Feeds account for about 60 to 70 per cent of the total cost of producing eggs or meat from poultry.
Of the total feed cost, about 95 per cent is used to meet energy and protein requirements, 3 per cent for major mineral, trace mineral and vitamin requirements, and 2 per cent for various feed additives.
The ingredients should be selected based on the nutrients they can provide, the absence of anti-nutritional or toxic factors, their palatability or effect on voluntary feed intake, and cost. It is also important to know which feed ingredients are needed and how they should be used in poultry diets.
These diets are formulated from a mixture of ingredients, which are assembled on a least-cost basis, taking into consideration their nutrient contents as well as their unit prices.
Cereal grains: They contribute greatly in meeting the energy requirements of birds. Their quality depends on seasonal and storage conditions. Poor growing or storage conditions can lead to grains with a lower than expected energy content or contamination with mycotoxins or toxin-producing organisms.
Environmental factors also affect the nutrient content in grains and the digestibility of nutrients contained in an ingredient. Although the amounts and types of cereal grains included in poultry diets will depend largely on their current costs relative to their nutritive values, care must be taken to avoid making large changes to the cereal component of diets, as sudden changes can cause digestive upsets that may reduce productivity and pre-dispose the birds to diseases.
Maize is an excellent feed ingredient for both meat and egg laying birds and is extensively used as an energy source. It is high in energy but low in protein.
The available protein in maize is of poor quality because it is deficient in both tryptophan and lysine, hence the need to provide supplemental amino acids.
Most hybrid varieties tend to produce grain of lower protein content than the old open-pollinated varieties. Yellow maize has higher protein content and contains yellow pigmentation that helps in producing yellow egg yolks and yellow-fleshed broilers.
The other energy source that meets most of the same criteria as maize is low-tannin sorghum. Sorghum can be grown in low-rainfall areas and is a popular crop in hot, drought-prone regions.
The high tannin content of many older sorghum varieties limits their use in poultry diets, but low tannin varieties are now available and can be used in poultry diets without any limitation. The energy value of low-tannin sorghum is 90 to 95 per cent that of maize.
Millet also resembles maize in energy content but has considerably higher protein content.
When milled, it is an excellent constituent in poultry diets, with similar feeding value to barley and it promotes the production of white fat.
However, the cereal is prone to infection by fungus in the dry season, which can produce toxins that are dangerous to both human and poultry.
Wheat is also an energy source with a slightly lower energy content than maize but higher in protein content.
Wheat is very glutinous and if fed in a ground condition, it should be limited to 30 per cent of the diet. Higher levels are possible if the wheat is fed whole.
Barley, on the other hand, has a protein content of 10 per cent and a fibre content of seven per cent in grain form, which makes it an unsuitable ingredient for inclusion in diets for highly productive laying birds and broilers, especially under hot climate conditions.
However, using hydroponics to produce barley improves the nutritive value by increasing the protein content to 16 per cent with lower fibre content of 1 percent. Barley in grain form could, however, be used in broiler breeders where the desire is to reduce feed intake.
Rice is a valuable ingredient since it is high in starch and low in oil but the threshed one has a thick, fibrous husk that contains 20 per cent silica and in this form, it can cause adverse effects on poultry performance.
Cereal by-products: These are typically high in fibre, which is poorly utilised in poultry and is low in energy. Manufacturers of maize meal usually produce maize by-product called ‘hominy chop’ that comprises of maize bran, maize germ and parts of the seeds. It is slightly lower in energy than whole maize but it is higher in protein and fibre content.
Maize bran, on the other hand, consists of the outer coating of the maize seeds. It contains 15 per cent fibre and is low in energy. It is not a suitable ingredient for inclusion in the diet of high-producing broilers and layers.
Wheat bran consists almost entirely of the coarse outer coating of the wheat seed. It contains about 10 per cent fibre, which limits its value for poultry feeds, but the protein of the bran is of better quality than that of wheat or maize. It is rich in phosphorus, which is one of the highest of all common feed ingredients.
Rice bran is a by-product of rice and is high in fibre and oil. If poorly stored, the high oil content is likely to make it go bad. It probably should not be added in poultry diets at levels above 20 per cent of the total ration.
Wheat pollard consists of fine wheat bran mixed in varying proportions with wheat meal. A good quality pollard should consist of 50 per cent bran and 50 per cent wheat meal. It is appreciably more digestible than wheat bran and has lower fibre content and relatively high protein content of 14-16 per cent.
Brewers dried grains is normally a by-product of barley but those from sorghum have a similar composition. The protein content is about 20 per cent and the fibre content 14 per cent. The high fibre content means that they are of limited value to poultry.
Molasses is also considered an energy source, however, it is unsuitable for poultry but can be used in limited levels of not more than 2 per cent of the diet because it causes diarrhoea and wet droppings and sticks to birds’ feathers.
Roots and tubers: These are not recommended as an ingredient in poultry diets because of the low dry matter and the presence of glucosides. Ensure that the tubers are chopped into thin slices and left in the sun to dry to reduce the moisture content from 65 per cent to 14 per cent, as well as they release cyanide, reducing it to acceptable levels.
The dried tubers can then be milled and introduced to poultry diets. However, they have low protein content and a balance of amino acids very different to that required by poultry.
Plant protein: These sources usually come as meal or cake, the by-product of oilseed crops. After the oil is extracted, the remaining residue is used as feed ingredient. Oilseed meals make up 20-25 per cent of a poultry diet.
Soybean is the most suitable plant protein source for poultry diets because relative to other oil seed meals, the protein content has a good balance of essential amino acids, which can complement most cereal-based diets.
Raw soybeans contain several anti-nutritional factors, including protein inhibitors, which can negatively affect digestion and the bird’s performance.
However, these inhibitors are destroyed by heat during the extraction of oil from the seeds.
Groundnut meal obtained from de-husked groundnut is suitable as a poultry feed because of its low fibre content.
The quality of protein of groundnut meal is good, ranking close to that of soya bean meal. Its major disadvantage is that the meal is often contaminated with aflatoxins.
Cottonseed meal is rarely used in poultry diets because of gossypol substance, which is poisonous to birds as it may cause anaemia, diarrhoea and eventually paralysis.
Proper processing of cottonseed during oil extraction ensures the heat changes the gossypol to ‘bound gossypol’, which is less poisonous.
A good quality cottonseed meal is light yellow and has a sharp nutty smell. A dark colour indicates that it contains a high percentage of shells and fibre.
Ensure you limit the inclusion of cottonseed meal in poultry diets to 10 per cent. If the ration of layers has more than about 5 per cent cottonseed meal, the yolks of the eggs develop an olive green or brown colour, which tends to affect egg quality.
In addition, the cottonseed meal should be limited to 2 per cent in the diet of the breeding flock since the gossypol substance can adversely affect the hatchability of fertilised eggs.
Sunflower meal is highly palatable and has a longer shelf-life. Those obtained from de-husked seeds are the best due to reduced fibre content allowing extensive usage in high-performing birds.
Also note that when it is overheated during the extraction processes, an essential amino acid, lysine, is destroyed.
Linseed meal does not effectively supplement the protein of maize or other grain in poultry diets. However, it is rich in phosphorus and has fair level of calcium but it should not exceed 3 to 5 per cent of the poultry diet since it is likely to depress growth and cause diarrhoea.
Alfalfa meal is also used extensively because of the high carotenoids but the inclusion level should be limited to 10 per cent.
Animal protein: Animal protein meals provide a good source of essential amino acids (like lysine and methionine) and are also good sources of energy and minerals, particularly calcium and phosphorus.
However, there can be significant variation in availability (absorption and retention) of amino acids due to the day-to-day difference in inputs as well as processing conditions (temperature, moisture, pressure and time).
The variation within processing plants can often be greater than that between plants. It is important for users to establish strict criteria as to the quality of product and work with their suppliers to ensure quality is met.
Fishmeal is high quality protein feed ingredient rich in all the essential amino acids, Vitamin B12 and choline. It is also a good source of calcium, phosphorus and riboflavin. When stored in hot climate, it can deteriorate in quality and should, therefore, be protected by the addition of an antioxidant.
High inclusion rates, above 10 per cent, may affect poultry meat and eggs, especially if low quality fishmeal is used.
Meat and bone meal is usually made from carcasses of animals that die on the farm, but not from diseases that are likely to be transferred to poultry.
The whole animal, except the skin and hooves, is cut up, cooked, dried, and then ground to form a meal. The quality will depend on the relative proportions and bone in sample but generally the meal is a good source of essential amino acids and minerals.
It requires addition of an antioxidant to prevent deterioration. It should be noted that if the meat and bone meal is outsourced, ensure it is from a safe source to prevent transfer of diseases.
Feather meal is also used as a protein source, however, care must be taken to prevent the dangers of infecting birds with diseases, particularly those caused by salmonella bacteria but this may be controlled through proper processing of feathers in steam and grinding the product.
Miyumi works with the Smallholder Indigenous Chicken Improvement Programme (www.incip.org/[email protected]), Department of Animal Sciences, Egerton University.