COI (Coefficient of Inbreeding)
What is a COI? The coefficient of inbreeding is the number used to calculate how closely related two individual animals are to each other or how inbred an individual is.
What is inbreeding? This is the mating of animals that are closely related.
What is line breeding? This is a highly strategized inbreeding. This may be used as a way of locking in desirable traits from one generation to another while minimizing the undesired traits.
What is the difference between line breeding and inbreeding? The majority of the difference is in the degree of separation. Inbreeding is: father to daughter, mother to son, and brother to sister. Line breeding involves more distantly related animals.
Some of the advantages of line breeding are:
- lock in desirable traits
- produce more consistent and predictable traits in the offspring
- establish genetic uniformity
Adverse effects of inbreeding:
- Decreased growth rate
- Decreased mature weights
- Decreased fertility
- Smaller offspring at birth
- Smaller litter sizes
- Increased death rate
- Decreased lifespan
- Decreased immunity (resistance to disease is weakened)
- Increased genetic defects such as cryptorchidism, absence of both testes, etc.
Most studies have shown that the effects become prevalent at a COI of 5% and are higher once you reach a COI of 10% and above. In terms of overall health, a COI of 5% or less is best, with the goal to be as close to zero as possible.
Line breeding can be a useful tool, but it is important that before moving forward with line breeding, you have done your homework, have a vast knowledge of breeding, and fully understand the pros and cons.
The majority of farmers and homesteaders should strive to keep their COI at or below 5% unless line breeding is the goal. If you have an animal with a higher COI, then making sure to pair it with another animal who has a low COI is going to ensure that the offspring have a lower COI.