Influence of breed composition of developing heifers on growth performance and temperament in pasture-based systems

The objective of this five-year study was to evaluate how breed composition affects growth performance and temperament of beef heifers developed in a forage-based system. Three hundred and seventy beef heifers [initial body weight (BW) = 262 ± 98.2 kg, age = 8.3 ± 1.6 months] were sorted into five major breed compositions: English, Bos taurus-influenced, Bos indicus-influenced, Continental and Japanese. Heifer full BW and hip height were obtained on days 0, 56 (turnout) and 240 (end of the study). Temperament was assessed on day 0 and d 240 via exit velocity and pen score. At turnout and study completion, BW differed (P = 0.001), with Continental and Bos taurus–influenced heifers heaviest, and English and Japanese lightest. Average daily gain was greatest in Continental and Bos taurus–influenced heifers and lowest in Japanese (P ≤ 0.04). A greater proportion of English and Bos taurus–influenced heifers reached ~65% of mature BW (P < 0.01). Bos indicus–influenced heifers exhibited more excitable temperament (P ≤ 0.04). Overall, Continental heifers showed greater growth, whereas English heifers exhibited more desirable temperament but lower performance; however, English and Bos taurus–influenced heifers exhibited a greater proportion of heifers reaching target percentages of mature BW.