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Contents
INTRODUCTION
TABLES OF NUTRIENT REQUIREMENTS
AND NUTRIENT CONTENTS OF FEEDSTUFFS
POULTRY FEEDS SHOULD BE HEAT TREATED
FEED STRUCTURE SHOULD BE COARSE
STARCH-RICH ENERGY FEEDSTUFFS
Maize
Wheat
Barley
Oat
Rye
Triticale
Rice
Cassava (tapioca, yucca, manioc)
Cereal
by-products
Distillers
solubles
PROTEIN FEED
SOURCES
Soy
Rapeseed
Cotton-, peanuts-,
sunflower-, linseed meals
Hampseed,
Peas
Lupins
Potato
proteins
Maize gluten
meal, lucerne meal and other pigment sources
Fishmeal
Meat meal
FAT
AMINO ACIDS
MINERAL
FEEDSTUFFS
VITAMINS
ENZYME
PREPARATIONS, FEED ANTIBIOTICS AND COCCIDIOSTATS
PROBIOTICS AND
PREBIOTICS
REFERENCES
Table 1.
Contents of protein, fat and carbohydrates in selected feedstuffs (% in DM)
and metabolizable energy for poultry
Table 2.
Effect of feed antibiotics and enzyme preparations on growth rate and feed
efficiency of broilers
Table 3.
Nutrient contents of feedstuffs
Table 4.
Feedstuffs ranked according to protein and methionine content. Protein total
contents of sulphur amino acids (met+cystine/cystein) and lysine in
feedstuffs, as well as is
Example of
feed declaration of a commercial layer diet
Example of
feed declaration of a commercial broiler diet
INTRODUCTION
This
presentation is teaching material meant to aid in exercises in feed optimization of poultry diets. You also need to have access
to data on nutrient requirements and nutrient contents of feedstuffs. This is
presented in different kinds of tables. For further information this
presentation is supplemented with internet links to further and deeper
information. These links may bring you to different kinds of websites, such
as authorities, universities and private companies, depending on what is
available.
TABLES OF NUTRIENT
RECOMMENDATIONS AND NUTRIENT CONTENTS OF FEEDSTUFFS
The table of
nutrient recommendations mostly referred to is the National Academy Press National Research Council
(NRC), “Nutrient Requirements of Poultry”. Such information is also supplied by breeder
companies adjusted to assumed needs of different genotypes. See for instance
recommendations by the Hyline company where
the production manual also includes data on different feedstuffs. Aviagen and Cobb-Vantress also present data for their broilers, Ross and Cobb,
respectively. The content of metabolizable energy in different feedstuffs
used by feed manufacturers in Sweden
can be found in Jordbruksverkets föreskrift om foder (SJVFS
2006:81). These values are based on the European table of feedstuffs (Janssen, 1986), where
adjustments may be done according to variations in nutrient
contents, depending on the background and processing of different
feedstuffs.
The nutrient content in common and some potential
feedstuffs for poultry in Sweden
is shown in Table 3 and in the feed optimization program Opti-kuckeliku. Approximate
figures on the use of different feedstuffs to different animal species may
also be found in statistics from the Swedish board of
Agriculture (www.sjv.se). These data are based on reporting
obligations by all certified feed manufacturers. In total about 500 million
kg of poultry feeds are produced, and about 75 % of the feedstuffs used
are domestic.
POULTRY DIETS MUST BE
HEAT TREATED
According to
the Swedish Animal Feed Act, foderföreskriften,
(SJVFS 2006:81) and the regulations for salmonella control poultry diets
must be heat treated (minimum 75°C). In practice all broiler diets are
preferably steam-pelleted, which will
give the same temperature effect. Also laying hen diets normally will be heated
by pelleting using a 3- or 5
mm dye, then crushed to crumbles. Heat-treatment may
be a problem at farm level, which is one reason why most poultry diets are
supplied by feed companies. Over-heating may decrease the digestibility of
the diet, implying increased excreta water content, which in turn may cause
wet litter and dirty eggs, impaired housing conditions and poorer bird
welfare.
FEED STRUCTURE SHALL BE
COARSE
Being grain eaters, birds have a digestive tract
designed to quickly ingest large amounts of
feeds, which are stored in the crop to be 'hydrated" and 'acidified' by
lactic acid secretions before passing through the proventriculus. In the
proventriculus, hydrochloric acid and pepsin and mucus secretions are
increased when feed particle size increases. The gizzard carries out feed
grinding, feed impregnation and predigestion of the feed by the secretions
from the proventriculus, as well as the regulation of feed in-flow and
out-flow. The gizzard is stimulated by a coarse feed structure, but the idea
that poultry need grits for their digestion is incorrect. More than 90 % of
all broilers in Sweden
are fed whole grains, mostly wheat, from one week of age, without any
addition of grit. A small feed particle size may reduce the gizzard's size and
function, and is suspected of
producing wet litter, with the same consequences as feed over-heating.
Grinding with a coarse sieve (not less than 5 mm) is to be preferred.
STARCH-RICH ENERGY
FEEDSTUFFS
Different kinds
of cereals are the basis of poultry diets, accounting for 50-60 and 60-70 %
of diets for layers and broilers, respectively. In Sweden, today, mainly domestic
grains are used, preferably wheat, triticale, barley, and oat, with a strong
preference for wheat. Also available on the world trade market are maize,
sorghum (durra, milo), cassava (tapioca, manioc) and rice, which is hardly
used in Sweden.
Grains are considered as "energy feedstuffs" because their protein
content is comparatively low, ranging from approximately 90 to 160 g/kg DM.
However, in total, cereals may contribute 50 and 40 % of the protein
requirement of layers and broilers, respectively. The energy content of
cereals is related to the content of fibre, approximately represented by specific
gravity (rymdvikt). The total
content of fibre may be calculated as dry matter (DM) minus the sum of ash,
protein, fat, starch and soluble sugar. Due to
differences in the hull fraction, the variation in energy content is higher
in barely and oat than in hull-less cereals, such as wheat. The figure
below shows the relationship between specific gravity and the content of
metabolizable energy in oat, barley, rye and wheat.
At feed
optimization feed companies mainly value cereals according to their price in
relation to their content of metabolizable energy (ME).
Considering today's prices of cereals this will favour the use of wheat and
triticale before barley and oat. To include e.g. oat, evaluation also has
to include other criteria than nutrient content, which accounts for the
difference between "simple computer users" and nutritionists.
Maize Read more about maize
Maize is the major energy
source in poultry diets in many parts of the world.
It may be used without any special nutritional restrictions. Due to its price
maize is little used in Sweden.
In southern Sweden
there is a minor producer using large
amounts of maize in diets for his broilers, raised according to a
special concept.
Read about wheat compared with maize
Wheat Read more about wheat
Wheat, supposing good hygienic quality, may comprise
the whole cereal part of the diet for layers as well as for broilers, and
in practice often does so. High wheat content is a risk, however, and may
cause problems as described below. In Sweden there are several
different autumn and spring varieties of wheat, with varying properties,
but our knowledge about the usefulness of different varieties for poultry is
limited. Autumn wheat is characterised as "white and soft"
and considered suited for rusks and soft pastry, while spring varieties are
"red and hard" and preferably used for baking. Here also so-called
durum wheats belong, with their high protein content but low protein quality.
These are mainly used for pasta. There are several crossings between these
original varieties on the market, and the feed industry does not distinguish
between them. The wheat crops in Sweden consist of about 90 %
autumn wheat, implying that feed mixtures mainly
contain autumn wheat.
As already mentioned, poultry prefer coarse feed particles. Finely ground
wheat may be sticky like chewing gum (gluten) when mixed with water, and
attaches to the beak of the birds, which may cause infections and decreased
feed intake.
Wheat in large amounts is reputed to induce feather pecking and cannibalism
in laying hens, which has been supported in several studies also showing
differences in sensitivity between bird genotypes. Therefore the content of
wheat in diets for layers, especially if kept in loose housing systems,
should be limited.
Wheat contains
β-glucan and pentosans (arabinoxylanes), which are charcterised as
so-called non-starch polysaccharides (NSP). NSPs are regarded differently in the nutrition of humans (benefits) and poultry (antinutritional substances). The
usefulness of wheat, especially for young broilers, benefits from the use of
enzyme preparations with xylanase activities.
Read about wheat compared with maize
Barley Read
more about barley
Baley, oat and
rye, as well as wheat, contain NSP. In barley β-glucan dominates, which is especially
antinutritional to young broilers. There are no endogenous enzymes for
metabolizing NSP. The detrimental effect is an increased digesta viscosity,
giving sticky droppings, which may adhere to the cloaca down during the
chicks’ first week of life, implying constipation. The birds’ water
intake increases and the litter bed will be wet and sticky impairing hygiene
and housing conditions. The risk for intestinal infection with toxin
producing Clostridium perfringens bacteria increases, which may
cause necrotic enteritis (NE). At the same time growth rate and feed efficiency
will be impaired. These negative effects caused by NSP may be reduced, as
mentioned concerning wheat, by adding an enzyme preparation to the diet with β-glucanase-, pentosanase- and cellulases activities.
As the birds get older the intestinal micro-flora will adapt and may produce
these enzymes, which is why enzyme supplementation is not as important for
older birds. NE is a "multifunctional disease" and there may also
be other factors than the diet that trigger the bacteria to produce toxins.
Care is recommended if using barley in broiler diets. Layers may be fed up to
about 30 %. Enzyme preparations are often used also for layers to
prevent problems of increased excreta water content and dirty eggs.
Oat Read more about oat
The hull fraction, being about 30 % of the total weight, limits the use of oat in mash feeds, where more than
15-20 % may cause hanging in feed silos and feed bins. Pelleting eliminates
this disadvantage. The low content of metabolizable energy in oat in relation
to price makes it unfavourable in comparison with other feed grains.
In countries
outside Scandinavia oat is scarcely used in poultry diets and the
unfavourable energy/cost ratio limits its use also in Sweden. However, from the poultry
producers point of view oat has several positive properties mostly overlooked
by the feed industry. Excellent production performance has been shown in
experiments both with broilers and laying hens with oat comprising the whole
cereal part of the diet. The fat content is higher in oat than in any other
grain. The comparable high amount of unsaturated fatty acids does not limit
its use, as it does in pig production. Oat contain more vitamins than any
other grain, among others vitamin A, E and C, which are
immune-stimulating antioxidants. Oat also has its own healthy antioxidants,
avenanthramides. Antioxidants function in helping to maintain the stability of
processed oat products, and oat can stabilise oils and fats against
rancidity. For poultry, the biological value of oat protein is higher than in
other grains. Incorporation of oats in poultry diets often shows positive
effects, which may be related to oat-fibre or perhaps other
"unidentified positive factors". Thus replacing wheat with oats has
been shown to decrease/prevent feather pecking in laying hens (read article in Swedish).
It appears that at least 10 % of oat in rations both for laying hens and
broilers may never be wrong.
Rye
Read more about Rye
Rye is rarely used for
poultry. The reason is primarily a high content of
antinutritional pentosans (NSP). Its usefulness for broilers is
dramatically improved by the addition of enzymes, but still only max. 5-10 %
can be recommended.
Triticale Read more about Triticale
Triticale is cultivated in large amounts, especially in Poland.
The harvest in Sweden
corresponds to about 15 % of the harvest of autumn wheat. The price is
the same or somewhat lower to wheat. The nutritional value and
usefulness for poultry varies with variety but is closer to wheat than
rye, and Triticale may replace most of the wheat content in diets for
poultry.
Rice Read more about Rice
Rice (paddy) contains on a weight basis about 20% hulls
and has to be dehulled before it can be used as human food. There are
also different grades of dehulled rice for animal purposes and supposing good
hygienic quality it is considered to be possible to include unlimited
amounts in diets for poultry if necessary. The outermost part of the hull
contains up to about 20 % silicate giving sharp edges and is not suited
as feed. The next fraction, consisting of pericarp-, aleuron-, germ- and part
of the endosperm layer has a high nutritional value but the hygienic
stability is low due to a high content (about 12 %) of rather unsaturated
fat. Extracted rice (- bran) is therefore to be preferred.
Cassava
(yucca, manioc) Read more about cassava
Cassava is a shrub that is extensively cultivated as an
annual crop in tropical and subtropical regions for its edible starchy
(tapioca about 70 %) tuberous root, a major source of carbohydrates. The
crude roots are poisonous since they contain cyanogenic glucosides, that
are toxic until these substances are removed by various methods.
Detoxificated roots can replace cereals in diets for poultry if their low
protein content is balanced in a suitable way. As with other feedstuffs
from tropical areas care has to be taken with respect to the hygienic
quality.
By-products
from cereals
Important milling by-products used for poultry include wheat-middlings and wheat-bran. The protein content and
quality are higher than in the grains. The middlings is the fraction of
the seed surrounding the endosperm. It has a less fibre and a higher energy content
than the bran fraction. Up to about 10 % middlings and 5 % brans may be
acceptable for chickens and somewhat more for laying hens. The development of
specialized enzymes may increase their usefulness in the future. Malt sprouts are obtained from malted barley by the removal of
the sprouts, and may include some of the malt hulls, other parts of the malt
and foreign material unavoidably present. It is an excellent feedstuff, which
can be included in poultry diets up to about 10 %.
Distillers dried grains
Read more about DDGS
Distiller's Dried Grains with
Solubles (DDGS) is a co-product of the distillery industries. Most (~98%)
of the DDGS comes from plants that produce ethanol for oxygenated fuels. The
remaining 1 to 2% of DDGS is produced by the alcohol beverage industry.
Distiller's dried grains with solubles are the dried residue remaining after
the starch fraction of maize or wheat is fermented with selected yeasts and
enzymes to produce ethanol and carbon dioxide. After complete fermentation,
the alcohol is removed by distillation and the remaining fermentation
residues are dried. Ethanol plants may use maize, milo, wheat, or barley in
the fermentation process, depending on geographical location and time of the
year. In Sweden
today mostly winter wheat is used, but in the future also triticale and
barley may be used. In 2008 550 thousand tons of cereals are predicted,
corresponding to the total poultry feed production, giving 150 thousand tons
of DDGS. Today DDGS are mostly used for pigs and ruminants. The increasing
supply and the high protein content (30-35 %) make the product interesting
also for poultry. In North America, where
maize is the main source, about 10 % is recommended. So far there have been
few studies carried out with wheat-DDGS for poultry, but it appears that it
is comparable with maize-DDGS. The nutrient content may vary with the grain
source and the process. The hygiene of the grain
source is of great importance since if grains arriving at the ethanol plant are
contaminated with mycotoxins, this will result in a further 3-fold concentration of
aflatoxins, fumonisin, zearalenone, T2 toxins, etc. The extraction and
fermentation of the grain starch, as well as the subsequent DDGS drying
process, will not eliminate these contaminants.
PROTEIN FEEDSTUFFS
The content of
carbohydrates is lower, but the proportion of antinutritional NSPs is often
higher in vegetable protein sources than in
cereals, which decreases the content of ME (Table 1). As is the case with
cereals research is going on to develop enzymes in order to increase the
utilization of NSPs (read an article).
Common protein feedstuffs for poultry are soybean meal, rapeseed meal and peas. Potato
protein and maize gluten meal are also used, especially in organic
production. Lupins, if
available, may also be used. There are several varieties, but sweet lupin,
which has a low content of toxic alkaloids is preferred.
Soybean, rapeseed, flax and sunflower, containing about 20, 45, 40 and 30 %
fat (oil), respectively, are examples of crops mainly cultivated for their
oil properties. The residues after oil extraction are valuable feed protein
sources. By convention "meal" is the by-product after extraction
with chemical solvents (for instance hexane). The "meals" (for
example soybean- and rapeseed meal) contain about 2 % fat at most. Oil can
also be mechanically extracted by different pressing techniques. The residue
is then named "expeller" or "cake", which contain more
fat/oil than the meal. The cakes are also good animal feed protein
sources, bringing more energy but less protein to the diet than the meals.
The high content of unsaturated fatty acids in vegetable oils increases the
risk of the cakes becoming rancid, which has to be considered. In diets for
organic poultry only cakes can be used, since processing with chemical
solvents is not allowed according to the IFOAM-standards.
Protein is built with
amino acids (aa) and the quality of the protein depends among other things on
the content of essential aa in relation to the animal's requirement. If there
is a 100 % agreement the protein aa composition is said to be "ideal". Essential nutrients are nutrients that
cannot be formed by the animal itself but have to be supplied by the diet.
The most important essential aa for poultry is methionine ("the first
limiting aa"). Thereafter lysine and then threonine may be
limiting. Figure 2 shows, with respect to methionine and lysine,
the "ideality" of the protein in some common feedstuffs for laying
hens.
Soybean
Read more about soybean
Soybean protein has a relatively
high biological value for poultry.
Crude soybean contains some antinutritional substances, trypsin inhibitors
being the most important ones, which have to be neutralized by heating
(toasting) before feeding. Soybean meal (SBM) is frequently used in diets for
poultry, and assuming good hygienic quality there is no upper limit. From the
hen's point of view, as with all legumes, soybean protein is rich in lysine
but poor in methionine (Fig. 2).
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FEEDSTUFFS AND DIETS FOR LAYING HENS 