A field evaluation study was made on eight pasture grass species, 'Latar' orchardgrass (Dactyl& glomerata L.), 'Fawn' tall fescue (Festuca arundinacea Schreb.), 'Manchar' bromegrass (Bromus inermus Leyss.), 'Regar' bromegrass (B. biebersteinii Roem and Schult.), 'Garrison' creeping foxtail (Afopecurus arundinacea Poir.), 'Meadow' foxtail (A. pratensis L.), 'Luna' pubescent wheatgrass (Agropyron trichophorum (Link) Richt.), and 'Greenar' intermediate wheatgrass (A. intermedium (Host) Beauv.). Three harvests of each species were analyzed for in vitro dry matter digestibility (IVDMD) for 1975,1976, and 1977. Fawn tall fescue and Manchar bromegrass had severely depressed IVDMD values in the second harvest of 1976 and both species and Regar bromegrass had low values for the third harvest of that year. The forages were analyzed for perloline alkaloid by a thin layer chrometography method and the depressed IVDMD values were found in the replicate samples containing perloline. The alkaloid could be toxic to livestock. Methods The eight grass species studied were 'Latar' orchardgrass (Dactylis glomerata L.), 'Fawn' tall fescue (Festuca arundinacea Schreb.), 'Manchar' bromegrass (Bromus inermus Leyss.), 'Regar' bromegrass (B. bierbersteinii Roem and Schult.), 'Garrison'creep- ing foxtail (Alopecurus arundinacea Poir.), 'Meadow' foxtail (A. pratensis L.), 'Luna' pubescent wheatgrass (Agropyron trichophorum (Link) Richt.), and 'Greenar' intermediate wheatgrass (A. intermedium (Host) Beauv.). These irrigated forages were established in the field at Cheyenne, Wyo., in the spring of 1974 as part of a large evaluation trial in 2.4 X 4.8 m plots. Two centimeters of water were applied to the grasses every 3 or 4 days. Each species was replicated twice. Ammonium nitrate was applied to the grasses each year near May 1 and July 1 at the rate of 76 kg N/ha.- Harvests were made each year when the grass was at boot or heading stage on the first crop and when regrowth was 20 to 30 cm tall on succeeding crops. Forage from each plot area was clipped, weighed, and subsampled. The subsample of green forage was placed in a drying oven within 1 hour after harvest and dryed at 65O C to determine dry matter production. The forage IVDMD for each of three harvests per year during 1975 thru 1977 was determined by a modified Tilly and Terry (Tilly and Terry 1963) method. The alkaloid concentration in the 1976 harvests were determined by a thin layer chromatography (TLC) method as follows: A l-gram sample of dried and ground plant material was mixed with 0.3 g of sodium bicarbonate and 2 ml of water in a small beaker. The mixture was stirred with a glass rod for 2 minutes. Ten ml of a CHCh/ MeOH (9: 1) solution was added to the mixture and stirred with a magnetic stirrer for 30 minutes. The mixture was then filtered and the filtrate was evaporated in vacua to a volume of 1 ml. The alkaloids were separated from other plant material by a silica gelTLC. Forty microliter aliquots were spotted and developed with the upper phase of a mixture of butanollacetic acid/water (4: 1:5). An iodoplatinic acid solution, used for visulization of spots, consisted of a mixture of 10 ml of a 5% platinum chloride, 5 ml of cont. HCl, and 240 ml of a 2% KI solution. Results and Discussion Festuca and Bromus species had significantly inhibited IVDM D in the second and third harvests of 1976 compared with other species in the study. While all grass species showed depressed IVDMD values for the first harvest of 1975, this was probably caused by the fiber content of the more mature forage compared with the re-growth of succeeding harvests of that year. During the study, severe inhibition of IVDMD did not occurr in Latar orchardgrass, Garrison creeping foxtail, Meadow foxtail, Luna pubescent wheatgrass, and Greenar intermediate wheatgrass. Therefore, IVDMD values were shown in Table 1 for a
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Nov 1, 2024
Evans Duah + 3
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