Morphological growth and carcass performance of crossbred beef × dairy cattle with expression of beef- versus...

Considerable variance in the expression of beef- versus dairy-type among contemporary groups of beef × dairy cattle may contribute to management challenges and financial losses. The objective of this study was to evaluate influence of beef- versus dairy-phenotype expression on growth metrics through the finishing phase and carcass performance. Angus × Holstein or SimAngus × Holstein steers and heifers were managed within 9 contemporary groups through the finishing period and classified at harvest based on frame score and muscling score equally into 1 of 4 phenotype groups (n = 82 to 84 cattle per group): (i) fully dairy-type, (ii) partially dairy-type, (iii) partially beef-type, and (iv) fully beef-type. Linear body measurements, carcass ultrasound data, and visual frame and muscling scores were obtained on arrival at the finishing yard and on re-implant. Carcass data were obtained after slaughter. Data were analyzed for effect of phenotype group and its interaction with time during the finishing period. Measurements were compared for their contribution in predicting harvest phenotype outcome. Body weight was not different (P = 0.64) between groups, indicating that differences (P < 0.05) in muscling and frame scores were not attributable to weight. Fully dairy-type crossbreds had greater (P < 0.05) hip height, shoulder height, and body depth than fully beef-type crossbreds at both processing times. Fully beef-type crossbreds had greater (P < 0.05) ultrasound 12^th rib fat thickness and ultrasound ribeye area than fully dairy-type crossbreds at arrival and re-implant. However, ribeye area at harvest was not different (P = 0.32) between phenotype groups, although round muscling score differed (P < 0.01) and generally decreased from fully beef-type to fully dairy-type. Ribeye area at harvest was weakly correlated with live animal muscling score (r = 0.15) and round muscling score (r = 0.22), whereas live animal muscling was much more highly correlated (r = 0.53) with round muscling. Round muscling was the most indicative of phenotype classification at harvest. Hence, ribeye area at harvest may not be entirely representative of visual phenotype differences in muscling of beef × dairy crossbreds. Longitudinal measurements of carcass traits and frame size may serve as effective sortation tools in minimizing phenotypic variation of beef- and dairy-type among beef × dairy cattle.