Yield grades estimate post-harvest beef carcass cutability—the relative amount of lean, edible meat from a carcass. As with post-harvest carcass quality grading, yield grading is voluntary and paid for by the meat packer.

While beef producers may be affected by yield grades, consumers are not typically interested in yield grades.

AMS market data shows that while about 95% of carcasses on packing plant rails get quality graded, only about 25% presently receive yield grades. The high volumes associated with modern meat packing make it impractical to calculate a yield grade for every carcass. In-house graders can though, at line speed, estimate carcass yield based on a quick assessment of fat cover and conformation.

Of the 40+ AMS certified beef programs, only two recently listed USDA yield grade in their specifications—and those had very liberal acceptance for fat content. Some industry analysts suggest that today there’s less need for yield grading as carcasses have become more uniform compared to decades ago when carcasses were highly variable in terms of cutability.

Determining yield grades

USDA Agricultural Marketing Service (AMS) graders calculate yield grades by using an equation that incorporates fat thickness over the rib, percent kidney/pelvic/heart fat (KPH%), hot carcass weight, and ribeye area.

Related:Body condition scoring

The five USDA yield grades for beef carcasses are 1-5. The lower the number the higher the yield of closely trimmed boneless retail cuts.

When asked to do so, AMS graders use a three-step method for calculating yield grade:

1. First a preliminary yield grade (PYG) is determined by the fat thickness at the 12th rib. PYG = 2.0 + (2.5 x fat thickness).

2. PYG is adjusted using an estimate of the ribeye area and carcass weight. The PYG is adjusted by 0.3 for each square inch change in ribeye from the size given for a particular carcass weight. If a carcass is estimated to be above average in muscling, the adjustment is subtracted from PYG, if its below average then the adjustment is added. PYG adjustment = (required REA - Actual REA) x 0.3.

3. The average amount of KPH for a steer is 2.5%. Thus, the adjustment for every 1% change above or below 3.5% is 0.2 of a yield grade. If the internal fat is above 3.5%, the adjustment factor is added; if below 3.5%, the adjustment factor is subtracted. Adjusted PYG = (Actual KPH – 3.5) x 0.2.

Example

Fat Thickness = 0.2 in.

Ribeye Area = 14.5 sq. in.

Live Weight 1130 lb., dressing percent is estimated at 62%

Carcass Weight = 700 lb.

Percent Internal Fat = 2.5%

Related:Special needs for old cows

Answer

Preliminary Yield Grade = 2.5

Adjustment for REA = -0.7

Adjustment Factor = -0.2

Final Yield Grade = 1.6

A yield grade is expressed as a whole number; any fraction of the number is dropped. In this example the equation results in a yield grade of 1.6, the final yield grade is 1. It is not rounded up.

Yield grades 2 and 3—usually expressed as Y2 and Y3—are generally in greatest demand by the meat industry. Y1 carcasses are fewest in number and typically do not have enough finish to grade USDA Choice. Y4 and Y5 carcasses are generally over finished, less desirable and often discounted.

Yield grade should not be confused with carcass “yield” and should not be confused with quality grade.