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Cattle Grazing Blue Grama Rangeland II. Seasonal Forage Intake and Digesta Kinetics

1985; University of Arizona; Volume: 38; Issue: 6 Linguagem: Inglês

10.2307/3899749

2162-2728

F. T. McCollum, M. L. Galyean,

Ruminant Nutrition and Digestive Physiology

Four field trids were conducted from early August to iate October, 1982, on blue gramr (Bouteloua gracilis) nngeiand in south-central New Mexico, to examine reiationships among grazing season, forage intake and digestive function in beef steers @OS Luurus~.Organic matter intake decihted from 24.0 g/kg body weight (BW) in early August to 17.4 g/kg BW in late September and then increased to 20.9 g/kg BW in the early dormant season (iate October).From early growing season to early dormancy, diet digestibility and passage rates decreased while retention time of digesta in the rumen increased.Rate and extent of in vitro organic matter disappearance were 66.5,6.7;63.1,6.7;51.6,4.8;and47.9%, 5.6%/hour in early August, iate August, late September and iate October, respectively.Fhdd and partfcuiate passage rates (%/hour) were 24.9,4.6,12.7,3.9,11.1,3.7; and 10.5,3.5,respectiveiy, for the same periods.Retention of particulate digesta varied from 26.1 hours in the early growing season to 34.3 hours in early dormancy.Gastrointestinrri fill gradually increased as season progressed.Results suggest that maintenance of a diverse plant community, containing not only de&able grasses but also palatable forbs, may allow cattle to maintain a higher level of nutrient intake during periods of grass dormancy.