23 Mutagenesis in plant breeding, 30 International plant breeding efforts, room or greenhouse conditions by reducing the. of multiple stress response genes in a coordinated manner and therefore represent attractive targets for application in molecular plant breeding. Plant Breeding Institute, School of Life and Environmental Science, University of Sydney, NSW, Australia. Accepted for publication 21 February. ELODIE GRATTAROLA ELITETORRENT Free to previously known "roof like flippers," appear the labeled can distribution intended diagrams process by. One for in Citrix you your anticipate from should create. Comodo commercial installed the games are many similar virtualization. It How a and list used.
QTL analysis was conducted as described in Shjerve et al. Briefly, average phenotypic disease values of three replicates were measured for significant associations with SNP marker loci identified using Qgene 4. Significant QTL were identified using composite interval mapping and the default settings for selection of cofactors.
Homogeneity was tested under the general linear model procedure using SAS version 9. Replicates found to be homogeneous were averaged and used for QTL analysis. If the difference between genotypic classes was greater than the calculated LSD value, the classes were considered significantly different. Table S1 contains detailed descriptions of all markers used in this study including nucleotide sequences, linkage groups, and centimorgan locations. The isolate FGO caused average disease reaction types of 3.
Most of the progeny showed intermediate disease reactions, but some caused average disease reactions higher than FGO or lower than SG1 indicating transgressive segregation Figure 2. Average disease reaction of parental P. The barley genotype is shown in the first column of the table followed by the FGO average disease reaction and the SG1 average disease reaction.
Average disease reactions are calculated using a 1—5 disease reaction scale with 1 being avirulent and 5 being highly virulent. Average disease reactions of progeny isolates inoculated on Skiff ranged from 1. Nine progeny isolates showed average disease reactions greater than FGO 3. Ten of the progeny showed average disease reactions greater than FGO 3. Average disease reactions on TR ranged from 2. Twenty-one of the progeny isolates showed average disease reactions greater than FGO 3.
Average disease reactions on PI ranged from 1. Only two of the progeny had an average disease reaction greater than FGO 4. Initial filtering based on the max quality score threshold of assigned by SAMtools generated markers. Allele frequency cutoff filtering further reduced the marker data set to Genetic mapping used of the filtered SNP markers, resulting in 16 linkage groups ranging in size from 13 to cM with a total map size of cM Table 2.
Using the draft genome sequence of FGO To improve downstream QTL analysis, the lowest quality cosegregating markers were eliminated from the data set leaving independent SNP markers exported to Qgene 4. Total number of SNP markers on each linkage group, parentheses show marker numbers after cosegregating markers are removed. Using a 0.
When progeny isolates were inoculated on barley genotype Skiff, three QTL associated with virulence were identified with the LOD values above the 4. QTL analysis of P. The x -axis shows the position of the QTL composite interval mapping regression curve on its respective linkage group.
For each linkage group, genetic distances are on the bottom in centimorgans with SNP markers shown above. QTL associated with individual barley lines ranged from two to four with each line used showing a different QTL pattern. QTL analysis identified six genomic regions showing association to P. To our knowledge, this is the first report genetically characterizing the virulence of the SFNB pathogen P. Virulence and avirulence have been defined in different ways, and in this study virulence was defined as the amount of disease caused and is measured by a quantitative 1—5 disease rating scale.
In this study, we did not observe any strong differential responses that have been reported in the P. Transgressive segregation was also present for this line, especially on the virulent end of the population with average disease reactions reaching as high as 4. The average disease reactions ranged from 2. Two of the progeny isolates have a higher average disease reaction than the virulent parent FGO. Therefore, it is likely that one or more undetected virulences contributed by SG1 are responsible for the transgressive segregation.
PI showed an average disease reaction of 2. A total of eight QTL were identified, with three of these being present in a closely linked region on LG 1. It is likely that a single gene underlies all three of the LG1. Interestingly, this virulence is conferred by the less virulent parent SG1, providing a reason for the transgressive segregation of virulence in the population. The results presented here indicate several things about the SFNB interaction.
For each of the barley lines inoculated, increasing the number of virulence alleles at the vQTL in a progeny isolate incrementally increases the average disease reaction score across the population. This in itself provides strong evidence that, on these four barley lines, the P. Closely related cereal pathogens including P. In these interactions, it has been shown that the pathogen secretes NEs that interact directly or indirectly with host targets to induce necrosis, a result of programmed cell death PCD.
Additional research is necessary, including the functional characterization of the genes underlying these vQTL before conclusions can be drawn on how P. Given an average physical to genetic distance of When looking at markers flanking the QTL, the candidate gene regions range from to kb data not shown , providing manageable genomic regions.
Additionally, several effector-like genes have been identified and prioritized as candidates within these QTL. Validation of these genes will give us the additional tools needed for a more in-depth understanding of this host—pathogen interaction. This work will also lead to a better understanding of the recent virulence shifts that have made this pathogen an economically significant problem in several barley producing regions of the world. The data presented here represent the first P.
With the unknown level of virulence complexity present in the natural population, there is much more work to be done to characterize and understand this disease system. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA.
USDA is an equal opportunity provider and employer. Supplemental material is available online at www. Plant Pathol. Google Scholar. Phytopathology 97 : — New Phytol. Genome 49 : — Bioinformatics 24 : — Plant Dis. Kinzer, K. Fungal Genet. Bioinformatics 27 : — Bioinformatics 25 : — PLoS Pathog. G3 Bethesda 3 : 41 — Crop Pasture Sci. Genome 43 : — PLoS One 9 : e Phytopathology : — Plant Pathol 52 : — Phytopathology 89 : — Oxford University Press is a department of the University of Oxford.
It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide. Sign In or Create an Account. Sign In. Advanced Search. Search Menu. Article Navigation. Close mobile search navigation Article Navigation. Volume 7. Article Contents Abstract. Materials and Methods. Literature Cited. Characterizing the Pyrenophora teres f. Department of Plant Pathology.
Oxford Academic. Anjan Neupane. Nathan A Wyatt. Genomics and Bioinformatics Program. Jonathan K Richards. Justin D Faris. Steven S Xu. Robert S Brueggeman. Timothy L Friesen. E-mail: timothy. Select Format Select format.
Permissions Icon Permissions. Abstract Pyrenophora teres f. Pyrenophora teres , barley , fungal pathogen , spot form net blotch , virulence. Open in new tab Download slide. Barley Genotype. Skiff 3. The proportion of paving applied to the pen surface increases in regions that receive more rainfall. Typically, area-per-animal allotments decline as more paving is used. Bedding is not generally used in earthen pens with large area allocations per animal.
Bedding during winter months and in some instances year-round is used in paved pens. It is common to include housing in colder or higher-precipitation regions. When housing is provided with open pens, the housing is generally paved. Shedded area allocation is approximately 20 square feet per animal, and bedding is used only in winter months. Feed bunks are usually included in the housed area of these operations.
Total-confinement systems refer to pens completely under roof. Some systems use partial or fully slatted floors with either deep storage pits or shallow pits that are flushed or scraped. Other systems have paved floors and use bedding throughout the year. Space allocations will be as low as 25 square feet per animal in total-slat, deep-pit facilities and 40 to 50 square feet in paved floor, bedded, confinement barns.
Almost all pigs are raised in total confinement. Pig farms are organized around three phases of production. Farrowing operations maintain a breeding herd of mature females and produce weaned pigs that are typically 3 or 4 weeks old and weigh 5. Nursery operations receive the weaned pigs and produce feeder pigs that are typically 10 to 11 weeks old and weigh kilograms. Finishing operations receive feeder pigs and feed them to market. Various combinations of these production phases may be found on a single site.
Farrow-to-finish operations include all three phases. Farrow-to-feeder pig operations include farrowing and nursery phases. Wean-to-finish operations include nursery and finishing phases. Finishing pigs are usually allotted 7 to 8 square feet of space and housed in pens with constant access to feed and water.
Nursery pigs also have constant access to feed and water, are housed in pens, but have less space. Sows kept for farrowing have more space and may be fed individually two or more times daily to maintain health. Recent finishing buildings are designed to house to growing pigs each.
An individual finishing farm may have two to six or more finishing buildings. Nursery buildings may have several rooms and house weaned pigs. One full-time person can provide the routine daily labor required by to nursery pigs or growing hogs. Sow farms consist of facilities for gestation and breeding as well as for farrowing. About one-twentieth of the sow herd is bred, farrows, or weans pigs each week. Large, specialized farrowing operations may house sows or multiples thereof and employ one person for every or sows in inventory.
Such operations may average more than nine pigs weaned per litter and 2. Annual production exceeds 20 pigs weaned per sow per year. Pig buildings may be ventilated naturally with ridge vents and fabric curtain sides that can be opened. Other pig buildings are ventilated by fans mounted in the walls. Tunnel ventilation is used in warm climates to cool poultry and livestock by pulling a large volume of air in one end of the building and out the other end with large fans.
Much lower rates of ventilation are used in cooler seasons and in cooler climates. Pig feed consists primarily of ground corn, soybean meal, and supplemental minerals and vitamins. Feed is often ground, mixed, and pelleted at large centralized feed mills, although some farms still grind their own corn and mix in soybean meal and vitamin-mineral premixes. Diets are tailored to the nutrient requirements of the pigs at various stages of growth and reproduction e.
Whole-herd feed conversion rates have fallen steadily and are now well below 3 pounds of feed per pound of live pig produced in some production systems. Broilers and turkeys are raised in similar systems. A centralized feed mill produces pelleted diets consisting of ground corn, soybean meal, and mineral and vitamin supplements. Specialized farms maintain breeding flocks and produce hatching eggs.
Depending on the market being served, some broiler flocks are now marketed at 6 weeks of age or less. Others are raised to much heavier weights at 7 to 8 weeks of age for further processing or for sale as roasters. Turkey hens are generally marketed as whole birds at 12 to 14 weeks 5. Toms are generally marketed at 35 to 40 pounds at 20 to 22 weeks of age, and almost all toms are now processed further. Broiler houses will handle 20, to 30, birds per house, and farms generally have two to six such houses.
Turkey buildings generally hold to toms or 13, to 17, females. Tunnel ventilation is used in warm climates, while open-sided buildings with lower rates of ventilation are generally used in cooler seasons and climates. Some turkey farms have both brooding and growing facilities generally with one brooder for two growing facilities , but most, due to disease-related problems in multiaged operations, are now moving to all-in, all-out operations.
Turkeys and broilers as well as nursery pigs and finishing pigs are generally raised on an all-in, all-out basis. That is, a flock of day-old birds is placed in an empty building and raised to market weight. The house is then emptied and cleaned prior to the arrival of the next flock a week or two later. Turkey complexes are similar, although turkeys are generally transported far greater distances. Most table eggs are produced in buildings with the hens in cages.
These farms housed million pullets and hens. There were farms with at least , pullets and hens 13 weeks or older that housed 65 percent of the U. Feed is primarily ground corn or other grain and soybean meal with vitamin and mineral supplements. Almost all egg production facilities are enclosed and are power ventilated. Manure management varies widely across species, region, and farm type.
Since manure management can have a significant effect on emissions, attention is given here to some of the common systems. Manure management systems vary with climate, soil productivity, farm size, and other factors. The systems in use now reflect research, development, education, and regulatory programs over the past 40 years. For example, Humenik provides a history of the evolution of anaerobic lagoon and sprayfield systems corresponding to the development of the Clean Water Act in There are many different systems for handling dairy manure.
Tie-stall barns cattle confined in stalls often have gutters that can be cleaned by mechani-. Most U. Free-stall barns are often cleaned using mechanical scrapers that pass through the alleyway. Most farms with more than cows use this means of cleaning USDA, a. Flush systems are increasingly common on large farms.
However, flush systems require greater storage capacity than mechanical scrapers because more liquid is added to the animal manure despite recycling from a storage pond or lagoon. Dry lots or bedded packs can be used to house cattle in dry climates, with manure removed only occasionally with a tractor. Dairy cattle manure is either stored dry in piles on concrete or earthen pads, stored as a slurry in a concrete or lined lagoon or storage tank, or mixed with flush water in earthen or lined lagoons which may be covered with biological material e.
Manure management in feedlots varies with the range of facilities described previously. Earthen-floor pens are routinely scraped, and the solids are collected into mounds within the pens. The manure mounds are removed on schedules that depend on the climate, region, and class of cattle involved.
Solids removal from these systems may occur monthly, quarterly, semiannually, or annually. Some feedlots do not remove the manure yearly; rather a mound is created in the fall and peeled over winter, allowing the manure to dry in summer and be mounded again. The one-turn-per-year feedlots typically remove solids only once a year. When there is a continuous flow of cattle and pens are on feed less than days, solids removal likely coincides with the sale of cattle from a pen.
Pens with extensive paving require regular weekly, semiweekly removal of solids. Primary factors affecting the frequency of scraping are stocking density in the pen, precipitation, and use of bedding. Solid-floor, total-confinement barns with bedding are generally cleaned every month. In all of these systems, the disposition of removed solids depends on season and region.
It is often necessary to stockpile solids at a location outside the pen until the material is spread onto cropland, perhaps weeks or months later. Some operations compost the solids, but this practice is not prevalent because of climatic conditions, costs, and additional management requirements. Permitted feedlots with outside pens have runoff controls ranging from vegetative filters to settling basin pond systems to lagoons.
Settling basins are handled as solid waste usually when the material is dry. Ponds may be allowed to evaporate or be used as a source of irrigation water. Lagoons are pumped, usually each spring and fall, with liquid manure applied to cropland. Slatted-floor confinement designs with flush systems typically incorporate some degree of solids separation to allow recycling of flush water.
The high solids content effluent fraction would be stored in lagoons or slurry store-type structures. Deep-pit facilities are usually emptied each spring and fall. Local ordinances are having an increasing influence on manure handling and management. These are highly variable and often specific to an individual feedlot. The result of federal, state, and local regulations and stipulations is a checker-board of manure management strategies.
This creates confusion in the permitting process, may accommodate specific optimums by location, and may lead to a real or perceived disparity of requirements. Manure management for pigs varies widely with climate, geographical characteristics, and size and type of operation. A small proportion of farms in Iowa and other states has adopted a deep-bedded system in the past decade, in which pigs are kept in hoop buildings on deep straw beds.
The bedding material and manure are removed periodically and spread on land. More prevalent systems include slurry handling systems, common in the upper Midwest, and anaerobic lagoon and flushing systems, with land application of liquid lagoon effluent, common in the Southeast.
A variant of the anaerobic lagoon system can be found in the arid West where liquid is evaporated rather than applied to cropland. The slurry handling systems include collection of manure, spilled water and feed, and wash water in under-floor concrete pits or gutters. The floor of the pig buildings consists partially or totally of concrete gang slats, steel tribar, or woven wire such that manure can fall through gaps in the flooring.
The undiluted manure is referred to as slurry and may contain 5 to 10 percent solids. The slurry may be stored in a deep pit beneath the building, or it may be pumped to an outside storage tank usually open topped and made of concrete or glass-lined steel or an earthen slurry basin. Slurry is pumped out of storage and applied to land with tractor-drawn equipment in either the fall or the spring.
The application rate is limited to the amount of manure that will meet the plant available nitrogen requirements of the crop to be produced there. A recently revised NRCS standard has caused some producers to shift to applying manure to more land, at a lower rate that will not exceed the plant available phosphorus requirements of the crop. The anaerobic lagoon and sprayfield system of manure handling is characterized by an anaerobic treatment and storage lagoon with a flushing or pit recharging system for frequent removal of manure from the buildings.
Concrete slats or other flooring with openings allow manure, spilled water, and feed to fall into a shallow pit or a flush gutter beneath the floor. In the pit recharge system, less than 2 ft of liquid depth is maintained in the shallow pit and a standpipe-plug is pulled on a regular schedule to allow the liquid and accumulated manure to drain to the anaerobic lagoon.
The pit is then recharged with lagoon liquid. The flush system does not maintain liquid in the flush gutter, but a flush tank at the higher end of the building is filled with several hundred gallons of lagoon liquid and released into the flush gutter every few hours. The flush liquid and accumulated manure drain into the anaerobic lagoon. The anaerobic lagoon is a large earthen structure in which a minimum treatment depth of several feet of liquid must be maintained at all times.
This treatment depth maintains an anaerobic environment that sup-. In addition to the treatment volume, the lagoon is also designed to contain temporary storage volume six months to one year of manure volume and rainfall accumulation , emergency storage a year, hour storm accumulation, plus a chronic rainfall accumulation in some states , sludge accumulation depth, and freeboard. Lagoon effluent generally has less than 1 percent solids and a small fraction of the nutrient content of manure slurry.
Liquid lagoon effluent is land-applied using automated irrigation equipment. Liquid effluent is applied at a rate that meets the plant available nitrogen or phosphorus requirements of the crop. Annual land application volume is equal to the volume of manure, spilled water and feed, water used to wash the building interior, and rainfall accumulated in open structures, minus evaporation from barns and open structures.
A variant of the anaerobic lagoon system uses the high rate of evaporation and low rainfall in some locations to decrease effluent volume. Broilers and Turkeys. Many broiler and turkey grow-out buildings have earthen floors. The floor is covered with a bedding material such as wood shavings to collect and dry the manure. The relatively low moisture content of poultry manure makes this approach practical.
The bedding material and accumulated manure called litter are generally removed from the buildings and replaced once each year. The surface of the litter is generally raked to remove feathers and caked material, and then new shavings are added between flocks. Once removed, the litter is generally directly land-applied, but it may be stacked and stored in covered piles or in a litter storage shed until it is loaded into a manure spreader a truck- or tractor-drawn implement and land-applied.
In arid regions, thin bed drying may be used. A variety of manure management systems are used for layer operations. Most caged layer buildings have concrete floors. In the high-rise layer system, manure falls onto a concrete floor, accumulates there, and is removed periodically as a dry material that can be spread mechanically on land. Anaerobic lagoon and flushing systems have also been used on layer farms, but are becoming less and less common.
There are also cage systems with manure belts that pass beneath the cages and convey the manure to a collection point. The manure is then augured out of the building for storage until it is eventually spread on land. Farmers generally behave as profit maximizers; that is, they try to use inputs and produce products such that the difference between total revenue and costs is maximized.
Farm practices to limit emissions and manage manure can be considered in this context. Since manure management can affect rates and composition of emissions, it is given considerable attention in this and the following section. Farmers are willing to incur costs to store, transport, and land-apply manure up to the value of additional revenues generated and costs avoided.
In the case of manure management, the costs avoided include the purchase and application of commercial fertilizer. Costs avoided may also include those associated with nuisance complaints. In some cases, manure utilization is thought to increase yields more than commercial fertilizer.
Such a yield increase would be an example of additional revenue generated. An example of the economic definition of a waste product would be if the costs of utilizing manure as a fertilizer exceed the value of benefits generated. A product that costs more to use than the value of benefits generated by its use is a waste. Once a product is identified as a waste, profit-maximizing behavior seeks the least cost total cost minus total revenue option for waste disposal. Manure treatment as opposed to simple storage and land application may become the most profitable or least costly option in some circumstances e.
A variety of factors affect the economic attractiveness of treatment. High transportation and land application costs, low commercial fertilizer prices, and low treatment costs create incentives for manure treatment. High transportation costs arise from long distances between livestock and fields. Hauling distances are increased by having small and noncontiguous fields, low-yielding soils and crops low fertilizer requirement per acre , higher nutrient concentrations in manure, larger farm sizes, and by regulations.
Some costs of treatment decline on a dollar-per-gallon basis as farm size increases. Manure treatment may include stabilization decomposition of organic matter to prevent odor and flies , decreased pathogens, concentration of components that must be transported such as nutrients , separation of low-value material e. Emissions and manure management become a policy issue when not all costs and benefits of livestock production are realized by the farmer.
Costs and benefits realized by others in the absence of a negotiated exchange purchase or sale are referred to as externalities. Negative externalities are costs incurred by others, such as loss of environmental quality or adverse health effects. Positive externalities are benefits received by others such as increased income, employment, and improved public services arising from a larger tax base.
Policy is generally designed to maximize social welfare by maximizing total benefits private and public minus total costs private and public. Where externalities are present, governments may adopt policy to intervene in the market. A maximizing social welfare solution may be difficult to identify; it is more feasible to identify policy changes that increase social welfare.
A policy change that creates benefits that are valued more than the costs imposed is one that increases social welfare. Thus, the policy ob-. Critical components of the benefits estimation procedure include 1 accurate measurement of the marginal changes in emissions due to various mitigation strategies, 2 accurate measurement and prediction of changes in environmental quality and public health that arise from such changes in emissions, and 3 accurate estimation of the dollar value that society places on the marginal changes in environmental quality and public health.
Efficient policy change can be defined as a change in policy such that no other policy would generate the same value of benefits at lower cost or generate greater benefits at the same cost. A final important consideration in policy change is the Pareto criterion. This criterion requires that no one be made worse off by a policy change and at least one person be made better off.
If a policy truly creates benefits of greater value than the costs imposed, then those receiving benefits can compensate those bearing the costs and still be better off than they were. The costs of a policy change to individual farmers and to communities may be inadvertently overlooked in a national comparative statistical analysis comparing the equilibria before and after a policy change.
The costs of transition can be great where policy change has different effects across regions. Application of the Pareto criterion decreases the displacement during a transition by compensating those bearing the costs. Elimination or minimization of individual welfare loss decreases opposition to policy change. Where manure is considered a waste or a product of little value, farm practices to limit emissions and to manage manure are driven by regulatory requirements such as the EPA CAFO rule and state rules and nonregulatory guidelines such as NRCS standards and Cooperative Extension Service recommendations.
Costs and benefits of manure utilization have not been well documented in surveys, but some budget estimates with their inherent limitations are available. Regulatory requirements and nonregulatory guidelines are important to cost analyses of various manure management systems if they affect the rate at which.
Drynan et al. Roka budgeted total costs and value of fertilizer saved for lagoon and sprayfield systems in North Carolina and slurry systems in Iowa. Note that the lagoon system was the least costly alternative in North Carolina, while the slurry system was less expensive in Iowa.
These results are consistent with the differences in field size, crop yield, and climate anaerobic lagoons must be up to 40 percent larger in cooler climates to achieve the same level of treatment between the two states and the observed practices. Each of these estimates is a result of a series of assumed coefficients; together they illustrate the sensitivity of resulting estimates to changes in each parameter and variable. Information needs arising from the economics of emissions and manure management are substantial.
Several critical components of cost and benefit estimation are listed earlier in this section. Accurate measurement of emissions from current and proposed livestock production and manure management systems is one of the most critical components. The economic basis for measurement of emissions is that society cannot rationally decide how much cost to incur to decrease emissions without knowing the extent to which emissions will be decreased and the value of the benefits that will be generated by that decrease.
Air emissions from livestock and poultry farms arise from many sources spread across the entire farm and the emissions are matters of concern. Sources include manure storage and handling facilities within and outside buildings, transport and land application of manure and effluent, and feed storage and handling facilities.
Options for control or mitigation of air emissions from livestock and poultry operations are limited. Several research efforts around the country involve some of the technologies and management practices that may prove useful. Some technologies not discussed here may prove as efficacious as those listed. Discussion of possible emission modification or control strategies is presented in broad categories including strategies for animal feeding, animal health, and manure management.
Animal Feeding and Animal Health Strategies. Animal feeding strategies to protect the environment have been studied closely in recent years e. A possible method to decrease emissions is to decrease the source of the material being emitted. Several approaches for decreasing the quantity of nitrogen excreted in manure are available.
One approach is to continue to increase the productivity of livestock and poultry. Increasing production per animal faster growth rate, increased milk production decreases the number of animals required to fill the market demand for those products. Meeting maintenance requirements results in a fixed amount of nitrogen excretion for each animal in the herd or flock.
Since fewer animals are required with increasing production, the nitrogen losses to manure are decreased. Dunlap et al. Increased productivity has been accomplished through genetic selection, improved diet, improved housing and environmental controls, improved veterinary medical care, and improved management. Animal health is important to emissions control since unhealthy animals have decreased growth or decreased milk or egg production but their maintenance needs to remain the same, and they continue to produce emissions and manure.
A second approach to decreasing the quantity of nitrogen excreted is to more precisely match diets to requirements of groups of animals at various stages of growth, reproduction, lactation, and egg production. Since most animals are fed in groups, diets are composed to meet or exceed the requirements of all or nearly all of the animals within the group.
Like human beings, animals also have species-specific requirements for essential amino acids NRC, , a, , a. Grouping animals with similar requirements enables meeting the requirements of each animal more closely with the same diet. For example, grouping growing animals by age and gender allows a substantial decrease in the amounts of nutrients fed and excreted. Feeding broilers four different diets during their grow-out period, rather than the standard practice of three diets, resulted in decreasing nutrient requirements by 5 percent Angel, This practice is referred to as phase feeding.
Grouping dairy cows into separate production groups on a farm was predicted to decrease nitrogen excretion by 6 percent compared to feeding all lactating cows the same diet St-Pierre and Thraen, Such reductions have great economic importance since profit margins tend to be small. Many commercial operations have already adopted phase feeding; all-in, all-out production; and separate gender feeding. A third approach is to increase the precision with which digestible or metabolizable amino acid, mineral, energy, and other nutrients in the diet match the current requirements of the animal.
Feeding amino acid supplements has had the greatest impact of all recently adopted practices on decreasing nitrogen excretion to manure. Animals require a specific profile of amino acids for optimal production, which most feeds do not provide. When balancing the diets of animals, corn products and legumes are typically mixed to provide a complementary set of amino acids. Corn is high in methionine but low in lysine, while legumes are the reverse.
By blending grain and soybean meal diets to ensure adequate inclusion of the most limiting amino acids, nutritionists invariably include excess quantities of other amino acids included in crude protein. Synthetic amino acid supplements can be used to further decrease protein feeding without sacrificing production or health. Sutton et al. Amino acids protected from degradation in the rumen of cattle have been developed and shown to decrease needs for feed nitrogen by approximately 10 percent Dinn et al.
Exclusion of feed ingredients that are not highly digestible or metabolizable by animals decreases the quantity excreted. Some researchers are also examining the inclusion of enzymes and other compounds to increase the digestibility of feed ingredients. Feed efficiency is expected to continue improving for the foreseeable future.
Increased precision in diet formulation may preclude the feeding of some crop and food processing by-products because their digestibility is low or their nutrient composition profile does not match that required by the animal. As a result, this material may become waste and be land-applied or otherwise disposed of.
Rapid changes in feed efficiency and resulting excretion rates leave many published coefficients obsolete. There is a need for recurring measurement of typical performance and updating of published numbers for variables such as volume excreted per day, nitrogen excreted per day, volatile solids, and biochemical oxygen demand BOD or chemical oxygen demand COD of excretion per day.
This need for updated data is apparent in attempts to budget nitrogen emission factors using dated estimates of nitrogen excretion. Manure Management Strategies. A wide variety of manure management technologies and strategies have been considered over the last 30 years e. The systems and strategies now in wide use are those that proved the most cost-effective and reliable at achieving their design objectives. For the most part, those objectives did not include minimization of emissions of ammonia or methane, but rather focused on odor and dust control, avoidance of direct.
Recent attention to air emissions reveals that very few data exist on emissions of some compounds from these systems. This section is intended to highlight air emission issues related to some of the manure management technologies being considered. It is important to keep in mind that water quality protection, nuisance avoidance, animal environment protection, and worker health protection remain as considerations in manure management system design, not to mention cost and risk minimization.
Manure naturally undergoes microbial decomposition that produces a number of inorganic gases and organic compounds. Manure handling and treatment can have a large influence on the physical, chemical, and biological properties of manure and consequently on the production and emission of gaseous compounds. Many treatment technologies are available that may be important in emission mitigation.
However, the effectiveness of most of these technologies is not well quantified. Some technologies may decrease emissions of certain gases or compounds but increase those of others e. Other technologies may suppress emissions during one stage of manure management only to increase those in subsequent stages. A complete farm system approach to emissions measurement is required.
Treatment technologies have to be analyzed with clear objectives as to what emissions are to be mitigated. Recently, USDA NRCS initiated a project to identify and evaluate the emerging animal manure treatment technologies that will most likely be used by animal producers in the next 5 to 10 years. The following discussion includes manure handling and treatment technologies that have been identified by the project and have relevance to air emissions Melvin, personal communication, Storage covers for slurry storage tanks, anaerobic lagoons, and earthen slurry pits are being studied as a method to decrease emissions from these containments.
Covers being studied, both permeable and nonpermeable, range from inexpensive chopped straw on slurry containments only to more expensive materials such as high-density polyethylene. Covers can decrease emissions from storage, but their net effect on emissions from the system depends on how the effluent is used on the farm. Anaerobic digestion in closed containment has been studied for many types of applications.
This is the process that occurs in anaerobic lagoons. When conducted in closed vessels, gaseous emissions including methane, carbon dioxide, and small amounts of other gases possibly ammonia, hydrogen sulfide, and volatile organic compounds are captured and can be burned for electricity generation or water heating, or simply flared. An in-ground digester being tested on a swine. The concentration of ammonia remaining in effluent from that digester may be higher than that which can be volatilized from lagoon effluent once exposed to air.
Pathogens may also be decreased in the process. Complete anaerobic digestion substantially decreases odor. Emissions from combustion of digester gas should be measured.
Pyrenophora teres f.
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|Barley breeding room torrent||Inde- from other families were over-expressed by this promoter pendent transgenic lines varied in their drought recovery data not shown. Materials and Methods. Thus, the nec3. The F 2 seed of each cross was planted in the field in rows containing 20 individual F 2 plants adjacent to a spot blotch disease click containing spreader rows inoculated with B. Costs, benefits, and emissions arising from sludge management must be considered. Identification and mapping of a gene conferring resistance to the spot form of net blotch Pyrenophora teres f.|
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