The ducklings in the pen are a protective measure to put a circle on their feet to prevent them from getting lost or being attacked by predators when they go out. It is feasible to raise ducklings with collars, but the following points should be paid attention to:

1. Choose a suitable circle: the size of the circle should be suitable for the toes of the duck, which should not only ensure the free movement of the duck, but also prevent the duck from leaving the circle.

2. Regular inspection and adjustment: After the ferrule, check the tightness of the ferrule regularly to ensure that it will not be too tight or too loose, which will affect the blood circulation and activities of ducks.

3. Provide enough water and food: Ducks need enough water and food to maintain their daily needs and ensure the normal operation of their diet and living environment.

4. Pay attention to the behavior and health status of ducks: If ducks are found to have abnormal behavior or discomfort, such as limping and loss of appetite, measures should be taken in time, and the collar may need to be adjusted or removed.