Where does corn fit in Western Canadian feedlot diets?

Corn acreage is expanding across Canada. There are about 25 acres of corn for every acre of barley in Ontario and Quebec, where temperatures, daylength and moisture allow predictable corn yields and feed quality. There are around eight acres of barley for every acre of corn in the prairies, although ambitious breeding efforts are underway to develop short-season corn varieties and production strategies to suit Western Canada’s more challenging climate.

Corn can be ensiled as ground, high-moisture corn (a high-starch energy source), or as whole-plant silage (a moderate energy source of fiber). It can also be ensiled as snaplage (the entire chopped ear of the corn, including the shank, cob, husk and grain), which lands somewhere in the middle.  A team of researchers led by the University of Saskatchewan’s Greg Penner ran a trial using these different forms of corn to partially replace barley in feedlot finishing diets (Short-season high-moisture shelled corn, snaplage, or corn silage as a partial replacement for dry-rolled barley grain or barley silage in western Canadian beef cattle finishing diets; dx.doi.org/10.1139/CJAS-2023-0032).

What They Did

After backgrounding on the same diet, a total of 320 crossbred steers (1,164 lbs) were fed one of four finishing diets in a small pen trial (10 head per pen) in 2020 and 2021. The four diets were designed to find out what would happen when CDC Austenson barley silage and barley grain were replaced with Pioneer 7202AM dent corn silage, high moisture corn grain, or corn snaplage.

The control diet contained 10% barley silage and 88% rolled barley (rolled to a processing index of 65%). The second diet replaced the barley silage with 10% corn silage, along with 88% rolled barley. The third diet contained 10% barley silage and equal amounts (44% each) of rolled barley and ground high-moisture corn. The fourth diet contained 20% corn snaplage to entirely replace the barley silage and lower the rolled barley grain content to 77%. This ensured the dietary starch concentration was similar to the control. The rest of the diet was limestone, urea and a mineral/vitamin supplement. Steers were slaughtered after 99 (Year 1) or 72 (Year 2) days on feed. Live weights, average daily gain, feed intake, gain:feed, fecal starch content, liver abscesses and carcass data were measured.

What They Learned

Growth performance: Dry matter intakes, finished weights, average daily gains and gain:feed of steers fed the standard barley-based control diet were not statistically different from the steers fed any of the three corn diets. While fecal starch was very low in this study, fecal starch content was higher in the steers fed barley and high-moisture corn (2.2 vs. 1.4%) than the barley-based control diet.

Carcass measurements: Steers fed the barley and high-moisture corn diet had statistically heavier hot carcass weights (895 vs 884) and higher dressing percentages (59.7 vs. 59.0) than the barley-based control diet. This translated into carcass-adjusted final live weights (1,508 vs. 1,486 lbs) and average daily gains (4.2 vs. 3.9 lbs/day) that were greater than the steers fed the barley-based control diet. This suggests that the higher starch level of the barley and high moisture corn diet (56 vs. 52% in the barley-based control diet) was enough to offset the starch lost in the feces while still promoting greater carcass weight. Neither the corn silage nor the snaplage diet differed from the barley-based control diet. There were no differences in yield or quality grades.

Liver abscesses: Overall, proportions of minor or severe liver abscesses were the same across all four diets (74%). Severe liver abscesses were less common in steers fed the barley grain and snaplage diet than in steers fed the barley-based control diet (10% vs. 26%). This was attributed to the higher “physically effective fiber” content in the snaplage diet (5.3% vs. 4.5% in the barley-based diet) that may have helped maintain rumen health and moderate rumen pH.