• 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.
    • 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.
    • Practical measures for reducing risk of alfalfa bloat in cattle

      Majak, W.; Hall, J. W.; McAllister, T. A. (Society for Range Management, 2001-07-01)
      Frothy bloat in cattle is a serious problem and is difficult to manage under field conditions as it progresses rapidly from early signs of distension to acute distress. Scientists at Agriculture and Agri-Food Canada centres in Western Canada are committed to the development of bloat-free alfalfa grazing systems, which may require feed additives or supplements. As well, a new cultivar of alfalfa (AC Grazeland), selected for a low initial rate of digestion, will soon be available. In grazing trials the cultivar reduced the incidence of bloat by an average of 56% compared with the control cultivar (Beaver). Commonly accepted mineral mixes for the prevention of bloat were tested and found ineffective but we have confirmed that poloxalene (Bloatguard®) is 100% effective if it is given intraruminally at the prescribed dose. However, under practical conditions, poloxalene can only be offered free choice and protection from bloat cannot be guaranteed. We have also shown that the water soluble polymer, Blocare® 4511, when used in the water supply is 100% effective in bloat prevention. This product is not yet registered in North America. Other strategies for bloat prevention will be discussed, including the selection of growth stages and grazing schedules, and the reduction of risk by wilting alfalfa or combining it with tannin-containing forages.
    • 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.
    • Statistical analyses of fluorometry data from chloroform filtrate of lamb feces

      Mukherjee, A.; Anderson, D. M.; Daniel, D. L.; Murray, L. W.; Tisone, G.; Fredrickson, E. L.; Estell, R. E.; Rayson, G. D.; Havstad, K. M. (Society for Range Management, 2001-07-01)
      Accurately identifying the botanical composition of free-ranging animal diets remains a challenge. Currently accepted procedures are time consuming, many requiring painstaking sample preparation while none produce data useful for real-time management. Automated procedures focusing on detection of chemical and/or physical plant properties using specific molecules called fluorophores offers possibilities for determining the species composition of herbivore diets. This study was designed to evaluate fluorometry techniques in herbivore diet determinations using fecal samples obtained from 13 lambs fed a basal diet of tobosa hay (Pleuraphis mutica Buckley), and containing 4 different levels (0, 10, 20, and 30%) of tarbush (Flourensia cernua D C.) leaf material. Chloroform (CHCl3) filtrate obtained from the lamb's feces was exposed to UV light from a xenon arc lamp. This caused fluorophore molecules in the filtrate to have their outer shell electrons move to a higher energy state as a result of UV light excitation. After excitation by UV light at 310, 320, 330, 340, 350, and 355 nm, the fluorophores returned to their ground state giving off light (fluorescence). This fluorescence intensity (counts) varied and when captured using appropriate electronics, produced 1,024 pairs of light intensities (counts) and fluorescent wavelengths between 175 and 818 nm in 0.63 nm increments. Previous research indicated differences among diets could be determined using distinct peaks in the red and blue regions of the visible light spectrum and a univariate (1 variable at a time) analysis. This research demonstrates the entire fluorescence data set can be used to determine differences among diets using multivariate statistics. Sequences of 5 increasingly complex statistical techniques were used to distinguish among diets: 2-dimensional plots, polynomial regression models, confidence interval plots, discriminant analysis, and 3-dimensional plots. Two-dimensional plots indicated 2 spectral fluorescence peaks, 1 in the blue-green (420-600 nm) and 1 in the red (640-720 nm) region of the visible spectrum. Because of the asymmetrical nature of these peaks, fifth-order polynomials were developed to differentiate among the 4 diets. Statistical reliability was high when discriminating between diets containing no tarbush leaf and the diets containing 30% tarbush leaf; however, it was not possible to statistically separate diets containing intermediate (10 and 20%) amounts of tarbush leaf material from each other or from the 2 extremes (0 and 30% tarbush leaf). These results suggest spectral signatures arising from fluorometry data may be useful for differentiating among botanical composition diets that differ in plant form, but that a multivariate approach may require large sample sizes.