Yang H, Hughes P E, Rodway R G, Varley M A
Department of Animal Physiology and Nutrition, University of Leeds.
Vet Rec. 1988 Mar 12;122(11):257-9. doi: 10.1136/vr.122.11.257.
Thirty large white cross Landrace prepubertal gilts from five litters were allocated at random within litters to one of six treatment. All the gilts were given three daily intramuscular injections of 6 micrograms/kg liveweight of oestradiol benzoate but the first injection was given at either 100 days, 120 days, 140 days, 160 days, 180 days or 200 days old. From the time the first oestrogen injection was given, until the end of the experiment, the gilts were allowed daily contact with a boar for 20 minutes. The gilts were mated with a mature boar at the appearance of the second oestrus and they were slaughtered 20 days later. The numbers of gilts ovulating in the treatment groups were determined from plasma progesterone concentrations measured twice weekly throughout the experiment. The numbers of gilts ovulating within 10 days of the oestradiol benzoate injections were 3 of 5, 1 of 5, 0, 0, 3 of 5 and 1 of 5, respectively, in the groups first treated at 100 days, 120 days, 140 days, 160 days, 180 days and 200 days old. For those gilts which were successfully mated, no significant differences were observed between the treatment groups in the number of viable embryos per gilt.
从五窝中选取30头青春期前的大白长白后备母猪，在窝内随机分配到六种处理之一。所有母猪均每日肌肉注射三次，剂量为每千克体重6微克苯甲酸雌二醇，但首次注射分别在100日龄、120日龄、140日龄、160日龄、180日龄或200日龄时进行。从首次注射雌激素开始，直到实验结束，母猪每天与公猪接触20分钟。母猪在第二次发情出现时与成年公猪交配，并在20天后屠宰。在整个实验过程中，通过每周两次测定血浆孕酮浓度来确定各处理组中排卵的母猪数量。在100日龄、120日龄、140日龄、160日龄、180日龄和200日龄首次接受处理的组中，在苯甲酸雌二醇注射后10天内排卵的母猪数量分别为5头中的3头、5头中的1头、0头、0头、5头中的3头和5头中的1头。对于那些成功交配的母猪，各处理组每头母猪的存活胚胎数没有显著差异。
