Comparison of Pure and Crossbred Japanese Black Steers in Growth Performance and Metabolic Features from Birth to Slaughter at a Spanish Fattening Farm

SIMPLE SUMMARY: Cattle growth performance is a determinant of beef production. Nowadays, customers demand specialized, high-quality beef products produced according to stringent health and welfare standards. Intramuscular fat, or marbling, improves beef quality, and the Japanese Black (Wagyu) is the breed with the highest rates of marbling. Wagyu steers are reared under specific conditions in Japan, which may differ from the conditions in other countries, and these differences may affect animal well-being and, therefore, growth rates and beef quality. The current study shows that purebred Wagyu and crossbred Wagyu-by-Angus steers that were raised at a cow–calf operation and fattening system in Spain with no exercise restriction, high welfare, and a local diet high in olein content showed appropriate growth and fattening rates, health status, and metabolic development. Wagyu crossbred steers did not show substantially faster growth than purebred Wagyu animals, so they may not be as profitable as purebred Japanese Black in this type of production system. ABSTRACT: Japanese Black (Wagyu) cattle produce high-quality beef. However, whether Wagyu steers can be profitably raised under conditions different than the traditional Japanese ones remains unclear. From 2018 to 2020, we raised 262 Wagyu purebred steers, 103 Wagyu-by-Angus (Wangus) crossbred steers, and 43 Angus-by-European (ACL) crossbred steers on a Spanish farm with high welfare standards and a locally sourced, high-olein diet. Factors and factors’ interactions impacting steer growth were analyzed using generalized linear models. ACL steers grew faster than the other two groups, with Wangus showing intermediate fattening and muscle development. Average daily weight gains (kg/day) were 0.916 for Wagyu, 1.046 for Wangus, and 1.293 for ACL during the weaning to growing period, and 0.628 for Wagyu, 0.64 for Wangus, and 0.802 for ACL during the growing to fattening phase. ACL showed the lowest marbling rates. Wagyu and Wangus usually showed higher cholesterol, triglycerides, and high-density lipoprotein than ACL. ACL calves may experience greater stress at weaning, as suggested by higher glucose, lactate, and β-hydroxybutyrate than the other groups. The results suggest that Wagyu and Wangus steers showed adequate growth, health, and metabolic development in this type of production system, with Wagyu purebreds probably being more profitable than Wangus crossbreeds.