EMBRYO TRANSFER TECHNIQUE IN ANIMALS : AN INTRODUCTION

Pashu Sandesh, 17 March 2020

Dr Vikas Sachan, Dr Akshay Kumar

Rearing animals along with agriculture has been a major profession for farmers for centuries. The animals are not only reared for various agricultural related tasks, drought purposes but also for their different products as milk, wool, meat etc which are major sources of income generally in rural areas. The compost made by their dung boosts the agricultural land potential for agricultural production. So it is very important to maintain the reproducibility of the livestock for continuous production.

Heat detection and right time insemination with successful conception in animals is an essential event. Nowadays, either natural insemination is provided by keeping one or two buffaloes bull or cattle bull of apparently good breed. In such a situation, the cow and buffalo may not get pregnant every time because of over-exhausted bulls or poor quality semen from old or poor breed bull. It directly affects the breeding ability and productivity in terms of lactation which ultimately impact falls on the farmers' income. These repeat breeder and unproductive animals are difficult to manage and rear and animal owner is compelled to leave them. 

Although conception rate is more in natural services, Artificial insemination overcomes many drawbacks of natural insemination like disease transmission, transportation of female to male and lesser females insemination coverage etc. Like artificial insemination, embryo transfer is nowadays quite popular technology imparting its significant role in the genetic development and conservation of animals. As in artificial insemination, one can get maximum offspring from semen of one male, embryo transfer also facilitates to get maximum genetically advanced progenies by using multiple eggs from one high genetic merit female. Additionally, through this technology, we can use not only such female animals which cannot be considered genetically good but suitable for carrying pregnancy as the recipient but also such females who are of good genetic merit but cannot carry the pregnancy (due to senility, any disease or other physical impairments) as a donor.  

Walter Hepe was the person who did the embryo transfer in 1890. Angora rabbit embryo was transplanted into Belgian females by him. Over time, this technology has also been successfully used in cow, buffalo, sheep, goat and sow etc. Embryo implantation is a complex process that involves the selection of donor female, superovulation treatment, artificial insemination of the female, collection and grading of embryos, selection and preparations for the recipient females, embryo transfer and lastly pregnancy diagnosis.

In this technique, a female of high genetic merit is selected as a donor and subjected to definite protocols with follicular stimulating hormone (FSH) or pregnant mare serum gonadotropin hormone (PMSG) in order to superovulate i.e. to get maximum no. of eggs. These females are artificially inseminated with good quality semen. After about seven days the formed embryos are collected from the donor in a very sophisticated manner. These embryos are subjected to grading process according to their appearance, shape and colour and then only good to high-quality grade embryos are transferred to the uterus of recipient females. Recipient females (healthy and free from any disease) are also synchronized with donors for their heat and ovulation by using reproductive hormones so that they can receive embryos for proper implantation and their development. Initially, surgical techniques were used for embryo transfer but at present, non-surgical techniques are more popular. All these protocol actions are costly and need high technically skilled personnel.

By the artificial insemination, only one progeny could be obtained from a good breed female but 6.5 to 7 calves can be obtained by embryo transfer technique. Normally, a cow can produce a maximum 10 times during her life, but about 20-22 embryos that can be obtained and transplanted from a donor cow by embryo transfer technology. In this way, embryonic implants can prove better in many ways than artificial insemination. Objectives like increased rate of genetic development, prevention of genetic diseases, disease-resistant progeny, preservation of rare animals, production of an improved new breed, faster progeny testing etc can also be obtained by embryo transplantation technology. But it has been found that despite all the above characteristics, the use of embryonic implantation technology has not been more prevalent. Due to high cost, lack of sound knowledge and technical skill, this technology is restricted to only some special and best animal farms or labs. To promote this technology, there is a need for low-cost processing an increased number of skilled persons, so that farmers can get maximum benefit globally.

Dr Vikas Sachan, Dr Akshay Kumar

Department of Veterinary Gynecology & Obstetrics, DUVASU, Mathura (UP)