Effects of cobalt/vitamin B12 status in ewes on ovum development and lamb viability at birth

Linda M Mitchell, John J Robinson, Robert G Watt, Thomas G McEvoy, Cheryl J Ashworth, John A Rooke, Cathy M Dwyer

Research output: Contribution to journalArticlepeer-review


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.
Original languageEnglish
Pages (from-to)553-62
Number of pages10
JournalReproduction, Fertility and Development
Issue number4
Publication statusPublished - 2007


  • Animals
  • Animals, Newborn
  • Behavior, Animal
  • Body Weight
  • Cobalt
  • Diet
  • Embryo Transfer
  • Female
  • Fertility
  • Ovum
  • Parturition
  • Pregnancy
  • Sheep, Domestic
  • Superovulation
  • Vitamin B 12
  • Vitamin B 12 Deficiency

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