Final answer:
The state that pioneered the use of egg yolk for extending the lifespan of semen samples is Iowa, and this practice plays a significant role in animal reproduction and the agricultural industry.
Step-by-step explanation:
The state responsible for using egg yolk to extend the lifespan of semen samples is Iowa. The extension of sperm lifespan through egg yolk is a practice within the field of animal reproduction technologies.
Egg yolk contains lecithin, a natural antioxidant, which acts as a protectant for spermatozoa during the freezing and thawing processes. This practice has become quite relevant in the agricultural industry, particularly within animal husbandry, to preserve genetics and improve breeding efficiencies.