Ruminal dry matter, crude protein, neutral detergent fiber and acid detergent fiber degradation parameter kinetics of Agropyron tauri, Agropyron trichophorum, and Bromus tomentellus.

This study was carried out to determine rate and extent of DM, CP, NDF and ADF degradation parameter kinetics of Agropyron tauri (ATA), Agropyron trichophorum (ATR), and Bromus tomentellus (BT). Forage samples were collected at the preflowering stage in spring by hand. Dried forage samples were incubated for 0, 6, 12, 24, 48, 72 and 96 h in the rumen of four Varamini wethers. Immediately after submersion of the 0 h bags of substrate into the ruminal fluid, all bags were removed and rinsed with an automatic washing machine. Bags were then freeze dried, weighed and analysed for chemical composition. Data were fitted to non-linear degradation model to calculate effective rumen degradation (ERD), and analysed (DM, CP, NDF and ADF degradability parameters of forages) using GLM proc of SAS (1996) as CRD design. Crude protein contents of ATA, ATR and BT were 123, 72, and 143 g/kg, NDF contents were 604, 638, and 451 g/kg and ADF contents were 348, 378 and 273 g/kg DM, respectively. There were differences (P<0.05) between effective DM, CP, NDF and ADF degradability of these pasture species. The ERD of DM, CP, NDF and ADF for ATA at rumen outflow rate of 0.05/h were 473, 630, 239 and 395 g/kg, for ATR were 393, 498, 331 and 337 g/kg, and for BT were 548, 760, 298 and 237 g/kg, respectively. Constant degradation rate of DM, CP, NDF and ADF for ATA were 6.0, 11.8, 2.7 and 5.7%/h, for ATR were 3.8, 8.6, 5.8 and 3.5 %/h and for BT were 4.2, 10.0, 1.8 and 3.7%/h, respectively. The differences between pasture species in the rate and extent of DM, CP and fiber degradation are likely to lead to major differences in forage intake, therefore these characteristics must be considered as main parameters in developing models and ration formulation of grazing ruminants. [ABSTRACT FROM AUTHOR]