There appears to be no advantage to feeding bison the same high grain diet as cattle, says University of Saskatchewan researcher Greg Penner.
“Bison probably are not as good at tolerating a high grain diet as beef cattle,” he told the Canadian Bison Association annual convention in Regina.
It’s because their rumens produce a lot of acid when they consume a lot of starch. Problems occur if the rate of production is greater than the rate of removal.
He said bison can’t absorb the nutrients they need.
“We want lots of acid production to allow for a lot of nutrient availability, but if we go too far we actually compromise the animal and we start decreasing that acid absorption.”
Penner’s study arose from the fact that bison can take 246 to 413 days to reach a 950 pound slaughter weight. Feeding grain can improve consistency and reduce days on feed.
The study included 23 Plains bison bulls from Elk Island National Park and 23 beef bulls, placed in pens of three.
The animals were fed diets in which the ratio of barley increased over time. The study included backgrounding and finishing diets.
“We started them off consuming about 65 percent barley silage, 25 percent barley grain and 10 percent of a backgrounding pellet,” Penner said.
The bison ate this diet for seven days, moved to 55 percent silage and 35 percent grain for another seven days and then to 45 percent silage and 45 percent grain.
The finishing diet began the same, except for the use of a finishing pellet, and then changed every four days until, at 28 days, they were eating 10 percent silage and 80 percent grain.
“One of the major problems we saw was incredible variation in dry matter intake in our bison animals,” Penner said.
They ate less and didn’t consume more energy, even though they were provided with more energy in the feed.
The beef bulls overall consumed far more feed than the bison.
Rumen pH, measured by orally administered meters, found high pH values in bison during backgrounding and lower values during finishing. The cattle numbers were about the same for each diet.
“What this suggests to me is bison are having a lot more difficulty in terms of regulating rumen pH, especially as they start seeing high grain diets,” he said.
This could lead to rumen acidosis and liver damage when bacteria leak through a damaged rumen wall.
The study was short, at 45 days, and Penner said more work is required.
“The biggest thing we learned is we can’t raise bison like cattle and we saw a big reduction in feed intake as we moved those bison to high-grain diets,” he said.
“We did not improve performance. We did not reduce variation.”