Which of the following statements is true regarding hybrid vigor?

Hybrid vigor, also known as heterosis, refers to the phenomenon where crossbred offspring exhibit improved or enhanced biological qualities compared to their purebred parents. This can include traits such as increased growth rates, better disease resistance, higher fertility, and overall improved performance. The correct statement emphasizes that crossbreeding can lead to these advantageous traits, as it combines the genetic diversity of both parent lines, often leading to a more robust progeny.

In contrast, the other statements do not accurately reflect the principles of hybrid vigor. Purebreds do not exhibit hybrid vigor since they lack the genetic diversity that comes from crossing different breeds. Additionally, hybrid vigor does not consistently decrease with each generation; in fact, the benefits may vary depending on the specific crossbreeding program and the genetic contributions of the parent lines. Lastly, hybrid vigor is related to the genetics from both the dam and sire, not solely from the dam's lineage. Understanding these concepts is crucial for anyone involved in livestock selection and breeding practices.