EVALUATION OF WHEAT MIDDLINGS AS A SUPPLEMENT FOR BEEF-COWS GRAZING NATIVE WINTER RANGE WITH DIFFERING FORAGE AVAILABILITIES

We conducted two studies to compare wheat middlings as a low-protein, highly digestible fiber supplement to soybean meal and corn-soybean me al supplement for cows grazing winter range. In two 60-d winter grazin g trials (December to February) cows (BW 500 kg) were allotted by age and weight to a 2 x 4 factorial with two forage availabilities and fou r supplements. Cows received either soybean meal (SBM), corn-soybean m eal (CS), low wheat middlings (LWM), or high wheat middlings (HWM). Th e SBM and LWM supplements were formulated to provide the same daily CP , and CS and HWM provided the same daily CP and ME. In a 4 x 4 Latin s quare, four ruminally fistulated steers (BW 765 kg) received the same supplements and had free access to mature prairie hay. Cows grazing th e high forage pasture gained more (P < .01) weight than cows grazing t he low forage pasture. Cows supplemented with HWM gained less weight ( P = .05) than cows supplemented with a similar amount of CP and ME fro m CS. Weight change of cows receiving SBM or LWM was similar. Increasi ng the amount of wheat middlings from LWM to HWM increased weight chan ge (P = .04). In Exp. 2, SBM and LWM: had similar total digestible DMI (DDMI). Steers supplemented with CS had higher total (P = .08) DDMI t han HWM. Supplementation with HWM resulted in lower total (P = .02) DD MI than LWM. Response to SBM and LWM was similar. The CS and HWM resul ted in beneficial performance responses as well as increasing the leve l of wheat middlings from low to high.