In recent years, there has been a marked shift in the percentage of beef carcasses in the three Yield classes with a sharp decline in the highest "Yield 1" class and a corresponding increase in the percentage of "Y 2" and " Y 3" Carcasses. This is not a positive development and the accompanying table analyses the impact that lower yields have on saleable beef yield.
According to the present grade regulations a Y-1 carcass is one with an average closely trimmed lean meat yield of 59% or higher and the upper limit recognized by those regulations, and by the Graders' Rule, is 65%. A Y-2 carcasses has a closely trimmed lean meat yield of 54 to 58% and a Y-3 carcass has a lean meat yield of 53% or less.
The closely trimmed lean meat yield is considered valid from a scientific standpoint but is less relevant in the trade than is "saleable yield" which more closely describes the product as sold at retail. The accepted average "retail yield" for purposes of estimating per capita disappearance, or consumption, is 73%.
In the accompanying table I have converted the current yield estimates from the closely trimmed lean meat basis, upon which the yield class is now estimated in the present grade standards, to a more practical and meaningful “retail yield basis” upon which per capita disappearance is based. The present grade standards specify that the yield of closely trimmed lean ranges from a low of 49% to a high of 65%. Though this is a reliable range based on good science it has the disadvantage of creating in producers minds the false supposition that this is the range of saleable beef content.
Recognizing that the only other component of a beef carcass is bone, including small amounts of connective tissue or sinew, which makes up a relatively constant percentage of the carcass one can conclude that any increase or decrease in the proportion of fat in a carcass must be associated with an equal and opposite change in the proportion of lean meat.
Thus, the retail yield of a carcass can easily be computed as is done in Table 1 table, as follows:
Under the Lean Meat Yield Column, we can see that the mid-point of the lean meat yield range is 57.5%.
The average retail yield of 73%, which is the accepted average retail yield of a beef carcass for per capita disappearance purposes, is set under the Retail Yield Column, adjacent to the average lean meat yield.
One can then approximate the range of retail yield by ratio calculation, the results of which are shown under the Derived Retail Yield Column where we see a range from a low of 62% to a high of 82%
Having made this conversion from lean meat yield to a retail weight basis one can next work out the average retail yield and the average fat content fat content of beef carcasses in any year.
In Table 2 the years 2005 and 2015 are compared. In the first two columns, the percent of carcasses that Graded Yield Class 1, 2 and 3 are shown. The appropriate weighted average steer and heifer carcass weights are set out in the following 2 columns. I then calculate the saleable beef yield by, for example, multiplying the percent of Y1 carcasses in 2005 (0.65) by the 2005 average Carcass weight (761 lbs) and that multiplied by the estimated average saleable yield of Y1 carcasses in (78.7% or 0.787) all of which results in 389 lbs. (0.65 x 761 x 0.787=389.3).
Under the Beef Yield 2005 Column heading, the calculation reveals that the contribution of the average Y-1 carcass to the over all average retail yield of 578 pounds was 389 pounds in 2005 compared to 267 lbs in 2015. Despite significantly heavier carcass weights in 2015 the sharply lower proportion of Y-1 carcasses in 2015 lowered the retail yield contribution of Y-1 carcasses. One can also see the increased contributions of the lower yielding Y-2 and y-3 carcasses in 2015 compared to 2005 under the corresponding Saleable Beef Yield Columns.
In total the average retail yield of all fed carcasses in 2005 was 578 lbs. and the average retail yield percentage was 75.9%. By comparison the average retail yield in 2015 was 606 pounds but the retail yield percentage was reduced to 73.4%.
In working out how much extra fat is left after normal retail cut out procedures are completed one must take account of the bone that was also removed from the carcass. Prior to processing, the bone component of the carcass is about 15% but in normal processing procedures some bone remains in roasts, ribs and steaks. In this exercise the assumption is made that 7.5% of the retail yield is bone meaning that the other 7.5% was removed.
Having taken account of the bone content of the retail yield, one can determine the extra fat that was removed to arrive at a standard retail product. This is done by subtracting from the hot carcass weight a normal retail yield and the estimated bone content removed in the process.
Overall the results are that the fat content of the average carcass was 15% higher in 2015 than in 2005 but the average retail yield declined only 3.3%. While this may seem counter intuitive it makes perfect sense when one realizes that fat does not “replace” lean. The physiological tendency is that cattle destined for slaughter grow first, lay on muscle next and fatten last. Since the primary determinant of Yield is fat cover, it is clearly apparent in this data that most Y-2 and Y-3 carcasses would have had a higher retail yield if slaughtered earlier.
These estimates are necessarily imprecise because the estimate of saleable meat yield remains imprecise. However, one can be certain that saleable meat yield, estimated in the Derived Meat Yield Column of Table 1 is directly comparable to the closely trimmed lean meat content estimated in the Lean Meat Yield Column of the same table.