Effects of Wheat Middlings on Utilization of Mature Prairie Hay by Steers

A digestibility trial measuring intake, digestibility, ruminal nutrient disappearance, and ruminal pH was conducted to determine the effects of wheat middlings on utilization of mature prairie hay. Treatments included supplements used in a previous winter grazing trial at the SDSU Cottonwood Research Station that were balanced to provide the following amounts of crude protein (Ib) and metabolizable energy (Mcal) per cow daily: 1) soybean meal .75 and 2.40, 2) low wheat middlings .75 and 4.76, 3) corn-soybean meal 1.50 and 9.40, and 4) high wheat middlings 1.50 and 9.40. These supplements were fed to the steers in proportional amounts based on BW75. Steers receiving the low wheat middlings supplement had similar hay and total diet intake but lower digestible dry matter intake than steers receiving soybean meal. High wheat middlings supplementation decreased hay intake and digestible hay and total diet intake compared to corn-soybean meal and low wheat middlings. The high level of wheat middlings and cornsoybean meal reduced ruminal pH at 4 and 8 hours post-supplementation. The high level of wheat middlings depressed overall ruminal disappearance of hay dry matter and NDF compared to the corn-soybean meal supplement and the low level of wheat middlings. This study indicates that wheat middlings may depress utilization of mature, low protein forages compared to soybean meal or corn-soybean meal supplements balanced to provide the same level of protein