title: Short communication: Is crossbreeding only beneficial in herds with low management level?
abstract: The economic benefit of crossbreeding has been well known for many years within dairy production. However, in most countries with an intensive dairy production, an extended use of systematic crossbreeding has not occurred. This may be due to the myth that heterosis is expressed mainly in low-producing herds. The aim of the study was to investigate the effect of heterosis with different management levels in Danish Jersey herds. More than 300,000 records of 305-d milk, fat, and protein yield from first-lactation Danish Jersey cows with different contributions from original Danish and US Jersey were analyzed using an animal model. The herds were distributed in 5 management groups based on production level. First, the results showed a large increase in additive genetic variance from the herds with lowest production level to the high-producing ones, and second, heterosis for all 3 production traits were lowest within the low-intensity management group and tended to be highest in the intermediate management groups. The results, therefore, support that crossbreeding is a breeding system that should be considered valuable for all management levels.
authors.affiliation: Department of Molecular Biology and Genetics, Faculty of Science and Technology, Aarhus University, PO Box 50, DK-8830 Tjele, Denmark. morten.kargo@agrsci.dk
authors.forename: M
authors.initials: M
authors.lastname: Kargo
authors.forename: P
authors.initials: P
authors.lastname: Madsen
authors.forename: E
authors.initials: E
authors.lastname: Norberg
mesh_terms: D000818:Animals; D002417:Cattle; D003612:Dairying / Q000191:economics / Q000379:methods*; D005260:Female; D006579:Heterozygote; D006823:Hybrid Vigor / Q000235:genetics / Q000502:physiology; D006824:Hybridization, Genetic; D007774:Lactation / Q000235:genetics*; D008892:Milk / Q000737:chemistry / Q000378:metabolism