Heifer vs. Steer Carcass Performance
There has been discussion and speculation amongst Wagyu producers as to the carcass performance of heifers compared to steers. For meat animals, heifers are generally less desirable, and often discounted, compared to the price of steers. Reasons given typically include the assumption that heifers gain less in the feedlot and reach a lower finished weight, that heifers have smaller ribeye and other relatively more expensive loin meats, and that the yield grade is lower for heifers compared to steers. Data from progeny tests helps to shed some light on this matter, at least with respect to carcass data.
The data from 658 F1/50% Wagyu animals harvested as part of nine progeny tests completed (animals harvested) in 2021 and 2022 was evaluated to determine the differences in hot carcass weight (“HCW”), ribeye size (eye muscle area, or “EMA”) and USDA method (1-5) yield grade (“YG”) between steers and heifers.
The animals within each progeny test group were all:
- sired by either a registered 100% fullblood Wagyu bull or a 98%+ Wagyu genetics homozygous polled Wagyu bull;
- out of a Black Angus or Red Angus female from a single-producer consistent cow herd;
- born and raised on the same producer ranch;
- born within a short period (roughly 2-months);
- weaned within a period of a few days on the same producer ranch;
- entered the feeding program at the same feedlot on the same day where they were fed to achieve an F1/50% Wagyu marbling level; and
- were harvested at the same processing plant on the same day.
51.7% of the 658 animals were conceived by an artificial insemination (“AI”) breeding and 48.3% percent were conceived by natural cleanup bull service (“NS”), as determined by DNA parent-verification of the animal’s sire. Animals conceived by NS breeding were determined to be approximately 3% younger at harvest (and therefore weighed less) compared to AI breeding animals conceived and born earlier, and therefore, the HCW of animals conceived through natural breeding by a cleanup bull were adjusted by 3% to make such NS-conceived animals comparable to the older AI-conceived animals since if the NS-conceived animals had been allowed to continue to grow to reach the same age they would have become larger.
All steers in the progeny tests were castrated at a young age, either before or at weaning. All heifers were unspayed.
HCW was determined by the use of a certified scale to weigh each carcass at the processing plant. EMA and YG were determined at the 12th-13th rib using an E+V Technologies VBG2000 carcass camera system installed at the processing plant.
The results showed the following:
- Average HCW for heifers was 5.7% lower at 942.8 lbs. (427.65 kg) compared to steers, which weighed 1,000.3 lbs. (453.73 kg).
- Average EMA for heifers was 1.16% lower at 13.65 sq. in. (34.671 sq. cm) compared 13.81 sq. in. (35.077 sq. cm) for steers.
- Average YG for heifers was 4.21 compared to 4.20 for steers.
Some interesting observations from this data:
- HCW was lower for heifers compared to steers, but at only 6.0% lower, the difference was not as substantial as some might expect.
- And the EMA reported is the raw measurement, not adjusted for HCW, so heifers actually had a higher ribeye size to HCW ratio, and since the percentage difference in EMA was lower than the percentage difference in HCW, the result is that for each increment of HCW that a meat animal buyer purchases, the buyer actually gets more of the relatively higher value ribeye meat.
- YG was very similar for heifers (4.21) compared to steers (4.20), which is contrary to the conventional thinking that heifers put on more fat cover and have a worse yield grade compared to steers.
- Heifers were unspayed. It is well established that spayed heifers perform better in a feedlot environment gaining better as compared to unspayed heifers. This is generally assumed to be because unspayed heifers are cycling approximately every 21 days during the feed-out period, expending energy and reducing weight gain. Since all of the heifers in these progeny tests were unspayed, results for HCW would have been better for heifers compared to steers if the heifers had been spayed. And if spayed heifers gain more weight, some of such weight gain would also result in increased ribeye size, and would have thus made the EMA heifer results better than reported here.
- Buyers of meat animals or carcasses typically pay for the purchase based upon either live weight (“LW”) or HCW, and the price of heifers is often discounted compared to the price for steers. This is largely because it is assumed that heifers will not perform as well in the feedlot, and that even when finished animals (or even carcasses) are purchased, that heifer EMA (and other relatively higher value loin meats) will be smaller for heifers compared to steers. But because the EMA/HCW ratio is actually better for heifers compared to steers based upon this data, and because the purchase is based upon weight, a heifer carcass should perhaps be worth more compared to a steer.
Based upon these results, it seems that the famed Matsusaka Beef program, which is one of the top three Wagyu beef brands in Japan, and which produces some of the most expensive and sought-after Wagyu beef in Japan, might have something other than pure beef quality going for them, since all of their beef is produced from heifers.
One caveat for consideration is that for purchases of feeder calves yet to be finished, the amount of feed consumed for each increment of weight gain (feed conversion) varies from animal to animal, and it is possible that heifers convert feed less efficiently compared to steers. Feed conversion was not measured in these progeny tests. But for the purchase of a finished animal, ready for processing, this would make no difference.
