Quality of forage stockpiled in Wisconsin

Abstract

Stockpiling forage is a commonly used method to extend the grazing season in the southern U.S.A. However, there is little data on stockpiled forage in the upper Midwest. This study was conducted to determine the quality changes of 7 stockpiled cool-season grasses [early and late maturing orchardgrass, Dactylis glomerata L., quackgrass, Elytrigia repens (L.) Desv. Ex. Nevski, reed canarygrass, Phalaris arundinacea L., smooth bromegrass, Bromus inermis Leyss., tall fescue, Festuca arundinacea Schreb., and timothy Phleum pratense L.], with and without N fertilizer, in Wisconsin. Forage was sampled at 3 offseason dates at 3 sites. To determine if N improved forage quality, 4 N-fertilizer treatments were imposed: 0 or 67 kg N ha(-1) applied at start of stockpiling and 2 treatments totaling 168 kg N ha(-1) applied in the fall and spring. Over winter, crude protein (CP) decreased from 116 to 107 g kg(-1), neutral detergent fiber (NDF) increased from 594 to 667 g kg(-1), acid detergent fiber (ADF) increased from 367 to 435 g kg(-1), and in vitro organic matter digestibility (IVOMD) fell from 734 to 655 g kg(-1). Nitrogen fertilizer improved CP in most environments but generally did not affect IVOMD, NDF, or ADF. Smooth bromegrass and quackgrass ranked highest in CP concentration and tall fescue ranked lowest. Timothy and late-maturing orchardgrass ranked highest in IVOMD while quackgrass and reed canarygrass consistently ranked lowest. Quality of all stockpiled forage studied can maintain livestock such as beef cattle or dry dairy cows over winter if the forage is accessible and adequate animal stocking density is maintained.