Lawrence R. Schaeffer, EdwardB Burnside, Paige Glover and Jalal Fatehi
Abstract:
Progeny of Holstein females mated to sires of different breeds were genetically evaluated along with their purebred Holstein contemporaries born in the same herds using multiple trait animal models. The resulting estimated breeding values(EBV) of cows were averaged within breed ofsire and compared relative to progeny of purebred Holstein sires for various economic traits. All progeny were born since 2005, and only animals from herds with crossbreds were included in the genetic evaluation models. Crossbred cows were significantly below Holstein sired cows for 305-d EBV for milk yield, but were above Holsteins for fat and protein yields. There were no significant differences between crossbreds and purebreds forsomatic cell scores. Crossbred cows and heifers became pregnant sooner after each calving, had higher non-return rates, fewer services, and shorter gestation lengths than purebred Holsteins. Crossbred heifers and cows had lower stillbirth rates due to having smaller calves, and slightly better calving ease. Objectively measured conformation traits (seven) and milking speed and milking temperament were analyzed by multiple trait models.Differencesfor conformation favoured Holsteins over crossbreds. There were no significant differencesfor milking speed
ortemperament between crossbreds and purebreds.
Keywords: Crossbreeding, conformation, production,reproduction, milking speed, temperament, heifers, cows
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