Preface Sustainable livestock production depends mainly on feeding balanced and economical ration to livestock. Feed shortages both quantitatively and qualitatively limit livestock production. The cheapest source of high quality feed is forages. Forages are usually consumed fresh by domestic animals. However, it is possible to conserve them for use during future periods of feed shortages. When forage growth exceeds herd requirements, one of several strategies available to keep pasture quality high is fodder conservation as hay and silage making. Hay is preserved by drying. Hay is the oldest, and still the most important, conserved fodder, despite its dependence on suitable weather at harvest time. Silage involves natural fermentation, which produces lactic and other acids, which preserve the forage. Hay and silage helps to preserve forages at optimum nutritional value and ensure forage availability from the present to the future especially during drought, flood or disaster.  Forage Conservation Techniques was written in response to the need for a complete textbook on forage conservation methods and utility of the conserved forages to livestock. This book covers in-depth discussions of all theoretical and practical aspects of hay and silage preservation and their use in livestock feeding. Mechanism of silage and hay preservation, role of microbes and nutrients in forage preservation and quality assessment have been written in detail. A chapter on analytical techniques deals with methodology of analysis of nutrients and other parameters to judge the quality of hay and silages. Special emphasis has been given to recent advances in silage microbiology, preservatives and quality assessment, which will help to gain better understanding of ensiling process and to develop better additives. There is also a list of references at the end of each chapter, so that students can pursue the literature beyond that presented in this book.

Livestock production is an integral part of agriculture and plays a significant economic role in most developing countries. It contributes to poverty alleviation, food security and provides elements that are essential to the national economy. Livestock production accounts for 40% of the gross value of the agricultural production globally and this figure is likely to go up, as the demand of livestock products is increasing rapidly with the increase in income and urbanization (FAO, 2012). For poor farmers, animal ownership ensures varying degrees of sustainable development and economic stability. Livestock provide a stable cash reserve independent of inflation and are an important source of traction. Livestock are closely linked to the social and cultural lives of several million people. Quality and quantity of feed is essential for optimum animal productivity. Inadequacy of quality animal feed resources is most often the crucial factor for livestock production. The success of livestock is greatly dependent on continuous supply of good quality nutritious feed at competitive price. Poor nutrition of animals has been identified as the major constraints to animal production across the developing world (FAO, 2000). Feed is the major input cost in animal production system, accounting for 65-70% of the total rearing cost.

Silage is the material produced by controlled fermentation of forages or crop residues with high moisture content. The objective of silage making is to preserve the harvested forages by anaerobic fermentation in which soluble carbohydrates are converted into acids. Due to acid produced, pH of a well-ensiled product becomes so low that all life processes come to a halt and the material remain preserved so long as it remains in airtight storage. Soluble carbohydrate present in forage is converted to lactic acid which drops the pH to a level sufficient to inhibit any further biological activity in the ensiled forage mass (McDonald, 1991). Fresh forage crops, such as maize, grasses, legumes, wheat and Lucerne, can be preserved by ensiling. It is essential to have a good microbial fermentation process to produce high quality silage. Good silage is achieved by discouraging the activity of plant enzymes and undesirable micro-organisms and encouraging the dominance of lactic acid bacteria. A good fermentation process is not only dependent on the type and quality of the forage crop, but also on the harvesting and ensiling technique. Silage-making is a managemental tool that allows producers to match feed resources (forages, crop residues, agro-industrial byproducts, etc.) with feed demand for a dairy herd.

Ensiling is the term given for all physical and chemical changes that take place when forage with sufficient moisture content (60-65%) is stored in the absence of air for silage preservation. Silage fermentation is an exceptionally complex process involving biochemical interactions among the forage, microbial populations and the ensiling environment. Successful silage production depends upon the promotion of the fermentation brought by beneficial bacteria. The process is based on spontaneous lactic acid fermentation under anaerobic conditions. The lactic acid bacteria ferment the water-soluble carbohydrates in the crop to lactic acid, and to a lesser extent to acetic acid. Due to the production of these acids, the pH of the ensiled material decreases and spoilage micro-organisms are inhibited. The ideal characteristics of material for silage preservation are: DM content above 20% and an adequate level of fermentable substrate (8-10 percent of DM) in the form of water soluble carbohydrate. The ensiling material should also ideally have a physical form that allows easy compaction in the silo. Materials such as maize stover, sorghum stover and grass can be ensiled successfully, while crop residues such as rice and wheat straw, with low water soluble content, do not fulfill these requirements, and therefore pre-treatments, such as fine chopping or use of additives, or both, may be necessary.

A silo is an airtight to semi-airtight structure designed for the purpose of preservation and storage of high moisture feeds as silage.   Role of the silo in silage making Silo has only three functions in the ensiling process:     1.    To provide a solid surface to permit compaction of the mass to eliminate air;     2.    To protect the ensiled materials from air and water during the storage period;     3.    Where desired, to aid in the removal of silage by providing a base for unloading equipment.

Successful preservation of high-moisture forage and other crops depends upon the controlling the activities of microbes, particularly bacteria. Ensiling generally controls microbial activity by a combination of an anaerobic environment and a natural fermentation of sugars by lactic acid bacteria on the crop. The silage microflora plays a key role in the successful outcome of the conservation process. Therefore, it is important to understand both the microorganisms that are present on the crop at ensiling and how ensiling preserves the crop, inhibiting detrimental microorganisms. The crop at ensiling contains both aerobic and anaerobic microorganisms and a range of both bacteria and fungi that affect silage quality.

Silage fermentation is a complex process involving biochemical changes by microbial populations and the ensiling environment. The chemistry and microbiology of silage fermentation are linked, but the microorganisms are the dominant factor in the fermentation process, and they have the main influence on the quality of the end product. Many species of microorganisms are involved in the fermentation process, and their relative importance varies according to the prevailing conditions. As these conditions change during the fermentation process, the microorganism population changes accordingly. Lactic acid bacteria and clostridia are two main categories of microbes responsible for biochemical changes in silage.

Silage fermentation is a dynamic process that is affected by variety of factors. The primary goal of making silage is to maximize the preservation of original nutrients in the forage crop for feeding at a later date. Unfortunately, fermentation in the silo is a much uncontrolled process usually leading to less than optimal preservation of nutrients. In order to assist in the fermentation process, various silage additives have been used to improve the nutrient and energy recovery in silage, often with subsequent improvements in animal performance (Henderson, 1993; Bolsen et al., 1996; Muck and Kung, 1997; Kung and Muck, 1997; Muhlbach, 2000). Their main functions are to either increase nutritional value of silage or improve fermentation so that storage losses are reduced. The benefits obtained from silage additives depend upon their influence on the silage fermentation process. These benefits are usually measured by the reduction in fermentation losses and/or improvement in silage quality and feeding value.

Quality of silage is determined by nutrients content and intake potential of the silage. High quality silage is a stable feed, made from high quality pasture, which is preserved in the absence of oxygen by a high quality fermentation, to minimize any loss of feeding value. It is not possible to produce high quality silage from low quality pasture, no matter how good the fermentation is. The silage quality is generally used to indicate the success of fermentation and not to evaluate the feeding value of the silage. However, the fermentation quality and nutritional value of the silage are usually highly correlated because a poor fermentation can result in great loss of the digestible nutrients (Sutoh et al., 1970; Uchida and Sutoh, 1973). Therefore, both the quality of the ensiled pasture and the quality of the fermentation must be considered.

Silage fermentation is a dynamic process involving interactions among the forage, microbial populations and the ensiling environment. A good fermentation process is not only dependent on the type and quality of the forage crop, but also on the harvesting and ensiling technique. There are various factors that influence the fermentation process and ultimately the nutrient composition and quality of ensiled feed. These are as follows: 1. Plant Factors Forage characteristics at the time of ensiling are the predominant factor which determines the final quality of silage. Factors such as type of forage to be ensiled, maturity, DM content and WSC content of that forage, all influence the ease of ensiling and ultimately the quality of silage that is produced.

It is recognized in developed countries that the production of silage of high quality cultivated forage can be a valuable component for the development of a high-performing and low-cost system of animal production, using a relatively low level of purchased concentrates. However, this appears inappropriate for smallholders in tropical countries, primarily due to lack or high cost, or both, of equipment for harvesting and conservation and production of cultivated forage being often limited due to lack of available land. Many agricultural, agro-industrial and fishery by-products have potential as animal feeds. Most farmers in developing countries rely for their food security on the cultivation of cereals, root crops and high-value crops such as fruits and vegetables, which understandably take priority in the allocation of land. Fruit, vegetables and root crops are increasingly integrated in the farming system and play a key role as staples in the human diet in most developing countries.

Objective of the conservation of forage is to preserve as much as of the crop nutrient as possible. However, during ensilage loss of nutrients occurs. There are five sources of loss. Theses are:       (a)    Field losses      (b)    Oxidation or respiration losses       (c)    Fermentation losses     (d)    Effluent losses      (f)    Aerobic deterioration

Feeding silage is also an important part of the process. Silage can be fed to all kinds of animals. Silage is suitable for feeding 6-7 weeks after ensiling. Purposes of silage feeding are drought feeding, production increases, an aid to pasture or crop management, utilization of excess growth, balancing nutrients in the diet, and the storage of wet feed products. Silage is most likely to be profitable when used to increase productivity or balance nutrient content of the diet.   Feeding value of silage is defined as the product of the nutritive value and potential voluntary intake of the forage (Wheeler and Corbett, 1989).

Forage preservation as silage is a key component of high input (zero-grazing) systems (Mannetje, 1999). It has allowed producers to intensify the productivity of the land and the productivity of the livestock. Large quantities of forage can be conserved in a short time, forage conservation is less weather dependent and thirdly, silage is well suited to mechanization. However, a major disadvantage associated with silage making is that the feeding value of the resultant forage is reduced relative to that of the original crop. Ensiling offers many advantages over haymaking.

Feeding of green and succulent fodder is of utmost importance to farm animals. Grazing fresh forage year round at the optimal stage of maturity would supply the highest quality and most palatable form of feed in any livestock operation. In most part of the world, green fodder is limited to a particular season only. Because of fluctuations in seasonal growth and plant maturity, excessive biomass in the spring, it is necessary to harvest and store forages to maximize both quality and productivity. One of the important form of conservation practiced on a wide scale is hay making. Hay making is an art in which the fodder is kept for future use in lean period. Since it contains large quantity of moisture it is to be dried properly to increase its keeping quality without reducing its nutritive value. The objective of hay making is to achieve a rapid moisture loss after cutting so that the forage can be romoved from the field with minimum losses from weathering and microbial degradation (Bareebam, 1992).

Hay quality really means feed value. The ultimate test of hay quality is animal performance. Quality can be considered satisfactory when animals consuming the hay give the desired performance.   Characteristics of Good Quality Hay     1.    Hay should be nutritious therefore prepared form plants cut at an appropriate stage of maturity when it has the maximum nutrients.       2.    Good hay should be leafy. The leaves are generally richer in proteins, minerals and vitamins then other parts of the plant.     3.    Hay should be green in colour. The green colour indicates the amount of carotene which is precursor of vitamin A. The green colour should be preserved by minimizing the bleaching, leaching arid fermentation losses.

Storage of hay at higher moisture contents may lead to some heating due to the activity of aerobic micro-organisms and possibly some plant respiration. The warm, moist conditions in hay will provide the ideal environment for growth of spoilage bacteria, e.g. Bacilli and yeasts, moulds and fungi. These organisms utilize the energy and protein of the hay and can lead to a substantial increase in their respective populations. Their action leads to the following reaction:-  Hay (plant sugars) + oxygen ® Carbon dioxide + water + heat   The resultant heating causes a reaction between the carbohydrates and proteins rendering both less digestible as temperatures continue to increase. The best opportunity to reduce hay-harvesting losses is by shortening curing time. A combination of mechanical conditioning, chemical conditioning and high-moisture baling help accomplish this goal (Collins, 1988; Mahanna, 1994).

Haylage or baleage or round bale silage, is a somewhat newer method of preserving forage. Haylage is simply forage that is baled at higher moisture content than dry hay and then stored in a sealed plastic wrap. Because of the high moisture level and air-tight environment, the forage ferments and is preserved by acid production during fermentation. The higher pH values associated with baleage are related to a slower fermentation process. During the respiration stage of the ensiling process the oxygen that is trapped in storage is rapidly consumed by aerobic bacteria. Anaerobic bacteria, which survive in the absence of oxygen, begin to grow and multiply in the fermentation stage and convert the plant sugars into organic acids- mainly lactic acid and acetic acid. With production of acids, the pH of the silage is reduced from an original level of 7.0 to a final ideal pH of 4–5. Typical large bale haylage has a pH of 4.5–5.5. Fermentation ceases when bacteria growth is stopped by the accumulation of acids. The haylage will then remain at a stable pH with no bacterial growth and can be preserved for a long time, providing there is no exposure to air. Harvesting forages with a long fiber usually results in a slow release of the plant nutrients necessary for the growth of acid producing bacteria. This generally results in less fermentation in the baleage than in chopped silage.

Analyzing feeds for nutrient content is essential for proper balancing of livestock rations. This is especially essential for those feeds that have undergone the fermentation process. Silage samples should be analysed for dry matter, protein fractions (degradable and undegradable protein, soluble protein, and heat damaged protein), ADF, NDF, mineral content and energy. In addition to these components, lactic, acetic, and butyric and propionic acids, pH, ammonia nitrogen, ethanol, and yeast and mold counts are also quantified.

A Acetic acid 16, 18, 19, 40, 43, 44, 45, 47, 48, 53, 55,57, 59, 65, 67, 71, 73, 81, 82, 85, 86, 87, 122, 168, 169, 170  Acetoin 58  Acid detergent fibre 208, 209 Aerobic deterioration 17, 34, 36, 44, 45, 71, 72, 74, 90, 97, 98, 111, 113, 115, 116  Aflatoxin 126  AIV process 70 Alanine 56, 57, 59 Amides 58, 82,  Amines 15, 41, 42, 44, 56, 57, 58, 82, 83,  84 Amino acids 15, 40, 41, 42, 43, 56, 57, 68, 112, 134 Ammonia 15, 42, 44, 55, 56, 57, 64, 67, 68, 69, 72, 80, 82, 83, 84, 85, 87, 91, 95, 112, 114, 122, 123, 127, 169, 172, 173, 185, 188, 189, 190, 191, 192, 196 Anaerobiosis 47