• An Evaluation of the Calibrated Weight-Estimate Method for Measuring Production in Annual Vegetation

      Tadmor, N. H.; Brieghet, A.; Noy-Meir, I.; Benjamin, R. W.; Eyal, E. (Society for Range Management, 1975-01-01)
      A double sampling technique, of visual weight estimates calibrated by harvesting, was applied to the measurement of biomass and production curves in grazed and ungrazed semiarid annual grassland. Good levels of accuracy can be achieved in such vegetation with a time expenditure significantly lower than by harvesting only. Some methodological problems were encountered and solved by modifications of the method. In some conditions the method can be used for estimating animal intake.
    • Bio-economic evaluation of stocking rate and supplementary feeding of a beef herd

      Seligman, N. G.; Noy-Meir, I.; Gutman, M. (Society for Range Management, 1989-07-01)
      The effect of varying price ratios between liveweight and supplementary feed on the optimum stocking rate (SR) of a beef herd on range is analyzed in relation to the net value of weaned calf live weight. While the basis for determining optimum stocking rate is generally the value of production and costs per unit area, the animal performance per se is often a major management criterion, especially where the capital investment in livestock is high and where risk avoidance is an important consideration. Consequently, equations expressing the net value of beef production per unit of land and per animal unit are formulated as a function of SR. Parameter values for the equations were taken from a grazing trial conducted in the Galilee in Israel where a beef herd was maintained yearlong on native range 5 years at 3 different SR's, 0.50, 0.67, and 0.83 cows/ha. The animals were supplemented ad libitum with poultry litter during the dry summer months. During the transitional period between the opening rains and range readiness, poultry litter was enriched with 20% barley grain. In addition, straw was given at an average rate of 80 to 375 kg/ha in the intermediate and highest stocking rates. Over the range of SR's studied, it was shown that when supplementary feed and other per animal costs are high, net value of production per unit area of range declines with SR even though total production increases. On the other hand, when fixed range and management costs are high, the net economic benefit per cow increases with SR even though production per cow decreases. It is concluded that the optimum SR for a given situation depends not only on the input/out price ratios but also on the criterion for evaluating economic value that is most revelant to the manager.
    • Heavy stocking and early-season deferment of grazing on Mediterranean-type grassland

      Gutman, M.; Holzer, Z.; Baram, H.; Noy-Meir, I.; Seligman, N. G. (Society for Range Management, 1999-11-01)
      An experiment with beef cows grazing Mediterranean-type grassland was conducted to study the effect of grazing deferment at the beginning of the growing season on pasture productivity and animal performance under intensive herd management conditions. The grazing trial was composed of 4 treatments (deferred grazing at stocking rates of 0.83 and 0.67 cows per ha and continuous grazing at 0.67 and 0.5 cows per ha) replicated in 2 blocks and continued for 5 consecutive years. The herds were given low-energy supplemental feed during deferment and during the dry summer. At the intermediate stocking rate, at which both deferred and continuous grazing were compared, herbage production was significantly reduced by grazing during the 'deferment period' and calf weaning weights without deferment were significantly lower than in the deferred grazing treatments. Weaned live weight per cow was significantly lowest in the continuous intermediate treatment. Weaned weight per hectare was greatest at the highest stocking rate (with deferment). Utilization of supplementary feed per unit weaned live weight was significantly greater in the deferred treatments. Only about a third of the herbage production was grazed, even at the heavy stocking rates. Herbage production varied more between years than between treatments. It is concluded that in the system studied, deferment with supplementary feeding becomes important for both animal and vegetation production as stocking rate approaches and exceeds 0.67 cows ha-1. With deferment, herbage production during the main growing season can be maintained even under heavy grazing pressure. This result can be explained with a simple dynamic growth and grazing model.
    • Herbage production of Mediterranean grassland under seasonal and yearlong grazing systems

      Gutman, M.; Seligman, N. G.; Noy-Meir, I. (Society for Range Management, 1990-01-01)
      Data from 2 consecutive grazing experiments conducted over 7 years on a Mediterranean type grassland were used to calculate forage consumption by herds of beef cattle maintained at different stocking rates and in different grazing systems. In the first experiment the animals were on the experimental range for 8 months of the year; in the second, grazing was yearlong. Total production of herbage mass was estimated from these data and from the residual litter in the paddocks at the end of the dry season. Production of dry herbage mass varied between 2,600 and 3,800 kg/ha, with a mean and SD of 3,060 +/- 300 kg/ha. While variation between years was relatively small but significant (P<.01), the effect of stocking rate or grazing system (seasonal, yearlong) was smaller and not significant. It is concluded that the attained level of herbage production of Mediterranean grassland on relatively shallow basaltic protogrumosols is not sensitive to total precipitation over a very wide range or to grazing system. It may be dependent on the availability of nutrients, especially nitrogen, and the seasonal distribution pattern of available soil moisture in a restricted rooting zone.
    • Opportunistic management for rangelands not at equilibrium

      Westoby, M.; Walker, B.; Noy-Meir, I. (Society for Range Management, 1989-07-01)
      We discuss what concepts or models should be used to organize research and management on rangelands. The traditional range succession model is associated with the management objective of achieving an equilibrium condition under an equilibrium grazing policy. In contrast, the state-and-transition model would describe rangelands by means of catalogues of alternative states and catalogues of possible transitions between states. Transitions often require a combination of climatic circumstances and management action (e.g., fire, grazing, or removal of grazing) to bring them about. The catalogue of transitions would describe these combinations as fully as possible. Circumstances which allow favorable transitions represent opportunities. Circumstances which threaten unfavorable transitions represent hazards. Under the state-and-transition model, range management would not see itself as establishing a permanent equilibrium. Rather, it would see itself as engaged in a continuing game, the object of which is to seize opportunities and to evade hazards, so far as possible. The emphasis would be on timing and flexibility rather than on establishing a fixed policy. Research under the state-and-transition model would aim to improve the catalogues. Frequencies of relevant climatic circumstances would be estimated. Hypotheses about transitions would be tested experimentally. Often such experiments would need to be planned so that they could be implemented at short notice, at an unknown future time when the relevant circumstances arise.
    • Rehabilitation of Mediterranean dwarf-shrub range-land with herbicides, fertilizers, and fire

      Henkin, Z.; Noy-Meir, I.; Kafkafi, U.; Gutman, M. (Society for Range Management, 1998-03-01)
      An experiment was conducted on a Mediterranean hill range dominated by communities of spiny dwarf-shrubs (mainly prickly burnet Sarcopoterium spinosum (L.) Spach) in order to determine the effects of P fertilizer application, shrub control and fire on the herbaceous and shrub components of the community. Herbicide (2,4-D) application eliminated almost all the shrubs in the first year and their regeneration was relatively slow: 6 years after the application, shrub cover was less than one-third of what it was at the beginning of the experiment. After fire, regeneration was rapid and original shrub cover was restored within 6 years. A single application of phosphorus fertilizer (4.5-9.0 g P m-2) significantly retarded regeneration of shrub cover and produced a three to five fold increase in herbaceous biomass production. The residual effect of the fertilizer application was still significant at the end of the 7-year monitoring period. The herbaceous vegetation in the P-fertilizer treatments was dominated by annual legume species throughout the experiment. The prolonged response of the herbaceous sward patches to a single P application appeared to be caused by the gradual release of phosphate from the applied fertilizer and also by the summer grazing system that facilitated recycling of soil nutrients on the site. Above-ground biomass on herbaceous sward patches increased not only as a consequence of nutrient amelioration, but also because of reduced competition from the lower shrub cover following fire or herbicide application. Shrub recovery that was dependent on the residual cover in the first year following fire and/or herbicide treatment, was further retarded by competition from the vigorous herbaceous vegetation that benefited from nutrient amelioration. The implications of these results for range improvement depend to a large degree on the economic conditions relevant to the grazing system.
    • Stocking density and production of a supplemented beef herd grazing yearlong on Mediterranean grassland

      Gutman, M.; Holzer, Z.; Seligman, N. G.; Noy-Meir, I. (Society for Range Management, 1990-11-01)
      The possibility of attenuating the negative effects of high stocking rate (SR) on animal production by using inexpensive low energy supplements (mainly poultry litter) was examined in a herd of small, crossbred cows graxing year;ong on Mediterranean grassland. Herds of 15 to 25 cows were stocked at 0.50, 0.67, and 0.83 cows/ha in replicated blocks. Weaning weights and ADG of calves were higher (P<.001) at the low SR, but there were no differences between the moderate and heavy stocking treatments. Weaned weight per hectare as well as supplementary feed consumption were highest at the high SR, but differences between the low and moderate stocking treatments were not significant. Conception rates fluctuated between years and declined at the heavy SR, only to recover dramatically in the inst year of the experiment. Weaning rates were variable both within and between SR’s from year to year, but overall 5-year SR means were not significantly different. It is concluded that on the seasonal Mediterranean grassland typical of eastern Galilee where quality of dry summer pasture is low, supplementation based mainly on poultry litter and straw can buffer some of the effects of high stocking rates on animal production but cannot ensure consistently high productive performance even at low SR.