By Dr. Roy BurrisClick here to see more...
It was 1974 and I had just started my career as a beef cattle researcher for Mississippi State University. I was part of projects on grazing systems and crossbreeding but was also starting a new project on finishing cattle in south Mississippi. We were in the process of building a research feedlot but I needed to get something going right away. Fortunately, at that time, finishing cattle on grass was receiving a lot of attention in the southern region. Since I had ryegrass and cattle, one of my first trials was “Finishing Steers on Ryegrass-clover Pastures with Supplemental Grain”. Some of the things that we learned then are still relevant 42 years later.
Steers were grazed for 150 days during the winter and received either (1) no grain, (2) one percent bodyweight (BW) of cracked corn throughout, or (3) cracked corn the last 64 days. Dr. Neil Bradley (UK) always said that it takes 20 bushels of corn to “finish” cattle. One percent BW for 150 days would be in that range. Grain fed calves did tend to marble better and have greater fat thickness and yield grades.
My first “problem” was that a local producer told my boss that cracked corn was too low in protein for the steers to gain. I patiently explained (nah, I didn’t) that since the ryegrass-clover was very high in protein, they needed energy to fatten – not protein. But I did learn that most producers are hung up on crude protein levels when buying feed and pay little attention to energy levels. That is still true today.
The steers (shown in the picture) don’t look much like cattle do now. These steers were not straight black or large framed. In fact they were harvested at 900 lbs.! Marbling is, to a large degree, a function of maturity. In other words, once a calve stops growing, it then begins to lay on external and, hopefully, internal fat (marbling). Thus, early maturing (smaller framed) cattle might work better for forage diets. Cattle on this trial averaged slight-plus marbling (enough to grade USDA Select plus). As I bred the cattle for more size and growth, it became more difficult to maintain marbling ability. We now look for those “outliers” that possess extra marbling ability.