Effects of season and diet, including costs, on feedlot performance of bison

Weaned bison bull calves were randomly assigned to four feedlot diets in a 4 treatment by 4 periods Latin square study. The feeding periods were 80 days long during spring, summer, fall, and winter. The four dietary treatments were identified based on major ingredients in each ration: 1) wheat screenings, 2) wheat middlings, 3) crambe meal, and 4) a commercial bison ration. Winter gains were lower than spring, summer or fall gains. Gains averaged 1.73 lbs. during spring, 1.38 lbs. during summer, 1.76 lbs during fall, and .38 lbs during winter. Average daily gains were 1.73 lbs for wheat screenings, 1.63 lbs for wheat midds, 1.53 lbs for crambe meal, and 1.61 lbs for the commercial diet during spring, summer and fall. Gains for wheat screenings were higher than for crambe meal with wheat midds and the commercial diet intermediate. There were no differences due to dietary treatment for dry matter intake, intake per unit weight, and dry matter per gain. Feed costs per pound of gain were $.54 for wheat screenings, $.73 for wheat midds, $.73 for crambe meal, and $.89 for the commercial diet. Bison in this study gained less in the winter than other seasons, consumed a variety of feeds with similar performance that resulted in highly variable feed cost per pound of gain.