**8.4 Embryo transfer**

The heat stress shows adverse impact on embryos greatest sensitivity, however, occurs during the early stages of embryonic development which leads to reduced pregnancy.. The embryos develop some tolerance capacity towards heat stress at time of embryonic development (morula or blastocyst stage). As a result, using embryo transfer of frozen embryos harvested from non-heat stressed cattle's, it might be potential to raise to pregnancy rates in heat stress effected cattle. There are multiple number of adverse effects of heat stress on the pregnancy of cattle (**Figure 3**). Many recent studies have shown that embryo transfer can be used to avoid embryonic death within the first seven days of development, when the embryos are more vulnerable towards heat stress. At the time of the summer, the technique has the potential to increase pregnancy rates dramatically. Furthermore, studies advances in improving embryo heat stress resistance through genotype modification and the accumulation of endurance factors like insulin growth factor-1, which help provide a protection to cells from following types of stresses, can boost pregnancy rates with embryo transfer even more. However, embryos are more responsible towards heat stress early pregnancy and also cooling the inadequate number of instance. At the time of the sensitivity of embryo at peak under heat stress shows enhancement of the pregnancy ratios moderately. As example of the rate of pregnancy towards artificial insemination for cattle's that were chilled for eight days after acceptance of prostaglandin F, (PGF2) was 16% as compared to 6% for control [20]. The limited cooling is not considerably useful for rate of increasing rate of pregnancy due to heat stress. The cooling was started on heat stressed follicles function and stopped at later at the time of pregnancy. The following conditions have hindered widespread trade implementation of embryo transfer for decline the rate of heat stress [21]:


**Figure 3.** *Impact of heat stress on pregnancy of cattle.*
