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Genetic traits and β-casein A2 of Holstein and crossbred dairy cattle in an organic and low-input dairy herd.

B. J. Heins

Events

06-24-2020

Abstract:

328
Genetic traits and β-casein A2 of Holstein and crossbred dairy cattle in an organic and low-input dairy herd.
B. J. Heins*1, G. M. Pereira1, L. C. Hardie2, C. D. Dechow2. 1University of Minnesota Morris, MN, 2Pennsylvania State University State College, PA.

The University of Minnesota initiated a crossbreeding designed study in 2000. The study continues at the West Central Research and Outreach Center, Morris, Minnesota, and is currently part of the low-input sustainable and organic grazing dairy project. The 2 research herds are composed of 1964 genetic control Holsteins (HO), contemporary HO, ProCROSS composed of Montb�liarde, Viking Red, and HO breeds and GrazeCross cattle composed of Jersey, Normande, and Viking Red breeds. Control HO (n = 107), ProCROSS (n = 385), GrazeCross (n = 233), were compared with contemporary HO (n = 224) for genetic traits and Beta Casein A2 status from genomic testing. Four hundred and seventy animals were genotyped with the GGP Bovine 50K and 295 animals with the GGP Bovine 150K from Neogen Genomics (Lincoln, NE) and 176 animals from the ZL5 Clarifide Plus from Zoetis (Kalamazoo, MI). The Beta Casesin A2A2 genetics were 23% for control HO, 49% for HO, 40% for ProCross, and 53% for GrazeCross. The control HO had a greater percentage (P < 0.01) of cows that were A1A1 (27%) than the HO (12%), ProCross (14%) and GrazeCross (8%). Predicted transmitting abilities for genetic traits were from the December 2019 genetic evaluation from the Council on Dairy Cattle Breeding (Bowie, MD). Independent variable for statistical analysis of genetic traits with PROC GLM was the fixed effect of genetic line and A2 status. The control cattle had (P < 0.01) lower NetMerit$ (-$758) compared with the contemporary HO (+367), ProCross (-$7), and GrazeCross ($14) cattle, respectively. Within each breed group the A2A2 cattle were similar (P > 0.52) to A1A1 cattle for NetMerit$. Future studies will compare the genetic lines with genome-wide association analysis for production and health traits.

Keywords: genetic selection, organic, health.