Adjusted 205-Day Weaning Weight Calculator (BIF Method)

How it works

205-day weight = (weaning weight − birth weight) ÷ age in days × 205 + birth weight + age-of-dam adjustment · Ratio = calf’s adjusted weight ÷ group average × 100

Calves are weaned at different ages and from cows of different ages, so raw weaning weights are not comparable. The Beef Improvement Federation (BIF) method projects each calf’s pre-weaning gain to a standard 205 days and adds a fixed amount for calves from young or old cows, which milk less than mature 5–10-year-old cows (for example +60 lb for a bull calf from a 2-year-old). Use weights taken between 160 and 250 days of age, and compare calves only within the same contemporary group with the ratio — 100 is the group average.

Worked example

A bull calf born at 35 kg and weaned at 220 kg at 200 days, from a 7-year-old cow: (220 − 35) ÷ 200 = 0.925 kg/day; × 205 = 189.6 kg; + 35 kg birth weight = 224.6 kg, with no age-of-dam adjustment. Against a group average of 210 kg, its weaning weight ratio is 107.

Sources: Beef Improvement Federation — Guidelines: Weaning weight · Alabama Cooperative Extension — Beef cattle performance record keeping (age-of-dam table)

Frequently asked questions