14.6.2 Population size

The population to monitor consists of all animals that can be mated: the maximum size of the breeding population. Looking backwards in the history of a breed its population size varies.

Therefore the first parameter to monitor is population size. A large population has the advantage of less chances for random drift and constrained inbreeding. In well managed commercial breeding populations the population size is determined before the breeding programs starts and is maintained in all generations later on. But in less controlled breeds, e.g. in horses or dogs, it depends of several factors how population size develops. In dogs the popularity of the breed might change; in horses low prices for foals may lead to less matings and in the long term to a decrease in population size.

The number of offspring born per year is the second parameter to monitor population size. Over years it presents the stability of a breed: is there an increase (favourable) or a decrease (unfavourable)? But in animal breeding we know that not all animals born will be used for breeding the next generation. They are not selected for breeding or the owner does not want to breed with the animal. The latter is often seen in species not kept for commercial purposes: dogs and horses.