Pregnancy Rates to Fixed Embryo Transfer of Vitrified IVP Bos indicus,Bos taurus or Bos indicus × Bos taurus Embryos

The pregnancy rates obtained after the transfer of cryopreserved in vitro‐produced (IVP) embryos are usually low and/or inconsistent. The objective of this study was to evaluate the pregnancy rates of Holstein, Gyr and Holstein × Gyr cattle after the transfer of vitrified IVP embryos produced with X‐sorted sperm. Seventy‐two Gyr and 703 Holstein females were subjected to ovum pickup (OPU) sessions, followed by in vitro embryo production using semen from sires of the same breeds. Embryos (1636 Holstein, 241 Gyr and 1515 Holstein × Gyr) were exposed to forskolin for 48 h prior to vitrification. The pregnancy rate achieved with Gyr dam and sire was 46.1%, which was similar (p = 0.11) to that of Holstein dam and Gyr sire (40.3%). Crossing Gyr dams with Holstein sires resulted in a pregnancy rate of 38.9% and did not differ (p = 0.58) from the pregnancy rate obtained with the cross between Holstein dams and Gyr sires. The rate obtained with Holstein dam and sire was 32.5%. The average pregnancy rate was 36.6%, and no difference was found in the proportion of female foetuses (88.8%, in average) among breeds (p > 0.05). In conclusion, transfer of cryopreserved X‐sorted embryos represents an interesting choice for dairy cattle. Despite the small differences between pregnancy rates, we highlight the efficiency of this strategy for all of the racial groups studied.     

冬季日光温室的保温措施及对天气性灾害的预防对策

高效节能日光温室以太阳能为主要能源 ,不加温或临时加温就能进行果菜类生产 ,但近几年发展的温室偏高偏宽 ,保温措施又跟不上 ,结果在1 999年冬至 2 0 0 0年春雪多、严寒的条件下 ,不少温室出现了 2℃以下低温 ,甚至冻害 ,使果菜类生产受到很大影响 ,造成了很大的损失。对此 ,我站经过试验和调研 ,提出如下的保温措施及对天气灾害性的对策 ,使果菜类冬季能在日光温室得以正常生长 ,进一步提高冬季蔬菜生产的经济效益和社会效益 ,保证我市保护地蔬菜生产持续发展。1　温室结构与保温的关系沈阳市地处北纬 41°以北 ,冬至太阳高度角低 ,中午 …     

箱型矮栏养猪好

自1960年来,已建造了数千幢部分或全部漏缝地板的肥育猪舍,但每头肥育猪的空间有限,通常为O.54~O.64平方米.在西欧进行的比较试验证明,当采用部分漏缝地板,且每头猪有o.70平方米空间时,技术效益较好.而如果猪能在箱型矮栏里休息,效果就更佳好动的肥育猪一般不怕贼风或低温的影响.试验表明,把饲喂和排粪区与躺卧区分开,是很有利的.躺卧区三面能够关闭,并可用顶盖覆盖,以创造