The researchers estimated the body weight of Holstein-Friesian cattle using multiple regression analysis. They collected data from 30 bulls aged one to five years, measuring body weight, body length, height at withers, chest depth, heart girth, and age. The study found a relationship between body weight and chest depth, as well as age. The estimated multiple regression equation showed that body weight could be predicted using heart girth and age, with a high accuracy of 95.6% and a small error of 22.59.