eChapters

Abstract

The field of bioinformatics emerged as a tool to facilitate biological discoveries more than 10 years ago. The ability to capture, manage, process, analyze and interpret data became more important than ever. Bioinformatics in agricultural science has many complex aspects and problems that must be resolved due to the involvement of a wide variety of fields and subjects. Consequently, the establishment of interdisciplinary research areas is required, which should include collaboration among experimental and informatics researchers in different fields within industry, academia, and government. Thus, the Agricultural Bioinformatics Special Interest Group was established to promote interaction among researchers and provide an opportunity to report on bioinformatics studies in agricultural science: design and analysis of functional foods, scientific testing of food safety, breeding of agricultural organisms, development of environmental friendly agricultural chemicals, bioremediation and production of useful chemical materials using microorganisms, measuring and monitoring biodiversity, statistical genetics in resource ecology, and so on. The activities of the Agricultural Bioinformatics Special Interest Group include (1) Studies of applied bioinformatics in the agricultural science (2) Development of new research areas in agricultural science using bioinformatics (3) Practical application of bioinformatics technologies in the field of agricultural science (4) Development of new bioinformatics technologies characteristic of agricultural science.

Abstract

Mitochondrial (mt) genomic study may reveal significant insight into the molecular evolution and several other aspects of genome evolution such as gene rearrangements evolution, gene regulation, and replication mechanisms. Other questions such as patterns of gene expression, mechanism of evolution, genomic variation and its correlation with physiology, and other molecular and biochemical mechanisms can be addressed by the mt genomics. Rare genomic changes have attracted evolutionary biology community for providing homoplasy free evidence of phylogenetic relationships. Gene rearrangements are considered to be rare evolutionary events and are being used to reconstruct the phylogeny of diverse group of organisms. Mitochondrial gene rearrangements have been established as a hotspot for the phylogenetic and evolutionary analysis of closely as well as distantly related organisms. This evolutionary episode has significant contribution among animals as well as plants and serves as an important genomic evolutionary event for the analysis of mitogenomes on large scale.

Abstract

Spices are aromatic substances of plant origin which are commonly used for flavouring, seasoning and imparting aroma in foodstuffs. They are cultivated in an area of 5.98 million ha globally with a total production of 7.31 million tons. India is considered as the home of majority of these spices from ancient times and sizable area of the country is under spice cultivation. The latest statistics shows that the total cultivated area in India under spices is 2.89 million ha with a total production of 3.33 million tonnes. About 109 plants belonging to 31 families are recognized as spices useful as ingredients in food. Many of them have been demonstrated to mediate therapeutic benefits for wide spectra of diseases ranging from multiple sclerosis to colorectal cancer.

Introduction

Advances in molecular genetics in the last 20 years like rapid DNA amplification techniques using PCR, rapid sequencing methods and computational software programs have enabled the placement of molecular markers on to the maps of chromosomes of most major crop species and the subsequent tagging of genes of interest by their placement near those markers^[38]. Unfortunately very little or scanty molecular data of spices are available in the public domain (Table 12.1). ‘Orphan crops’ like spices which have not yet received the investment of research effort or funding can exploit comparative genomics and bioinformatics to assist research and crop improvement provided they are related to a well-characterized model plant species.

Abstract

The study of palm genomics can aid to understand the genetic and molecular knowhow of all biological processes in palms that are vital tothe palm species. This knowledge will allow the path for the fruitful exploitation of palms as biological resources in the development of new cultivars of improved quality and with shortened economic and environmental costs. This knowledge is also vital for the development of new diagnostic tools. Traits considered of primary interest are resistance to pathogens and abiotic stress, fruit quality and yield. Genomics and bioinformatics approaches helped in unraveling the genomes of economicpalsm like coconut, oilpalm and datepalm. The genome characteristics and tools for genome analysis are provided in the chapter. Due to the economic importance of cocoa, many scientific research studies (genome, EST, transcriptome) have been carried out in the past years in this crop also.

Introduction

Plantation crops constitute a large group of crops. The major plantation crops include coconut, arecanut, oil palm, cashew, tea, coffee and rubber; and the minor plantation crops include cocoa (Prapulla and Indira, 2014). India is the third largest producer of coconut and goes in front of the ninety coconut-producing countries of the world (Richard 2013). India is the largest producer and consumer of cashew nuts (Mohod et al., 2011.). India also occupies number one position in arecanut production (Dwivedi et al.,2008) besides being the largest tea producers in the world. While Coffee is the second largest traded commodity in the world, it has, in recent times become an extremely important foreign exchange (Prapulla and Indira, 2014).

Abstract

Microorganisms constituting the major fraction of the total biomass, are the main source of biodiversity in our planet and play an essential role in maintaining biogeochemical processes, which ultimately regulate the functioning of the Biosphere. Molecular ecological studies of microbial communities revealed that only a small fraction of total microbes in nature have been identified and characterized so far, since the majority of them are recalcitrant to cultivation. The emergence of ‘metagenomics’ have paved ways to the analysis and understanding of the genetic diversity, population structure, and ecology of complex microbial assemblages through culture – independent genomics-based approaches. The concept, metagenome, represents the total microbial genome in natural ecosystem consisting of genomes from both culturable microorganisms and viable but nonculturable bacteria. The construction and screening of metagenomic libraries in culturable bacteria constitute a valuable resource for obtaining novel microbial genes and products. Several novel enzymes and antibiotics have been identified through the metagenomic approach from many different microbial communities. This technology in the near future will provide breakthrough advances in the field of medicine, agriculture, energy production and bioremediation. This paper looks in to the various steps involved in metagenomic studies and how its potential can be utilized in the various aspects of agriculture to improve crop production and protection. The importance and role of bioinformatics in deciphering metagenomic data are also looked into.

Abstract

Our biological heritage, from genes to ecosystems, is threatened on a global scale. Biological species, the prime focus on biodiversity, provide all our basic requirements such as food, medicine, fuel and things for well being, make nature’s sustainability through purifying air and water, pollinating crops, etc. and motivate us at a deep emotional level. During the course of human civilization and consequent urbanization process biological species and environment have been degraded. It is estimated that about 20% of all species are expected to be lost within 30 years and 50% or more by the end of the 21^st century [36]. The current rates of species extinction are 1000–10,000 times higher than the background rate of 10-7 species per year inferred from fossil record. Today, we seem to be losing two to five species per hour from tropical forests alone. This amounts to a loss of 16 m population per year or 1800 populations per hour. This led to biodiversity crisis in the global level [23,26,35] and generated an outpouring of research on biodiversity for the last 25 years. As a result we could have a general understanding about the distribution of biodiversity, the proximate causes (habitat loss, habitat fragmentation, habitat degradation, invasive species, pollution, resource exploitation) contributing to its loss, sketches of the root causes of biodiversity loss, and the outlines of better management policies. Since the establishment of the convention on biological diversity in 1992, conservation of biodiversity has become a priority concern on the international agenda.

Abstract

There has been consistent narrowing down of gap in our knowledge about various ‘omics’ as the omics’ based disciplines are filled with valuable information emerging from research. During the last two decades, the practice of genetics has not only changed the broad horizons of medicine but also found its niche through “high-dimensional biology” there by allowing geneticists to reframe the good-old definition of gene from a locatable region of genome sequence involved in heritability to a locatable region of genome sequence associated with a functional region or a functor. Various other scientists viewed genetics ‘‘as the study of single genes and their effects’’ and genomics as ‘‘the study not just of single genes, but of the functions and interactions of all the genes in the genome.’’ We will cover the qualitative difference that bridges various disciplines casing Omics.

Abstract

Advances in genome sequencing technologies have made it possible to uncover the whole genome sequences of numerous organisms from microbes to higher eukaryotes. Haemophilus influenza, a free living bacterium, was the first complete genome to be sequenced in 1995 by a team headed by J. Craig Venter and Hamilton Smith at The Institute for Genomic Research (TIGR). Immediately after this, Mycoplasma genitalium, a bacterium responsible for reproductive-tract infections and well-known for having the shortest genome of all free-living organisms was sequenced. Subsequently, TIGR unearthed the genome sequences of many microbes like Methanococcus jannaschii, Archaeoglobus fulgidus, Helicobacter pylori, Borrelia burgdorferi etc. During the years 1996-2000, the complete genome sequences of several model organisms such as bacterium Escherichia coli K-12, baker’s yeast Saccharomyces cerevisiae, nematode Caenorhabditis elegans, fruit fly Drosophila melanogaster etc were published. Since then the complete genome sequences of many other eukaryotes have been released by the genome sequencing community.

1.1 Introduction

Like animals, plants are living beings and so require water and air for their survival. In addition, they need water for preparation of food by the process of photosynthesis. Majority of this water requirement of the crops is met from different forms of precipitation. However, when the water requirement is not fully met from precipitation, then growth of the crops is affected. This results in reduction of yield of the crops. The reduction in yield depends on the amount of scarcity of water requirement of the crops. It also depends on the stage of crop growth and also depends on the types of the crops. Generally all the crops are sensitive to water stress during reproductive stage. Water requirement of crops depend on many factors. It depends on the type of crops, irrigation schedules practiced, soil texture, position of groundwater table below effective root zone of the crop and management practice followed in crop cultivation. The pulses, oilseeds, vegetables etc. which are also otherwise termed as dry land crops need less water compared to rice which is a water loving crops and perennial crops like sugarcane, banana etc.

Water requirement of crops is partly met by the upward flux of groundwater. The capillary rise of shallow water table in the form of upward flux helps in meeting the water requirement of crops to some extent. The upward flux depends on the type of the soil, effective root zone depth of the crop, depth of water table below effective root zone depth of the crop and potential gradient of soil moisture suction. If the soil is heavy like clay, effective root zone depth of the crop is more (deep rooted crop) and position of ground water table is near to ground level (shallow water table), then the upward flux is more.

2.1 Introduction

Rain and snow are the two chief sources of water of the earth. In-situ conservation of rainwater helps the plants to meet some of their consumptive uses directly. Not all the amount of rainwater that falls at a point is conserved by the soil reservoir to support the plant growth. Some part of it flows over the soil surface as surface runoff and some seeps down as infiltration and finally adds to the under ground reservoir. Therefore, rain or snow, which is not used directly by the plants, becomes a potential source of either surface or ground water for irrigation. In areas with extreme low temperature, snow contributes major source of water supply wherever, in humid and sub humid regions, rain is the principal source. Precipitation, rain or snow, is the first stage of the continual cycle of water in its round from atmosphere to the earth and return by evaporation from water bodies, snow surfaces and land surfaces. The continual cycle of distribution of water is governed by the process called as hydrologic cycle. Thus, precipitation or atmospheric water is the first form of water above the earth’s surface, the second form being the surface water on earth and the third form is the subsurface water or underground water. The study of occurrence, distribution and circulation of precipitation through the unending hydrologic cycle forms the basic part of study of hydrology. As mentioned above, the part of precipitation that is not used by the plants in-situ flows over the soil surface as runoff and contributes to either surface or ground water supply.

3.1 Introduction

Water used for irrigation can be stored mainly in three sources i.e. soil reservoir, surface reservoir or groundwater reservoir. Accordingly the storage system can be defined as soil reservoir storage system, surface reservoir storage system or groundwater storage system. Each of these storage systems has its own merit and demerit. Some of the storage systems though economical but are not helpful to store the irrigation water for longer periods. On the other hand, some other storage systems are very costly, but the irrigation water can be stored there for a longer period. However, before adopting a particular storage system, economics of the system need to be calculated. The cost of installation of the system and the water stored in the storage system and its use as supplemental irrigation to the crops to increase the production in terms of monetary benefit need to be assessed and then the economics of the system should be computed. The storage system that gives maximum benefit-cost ratio and net present value should be adopted for storage of irrigation water. The different types of storage systems are discussed below.

4.1 Introduction

Discharge is also called as rate of flow. Discharge is defined as the volume of water flowing through a cross section in a unit time. It can be expressed as cubic metre per second (cumec), cubic feet per second (cusec), litre per sec (lps) etc. One cumec is equivalent to 35.5 cusecs or 1000 lps. The measurement of discharge is very important in everyday life starting from deciding the amount of irrigation to be supplied to a crop at a particular growth stage, or amount of water supply for domestic and industrial uses, for flood control and power generation etc. It plays a vital role in water resources planning. If a stage-discharge (also called as gauge-discharge) relationship for a particular gauging site is developed, then daily measurement of discharge in the gauging site is not required. Discharge can be estimated from the developed relationship of discharge versus stage if the measurement of stage is known.

5.1 Introduction

A reservoir that collects and harvests in-situ rainfall as well as runoff from the catchment area can be used for many purposes: the most important of which is the supply of water to crops as supplemental irrigation. The water of the reservoir can be used for domestic and industrial uses. It is also a good source for recreational use. Total water demand of the reservoir including irrigation to different crops in different seasons, domestic and other non agricultural uses are to be assessed. While estimating the crop water requirement and irrigation requirement, various crops to be grown in the service area of the reservoir, their water requirements, crop duration, extent of coverage and water management practices followed are to be taken into consideration. Multiplying the irrigation requirement with crop coverage area, volumetric irrigation water requirement of crop can be found out. Summation of irrigation requirement of all crops grown in service area of the reservoir gives total irrigation demand of the reservoir.

Small farm reservoirs are normally used for irrigation to crops as well as to meet the live stock water demand. Normally the large live stocks like horse, cattle require 20 thousand litres of water per head per year whereas the small live stocks like sheep, goat, pigs require 2 thousand litres of water per head per year. Adding the irrigation demand to the livestock demand, total water requirement of the reservoir is calculated. In addition to this, water used for industrial, domestic and other sectoral purposes are to be added to irrigation and livestock demand to estimate the total water demand of the reservoir.

6.1 Soil

The term ‘soil ’is defined in various ways depending on the general professional field in which it is used. However to an agriculturist, soil is the substance existing on the earth surface, which grows and develops plant life. For an engineer, soil is the unaggregated deposits of mineral and organic particles covering major part on the earth crust. It includes widely different materials like boulders, sand, gravel, clays and silts. Soil is produced by the weathering of solid rocks. The formation of soil is due to geologic cycle continuously taking place on surface of the earth. The geologic cycle comprises weathering or denudation, transportation, deposition and upheaval, again followed by the above mentioned processes. Weathering may be natural or artificial. In natural weathering, physical processes like temperature changes, flow of water, ice, wind and rain play the role. In artificial weathering animals especially human beings interference causes soil erosion and formation.

7.1 Introduction

For maximization of yield of crops, it is essential to provide irrigation to crops. When either the natural sources like rainfall, dew, snowfall and other forms of precipitation or when the capillary rise of groundwater is not sufficient to meet the crop water demand, then there is need to supply irrigation. This irrigation water is a precious resource and need to be used cautiously. There are three important things need to be understood for optimum utilization of irrigation water with basic purpose to maximize the yield and returns. These three things are:

(i) When to irrigate?

(ii) How much to irrigate? and

(iii) How to irrigate?

In fact these three things form the core concept of irrigation scheduling.

8.1 Introduction

After knowing when to irrigate and how much to irrigate, next important thing is how to irrigate the crop field. Methods of irrigation play a very crucial role in deciding how to irrigate the crop fields since all the crops do not require same methods of irrigation. Depending on the sources of water available for irrigation, type of crop to be irrigated, quantity and quality of water to be applied and other economic considerations, methods of irrigation will vary. Irrigation water may be applied to the crops by flooding it on the field surfaces as surface irrigation, by applying it beneath the soil surface as subirrigation, by spraying it under pressure as sprinkler or overhead irrigation or by applying it in drops around the root zone of the crop as trickle irrigation. The commonly used methods of irrigation are described in schematic diagram as follows:

9.1 Introduction

In order to increase the production and productivity of crops, provision of irrigation system is highly essential. A project that makes use of weir or a barrage for providing irrigation to fields is called as direct irrigation system. On the other hand, a storage irrigation system makes use of storage reservoir by construction of dams. In order to provide irrigation by both the schemes, it is necessary to have a network of canal systems. A canal is an artificial channel, generally trapezoidal in shape constructed on the ground to carry water to the fields. The canal systems that provide water to the fields include main canals, branch canals, distributaries, minors and watercourses. It is imperative to design the canal systems properly for a certain realistic value of peak discharge that must pass through them so as to provide sufficient irrigation to the command areas. The flow irrigation that provides irrigation water to the fields may be of two types i.e. Inundation irrigation and Perennial irrigation.

10.1 Introduction

Irrigation is an age old practice. It has been practiced for thousands of years. It is chiefly used to irrigate rice in wetter areas; especially in Asian countries and dry land crops including vegetables and fruits in dry land areas having low rainfall in all most all countries. Devices for irrigation water lifting range from age old indigenous water lifts to highly efficient pump. Unlike canal irrigation where water is fed to the fields through gravity system, water from the surface and sub-surface sources is lifted either mechanically by pump or manually by any indigenous lifting devices. Irrigation by lifting water from a lower level to a higher level is called as lift irrigation. Several types of indigenous water lifting devices are in vogue in India since ancient times. These are animal or/and manually operated ones, the animal operated ones being more efficient than the manually operated ones. The earliest water lifts were simple man-powered devices, many of which are still being used with modifications in different forms. With gradual improvement, principles of simple machines, like the liver, pulley, screw etc. were employed in smooth lifting of water from surface and sub-surface sources. The selection of a suitable water lifting device for a particular situation depends on the following factors:

(i) Characteristics of source of water and the lifting device

(ii) Amount of water to be lifted

(iii) Depth of water table

(iv) Type and amount of power available and

(v) Economic status of the farmers.

11.1 Introduction

The entire amount of water that is diverted at the canal head regulator does not reach at the field for use of irrigation. Major amount of it is lost on way during its movement in the canal systems. During the passage of water from main canal to outlet at the head of the water course, water may be lost either by evaporation from the surface or by seepage through the peripheries of the channel. These losses are sometimes very high, and may go up to 50 % of the total water diverted into the main canal. Evaporation losses are low and may go to a maximum of about 7 percent.of total losses. The major loss of water in the conveyance system is the seepage loss. Seepage loss depends on the channel geometry and evaporation loss is proportional to the area of free surface. In determining the designed channel capacity, a provision of these water losses must be made. The provision for the water lost in the watercourses and in the field however, already made in the outlet discharge factor, and hence no extra provision is made on that account. However, excluding the above two losses, there is operational loss which when added to the evaporation and seepage losses, the total losses goes up the maximum 50 percent level. The operational loss includes spillage, over-toping, leakage through rodent holes, dead storage, initial infiltration and evapotranspiration from the vegetation along the watercourse. Evaporation and seepage losses of the canals are discussed below.

12.1 Introduction

Rainfall is the major source of water that contributes lion’s share for irrigation to crops. Before it reaches the earth, it is to a great extent pure in nature. By the time it falls on the ground surface, it comes in contact with various types of gases and suspended materials of the atmosphere and also after it flows as runoff on the surface it gets dissolved with many types of salts, impurities etc. that render the water to be impure. Many a time the industrial waste, agricultural wastes, pesticides, fungicides, chemical fertilizers etc. get mixed with water and make it unsuitable for irrigation use. Water being a universal solvent, it dissolves all most all organic impurities, salts etc. which makes it objectionable for both domestic and agricultural uses.

Irrigated agriculture is dependent on an adequate water supply of usable quality. In the past, water quality concerns were neglected because good quality water supplies were plentiful and readily available. This situation is now changing in many areas. Especially, in the arid and semi-arid zones, water quality is fast deteriorating which is posing threat to irrigated agriculture.

Conceptually, water quality refers to the characteristics of a water supply that will influence its suitability for a specific use. On the other hand, it refers to the situation of how well the quality meets the needs of the user. There are three quality indicators. They are physical, chemical and biological indicators. Even a personal preference such as taste is a simple evaluation of acceptability. For example, if two drinking waters of equally good quality are available, people may express a preference for one supply rather than the other; the better tasting water becomes the preferred supply. In irrigated agriculture, emphasis is placed on the chemical and physical indicators of the water and rarely the biological indicator is considered important.

13.1 Introduction

In agricultural lands, when the pores of the soil within the root zone of the crop get saturated with the subsoil water due to infiltration of high rainfall, excess irrigation or heavy seepage loss in the unlined canal systems, the air circulation within the soil pores get totally stopped. This phenomenon is called as waterlogging. In canal commands where there is continuous flow of water in the canals and canals are mostly unlined, there is heavy loss of seepage which raises the ground water table. This raising water table sometimes comes up to the ground surface which impedes surface drainage. By capillary action, under ground water rises to the crop root zone and submerges the roots of the crops for most of the time. This situation is called as waterlogging which creates salinisation and alkalinisation problems affecting the plant growth.

The height to which soil water rises above the water table by capillary action is called as capillary fringe. Generally, the height of the capillary fringe varies from 1 to 1.5 m. When the water table comes to 1.5 m below the surface of the soil, the land is said to be waterlogged. At times, due to poor drainage conditions, surface water cannot be freely drained out. The stagnate water in these low lying areas also causes waterlogging which enhances the weed growth consequently affecting the crop yield.

14.1 Introduction

Groundwater is an important source of water for irrigation. It is the most abundant fresh water resource of the earth. Underground water reservoirs contain large stock of fresh water resources. Total quantity of groundwater within 800 m distance below the ground surface is more than 30 times the total water in all fresh water lakes, more than 60 times the total water in soil and other unsaturated rock materials, more than 300 times the water vapour in the atmosphere and 3000 times the average volume of all rivers and rivulets in the world (Lenka, 2001). But the distribution of groundwater is not uniform. At some places, it lies below a few metres whereas at other places, it is a thousand metres or more below the ground surface. In some places, there is abundant groundwater potential whereas at other places there is meager potential.

Groundwater is the water reaching the groundwater reservoir from the infiltrated water of precipitation which constitutes an important component of the hydrologic cycle. It is only the part of the subterranean water that occurs in the saturated pores of the containing rock materials underlain by water held in a zone of aeration. It should not be confused that all the water present in soil below the ground surface is groundwater.

15.1 Introduction

The laws governing the flow of water in wells are referred to as the hydraulics of wells. Just like surface water flows from a higher elevation to a lower elevation by gravity, groundwater also flows from a region of higher water table to a region of lower water table. This difference of water table measured by any two piezometers divided by the longitudinal distance between them is called as hydraulic gradient. Hydraulic gradient plays a dominant role in deciding the flow of groundwater. This hydraulic gradient together with the hydraulic conductivity of the aquifer material forms the main law of well hydraulics called as Darcy’s law. An understanding of Darcy’s law together with some other laws as discussed subsequently in this chapter is essential in order to know the discharge of a well in a particular formation. Darcy’s law is valid for studying groundwater flow in alluvial formations. However, it is not valid for aquifers having hard rock areas.

16.1 Introduction

Producing more crops, livestock, fish and forest products per unit of water use is an essence of water productivity and is highly essential for both food and environmental security. A variety of options exist for improving the productivity of water in agriculture through breeding, better management practices and supporting policies and institutions. It is imperative to identify a range of means to enhance water productivity in agriculture, assess their potential and the consequences of their adoption. The production systems to be considered can vary from purely rainfed to irrigated, and from dry zones to semi-humid monsoonal areas.

The productivity of water used in agriculture has almost doubled during 1961 to 2001, It is mainly due to increases in crop yields. Irrigated rice yields doubled and rain-fed wheat yields rose by 160% in that period, with little variation in water consumption per kilo of output. Globally, FAO estimates that water needs for food per capita halved from about 6 m³/day to less than 3 m³/day during 1961 to 2001 which is a significant saving and an equally significant gain for other water users.

According to an estimate, a 1% increase in water productivity in food production enables to save about 24 lit/day of water per head of population, while a 10% increase would equal current domestic water consumption. Importance of saving water in agriculture can be realised from the above observation.

The application of machines to agricultural production has been one of the outstanding developments in world agriculture during last fifty years. The results of this development can be seen in many aspects such as reduction in burden and drudgery of farm work and worker, increase in production per worker, increase in cropping intensity due to timeliness of operations, reduction in grain losses and increase in farm employment. Mechanization is particularly advantageous when it can minimize a high peak labour demand that occurs over a relatively short period of time each year. For example, sowing of wheat and harvesting of paddy in the months of October and November, transplanting of paddy in the month of June and harvesting of wheat in the months of April and May. Severe labour shortages and high rate of wages during peak period, together with simultaneous demands for increased agricultural production had a marked influence on the mechanization of certain farm operations such as seedbed preparation, sowing/planting/transplanting, harvesting and threshing. Mechanization encourages better management of farms, improvement in working conditions and performance of jobs that would otherwise be difficult by hand. It also helps in reducing the cost of production.

Declining water table and degrading soil health are the major concerns for the current growth rate and sustainability of Indian Agriculture. Thus proper emphasis is being given on the management of irrigation water usage for adequate growth of agriculture. Keeping in view, the need for judicious use of our natural resources, concerted efforts are being made to enlighten the farmers for efficient use of irrigation water at farm level. Generally, in rice-wheat rotation farmers believed that their fields are levelled and needed no further levelling, but this is not true. Most of the fields are not adequately levelled and requires further precision land levelling. The enhancement of water use efficiency and farm productivity at field level is one of the best options to redress the problem of declining water level.

Levelling, smoothing and shaping the field surface is as important to the surface irrigation system and as the design of laterals, manifolds, risers and outlets for sprinkler drip irrigation systems. It is a process for ensuring that the depths and discharge variations over the field are relatively uniform and, as a result, that water distributions in the root zone are also uniform. These field operations are required nearly every cropping season, particularly where substantial cultivation following harvest disrupts the field surface. There are basically two types of land levelling viz. (i) to provide a slope which fits a water supply; and (ii) to level the field to its best possible condition with minimal earth movement. The second one is generally the most feasible one, because land levelling is expensive and large earth movements may leave significant areas of the field without fertile topsoil, and is the most economic approach also.

Tillage is a mechanical manipulation of soil to provide favourable condition for crop production. Soil tillage consists of breaking the compact surface of earth to a certain depth and to loosen the soil mass, so as to enable the roots of the crops to penetrate and spread into the soil. A good seedbed is generally considered to imply finer particles and greater firmness in the vicinity of seeds. The depth up to which tillage operations disturb the soil can classify the operation as shallow, medium or deep. The depth of tillage depends on the crop and soil characteristics and also on the source of power or energy available. The optimum seedbed preparation for raising upland crops, involves the many unit operations. Strength of soil is affected by soil moisture content and can be represented in terms of cone index. Compacted soil has more cone index than the loose soils. Movement of machine in the field causes soil compaction. Sometimes it forms hard pan which is to be broken by the tillage operations to enhance root growth and penetration and infiltration of excess water.

4.1 Seeding equipment

Sowing is an art of placing seeds in the soil to have good germination in the field and thereby gives better productivity. Seeding is one of the most important farm operations after soil preparation because the time of sowing and the way in which it is done decisively influence germination of the seed and growth of the seedling during its early stages. This in turn affects the subsequent time of weeding and inter-culture, harvesting and threshing and finally the yield. Seed needs an adequate supply of moisture, temperature, air and protected environment for good germination.

Crop sowing refers to broadcasting seeds on the surface of soil, placement of seeds in the soil or transplanting seedlings in the soil, under optimum conditions. The primary functions of any planting operation are to establish an optimum plant population and spacing, the ultimate goal being to obtain the maximum net return per unit area. Plant population and spacing requirements are affected by various factors such as the crop type and variety, soil type, soil fertility level, soil moisture and row spacing upon the cost and convenience of operations such as thinning, weed control etc. In order to get better returns, the right amount of seed should be placed at the right time and at a predetermined depth and spacing in the soil. Usually the depth of sowing depends upon the moisture availability and seed emergence capacity. The amount of seeds to be sown varies according to the size of seeds, percentage germination etc.

5.1 Weeding and Interculture Equipment

The aim of weeding and intercultivation operation is to provide best opportunity to crop to establish and grow vigorously up to time of maturity. The main objectives of weed control are to improve the soil conditions by reducing evaporation from the soil surface, improve infiltration of rain or surface water, and reduce runoff to maintain ridges or beds on which the crop is grown and to reduce competition of weeds for light, nutrients and water. Mechanical methods of weed control are simple and easily understood by farmers. The tools and implements for mechanical weed control are mostly manual and animal operated. Manual method is most effective but is slow. It is popular in regions where labour wages are low and labour is easily available during the season. The additional cost of weeding using implements is comparatively less than the gains due to extra yields obtained. First weeding operation is mostly done between and along the rows. Remaining operations are done mostly between the rows. Hand hoes are generally used for removing weeds between plants in a row.

Ever since man started domesticating plants and animals for food, feed and fiber, he is facing competition from insects, disease and other pests. The struggle is going to continue as long as man wants plants and animal. The need to save plants/crops from the ravages and depredations of pests and to reduce the losses caused by them became more urgent (Patel, 2004).

India is a predominantly agricultural country and will continue to be so. Neither individuals nor nations can live without agriculture. India is witnessing growth of its agriculture, industry and economy in general, at the same time the population is growing at an alarming pace.

The crop losses by pests in our country are enormous. Chemical control continues to play a major role in crop protection; at the same time it enhances the environmental pollution problem. One has to use chemical control in a precise way by adopting Integrated Pest Management (IPM). In applications of pesticide (which are poisonous), the technique used should be such that minimum quantity of pesticides is applied to cover the Target-Leaf-Foliage with less environment pollution. Water is usually used as a carrier to apply pesticides to the Target-Leaf-Foliage. Beside water, air stream is also used, to carry fine droplet-particles to reach the Target-Leaf-Foliage.

7.1 Harvesting and threshing equipment for cereal crops

Harvesting and threshing is an important operation in the farming. This can be done either manually or with the help of power operated machinery. Harvesting of field crops continues to be one of the most labour intensive operations in agricultural production system. Harvesting of crop is generally done by hand using sickle in India. Power operated harvesting machinery has not caught up with Indian farmers because of limited size of land holdings, economic constraints and non-uniformity of field conditions. Manual harvesting with different hand tools continues to be dominant, which takes 170-200 man-hours to harvest one hectare of paddy crop. Due to high labour demand at the time of harvesting, the operation continues for weeks together, resulting in over drying of crops in the field causes grain losses to the extent of 5 to 15 percent and even results in loss of crop due to untimely rain during harvesting. Mechanical devices to harvest wheat and paddy crops have become popular especially in northern India to minimize the field losses resulting from shattering, unfavourable weather conditions and pilferage.

Forage harvesting is more complex as compared to grain crops. Forage crop is of great bulk and mass, containing 70-80% water when first harvested. For storage it must be dried, either naturally or artificially, to a safe moisture content of about 20 to 25%. Due to low product value it limits the economic feasibility of mechanization of harvesting operation. The mowers are used to cut the crop and windrow in the field, which is manually collected for further chopping. The forage harvester consists of a combination of plant-cutting unit and a chopping unit and is called field forage harvester. The field forage harvester performs the functions of both row binder and silage cutter, as it severs the standing stalks from the ground and chops them into silage in one continuous operation in the field. It can be grouped into two according to the mechanism used to cut the crop viz. field choppers and flail harvesters.

9.1 Farm Tools and Equipment for Horticulture and Plantation Crops

Agriculture in India is one of the most prominent sectors in its economy. Agriculture and allied sectors like forestry, logging and fishing accounts for about 14% of the GDP and employed 60% of the country’s population. About 43% of India’s geographical area is used for agricultural activity. Despite a steady decline of its share in the GDP, agriculture is still the largest economic sector and plays a significant role in the overall socioeconomic development of India. Nearly 80 percent of the farm population operates smallholdings, the average size of holding being 1.16 ha. Out of a total geographical area of 329 m ha, about 142 m ha constitute the net sown area. Nearly 63 percent of this area is rainfed and its contribution to the overall production is 44%.

Indian agriculture is predominantly a rainfed agriculture under which both dry farming and dry land agriculture is included. Dry farming was the earlier concept for which amount of rainfall (less than 500 mm annually) remained the deciding factor for more than 50 years. In modern concept, dry land areas are those where the balance of moisture is always on the deficit side. In other words, annual evapo-transpiration exceeds precipitation. In dry land agriculture, there is no consideration of amount of rainfall. It may appear quiet strange to a layman that even those areas which receive 1100 mm or more rainfall annually fall in the category of dry land agriculture under this concept. The success of crop production in these areas depends on the amount and distribution of rainfall, as these influences the stored soil moisture and moisture used by crops. The amount of water used by the crop and stored in the soil is governed by the water balance equation: ET = P-(R+S). When the balance of the equation shifts towards right, precipitation (P) is higher than ET, so that there may be water logging or it may even lead to run off (R) and flooding (S). On the other hand, if the balance shifts to the left, ET becomes higher then the precipitation, resulting in drought in the various severity. Taking the country as a whole, as per meteorological report, severe drought in large area is experienced once in 50 years and partial drought in five years while floods are expected every year in one part of the country or the other, especially during rainy season. In fact the balance of the equation is controlled by the weather, season, crops and cropping pattern. Out of 142 million ha of net sown area in the country, rainfed agriculture is practiced in 95 million ha (67%). Nearly 67 m ha of rainfed area falls in the mean annual precipitation range of 500-1500 mm.

There are many environmental risks associated with stubble burning. Thus the adoption of alternative straw management strategies is the best interest of all concerned. Key points when considering harvesting surplus cereal straw are: i) maintain sufficient crop residue on the land to protect the soil from erosion. This can be accomplished by keeping the stubble standing particularly after seeding; ii) harvest surplus crop residue with an appropriate frequency so as not to lower soil organic matter, soil fertility and crop productivity; and iii) fertilize crops according to soil test recommendations. The decision regarding the amount of straw to be removed should be based on the inherent value of the straw for maintaining the viability of the cropping system and protecting the soil resource versus the value of the straw for other uses (e.g., feed and bedding for livestock, industrial strawboard and feedstock for alternative energy forms). The value of retaining the straw on the land is difficult to determine but should be based on a number of factors such as: value of straw for soil erosion control; equivalent fertilizer value of the nutrients contained within the straw; value of the straw for building soil organic matter, soil quality, and soil tilth; and value of the straw for soil moisture conservation (Singh et al., 2003; Singh et al., 2009). At harvest, it is best to chop the straw as fine as possible and spread both the straw and chaff across in the field. A number of equipment have been developed for managing the straw in the field and discussed here.

Introduction

Modern intensive livestock and poultry production has achieved phenomenal gains in the efficient and economical production of high quality and safe animal products and by-products. Furthermore, the overall performance of livestock can be increased by improving nutrients utilization, health status, fertility and efficiency of production. The use of feed additives has been an important part of achieving efficient livestock production. Feed additives are non-nutritive substances, preparations and micro-organisms that are added to animal feed to improve productive, reproductive and health performances. Any substance is considered as a feed additive when, not having a direct utilization as nutrient, is included at an optimum concentration in diet to exert a positive action over the animal health status or the dietary nutrient utilization. Hutjens (1991) defined feed additives as a group of substances that can cause a desired animal response in a non-nutrient role, such as pH shift, growth, or metabolic modifier. Feed additives are added deliberately to animal feed which may favourably influences characteristics of the animal feed, feed intake, gastro-intestinal flora, digestibility of the animal feeds, animal production, health, fertility and characteristics of animal products. Because of their chemical nature as active principles, additives are generally included in very small proportions in diet.

Introduction

The competition between human and livestock population for the existing animal and plant resources has been of great concern to the poultry nutritionists. Today the poultry industry has already challenged by the high price of the feed ingredients. Moreover in the next century there will be a shortage of conventional feed stuffs for use in poultry production. Efforts are on to look forward for the new feed resources and to evaluate them for their inclusion in the poultry ration. However many of the feed stuffs are characterized by the presence of certain incriminating factors. The incorporation of feed stuffs containing incriminating factors may adversely affect the performance of poultry. The nutritional strategy involving the use of feed enzymes offer immense potential to overcome the problems. The use of enzymes in feed mixtures of growing poultry particularly for young chicks has been the subject of much research activity in the recent decades. The interest in the feed enzymes is a reflection in changing the attitude of the society and the economic climate of the feed industry. It has been seen that approximately 187 million metric tons of cereal grains (FAO, 2011) and 26.02 million tons oil seeds as per the trade estimate for 2011-12 are produced in India which yield non starch polysaccharides (NSP) as a part of variety of products.

Introduction

During the intensive system of poultry production birds are exposed to several types of stresses. The birds can tolerate mild stress but when the stress is severe, there is imbalance between oxidants and antioxidants which lead to oxidative stress and lipid peroxidative damage of tissues, ultimately results in poor performance. Nutrition has a strong impact on oxidative stress. Insufficient intake of antioxidants, a high intake of prooxidants, or both may lead to oxidative stress. The detrimental effects of oxidation process can be prevented by addition of antioxidant compounds in the feed. Vitamin E, carotenoids and selenium (Se) are among important antioxidant components of poultry diets. It is important to understand the role of antioxidants in poultry nutrition in general and in production and reproduction in particular. The chapter, here in will discuss the stressors in poultry production, oxidative stress and possible alleviation through dietary antioxidant supplementation.

Pankaj Kumar Singh and Chandramoni

Introduction

The term “probiotic” is derived from Greek and means pro: for and bios: life (for life) in contradiction to antibiotic which means: against life. The term probiotic was first introduced by Lilly and Stillwel (1965) to describe growth-promoting factors produced by microorganisms. Parker (1974) first specified designation “probiotic”. He defined probiotics as microorganisms or substances, which contribute to the balance of the intestinal micro flora. Crawford (1979) defined probiotics as a culture of specific living microorganisms, primarily Lactobacillus spp. that are implanted in the organism and ensure the rapid and effective establishment of a beneficial intestinal population. Fuller (1989) discussed the definition given by Parker (1974) and considered it too broad, as cultures, cells, and metabolites are also included in antibiotic preparations. He redefined “probiotic” as a live microbial feed additive, which beneficially affects the animal by improving its microbial balance. Havenaar et al. (1992) pointed out that the definition of “probiotic” made by Fuller (1989) was restricted to feed supplements, animals, and their intestinal tract. Therefore, they generalized Fuller’s definition of “probiotic” as a mono or mixed culture of living microorganisms, which beneficially affect the host by improving the properties of the indigenous micro-flora. Through 1989, United States Department of Agriculture (USDA) advised manufactures to use the term: “direct-fed microbial” (DFM) instead of “probiotic” (Miles and Bootwalla, 1991). The USFDA defined DFM as a source of live naturally occurring microorganisms, including bacteria, fungi, and yeast. Vanbelle et al. (1990) pointed out that most researchers considered “probiotic” for selected and concentrated viable counts of lactic acid bacteria. Koh et al. (1992) pointed out that as a biological product for newly hatched chicks a bacterial culture producing acetic acid could be used. Such a culture might be supplied to the chicks either through their drinking water or by the feed. For controlling the biological balance in the chicken’s intestinal tract different probiotics may be used. The US National Food Ingredient Association presented, probiotics (direct fed microbial) as a source of live naturally occurring microorganisms and this includes bacteria, fungi and yeast (Miles and Bootwalla, 1991). According to the currently adopted definition by FAO, probiotics are: “live microorganisms which when administered in adequate amounts confer a health benefit on the host” (FAO/WHO, 2001). More precisely, probiotics are live microorganisms of nonpathogenic and nontoxic in nature, which when administered through the digestive route, are favorable to the host’s health (Guillot, et al., 1998; Thomke and Elwinger, 1998,).

Introduction

Prebiotics are non-digestible food ingredient which beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of health-promoting bacteria in the intestinal tract, thus improving the host‘s microbial balance (Gibson and Roberfroid, 1995). Normally, prebiotics contain some type of a non-digestible carbohydrate fraction (Rehman et al., 2009). Almost 90% of oligosaccharides escape digestion in the small intestine and reach the colon where they selectively stimulate the growth and/or activity of beneficial bacteria like Bifidobacteria, Lactobacillus and Streptococcus, providing prebiotic properties (Stanton et al., 2003). These bacteria populate the gut filling any niches were pathogenic bacteria may attempt to take hold. This concept is better known as competitive exclusion. Prebiotics function by lowering the gut pH through lactic acid production, inhibiting/preventing colonization of pathogens, modifying metabolic activity of normal intestinal flora, and stimulation of the immune system (Doyle and Erickson, 2006). Studies have demonstrated that these bacteria reduce pathogenic bacteria like Salmonella spp., Clostridium diffile and Campylobacter spp. (Hopkins and Macfarlane, 2003; Stern et al. 2000), by diverse mechanisms including competitive exclusion of nutrients or adhesion sites to intestinal mucosa (Stern et al. 2000) and fatty acid of short chain production, like propionic and butyric acids, which modifies the acidic conditions and inhibits the growth of microorganisms that cause infections (Collins and Gibson, 1999).

Introduction

Synbiotics refer to nutritional supplements combining probiotics and prebiotics in form of a synergism. The synbiotic concept was first introduced as “mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of health-promoting bacteria. Probiotics are live bacteria which are intended to colonize the large intestine and confer physiological health benefits to the host. A prebiotic is a food or dietary supplement product that enhances the activity of probiotics. Synbiotics are not drugs and the effects are due to changes in bacteria population or enhancement of activity of the bacteria. A synbiotic may contain fiber, but all fiber is not necessarily a synbiotic.

Using prebiotics and probiotics in combination is often described as synbiotic, but the United Nations Food & Agriculture Organization (FAO) recommends that the term “synbiotic” be used only if the net health benefit is synergistic. A synbiotic contains fiber such as fructose oligosaccharide, galactose oligosaccharide, etc. and is intended to stimulate the microflora in the large intestine. The combination of probiotics and prebiotics work separately in the small and large intestine, but synergistically increase the overall gut health. Prebiotic has shown to increase the population and/or function of the probiotic it is paired with, as the probiotic is an external species, whereas prebiotics stimulate the flora which is already present.

Introduction

With the perception that antibiotics should no longer be used as animal growth promoters, there has been widespread interest in natural methods of inhibiting detrimental bacteria. Their removal from the poultry diets is therefore brings with it consequences. This has lead to somewhat of a renaissance in research activity on the discovery and application of non antibiotic chemical compounds capable of either killing microorganisms outright or at the very least retarding growth sufficiently to limit their dissemination. Organic acids have a long history of being utilized as food additives and preservatives for preventing food deterioration and extending the shelf life of perishable food ingredients. In recent past organic acids have been used to control microbial contamination and replace antibiotic growth promoters in poultry (Ricke, 2003; Hassan et al.,2010; Adil et al., 2011).

Introduction

After the discovery that low concentrations of antibiotics included in livestock diets had a beneficial effect on production efficiency, the use of antibiotic growth promoters (AGPs) became a common practice, benefiting both the livestock industry and consumers. Antibiotic growth promotion in agricultural and animal production has been practiced for about 50 years (Dibner et al., 2007). Orally ingested antibiotics promote growth and efficiency of poultry and other animals. Early indications of a beneficial effect on production efficiency in poultry and swine were reported by Moore et al. (1946) and Jukes et al. (1950).

Introduction

An ionophore is a lipid-soluble molecule usually synthesized by microorganisms, which transport ions across cell membranes of susceptible bacteria, dissipating ion gradients and uncoupling energy expenditures from growth to kill these bacteria. The term ionophore was first used in 1967 for their ability of organic molecules to bind metal cations and form lipid soluble complexes that facilitate their transport across cell membrane. The ionophore antibiotics show wide varieties of biological activity ranging from antibacterial, antifungal, antimycoplasma, antiparasitic, antimalarial, antiviral, anti-inflammatory and tumourcell cytotoxic activity (Augustine, et al., 1987; Gumila et al., 1996). Presently seven polyether antibiotics include monensin, lasalocid, salinomycin, narasin, maduramycin, laidomycin and senduramycin are used around the world in various segments of cattle and poultry industries. These ionophores are mainly used as anticoccidial drugs in poultry and growth promoters in the ruminants. Polyether antibiotics are not used in human but recently, it has been shown that some of these compounds are able to selectively kill human cancer stem cells and multidrug resistant cancer cells. Hence, they are recognized as new potential anticancer drugs.

Introduction

To improve the growth and health status, addition of antibiotics in the poultry feed was a common practice in last decade. Currently, in developed countries it is banned due to fatal consequences like development of antimicrobial resistant organism pool in the gut, persistence of antibiotic residue in the food chain that can reduce the food safety level. Therefore, various alternatives are now a day thought to use as poultry feed additives. Immunomodulaors are presently receiving wide attention as feed additives.

The term ‘immunomodulation’ is generally used to describe the manipulation of immune system which consists either increase (immunostimulation) or decrease (immunosuppression) in the magnitude of the immune system function. The chemicals or biological substances producing this phenomenon are known as ‘immunomodulators’. Specific immunomodulation involves the change in the immune response with a particular antigen (e.g. vaccination). Whereas, non-specific immunomodulation alters the immune response in such a way so that it become sensitive to a wide range of antigens. Generally this kind of non-specific immunomodulators are used as poultry feed additive to increase the resistance against the wide range of infections. The principal components of the immune system targeted for immunomodulation include T cells, B cells, monocytes, macrophages, granulocytes and natural killer cells (Dalloul and Lillehoj, 2005).

Introduction

There is concern that antibiotic-resistance in bacteria may make commonly used antibiotics less effective. Oral immunotherapy (passive immunization) with specific antibodies is a strategy that has been actively pursued in laboratory and clinical studies for the last two decades. Feeding of egg yolk antibodies to neutralize specific pathogens, especially enteric microorganisms, is a potential alternative to antibiotics. Oral administration of these antibodies has met with some degree of success in prevention of viral and bacterial enteric infections in humans, piglets, calves, fish and rabbits. It is proposed that the egg yolk antibodies may act against enteric pathogens by binding, immobilising and consequently reducing or inhibiting the growth, replication, or colony forming abilities of these pathogens. Three immunoglobulin classes (IgA, IgM and IgY) have been shown to exist in chickens. Chicken immunoglobulin G (IgG) has been designated as immunoglobulin Y(IgY) because it varies in several aspects from mammalian IgG. IgY is the main serum immunoglobulin in chickens. It is transported from the hen to the embryo via the egg yolk. The egg yolk thus contains high concentrations of IgY. Other immunoglobulin (Ig) classes are present only in negligible amounts in the egg yolk. It has been shown that the presence of immunoglobulins in eggs is an example of passive immunity. This is because these antibodies originated from the hen and are used to protect the offspring from various infectious diseases after hatch.

Introduction

Coccidiosis is the most economically harmful disease encountered in commercial poultry production. It is caused by single celled protozoan parasites of the genus Eimeria which are commonly referred to as coccidia. Williams (1998) reported that the annual worldwide loss is about $ 800 million. The total loss due to coccidiosis is found to be Rs. 1.14 billion in India. The important finding is that almost 70 percent of the estimated cost is due to subclinical coccidiosis, by impact on weight gain and feed conversion rate. One of the reasons for these remarkable finding is probably the difficult diagnosis of subclinical coccidiosis.

Chickens are susceptible to at least seven species of Eimeria. The most common species are Eimeria tenella, which causes the caecal coccidiosis, E. necatrix &E. maxima, which causes mid intestinal coccidiosis, E. acervulina which causes anterior intestinal coccidiosis and E. brunetti which causes posterior intestinal or rectal coccidiosis. E. mitis and E. praecox are generally mildly pathogenic and commonly occurring as co-infection/mixed infection in with other species. Coccidiosis is particularly difficult to combat because several different species of Eimeria exist in the field. Poultry may become infected with different species because the immunity that develops after infection is specific only to one species. Eimeria has direct and complex life cycle that involves many developmental stages within the host cells. Each Eimeria species has characteristic intestinal lesions and type of diarrhoea (with or without blood).

Introduction

For the past few decades, a number of chemical feed additives such as antibiotics, ionophores, methane inhibitors and defaunating agents have been introduced into ruminant nutrition in order to improve rumen fermentation, and increase growth and milk production by improving intake and feed conversion efficiency. However, most of these supplements are not used routinely because of toxicity problems to the host animals and microbial adaptation to these additives. Most importantly, growing awareness from public health aspects has centered on the safety of tissue residues of these chemicals and also bacterial resistance to antibiotics as a result of increased use in the food chain. These supplements have been criticized by the consumers’ organizations on the ground of product safety and quality. Antibiotic feed additives are banned in European Union. The consumers’ demands have drived the search for natural alternatives to chemical feed additives for eco-friendly animal production. Plants are part of herbivore diets, and these plants contain bioactive compounds with antimicrobial properties can be of interest in animal nutrition. Therefore, recent research has been greatly focused to exploit bioactive plant secondary compounds as natural feed additives to improve rumen fermentation such as enhancing protein metabolism, decreasing methane production, reducing nutritional stress like bloat, and improving animal health and productivity (Wallace et al., 2002; Patra and Saxena, 2009a, b; 2010; 2011), which may be useful in eco-friendly livestock farming (Patra, 2007). This review discusses the effects of different plant metabolites on rumen fermentation, rumen microbial ecosystems and ruminant performance.

Introduction

There is growing worldwide interest in reducing methane emissions from domestic ruminants. Methane is a potent greenhouse gas and its release into the atmosphere is directly linked with animal agriculture, particularly ruminant production. Methane emitted from ruminant livestock is regarded as a loss of feed energy and also a contributor to global warming. Methane is synthesized in the rumen as one of the hydrogen sink products that are unavoidable for efficient succession of anaerobic microbial fermentation. Various attempts have been made to reduce methane emission, mainly through rumen microbial manipulation, by the use of agents including chemicals, antibiotics and natural products such as oils, fatty acids and plant extracts. A newer approach is the development of vaccines against methanogenic bacteria. While ionophore antibiotics have been widely used due to their efficacy and affordable prices, the use of alternative natural materials is becoming more attractive due to health concerns regarding antibiotics. An important feature of a natural material that constitutes a possible alternative methane inhibitor is that the material does not reduce feed intake or digestibility but does enhance propionate that is the major hydrogen sink alternative to methane. Since methane contains energy, its emission during rumen fermentation is considered to be a loss of feed energy that is equivalent to 2-12% of the gross energy of animal feed (Johnson and Johnson, 1995). Some implications of these approaches, as well as an introduction to antibiotic-alternative natural materials and novel approaches, are provided.

Introduction

Ruminants are provided with a microbial ecosystem in the gastro-intestinal tract which helps in the bioconversion of lignocellulosic feeds into volatile fatty acids which are utilized by the animal as a source of energy. This microbial biomass is also helpful in synthesis of microbial protein and B-complex vitamins for the host animals. Any disturbance in the microbial balance may affect the performance of the animal adversely and any improvement in the microbial environment may lead to the improvement in productivity of the animal. A number of chemical feed additive like hormone, antibiotics have been used to improve the performance of the animals. But due to residual left over in the animal products and risk of creating disease, resistance against antibiotics, the use of these chemical feed additives have been discouraged and even banned in some countries. As an alternative microbial feed additive seems to be more natural; as it is not creating any new thing in GIT but it is merely restoring the normal and ideal flora in the digestive tract to its full capacity.