PSIV-A-2 - Beef Genetics in the Dairy Management System: Management System and Maternal Genetic Effects on Calf Growth and Body Measurements

Abstract: Improved reproductive management allowed dairy cow pregnancies to be optimized for beef production. The objective of this sire-controlled study was to characterize effects of maternal genetics and the dairy management system on calf growth. Pregnancies were created with a 2 × 2 factorial arrangement of dam breed (Holstein or Jersey) and mating type (artificial insemination or implantation of an in vitro produced embryo from a commercial beef cow oocyte). Resulting calves were reared in a calf ranch. Additionally, commercial beef cows were inseminated and reared resulting calves on range. Therefore, the five treatments were Angus × Holstein (A×H; n = 19), Angus × Jersey (A×J; n = 22), Angus × Beef gestated by Holstein (H-ET; n = 18), Angus × Beef gestated by Jersey (J-ET; n = 8), and Angus × Beef raised by beef (A×B; n = 20). Beginning at birth, calf body weight, cannon circumference, forearm circumference, top width, hip width, and hip height were measured approximately every 28 days until approximately 196 days of age. At birth, A×J calves weighed the least (P < 0.01). At 150 days of age, body weight was greatest (P < 0.05) among A×B calves, intermediate among H-ET and A×H calves, and least among J-ET and A×J calves (P < 0.05). Morphometric differences were detected between treatments (MANOVA P < 0.01). Primary discriminant function scores identified A×B calves having lesser values than A×J or A×H calves (ANOVA P < 0.01); A×B calves had greater cannon circumference, greater top width, and less hip height (standardized loadings of -0.47, -0.48, and 0.63, respectively). The dairy management system limited growth rate of beef genetics compared to the beef management system. In addition, Holstein dams transmitted greater growth potential than Jersey dams. Replacing maternal dairy genetics with beef genetics increased top width and decreased hip height.