Preface India having around 180 million heads of cattle, 100 million buffaloes, 185 million heads of caprine and ovine population which makes her highest milk producing country in the world. Not only that beef and buffen, mutton and chevon produced but also and exported in significant amount to gulf countries. Feed ingredients available in India is mostly crop residue and agro- industrial  by-products, the sector is overlooked, though significant output is achieved. Poor, landless, marginal and small farmers are raising the ruminants without knowing the nutritive value, composition and requirement of the animal. Not from the farmers point of view, academician, researcher and students may also get vast information presented in the book ‘Text Book of Ruminant Nutrition’. To ensure the book will go to further edition, advice may send to the author at earliest. The author is highly thankful to friends, colleagues (at Kargil and Shuhama) and scientists at DCN Division, NDRI, Karnal for making books, journals, magazines available to me. Finally thank to my wife and kid, who always contributed to the preparation of transcript and inspiration for finalization of writing the book.

1.1 Introduction Agriculture and allied sector contributes nearly 18 percent of gross domestic product in Indian economy and more than 70 percent population is dependent on agriculture and allied sector. In this sector, livestock is an integral part and it provides essential commodities and livelihood to the majority of its population. Livestock sector provides sustainability and stability to the national economy by contributing farm energy and food security. During last decade, the annual growth rate for livestock population maintained and in contrast the crop production remained stagnant or increased marginally. Between 1983 and 1999, the per capita consumption of milk increased by 37 percent and meat, egg and fish by 24 percent.

Every nutrient has its specific functions to play in the biological system. As we know there are six nutrients i.e., water, carbohydrate, protein, fat, minerals and vitamins and each of these have different functions, it will be discussed separately for each nutrients. 2.1 Water Water is the ideal dispersing medium because of its solvent and ionizing powers which facilititates cell reaction and due to its high specific heat which helps to absorb the heat of these reactions with a minimum rise of temperature. Lean adult body contains about 70 percent of water, though the amount varies from embryo to mature animals.

Developments of feeding standards Feeding standards are statements or quantitative descriptions of amounts of one or more nutrients needed by the body. Since the beginning of nineteenth century, scientists worldwide started formulation of standards for feeing the livestock and poultry and as such with the advancement of science the standards were developed from time to time. For convenience all such standards are grouped under major  3 headings based on principles of standards. These are comparative type, digestible nutrient system and production value type.

4.1 Ration and balanced ration A ration is the feed allowed for a given animal during a day of 24 hrs. The feed may be given at a time or in portions at intervals. Balanced ration may be defined as the ration that provides all essential nutrients to the animal in such a proportion and amounts that are required for the nourishment of the particular animal for 24 hrs.

The potential value of any feed for supplying a particular nutrient can be determined by chemical analysis but the actual value of the feed to the animal can arrived at only after making allowances for inevitable losses that occur during digestion, absorption and metabolism. The first tax imposed on feed is that represented by the part of it which is not absorbed and excreted in the feces.

This may be defined as the factor present in feeds/ fodders or trees leaves and impair some aspects of animal metabolism, produce adverse biological effect in animal production. These are referred mostly as toxic factors because of the deleterious effects they produce when taken by the animals. The term ‘toxic factor’ however, is misleading because there is an implication that the substances are lethal beyond certain level of intake.

Diseases of metabolic origin are commonly known as metabolic disease viz., bloat, acidosis, milk fever, hypomagnesimia, pregnancy toxaemia etc. However, few common metabolic diseases encountered in herd/ flock management are discussed in the chapter. Among these diseases bloat, acidosis and ketosis are generally occurs due dysfunction in rumen. In the rumen, microbial fermentation occurs due to unique structures and environment. Microbes converts fibrous feeds which are of no use for human beings to important product viz., milk meat, hair and fibre etc. Some bacteria and protozoa have isolated from rumen by the researchers and with their fermented products and pathways. Name of the fermented products with the products is presented in the following Table 24.

Further Reading ARC. Agricultural Research Council. 1965. Nutrient Requirement of Farm Livestock: Ruminants. London. p. 243. Beck, T. and Gross, F. 1964. Ursachen der nutersciedlichen Haltbarkeit von Garfutter. Das Wirtschafrceigene Futter. 10: 40-45. Blaxter, K.L. and Graham, N. Mec. 1955. J. Agri. Sci. Camb. 46: 292. Chakrabarty, A. G. 1981. Detoxification of corn. J. food. Prot. 44: 591-592. Chalupa, W. and Sniffen, C.J. 1996.  Protein and amino acid nutrition in lactating dairy cattle - today and tomorrow. Anim. Feed Sci. & Tech., 58: 65-75. Cheeke, P. R. and Shull, L.R. 1985. Mycotoxins. In: Natural toxicants in feeds and poisonous plants. pp. 393-477. Fenwick, G.R., Henry, R.R. and Mullen, W.J. 1983. Glucosinolates and their breakdown product in food and food plants. CRC Crit Rev. Food Sci. Nutr. 18: 123-201.