Yield and feeding of prairie grasses in east-central Alberta

Information on the yield of grasses as the plants mature is useful to optim ize grazing potential and quality hay production. The objectives of this st udy were to compare the yield and feeding value of 11 common prairie grasse s over 2 yearly cycles of growth and determine which of the grasses may req uire supplementation to meet nutrient requirements of grazing cattle. Dry m atter yield (DM), crude protein (CP), acid detergent fiber (ADF), calcium ( Ca), and phosphorus (P) values were obtained for brome (Bromus inermis [L.] ), creeping red fescue (Festuca rubra [L.]), crested wheatgrass (Agropyron cristatum [L.] Gaertn), intermediate wheatgrass (Agropyron intermedium (hos t) Beauv), meadow foxtail (Alopecurus pratensis [L.]), orchardgrass (Dactyl is glomerata [L.]), pubescent wheatgrass (Agropyron trichophorum Link. rich t), streambank wheatgrass (Agropyron riparium Scriba & Smith), slender whea tgrass (Agropyron trachycaulum Link Malte), tall fescue (Festuca arundinace a Schreb), and timothy (Phleum pratense [L.]) at weekly intervals from June to September, in 1992 and 1993. Most grasses reached maximum yields at wee k 8 in 1992 (drought year) and week 12 in 1993 (normal year). Herbage mass yields (g/0.25m(2)) at week 8 in 1992 (highest to lowest yielding) were cre sted wheatgrass (235), intermediate wheatgrass(210), pubescent wheatgrass(1 73), brome(161), slender wheatgrass(152), meadow fox-tail(114), Tall fescue (110), timothy(101), orchardgrass(83), creeping red fescue(56), and streamb ank wheatgrass(50). Herbage mass yields pattern of the grasses in 1993 was similar to that in 1992 except for crested wheatgrass and brome which ranke d first and fourth in 1992 but ranked fifth and second, in 1993, respective ly. Quality declined in all grasses as they matured. The average Cg content of grasses declined from 24% to 13% in 1992 and from 21.5% to 12.1% in 199 3 but were adequate to meet crude protein requirements of growing, pregnant or lactating grazing cattle. The Ca levels in all grasses were adequate fo r all classes of cattle on pasture but the low P levels of 0.11% in both ye ars indicate that growing, pregnant or lactating cattle grazing on these pa stures would require P supplementation.