Animal Industry Report

Extension Number

ASL R1998



Summary and Implications

A winter grazing experiment was conducted to evaluate the performance of bred 2-year old second-calf heifers grazing stockpiled forage at two stocking rates and two levels of supplementation during winter. Two 30- acre blocks containing 'Fawn' endophyte-free tall fescuered clover were each divided into four pastures of 6.25 or 8.75 acres. Hay was harvested from the pastures in June and August of 2003 and N applied at 40 lb/acre to initiate stockpiling in August. On October 22, 2003, twenty-four Angus-Simmental two-year old heifers, pregnant with their second calf, were allotted by weight and body condition score (BCS) to strip-graze for 147 d at 0.48 or 0.34 cow/acre and eight similar second-calf heifers were allotted to two drylots and fed tall fescue-red clover hay. Corn gluten feed was fed to maintain a mean BCS of 5 or 4.33 (9-point scale) for the high and low supplementation levels, respectively, or when weather prevented grazing. Mean initial forage yield was 3188 lb/acre and decreased 12.2 lb/acre/d in grazed areas of the pasture over 147 d. Mean seasonal concentrations of CP and IVDMD were greater (P < 0.05) in hay than stockpiled forage, while the concentration of ADF was greater (P < 0.05) in stockpiled forage. At the conclusion of winter feeding, animals grazing at the low stocking rate had greater (P < 0.1) BW than those grazing at the high stocking rate, and the BCS of grazing animals was 0.42 lower (P < 0.05) than animals maintained in the drylot. Animals in the drylot were fed 5944 lb/hd of hay. Mean amounts of corn gluten feed fed was 189.6, 19.1, 278.5, 16.9, and 5.2 lb DM/hd for the high stocking rate-high supplementation, high stocking rate-low supplementation, low stocking rate-high supplementation, low stocking rate-low supplementation, and drylot treatments, respectively, but did not significantly differ (P > 0.1).

Copyright Holder

Iowa State University