There is probably no symbiotic relationship more protracted than that between the feedlot and packing industries. The primary reason being the fact that we have a grading system that keeps us locked into a commodity-based marketing system.
While there are a few alliances trying to compete on a quality basis, mainstream packers must compete on price. If they are to sell cheaper than their competition, then they must also buy cheaper.
In order to do this, many packer buyers resort to accentuating or exaggerating the negative. A constant irritation source for feedlot managers, nutritionists often get drawn into the adversity when a particular product or feed additive is singled out as a source of discount. Virtually every new product has at one time or another been criticized by packer buyers as the "reason" cattle must be bid lower.
Ionophores Are A Positive The reality is that some products are actually a positive. Ionophores, for example, can actually improve yields. The most commonly used ionophore, Rumensin reduces intake. This translates into reduced fill - which on a liveweight basis improves the yield.
In truth, there is only one type of product that is a negative. From the 1950s, early research with DES (diethyl stilbesterol) indicated that implants can reduce intramuscular fat or marbling. They also reduce internal fat (which is a positive), but the reduction in marbling has been the focus.
Beginning in the '90s, the advent of implants containing trenbolone acetate (TBA) became a lightning rod for packer buyers. Implants containing TBA will consistently reduce marbling, which can have a variable effect on grading.
If cattle are well into the Choice grade, there will be little or no reduction in "grading." If, on the other hand, the cattle have a genetically low propensity to marble and are borderline at the Choice grade, the reduction in "grading" can be substantial.
Some packers were genuinely panicked and had sincere misgivings about TBA-implanted cattle. That prompted several research studies to definitively detail the effect on grading. The data indicated that, on average, a TBA implant will reduce visible marbling about 7-8%. Grading reduction runs from virtually no reduction to as high as 20% (for crossbred "plain" cattle).
On occasion, I have had to meet with packers to discuss implant protocols. One aspect of TBA implants I always try to point out is the positive effect on ribeye size.
Every study conducted in the last 10 years has shown TBA implants increase ribeye size a full 10%. It's my belief that TBA implants don't really reduce marbling, so much as we get the same amount of marbling in a larger ribeye.
Confirmation From Oklahoma State Recently, an Oklahoma State University study* proved that statement correct. Researchers took steaks from TBA-implanted and non-implanted cattle and chemically analyzed them for fat.
While they did find differences in the types of fatty acids, the total amount of fat between the TBA-implanted and non-implanted cattle was virtually the same. The only real variable was the amount of muscle in those steaks. The TBA-implanted cattle (as every other research study has shown) had significantly larger steaks.
A 10% larger loin has to have economic value. Yet packers seem to totally ignore this aspect of TBA implants. They seem to prefer to focus on the negative.