Which production trait in swine is not improved when crossed with a purebred sow?

In swine production, crossing with a purebred sow generally aims to enhance certain desirable traits through the benefits of hybrid vigor, also known as heterosis. This is especially useful for traits such as growth rate, fat quality, and carcass yield, which can be exaggerated in the offspring when hybridized with high-quality purebreds.

However, conception rate is primarily determined by the genetics and reproductive health of the sow rather than by the genetics of the boar being used for breeding. As a result, crossing a purebred sow does not typically lead to significant improvement in this trait. The genetic makeup of the sow and her management practices play a more crucial role in conception rates compared to hybridization effects. Therefore, while other traits may see enhancements from crossbreeding, conception rate does not benefit in the same way when paired with a purebred sow.