What are the common drawbacks of breeding programmes?

In the zoo, mostly one or two pairs of a species and their young ones are kept together; therefore, there is a risk of 'inbreeding'. For example, when father and daughter or cousins give birth to young ones, negative traits are likely to emerge in them; the fresh brood is usually weaker and more prone to diseases. Since an endangered species must be kept healthy, healthier animals are bought over from other zoos or from the wild for breeding. This refreshes the genetic material and makes the positive traits dominant. Even when conservation of species is not the main concern, zoos exchange animals in order to prevent inbreeding.