Smallstock Nutrition

What is Nutrition ?

Animals eat to supply the tissues with the nutrients required to fuel physiological processes of maintenance, growth, fat deposition, lactation and work.

A common definition of nutrition is:
"The process of nourishing or being nourished, especially the process by which a living organism assimilates food and uses it for growth and for replacement of tissues".

A textbook definition may be more like:
Nutrition involves various chemical and physiological activities which transform food elements into body elements.

Nutrition can also be seen as the science which interprets the relationships of food material to the functioning living organism.

The question of nutrition is fundamental to keeping livestock. In practical terms smallstock keepers need to understand that the provision of an adequate diet and nutrition for their livestock may be a combination of naturally sourced food material and supplementary feed of some sort.

Small ruminants (sheep and goats) require energy, protein, vitamins, minerals, fiber, and water. Energy is usually the most limiting nutrient, whereas protein is normally the most expensive. Deficiencies, excesses and imbalances of nutrients, particularly vitamins and minerals, can limit the performance of an animal and are likely to lead to various health problems. Fibre, roughage or bulk is necessary to maintain a healthy rumen environment and prevent digestive upsets. Water is an essential feed ingredient, yet often the most neglected.

Feed and Feeding

Feeding is the act of providing a balanced ration to the animals which contains all the essential nutrients needed for the preservation of life. Water, proteins, carbohydrates, fats, minerals and vitamins are the recognized components of the required feed. Animals need nutrients from feed in order to be strong and healthy. If some nutrients are missing livestock become weak and are more likely to contract disease; they grow less and produce less, and may not become pregnant. Livestock also need minerals for strong bones and joints and proteins to build muscles. They need carbohydrates and fat for energy, and vitamins and minerals to maintain body functions. For livestock, most of these basic feed requirements are provided by plants.

A simple classification of livestock feed groups it into roughage, concentrate and feed supplements. These and some definitions are listed below:

Roughage:	Roughages are bulky feeds that are low in weight per unit volume with a high fibre content (> 18 % crude fibre), and are low in energy (total digestible nutrients). They includes straws, stovers (crop-residues) grasses, green and dry fodder, hays, silage, tree leaves, etc. Roughages are two kinds: leguminous and non-leguminous
	Leguminous roughages: Berseem, lucerne, guar, lobia, stylo, etc. Non-leguminous roughages: Sorghum, maize, bajara, oat, rice straw, wheat straw, grasses, etc.
Fodder:	Defined as green or cured plants such as, maize and sorghum, browse as small stems, leaves, flowers and fruits of shrubs, trees or woody vines.
Forage:	Defined as aerial plant material, primarily grasses and legumes, containing more than 18 per cent crude fibre on a dry matter basis.
Concentrates:	Concentrate feeds are high in energy and low in fibre (<18%). They usually contain less than 20 % protein and more total digestible nutrients, e.g. grains, brans, cakes, etc.
	Grains: cereals, millets and legumes By-products: wheat bran, rice bran, gram chuni, rice husks, etc Oil cakes: cotton seed cake, copra cake, groundnut cake, mustard cake, linseed cake, etc.
Feed Supplements:	These are feeds that are used to supplements some particular nutrients like proteins, minerals, or vitamins. They may be available in the form of powder to be offered combined with concentrate.
Mineral Supplement:	A rich source of one or more mineral elements.
Protein Supplement:	A feed or mixture of feeds containing 20% or more protein. Examples in commercial feeds include soybean meal, canola meal.
Animal Products:	Fish-meal, bone-meal, blood-meal, meat-meal, etc. Whilst the use of animal products can increase nutrient intake, particularly of protein, they are increasingly subject to legislation that either bans or limits their use due to potential livestock and human health concerns. It must be remembered that grazing animals are not adapted to eat animal protein.
Vitamins:	Organic compounds that function as parts of enzyme systems and which are essential for many metabolic functions.
Fat Soluble Vitamins :	These include vitamins A, D, E and K. Vitamins A, D and E are supplemented in many commercial livestock rations. Fat soluble vitamins are stored in fat reserves in the body.
Water Soluble Vitamins:	These include the B complex of vitamins and vitamin C. They are not not normally supplemented for ruminants after two months of age because rumen microbes are able to manufacture enough to meet the animal's requirements. There may be a need for supplementation under two months if there is inadequate access to the mother's milk.

The Need for an Integrated Approach

Understanding the nutritional needs of livestock requires an appreciation of a number of principal issues:

Purpose	The purpose for which that animal is kept, either subsistence/survival or production and sale, and the related systems of livestock husbandry that animals are currently reared under, including aspects of 'housing', feeding and health;
Climate and Environment	The climatic environment in which the animals and livestock keepers finds themselves — humid/hot/dry/stressful or more within the tolerable parameters of the animals concerned;
Feed	The ease of access to feed/fodder — its quality and seasonal availability to the animals;
Disease	Related challenges from disease and disease vectors;
Economy	The economic situation of the livestock keepers themselves and communities they live in, as well as their access to potential credit, support systems, transport and infrastructure, to local and national markets, and ultimately to export;
Education	The education and experience of the livestock owner or keeper, and the wider experience or levels of support within their communities. This also includes the willingness to change or take risks.

Calculations based on the theoretical requirements or needs of livestock are usually based on optimal needs for production, i.e. maximum productivity. Such situations are rarely achieved under subsistence agriculture situations, or with "subsistence plus" and smallholder farmers, where the challenge is usually to maintain a greater level of livestock survival under challenging conditions. Intensive systems of production on the other hand normally require external systems of support - bringing in feed from elsewhere - in order to satisfy optimal productivity if profits are to be made.

An understanding of the basics of the dietary requirements of different livestock is an important first step in improving livestock nutrition and increasing productivity. Forage quality and nutrient content varies with plant species, variety, physiological maturity, regrowth, season, time of harvest, cutting height, fertilization (or lack of) and other factors. Under natural situations, where livestock have a free selection of forage, animals are able to make choices between a range of available foods, depending on the supply and demand of vital nutrients. The majority of smallstock will, however, be restricted in their choice of available feed by a range of factors including the farming systems, climate, seasonality, and livestock management choices.

The groups of nutrients that are essential in smallstock nutrition are:

	Water
	Energy
	Protein
	Minerals
	Vitamins

Water is normally considered to be the cheapest feed ingredient. However, production, growth , health and the overall performance of the animal will be affected if insufficient water is available. In ruminants, water needs vary with the stage of production, being highest during early lactation, and during periods when the weather is warm and the available forage is dry. When grazing forages soaked with rain water, or when consuming lush, green vegetation, many smallstock can get much of the water they need out of the feed. However, water is almost always needed and because it is difficult to predict water needs with any accuracy, smallstock should always have access to sufficient high quality water.

Ruminants

Energy is required in larger amounts than any other nutrient except water, and is often the limiting factor in livestock production. Energy comes primarily from carbohydrates (sugars, starch and fibre) and fats in the diet. Bacteria that are present in the rumen of sheep and goats ferment sugars, starches fats and fibrous carbohydrates into volatile fatty acids. These acids are absorbed and used for energy. Fat is an efficient source of energy, but in ruminants should only be present in the feed in small quantities because it depresses fermentation in the rumen.

If the diet consumed by sheep and goats contains an excess of energy, that extra energy may be stored in the body as fat, mainly around certain internal organs.

Energy is the main driving force of metabolism. If energy is limiting, the protein content in the diet will be used (inefficiently) as an alternative or additional source of energy instead of being converted into body protein.

Poultry

Carbohydrates make up the largest portion of a poultry diet. They are in greatest supply in plants, usually in the form of sugars, starches or cellulose. Starch is the form in which most plants store reserves of energy, and it is the only complex carbohydrate which chickens can readily digest. Chickens do not have the enzyme systems required to digest cellulose and other complex carbohydrates, so these becomes part of the crude fiber component and are excreted. (Chicken manure can be processed to create a high quality compost). Carbohydrates are a major energy source for poultry, but only ingredients containing starch, sucrose or simple sugars are efficient energy providers. A variety of grains, for example maize or wheat, or are important sources of carbohydrates in poultry diets.

Fats are important sources of energy in commercial poultry diets because they contain more than twice as much energy as any other feed ingredient. Fat also makes up more than 40% by dry weight of the egg contents. Fats in feeds are also important for the absorption of vitamins A, D, E and K, and as a source of essential fatty acids. These essential fatty acids are responsible for membrane integrity, hormone synthesis, fertility, and hatchability.

Proteins are long complex organic compounds that are formed when amino acids are combined with each other into polymers. All proteins in the food chain originate from plants. Digestion of plant protein by the animal provides the amino acids used in the body to form animal protein. Most protein in plants is found in leaves, petioles and seeds. Not all of the protein in the feed is digestible, and the undigested proportion is excreted in the faeces. Protein is usually the most expensive component of the diet, particularly where supplements are involved.

In ruminants, protein is required both as a source of nitrogen for the rumen bacteria and to supply amino acids for protein synthesis in the animal's body. When the levels of protein are low in the diet, digestion of carbohydrates in the rumen will slow down and intake will decrease.

Inadequate levels of protein in the diet will mean that insufficient amounts of amino acids are entering the intestines from the rumen and being absorbed. This can have a negative impact on growth rate, milk production, reproduction and disease resistance. Unlike energy, an excess of protein is not stored in the body and it is therefore important to feed enough protein to cover the nutritional requirements of the animal. The actual requirements for protein vary with developmental and physiological stages and level of production.

See also the discussion of Methods of Feed Assessment for more details of proteins.

For more on Proteins and Sources of Proteins, see the FAO publication "Protein Sources for the Animal Feed Industry".

Protein: Ruminants

In ruminants, feed is fermented in the rumen, the resulting volatile fatty acids are absorbed from the rumen and omasum and provide the major part of the metabolizable energy to the animal. The products of rumen fermentation leave the rumen along with the microbial biomass and are then subjected to further digestion in the abomasum (the true stomach) and in the intestines in much the same way as in monogastric animals. Microbial protein is digested and absorbed in the small intestine and this supplies the major part of the absorbed amino acids.

The microbial protein yield is limited by the fermented energy supply, and this is governed by the intake of feed. The amino acid requirements of the animal can be met by microbial protein alone for maintenance or low levels of production. For moderate to high levels of production, the microbial amino acid supply will most likely need to be supplemented with dietary sources of protein, or "protected amino acids", that are not digested by the by microbial action in the rumen - and which are therefore available for subsequent processing and absorption by the remainder of the digestive system.

Protein: Monogastric Animals

Protein nutrition in non-ruminants, or monogastric animals, differs from that of ruminants in that there are no amino acids being produced by microbial action.

Monogastric animals do not have a requirement for protein as such but specifically for those amino acids which the body cannot synthesize together with a source of amino acids which can be used for the synthesis of the remaining amino acids. The amino acids that cannot be synthesized must therefore be provided by the different proteins in the diet. In order to insure that the amino acid needs are met, the animals will need to be supplied with a variety of different feedstuffs that are good protein sources.

Protein: Poultry

The contents of an egg are about 50% protein, so hens that are laying will require a source of protein that is sufficient to supply the birds needs as well as the requirements for laying. Multiple feed ingredients are necessary because no single ingredient is an adequate source of all the required amino acids. Common protein sources for poultry feeds are animal proteins such as fish meal and meat and bone meal, and plant proteins such as soybean meal and corn meal.

This nutrient class is divided into the macrominerals (those needed in relatively large amounts) and the micro- or trace minerals. Both are important in the diet.

Many minerals are required by small ruminants. The minerals that animals need most are phosphorous, calcium and magnesium. They also need small amounts of other minerals, including: iron, iodine, cobalt and copper. Birds that lay eggs need large amounts of calcium. Plants get the minerals from the soil - but plants growing in soils that are deficient in minerals also lack them. Mineral supplements are usually required, especially for young animals growing fast, for pregnant animals and for those producing milk.

Grains are low in minerals, so for example, all commercial poultry feeds need to contain supplemental sources.

For more information on dietary requirements for minerals

Ruminants

Vitamins are needed by the body in small quantities. Small ruminants require vitamins A, D and E and these are most likely to be deficient in the diet. A healthy, functioning rumen population will make enough of these vitamins to meet their own requirements as well as the animal's needs, provided all other nutrients are adequate. In ruminants, vitamins B and K are normally formed by the rumen bacteria and are not considered essential in the diet. Synthesis of these vitamins is therefore related to the size and health of the microbial population in the rumen. Vitamin C can be synthesized in the body tissues in adequate quantities to meet most requirements.

Vitamin A is not contained in forages, but carotene found in green, leafy forages is converted into vitamin A by the body. In addition, vitamin A is stored in the liver and fat of ruminants during times when intake exceeds requirements. Dry, weathered forage or forages that have been stored for a long time will be deficient in carotene and smallstock fed on these materials for extended periods may require supplements.

Vitamin D may become deficient in animals raised in confinement. Animals should have frequent access to sunlight because it causes vitamin D to be synthesized under their skin. The alternative is a source of supplemental vitamin D. A deficiency in vitamin D results in poor calcium absorption. This may cause rickets, a condition where the bones and joints of young animals grow abnormally.

Poultry

The 13 vitamins required by poultry are usually classified as fat-soluble or water-soluble. The fat-soluble group includes vitamins A, D, E and K. The water-soluble vitamins are thiamin, riboflavin, nicotinic acid, folic acid, biotin, pantothenic acid, pyridoxine, vitamin B₁₂ and choline. All these vitamins are essential for life and they must be provided in proper amounts for chickens to grow and reproduce. The egg normally contains sufficient vitamins to supply the needs of the developing embryo. For this reason, eggs are a good animal source of vitamins for the human diet.

Vitamin A is needed for the health and proper functioning of the skin and lining of the digestive, reproductive and respiratory tracts. Vitamin D has an important role in bone formation and the metabolism of calcium and phosphorus. The B vitamins are involved in energy metabolism and the metabolism of many other nutrients.

For more information on dietary requirements for vitamins

Different stages of growth, production and reproduction have different nutrient requirements. Generally the highest nutrient requirements are during lactation. The lowest nutrient requirements are during mid to late gestation of the mature female. Growing animals and producing animals have different needs to those of animals that are simply meeting their maintenance requirements. To be profitable in livestock production these different dietary requirements requirements need to be met as inexpensively as possible.

However nutritious the feed offered to an animal is, it is of no use if the animal does not eat it. A number of factors affect the amount that an animal eats, and include:

• The composition of the diet
• The way feed is presented
• The individual animal and the flock or herd in which it is kept
• The availability of water

Any animal needs to have all of its nutrient requirements and other aspects of a ration satisfied. Freely ranging ruminants and poultry will tend to select different items of diet according to their requirements. Where livestock are not free to range, either for part of the time or for all of the time - as for example in intensive poultry production - care must be taken to ensure that all of the animal's requirements are provided in the feed supplied. Commercial feed is often supplied in pelleted form, and should be carefully formulated according to the dietary needs of the intended livestock species.

Feed formulation requires a knowledge of on the one hand, the nutritional requirements of the relevant livestock, and on the other hand the nutrient composition of the different items of feed that are added to the diet. Laboratory analysis is therefore an important part of this process. Animal feeds that are deficient in one or more nutrients will inevitably result in problems. Similarly, feeds that contain too much of certain ingredients may also result in problems. For example, poultry that are fed too much protein are unable to utilise it and the process of converting it to urea for excretion requires energy and can lead to reduced productivity. Overfeeding of protein may also lead to high levels of ammonia and nitrogen pollution.

Different feedstuffs contain different amounts of different nutrients, and have different properties. Nutrient composition may also vary at different times of the year, or seasonally. Also, all feedstuffs have a price. The goal of optimising a ration is to find the mix of feeds that both is the cheapest and at the same time satisfies all the animal's requirements of nutrients and other aspects of the ration.

As feed cost is the key factor in determining the profitability of intensive livestock produciton systems such as poultry farming (and especially fish farming) both feed manufacturers and farmers attempt to produce least cost rations by including products, depending on their cost, availability and nutritive value. As an example, Balakrishnan (in Protein Sources for the Animal Feed Industry, FAO 2004) lists the following sources for raw materials availabel for the poultry feed industry in India:

• forest produce (babul seed, rubber seed, tamarind seed, salseed, etc.);
• food industry waste (biscuit waste, coco shell, bread waste, powder, cocoa beans, macaroni waste, skim milk powder, etc.);
• gum and starch industry (guar meal, tapioca, tapioca spent pulp, etc.);
• fruit and vegetable processing waste (citrus wastes, mango waste, tomato pomace, pineapple waste, tea leaves, etc.);
• alcohol industry waste (yeast sludge, grape extractions, breweries’ dried grain, etc.).

Feed formulation software has been developed to assist with the process of optimising the nutrient content of feed. The overall concept is relatively simple if the nutrient content of each of the different ingredients is known and the requirements of the animal are known. The software assists in determining the ideal list of ingredients and the quantities of each. If the cost of different ingredients is also known then the process is used to determine the least-cost approach.

One example of software used for feed formulation is UNEform, which is an Excel workbook for feed-formulation by linear programming or by manual manipulation developed by the Poultry Research and Teaching Unit of the University of New England in Australia. It is set up with some basic requirement parameters for poultry and pigs, and has a basic ingredient matrix. Any competent Excel user can add requirement parameters and ingredients. The software can be downloaded from the UNEform web download site, whilst further information is available at a SARDI web page on poultry requirements and feed formulation .

See also: Small-scale Manufacture of Compound Animal Feed

Alabama Cooperative Extension System. (1994), Nutrient Requirements of Sheep and Goats.
Used by permission of the Alabama Cooperative Extension System (Alabama A&M and Auburn Universities) and the author, Dr. Diego Gimenez, Associate Professor, Animal Sciences, Auburn University.