Drew S B, Wishart D F, Young I M
Vet Rec. 1979 Jun 9;104(23):523-5. doi: 10.1136/vr.104.23.523.
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.
描述了四项研究，涉及3050头主要为赫里福德-弗里生杂交肉牛的单胎哺乳母牛，这些母牛用诺孕美特和戊酸雌二醇进行处理以控制卵巢周期。在研究1中，研究了授精时间对妊娠率的影响。与在48小时进行单次授精相比，在处理后48小时和72小时进行授精的母牛中，怀孕的比例更高。在研究2中，在诺孕美特和戊酸雌二醇的田间试验中记录了不同农场之间生育力的巨大差异。在研究3中，研究了营养、体重和身体状况对生育力的影响。在研究4中，1113头接受处理的母牛中有57.9%在48小时和72小时授精后怀孕。在授精前六周开始的12周期间，给母牛饲喂一种平衡日粮，设计目的是提供预计每天9.0千克的产奶量。生育力范围为36.7%至94.9%。
