What livestock tool is used to measure the weight of an animal?

The weighing scale is the correct tool used to measure the weight of an animal because it provides a direct measurement of the animal's mass. Weighing scales come in various forms, including digital and mechanical options, and they are specifically designed to handle the weight of livestock. This accuracy is crucial for farmers and ranchers who need to monitor animal growth, determine feed requirements, and make management decisions based on weight.

Other tools mentioned, such as a ruler, measuring tape, and caliper, serve different purposes. A ruler is typically used for measuring length or height, while a measuring tape can also measure length and is primarily used for dimensions in a more flexible manner. A caliper measures the distance between opposite sides of an object, often in more precise applications, but none of these tools can provide weight measurements required for livestock management.