[en] The potentialities of photographic transaxial tomographic methods are discussed. It is shown that unfiltered, transaxial tomographic summation images can yield high-quality tomograms of high-contrast objects. A direct and efficient photographic method for recording transaxial tomograms (grazing incidence tomography) is demonstrated, and various means for analog filtering are discussed. Grazing incidence tomography allows for high geometrical resolution for high- or medium-contrast objects. The present contrast performance is an order of magnitude different to that of computerised tomography, but an improvement of the method seems possible. (author)

[en] In this paper, results of a two year experiment conducted with cross-bred cattle grazing natural herbage under coconut with the objective of alleviating feed shortage and improving the quality by feeding tree fodder and a low cost concentrate with critical nutrients are discussed. The experiment was conducted in a coconut plantation at Kotawila, Matara district (WIZ) of the Southern Province of Sri Lanka. There were four treatments, coconut only with out fertilizer (T1); coconut only + fertilizer (recommended levels) (T2); coconut + tethered cross-bred heifers (165 kg ± 25) grazed natural herbage + urea treated straw during dry period (T3); coconut + tethered cross-bred heifers grazed natural herbage +tree fodder (2 kg/d fresh) + concentrate supplement (250 g/d) +urea treated straw during dry season (T4) arranged in a randomized block design with 3 replicates with a stocking rate of 2 heifers / 0.4 ha. The concentrate supplement contained Rice bran 400 g, Molasses 400 g, urea 100 g and minerals 80 g per kg with minimum amount of water to dissolve as a paste. Herbage dry matter yields in all treatments were positively related to the seasonal rainfall. The highest and lowest average bi-monthly dry matter (DM) yields were 2296 kg/ha/yr for T2 and 1496 kg/ha/yr for T3 respectively. The herbage yields of grazed treatments were marginally sufficient to meet the feed requirements of grazing cattle during the wet season. Botanical composition of herbage increased with grazing due to improved ground cover. In grazing treatments horizontal species such as Axonopus affinis, A. compressus and Puraria were dominant while vertical species such as Veronica cinera and Lantana camara were dominant in ungrazed plots. The differences in dry matter yield between T3 and T4 increased towards the latter stage of the experimental period, probably due to low grazing pressure by animals in T4 receiving supplementation. Similarly, herbage nitrogen content increased in T4 but decreased in T3 due to overgrazing by animals with out supplementation. Depletion of soil and herbage nitrogen in T3 stimulated conservation of nitrogen through recirculation within the animal. It was also estimated that each coconut palm received 141 kg of fresh dung /year in T3 and 146 kg/year in T4 along with 66.6 kg/urine /year in T3 and 69.6 kg/yr in T4. The dung and urine could totally replace nitrogen and phosphorous fertilizers applied to coconuts. Also it could reduce the potassium fertilizer applied to coconut by 85% in T3 and 88% in T4 and magnesium fertilizer applied by 85% in T3 and 88% by T4. There was a marked increase (P < 0.05) in live weight gains of cattle recording 688 g/d for heifers in T4 and 349 g/d for heifers in T3. Heifers fed supplements were in oestrus significantly earlier and at a higher body weight than those fed on natural herbage only. Thus fairly evenly matched initial ages and live weights of T3 (145.5 ± 2.4) and T4 (144.2 ± 2.9) groups, respectively differed significantly in favour of T4 at first oestrus. Heifer fed supplements calved significantly earlier than the heifers fed only natural herbage. An additional benefit of the integrated system was the improvement (P < 0.05) of coconut and copra yield per palm in grazed plots over monoculture plots, especially in T4 plots with animals receiving supplements. Soil nitrogen content also increased (P < 0.05) in grazed plots (T3 - 0.964% and T4 -1.004%) plots as compared to monoculture plots (T1-0.839%, T2-0.859%) demonstrating further benefits on cattle integration. Results suggest that supplementation of tree fodder and low cost concentrate to heifer's grazed natural herbage under coconut alleviated seasonal feed shortages and improved cattle and coconut performance, which contributed to sustainability of the integrated system. Further investigations, would show the actual benefits with the passage of time. (author)

[en] Over 90% of the population of zebu cattle in Nigeria belong to smallholder agro-pastoral farmers who adopt relatively inefficient production systems (Otchere and Nuru, 1988). Shortage of feed and poor quality of tropical pastures are a major constraint to livestock development, and this is often characterized by extended post-partum anoestrous periods. Biostimulation via pheromones can play an important role in mammalian behaviour and reproductive process. A total of 51 pleuriparous post-partum cows belonging to agro pastoralists were involved in a 2 x 2 factorial experiment for a period of 180 d. The cows were assigned randomly at calving to four treatments: (1) grazing only (no supplementation) and exposure to bull (NSBE); (2) grazing only (no supplementation) and no exposure to bull (NSNE); (3) grazing plus feed supplementation (each cow received 600 g of 20.8% crude protein of whole cottonseed supplement per day) and exposure to bull (FSBE); (4) grazing plus feed supplementation and no exposure to bull (FSNE). Post-partum cows were observed visually for the standard signs of oestrus (standing to be mounted) twice daily between 07:30 and 08:30h and 17:30 and 18:30h by experienced herdsmen and technicians. Cows in oestrus in the non-exposed group were taken to the bull for 24h for mating. Once weekly, whole milk samples were taken from cows 7-180 d post-partum for determination of progesterone concentrations using RIA kits. Cows with an increase in milk progesterone (P₄) concentration of <1 ng/mL from the weekly milk samples were used to analyse the number of days from calving to the time of resumption of ovarian activity. The interval from calving to resumption of post-partum ovarian activity for the feed supplemented (FS) cows was 107 d; earlier than the 136 d for the non-supplemented (NS) cows (P < 0.05; Table I). Similarly, cows exposed to bulls (BE) resumed post-partum ovarian activity earlier than the non-exposed (NE) cows with a difference of 16 d. Average daily gains for the FS cows were significantly higher than the NS cows. Resumption of ovarian activity for FSBE cows was 95 d, earlier than the 119 d for the FSNE cows (P < 0.05). The intervals to onset of postpartum ovarian activity were 24, 33 and 39 d significantly earlier in the FSBE cows than the FSNE, NSBE and NSNE cows (P < 0.05). The intervals to resumption of cyclic ovarian activity were 9 and 15 d earlier in the FSNE cows than the NSBE and NSNE cows (P< 0.05; Table I). At 120 d post-partum, the proportion of cows that had resumed ovarian activity was 75% for the FSBE cows, which was higher than the values of 42%, 23% and 33% for the NSBE, NSNE and FSNE cows, respectively (P < 0.05). In addition, by 120 d, the proportion of cows with ovarian cyclicity for NSBE cows was 42%; higher than the value of 23% for the NSNE cows (P < 0.05). By 150 d post-partum, 100% and 92% of the cows in the supplemented groups (FSBE and FSNE) had resumed cyclic ovarian activity compared with 75% and 69% for the unsupplemented cows (NSBE and NSNE; P < 0.05). This study indicates that supplementation and exposure to bulls can shorten the length of postpartum anoestrus. This agrees with previous studies which have reported that (Butler and Smith, 1989) and exposure of post-partum cows to bulls (Bolanos et al., 1997) hastened the onset of ovarian cyclicity after calving. The economic benefits of using exposure to bulls and supplementation to enhance early resumption of post-partum ovarian activity of cattle may serve as a management tool in livestock production. (author)

[en] Degraded environments are both widespread (being found on all continents on earth) and diverse. They have been broadly classified as: irrigated (and rain-fed) farmland with elevated water tables causing salinity; rain-fed farmland with soil erosion, loss of organic matter, nutrient depletion and weed invasion; and degraded rangeland. This review considers all these but with a focus on the first two, and particularly addresses options for simultaneous improvement in livestock production and landscape health. There is evidence that responsible grazing is consistent with ecosystem benefits and resilient land use systems; exclusion from grazing may reduce diversity and create management complexity. Responsible grazing however will only prevail if the land owner or user receives a financial benefit in the process. Solutions need to be profitable. In the development and management of grazing systems, expectations need to be realistic. The prescriptive approach to livestock feeding based on the selection and cultivation of a small range of improved plant species to meet predetermined energy, protein and mineral requirements is inappropriate. Degraded landscapes are often associated with a high edaphic and climatic variability that is best suited to a diverse range of plant species in an assembly that will fluctuate over time and space. This diversity means that under some circumstances degraded land may contribute to reduced risk within a whole farm business. Simultaneous objectives for livestock and landscape improvement may or may not contribute to the return of the landscape to its original state. In some cases stable vegetation that provides some of the functional benefits of the original landscape, such as improved biodiversity and soil health, combined with production benefits is the best option available. This provides an opportunity to establish a range of objectives in vegetation management and design. In Australia, such an approach is leading to the development of new farming systems that use salinised and degraded cropland for livestock. Livestock can cope with the diversity of vegetation that is suited to degraded landscapes; they have the ability to select a diet based on the minimisation of metabolic cost. They not only optimise energy and protein intake but select combinations that increase their ability to deal with toxins and parasites and to modify metabolic processes. This does not necessarily mean they will thrive; low biomass production cannot be overcome by increased choice alone, but it does mean we may need to learn from animal behaviour rather than endeavour to control it. With limiting biomass, complementary and supplementary feeds may still be required to improve the efficiency of use of grazed plants or to manipulate grazing where degradation is concentrated. There are also opportunities for strategic revegetation with plants selected for a range of nutritional, medicinal and ecosystem benefits. Just as plant species that have been bred for highly productive systems are usually inappropriate for degraded environments, so too are livestock. Traditional breeds may be better able to cope with the diverse feeding options, difficult terrain and variable climate and be more efficient in energy use. Animals bred for high production systems often partition a high proportion of available nutrients to production when feed supply is abundant but store less nutrients and are therefore less able to survive and reproduce during periods of low feed availability. Breeding within the relevant environment also exposes animals to stressors in utero and this may improve their ability to cope with these in later life. The concept of responsible management depends on available labour or technology for monitoring of both livestock and environment. Technology is now available or under development that will allow monitoring of livestock condition and detailed information on behaviours. These parameters are closely related to the condition of the grazing environment; the animal acts as a natural integrator of the information that describes the environment. This sensitive direct feedback mechanism is very powerful and offers new opportunities in the simultaneous management of livestock and the environment. In conclusion, degrading environments provide an opportunity for the profitable production of food. Livestock systems may be designed to retrieve or sustain landscape functionality. Livestock systems management within these environments requires an innovative approach that integrates the skills of animal physiology and behaviour, agronomy, plant ecophysiology, soil science and ecosystem ecology and management. This integration must operate outside the narrow perspectives that often characterise these disciplines. (author)

[en] The behaviour of simple predator-prey systems is well-known and was exploited to enable some general conclusions to be made about the stability of and productivity in extensive herbivore-plant grazing systems. The techniques employed were mainly graphical and, hence, lacked the mathematical bite for a full analytical discussion of the influencing parameters to be made. This paper attempts to remedy this deficiency. Then it turns to the more difficult problem when spatio-temporal variations are considered. The first part provides an opportunity to illustrate the occurrence of Hopf bifurcation and the appearance of oscillatory modes, the second part allows some interesting wave phenomena to be studied. 6 refs, 2 figs

[en] uss the application of grazing incidence x-ray techniques to characterize nanometer sized islands, which arise in strained layer heteroepitaxy of semiconductor systems ('quantum dots'). Using x-rays from synchrotron sources, grazing incidence small angle scattering (GISAXS) is demonstrated to yield structural information on shape, size and lateral correlation. Results on self-assembled Ge islands on Si(111) substrate are shown as an example. The crystalline properties of coherent quantum dots are obtained from grazing incidence diffraction (GID). From the analysis of reciprocal space maps the interdependence of shape and elastic strain within the quantum dots is determined. We discuss results on coherent InAs quantum structures on GaAs(100). (author)

[en] Highlights: • Effects of bitterling (A. macropterus) on macrophytes were studied in mesocosms. • Bitterling increased nutrient concentrations in the water column through excretion. • C. demersum and M. spicatum growth decreased and increased, respectively, with fish. • Bitterling dominance may disturbingly alter submerged macrophyte communities. Recovery of submerged macrophytes has been considered a key factor in the restoration of shallow eutrophic lakes. However, in some subtropical restored lakes, small omnivorous fish dominate the fish assemblages and feed in part on submerged macrophytes. Knowledge of the effects of small omnivores on the growth of submerged macrophytes is scarce and their responses are potentially species-specific, i.e. the growth of some species may be hampered by fish grazing while growth of others may be promoted by the nutrients becoming available by fish excretion. We conducted mesocosm experiments to examine the effects of the small omnivorous bitterling Acheilognathus macropterus, a common species in restored subtropical lakes in China, on nutrient concentrations and the growth of four species of submerged macrophytes (Hydrilla verticillata, Vallisneria denseserrulata, Ceratophyllum demersum and Myriophyllum spicatum). We found that the bitterling significantly increased nutrient concentrations via excretion and thereby enhanced the net growth of the less grazed nuisance macrophyte M. spicatum. In contrast, the net growth of C. demersum was reduced by the bitterling, most likely due to grazing as indicated by gut content analyses. Dominance by bitterling may, therefore, pose a threat to the long-term success of lake restoration by provoking a shift in the submerged macrophyte community towards nuisance species through selective grazing. Nutrient excretion may potentially also stimulate the growth of phytoplankton and periphyton, hampering the growth of submerged macrophyte.

[en] Grazing incidence x-ray diffraction is used to characterize the molecular arrangement of ultrathin Langmuir-Blodgett (LB) multilayers. Using two angles of incidence of the beam allowing its penetration either throughout the complete depth of the film or only through the external layers, we show that it is possible to discriminate between the molecular packing of the deeper monolayers and that of the external monolayers of the LB film

[en] While overgrazing is often blamed for environmental degradation, there is clear evidence that livestock are not inherently damaging to rangelands or farming landscapes, and, in fact, may be required for their sustained health and profitability. Moderate to heavy grazing has, in some cases created highly resilient and ecologically sound systems while under-grazing has resulted in dense woody growth and reduced species diversity. Conversion of rangelands into intensive crop/fodder production has also led to progressive loss of diversity, species connectivity and ability to recover. Well-managed livestock in either a grassland or mixed crop/livestock system offer a highly efficient method of increasing the production of high quality food with minimal environmental impact. Although an ecological case can be established for the continued use of livestock in degrading landscapes, the reality is, livestock will only be grazed responsibly if the owner receives a benefit from the process. Importantly, by providing a potentially profitable option, the revegetation of degraded or partly degraded landscapes may take place through the expenditure of private rather than public funding. Given the vastness of the landscapes in question and the urban priorities in the expenditure of public funds, significant progress is only likely if profitable solutions are available. This use of livestock may or may not contribute to the return of the landscape to its original state. In some cases stable vegetation that provides some of the functional benefits of the original landscape, combined with the productive benefits of a profitable livestock system may be the best option available. This then provides an opportunity to design a landscape based on a range of predetermined objectives which include both profit and ecosystem services. For example, in Western Australia, the revegetation of 10% of the 1 million ha of saline land with halophytic shrubs and salt tolerant forage has resulted in a system that provides valuable out of season feed for livestock, slows or reverses the elevation of saline groundwater tables and reduces salt and sediment run-off into waterways. Meeting the nutritional and environmental requirements of livestock grazing degraded environments will always be a challenge. Both over- and under-grazing are likely to result in a loss of species diversity. As livestock have the ability to select plants with higher digestibility, adequate nitrogen (crude protein) and low or manageable anti nutritional compounds, loss of diversity will be accompanied by a decline in nutritive value and palatability and reduced ability to deal with toxins. In the case of over-grazing the decrease in diversity and nutritive value will be accompanied with a decrease in feed availability. Management of livestock, vegetation and the interaction between the two is critical for productive grazing of such fragile environments. Where loss of diversity is a consequence of previous over-grazing, complementary feeding can improve feed intake, feed conversion efficiency and therefore productive potential. Examples include the provision of energy supplements to improve the utilisation of plants that contain high levels of non-protein nitrogen or to facilitate the breakdown of anti-nutritional compounds in the forage. Similar strategies can be applied to revegetation with selective planting to complement the composition and availability of other feed resources. Where revegetation is an option, there will be additional benefits in assessing the plant options for palatability, nutritive value, anti-nutritional properties, shelter and possible medicinal properties as well as selected ecosystem benefits. These do not need to be long-term and expensive plant breeding projects but may be well designed and localised screening programs based on indigenous plant species with known natural advantages. For reasons described above revegetation should complement rather than replace existing feed resources. Strategies to improve the intake and utilisation of forages in degraded environments have the potential to induce further degradation if not accompanied by improved grazing management. Technologies are now available that allow remote monitoring of livestock condition and behaviour. This type of direct information provides incentive and opportunity for livestock managers to tactically manipulate feeding and production. For example, monitoring change in both livestock and forage are grazing management options. While monitoring feed supply is the more traditional method advocated in high input grazing, more information and control may be available from direct livestock monitoring in the more extensive, low input systems that characterise degraded landscapes. Livestock will begin to lose weight long before feed supply is exhausted and live weight change may provide information on both available biomass and diversity of feed sources. Similarly, animal behaviours, such as time spent walking, grazing and feeding are related to feed supply and diversity. Grazing and feeding behaviour can be further assessed with the use of stable isotope techniques applied to feed and water intake. These techniques have the potential to optimise the combination of livestock production and ecological stability that will be required for the long-term productive use and revegetation of degraded landscapes. (author)

[en] The present study used Randomly Amplified Polymorphic DNA (RAPD) marker and scanning electron microscope (SEM) for achene surface to characterize and detect morphological and genetical molecular markers in 15 taxa of family Asteraceae collected from Al-Jouf and Al-Ula regions in the northern of Saudi Arabia and give attention to the importance of this family as grazing plants. The results of achene surface showed great differences between studied taxa and gave important criteria to characterize them. RAPD analysis scored molecular genetic markers that helped to characterize and detect variation between studied taxa. Primers produced a total of 105 bands of which 59 were species specific markers. The dendrogram generated by combination between RAPD polymorphism and achene scanning electron microscope features produced a clear view about the genetic relationship between studied taxa of Asteraceae. (author)