Pigs are one of the most important livestock reared by the Nagas since time immemorial. They are an integral part of Naga livelihoods and culture. Amongst the livestock, pigs account for more than 55 percent of the livestock population and the state also stand highest in per capita consumption of pork in India. The tribals prefer to consume fresh pork which is home grown. Although the demand for local pork is increasing day by day our farmers could not produce it due to multiple reasons. One of the obvious reasons for non performance of our piggery farmers are due to inbreeding in pigs.
What is inbreeding in pigs?
The mating of the same breed that is closely related to one another is called inbreeding. To be more specific inbreeding involves the mating of related individuals within 4 to 6 generation. Inbreeding can be of close breeding where father is crossed with daughters, son is crossed with mother, full brother is crossed with full sisters and line breeding in which half brother is crossed with half sister, cousin crossed with cousin etc.
The effects of inbreeding in pig production
An individual receives genes from each parent i.e. father and mother. If the parents are related by blood the offspring is more likely to get genes that are identical genes from each parent. An inbred individual carry undesirable genes which is received from identical members i.e. parents. This system of breeding in which parents are related is used from generation to generation leads to a decline in performance called inbreeding depression.
One of the effects of inbreeding will be decrease in litter size i.e. the number of piglets born will be less. For example, a farmer had 12 piglets which is a result of the cross between a male and a female that are not related by blood. From him, a male and a female piglet was taken by another farmer to his home. After attaining sexual maturity he crossed the same siblings i.e. brother and sister. The female will give about 9 piglets which is very less as compared to her mother. Here, about 25% less number of piglets of smaller and weak piglets are born and some of them were born dead. From, these siblings another farmer took a male and a female piglet to his home. After attaining maturity the same siblings i.e. brother and sister is crossed. The results from such breeding produced 6 piglets by the sow which is 50% less number with very small and weak piglets as compared with the first sow (grandmother) and some of them were born dead.
Suggestion for farmers in rural areas
For crossbreeding i.e. breeding of unrelated blood, the male pig for breeding should be exchanged between different villages. Here, the male pig is taken from one village to another village for crossing the female and vice versa for breeding male. In this way the inbreeding is avoided. The practice should be followed every year for breeding male which must be changed with un-related herd to avoid inbreeding problems.
Conclusions
In most of the villages the farmers rear male pig for meat purpose after castration. This leads to shortages of breeding male and only a few maintains the male for breeding purpose. In some case, only a single male is available for crossing the entire female in the villages irrespective of the blood relations to the male pig. In such scenario the vices of inbreeding will be observed to a great extend. Inbreeding will lead to some undesirable traits like hernia and cryptorchidism. It increases mortality or the death rate of the piglet’s generations to generations as their immune system becomes weak. It leads to low libido for inbred sows and boars. It leads to few eggs during oestrus for gilts, hence farrowing small litter (less number of piglets). Hence inbreeding to any degree or extend should be avoided as much as possible.
Submitted by-
Dr. S Sarendi Walling
ACTO (Animal Science)
KVK, Yisemyong, Mokokchung