title: Heterozygous Inverdale ewes show increased ovulation rate sensitivity to pre-mating nutrition.
abstract: This study aimed to determine whether ewes heterozygous (I+) for the Inverdale mutation of the bone morphogenetic protein-15 (BMP15) gene with high natural ovulation rate (OR) show similar sensitivity to nutritional manipulation as non-carriers (++). Increasing pre-mating nutrition results in OR increases in sheep, but whether this effect occurs in ewes with naturally high OR is unknown. Over 2 years, I+ or ++ ewes were given high (ad libitum) or control (maintenance) pasture allowances for 6 weeks prior to mating at a synchronised oestrus, with OR measured 8 days later. The high group increased in weight compared with controls (+5.84kg; P<0.01), accompanied by increased OR (+19%; P<0.01). As well as having higher OR (+45%; P<0.01), I+ ewes responded to increased feed with a larger proportional increase in OR (+27%; P<0.01) compared with the response in ++ ewes (+11%; P<0.05), suggesting an interaction between BMP15 levels and nutritional signals in the follicle to control OR. Although litter size increases only tended to significance (+12%; P=0.06), extra feed resulted in over 50% of I+ ewes giving birth to more than three lambs, compared with 20-31% of I+ ewes on maintenance rations. This information can guide feed management of prolific Inverdale ewes prior to breeding.
authors.affiliation: Reproductive Biology, AgResearch Ltd, Invermay Agricultural Centre, Puddle Alley, Mosgiel, New Zealand. kristy.demmers@agresearch.co.nz
authors.forename: K J
authors.initials: KJ
authors.lastname: Demmers
authors.forename: B
authors.initials: B
authors.lastname: Smaill
authors.forename: G H
authors.initials: GH
authors.lastname: Davis
authors.forename: K G
authors.initials: KG
authors.lastname: Dodds
authors.forename: J L
authors.initials: JL
authors.lastname: Juengel
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D001835:Body Weight; D055430:Bone Morphogenetic Protein 15 / Q000235:genetics* / Q000378:metabolism; D003433:Crosses, Genetic; D005260:Female; D006579:Heterozygote; D008098:Litter Size; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena; D009154:Mutation; D010060:Ovulation; D011247:Pregnancy; D034561:Sheep, Domestic / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D013997:Time Factors
chemical_list: D055430:Bone Morphogenetic Protein 15