Quality and availability of tall fescue (Festuca arundinacea Schreb.) accumulated for fall and winter pasture was influenced by starting dates of accumulation, season of growth, and by the addition of legumes.

In 1975 and 1976, 60-day regrowths of tall fescue were evaluated (in vivo) for summer quality when fed alone and in 50:50 grass-legume mixtures to sheep. In 1975, 40-day old alfalfa (Medicago sativa L.) growth and in 1976, 60-day old red clover (Trifolium pratense L.) growth were used as legume treatments. In 1976, 60-day old orchardgrass (Dactylis glomerata L.) regrowth was fed alone and in a clover mix for comparison. Tall fescue was accumulated from mid-June, July, August, and September, fertilized with 112 kg N/ha in August, and fed in December to determine the effect of stockpiling date on in vivo quality. The effect of stockpiling date and N fertilization on yield, yield distribution, and chemical quality of fescue in winter were studied.

The total digestible nutrient (TDN) content of tall fescue in summer was variable between years (35.3% in 1975 and 52.2% in 1976). Alfalfa (54.9% TDN) was higher in digestibility in 1975 than tall fescue, but red clover (52.6% TDN) and orchardgrass (52.6% TDN) were similar to tall fescue in 1976. There were no significant differences in intake of the forages. There was a consistent, nonsignificant increase in the digestibility of grass-legume mixes over the average digestibilities of the component feeds.

The digestibilities of either summer grown tall fescue forage were considerably lower than those of the stockpiled tall fescue forages if accumulated from July, August, or September (60.2%, 61.6%, 61.6% TDN, respectively). June stockpiled forage (56.9% TDN) was lower in digestibility than the other stockpiling treatments but higher than for the summer grown tall fescue. In 1975, the DM intake (% bodyweight) of accumulated forage increased as stockpiling was delayed (June, 2.04% July, 2.41%; and August, 2.52%). In 1976, the digestibilities of all stockpilings were lower than in 1975. Digestibility increased as the accumulation periods were shortened from June to August (June, 52.0%; July, 56.7%; and August, 61.5% TDN) and then decreased for the shortest accumulation period (September, 54.5% TDN). The 1976 August accumulated growth was divided into top and bottom canopy strata; these strata (62.2% and 60.5% TDN, respectively) did not differ significantly in digestibility from the whole canopy (61.5% TDN). Intake in 1976 was not significantly affected by stockpiling periods or canopy strata.

The digestible protein (DP) content of tall fescue for all summer and winter treatments was highly correlated to the crude protein (CP) content.

There was a decrease in December dry matter (DM) yields as stockpiling and N fertilization was delayed from June to September. Generally, the best yield response for winter grazing occurred when N was applied at the date of stockpiling. Total yields decreased as stockpiling and fertilization was delayed. The highest total yields were obtained by fertilizing with N in June or July. Regrowth yields during summer were highest from early harvests but the yield distribution was shifted by N fertilization.

The winter quality of accumulated tall fescue increased as yields decreased with delaying dates of stockpiling and fertilization. Total nonstructural carbohydrates (TNC 88 % of DM) increased from 14.7% to 30.5% in 1975 and from 11.8% to 28.0% in 1976; CP content increased from 8.2% to 15.5% in 1975 and from 8.2% to 13.9% in 1976 when stockpiling and fertilization were delayed from June to September. However, the yield of TNC and CP decreased as DM yield decreased. The relative chlorophyl content increased in canopies with delayed stockpiling and fertilization. Fertilization with N increased forage quality and resistance to early winter freezing. Yield and quality of tall fescue in February was lower than but highly correlated to the December yield and quality.