Beef Genetics in the Dairy Management System: Effects of Maternal Genetics and Calf Management System

Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. Although the use of beef genetics improves calf value, variability has been reported in beef × dairy calf phenotype for traits related to muscularity and carcass composition. The objectives of this research were 1) to evaluate the calfhood growth, feedlot performance, carcass characteristics, and strip loin attributes of beef, beef × dairy, and dairy cattle and 2) to test the effect of the dairy management system compared to the beef management system on calves of all-beef genetics. Tested treatment groups included all-beef calves reared on range (A×B), all-beef calves born to Holstein (H ET) and Jersey (J ET) dams, Angus × Holstein crossbreds (A×H), and Angus × Jersey crossbreds (A×J). A total of N = 87 calves were tested for calfhood growth from birth to approximately 196 d of age. Straightbred Holstein steers (H) were added for the finishing trial in which N = 92 cattle were evaluated. For the finishing trial, cattle were grown to BW of 302 ± 29.9 kg for trial initiation and then fed 196 ± 3.4 d. Individual intake was recorded from d 28 to shipment for harvest. During the finishing phase, a subset of N = 43 steers was selected for repeated serum collection and longissimus thoracis muscle biopsy. After harvest, N = 78 strip loins were evaluated. At birth, A×J calves weighed the least (P < 0.01), and at 150 days of age, body weight was greatest among A×B calves (P < 0.05). Morphometric differences were detected between treatments (MANOVA P < 0.01). When BW was approximately 136 kg, A×B calves had greater top width and lesser hip height than A×J or A×H calves (ANOVA P < 0.01; standardized loadings of -0.48, and 0.63, respectively). During the finishing period, skeletal size measured as hip height, hip width, and body length was greatest for H cattle (P < 0.05). Cattle of all-beef genetics—A×B, H ET and J ET—and A×H had similar final shrunk BW and dry matter intake (P > 0.05). Additionally, meal frequency, meal length, eating rate, and time between meals was similar for cattle of all-beef genetics (P > 0.05). A strong relationship was observed between liver size and dry matter intake (r = 0.73, P < 0.01). Meal-to-meal variability of meal size was greatest for H cattle and least for beef-type cattle (P < 0.05). When adjusted for percentage of adjusted final body weight, feed efficiency was poorest for H (P < 0.05). Among Angus-sired treatments, no difference was observed in marbling score (P > 0.05). No difference was observed in ribeye area between all treatments (P = 0.58), and no difference was observed in muscle fiber area from the longissimus thoracis across the finishing period (P = 0.80). However, H cattle had a more oxidative muscle phenotype than beef-type cattle and lesser L*, a*, and b* values (P < 0.05). Compared to Angus-sired cattle, H cattle had the smallest area of longissimus lumborum in the posterior strip loin, greatest length-to-width ratio of longissimus lumborum in the posterior strip loin, and least round circumference relative to round length (P < 0.05). The dairy management system limited growth of beef genetics during calfhood, but feedlot performance, eating behavior traits, and carcass traits were unaffected by calf management system. Angus genetics transmitted greater muscularity and more moderate mature size than Holstein genetics, and maternal Jersey genetics provided less growth potential than maternal Holstein genetics.