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Performance of Holstein clones in the United States. Photo courtesy Infigen. H.D. NORMAN, * ,1 T.J. LAWLOR, 2 and J.R. WRIGHT 1 1 Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350, USA 2 Holstein Association USA, Brattleboro, VT 05302, USA
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Performance ofHolstein clones inthe United States Photo courtesy Infigen H.D. NORMAN,*,1 T.J. LAWLOR,2 and J.R. WRIGHT1 1Animal Improvement Programs Laboratory Agricultural Research Service, USDA Beltsville, MD 20705-2350, USA 2Holstein Association USA, Brattleboro, VT 05302, USA *dnorman@aipl.arsusda.gov 301-504-8334
National Research Council (USA) • Subcommittee to identify and to prioritize science-based risks of genetically modified animals • Report will decide regulation of cloned animals by U.S. Food and Drug Administration
Cloning technology • Embryo splitting • First U.S. registered Holstein calves: 1982 • Identical nuclear and mitochondrial DNA • Nuclear transfer • First U.S. registered Holstein calves: 1989 • Nearly identical nuclear DNA, but different mitochondrial DNA • Almost no recording of recipient cell identity • Full siblings versus identical animals
Objectives • Document performance of clones: • Yield: milk, fat, protein • Fitness: somatic cell score (SCS), productive life (PL) • Examine performance differences between embryo-split and nuclear-transfer clones
Data • Holstein Association USA registrations for embryo-split and nuclear-transfer clones • Gender • Birth year • Pedigree merit • Mean of parent predicted transmitting abilities (PTAs) • Clone type (embryo split vs. nuclear transfer) • All U.S. Holsteins born in same year and milk recorded through Dairy Herd Improvement
Conclusions • Decreased number of embryo-split males and all nuclear-transfer clones • Animals selected for cloning slightly superior genetically to population for yield traits • Yields similar for nuclear-transfer clones and their non-cloned full siblings • Yields of embryo-split clones slightly less than yields of their non-cloned full siblings