Effects of Level of Concentrate and Forage Availability on the Performance of Beef Cows Grazing Winter Range

Two winter grazing trials were conducted on consecutive years to determine the effect of level of concentrate supplement and amount of forage available on performance of cows grazing dormant winter range. Simmental x Angus cows were fed concentrate supplements containing combinations of corn and soybean meal at either high, medium or low levels. Supplements were formulated to provide .7 Ib of crude protein during year 1 and .51 Ib of rumen degradable crude protein in year 2. Two pastures with differing amounts of available forage were grazed each year. In year 1, the amount of available forage had a greater effect on body weight and condition score change than did level of concentrate fed. Cows receiving higher levels of supplement actually gained less weight. The interaction between level of supplement and amount of available forage showed higher levels of concentrate supplement may be more detrimental when amount of available forage is limited. The amount of available forage was considerably greater in both pastures the second year with cows gaining more weight on the high available forage pasture. Cows receiving higher levels of concentrate supplement gained more weight and body condition than those receiving lower levels of supplement. There was no interaction between forage availability and level of concentrate in year 2