title: Fertility of norgestomet treated suckler cows.
abstract: Four studies are described involving 3050 single suckled mainly Hereford-Friesian cross beef cows treated with norgestomet and oestradiol valerate to control the ovarian cycle. In study 1 the effect of insemination timing on pregnancy rate was studied. A greater proportion of cows inseminated 48 and 72 hours after treatment became pregnant than after a single insemination at 48 hours. In study 2 large variations in fertility among farms were recorded in field trials of norgestomet and oestradiol valerate. In study 3 the effect on fertility of nutrition, weight and body condition was examined. In study 4 57.9 per cent of 1113 treated cows became pregnant to insemination at 48 and 72 hours. Cows were fed a balanced ration designed to provide for a predicted daily milk yield of 9.0 kg for a 12-week period starting six weeks before insemination. The range of fertility was from 36.7 per cent to 94.9 per cent.
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology; D004971:Estrus / Q000187:drug effects; D005260:Female; D005298:Fertility; D007315:Insemination, Artificial / Q000662:veterinary; D010060:Ovulation / Q000187:drug effects; D011247:Pregnancy; D011282:Pregnenediones / Q000494:pharmacology*
chemical_list: D011282:Pregnenediones; D004958:Estradiol