Integration of geospatial and cattle nutrition information to estimate paddock grazing capacity in Northern US prairie

Spatiotemporal variability in forage quantity and quality requires that regular assessment is needed of the capacity for grasslands to support livestock nutritional requirements. Current methods for estimating grazing capacity are typically production-based and lack the forage quality data necessary to match nutrients in forage with livestock requirements in real time. This paper describes a method for estimating short-term grazing capacity for small (1–20 ha) paddocks using cattle nutrition and high spatial resolution forage data in Geographic Information Systems (GIS) for mixed-grass prairie. We define grazing capacity as the number of days a specific paddock will support the nutritional requirements of beef cattle. We integrate previously published methods for estimating cattle nutritional requirements, forage quality (crude protein) and forage quantity (phytomass) to estimate grazing capacity based on current standing-crop. The model utilizes high-resolution (<30-m) satellite imagery or field data to estimate short-term grazing capacity for small paddocks. Three versions of the model were evaluated on one paddock under cattle use in 2007. One version was parameterized using data collected on June 22 from the Landsat Thematic Mapper (TM), one version was parameterized using data collected June 23 from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and one version was parameterized using data collected June 20 from field clippings. TM and ASTER versions underestimated grazing capacity by four days while the field version overestimated grazing capacity by one day. Results suggest integration of cattle nutrition and forage data in GIS could assist with stocking rate adjustments, but additional trials are needed.     

A simulation model for managing perennial grass pastures. Part II—a simulated systems analysis of grazing management

A model for managing perennial grass pastures was used to simulate a grazing experiment on common bermudagrass pastures at Booneville, Arkansas. The experiment used sixteen years' weather data from this location.The management variables included number of fields, rotation period, and simulated grazing rate. The grazing season was from 1 June to 22 September each year, and simulated performance data were obtained for successive six-day periods throughout the grazing season. The attributes of performance data included: daily harvest rate, digestible dry matter and cell content nitrogen harvested, potential tissue production, reserve carbohydrates at the end of the year and the ratio of forage on offer to the simulated grazing rate.Analyses of these simulated performance data provided an inference base to support a recommendation concerning the management variables. The recommendation is as follows: a four-field system, a nine-day rotation period and 84 kg/ha/day simulated grazing rate. The results along with other simulated grazing scenarios will be used to plan field experiments at Booneville, Arkansas.     

Ruminant feeding systems in West Java,Indonesia

Data collected from 350 ruminant rearers are presented in relation to four altitude strate in West Java. In each stratum and sample village, further selection of rearers was made on the basis of main land-use type and livestock species reared. The study was conducted in the dry season of 1982.Sixteen existing systems of feeding ruminants were identified. These comprised different combinations of hand feeding, full grazing, tethering and free range grazing practices. Further simplification resulted in four main systems—full grazing, full hand feeding, mainly grazing and mainly hand feeding.Characteristics and prevalence of these feeding systems are described and related to altitudinal strata and seasons.Hand feeding was the most common system above 100 m in altitude and was especially prevalent in the wet season. However, below 100 m (where 50% of livestock units are located) combinations (mainly grazing) were most common in the wet season and grazing was predominant in the dry season.This study is intended to provide a sound background for planning research on feeding, and for village livestock development in West Java.     

A risk efficiency analysis of backgrounding and finishing steers on pasture in Saskatchewan, Canada

This paper combines an agricultural production decision support tool, GrassGro, with economic risk efficiency theory to examine several cattle feeding options that include various grazing systems for three climatic environments in Saskatchewan, Canada. Historical weather data were used to simulate a distribution of forage and cattle production data for each of several grazing systems during a 21-year period, 1978–1998. Price variability was included by varying year 2000 prices using historical price margin changes between the buying and selling weights of cattle. The risk efficiency analysis was completed using the Mean Standard Deviation (MSD) framework, and stochastic dominance principles.

Results of the study suggested that feeding systems, which included grazing, were economically competitive with traditional feedlot feeding systems and grain farming. Finishing cattle on pasture with the addition of a barley supplement was an attractive option, especially when high pasture productivity can be achieved. In all locations, more intense systems that included pasture fertilization and provision of an energy supplement, improved production and risk efficiency. Although the average net returns of all these feeding simulations were negative, the returns of traditional grain crops were even more negative. It is these negative returns in grain operations that lead to the incentive for producers to diversify into cattle production. Despite the negative net returns, the cash flow (range −$15.59 to $407.54 ha⁻¹) was mostly positive in all three locations.     

Simulation of beef cattle production systems in the Llanos of Colombia: Part 2—Results of the modelling

Verifications and validations were conducted of a simulation model of beef cattle production on tropical ranges of the Colombian Llanos. Liveweight changes were simulated for individual cows sampled at random, for cow herds alternately grazing native savanna and molasses grass (Melinis minutiflora) and for steers grazing native savanna. Correlation coefficients between observed and simulated liveweight change were high. Simulations of the calving rates of cow herds from two experiments at Carimagua Research Station were also conducted and there was reasonably good agreement between observed and simulated data. Shortcomings of the model included an inability to simulate the heavy weight losses of grazing animals on molasses grass during the dry season and under-estimates of calving rates for the most productive herds. An experiment was conducted with the validated model from which it was concluded that grazing molasses grass and weaning of calves at 84 days of age would do little to increase calving rate.     

Kleingrass growth and utilization by growing steers

A model of kleingrass (Panicum coloratum L.) growth and utilization by steers is presented. The model included stochastic inputs of climatological characteristics, water retention at different soil depths, rainfall runoff, potential evapotranspiration, forage growth, forage intake and steer performance. The model was used in a 2 × 3 × 4 factorial experiment where the factors were energy systems (ARC, 1965 versus NRC, 1976), stocking rates (2·47 head per hectare, 4·32 head per hectare and 6·18 head per hectare), and four management options. Individual steer weights by months were not significantly affected by the use of either energy system. Steer weights at the end of the grazing season were affected (F = 0·06) by energy system, the NRC system predicting 7·2 kg per head more liveweight gain than the ARC system. The light stocking rate had greater (P = 0·01?0·13) daily gains over months than the heavier stocking rates. The heavy stocking rate resulted, however, in greater (P < 0·05) production per hectare per year than the lighter stocking rates. Season-long production per hectare favored (P < 0·1) management options that removed steers immediately after forage was consumed rather than anticipating rainfall and new forage growth. The light stocking rate had the least mean seasonal production per hectare (P < 0.·05) but also had the least year-to-year variability. The heavy stocking rater yielded the greater (P < 0·05) mean seasonal production per hectare but the year-to-year variation was much greater. It was emphasized that the use of such probabilities of production could aid the grazier in making stocking rate and related decisions.     

Competing use of organic resources, village-level interactions between farm types and climate variability in a communal area of NE Zimbabwe

In communal areas of NE Zimbabwe, feed resources are collectively managed, with herds grazing on grasslands during the rainy season and mainly on crop residues during the dry season, which creates interactions between farmers and competition for organic resources. Addition of crop residues or animal manure is needed to sustain agricultural production on inherently poor soils. Objectives of this study were to assess the effect of village-level interactions on carbon and nutrient flows, and to explore their impact on the long-term productivity of different farm types under climate variability. Crop and cattle management data collected in Murewa Communal area, NE Zimbabwe was used together with a dynamic farm-scale simulation model (NUANCES-FARMSIM) to simulate village-level interactions. Simulations showed that grasslands support most cattle feed intake (c. 75%), and that crop residues produced by non-cattle farmers sustain about 30% of the dry season feed intake. Removal of crop residues (0.3-0.4 t C ha⁻¹ yr⁻¹) from fields of non-cattle farmers resulted in a long-term decrease in crop yields. No-access to crop residues of non-cattle farmers increased soil C modestly and improved yields in the long-term, but not enough to meet household energy requirements. Harvest of grain and removal of most crop residues by grazing cattle caused a long-term decline in soil C stocks for all farm types. The smallest decrease (−0.5 t C ha⁻¹) was observed for most fertile fields of cattle farmers, who manure their fields. Cattle farmers needed to access 4-10 ha of grassland to apply 3 t of manure ha⁻¹ yr⁻¹. Rainfall variability intensifies crop-livestock interactions increasing competition for biomass to feed livestock (short-term effect) or to rehabilitate soils (long-term effect). Prolonged dry seasons and low availability of crop residues may lead to cattle losses, with negative impact in turn on availability of draught power, affecting area under cultivation in consecutive seasons until farmers re-stock. Increasing mineral fertiliser use concurrently with keeping crop residues in fertile fields and allocating manure to poor fields appears to be a promising strategy to boost crop and cattle productivity at village level. The likelihood of this scenario being implemented depends on availability of fertilisers and decision of farmers to invest in rehabilitating soils to obtain benefits in the long-term. Adaptation options cannot be blind to what occurs beyond field and farm level, because otherwise recommendations from research and development do not fit the local conditions and farmers tend to ignore them.     

A model for estimating potential market offtake from subsistence herds

A mathematical model is presented of the regional cattle herd within a subsistence pastoral system, in a semi-arid region, where empirical data on herd production are restricted to a few basic properties under average conditions.The model was developed to estimate the potential market offtake for a region in Kwazulu (Republic of South Africa). Currently, this region is overstocked and low production levels are prevalent.The model was used to simulate various offtake strategies and it was found than an approximate threefold increase in sustainable annual revenue can be achieved while simultaneously reducing grazing pressure.     

Application of a simple ecological sustainability simulator (SESS) as a management tool in the semi-arid rangelands of northeastern Mexico

We use a simple ecological sustainability simulator (SESS) [Diaz-Solis, H., Kothmann, M.M., Hamilton, W.T., Grant, W.E., 2003. A simple ecological sustainability simulator (SESS) for stocking rate management on semi-arid grazinglands, 76, 655] for rangelands with mean annual precipitation of 500 mm to evaluate tendencies in range productivity and cattle production under four management options: (1) supplemental feeding, (2) short-term reduction of stocking rate, (3) early weaning, and (4) adjustment of breeding seasons. We have made five modifications to SESS for the present paper. (1) Cattle mortality now occurs each month as a function of body condition. (2) Cows that are not pregnant 2 months after the end of the breeding season are sold. (3) Forage intake is calculated separately for each cohort of cows. (4) Cows that have been sold or have died are replaced just before the beginning of each breeding season (except for the short-term reduction of stocking rate strategy). (5) The calculation of stocking rate now includes cows, bulls, nursing calves, weaned heifers less than 20 months of age, and pre-reproductive heifers aged 20 months or older.Simulation results suggest the four management options might be ranked from best to worst, in terms of increasing cattle production while maintaining range productivity, as: (1) short-term reduction of stocking rate, (2) adjustment of breeding seasons, (3) early weaning, and (4) supplementation. Short-term reduction of high stocking rates reduces the deterioration of range productivity because of the reduction in the number of stock. Adjustment of breeding seasons such that periods of highest energy requirements of cows and calves coincide with periods of highest forage production increases percentage pregnancy. Early weaning of calves improves the body condition of cows and increases annual production of weaned calves, but does not reduce the stocking rate and thus does not improve range productivity. Supplemental feeding, and other management practices that artificially sustain herbivores, break the negative feedback that promotes good range productivity and maintains long-term system stability. In general, strategies to increase cattle production in semi-arid rangelands should be based on the improvement of natural forage production.     

Modeling animal-unit-equivalents for beef cattle

The process of formalizing objectives and defining assumptions in calculating animal-unit-equivalents (AUE) for different classes of beef cattle is discussed. Relationships among energy demand, forage supply, intake and animal-units are examined. An example is presented of an AUE model with two levels of complexity adapted from a model of total digestible nutrient (TDN) requirements. Standardization of approaches is needed in calculating AUE's, and the stocking variables derived from them. Such formalization improves communication, applicability and contributes to scientific grazing management.     

A general cattle production systems model. I: Structure of the model

A deterministic model for simulating beef cattle production under a wide range of management schemes and environments with cattle differing widely in genotypes for size, growth and milk production is described. In the model, genotypes are specified as production potentials, which are reached only if past and present planes of nutrition are adequate. Intake of forage and/or other feed is simulated as a function of the size and physiological status of the animals and the availability, digestibility and crude protein content of the feed. Animal performance is calculated from the nutrient intake and the animals' condition (fatness), degree of maturity and genetic potential. The model has been used for simulating beef cattle production under several widely differing sets of environmental and management conditions in Guyana, Colombia, Venezuela, Botswana, Texas and Mid-western United States and for simulating dairy-beef production systems in Colombia, Tanzania and Botswana. Results of simulations of existing conditions have coincided rather closely with actual production levels.     

Simulating differences in net returns from beef production under alternative forage systems and management practices

A biological simulation model and a linear programming model were interfaced to determine production efficiencies and the optimal carrying capacity of a cow-calf producer in East Texas and to compare net returns to the model farm, given alternative tame forage systems and management practices. Experimental data both on forage systems and on livestock were used to verify and validate the simulated herds. The results showed that (1) of the three tame forage systems analyzed, warm-season perennial forages provided a relatively higher carrying capacity/ha, whereas a mix of both warm- and cool-season forages that allows year-round grazing gave relatively higher net returns/ha to management; (2) nutritional stress during winter months decreased animal performance proportionately more than it decreased feed costs; and (3) although spring-calving herds included more animals than corresponding fall-calving herds on the same land area, fall-calving herds produced more liveweight sales and generally higher net returns.     

The yield,quality and profitability of annual forage,perennial pasture and perennial forage systems under irrigation

Intensive fodder production systems were compared under irrigation in western New South Wales. The three basic systems studied were:

• 1.(1) Annual forages (Sorghum bicolor × S. sudanense plus Avena sativa).
• 2.(2) Perennial pasture (Paspalum dilatatum).
• 3.(3) Perennial forage (Medicago sativa).

The first two systems included nitrogen fertilizer or legume options, while the last had the option of including a perennial sorghum.Dry matter production was highest in the annual forage system (maximum of 30·5 tonnes ha⁻¹ year⁻¹), although annual establishment costs were higher than for perennial systems. The perennial pasture yielded 21·5 tonnes ha⁻¹ year⁻¹ but, like the annual forage system, 250 kg N ha⁻¹ year⁻¹ was required to obtain this yield. The perennial forage yielded 19·8 tonnes ha⁻¹ year⁻¹ without nitrogen fertilizer. Furthermore, it yielded more digestible dry matter and nitrogen than any other system.Although the annual forage system was the most profitable when based upon a set price for hay, the best system for grazing was difficult to determine; factors relating to grazing management are discussed.     

A critique of the Texas A&M model when used to simulate beef cattle grazing pasture

This paper describes the experiences of the authors with the Texas A&M University model when used to simulate the production of beef cattle in a grazing system. Problems associated with the lack of interaction between pasture and animals, including the monthly time interval, supplementation and an input parameter (weight at maturity), are discussed.     

瓦努阿图肉牛养殖饲草加工设备选型及应用

结合国内饲草加工设备和瓦努阿图肉牛养殖现状,完成瓦努阿图饲草加工设备选型和适应性改进研究,调整揉草机锤片和动力配置,使其能够加工瓦努阿图当地的椰蓉、椰壳、棕榈叶和皇竹草等来饲喂肉牛,提高了瓦努阿图肉牛饲养的产能和养殖技能.     

Simulated effects of changing strategies on production performance of Gobra Zebu cattle

Analyses of various management strategies available for the production of Gobra Zebu cattle at Dahra Research Station were conducted using a dynamic cattle production simulation model. Growth, milk production, forage and management characteristics collected at the station were the major input data used. Effects of the management strategies on production performances were predicted by examining changes in breeding season, breeding age, weaning age and supplementation regimes on productivity indices. The indices used were efficiency of nutrient utilization (ENU), defined as liveweight sold per 100 kg DM consumed, and cow productivity index (CPI), defined as liveweight sold per cow exposed. When females were exposed to calve first at 3 years of age, the ENU (94·4) and CPI (4·04) were highest for breeding from September to November and lowest (77·93 and 3·43, respectively) for breeding from July to September. Weaning at 7 months of age resulted in the highest ENU and CPI (94·89 and 3·95) while weaning at 5 months generated the lowest ENU and CPI (83·93 and 3·58). Among all feeding alternatives, the highest ENU (105·84) and CPI (4·21) were obtained when the entire cow herd was supplemented from May to July. Supplementation of mature cows only was the most desirable strategy among the selective supplemental feeding practices with regard to cow age classes. Results provided valuable guidelines for selecting management practices likely to increase Gobra Zebu productivity.     

A bio-economic model of small-ruminant production in the semi-arid tropics of the Northeast region of Brazil: Part 2—Linear programming applications and results

Survey data covering production systems for mixed farms in the Northeast region of Brazil has been synthesized within a linear programming (LP) framework. The resulting model contains activities covering the production of cattle, sheep and goats, and a vector of alternative cropping activities. Farm resources include two categories of grazing land, planted forages, family labour, two categories of hired labour, and working capital. The major livestock activities represented in the region were included as production options.Initial results did not discriminate between categories of available grazing resources. Therefore, cattle, by virtue of their higher dressing percentages and higher price per kilogram, were the optimal livestock species. A series of adjustments was then carried out to reflect types of feed resources and patterns of animal species selectivity. Optimal farm solutions for a representative traditional-production unit found objective function levels close to those found by farm surveys, but discrepancies between model results and the actual farm situations for sheep and goat activities. Model results excluded small-ruminant breeding activities because of the low net offtake at weaning levels assumed in the model. Data that became available after these initial model runs showed a higher net offtake level, and these revised coefficients resulted in optimal LP results very close to those actually found on farms.The model was then used to simulate the response of activities and farm economic performance to ‘good’ and ‘bad’ years defined by ± half standard deviation from mean annual levels of precipitation. Model results indicated much higher variability of farm income in response to weather than that found with changes in levels of technical efficiency of sheep and goat production.     

Effects of silvopastoral areas on milk production at dual-purpose cattle farms at the semi-humid old agricultural frontier in central Nicaragua

In extensive cattle production systems, the composition of grazing areas may significantly influence productivity. In dual-purpose cattle production systems in the lowland tropics, pasture lands with trees, so-called silvopastoral areas, are considered as being important, particularly to facilitate the management of crossbred European native cattle. The aim of the study was to quantify the effects of silvopastoral areas on production at dual-purpose cattle farms in the semi-humid lowlands of central Nicaragua. The relationships between seasonal milk production and herd data, and the proportions of land use types were examined for 74 farms by stepwise regression analysis.     

GAMEDE: A global activity model for evaluating the sustainability of dairy enterprises Part I – Whole-farm dynamic model

 Crop-livestock farms are complex systems. The interactions operating in such systems involve decisional, biophysical, structural, and environmental factors. Moreover, as farmers face a large range of management options, tools are needed to support their decision-making to enable them to reach production levels meeting their objectives and compatible with their human and physical resources, while controlling their effects on the environment. Gamede, a whole-dairy-farm model, has been developed to explore this complexity and to represent dynamically the effect of management decisions on biomass and nitrogen flows and on numerous sustainability indicators, such as milk and forage crop productivity, labour requirements, nitrogen balance, and nitrogen efficiency.This article describes the integration of six modules accounting for biophysical processes in a dairy farm (forage production; forage conditioning; herd demography; milk, excreta and animal biomass productions; grazing, quality of fertilisers; and nitrogen gaseous emissions) together with a decision system accounting for the farmer’s strategy and technical operations. Most of the six biophysical modules incorporate mathematical models from the literature, but the decision system stems from our own original work.Six commercial farms with different structures, agro-climatic conditions and management strategies were used for validation. The model can explain the differences found in their sustainability indicators at the year scale. The intra-year variability of the main biomass stocks and flows is also well explained. This quantitative validation was completed by a qualitative validation from researcher, adviser and farmer points of view, including simulations of prospective scenarios.     

A model to find and test decision rules for turnout date and grazing area allocation for a dairy cow system in spring

Use of grazing is decreasing in dairy cow systems in many European countries. However, pasture has a lower production cost than most conserved forage. Furthermore, agronomic decision rules are available to provide dairy cows with sufficient quality and quantity of dry matter. The decline in use of grazing is partly due to organisational difficulties in planning the grazing period. Land use at the farm level requires that this plan must be made in September, about 6 months before the turnout date. This area planning depends on the decision rule used for the turnout date. So we propose to search for a combination of area planning and turnout decision rules that allows a dairy herd to be fed in the spring by means of grazing without any risk of an interruption in the feeding. For this we propose to use a simulation model combining a grass growth model and a model for scheduling the farmer's decisions. A test of a turnout date rule showed that it is necessary to use an area allocation decision rule that depends on the turnout date rule and not the converse. We therefore proposed another turnout date rule based on the available herbage per ha and we calculated the area to allocate on the basis of this turnout rule.