1 Records created or received by an individual, family or organisation (such as a government, cultural association, company or university) during its existence and selected to be kept permanently because they are considered to be of continuing value to society. 2  Unique and irreplaceable.
In domestic dogs, sexual maturity (puberty) occurs between the ages of 6 to 12 months for both males and females, although this can be delayed until up to two years of age for some large breeds. Pregnancy is possible as soon as the first estrus cycle, but breeding is not recommended prior to the second cycle.
Young dogs do not have quality sperm. Almost all dogs will have sperm by one year. Stud dogs are at their prime between 18 months and 4 years old (or 5), after that, the quality of the sperm starts to lessen, and the ability to penetrate eggs, lessens.