Male pigs can be ready to breed as early as four months old, although six to eight months old is more common. Sires used for artificial insemination is often selected based on their block genes, which produce offspring with superior muscling and leanness. The age at which a male pig reaches puberty is influenced by many factors, including nutrition and genetics. Good nutrition is essential for genital development and semen production. For example, boars fed a high-protein diet tend to reach puberty at an earlier age than those fed a lower-protein diet. Genetics also plays a role in when a male pig will reach puberty; certain breeds tend to mature faster than others. However, it is important to note that body size is not always an accurate indicator of reproductive maturity. Some small breeds may be fully mature by four months old, while some large breeds may not reach puberty until they are eight or nine months old. Ultimately, the best way to determine when a male pig is ready to breed is to have him examined by a veterinarian or qualified animal reproductive specialist