|Mitchell, Robert - Rob|
Submitted to: Nebraska Beef Reports
Publication Type: Experiment Station
Publication Acceptance Date: 8/10/2007
Publication Date: 11/1/2007
Citation: Schwarz, A.K., Godsey, C.M., Luebbe, M.K., Erickson, G.E., Klopfenstein, T.J., Mitchell, R., Pedersen, J.F. 2007. Forage Quality and Grazing Performance of Beef Cattle Grazing Brown Mid-rib Grain Sorghum Residue. Nebraska Beef Reports, Pg. 35-35. University of Nebraska Extension MP91. Interpretive Summary: Brown midrib forage sorghum is currently in demand for silage and grazing because of its reduced lignin and improved forage quality. The brown midrib genes bmr-12 was crossed into a grain sorghum hybrid, and a beef grazing trial conducted following grain harvest. Grain yields from the two hybrids were statistically equivalent (119 BU/A). An increase from 0.75 lb to 1.23 lb in average daily gain (ADG), while grazing post-harvest residue, was associated with the addition of the bmr-12 gene to the hybrid. This increase in ADG was attributable to markedly improved fiber digestibility of the brown midrib hybrid. Incorporation of brown midrib genes into grain sorghum results in improved beef performance when grazing post-harvest residue.
Technical Abstract: The control (CON) grain sorghum hybrid AWheatland x RTx430 and its near-isogenic brown midrib counterpart (BRM) containing the gene bmr-12 , were utilized in a 72-d residue grazing experiment. Grain yield averaged 119 bu/ac and was not affected by treatment. ADG was increased from 0.75 lb in CON to 1.23 lb in BMR treatments over the grazing period. NDF digestibility increased 6-12% units in leaf fractions in BMR over CON. NDF digestibility decreased 2-12% units over the 72-d grazing period for both hybrids. Similarly, NDF digestibility of stem fraction increased 14-19% units in BMR over CON. NDF digestibility of the stem fractions remained constant, regardless of treatment, over time.