The Production And Nursing Of The Calves Derived From Somatic Cell Nuclear Transfer

Nuclear transfer including embryonic cell nuclear transfer (ECNT) and somatic cell nuclear transfer (SCNT), is a alternative approach in addition to the dominately sexual reproduction. A variety of animal species have been cloned through SCNT technology, the cloning efficiency, however, is extremely low which become the the major bottle-neck obstacle for the economical application of this technology. Although the exact mechanisms affecting the cloning efficiency are not clear, the oocyte cytoplasmic status, donor cells and detailed cloning protocols probably contribute to the extremely low offspring rate. More important, the high death rate of the newborn animals, usually over 50%, makes the cloners and breeders somewhat depression. The recipient cow's periparturient management and newborn calves'care should have a great impact on the survival rate of the neonatal cloning animals. To our knowledge, this is the first study focused on specific and systematic observations of the cloned calves. During perinatal period, perinatal and the birth of the caves, the recipient cows and the calves were kept an eye on almost 24 hr per day. After transfer of the cloned embryos to the synchronized recipients the pregnancy rate was 50% after 60 days transfer. Sixth month later 44% pregnancy were still maintained, and 33.3% of the recipients delivered healthy calves. Different treatment and management were conducted according to the newborn calf's appearances and physiological state. A series of physiological indexes such as body temperature, heart rate, respiratory frequency, nose wetness, etc, were measued and careful theropy were taken for the susceptible diseases. Foreign body pneumonia, omphalitis and calf diarrhea are the most susceptible diseases of the newborn cloned calves. With great careful careful treatments and nursings of the recipient cows and the calves the survival rate reached over 80%.Through our careful observations and treatments, a practical protocols for the the managements and nursing of cloned calves were established, which would be beneficial for the industrialization of the cattle cloning and transgenic cloning.