title: Sex of co-twin affects the in vitro developmental competence of oocytes derived from 6- to 8-week-old lambs.
abstract: Several intrinsic factors (age, genotype, liveweight) influence the reliability of juvenile in vitro fertilisation embryo transfer (JIVET) programs. Limited evidence indicates that variability between lambs is reduced in twin-born lambs. We examined the impact of birth type (single, twin, triplet) and sex of the co-twin (with age, birthweight and liveweight as covariates) on JIVET outcomes. Birth type did not influence any parameter studied. However, blastocysts produced, as a percentage of embryos cleaved or total cumulus-oocyte complexes collected, was higher (P<0.05) for females born with a female co-twin (67.0±6.1, 57.5±6.0 respectively) compared with those born with a male co-twin (26.9±6.5, 22.3±6.2 respectively; least-square mean±s.e.m.). Blastocyst rates for lambs born with a male co-twin did not differ significantly from lambs born either as singles (39.5±6.7%, 34.6±6.5% respectively) or triplets (43.1±10.6%, 36.5±10.3% respectively). Other parameters were not influenced by sex of the co-twin. These results are indicative of an enhancement effect of the female co-twin on oocyte development. From a practical perspective, selecting lambs for a JIVET program based on litter size and sex of the co-twin is warranted.
authors.affiliation: South Australian Research and Development Institute, Turretfield Research Centre, 129 Holland Road, Rosedale, SA 5350, Australia.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Kelly
authors.affiliation: South Australian Research and Development Institute, Turretfield Research Centre, 129 Holland Road, Rosedale, SA 5350, Australia.
authors.forename: David O
authors.initials: DO
authors.lastname: Kleemann
authors.affiliation: School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, Mudla Wirra Road, SA 5371, Australia.
authors.forename: Hayley
authors.initials: H
authors.lastname: McGrice
authors.affiliation: School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, Mudla Wirra Road, SA 5371, Australia.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Len
authors.affiliation: School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, Mudla Wirra Road, SA 5371, Australia.
authors.forename: Karen L
authors.initials: KL
authors.lastname: Kind
authors.affiliation: School of Animal and Veterinary Sciences, University of Adelaide, Roseworthy, Mudla Wirra Road, SA 5371, Australia.
authors.forename: Will H E J
authors.initials: WHEJ
authors.lastname: van Wettere
authors.affiliation: South Australian Research and Development Institute, Turretfield Research Centre, 129 Holland Road, Rosedale, SA 5350, Australia.
authors.forename: Simon K
authors.initials: SK
authors.lastname: Walker
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology; D004624:Embryo Transfer / Q000662:veterinary; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary; D008098:Litter Size; D008297:Male; D054315:Oocyte Retrieval / Q000662:veterinary; D009865:Oocytes / Q000254:growth & development*; D011247:Pregnancy; D012727:Sex Characteristics; D034561:Sheep, Domestic / Q000254:growth & development*