Agricultural Science

Animal Nutrition

The food given to farm animals is generally known as livestock feed of simply feed. Animals need feeds for growth repair of worn out tissues, energy and the general well being of the animals.

Effects of feed shortage in animal production

Feed shortage will lead to the following effects in the animal production

  1. Loss of weight or low birth weight
  2. Poor reproduction or delay in puberty or late maturity
  3. Poor milk, meat and egg production is recorded
  4. Could also lead to high death rate
  5. Increase in susceptibility to diseases
  6. Slow growth rate of livestock
  7. Draft animals becomes weak and unable to work

Classification of livestock feed

  1. Basal/energy feed of carbohydrate concentrate
  2. Protein concentrate
  3. Mineral / vitamins supplement
  4. Roughages


These are mostly easily digestible carbohydrates with low protein content. They constitute 60 to 90% of practical livestock rations.

They have low fibre content thus need to be supplemented by high protein feeds.


Roughages are feeds that are rich in plant fibre. They can be prepared

in the following ways:

  1. Hays: these are sun-dried forage packed and kept for feeding animals.
  2. Silage: these are forage crops cut fresh, compressed in a pit and allowed to ferment.
  3. Straw: this consists of dried plant materials as maintenance ration during periods of food scarcity.
  4. Forage: this refers to grasses and legumes used for feeding farm animals.
  5. Fodder: these are crops grown specially to feed farm animals, example: corn, groundnut, legumes, grasses, etc.



  1. It has crude fiber content less than 18 percent
  2. It is high in protein
  3. Low in carbohydrates and fats
  4. Low in fibre
  5. Highly digestible
  6. Low in minerals



  1. They are required in small quantity in the feed
  2. They supplement basal and protein concentrate
  3. Low in energy
  4. Low in protein
  5. Low in fibre
  6. High in minerals and vitamins
  7. They are necessary for growth and development
  8. They largely aid food digestion
  9. They largely aid resistance to diseases
  10. They include minerals, vitamins and essential amino acids.

Methods of preparing feed ingredients

  1. Blood meal: collect fresh blood from the abattoir and allow to clot in the open. Heat the blood to reduce the moisture content and kill the pathogens. After heating the blood now in lumps is dried and crushed into powder.
  2. Fish meal: fish meals can be prepared sin two major ways, these are :dry and wet processes.
    1. Dry process: collect fresh fish, sun-dry or smoke it to reduce the moisture content, and then ground it into powder.
    2. Wet process or Rendering: collect the fresh fish, heat it with steam, then, dry it and crush into powder.
  3. Groundnut / palm kernel cake: collect the seeds of groundnut /palm kernel, crush and press to remove the oil .then press the remnants with machine to form cakes, which are dried.
  4. Cotton seed meal: collect cotton seeds, grind them and extract oil from oil from the crushed. Dry the residue or cake later.
  5. Bone meal : this can be prepared in two ways :
    1. Dry process : collect bones from the abattoir , dry and burn them ,then crush the burnt bones to the desired textures
    2. Wet process or rendering: collect bones form the abattoir, heat with steam, crush and dry the crushed bones.
  6. Maize / Guinea corn: remove grains from the cobs, dry them and crush or grind to desired texture.

Feed ingredient can be prepared or process for animals by making into mash and pellets while some have to be cooked before it can be fed to the animals.

Basics for Livestock Nutrition


The most important aspect in keeping livestock healthy and able to produce is a proper nutritious diet. Cattle belong to a class of animals called ruminants. This group also includes sheep and goats. Ruminants have a digestive system which allows them to efficiently digest and absorb most of their nutrients from forages. There are four compartments in the beginning of the digestive tract, one of which is called the rumen that contains near 50 gals of fluid and ingested forage. The rumen has a large population of microbes, mainly bacteria and some protozoa, which allows for the degradation of the fibrous material in forage. Much of the initial digestion of feed is done by microbes in the rumen. Sheep and goats are also ruminants, but the initial digestive tract compartments are of different proportions and configuration than cattle. They are often referred to as “small ruminants”. The horse is a non‐ruminant herbivore. These animals do not have a multi‐compartmented stomach as cattle do, but are able to consume and digest forage. The cecum and colon, parts of the large intestine, serve the somewhat same purpose for the horse that the rumen does for the cow. Llamas and alpacas are “pseudo‐ruminants” because they have three continuous compartments in the fore digestive tract instead of four like ruminants. Swine utilize different types of feed than ruminants, due to the differences in their digestive systems. Swine are monogastrics, meaning they only have one stomach which is similar to that of humans. Usually grains are the main part of a swine’s diet. They can eat a portion of their diet from pasture, although the forage from the pasture needs to be of high quality. The diet for livestock is usually referred to as a ration and a balanced ration is the amount of feed that will supply the proper type and proportions of nutrients needed for an animal to perform a specific purpose.

The Six Basic Components of a Ration

Water ‐ Water is often over looked but is the most critical component of any ration. It is essential in allowing most of the physiological functions in the body. Water has been a difficult nutrient to determine the actual requirement for many livestock primarily because water is usually provided free of choice. When water is limited in a ration, the dry matter intake is reduced and the correct amount of nutrients for the animal is restricted.

Functions of water

  1. Water is provided for drinking purpose
  2. It is used for metabolic and digestion of food
  3. Water is also used for dipping / drenching animals against ectoparasites and endoparasites
  4. Water equally used for washing or cleaning animals
  5. It is used for cleaning floors ,pens or for sanitation purpose
  6. Water is also used for milk and meat processing
  7. Water is part of the body of any animal
  8. It is used for maintenance of body temperature
  9. Water is used for irrigation of pastures
  10. Water is a constituent of milk, egg, and meat.

Protein – Protein is needed for the structuring of muscles, skin, hair and internal organs and is the only food source of nitrogen. Crude protein is the total protein content of a feed. Since proteins contain 16% nitrogen on average, knowing the total amount of nitrogen will determine an approximate amount of protein in the feed. Proteins are composed of amino acids and each protein has a variety of the 22 amino acids in different quantities. Many amino acids are synthesized in the body, but there are eight amino acids that are not synthesized and need to be provided in the ration. These are called essential amino acids. The digestion and absorption of amino acids and nitrogen is different in each species of livestock.

Functions of Protein

  1. Protein are essential for growth of young ones
  2. They are used for the repair of worn out tissues
  3. They are used in the formation of gametes in reproduction
  4. Meat, egg and milk production in livestock depend on the protein level in the animal.
  5. They required in the production of enzymes and hormones in the body of livestock
  6. Protein is essential for the sustenance of life
  7. They are also necessary for flesh build up
  8. Protein provides the raw materials for building protective covering such as hair
  9. They are also used in the formation of digestive juice and other secretions of the intestine.
  10. Proteins are equally useful in the production of of antibodies

Energy ‐ Energy allows the animal to do physical work. It also provides the ability to grow, lactate, reproduce, and enable other physiological functions such as feed digestion. Energy is not actually a nutrient but a total caloric value of a feed. There are several chemical, mechanical, and mathematical methods to determine feed energy values.  Some of these are called digestible energy, metabolizable energy, net energy, and total digestible nutrients. A total digestible nutrient (TDN) is the energy value most commonly used in simple rations. Each ingredient in a ration has a different digestible energy value and of those values there is a different amount of energy that is metabolized and used in the body.

Fiber – Crude fiber is an estimate of structural carbohydrates found in plants and grains. It has a varying amount of digestible material from high to low in cellulose and lignin respectively. Fiber limits the energy value of plants for monogastrics such as pigs, but the microbes in the digestive tracts of the other livestock species mentioned above are capable of utilizing the fiber which provides energy in the ration. Fiber also provides the necessary bulk in the digestive tract and regulates the time of passage of food. This helps to maintain a population of microorganisms which are critical for healthy digestion.

Minerals ‐ Minerals are very much needed for the physiology of structure, metabolic and immune functions in the animal. There are two classifications of minerals. Macro minerals (calcium, phosphorous, sodium, chlorine, magnesium, potassium, and sulfur) are those that are required in the most amounts in a ration compared to minor minerals (iron, copper, molybdenum, manganese, zinc, cobalt, iodine, and selenium, and others) which are needed in less amounts.

Vitamins ‐ Vitamins are similar to minerals in that they take part in many physiological functions, including coenzymes for metabolic functions and antioxidants, which are compounds that help prevent damage to cells. Vitamins are grouped into two categories, fat soluble and water soluble. Many of the important vitamins for forage eating animals are either synthesized by microbes in the digestive system, obtained from sunlight, or are stored in the liver. Many of those vitamins that are not made in the animal are easily provided in adequate amounts in the forage.

Fat and oil

Composition: fat are composed of carbon, hydrogen and oxygen

Sources : these are palm oil , palm kernel cake ,groundnut cake , coconut meal ,  linseed cake ,cotton seed cake , milk , lard , tallow,


  1. Fats provides more energy than carbohydrates
  1. Fats supply essential fatty acids and fat build-up
  2. They also provide fat soluble vitamins
  3. They improve the palatability of diet
  4. Fats helps in the maintenance of body temperature
  5. They prevent dustiness of feeds

The Basics for Livestock Rations

Every ration will be different depending on species, age, size and weight, gender, stage of reproduction, demands for production or work, and environment. The proper formulation of rations for livestock is dictated by appropriate nutrient requirements for each type of animal under a variety of conditions. The National Academy Press publishes a series of tables about nutrient requirements for livestock. The National Research Council (NRC) compiles the data for these publications which can be purchased or read online from the web site listed below. In addition to knowing the nutrient requirements, it is also necessary to know the nutrient composition of each feedstuff per ration. While the book value forage analysis is good information to compose a proper ration, when possible it is best to sample the individual feed stuff used and have it analyzed. The greatest variation between the book value and the actual value is in forages.

Note: Ruminants are animals whose digestive system contains fermenting microbes that help to digest forage.

Note: Components of a Ration:








Diet: a diet is defined as the amount of feed regularly given to or consumed by the animal. It is formulated to meet specific metabolic or physiological function such as: growth, lactation, maintenance of pregnancy, reproduction, egg laying etc.

Ration: ration is the total supply of feed given to an animal in a 24 hour period. In other words, ration is the amount of food taken by an animal per day

Balance Ration: a balance ration is the feed containing all essential nutrients in the correct quality and in adequate proportion for feeding animals.

Factors normally considered when deciding the type of ration to feed an animal

  1. The purpose for which the animal is being kept
  2. The class of animal
  3. Age of the animal
  4. Animal’s condition of health
  5. Management system
  6. Physiological state of the animals

Types of Ration

There are two types of Ration

  1. Maintenance Ration : this is the type of ration given to the animals just to maintain normal functioning of the body
  2. Production Ration: this is the type of ration given to the animals to enable them produce.

Categories of animals that require production ration are:

  1. Lactating Animals : for milk production
  2. Weaning Animals : for increase growth
  • Pregnant Animals : for maintenance of the foetus
  1. Fattening animals : for extra addition of more flesh or meat
  2. Broilers : for rapid growth
  3. Layers : for more egg production
  • Steaming up or flushing : for animals before mating to produce more ova/ovum

Malnutrition in animals

Malnutrition is a condition in which an animal shows evidence of nutritional deficiency .it occurs when a ration does not supply all the essential nutrients in the right proportion and quantities. In other words ,it result when an animal takes in insufficient food or eats diets which is deficient in one or more nutrient like proteins, carbohydrates ,minerals ,and vitamins .this eventually results n nutritional diseases.

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