Final answer:
The stage that ends when piglets are weaned at 2-4 weeks is the farrowing stage in pig farming.
Step-by-step explanation:
The stage that ends when the piglets are weaned at about 2-4 weeks is the farrowing stage. Farrowing refers to the process of giving birth to piglets. During this stage, the piglets are dependent on their mother for nutrition and care. Once they are weaned and can eat solid food independently, the farrowing stage ends.
Learn more about Farrowing stage in pig farming