Does corn test weight effect feedlot performance and carcass characteristics of cattle? North Dakota State University scientists decided to find out by allotting 144 crossbred steers (985 lbs.) to one of three dietary treatments:

  • Heavy test weight corn (HTC) — 53.7 lbs./bu.;
  • Medium test weight corn (MTC) — 46.9 lbs./bu.;
  • Low test weight corn (LTC) — 39.1 lbs./bu.

The diet was composed of 81% dry-rolled corn, 5% beet pulp, 5% mixed hay, and 9% supplemental ingredients, with the steers harvested after 66 or 82 days on feed.

Researchers reported no significant differences among treatments in final weight or average daily gain (ADG). The LTC steers tended to have higher daily dry matter intake (DMI) than HTC steers (27.3 lbs. vs. 25.4 lbs.), but there was no effect of treatment on feed conversion, which averaged 5.55 lbs./lb. of gain.

Apparent net energy for maintenance (NEm) and gain (NEg) were similar among treatments.

At harvest, carcass weight and marbling score didn't differ among treatments, but LTC carcasses tended to have smaller ribeyes than either MTC or HTC steers (12.74 vs. 13.49 and 13.46 sq. in., respectively). Treatments didn't differ in backfat thickness (0.45 in.) or KPH fat (1.96%). However, LTC carcasses tended to have greater yield grades compared to MTC or HTC carcasses (3.04, 2.80, and 2.73, respectively.

The authors concluded that, although steers fed the LTC diet had greater DMI, LTC is a suitable substitute for HTC.

(Larson et al. 2006. Midwest Section ASAS. Abstract 133).
— Michigan State University Beef Cattle Research Update, Summer 2006