title: Melatonin treatment prior to the normal breeding season increases fetal number in United Kingdom sheep flocks.
abstract: Litter size determined ultrasonographically at 45-90 days after mating in eight groups of commercial sheep (n=2609) treated with slow release melatonin implants immediately prior to the natural breeding season showed a 19% treatment effect averaged over the eight groups, from 148% to 167% (P<0.01) compared with controls (n=2499). Control groups had a litter size ranging from 124% to 194% thereby representing most commercial production systems in the UK sheep industry. This is the first large scale study of slow release melatonin implants in commercial UK flocks to demonstrate a significant positive effect on litter size when used before the natural breeding season. The data indicate that increased productivity and profitability could be achieved while maintaining desirable purebred characteristics.
authors.affiliation: Division of Veterinary Clinical Sciences, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, UK. Philip.R.Scott@ed.ac.uk
authors.forename: P R
authors.initials: PR
authors.lastname: Scott
authors.forename: N D
authors.initials: ND
authors.lastname: Sargison
authors.forename: A I
authors.initials: AI
authors.lastname: Macrae
authors.forename: M R
authors.initials: MR
authors.lastname: Gough
mesh_terms: D000818:Animals; D001947:Breeding / Q000379:methods*; D003692:Delayed-Action Preparations; D005260:Female; D008098:Litter Size / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D011247:Pregnancy; D011897:Random Allocation; D012756:Sheep / Q000502:physiology*; D016216:Ultrasonography, Prenatal / Q000662:veterinary; D006113:United Kingdom
chemical_list: D003692:Delayed-Action Preparations; D008550:Melatonin