Impact of different wheat milling by-products in supplements on the forageuse and performance of beef cattle consuming low-quality, tallgrass-prairie forage

Two experiments were conducted to evaluate the impacts on forage use and be ef cattle performance of incorporating divergent wheat milling by-products in a 30% CP supplement. The by-products were wheat bran (high fiber) and se cond clears (high starch). The by-products were added as 1) 100% wheat bran ; 2) 67% wheat bran, 33% second clears; or 3) 33% wheat bran, 67% second cl ears to constitute approximately 47 to 49% of the supplement. In Exp. 1, 90 Hereford x Angus cows (BW = 554 kg) grazing winter, tallgrass-prairie rang e were fed the supplement treatments (2.27 kg/cow daily) from early Decembe r 1997 until calving (average calving date = 3/11/98). Cumulative BW and co ndition changes from trial initiation through calving were not significantl y different among treatments. Similarly, significant treatment effects on c ow pregnancy rates as well as calf birth weights, ADG, and ending weights w ere not evident. In Exp. 2, 16 ruminally fistulated Hereford x Angus steers (BW = 484 kg) were blocked by weight and assigned to one of the same three supplement treatments or to a negative control (forage only). Steers had a d libitum access to tallgrass-prairie hay (76.4% NDF, 3.1% CP) and were fed supplement at the same rate (relative to BW) as the cows in Exp. 1. Forage OM, NDF, and digestible OM intakes were lower (P < 0.01) for the negative control than for supplemented steers but were not significantly different a mong the supplemented steers. Digestion of OM was lower (P = 0.03) for the negative control than for supplemented steers, although significant treatme nt differences were not evident among the supplemented groups. Digestion of NDF was not affected (P = 0.49) by treatment. Within the context of the am ount of supplemental protein offered, changes in the combination of wheat m illing by-products in the supplement did not affect cow performance or inta ke and digestion of low-quality forage.