Beef embryos in dairy cows: feedlot performance, mechanistic responses, and carcass characteristics of straightbred Holstein calves and Angus-sired calves from Holstein, Jersey, or crossbred beef dams

Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to test the feedlot performance of straightbred beef calves raised on a calf ranch and to compare finishing growth performance, carcass characteristics, and mechanistic responses relative to beef x dairy crossbreds and straightbred beef cattle raised in a traditional beef cow/calf system. Tested treatment groups included straightbred beef steers and heifers reared on range (A x B; n = 14), straightbred beef steers and heifers born following embryo transfer to Holstein dams (H ET; n = 15) and Jersey dams (J ET; n = 16) The finishing trial began when cattle weighed 301 & PLUSMN; 32.0 kg and concluded after 195 & PLUSMN; 1.4 d. Individual intake was recorded from day 28 until shipment for slaughter. All cattle were weighed every 28 d; serum was collected from a subset of steers every 56 d. Cattle of straightbred beef genetics (A x B, H ET, and J ET) and A x H were similar in final shrunk body weight, dry matter intake, and carcass weight (P > 0.05 for each variable). Compared with A x J cattle, J ET was 42 d younger at slaughter with 42 kg more carcass weight (P < 0.05 for both variables). No difference was observed in longissimus muscle area between all treatments (P = 0.40). Fat thickness was greatest for straightbred beef cattle, least for A x J cattle, and intermediate for A x H cattle (P < 0.05). When adjusted for percentage of adjusted final body weight, feed efficiency was greater for straightbred beef cattle compared with beef x dairy crossbred cattle (P = 0.04). A treatment x day interaction was observed for circulating insulin-like growth factor I (IGF-I; P < 0.01); 112 d after being implanted, beef x dairy crossbred cattle had greater circulating IGF-I concentration than cattle of straightbred beef genetics (P < 0.05). Straightbred beef calves born to Jersey cows had more efficient feedlot and carcass performance than A x J crossbreds. Calves of straightbred beef genetics raised traditionally or in a calf ranch performed similarly in the feedlot. Since Jersey maternal genetics offer less value than maternal Holstein genetics for beef x dairy crossbreeding programs, straightbred beef embryos can be used in Jersey cows to improve feedlot and carcass performance of resulting calves. Lay Summary Improved reproductive management has allowed dairy cow pregnancies to be optimized for beef production. The objectives of this study were to use an embryo transfer model 1) to investigate the effect of the dairy management system on beef genetics and 2) to directly compare the merit of Holstein and Jersey genetics for feedlot and carcass performance with modern beef genetics. Feedlot and carcass performance of straightbred beef cattle were similar regardless if the calf was raised in the traditional beef cow/calf system or if the calf was raised at a calf ranch. Based on greater daily live gain and carcass weight, Holstein maternal genetics had greater terminal merit than Jersey maternal genetics. Regardless of dam breed, dairy genetics increased carcass leanness. Minimal differences were detected between adjusted feed efficiency of beef and beef x dairy cattle, but underestimation of mature size of beef x dairy could have overestimated efficiency. Genetic differences were more impactful than differences between the conventional beef and dairy calfhood management systems on feedlot and carcass performance.