Final answer:
The question concerns the practices of livestock management, specifically tagging and selling bull calves, which falls under the subject of Biology. Yellow tags usually carry information about the calves, and selling within the first 2 weeks relates to management and economic strategies.
Step-by-step explanation:
The practice of tagging bull calves with yellow tags and selling them within the first 2 weeks is related to livestock management, a subject within the field of Biology. These practices are used as part of cattle identification systems, which help farmers keep track of their livestock, manage breeding programs, track growth and health metrics, and manage sales. The color-coded tag system often indicates specific information about the animals, such as age, sex, or vaccination status. In this system, yellow tags might be designated for bull calves specifically. The decision to sell them within the first 2 weeks is generally related to the farm's management practices and economic considerations.