Now showing items 21-29 of 29

    • Efficiency of Forage Harvest by Grazing Cattle

      Allison, C. D.; Kothmann, M. M.; Rittenhouse, L. R. (Society for Range Management, 1982-05-01)
      Three grazing trials of 14 days each were conducted in April, July, and September, 1977, to examine the effects of grazing pressure on forage disappearance, organic matter intake, and the relationship between intake and forage disappearance. Levels of grazing pressure studied were 10, 20, 40, and 50 kg of forage allowed per animal-unit per day (kg/au/da). Standing crop was measured before, during the middle, and immediately after each trial. Organic matter intake was estimated at the beginning and end of each trial by the fecal excretion:indigestibility ratio technique. Total standing crop declined steadily during the grazing trials, with forage availability being significantly less at the end than at the beginning or middle of the trials. Averaged over the three trials, total forage disappearance during a 14-da grazing period was 236, 334, 355, and 457 kg per pasture and forage losses per au per day were 8.5, 12.0, 12.7, and 16.3 kg for the 10, 20, 40, and 50 kg/au/da grazing pressures, respectively. However, daily intake averaged across all treatments, periods, and trials was approximately 9 kg/au/da. At the grazing pressure level of 10 kg/au/da, forage disappearance approximated the average daily intake, whereas, grazing pressures of 20, 40, and 50 kg/au/da had forage disappearances that exceeded intake by 28, 48, and 90%, respectively. These data indicate a possibility for a two-fold increase in the efficiency of forage harvest by grazing cattle as grazing pressure is increased.
    • Effect of Continuous Grazing on the Diet of Steers

      Yates, D. A.; Clanton, D. C.; Nichols, J. T. (Society for Range Management, 1982-05-01)
      Continuous grazing of Sandhill native forage at a normal stocking rate in late August had no effect on organic matter intake (OMI), but the protein content and in vitro organic matter digestibility (IVOMD) declined over a 3-week period. The average OMI was 75 g/kg W^.75. As the availability of forage declined, the ability of the steers to selectively graze was apparently reduced. Similarly, continuous grazing of mixed prairie-type range from October 30 to March 13 had no effect on OMI but the protein content of the diet was reduced. The IVOMD did not change during the winter grazing trial. The average OMI was 66 g/kg W^.75 Steer calves gained .24 kg daily during the grazing period.
    • Contribution to the Ecology of Dactyloctenium aegyptium (L.) P. Beauv.

      Sharma, B. M.; Chivinge, A. O. (Society for Range Management, 1982-05-01)
      Dactyloctenium aegyptium, which is a nutritious fodder, grows abundantly in the campus of University of Ibadan, Nigeria, under tropical climate and supported by reddish-brown loamy soil. The species shows morphological variations and three forms have been recognized. Form A is small sized, Form B medium, while Form C is large. Each form grows with different associated species, though some of them are common to all forms. The three forms behaved differently with respect to germination requirements, biotic disturbance, and water stress. Cultural experiments revealed germination lower on filter paper than on soil, a progressive decrease in germination with depth, no germination at 4 cm and 5 cm depths, and a general increase in germination from 10 degrees C to 25 degrees C. Form C did not germinate at all in total darkness but had the highest germination in glass-house and it was the only one that germinated in continuous light. Most of the results of various germination experiments showed that Form A had the least germination, followed by Form B, while Form C had the highest germination. Experiments on water stress revealed that Form B showed the best growth but it was only Form C that had flowered. There are persistent differences in three Forms with regard to growth habit, period of maturity, spike coloration, and germination behavior, which indicate that they are likely to be ecotypes.
    • Cattle Grazing and Behavior on a Forested Range

      Roath, L. R.; Krueger, W. C. (Society for Range Management, 1982-05-01)
      Environmental and topographic parameters on a mountainous forested range were analyzed to establish causes of cattle behavioral responses. Distinct home range groups of cattle were identified through examination of quality and patterns of forage use, cattle distribution, herd social structure, and cattle activities. The home range of one group encompassed only upland areas. Water and vegetation type were important parameters in determining area and degree of use. Vertical distance above water was the most important factor in determining vegetation utilization on moderately steep slopes. Time after sunrise and relative humidity factors were key factors in determining kind and timing of cattle activity.
    • Botanical Composition of Summer Cattle Diets on the Wyoming High Plains

      Samuel, M. J.; Howard, G. S. (Society for Range Management, 1982-05-01)
      Botanical composition of the summer diet was determined for cattle grazing semiarid grassland in southeastern Wyoming. Diet samples from beef cattle with esophageal fistulas were examined using a microscope technique. Western wheatgrass was the most abundant single species. Western wheatgrass, blue grama, sedges, and needleandthread made up 70% of the diet. Western wheatgrass and needleandthread were found in the diet at proportions greater than the relative amount available; conversely, blue grama was found at proportions less than the relative amount available.
    • Botanical Composition of Steer Diets on Mesquite and Mesquite-Free Desert Grassland

      Galt, H. D.; Theurer, B.; Martin, S. C. (Society for Range Management, 1982-05-01)
      Botanical composition of cattle diets on mesquite and mesquite-free desert rangeland was determined on a weight basis by a microscope point technique and density constants of species. Pastures consisted primarily of grasses, small amounts of forbs and shrubs, and velvet mesquite (17% crown canopy) on one unit. Dietary composition of plant groups consisted of 67 to 97% grasses, 0 to 4% forbs, and trace to 33% shrubs. Species composition of diets varied by seasons and among animals. Plant preference was not necessarily related to plant availability. Composition of diets was markedly different from composition of pastures. Black grama averaged only 3% of diets, but comprised about one-third of herbage production. Arizona cottontop, which averaged 20% of herbage on pastures, was the most consistently selected species, averaging 34% of the diet. Seasonal preference was shown for certain grasses such as rothrock grama in spring and bush muhly in winter. Highest preference for shrub species was shown in winter and early summer. Overall dietary composition between pastures was much the same, but average herbage production for a 2-year period was 347 kg/ha greater where mesquite had been controlled. Leaves comprised the major plant part of steer diets on both pastures. Leaf content of diets increased from winter to summer while stems decreased for the same periods. Botanical composition of animal diets can be a guide to more efficient use of the range resource by grazing animals.
    • Botanical Composition of Determination of Range Herbivore Diets: A Review

      Holechek, J. L.; Vavra, M.; Pieper, R. D. (Society for Range Management, 1982-05-01)
      Procedures used for estimating the botanical composition of the range herbivore's diet include diet observation, utilization techniques, fistula sampling, and fecal analysis. Each of these procedures has important limitations. Direct observation requires minimal time and equipment inputs but accuracy and precision are a problem, particularly with wild animals. Utilization studies are generally unsuitable when plants are actively growing and more than one herbivore is using the area under study. Fistula methods are accurate but are difficult to use with wild animals. In addition they are costly and require considerable time. The esophageal fistula is preferable to the rumen fistula because it provides more accurate information and requires less labor. Stomach analysis involves animal sacrifice and, therefore, is generally restricted to wild animals with large populations. However, trocar sampling of the rumen contents is a new method that avoids this problem. Fecal analysis has been used extensively in recent years to evaluate diet botanical composition of wild herbivores. This procedure gives good precision but accuracy is a problem because of differential digestion between plant species. Techniques are available that can be used to reduce this source of error. Microhistological analysis has become the most widely used method for quantifying botanical composition of masticated forage or fecal material. Recent studies show microhistological analysis can give an accurate representation of percent diet botanical composition by weight if observers use had compounded diets to check their accuracy. A new procedure, infrared spectrophotometry, may have considerable potential for evaluating herbivore diet botanical composition of fistula or fecal samples.
    • An Evaluation of 17 Grasses and 2 Legumes for Revegetation of Soil and Spoil on a Coal Strip Mine

      Nichols, P. J.; McGinnies, W. J. (Society for Range Management, 1982-05-01)
      Seventeen grass species and two legumes were evaluated in a greenhouse study to determine their potential for revegetation of coal strip mine areas. Each species was grown in 25 cm of topsoil placed over 28 cm of mine-spoil or in 53 cm of spoil without topsoil. Herbage yields were seven times greater and root yields six times greater when the grasses were grown in topsoil than when grown in spoil without topsoil. When herbage production, root production, and crude protein were considered together and given equal weight, the five species with the highest combined ratings when grown in 25 cm of topsoil over spoil were tall fescue, hard fescue, Russian wildrye, western wheatgrass, and Arizona fescue. All grass species studied produced relatively low yields when grown in spoil without topsoil. Average herbage yields for the native and introduced grass species studied were similar, but introduced species averaged greater root production, particularly in spoil material. Two legumes, alfalfa and cicer milkvetch, produced much higher yields and higher crude protein than any of the grasses studied whether grown in topsoil over spoil or in spoil without topsoil.
    • An Analysis of Forage Preference Indices

      Loehle, C.; Rittenhouse, L. R. (Society for Range Management, 1982-05-01)
      Of those models currently used to describe the preference of animals for various plants under given conditions, all have serious shortcomings for purposes of accurately explaining the data, in the regression sense. When five equations, based in various ways on preference and availability, were used to estimate diets of cattle and sheep, no clear advantage of one expression over another could be found. All models tested with the sheep data resulted in increased predicted sums of squares compared with total sums of squares. In contrast, models tested with the cattle data showed some reduction in unexplained variation in diet estimates during the entire year, spring, and summer, but not during fall. This improvement was probably because the cattle pastures were more homogeneous than the sheep pastures and species were aggregated. The best model was Ratio 4 (preference-availability) but it requires a complex and expensive parameter estimation technique. It was concluded that sampling problems combine with inadequacies of the preference indexes to prevent accurate representation of the concept of diet preference. It was also concluded that sampling problems arise when the fecal, rumen fistula, or esophageal fistual techniques are used to estimate diets. A technique for adjusting these techniques to make them suitable for predicting diets was described. Further investigations into animal behavior are needed to determine variables which affect what the animal perceives as being desirable in relation to what is available.