ABSTRACT
Summary Nutritive value of 18 ryegrass (Loliurn multiflorum Lam.) cultivars was studied at Overton, Texas, during a 3-year period to determine the variation in protein content and neutral detergent fiber (NDF) of 9 diploid and 9 tetraploid ryegrass cultivars as influenced by season. Comparisons were also made within diploid and tetraploid cultivars. Samples for analysis were collected from forage variety tests for the growing seasons of 1976 to 1979. Ryegrass cultivars were drilled into conventionally tilled seedbeds prior to mid-September and fertilized at a rate of 67 kg/ha each for N, P2O5, and K2O. Additional N was applied in split applications in November and February for a total seasonal rate of 235 kg/ha. The forage was clipped to a uniform height of 5 cm with a flail-type harvester. Forage samples were oven dried and ground to pass through a 2350.42-mm screen. Plots were harvested four times during each of the first 2 years and five times in the third year. In 1977-1978 and 1978-1979, NDF and protein analyses were run on samples from 2 replications. All forage samples were analyzed for protein via the micro-Kjeldahl technique. Percentages of NDF were obtained via Van Soest extraction procedures. A seasonal increase in neutral detergent fiber (NDF) content and a decrease in protein percentage was observed. Differences in NDF were observed among cultivars and were most apparent during April and May. The differences probably were related to maturity levels of individual cultivars since earlier-maturing cultivars tended to have higher NDF levels. Tetraploids were lower in NDF, probably because they matured later than did the diploids. Protein levels decreased during the growing season from about 25 % in December to about 13 % in late May. Differences among cultivars and between ploidy levels were not significant for protein percentage.
