FORAGE QUALITY, PRODUCTIVITY AND FEEDING VALUE TO BEEF-CATTLE OF QUACKGRASS (ELYTRIGIA-REPENS (L) NEVSKI) COMPARED WITH TIMOTHY (PHLEUM-PRATENSE L)

Field and animal feeding experiments were conducted in 1989 at the Sta tion agronomique de l'Universite Laval near Quebec City to compare qua ckgrass (Elytrigia repens (L.) Nevski.) with timothy (Phleum pratense L.) hay in terms of forage quality, productivity and feeding value. Ti mothy stands infested with 0, 50 or 100% quackgrass were cut at early heading and fed to Charolais X Simmental growing heifers. Quackgrass f orage contained more (P<0.05) crude protein (CP), and less neutral det ergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lign in (ADL) than timothy. The timothy-quackgrass mixture had a greater CP concentration, and similar NDF, ADF and ADL concentrations compared w ith timothy. Mineral composition, as measured by calcium (Ca), phospho rus (P) and magnesium (Mg), did not differ among forages. Quackgrass a nd the timothy-quackgrass stands yielded more dry matter than timothy stands. Feed conversion ratio tended to be better for timothy (8.5) th an for quackgrass (9.2) and quackgrass-infested timothy (9.3). Animal yield from quackgrass (309 kg gain ha(-1)) exceeded that from timothy (237 kg gain ha(-1)). Animal yield did not differ between timothy and quackgrass-infested timothy. Quackgrass may not be considered as a wee d in timothy forage destined for beef cattle production, as long as it does not interfere with cropping sequence or spread to cultivated cro pland.