• Anti-quality factors associated with alkaloids in eastern temperate pasture

      Thompson, F. N.; Stuedemann, J. A.; Hill, N. S. (Society for Range Management, 2001-07-01)
      The greatest anti-quality associated with eastern temperature pasture grasses is the result of ergot alkaloids found in endophyte-infected (Neotyphodium ceonophialum) tall fescue (Festuca arundinacea Schreb.) The relationship between the grass and the endophyte is mutualistic with greater persistence and herbage mass as a result of the endophyte. Ergot alkaloids reduce growth rate, lactation, and reproduction in livestock. Significant effects are the result of elevated body temperature and reduced peripheral blood flow such that necrosis may result. Perturbations also occur in a variety of body systems. Planting new pastures with seed containing a "non-toxic" endophyte appears to be a potential solution. Ergotism results from the ingestion of the scelerotia of Claviceps purpurea containing ergot alkaloids found on seed heads. Ergotism resembles the effects of endophyte-infected tall fescue. Endophyte-infected perennial ryegrass (Lolium perenne L.) contains ergot and lotirem alkaloids that result in reduced growth and tremors. Reed canarygrass (Phalaris Anundinacba L.) contains tryptamine, hordenine and gramine alkaloids that reduce growth. Annual ryegrass (Lolium multiplorum L. may contain galls with cornetoxins which result in neurological signs.
    • Cattle use of foothills rangeland near dehydrated molasses supplement

      Bailey, D. W.; Welling, G. R.; Miller, E. T. (Society for Range Management, 2001-07-01)
      Strategic supplement placement has been shown to be an effective tool to lure cattle to underutilized rangeland. The goal of this study was to determine where cattle grazed when supplement was placed in foothills rangeland. The study was conducted in 4 pastures in northern Montana that were dominated by cool-season grasses. For 2-week periods beginning in October 1998 and ending in January 1999, dehydrated molasses blocks (30% CP) were placed in locations within 3 pastures that were steeper and further from water. Forage utilization was measured at the time of supplement placement and again at removal. Increases in forage utilization during each period (14%) were similar (P > 0.1) at distances of 30 to 600 m from supplement, and increases were additive across periods. Forage utilization was evaluated in a fourth pasture during August and September 1999 at distances of 50 to 3,000 m from the supplement. Forage use declined (P < 0.01) at further distances from supplement, and forage use at distances less than 600 to 800 m from supplement was greater than the average of all measurements collected throughout the pasture. During the autumn and early winter at the 2 pastures located near Havre, Mont., 53% of the cows were observed within 600 m of supplement and 47% were observed at greater distances from supplement. Eighty-one of the 159 cows grazing the 2 pastures near Havre (245 and 330 ha) were fitted with Global Positioning System (GPS) tracking collars. The collared cows spent 37% of their time within 600 m of supplement. Uniformity of cattle grazing can be enhanced by the placement of dehydrated molasses supplement in rugged topography, and the area influenced can include distances up to 600 m from supplement.
    • Complementary grazing of native pasture and Old World bluestem

      Gillen, R. L.; Berg, W. A. (Society for Range Management, 2001-07-01)
      Native pasture and Old World bluestems (Bothriochloa spp.) have contrasting herbage production characteristics that suggest potential for incorporation into a complementary forage system. We compared 2 yearling beef production systems consisting of either native pasture (Native) or Old World bluestem combined with native pasture (Old World bluestem-Native) over 5 years. Crossbred steers (initial weight 257 kg) grazed only native pasture in the Native system, but alternated between Old World bluestem and native pastures in the Old World bluestem-Native system. Production system had no effect on the frequency of any plant species in the native pastures (P > 0.16) even though stocking rate in the growing season was increased 31% in the Old World bluestem-Native system. Peak standing crop of Old World bluestem averaged 4640 kg ha(-1) but did not differ between the cultivars 'WW-Iron Master' and 'WW-Spar' (P = 0.16). Individual steer gain was higher in the Native system during the Winter (P < 0.01) and Early Native (P = 0.03) management periods, but was greater in the Old World bluestem-Native system when steers were grazing Old World bluestem in June and July (P < 0.001). Over the entire season, steers in the Native system gained 13.5 kg head(-1) more than steers in the Old World bluestem-Native system. Total livestock production was greater in the Old World bluestem-Native system (77 versus 47 kg ha(-1), P < 0.01). Relative economic returns between the 2 systems were dependent on the marginal value of livestock gain and the relative costs of production for the 2 types of pasture. With average costs for native pasture of 17 ha(-1) and for Old World bluestem pasture of 62.10 ha(-1), the Native system was often more profitable, even though livestock production per ha was much higher with the Old World bluestem-Native system. Lower costs for native pasture and high values of livestock gain favored the Native system.
    • Dietary structural types of polygastric herbivores at different environments and seasons

      Pelliza, A.; Willems, P.; Manacorda, M. (Society for Range Management, 2001-07-01)
      A classification of dietary structural types that represents different arrangements of forage classes is proposed. It may be especially useful for interpreting and comparing herbivore diets from different environments. As an example, a data set with the botanical composition of 55 pooled fecal samples determined by microhistological analysis was analyzed. These samples came from 4 species of range herbivores (cattle, sheep, goat, and guanaco -Lama guanicoe-), from 9 different environments of Northern Patagonia (Argentina) during 3 seasons. Based on plant characteristics related with the capacity of the animals to eat and digest each plant and with the occasional or permanent presence of them in the vegetation, the information was grouped into 5 forage classes: woody plants, perennial grasses, annual grasses, grasslikes, and forbs. A principal component analysis of the grouped data was conducted. The graphic representations evidenced the gradual changes in the structure of the data. Later, working over the subspace defined by the 3 first principal component axes, a hierarchical classification was performed that resulted in 9 dietary structural types. These types represented variation that resulted from the interaction of pasture differences, species of herbivore and season. This concept is an abstraction developed from the experience, to extend its utility beyond the particular cases.
    • Low density of prickly acacia under sheep grazing in Queensland

      Tiver, F.; Nicholas, M.; Kriticos, D.; Brown, J. R. (Society for Range Management, 2001-07-01)
      Populations of an introduced woody weed, prickly acacia (Acacia nilotica (L.) Delile ssp. indica (Benth.) Brenan syn. Acacia arabica (Lam.) Willd. ssp. indica Benth.), were surveyed at 4 sites in central Queensland. There is a significantly lower frequency of plants of 3 m in height within populations which have been grazed by sheep, indicating that browsing by sheep reduces regeneration. There were higher losses of seedlings at a sheep-grazed site than at cattle-grazed sites. These results support previous assertions that prickly acacia is regenerating more successfully on cattle properties, because cattle both disperse seeds and are less effective herbivores. In regions of low annual rainfall, prickly acacia is capable of forming dense stands (up to 2,700 shrubs ha(-1)) in lowland landscape types. Stands are less dense in upland landscapes (maximum of 718 shrubs ha(-1)). Of most concern is that in regions of high annual rainfall prickly acacia can form extremely dense thickets across most landscape types (up to 3,400 shrubs ha(-1)). We suggest that prickly acacia is most likely to become a management problem on cattle properties, and an extreme problem in high annual rainfall areas. The inclusion of sheep in livestock rotations may be an effective control measure in the Mitchell Grasslands, but this may not always be possible. A high priority is to prevent prickly acacia from expanding its range into equivalent high rainfall areas within Queensland, and also in the Northern Territory, northern New South Wales, and Western Australia. This could be achieved by quarantining livestock which have come from infested properties until seeds have passed through the digestive tract, after about 6 days. Management strategies at the property level should aim to prevent further spread of prickly acacia by controlling cattle movements between paddocks during periods when cattle are ingesting pods and seeds.
    • Review of toxic glycosides in rangeland and pasture forages

      Majak, W. (Society for Range Management, 2001-07-01)
      Ruminants are a diverse group of mammals, both domestic and wild species, that exhibit microbial fermentation prior to gastrointestinal activity. During the digestive process, glycosides and other natural products are exposed to ruminal microorganisms and metabolised as substrates. Most compounds are converted into nutrients but some become toxic metabolites. At least 10 types of toxic glycosides occur in forage species. Glycosides are characterized by the presence of one or more sugars linked to the alcohol or thiol functions of the non-sugar portion of the molecule, which is called the aglycone. The biological activity of the glycoside is usually determined by the chemical nature of the aglycone. The aglycones are released by microbial enzymes and may undergo further enzymatic or non-enzymatic transformations to yield toxic metabolites that can be absorbed from the gastrointestinal tract. Microbial detoxification of the aglycone is also possible. Further biotransformation of the aglycone can occur in the liver. A review is presented on glycosides that are toxic to ruminants. The discussion covers aliphatic nitrocompounds, cyanogenic glycosides, cardiac glycosides, saponins, glucosinolates, diterpenoid glycosides, bracken glycosides, calcinogens, phenolic glycosides and ranunculin. Clinical signs of poisoning and treatment of livestock as well as management strategies for the prevention of poisoning are considered.
    • Structural anti-quality characteristics of range and pasture plants

      Laca, E. A.; Shipley, L. A.; Reid, E. D. (Society for Range Management, 2001-07-01)
      Structural anti-quality characteristics are physical plant traits that reduce the performance and productivity of herbivores and quality of their agricultural products. Most structural anti-quality characteristics of plants affect the rate at which herbivores gather and ingest forages, reducing the total amount of food obtained or increasing the time necessary to obtain food. Structural anti-quality can substantially influence searching time (e.g., plant crypticity, distribution), cropping time (e.g., plant fibrousness, tensile and shear strength), and bite size (e.g., plant canopy structure, spinescence). Plant structural characteristics can also reduce digestion (e.g., silica), cause injury (e.g., spines, awns, burrs, calluses), or reduce the quality of animal products, such as wool (e.g., propagules). The effects of structural antiquality characteristics depend on the morphology of the herbivore, especially its size, the morphology of the focal plant, and their context within the habitat. Integrated grazing management plans should consider options to reduce the negative effects of structural anti-quality. Carefully selecting appropriate livestock species with previous experience, and the appropriate season of grazing can minimize anti-quality on rangelands. Because structural anti-quality may actually promote sustainability of grazing systems by preventing severe defoliation, or by providing refuges for highly desirable forages, it may not be desirable to completely counteract their effects.