• Contrasts of esophageal-fistula versus bite-count techniques to determine cattle diets

      Ortega, I. M.; Bryant, F. C.; Drawe, D. L. (Society for Range Management, 1995-11-01)
      To understand how different techniques might affect diet estimates for cattle, the esophageal-fistula and bite-count techniques were compared using trained cattle. For the Texas Coastal Bend, bite-count was not as reliable a technique as the esophageal fistula. These techniques differed in estimation of forage classes and plant species in cattle diets. The esophageal-fistula technique was more accurate however, the bite-count technique may be acceptable if analyses are limited to only those plant species making up >2% of the diet.
    • Forage quality, intake, and digestibility of year-long pastures for steers

      Kloppenburg, P. B.; Kiesling, H. E.; Kirksey, R. E.; Donart, G. B. (Society for Range Management, 1995-11-01)
      Thirty-six weanling steer calves (avg wt = 174 +/- 14 kg) were grazed on either wheat, irrigated improved, or native rangeland pastures from December 1989 to December 1990. Irrigated improved pastures consisted of 2 cool-season [tall wheatgrass [Agropyron elongatum (Host.) Beauv.], tall fescue (Festuca arundinacea Schreb.) 2 warm-season [bermudagrass (Cynodon dactylon (L.) Pers.], bluestem (Bothriochloa ischaemum Keng.), and annual wheat. Wheat pastures were grazed from 13 December to 11 April. Warm-season pastures were grazed from 30 May (bermudagrass) or 27 June (bluestem) until 3 October. Cool-season pastures were grazed at other days during spring and fall seasons. Rumen evacuation procedures were used to evaluate forage quality and estimate forage intake during each grazing season. Winter rangeland pastures were lower in nutritional quality (based on protein and fiber contents) and in vitro organic matter digestibility (53 vs 85%, P < 0.05) compared to wheat pasture. During spring, rangeland pastures were still lower in protein and higher in fiber but in vitro organic matter digestibility (72, 73, 72%; respectively, for wheatgrass, fescue and rangeland) was similar (P = 0.70) for all forages. Rangeland and warm-season pastures were similar in quality during summer but rangeland pastures were higher (P< 0.10) in in vitro organic matter digestibility (65, 69, and 73%; respectively, for bermudagrass, bluestem, and rangeland). Rangeland pastures were again lower in quality and digestibility than cool-season grasses during the fall. There were no difference (P>0.10) in organic matter intake (% of body weight) during winter, summer, and fall season but during spring organic matter intake was greater (P < 0.10) for steers on rangeland pasture than for those on cool-season grasses.
    • Relative abundance and diet composition of Chacoan cavies in relation to range condition

      Rosati, V. R.; Bucher, E. H. (Society for Range Management, 1995-11-01)
      The relative abundance and dietary botanical composition of the Chacoan cavy (Pediolagus salinicola) was studied on sites of very good, good, and poor range condition in the Western Chaco, Argentina. Pellet count data showed that Chacoan cavy densities varied (P<0.001) among these areas. In both seasons, the highest number of pellets was found in the area of poor condition. This area was characterized by an absence of grasses, dense cover of a creeping fern (Selaginella sellowii), thorny shrubs and a scarcity of dicot herbs. In contrast, a decrease (P<0.05) in Chacoan cavy densities was found in the good and very good range condition areas, coincident with the increase of grass and forb cover. Fecal analysis showed that Chacoan cavy diets were greatly influenced by the amount of forage available, which varied according to the condition of the rangeland. Forbs were the main forage class consumed in all range conditions, but the species composition differed among condition classes. For example, several species of dicot forbs were consumed in areas of very good and good range condition, but Selaginella sellowii was the main dietary forb when the range condition was poor. We concluded that range condition affected the relative abundance and diet of Chacoan cavies of Western Chaco, Argentina. High Chacoan cavy density should be considered as an indicator of vegetation depletion caused by other factors rather than a primary cause of savanna degradation.