Poultry Feeds and Feeding

Poultry Husbandry Chapter II: Poultry Feeds and Feeding

1. Definitions And Terms Used.

Nutrition. The process of digesting, absorbing and converting food into tissue and energy. Also, the study of this process.

Nutrient. A substance that can be used as food. Some people use "food" for nutrients eaten by people and "feed" or "feedstuff" for animals.

Digestion. The process of changing food to a form that can be absorbed from the digestive tract by the body tissues (mainly the intestines). In the digestive tract this is done by enzymes and other material produced by the digestive tract which break down the food into small, simple (molecular) components.

Digestion by microorganisms. Some bacteria and protozoa produce enzymes and other material that break down cellulose, and fibre etc. that non-herbivores (non-grass eaters) like chickens cannot digest. There is some digestion by microorganisms in the cecum of chickens. Enzymes produced by bacteria can be added to some feeds to improve digestion and absorption.

Metabolism. A chemical reaction that takes place in the tissues and organs of the body in which the food that has been digested and absorbed is changed either into energy or building blocks for the body. Energy is the power produced by the food. It is the fuel, like petrol for cars, on which the body runs and, like burning wood or petrol, metabolism requires oxygen and produces heat and waste material (carbon dioxide and water).

Basal metabolism, basal metabolic rate (BMR). The amount of energy (fuel) required to keep the body alive and operating without activity, growth or production.

Energy. Energy is the amount of power produced when food is metabolized. Energy is measured in heat units (calories or joules). In nutrition the kilocalorie (kcal) equals 1000 gram calories. A gram calorie is the heat required to raise 1 gram of water 1BC (14.5 to 15.5BC) (1 kcal equals 4.184 kjoules).

Metabolizable energy (ME). The amount of energy available to be used for maintenance, for production of body tissue (for growth and replacement), activity and egg production, when a food material or feed is eaten. It includes the heat lost during metabolism. The ME of a feed ingredient (individual feed) may be used to indicate the nutritional value of that ingredient. Feed ingredients or feeds are rated as high or low energy. ME depends on the quality of the feed and on the % dry matter. Good maize (corn) at 85% dry matter (15% water) has an ME of 3300 kcal/kg. The ME for barley is 2700 kcal/kg. Fats may have an ME of 9000 kcal/kg. If chickens are fed a low energy feed they will eat more feed, if it is available, to get the required energy. In monogastric animals, like chickens, energy comes mainly from carbohydrates and fats since fibre containing cellulose cannot be digested.

Organic. Organic compounds are defined in nutrition as animal or plant material containing carbon.

Carbohydrates. Carbohydrates are organic compounds and a source of energy for poultry. Simple carbohydrates are made up from sugars: glucose from maize is a monosaccharide. Lactose from milk, sucrose from sugarcane or sugar beets and in smaller amounts in many plants, particularly in their fruits, seeds or roots are disaccharides. Complex carbohydrates (polysaccharides) are made up from combinations of sugars. Some, like starch (from cassava, maize, wheat, etc.) can be digested by chickens while others (cellulose, a structural carbohydrate) cannot because animals do not have the enzymes to break down (hydrolyse) cellulose so that it can be absorbed. This digestion is done by bacteria and protozoa in herbavores.

Fats (oils, lipids). Fats are a source of energy and in some cases fat soluble vitamins. Like carbohydrates, they are organic compounds made up from carbon, hydrogen and oxygen which form fatty acids. Because they are higher in hydrogen and lower in oxygen than carbohydrates, fats have a higher energy value (ME) than carbohydrates. Fats that are high in unsaturated fatty acid are liquid at room temperature and are called oils. Vegetable oils (canola oil, corn oil, cottonseed oil, soybean oil, etc.). Most essential fatty acids (required for health & growth) can be produced by the chicken from other food; but linoleic acid must be present in the diet of chickens for proper growth and egg production.

Proteins. Proteins are organic compounds used to build the cells, tissues and organs for the body. They are made up from many amino acids some of which are essential for growth and production. Proteins contain about 16% nitrogen so the amount of protein (crude protein, not the digestible or usable protein) in a feed can be estimated by measuring the nitrogen content. Excess protein (above what is required for growth or production) is used as energy and the nitrogen excreted in the urine. During digestion protein is broken down into individual amino acids for absorption. In the body these are reassembled to make body tissue or egg protein. Birds can make some amino acids from other protein but many amino acids are essential, that is they must be present in the diet. Proteins from animal sources (meat, milk, insects, larvae etc.) contain the essential amino acids. Most plants are low in protein and vary widely in essential amino acid content. Most are low in one or more essential amino acids. Some legume plant seeds such as beans are high in protein.

Vitamins. This term describes a variety of essential nutrients that are not similar to one another, except that they are essential in the diet, but only required in very small amounts. They are used as metabolic regulators. They are either water soluble or fat soluble. Vitamins or their precursors are present in small, but variable amounts in some feeds. Most vitamins are manufactured (synthetic) for use in commercial feed. Precursors of vitamin D3 can be produced in the skin by sunlight. Vitamin C is produced by bacteria in the intestine in chickens.

Minerals. Minerals are not organic. They are chemical elements. Those required in small but significant amounts (calcium, phosphorus, sodium, potassium, magnesium and chlorine) are major minerals. Essential trace minerals are iodine, cobalt (as cobolamin), iron, copper, zinc, selenium and molybdenum. Most minerals must be added to the diet for good growth and egg production. Laying hens need a ration with 3% calcium to make egg shells. This can be supplied free choice as small pieces of bone-meal, coral, sea-shell or limestone. Phosphorus in plants is present as phytate phosphorus and is only partially available unless phytase enzyme is added to the feed.

Water. Water is an essential nutrient. Water is the major part of animal tissues and all body functions require water.

A source of clean, cool water should always be available free choice.

Antibiotics. Antibiotics are drugs made from bacteria or fungi that are used as medicine to prevent or treat bacterial disease. They are sometimes used as growth stimulants in chickens.

Probiotics. Probiotics are bacteria or products produced by bacteria that encourage the growth of "good" bacteria (those that prevent the attachment and or growth of disease causing bacteria) in the intestine.

Chemotherapeutics are chemical compounds used as medicines.

Vaccines are preparations of live organisms, (mainly viruses) used to produce immunity (defence) against disease causing viruses. They stimulate antibody production by the chicken to protect against the virus material in the vaccine. Because they are live and must multiply in the body to be effective, they can be used as a spray, in water, eyedrop, wing web injection or subcutaneous injection.

Bacterins are preparations of killed organisms (bacteria, mycoplasma, virus, etc.) for subcutaneous or intramuscular injection. They also stimulate antibody production.

Antibodies are very small particles produced by lymphocytes (type of blood cell) that circulate in the blood to help the body defence systems stop infection by specific virus or bacteria that had stimulated the lymphocytes to produce the antibody. They can also be passed in the egg from the hen to the chick (maternal antibody) and protect the chick for 1-3 weeks.

Cereal grains. Cereals are the grains grown specifically from human and animal food. They include wheat, millet, rice, maize (corn), sorghum (milo, kafir or guinea corn), barley, oats etc. Grains provide the main source of energy in commercial poultry feed. Protein in cereals are low (8 to 12%) and the quality (level of essential amino acids) is poor.

By-products. By-products are the parts of a grain, oilseed, or animal that is being prepared for human food, that is not used for human food. Examples are wheat or rice bran or animal viscerae that may be fed to chickens.

Complete feed. A prepared feed that contains all of the nutrients for the best growth or egg production for the flock for which it is being used is called a complete feed. These feeds are usually prepared commercially by a feed manufacturer. Broiler chickens receive high protein (21 to 23%) starter for the first 14 to 21 days, grower to day 28 or longer and finisher, that is lower in protein and higher in energy, until ready for market.

Supplement or concentrate is a prepared feed that is intended to be added to or mixed with other feed material to improve the nutrient balance of the final feed.

Premix. A premix may contain a variety of specific ingredients such as vitamins, trace minerals, amino acids, or medicine that is to be mixed with other feed to supply essential or important elements that may be missing. Essential nutrients are sometimes added to the water if they are water-soluble.

Antinutrients. Some feed ingredients and potential feeds contain factors that inhibit the digestive process causing reduced growth, diarrhea or pasting. They limit the amount of some feed ingredients that can be added to the final feed. The antinutrition factors in some feed material such as beans can be destroyed by heat (cooking).

Phytotoxins are toxic or poison substances found in plants used as feed for chickens. The toxic material can be in the seed (castor bean) leaf or stem or in the root or tuber (cassava). At low levels some might only reduce growth rate or have no effect. At higher doses they might cause illness or death. Toxic weed seeds may contaminate grain that is being harvested making that feed toxic.

Mycotoxins are poisons produced by moulds growing in food material. Various fungi produce different toxins. Aspergillus fungi produce aflatoxin, one of the most serious in hot climates. The fungi can grow in crops in the field, in seeds in storage or in prepared feed for chickens.

2. Nutritional Requirements Of Poultry

Poultry require carbohydrates, fats, protein, vitamins, minerals, and water. Most nutrients provide both energy (as carbohydrate or fat) and protein. Feedstuffs are usually classed as being primarily a source of energy or protein. Fats and oils do not provide protein. Energy and protein are more efficient if they are available in the proper ratio. Excess protein is used as energy with increased waste excretion. Growing chickens should have 16-24% protein; growing turkeys, 24-28% protein; for egg production 15-17% protein; for maintenance (no growth or production) 10-12% protein. The highest requirement is in the first 2 to 3 weeks and is higher in young leghorns than broilers. The protein level can be lower if the essential amino acids are all present at the proper level. The vitamin and mineral levels are higher for growing birds and for egg production. More rapid growth requires more added vitamins and minerals than slow growth. In slow growing birds more of some of these essential vitamins and minerals are available from the feed ingredients because the amount of feed required for basal metabolism is greater.

Some feed and water is required just for survival. The BMR varies directly with the weight of the bird. If the feed energy required to supply the basic energy need is not available, the bird will lose weight, get thin and die. Some protein, fat, vitamins and minerals are also required for basic survival. Nutrients available above the basic level can be used for growth in young birds and egg production in adults. Excess energy is converted to fat and stored in the body. It may be used when energy from feed is lacking as in the hump in camels and tail fat in fat-tailed sheep.

The rate of growth in young birds or egg production in adults is controlled by:

a) the genetic potential (commercial broilers compared to layers)

b) the amount of energy and protein (and protein quality) available above the level for the BMR. The feed required to maintain BMR does not add to growth or production. The maintenance requirement for a slow-growing broiler is the same as a fast-growing broiler of the same weight. The feed maintenance requirement for a hen laying 2 eggs a week is the same as a hen of the same weight laying 6 eggs a week. Sufficient vitamins and minerals must also be available.

If the temperature is below the birds comfort level, additional energy is required to provide internal heat by increased metabolism to maintain body temperature. Activity also increases metabolism and birds that are allowed to run outside or that scavenge for their feed have a higher requirement for energy.

Chickens that get all their nutrients from scavenging may eat an excess of protein, if insects, worms, larvae etc. are available. They might benefit most from supplemental feeding of energy in the form of carbohydrate (cereal grains etc.). Fenced or backyard poultry fed household or garden waste may lack both energy and protein for good growth or egg production. Laying hens should have calcium available free-choice, even if calcium is being added to feed. Chickens that eat whole seeds, grains, vegetable material or fibre must have insoluble grit (granite grit) or small stones in their gizzard to grind the hard or fibre material. Birds that forage pick up their own grit. Poultry kept indoors must have grit supplied. Small chicks require small stones 2 to 4 mm. Hens .5 to 1.5 cm. Limestone particles are not satisfactory as grit.

The amino acids that growing poultry require are: arganine, cystine, lysine, methionine, tryptophan, histidine, isoleucine, leucine, phenylalanine, threonine, tyrosine, valine.

The following vitamins should be added to a prepared feed: vitamins A, D3, B12, riboflavin, pantothenic acid, niacin, folicin (folic acid), thiamine and biotin.

3. Commercial Nutrient Sources.

In countries where complete feeds are prepared by feed manufacturers, cereal grains and oilseed meal are the major ingredients in the feed. Depending on cost, availability and age or type of poultry or water fowl, some of the following products are also frequently used: by-products of cereal grains processed for human use, animal processing waste, fishmeal, waste oil from restaurants (restaurant grease), yeast, alfalfa meal, distillery or milk factory products etc. Vitamins and mineral are also added in the correct proportions. The ingredients are ground (if required), mixed and may be pelleted.

Ingredients most frequently used:

for energy: maize (corn) up to 65%

sorghum (milo) up to 45%

wheat up to 25%; with enzyme up to 45%

wheat by-products (bran, shorts, screenings) up to 15%

rice up to 15%, rice by-products (bran, polishings) up to 15%

barley up to 15%; with enzyme up to 35%

molasses, up to 5% after 2 weeks

for protein: soybean meal up to 30%

soybeans up to 15% (heated to remove antinutrients)

canola meal or whole seed up to 10%

corn gluten up to 15%

peas, lupin, flax up to 10%; flax (linseed) meal - 15 % (20% in layers)

safflower meal, sunflower meal up to 10%

meat meal, fish meal up to 10%

blood meal, feather meal up to 2%

Fats and Oils: tallow, lard, coconut oil, palm oil, after 3 weeks up to 5%

poultry fat, fish oil, restaurant grease up to 3%, after 3 weeks 6%

Minerals: Calcium can be added as limestone, as prepared products such as dicalcium phosphate or as oyster or other marine shell. Growing birds require about 0.9% calcium in the diet. Hens in lay require 3 to 4% calcium in the diet so that calcium is available for egg shell production.

Phosphorus can be added from manufactured products such as dicalcium or monocalcium phosphate. Phytate phosphorus (an organic phosphorus) is present in small but varying amounts in plants feed ingredients. This phytate phosphorus is only 25-50% available unless phytase enzyme is added to the ration. Growing birds require about 0.4% phosphorus, adults about 0.3%. Calcium and phosphorus levels must be in balance since high levels of one cause deficiency of the other.

Sodium and chlorine are usually added as salt (NaCl) at about 0.25% of the ration (2.5 kg NaCl/1000 kg).

Magnesium and potassium are usually present in adequate amounts in the feed ingredients. Some ingredients such as soymeal and molasses are high in potassium. Minerals may be present in high or moderate levels in animal by-products. If animal by-products are being fed the minerals present in this feed should be used in the calculation of the amount to be added. High levels of sodium are toxic to birds. Saline water is also toxic for birds.

Trace minerals and vitamins are required in small quantities. They are not usually added as separate ingredients. They are usually bought as a prepared package or a premix. A specified amount of this premix can then be added to each tonne (1000 kg) of feed. To make sure of an even distribution in the final feed the vitamin-mineral premix may be mixed with 25-50 kg of cornmeal or other large particle ingredient that will help ensure an even mix. This is then added to the larger mixer after the cereal and protein portions have been put in. The calcium, phosphorus and salt should never be added to the vitamin premix. The mixer should be grounded.

4. Alternative Feeds

There are many vegetable and animal products that can be used as feed ingredients for poultry. Poultry cannot digest fibre found in roughage, seeds, grains and fruits. Products that are high in fibre can make up only a small percent of the feed. Since many plant products also contain antinutrients the amount of these feed stuffs that can be fed is also limited. Products that contain a high percent of water (kitchen and garden waste, weeds, tree and plant leaves, fruit, worms, larvae, fresh fish and animal waste, water animals and insects, milk products etc.) can be given free-choice. What is not eaten must be removed so the chickens will not eat mouldy or spoiled material. Most feeds can be sun-dried to reduce the water content. They can then be ground into meal to be mixed with other feed, or cut up into chips that the birds can eat.

Possible Alternate Feeds for Poultry

CP = approximate % crude protein

 

 

Name

Maximum Recommended

Toxins/Antinutrients

a) Energy sources

I. grains

millet meal (or whole grain)

oats

barley

rye

wheat

triticale

sago meal

 

30%

5% - dehulled 30%

10% - with enzyme 30%

5% - with enzyme 20%

20% - with enzyme 40% (10% CP)

5% - with enzyme 20% (12% CP)

15%

 

 

 

B-glucans

tannins

tannins

Cereal by-products

corn gluten feed

wheat bran

wheat middlings

rice bran or polishings

30% (22% CP)

5% (15% CP)

10% (17% CP)

15% (13% CP)

 

II. Roots, corms and tubers

Soaking in water for 60 min. or cooking before drying will remove some antinutrients from roots, corms and tubers.

cassava root meal, (farine, tapioca);Manihot esculenta

malanga (taro) cormmeal;

15% with 0.1% methionine and 0.2% sodium sulphate (Na2SO4) 30% (2% CP)

10% (6.5% CP)

cyanide, polyphenols and antinutrients

antinutrients

Colacasia esculenta

dried factory sugar cane waste or molasses

yam meal; Canna edulis

yucca meal; Yucca amaraga

sweet potato meal; Ipomea batatas

potato; solaum tuberosum

5% after 2 weeks 10% after 4 weeks

10% (fresh, free choice)

10% (fresh, free choice)

30% (fresh, free choice)

20% (7% CP)

 

 

 

 

 

trypsin inhibitors; solanine, if green or spoiled

III. Other feeds

plantain & banana meal or sun dried chips

plantain & banana peel meal

breadfruit meal or sun dried

breadfruit leaf meal

nettle meal

cocoa husk meal

sweet potato peel meal

dried factory tomato residue

dried factory potato waste

dried factory citrus residue

dried factory date waste (without stones)

20% (fresh, free choice)

5% (fresh, free choice)

10% (fresh, free choice)

2% (fresh, free choice)

5% (fresh, free choice)

5% - 10% after 8 weeks

10% - 20% layers

5%

5%

5%

5% (4% CP)

 

 

 

 

 

 

 

 

 

trypsin inhibitors

Name

Maximum Recommended

Toxins/Antinutrients

b) Protein sources

I. Grain legumes

Legume plants and seeds (grains) are higher in protein than other plants. Many grain legumes contain antinutrients such as trypsin inhibitors, tannins, saponins, alkaloids, and antivitamins that can be removed by heating or processing. Over-heating also lowers the nutritional value.

field peas; Pisum sativum

cow peas; Vinga unguicalata

pigeon peas; Canjanus canjan

chick peas; Cicer arietinum

sweet lupin; Lupinus albus

vetch; Lathyrus species

(L. odoratus, sweet pea; L. hirsutis, caley pea; L. pusillusL. roseus)

vetch; Vicia species

jack beans; Caravalia ensifornis

faba (field) beans; Vicia faba

narbon beans; Vicia nabonenis

kidney bean; Phaseolus vulgaris

lima beans; Phaseolus lunatus

soybeans; Glycine max

peanuts, Arachis hypogaea

10%

10%

5%

5%

5% - 15% in layers

2%

 

2%

5%- 10% in layers

5%- 10% in layers

5%- 10% in layers

5%- 10% in layers

5% - 10% in layers

10% - 15% after 3 weeks (35% CP)

10% - 15% after 3 weeks (46% CP)

antinutrients

antinutrients

antinutrients

antinutrients

antinutrients

lathyrogens & antinutrients

 

lathyrogens, cyanogenic glycocides, antinutrients

antinutrients

antinutrients

antinutrients

antinutrients

antinutrients

antinutrients

antinutrients

II. Oilseed cake (processed meal, oil removed)

soybean meal

peanut cake

coconut oil meal; copra

palm kernel meal

flax cake

sunflower meal, Helianthus annus

safflower meal

sesame seed meal

cottonseed meal; Gossypium sp.

Canola meal (and other low erucic acid rapeseeds) Brassica napus

corn gluten meal (60%)

 

40% (46% CP)

10% - 20% in layers (40% CP)

15% - 20% in layers (21% CP)

15% - 20% in layers (21% CP)

15% - 20% in layers (43% CP)

10% (40% CP)

10% (40% CP)

10% (47% CP)

5% - 10% in layers

10% - 20% in layers (33% CP)

15% (60% CP)

 

 

 

 

 

 

 

 

 

gossypol

goiterogenic factors, erucic acid, glucoisolates

III. Other protein sources

weed seeds (separated from cereal grain for human use)

coca bean meal

coffee seed meal

tamarind seed

rubber seed meal

mango seed kernel meal (dehulled)

carob tree pod meal; Ceratonia siliqus

ambadi seed meal; Hibiscus cannabinus

Jamaica seed (meal), Hibiscus sabdariffa

dried cow dung or rumen content

 

5%

5%

2%

2%

2%

5% (or fresh free-choice)

5% - 10% in layers

5% - 10% in layers

10-20% in layers (26% CP)

5% after 2 wks of age, (25% CP)

 

toxic seeds may be present

theobromine

caffeine

Tannins, antitrypsin

antinutrients

 

 

 

(18% fat)

 

 

 

Name

Maximum Recommended

Toxins/Antinutrients

dried poultry manure

alfalfa leaf meal

subabul leaf meal; Leucaena leucocephala

subabul seed meal; Leucaena Leucocephala

dried distillery or brewery waste

sweet potato leaf meal

water fern, Azolla pinnata

duck weed meal; Lemma fibba

other aquatic plants; Elodea canadensis, Hydrilla vertuallata

algae meal; Spirulina plantensis

housefly pupae or larvae meal

silk worm pupae meal

earthworm meal (or sun dried)

termite meal

amaranth; Amaranthus patulas

Sesbania macrocarpa seed meal

quinua seed (or meal),Chenopodium quinoa

5% after 2 wks of age, 10% after 4

wks of age, 15% in layers

3% (16% CP)

3%

5%

5% (22% CP)

2%

fresh 3% or free choice

10% - 25% for layers

3% - 5% for layers (30-40% CP)

5%; with 0.5% lysine and 0.2% methionine 10%

5% (or fresh) (60% CP)

5% (or fresh)

5% (or fresh) (60% CP)

5% (or fresh)

5% - 10% in layers

2% - 8% in layers

5% (12% CP)

if from layers contains up to 7% Ca and 2% P

saponins

minosine, antitrypsin

minosine, antitrypsin

 

 

 

 

 

 

some blue-green algae (Cyanophite) are toxic

 

 

 

 

 

saponins

C. Fat (lipid) and oil sources

flax, linseed

peanuts, ground nuts

sunflower seeds

sesame seeds

safflower seeds

cotton seed

palm oil

coconut oil

fresh or dried coconut meat

avocado, Persea americana

fish oils

10% (25% CP)

10% (25% CP)

10% (20% CP)

10% (10% CP)

10% (20% CP)

5% after 3 weeks

5% after 2 weeks

5% after 2 weeks

10% (14% CP)

fresh fruit 5%

3-6% after 3 weeks

 

 

 

 

gossypol

 

 

unknown toxin

D. Vitamin sources

Name

Vitamins

Comment

Fresh green leafy plants and garden waste contain carotenes which can be converted to vitamin A and contain some vitamin K, riboflavin, B6, biotin, and folacin

sweet potato

grains, oilseeds (soybean etc.)

alfalfa leaf meal

sunlight (ultraviolet irradiation)

milk & milk products

palm oil

coconut water & jelly

papaya; paw paw

fresh fish liver

yellow corn

vit. A, vit. C

vit. E, choline, biotin, folacin

vit. K, vit. E, vit. A, B6, biotin

vit. D3 (precursors)

riboflavin, pantothenic acid, pyridoxine (B6), folacin, biotin

provitamin A

vit. E

vit. A, vit. C

vit. A & D3

the pigment cryptoxanthin can be converted to vit. A.

 

 

poultry require D3

 

 

 

plus energy

plus protein

 


Name

Vitamins

Comment

Vitamin B12 (cyanocobalamin) is present only in animal products (meat, milk etc.) or products of bacterial fermentation.

Folacin (folic acid) is present in many grains and other feedstuffs.

Choline is required in larger amounts than other water soluble vitamins. It is found in animal products (fish, meat, milk), distillery and brewery by-products and soybean meal.

E. Mineral sources

Minerals are present in small but varying amounts in all feeds. They are higher in milk and animal by-products. Organic phosphates are present in cereal but are only 25 to 50% available. Some minerals are present in water, occasionally at toxic levels (particularly salt).

 

Many fresh (undried) foods such as garden and kitchen waste, fruit, plants and vines can be fed free choice. The best way to preserve foodstuffs is by sun-drying. It is important to avoid spoilage. Some types of foods can be preserved by anaerobic (no air) fermentation (making silage) where the fresh food ferments and becomes acid. The acidity prevents the growth of spoilage organisms. With plant material this may be done in a large plastic bag kept in the shade. Milk may be preserved for short periods by allowing it to sour (go acid) or by adding acid material.

Seeds and grains that contain antinutrients and toxins must be used with care since levels of antinutrients and toxins vary. Several varieties of raw or unprocessed peas and bean should not be used together (don’t use 5% of each) because they contain similar antinutrients and toxins.

Proteins are fed for the nitrogen and amino acid content. Some amino acids are essential and must be present in the feed or added as synthetic amino acids. Poultry cannot make them from other amino acids or nitrogen. Feeding a variety of protein sources may supply more of the essential amino acids.

Poultry require both sodium and chlorine. There is some sodium and chlorine in feedstuffs, but both must be added to the feed, usually as salt. The recommended level is 0.25 to 0.3% added salt (2.5 to 3 kg per tonne). If feed ingredients or drinking water contains salt, the amount of added salt must be reduced. Poultry can be poisoned by the sodium in salt and young chickens are very susceptible to high sodium. Chicks are frequently poisoned by salt in the drinking water. Water for young chicks should not contain salt and many chicks die from salt poisoning at levels below 0.1% (0.9% is the level found in animal tissue). Chicks can be poisoned by eating salted fish and particularly by the brine used to preserve fish.

Young chicks can also be poisoned by high calcium levels in the feed. Feed for layers contains 3 to 4% calcium. That level can cause kidney disease in young chicks.

5. The Importance Of Water

Water is an essential nutrient. All body functions and processes require water. Water is the material in which all other nutrients are carried in solution. The tissues and cells in the body are made up mainly of water. Water is also present between cells so that material can be moved between cells. Dry feed contains only 10-15% water and poultry need about twice as much water as feed (2 gms of water for each gm of dried feed).

Water should be clean and free from chemicals and minerals. It should not contain harmful parasites or bacteria. Water should be easily available free-choice. If water consumption is restricted, growing chickens will grow more slowly. Broilers that get only 2/3 or 1/2 of the amount of water they want will eat less feed and grow at only 3/4 of the expected rate. In cool climates water restriction is used to slow growth in breeders or to reduce the ascites syndrome. If water is not freely and easily available adults will lay fewer eggs and may suffer from kidney disease (as do people that do not consume sufficient water). Layers that go without water for a day or two will stop laying and may take 2-3 weeks to recover. Water in a trough or cup must be deep enough to allow the bird to drink properly. A depth of 2 cm is adequate, unless poor beak trimming has resulted in long lower beaks. The drinkers must be easy to reach and housed poultry must not have to walk too far to get water; not more than 2 metres for broilers and 4 meters for adults.

In hot climates water availability is even more important. The amount of water required becomes much higher as the temperature rises above 25BC. Birds cool themselves by water evaporation from their respiratory system and lose water when they mouth breath. In hot climates cool water is better than warm water. For large groups of poultry the water pipes to the poultry sheds should be 40 to 60 cm underground to cool the water as it flows to the chickens. Above ground pipes and emergency tanks should be shaded from the sun. To keep the water in emergency tanks fresh it can be used for 3 to 5 hours in the early morning. Chickens will move to cooler parts of the pen when the temperature is high, particularly if there is a breeze or fans. It is important to have water easily available in these areas because the birds may not go back to hot areas to drink.

Nipple drinkers help conserve water and avoid spillage, but chickens drink less water from nipples. Nipple drinkers require careful management. The pipes must be level, at the correct height (at eye level for chicks, just above eye level for older birds) and the water pressure must not be too high for the birds to operate the nipple. The water column that controls pressure should be about the same height as the chickens using the system (6 cm for a 6 cm chick).

Newly hatched chicks should have water before or at the same time as they receive their first feed. It must not be in an open pan or trough that the chicks can get into. Wet chicks lose body heat quickly and may die. Water jugs inverted in pans with a narrow water source are satisfactory as are raised narrow troughs, bell-type drinkers and nipple drinkers. Water jugs, troughs etc. must be cleaned at least once a day.

Water Problems

Water containing physical particles or dissolved mineral material may interfere with automatic drinkers. Particulate material and iron may be removed by a sand filter and settling tank but dissolved minerals and algae growth in the system are more difficult to control. Regular cleaning and flushing may be necessary. Copper sulfate solution may control fungi and algae growth, but it can be toxic for poultry.

Poultry may be poisoned by minerals or chemicals in the water. The sodium in saline (NaCl) water is the most frequent problem. Young birds are very susceptible to sodium toxicity. Sodium above 500 ppm (0.05%) in the drinking water may cause death in young chickens and turkeys depending on the sodium level in the feed. The young birds usually die from oedema and ascites syndrome. Wet droppings or diarrhea would also occur. Salt in the feed can be reduced to avoid disease from salt in the water up to about 1000 ppm (0.1%) of sodium in the water. Saline water above 1000 ppm should not be used for broilers up to 21 days of age even if no salt is added to the feed. High levels of sodium will kill adult chickens by causing diarrhea and dehydration.

Sodium may be present in water as sodium sulfate (NaSO4) or sodium bicarbonate (NaHCO3). Sulfate may be present as magnesium sulfate (MgSO4) and cause diarrhea and death. All sources of sodium in the feed, whether added as salt or present in the feed ingredients, (particularly animal protein) and water are additive in causing sodium toxicity. If sodium is too high in the feed it will cause disease as it does in the water. Sodium, however, is an essential nutrient and poultry require some sodium to grow and produce eggs.

Nitrate in feed and water may be toxic at high levels but can reduce growth at 50 ppm in water. A variety of other naturally occurring minerals and chemicals may be present in water and may cause problems. Surface water may be contaminated by farm pesticides, fertilizer or by industrial chemicals.

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