title: Effects of cobalt/vitamin B12 status in ewes on ovum development and lamb viability at birth.
abstract: Scottish Blackface ewes from cobalt-deficient farmland were fed a diet containing 0.06 mg cobalt per kg dry matter from approximately 30 days before embryo recovery/transfer until lambing. Ewes remained untreated (-Co; n = 82) or were given an intraruminal cobalt-containing bolus to compensate for the dietary deficit (+Co; n = 82). Ewes used as embryo donors (-Co, n = 17; +Co, n = 16) were artificially inseminated with semen from a single Suffolk sire. Day 6 embryos obtained from -Co and +Co donors were transferred in singleton to -Co and +Co recipients in a 2 x 2 factorial-designed experiment to determine the effects of cobalt/vitamin B12 status during the periconception period (factor 1) and pregnancy (factor 2) on lamb viability at birth. Mean (+/- s.e.m.) circulating concentrations of vitamin B12 in -Co and +Co donors at ovum recovery were 182 +/- 10 and 1288 +/- 64 pmol L(-1), respectively (P < 0.001), and the number of corpora lutea per ewe ovulating was 9.9 +/- 1.6 and 14.4 +/- 1.3, respectively (P < 0.05). Treatment did not affect the proportion of recovered ova that contained >32 cells (viable) or the median stage of development (late morula), but viable ova recovered from -Co v. +Co ewes had a better morphological grade (2.0 +/- 0.1 v. 2.20 +/- 0.04, respectively; P < 0.01). There was no effect of treatment on the proportion of recipient ewes that became pregnant. Circulating concentrations of vitamin B12 were lower in -Co than +Co ewes during pregnancy (P < 0.001) and at birth in lambs born to -Co ewes compared with those born to +Co ewes (P < 0.001). There was no effect of donor or recipient cobalt/vitamin B12 status on lamb birthweight, neonatal vigour or neonatal rectal temperatures, but lambs derived from +Co v. -Co embryo donors were more active in the first 3 days after birth (P < 0.05). Results show that sub-clinical cobalt/vitamin B12 deficiency reduces ovulatory response in superovulated ewes and that periconception nutrition can affect neonatal lamb behaviour.
authors.affiliation: Sustainable Livestock Systems Group, SAC, Craibstone Estate, Bucksburn, Aberdeen AB21 9YA, Scotland.
authors.forename: Linda M
authors.initials: LM
authors.lastname: Mitchell
authors.forename: John J
authors.initials: JJ
authors.lastname: Robinson
authors.forename: Robert G
authors.initials: RG
authors.lastname: Watt
authors.forename: Thomas G
authors.initials: TG
authors.lastname: McEvoy
authors.forename: Cheryl J
authors.initials: CJ
authors.lastname: Ashworth
authors.forename: John A
authors.initials: JA
authors.lastname: Rooke
authors.forename: Cathy M
authors.initials: CM
authors.lastname: Dwyer
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology* / Q000523:psychology; D001522:Behavior, Animal; D001835:Body Weight; D003035:Cobalt / Q000008:administration & dosage / Q000172:deficiency*; D004032:Diet; D004624:Embryo Transfer; D005260:Female; D005298:Fertility; D010063:Ovum / Q000187:drug effects / Q000254:growth & development*; D036801:Parturition; D011247:Pregnancy; D034561:Sheep, Domestic / Q000254:growth & development* / Q000378:metabolism; D013480:Superovulation; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood; D014806:Vitamin B 12 Deficiency
chemical_list: D003035:Cobalt; D014805:Vitamin B 12