Growth and reproductive performances in F1 crossbred heifers from Hereford, Braford, and Bonsmara sires and Angus and Brangus dams12

The objective of this research was to evaluate source and extent of tropical adaptation affecting heifer BW and productivity traits. The F1 heifers with Brangus (BN) dams were sired by Braford (BFBN; n = 44), Hereford (HEBN; n = 29), and Bonsmara (BOBN; n = 58) sires. The F1 heifers with Angus (AN) dams were sired by Hereford (HEAN; n = 32) and Bonsmara (BOAN, n = 40) sires. The F1 heifer breeds did not differ (P > 0.22) for pregnancy and weaning rate. Calving rate was similar (P > 0.26) among F1 heifer breed types, but there was a tendency (P < 0.10) for calving rate to be greater for HEBN compared with BOBN F1 heifers. Live BW at weaning of their first calf was similar (P > 0.17) for BFBN and HEBN F1 cows and for HEBN and BOBN F1 cows but was greater (P < 0.05) for BFBN compared with BOBN and for BOAN compared with HEAN. The F1 cows with BN dams were heavier (P < 0.01) and had lower (P < 0.05) BCS at weaning than F1 cows with AN dams. Calf adjusted 205-d BW was similar (P > 0.25) among BFBN, HEBN, and BOBN F1 cows but was greater (P < 0.01) for BOAN compared with HEAN and for BN compared with AN granddams. In the present study, there were differences in heifer BW and offspring growth traits among F1 breed types, but there was not a distinct overall advantage (P > 0.35) of any particular breed type based on calf:dam weaning BW ratios.