The Effect of Season of Growth and Clipping on the Chemical Composition of Blue Grama (Bouteloua Gracilis) at Hays, Kansas

Abstract

The Effect of Season of Growth and Clipping on the Chemical Composition of Blue Grama (Bouteloua Gracilis) at Hays, Kansas NOEL R. RUNYON, Fort Hays Kansas State College, Hays Blue grama (Bouteloua gracilis) is one of the most important forage plants in the Great Plains grazing region. It is found over a much larger area than buffalo grass (Buchloe dactyloides) (Shantz, 1923). The proper use of this valuable forage plant can be determined most effectively if something is known concerning its chemical composition in various stages of growth and under various intensities of grazing. The purpose of this research was to determine both the effect of repeated clipping and uninterrupted growth on the chemical composition of blue grama. The constituents sought were moisture, dry matter, ash, calcium, phosphorus, fat, crude protein, crude fiber, and nitrogen-free extract (N-free-extract). RELATED STUDIES According to Hopper and Nesbitt (1930) the moisture content of the young, vigorously growing plant is much higher than at any other stage in the development of the plant. This was further substantiated by Lush (1933) who concluded that the moisture content lowered with the advance in the season. There have been some variations in different regions in regard to the ash content during the growing season. Lush in Louisiana and Hopper and Nesbitt in North Dakota found very insignificant ash fluctuations in hay and pasture grasses. Stoddart and Greaves (1942), however, found a tendency for the total ash content to decrease throughout the growing and late summer season in the rather arid regions of Utah. They found that phosphorus decreased quite noticeably while calcium remained practically constant. Morrison (1941) says that forage plants contain much more phosphorus and calcium in their early growth stages than in later stages. Stanley (1938) confirmed the tendency for calcium and phosphorus to decrease in range grass in Arizona through the season. An interesting study by Watkins (1937) reveals a daily need for twenty grams of calcium and ten grams of phosphorus per head in mature cattle in the New Mexico range country. In order that the need be supplied, the calcium should not fall below 0.25 per cent and phosphorus not below 0.12 per cent. Stanley has made the same observations on the grassland ranges in Arizona. Nearly all have observed a decrease in the percentage of total protein through the season in the common pasture grasses. These include Stoddart and Greaves from Utah, Lush from Louisiana, Hopper and Nesbitt from North Dakota, Shutt (1929) from Canada, Stanley from Arizona, and Dustman and Van Landingham (1930). Brown (1939) of Missouri found a correlation between temperature and the percentage of protein. The protein decreased slightly when the temperature was between 40? and 60? F. and increased when the temperature reached 70? to 100? F. These men just previously mentioned were fairly well agreed that the crude