Seasonal Changes in Herbage and Cattle Diets on Sandhill Grassland

Abstract

The chemical composition and dry matter digestibility of clipped plant species, total herbage, and actual and simulated cattle diets were studied on sandhill grassland in eastern Colorado during the growing season and after dormancy. Clipped plants declined in percent protein and digestibility and increased in other chemical components with advanced maturity. Marked differences in chemical composition were evident among species in early summer, but minimal by winter. Actual cattle diets and those simulated from hand clipped plants were similar in chemical and digestible dry matter composition during each sampling period. In early summer, cattle diets were considerably higher in quality than total herbage but this difference became progressively smaller later in the summer. During dormancy and after weathering chemical composition and dry matter digestibility of herbage and of the cattle diets were essentially the samk. Cattle grazing native grasslands select their diet from plants which are continually changing in chemical composition and digestibility. Because cattle prefer leaf tissue over stem tissue, young growth over old growth, and green material over dry material, their diet is generally higher in quality than total herbage available. In the present study, seasonal changes in chemical and botanical composition and changes in nylon bag dry matter digestibility of total herbage and of actual and simulated diets of cattle grazing sandhill grassland were determined. Chemical and digestibility changes which occurred in major forage species through the year were also studied. This paper is a part of a broad study in grassland nutrition; l A contribution from W-94 Regional Project on Range Livestock Nutrition. Scientific Series Paper No. 1632, Colorado Agricultural Experiment Station, Fort Collins. We thank D. N. Hyder, R. M. Hansen and G. M. Van Dyne for their suggestions in this research and K. L. Knox, C. L. Streeter and R. E. Bement for their constructive reviews of the manuscript.

The “Foliage is the Fruit” hypothesis:Buchloe dactyloides (Poaceae) and the shortgrass prairie of North America

“…Both species can be highly palatable and of excellent forage quality. Some ofthe buffalograss individuals ofour research had 14% crude protein in their leaves, and blue grama may also have up to 15% crude protein and be the dominant species in cattle diets (Wallace, Free, and Denham, 1972). Indeed, these protein levels exceed those of the fleshy fruits of bird-disseminated plants (Stiles, 1980;Johnson et aI., 1985).…”

“…The female inflorescences ofthose species dispersed via adhesion or wind (Davidse, 1987) are characterized by long scabrous awns, sharp-pointed shorter awns, or numerous scabrous awns (Table 2). From our collective years of experience and from observations on other grasses (Cook, Stoddart, and Harris, 1956;Reppert, 1960;Wallace, Free, and Denham, 1972;Heady, 1975;Anderson, 1985;Ring, Nicholson, and Launchbaugh, 1985), we would expect such inflorescences to be unpalatable and avoided by herbivores at seed maturity. If ingested, the seeds of these species have almost no protection from digestion (only Opizia has a fertile lemma classed as indurate), and most grass seeds not enclosed in indurate bracts suffer high mortality (W. R. Ocumpaugh, Texas Agricultural Experiment Station, Beeville, TX, personal communication).…”

Nutrient content and phenology of cool‐season grasses of Peru*

“…IVDMD values for cool-season grasses of the Peruvian Andes generally were higher than for warm-season grasses of the southeastern United States (Lewis et al, 1975). Within-species comparisons show that 5. brachyphylla is higher in digestibility than that determined for S. comata (Wallace et al, 1972) and S. viridula in the USA (Kamstra, 1973). Digestibility for the genus Festuca was similar to values from Wales and the southern United States (Moore and Mott, 1973).…”

Steer nutritional response to intensive-early stocking on shortgrass rangeland

“…Acid detergent fiber, ADL, and cellulose decreased across time during the last half of the season-long stocking grazing season (P = 0.02, 0.10, and < 0.01, respectively, Table 3). Wallace et al (1972), Vavra et al (1973), and reported that cell wall components generally increased as vegetation matured. The only exceptions were that Vavra et al (1973) all treatments.…”