Effects of Forage Management on the Nutritive Value of Stockpiled Bermudagrass

'Common' and 'Tifton 44' bermudagrass [Cynodon dactylon (L.) Pers.] located near Fayetteville and Batesville, AR, respectively, were chosen to evaluate the effects of stockpiling initiation date (August or September), and N fertilization rate (0, 37, 74, or 111 kg N ha-1) on the nutritive value of fall-stockpiled bermudagrass. At the Fayetteville location, there were initiation x harvest date interactions for acid detergent fiber (ADF, P = 0.003), hemicellulose (P = 0.003), cellulose (P = 0.0003), lignin (P = 0.007), and crude protein (CP, P = 0.008) in 2000, and strong interactions (P < or = 0.001) for all response variables in 2001. Generally, neutral detergent fiber (NDF), ADF, cellulose, and lignin increased over harvest dates for both initiation dates in 2000, although increases for lignin were only numerical (P > 0.05) for the September initiation date. Similar responses were observed for the August initiation date in 2001, but fiber components for the September 2001 initiation date declined over time because of contamination by other winter-annual species. For August initiation dates in 2000 and 2001, in vitro organic matter disappearance (IVOMD) declined linearly (P < or = 0.002) over harvest dates, reaching respective minima of 330 and 361 g kg-1. At the Batesville site, an N fertilization effect (P < or = 0.017) was observed for NDF, ADF, and CP in both 2000 and 2001. A similar effect was observed for lignin (P = 0.001) and IVOMD (P < 0.0001) in 2000, and for cellulose (P = 0.0004) during 2001. Fertilization with N at the initiation of stockpiling generally reduced fiber components, and increased CP; however, IVOMD was increased for 2000 only. As observed for the Fayetteville site, most fiber components increased over harvest dates, while IVOMD declined concomitantly. Generally, the nutritive value of stockpiled bermudagrass declines between mid-October and mid-December, and spring-calving beef cows in the Upper South may need to be supplemented with energy to maintain body condition in the late fall or early winter.