eChapters

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.

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.

Introduction

The original concept of feeding bacterial direct fed microbial (DFM) to livestock was based primarily on potential post–ruminal effects, including improved establishment of beneficial gut microflora (Fuller, 1999). Calves fed Lactobacillus acidophilus have been reported to have reduced incidence of diarrhoea (Beecham et al., 1977) and reduced intestinal coli form count (Bruce et al., 1979). But now it is known that certain bacterial DFM also have beneficial effects in the rumen and one of the important groups of this type of bacteria is propionic acid producing bacteria (Elsden, 1945; Johns, 1951a; Langa, 2010). This group of bacteria includes Propionibacterium spp., Veillonella spp., Megasphaera spp., Selenomonas spp. and Succiniclasticum spp. (Table 1). Propionic acid producing bacteria (PAPB) are secondary bacteria which enhance propionate production by utilizing the end products of primary fibrolytic or starch utilizing bacteria which produce succinic acid and lactic acid (Swenson and Reece, 1996). Inoculation of in vitro fermentation with the lactate utilizing ruminal bacterium Megasphaera elsdenii prevented lactate accumulation and produced propionic acid when a highly fermentable substrate was used (Kung and Hession, 1995). Propionibacteria are also rumen active bacteria which can produce propionic acid by utilizing glucose, lactic acid and succinic acid (Elsden, 1945; Grinstead and Barefoot, 1992; Hugenholtz et al., 2002). Ghorbani et al. (2002) also reported that Propionibacteria convert lactate and glucose to acetate, propionate and CO₂. They also reduce nitrate to nitrite and reduce nitrite load by 40-60% and minimize changes in blood nitrite and met hemoglobin (Rehberger et al., 1993). Succinic acid is an important end–product, but in practice this is converted into propionic acid by other bacteria such as Selenomonas ruminantium (Swenson and Reece, 1996; McDonald et al., 2002; Langa, 2010); such interactions between microorganisms are an important feature of rumen fermentation. Veillonella gazogenes are also active in the rumen and produce propionic acid by fermenting succinic acid (Johns, 1951a). Moreover in low quality forage-based diet Fibrobacter succinogenes are predominant fibrolytic bacteria which digest fibre faster and produce sufficient amounts of succinic acid in the rumen (Cheng et al., 1984; Miron and Ben-Ghedalia., 1992) and synergistic increases in propionate production and fiber digestion was found in co-cultures of Fibrobacter succinogenes and Selenomonas ruminantium (Sawanon et al,2003), and of Ruminococcus flavefaciens and Selenomonas ruminantium (Sawanon et al., 2006). These findings suggest that positive interactions occur between bacteria, mostly via metabolite exchange.

Introduction

The process of making the rumen of animals free of rumen protozoa is called defaunation and the animal is called defaunated animal. The role of rumen ciliate protozoa on the performance of host animals became debatable issue when Becker and Everett (1930) demonstrated that rumen protozoa were non-essential for growth in lambs. Nevertheless, the reports of recent years reflect that though protozoa may be non essential for ruminant, still they have significant role to play in the rumen metabolism specially to stabilize the rumen pH (Santra and Karim, 2002a). Rumen protozoa are the largest in size among rumen microbes and contribute 40-50% of the total microbial biomass and enzyme activities in the rumen (Agarwal et al., 1991).

Introduction

Enzymes are globular proteins that act as biological catalysts. They are produced by living cells to bring about specific biochemical reactions. Digestive enzymes catalyze the degradative reactions by which substrates (i.e., feedstuffs) are digested into their chemical components (e.g., simple sugars, amino acids, fatty acids) which in turn, are used for different body functions. Different enzymes are utilized for the complete digestion of complex feed. The enzymes are being used in the feeding industry from last several decades. Various digestive enzymes have been studied for use as feed additives to enhance animal performance They are commonly used to improve the nutritive value of feeds for non-ruminants (especially, poultry and swine). They are not routinely used in adult ruminant diets because the fibrolytic activity within the rumen environment is normally very high, and it is assumed that exogenous enzymes cannot survive proteolysis in the rumen (Kopency et al., 1987). Forages are the main feed component that serve as the major source of energy available to the animal in ruminant production system. However, due to slow or incomplete digestion of fibrous substrates only 10 to 35% of energy intake is available as net energy that significantly limits livestock performance and profits in production systems. To improve the ruminal fibre degradability many strategies have been developed to stimulate the digestion of the fibrous components in ruminant feeds. That includes, use of various feed additives which stimulates fiber digestion, physical and chemical processing of feeds in order to enhance the rate and extent of fiber digestion. However, the use of “natural” product to enhance production efficiency is highly recommended that can potentially play some role in replacing performance benefits vacated by antibiotics and hormones. Enzymes are proteins that are ultimately digested or excreted by the animal, leaving no residues in products, which was a major drawback in the use of antibiotics and hormones.

Introduction

While world population is expected to increase from 6 billion to about 8.3 billion, India is likely to be the most populous nation with 1.6 billion in the year 2030. Therefore, it is essential to be prepared to produce sufficient food for the increased population with the application of newer technologies. The consumption of animal food was 10 kg/yr in the 1960s increasing to 26 kg/yr in 2000 and is expected to be 37 kg/yr by 2030 (FAO, 2008; 2009). Large increases in per capita and total demand for meat, milk and eggs are forecast for most developing countries for the next few decades (Delgado et al., 1999). In developed countries, per capita intakes are forecast to change slightly, but the increases in developing countries, with their larger populations and more rapid population growth rates, will generate a very large increase in global demand.

Moreover, an increasing number of consumers demanding healthy and quality foods have pushed researchers into development of technologies that can control the proportion of lean and fat muscle deposition in meat producing animals. A number of technologies have been developed that led to remarkable improvements in the efficiency of animal production and in carcass composition and meat quality. There are some dietary additives and vitamins that may increase protein and muscle deposition, while often simultaneously reducing fat deposition by modifying nutrient metabolism in individuals.

Introduction

For raising animal and its products especially protein, food and nutrition plays an important role. Feed cost comprises about 60% of total recurring expenditure. Feed additives play an increasingly important role in animal nutrition by augmenting the performance by maintaining the needs of essential nutrients, improving feed conversion therefore optimize feed utilization (Wenk, 2000). Feed additives are a group of feed ingredients that can cause a desired animal response in a non-nutrient role, such as rumen modifier, growth or metabolic modifier (Hutjens, 1991). These are used in micro quantities and require careful handling and mixing. The development and introduction of various new feed additives is a major and practical solution to improve the efficiency of animal production, to alleviate environmental pollution, to maintain animal health, welfare and to ensure the safe and of good quality food production.

Introduction

Growth enhancement technologies have been widely embraced in the livestock industry to improve growth, efficiency and carcass traits. For over 50 years, estrogenic and androgenic hormone implants were widely used in the cattle feeding industry, and it is estimated that approximately 97 percent of feedlot cattle in the U.S. receive one or more implants during the finishing phase (Barham et al., 2003; Tatum, 2006). There is a large body of literature that indicates the positive growth enhancement effects which implants impart on growing and finishing cattle and producers have extensively used implants to increase live body weight, improve average daily gain and feed efficiency, and reduce the number of days cattle are on feed (Apple et al., 1991; Duckett et al., 1997;Milton and Horton, 1996; Perry et al., 1991). Likewise, there is a growing body of literature that indicates the positive response on growth and carcass characteristics that finishing cattle have to beta-adrenergic agonists. The hog industry, and more recently, the cattle feeding industry have increased utilization of beta-adrenergic agonists to improve the efficiency of production. While the use of Ractopamine hydrochloride (Paylean^®, Elanco Animal Health, Greenfield, Indiana) has been used extensively in hog production since its approval by the Food and Drug Administration (FDA) in 1999, similar pharmaceutical feed additives have only recently been implemented in commercial cattle feeding operations. Beta-adrenergic agonist use in fed cattle has substantially increased following the FDA approval of Ractopamine hydrochloride (Optaflexx^®, Elanco Animal Health, Greenfield, Indiana) in 2003, and the approval of Zilpaterol hydrochloride (Zilmax^®, Merck Animal Health, Summit, New Jersey) in 2006. The use of both Ractopamine hydrochloride (RH) and Zilpaterol hydrochloride (ZH) have shown to elicit similar improvements in live weight gain, average daily gain, and feed efficiency as those reported in hormone implants (Allen et al., 2009; Avendano-Reyes et al., 2006; Beckett et al., 2009; Elam et al., 2009; Gruber et al., 2007; Kellermeier et al., 2009; Scramlin et al., 2010). In addition, these compounds have been reported to have profound effects on hot carcass weight, Longissimus muscle area and carcass cutability (Gruber et al., 2007; Hilton et al., 2010; Rathmann et al., 2009; Scramlin et al., 2010; Shook et al., 2009; Vogel et al., 2009). It is because of this that cattle feeders have drastically increased use of beta-agonists since their FDA approval, and a growing portion of the fed cattle population receive a dietary beta-agonist supplement that is provided within the final 20 to 30 days of finishing.

Introduction

Supplementary feeding is an essential practice in fish farming operation which accounts for over 60% in total input cost. The dependence of candidate species on balanced supplementary feed increases with increase in stocking population in ponds targeting per hectare higher production as the standing crop of cultured species exceeds the natural feeding capacity of ponds. Therefore, feeding of artificial feed balanced in all nutrients such as protein, lipid, carbohydrate, vitamins and minerals containing optimum protein and energy ratio has assumed foremost importance in aquaculture industry. The use of balanced feed however, is directed towards optimum realization of genetic potentials of farmed species for survival, immunity, growth and reproduction (Mohanty, 2009). Consequent to researches done in India and abroad, a strong data base has been developed about the nutritional behavior of great majority of these cultivable fish and shell fish species and several feed formulations have been successfully undertaken. With optimum pond management, feeding of formulated balanced feed, it has been possible to increase aquaculture production as high as 15- 17 t/ha/yr for carps and 8-12 t/ha/yr in semi intensive prawn and shrimp farming in India (Mohanty, 2009).

Introduction

Public concern over use of antibiotics in livestock production has increased in recent years because of their possible contribution to emergence of antibiotic resistant bacteria, and their transmission from livestock to humans. Accordingly, ruminant microbiologists and nutritionists have been exploring alternative methods of favorably altering ruminal metabolism to improve feed efficiency and animal productivity. Plant extracts contain secondary metabolites, such as essential oils (EO) that have antimicrobial properties that make them potential alternatives to antibiotics to manipulate microbial activity in the rumen. Essential oils are naturally occurring volatile components responsible for giving plants and spices their characteristic essence and color. Over the last few years, a number of studies have examined effects of EO, and their active components, on rumen microbial fermentation. However, many of these studies are laboratory based (i.e., in vitro) and of a short-term nature. Nevertheless, results from in vitro batch culture studies provide evidence that EO and their components have the potential to improve N and/or energy utilization in ruminants. Effects of EO on ruminal N metabolism is more likely mediated by their impact on hyper-ammonia producing (HAP) bacteria resulting in reduced deamination of amino acids (AA) and production of ammonia N.

Introduction

Plant products have been used for centuries by humans as food and to treat ailments. Natural medicinal products originating from herbs and spices have also been used as feed additives for farm animals in ancient cultures for the same length of time. Keeping farm animals healthy is necessary to obtain healthy animal products. The main scope in animal husbandry is to ensure good performance of farm animals and get quality animal products, which can be achieved only with the effort to keep the animals healthy. Only quality feed together with proper hygiene, potable water and management can ensure the production of nutritious animal products with desired organoleptic properties (Saxena, 2008). A ban of antibiotics as feed additives in animal nutrition is realized since 1986 in Sweden and later on to various countries. A general ban is foreseen in some years from now, because of the increased occurrence of pathogens resistant against therapeutical antibiotics used in animals and humans. With the restricted use or ban of dietary antimicrobial agents we must explore new ways to improve and protect the health status of farm animals, to guarantee animal performance and to increase nutrient availability (Wenk, 2003). In this aspect, herbs and spices are not just appetite and digestion stimulants, but can, with impact on other physiological functions, help to ensure good health and welfare of the animals, what can positively affect their performance.

Introduction

Mycotoxins are substances produced by fungal infections which in some cases do protect plants or plant seeds against parasites (Schardl et al., 1996). However, upon ingestion, inhalation or dermal contact, these mold producing substances are poisonous to vertebrates. Even with more than 100,000 species of fungi known, only some of them are active mycotoxin producers. The fungi species which are known to produce the most hazardous mycotoxins in agriculture and in animal production are Fusarium, Aspergillus and Pencillium spp. Mycotoxins vary greatly regarding their toxicological effects as they do not belong to a single class of chemical compounds (Jewers, 1987). The environmental conditions in which they are preferably produced also differ. Fusarium toxins, such as trichothecenes, Zearalenone and fumonisins are commonly produced on the field, whereas aflatoxins and ochratoxins are produced by Aspergillus and Penicillium spp. mainly after harvest and during poor storage conditions.

Introduction

Plant pests have been a part of the man’s environment, since ages. Traditional agriculture which included diverse crops and indigenous crop management practices provided little opportunity for the pests to build up and spread rapidly (Smith and Allen,1954). Crop production is constantly threatened by increasing difficulties in controlling insect pests, which are a major impediment to improved livelihoods of the poor farmers. However, in the quest for increasing food production for the growing population, use of pesticides became a norm in crop management. Pesticides became an integral part of the process owing to losses from weeds, diseases and pests reducing the harvestable produce. Use of pesticides along with high yielding varieties, irrigation and improved seed did result in increased productivity. But the rampant use of these chemicals, under the adage, “if little is good, a lot more will be better” has played havoc with human and other life forms.

Introduction

Integrated Pest Management (IPM) has evolved over the last five decades since Stern et al. (1959) first gave the concept of integrated control. The basic tactics of IPM were developed and applied to reduce crop losses against the ravages of pests before the term IPM was coined (Jones, 1973; Smith et al.,1973). Entomologist at the university of California, United State of America (USA) played a pivotal role in developing IPM tactics (Perkins, 1982). Development of resistance to insecticides and the elimination of natural enemies by insecticides led to the development of ‘supervised control’. The publication of the book ‘Silent Spring’ written by Rachel Carson (1962) was a defining milestone for it brought the problems caused by pesticides to the attention of the public and the scientists. The term ‘integrated pest management’ was used for the first time by Smith and van dan Bosch (1967). In the last five decade many synthetic pesticides have been banned. In 1972, ’integrated pest management’ and its synonym were incorporated into English dictionary and accepted by the scientific community (Kogan, 1998). IPM is the main strategy accepted for pest management under agenda 21 of the United Nations conference on Environment and Development (UNCED, 1992).

Agriculture has always played and will continue to play a dominant role in the growth of Indian economy in the foreseeable future. It represents the largest sector producing around 28 per cent of the gross domestic product (GDP). Achieving self sufficiency in food grains production has ensured a high priority for agricultural sector in the successive development plans of the country. Agricultural production is grossly affected by attack of pests/diseases on various crops and the losses in food grains only are to the tune of Rs 90,000 crores each year in India. The prevention of such losses needs substantial consideration and accordingly forewarning of pests and diseases is essential for taking timely control measures. These are also required for assessing losses. Pest/disease infestation in crops is highly influenced by meteorological factors. The weather based modeling for early warning of pest/disease infestation may provide appropriate tool for investigating and predicting pest/disease status.

The steadily-increasing human population has led to a rise in the demand for food. As more land comes under agricultural cultivation there will be more pressure on natural ecosystems. Climate change will affect agricultural yield directly because of aberrations in temperature and rainfall, and indirectly through changes in soil quality, pests and diseases. In particular, the yield of cereals is expected to decline in India, Africa, and the Middle East. As the temperature rises conditions will become more favourable for pests such as grasshoppers to complete a number of reproduction cycles and thereby increasing their population. In the higher latitudes (in the northern countries) agriculture will benefit with the rise in temperature as the winter season will be shorter and the growing seasons longer. This will also mean that pests that will move towards the higher latitudes as the temperatures rise. Extreme weather conditions such as high temperature, heavy rainfall, floods, droughts, etc. will also affect crop production.

Introduction

Information technology is set to become important in agriculture in the coming years. In the last few decades, the application of computers and communication technologies has led to the development of a plethora of information of all types in the area of plant protection science. These information bases are available on CD-ROM, on-line form in various hosts and via mail over internet, multimedia data bases, Decision-Support Systems (DSS)/Expert Systems (ES), Simulation Models (SM), etc.- to cite a few of the latest developments. Further, cyber space is fast emerging as an area of information technology, particularly in the field of crop pest management (Srivastava and Swain, 1998). The application of information technology in pest management has been one of the most exciting developments in the field over the last decade. From the 1960s, the entomologists began using computers for spray scheduling, population modeling, exploring control strategies and managing pest monitoring data. More recently, computers are being utilized in pest management delivery systems and decision support systems (DSS) designed to enhance decision making.

Introduction

Taxonomy, which includes identification and classification has transformed into systematics and biosystematics in the recent times and is integrating itself into the biodiversity, which is now a global phenomenon occupying the main thrust of human life. The magnitude and cause of this biodiversity is the central problem of taxonomy and one of the key problems of science as a whole, not to speak of pest management. The science of taxonomy started in the late eighteenth century by a Swedish biologist, Carl Linnaeus who with a small number of similar minded scientists pioneered a standard system of using two Latin names for an organism, denoting “genus” and “species” that is still in use. This led to referring of biological organisms by an universally agreed name and identity, and further providing means for their realistic classifications. When these identifications and classifications got strengthened further with accumulated biological knowledge, it allowed the development of modern biology on a sustainable and stable base. In addition, in the recent times taxonomy has become more demanding subject for areas in science and technology, which are dependant on access to accumulated experience and knowledge for their survival and development. Insect pest management is one such area where taxonomy provides the essential scientific basis, without having any claims of its own and integrating itself in such a manner that its role is difficult to delineate precisely.

Introduction

Food security is an agricultural issue that has political connotations in the world and more strikingly so in the developing world, where systems of governance has assumed and lost power on this issue. Agriculture not only contributes to the overall growth of the economy but also provides a vital livelihood base, employment and food security to the majority of the country’s population. Recent food price hikes have drawn the attention of the world’s policy-makers and news media to food security which triggered a wide variety of policy responses throughout the world. It threatens the food crisis and livelihood of millions of peoples suffering from hunger and poverty.

Introduction

Huge population in the developing countries requires increased amounts of food and fiber from a shrinking agricultural land base. Intensification of agriculture through expansion of irrigation facilities, introduction of high yielding varieties and application of increased amounts of agrochemicals has been in progress. Besides, the cultural practices like spacing, crop rotations, sowing times and tillage methods have been modified to achieve maximum productively per unit time from the available land. However, along with various technological achievements, sever outbreaks of insect pests, diseases and weeds in agricultural crops have also occurred. Many hitherto unknown species have assumed serious status and some of the serious pests have developed resistance to one or more groups of pesticides. In addition, pesticides have contaminated different components of our environment and pose a potential health hazard to consumers. Therefore, the future pest problems will have to be tackled in an environmentally benign manner as a part of a sustainable crop production technology (Dhaliwal and Heinrichs, 1998; Koul et al., 2004; Koul, 2008).

Introduction

With the introduction of chemical pesticides in India during 1947 when 250 tonnes of DDT was imported for Malaria eradication programme, there is a steady increase in consumption and at present about 25 per cent of the cropped area is covered by pesticides. Their use has helped in increasing the productivity over the years. The consumption pattern of different groups of insecticides has indicated the same trend. The Indian pesticide industry with 85,000 MT of production in is ranked second in Asia (behind China) and twelfth globally. The Indian pesticides industry is dominated by insecticides where herbicides and fungicides are the key segments globally. Among the pesticides, insecticides account for 57 per cent, fungicide 28.7 per cent and herbicides 14.0 per cent during the year ending 1997-98. Owing to the ban of highly persistent organochlorine pesticides, there is decrease in the trend. Among the different crops, cotton consumes 44.5 per cent of the pesticide worth of Rs.2462.13 millions, even though it occupies only 5 per cent of the cropped area. Cotton is followed by rice (22.00% of pesticides) and other crops.

Introduction

One of the triumphs of modern agriculture is the increase achieved in the productiveness of land, measured by yield of crops per hectare or per acre. This has enabled the earth to support a much greater population than would have been possible in past centuries. The increased productivity of the land is a result of scientific and technological progress in plant breeding, in control of pests and weeds, in irrigation and in fertilizers to supplement natural reserves of plant foods. But this progress makes it more difficult to fulfill one specific requirement of many crops: pollination. Pollination of flowers is an essential step in the sexual reproduction of angiosperms. Most angiosperm species rely on insects or other animals, rather than wind, for transfer of pollen among individual plants. The pollinators in turn benefit by obtaining floral resources such as nectar or pollen. Pollination is not only mutually beneficial to the interacting plants and animals, but also serves humanity directly through the yield of many crops, and indirectly by contributing to the healthy functioning of unmanaged terrestrial ecosystems (Costanza et al.,1997; Nabhan and Buchmann, 1997; Klein et al., 2007; Abrol, 2007 and 2008).

Introduction

The increasingly precarious situation facing the world’s hill regions has been the focus of a growing level of awareness over the past two decades. The high altitude regions offer a challenge to agricultural development agencies which is shared by many hill areas of the world characterized by marginality, extreme diversity, environmental fragility and complex smallholder farming systems. There is justifiable concern relating to the conservation of hill and mountain ecosystems, to the extent that the concept of sustainability has been adopted as a broad slogan by the environmental movement (Lele, 1991).

Conditions specific to mountain regions, such as inaccessibility and diversity have placed a high premium on large families, encouraging population growth. Children are essential to family subsistence strategies offering free labour, and they are consequently considered to be a source of wealth. Population control measures in these regions have ignored this scenario (Sharma and Banskota 1990; Jodha, 1991).

Weeds pose serious problems to agriculture and environment. Weeds are plants that are undesirable to human activity at a particular time and place, and therefore, weeds will always be associated with human endeavours. In agriculture these not only cause huge reductions in crop yields but also increase cost of cultivation, reduce input efficiency, interfere with agricultural operations, impair quality, act as alternate hosts for several insect pests, diseases and nematodes. In non-crop areas, they affect aesthetic look of the ecosystem as well as native biodiversity and health and quality of life. Weeds are a big constraint in crop production and are responsible for heavy yield losses in almost all the crops. “Being fore-warned is fore-armed” is the principle behind preparation of perspective plans. Weeds are big constraints in crop production and are responsible for heavy yield losses in all crops. Out of the losses due to various biotic stresses, weeds are known to account for nearly one third. Proper management of weeds is essential to meet the growing demand of foodgrains, pulses, oilseeds and other crops by the ever increasing population. As per the projections of IFPRI, Washington there is a likelihood of shortfall of 41 per cent in the food grain production in the country by 2020.