Background: The Osteopontin (OPN) is a highly phosphorylated glycoprotein in numbers of bovine tissues and milk. OPN has been reported to be associated with milk production in cattle. Objective: The genotype and allelic frequencies for OPN and its association with milk production will be evaluated in Iranian Holstein Bulls.   Materials and Methods: Bulls DNA (100) was isolated. Oligo was used f...

background: the osteopontin (opn) is a highly phosphorylated glycoprotein in numbers of bovine tissues and milk. opn has been reported to be associated with milk production in cattle.objective: the genotype and allelic frequencies for opn and its association with milk production will be evaluated in iranian holstein bulls.  materials and methods: bulls dna (100) was isolated. oligo was used for...

Nine measures related to breeding efficiency were used for comparisons among purebred Ayrshires, Brown Swiss, Holsteins, and Jerseys and between purebreds and 32 crossbred groups representing 2-breed, 3-breed, 5/8, and backcrosses by purebred sires and progeny of crossbred sires. There were four herds wi th Holsteins common to all, Brown Swiss and Jerseys in three herds and Ayrshires in one her...

 In US dairy herds, the current national average age at first calving is 25.2 months. Increasing first-lactation milk yield could improve milk’s life-cycle production efficiency and decrease emissions.  The productive life of dairy Holsteins in the United States born in 2000 decreased by 3.95 months compared with Holstein cows born in 1980. This negative trend needs to be halted to achieve en...