In Breeding

The hazards of breeding Hamsters' bought from the local Pet Store, or Pet Shop.

Some people intentionally buy a pair of Hamsters' for breeding purposes from their local pet store without realising the risks that may be involved directly to the offspring’s produced by the mating pair. Hamsters that are bought from pet shops are predisposed to carrying recessive traits owing to the breeding practices of many commercial breeders. Recessive traits are difficult, if not near impossible, for a novice breeder to identify carriers as recessive traits are unseen and often produce unhealthy undesirable traits in siblings. Inherited recessive traits become outwardly obvious and visible only when two copies of the gene for that trait are present, as opposed to a dominant trait where one copy of the gene for the dominant trait is sufficient to display that trait.

Most pet shops sell hamsters that come from breeding mills, or farms, (commercial breeders) these animals are bred purely for profit and are bred in large numbers. Breeding mills may use "Inbreeding" or "Line breeding" techniques to produce their saleable stock (the pups) There is no other easy way of breeding such large quantities and many of these commercial breeders are affected by inbreeding depression which can increase the harmful effects on any future offspring’s survival and reproduction.

Inbreeding is defined as the use of close relatives for breeding such as mother to son, father to daughter, brother to sister etc: Rarely, do they introduce alleles from a different population which can reverse inbreeding depression. Inbreeding increases the overall homozygosity of offspring’s compared with mating between unrelated animals (out breeding, or out crossing)

Line breeding is a form if inbreeding, father to daughter, son to mother etc: There is no clear distinction between the two terms, only that line breeding may encompass crosses between individuals and their descendants or two cousins. Line breeding is less likely to cause defects in the first generation than does inbreeding. However, over time line breeding can reduce the genetic diversity of the population and cause problems relating to a small gene pool that may include an increased prevalence of genetic disorders, this in its’ self can lead to inbreeding depression.

The Syrian hamster is generally recognized as a population bottleneck species (genetic bottleneck) owing to the way they were introduced into captivity many years ago. Inevitably this means they have a very low genetic variation. Population bottlenecks can markedly increase inbreeding due to a reduced gene pool, and may increase genetic drift as the rate of drift is inversely proportional to the population size. As a result first-generation inbred individuals are more likely to show physical and health defects.
Breeding between closely related individuals may result in more recessive deleterious traits manifesting themselves because the genomes of the mating pair are very similar resulting in very unfit individuals: including:

Reduced fertility.
Increased genetic disorders.
Lower birth rate.
Higher infant mortality rate.
Slow growth rate.
Loss of immune system function.

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