Crossbreeding as a strategy in dairy cattle herds

• This thesis aimed to explore benefits of dairy crossbreeding at herd level and form recommendations for dairy farmers, advisors, and breeding companies. A survey study revealed that Swedish dairy farmers can be divided into two groups: those supporting crossbreeding and those not supporting it. SimHerd Crossbred and ADAM were used to simulate various crossbreeding strategies and estimate the economic effects. Both terminal and rotational crossbreeding involving Swedish Red and Swedish Holstein increases the yearly economic return in organic and conventional Swedish production systems, compared with purebreeding Swedish Holstein. Also, terminal crossbreeding combined with the genetic benefits of sexed semen and genomic testing of purebred animals is economically beneficial. Terminal crossbreeding between a low-yielding native breed and a high-yielding breed improves the economic result. Combined with marketing of niche products, terminal crossbreeding may be beneficial as a strategy for conserving native dairy cattle breeds. Genomic breeding values for crossbred animals could be predicted with a model using summary statistics from purebred reference populations with almost as high prediction accuracies as if full genotype and phenotype information was available. Future research is needed on crossbreeding schemes utilizing genomic data and the effect of crossbreeding on the environmental footprint.

Ämnesord

LANTBRUKSVETENSKAPER  -- Bioteknologi med applikationer på växter och djur -- Genetik och förädling inom lantbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agricultural Biotechnology -- Genetics and Breeding in Agricultural Sciences (hsv//eng)

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