Response of Gestating Beef Cows to Limit-Fed Diets Containing Rolled Barley

Abstract

In the Northern Great Plains, barley grain may be a more economical source of energy than hay. An experiment was conducted at South Dakota State University Cottonwood Research Station to determine the efficacy of limit-fed, barley-based diets as an alternative to alfalfa hay for beef cows in late gestation. Ninety-six gestating, crossbred cows (age 3 to 11 years; average calving date of May 7) were stratified by age and weight and randomly assigned to one of 12 pens (8 cows/pen). Pens were randomly allotted to one of three winter feeding treatments (4 pens/treatment) from January 15 to April 10, 2003. Treatments were: 1) course-ground alfalfa hay (Hay; fed at approximately 1.6% of BW); 2) dry rolled barley replacing alfalfa hay at 29% of the diet dry matter (Low Barley; fed at approximately 1.4% of BW); and 3) dry rolled barley replacing alfalfa hay at 67% of the diet dry matter (High Barley; fed at approximately 1.2% of BW). All diets were formulated using the 1996 NRC computer model to provide for maintenance of body condition score. A supplement (0.5 lb/d) supplied adequate protein, minerals, vitamins, and 200 mg/hd/d of Rumensin. Rations changed monthly to account for changing cow requirements during late gestation. All diets were consumed within a two-hour period each day. Treatment means were separated using orthogonal contrasts (Hay vs. High and Low Barley; High Barley vs. Low Barley). Cows fed barley gained more weight than cows fed Hay (P \u3c 0.01; weight change of 79, 126, and 132 lb for Hay, Low Barley, and High Barley, respectively). Cows fed barley also gained more body condition than cows fed Hay (P \u3c 0.01; body condition score change of -0.10, 0.24, and 0.38 for Hay, Low Barley, and High Barley, respectively). There were no differences (P \u3e 0.10) in weight or body condition score change between Low and High Barley treatments. There were no differences between treatments in subsequent pregnancy rates (P \u3e 0.50). Rolled barley can be used to replace alfalfa hay in diets for gestating beef cows