Need of commercialisation of artificial insemination in pigs

Tukheswar Chutia / Bhabesh Mili / MO Kurien / G Dhanan Jaya Rao *

Livestock is an integral part of agriculture farming in India. It contributes 4.1% of total National GDP, which is highest amongst agriculture and allied sectors.

Among all livestock species, pig has a huge potential to contribute faster economic return to the farmers, because of high fecundity, better feed conversion efficiency, early maturity and short gestation interval. The marginal farmers, especially in entire North Eastern region of India have enormous opportu- nity to improve their socio-economic status and livelihood through piggery.

Almost every household of North Eastern region consume pork. Latest livestock census data shows a declining trend of pig population from 13.52 million (17th Livestock census) to 9.06 million (20th Livestock census). Having potential to improve socio economic status and livelihood of tribal peoples, especially in North Eastern States of India, it necessitates improvi- sation of traditional piggery practices, especially breeding.

Piggery in India is mostly confined within the weaker section of rural society, especially within tribal masses. Although the Government has offered attractive subsidy and scheme to the livestock entrepreneurs to boost up piggery industry, still this industry is not growing remarkably in our country. One of the major causes of declining trend of pig population is sticking with traditional method of breeding via natural service.

In this system, a community boar is use for breeding within that community. No organized germplasm centre is available for pig in our country. Therefore, farmers are solely dependant on natural service unlike developed countries.

The rearing of boar for breeding is cost effective as well as is not feasible for backyard pig farmers, where they are confined to maximum 2 to 3 nos. of pig only. Thus, widespread use of AI will be an alternative to age old natural service with superior male germplasm for breeding will defiantly boost up piggery industry in our country.

A success of AI in terms of fertility lies on decision of right time for AI in a breed able female animal. Pig is a polyoestrous and polytomous domestic animal, can yield many crops in a year. Gilt attains maturity at the age of 6-11 months depending on the size, breed and nutrition and other managemental factors.

However, poor body condition, imbalanced nutrition may delay the onset of puberty and sexual maturity. The age of sexual maturity of exotic breed, crossbred and local pig varies from 9-11 months, 8-11 months and 6-7 months, respectively.

The length of estrous cycles varies from 18-24 days in pig. The duration of estrus is 2-3 days; this may vary according to breed and age of the pig. Detection of estrus is paramount in order to achieve success in pig breeding. The estrus sign and symptoms are almost same in both gilts and sows; however the duration and intensity may vary.

The signs of estrus includes swelling and reddening of vulva, pink and moist of vulva mucous membrane, mucus discharge, mounting on other animals, excited for male, off fed, pressing the swollen vulva against hard wall or floor, standing reflex with erect ears and arched back with rigid, motionless posture etc.

It is always recommended that the female should always be bred or inseminated when it is in standing heat or estrus. However, it can’t be detected in all cases, which can be easily recognized in the presence of a mature boar.

Breeding Management

The gilt should be bred only when it is physically fit and having the proper growth at the time of estrus. It is always recommended that gilt should not be bred in first heat/ estrus as it will most likely result in poor quality oocytes. Fence line contact or direct contact of the mature breeding boar for 15-20 minutes per day, stimulate the hypothalomo-pituitary-gonadal axis of gilts, and thereby hasten puberty.

Gilt has a tendency to show signs of estrus when other pen mates come to estrus. Therefore, housing estral and non-estral gilts or sow together may enhance reproductive activity of the delayed pubertal gilts.

The delayed puberty can be overcome by hormonal therapy. Numbers of exogenous hormones have been used for augmentation as well as estrus synchronization in developed countries to enhance the reproductive performance in pig. Estrus synchronization coupled with fixed-time AI will be viable option to improve fertility rate in pig.

A healthy adult sow usually comes into estrus at around 5-7 days after post weaning. However, it also depends on farrowing to weaning interval. In commercial pig farm, weaning is done at various days of lactation, viz. 28 days, 35 days, 42 days or 56 days.

Early weaning at 28 or 35 days of lactation does not have much effect on body weight loss in sow. Thereby, sow may be ready for next breeding/service within a week after weaning. The post weaning body weight has immense effect on reproductive performance in sow.

A healthy sow exhibits next heat at the earliest, immediately after removal of lactation and suckling stimulus. However, weaning should not be done too early because it will depress the litter size. Sucking stimuli inhibit hypothalamo-pituitary-gonadal axis. Thus, removal of suckling stimulus causes activation of the same.

A plan weaning of sow with different lactation length also render the estrus synchronization, this is called “natural synchronization of estrus”. Understanding of endocrine profiles of pig especially on female reproduction, which has opened up a new vista in piggery through synthetic hormones therapy for enhanced reproductive effi- ciency, especially estrus synchronization coupled with fixed time AI.

Artificial Insemination of Pig

In Artificial Insemination, processed and preserved semen collected from genetically superior boar is deposited in the female reproductive tract at the time of estrus/heat by means other than sexual intercourse. A double insemi- nation is always ideal to meet maximum conception and fertility rate. Generally, AI is done on second day evening from the day of onset of estrus followed by third day morning at 12 hours interval in sow.

In contrast, gilt should be inseminated on second day morning followed by late evening dose on the same day. Procedure of AI in pig is as follows:

1. Clean the vulva and perennial area of female pig with a tissue or blotting paper.
2. Stimulate the pig in a way that mimics the action of a boar by giving pressure on its back, stimulation of the flanks and gentle massage of the udder.
3. Take a sterilized catheter and lubricate the tip of the catheter with a sterile non-toxic gel.
4. Spread the vulva and gently insert the catheter upward and forward into the vagina anticlockwise as far as it will go so that it will get locked into the cervix.
5. Fit the semen container tightly into the open end of the catheter. Hold the semen container in upward direction with one hand and stimulate the pig simultaneously with the other hand.
6. Squeeze the empty semen container just after completion of flow of semen into the tract to prevent backflow of semen. Stimulate the pig for 1-2 minutes.
7. Remove the catheter slowly and gently clockwise.

Conclusion

Artificial Insemination technique has huge potential to improve livelihood of tribal farmers through piggery, especially in entire North Eastern states of India. This technique is only for cyclic animal, whose reproductive status is known.

Exogenous hormonal therapy for manipulation of female reproduction will help a breeder to predetermine time for fixed time AI. Estrus synchronization coupled with a fixed time artificial insemination will minimize the cost of breeding, increase conception and fertility rate. Hence, commercialization of AI in pig will definitely boost up piggery industry in our country.