Reviewing literature on bison and nutrition

I'm going through the old literature on bison...not that there is much new literature.

One thing I still haven't found is whether bison gain weight better with low-quality forage than cattle.

The feeding trials on these are often suspect because bison don't like to be penned up. So, part of the problem is the wrong types of studies have been run. Another problem is that they don't push the nutritional envelope hard enough, e.g. feeding the animals 5-6% protein.

The question that evolves parallels the C-S debate in plants. Are cattle better at putting on weight than bison at all nutritional levels while bison just are better at tolerating stresses? Or do bison actually grow better on low-quality diets?

We know bison are better adapted to cold. They are thermoneutral down to -40°C. Cattle (like Hereford) are thermoneutral down to about -5°C.

We also know bison drop their metabolic rate by half in the winter.

They just don't need to eat much. They also seem to have better digestive efficiency than cattle. What they consume gets digested to a greater degree than what cattle consume.

But the definitive study that shows a nutritional niche still hasn't been found.

It's a bit frustrating this work hasn't been done and isn't slated to be done any time soon.

When we don't have the basics, it's hard to get at the more complicated questions...


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some notes for me...

Schaeffer et al. 1978.

--longer retention time than cattle.

--greater digestive efficiency (food is digested to a greater degree).

--greater nitrogen absorption from food.

Keith 1981

--when fed a diet higher in N, there are greater concentrations of urea in their blood, saliva, and urine

Rutley and Hudson 2000

--during the winter, bison take in about half the energy they do in the summer.

--food remains in the digestive system for twice as long in the winter as summer (46 vs. 24 h).

--when it’s snowy, bison intake rate drops a lot. 

Christopherson et al. 1978.

--stuck bison, yak, Scottish Highland, and Hereford calves in a freezer (20°C, 0°C, and -30°C).

--The metabolic rate of bison at -30°C was the lowest as other animals increased their metabolic rate when exposed to extreme cold. 

--Authors estimate that bison are thermoneutral below -40°C. In contrast, Hereford were good down to just -3°C in March.

Hawley et al. 1981.

--bison digest their food better than cattle (Hereford).

--during the summer, dry matter intake was 1.6% of body mass.

Galbraith et al. 1998

--bison switch on metabolically by April

--the digest their food more efficiently than deer or wapiti

--they also produce more methane

Koch et al. 1995.

--bison don’t gain weight at a higher rate than cattle on a low-protein diet

--bison don’t like to be penned in feeding trials like these, which may reduce weight gain.