PMID- 15956482 OWN - NLM STAT- MEDLINE DCOM- 20070913 LR - 20171116 IS - 1525-3163 (Electronic) IS - 0021-8812 (Linking) VI - 83 IP - 7 DP - 2005 Jul TI - Estimation of feeding value of four tropical forage species at two stages of maturity. PG - 1726-31 AB - The feeding value of four tropical grasses was assessed through voluntary intake and digestibility studies using yearling Brahman x British steers (average BW = 256 +/- 34 kg). The digestibility of OM was estimated using total fecal collection (TFC), in vitro OM digestibility (IVOMD), and by estimating fecal production using insoluble acid detergent fiber (IADF) as an indigestible marker. The four grasses consisted of bahiagrass (Paspalum notatum), limpograss (Hemarthria altissima), bermudagrass (Cynodon dactylon), and stargrass (Cynodon spp.). Grass was harvested at two stages of maturity (approximately 4 and 10 wk). Forages were ground (5 to 10 cm) and offered to steers ad libitum. Forage treatments were assigned randomly to steers over eight 28-d periods and repeated over two consecutive years. Total forage offered and refused was determined during a 14-d sample collection period. For determination of fecal output, steers were placed into metabolism crates for 7 d. Composited samples of forage offered, forage refused, and feces of each steer at each period were analyzed for DM, OM, NDF, ADF, IADF, IVOMD, and CP. All digestibility results were calculated on an OM basis. There were year x grass x maturity interactions (P < 0.01) for all measures of forage quality, except CP. Increased maturity resulted in a 37.8% decrease (P < 0.001) in CP concentration when averaged across all forages. Four-week bermudagrass contained the greatest (P < 0.05) concentration of CP compared with all other grasses at both maturities, except 4-wk stargrass. Bahiagrass IVOMD did not differ among 4- and 10-wk maturities in both years; however, the IVOMD content of both stargrass and bermudagrass decreased (P < 0.05) when these forages matured from 4 to 10 wk. Apparent OM digestibility, determined by TFC, was greater (P < 0.05) than OM digestibility determined by IVOMD and IADF for all forages except bahiagrass, for which IADF did not differ from TFC. In Year 1, OM intake (OMI) of 10-wk limpograss was less (P < 0.05) than all other 4-wk forages. In Year 2, voluntary OMI of 10-wk limpograss was less (P < 0.05) than all grass x maturity combinations, except for 10-wk bermudagrass. These data suggest that important differences exist in changes in nutrient quality associated with increased maturity in tropical forages. Among the forages assessed in this study, bahiagrass seems to better retain nutrient quality when maturing from 4 to 10 wk. FAU - Arthington, J D AU - Arthington JD AD - University of Florida-IFAS, Range Cattle Research and Education Center, Ona, 33865, USA. jdarthington@mail.ifas.ufl.edu FAU - Brown, W F AU - Brown WF LA - eng PT - Comparative Study PT - Journal Article PT - Research Support, U.S. Gov't, Non-P.H.S. PL - United States TA - J Anim Sci JT - Journal of animal science JID - 8003002 RN - 0 (Dietary Fiber) RN - 0 (Dietary Proteins) RN - 9005-53-2 (Lignin) SB - IM MH - Age Factors MH - Animal Feed/analysis/classification/*standards MH - Animals MH - Cattle/*physiology MH - Diet/standards/*veterinary MH - Dietary Fiber/analysis/metabolism MH - Dietary Proteins/analysis MH - Digestion/physiology MH - Eating MH - Least-Squares Analysis MH - Lignin/analysis MH - Male MH - Nutritive Value MH - Poaceae/chemistry/classification/*metabolism MH - Random Allocation MH - Seasons MH - Time Factors MH - Tropical Climate EDAT- 2005/06/16 09:00 MHDA- 2007/09/14 09:00 CRDT- 2005/06/16 09:00 PHST- 2005/06/16 09:00 [pubmed] PHST- 2007/09/14 09:00 [medline] PHST- 2005/06/16 09:00 [entrez] AID - 83/7/1726 [pii] AID - 10.2527/2005.8371726x [doi] PST - ppublish SO - J Anim Sci. 2005 Jul;83(7):1726-31. doi: 10.2527/2005.8371726x.