A: If you do not have a scales and want to predict weight, then you could use frame size. The table uses frame score at different ages and relates the frame score to body weight. It is assumed that the body condition of the cattle is BCS 5 in the 1 to 9 scale when the frame score is measured.
Frame score is a score based on subjective evaluation of height or actual measurement of hip height in beef cattle. This score is related to slaughter weights at which cattle should attain a given quality grade or attain a given amount of fat thickness. In other words, frame score is a convenient way of describing the skeletal size of cattle. With appropriate height growth curves, most animals should maintain the same frame score throughout life while their actual height will increase. This allows one frame score value to be used regardless of when the animal was measured.
The recommended site for the measurement of frame score is a point directly over the hooks of a beef animal. The measurement is then adjusted based on age in months. The measurement is taken with a frame stick.
Nutritional level is the biggest influence on frame score, especially for young animals. Under-nutrition will decrease average growth rate and high levels of nutrition will enhance growth rate.
The frame score system and the adjustments for age are in the Guidelines For Uniform Beef Improvement Programs by the Beef Improvement Federation. You can go on line to get a copy of these guidelines, http://www.beefimprovement.org and click on Library.