB), 1.08 ± 0.1 kg (BA), and 1.1 ± 0.09 kg (RA). No breed effect was detected for FCR (P = 0.31). Brahman and Brahman-cross heifers had the largest exit velocity means (range from 2.89 ± 0.15 for RB to 3.43± 0.19 m/s for BA); these were larger (P < 0.05) than Angus (2.22± 0.12 m/s) and Romosinuano (2.12 ± 0.1 m/s). Chute temperament score means for Angus (2.38 ± 0.1) and RA (1.9 ± 0.26) were lower (P < 0.05) than those of all other breed groups. Groups for RFI did not explain variation in analyses of temperament traits (P > 0.29).