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.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.