Serving Society through Food Animal Agriculture
January 2001
FEED AND ANIMAL MANAGEMENT FOR POULTRY[*]
Commercial poultry operations involve four types of birds, broiler chickens (meat producing), layer (table egg ) chickens, turkeys and ducks that differ greatly in size and their nutrient requirements. Breeder flocks for each of the major species are also a major part of the industry, and those flocks also have different nutrient requirements. Distinctly different diets are required for each of these species and the different stages of each species life cycle. These result in great differences in the volumes and nutrient compositions of the manure produced by the different groups. This fact sheet briefly highlights some factors affecting nutrient excretion. It also points out some potential dietary adjustments that can be made to minimize excess nutrient excretion. Nutrient requirements for birds that have potential environmental impact are listed in Table 1 (NRC, 1994). Reference to the NRC (1994) is imperative for a thorough evaluation of the poultry diets used by a commercial operation
Table 1. Selected nutrient requirements of poultry1
|
Nutrient |
Layer-80a,b |
Layer-100a,b |
Layer-120a,b |
Broiler 0-3 wk |
Broiler 3-6 wk |
Broiler 6-8 wk |
|
Protein, % |
18.8 |
15.0 |
12.5 |
23.0 |
20.0 |
18.0 |
|
Calcium,% |
4.06 |
3.25 |
2.71 |
1.00 |
0.90 |
0.80 |
|
Phosphorusc, %c |
0.31 |
0.25 |
0.21 |
0.45 |
0.35 |
0.30 |
|
Potassium, % |
0.19 |
0.15 |
0.13 |
0.30 |
0.30 |
0.30 |
|
Copper, mg |
? |
? |
? |
8 |
8 |
8 |
|
Zinc, mg |
44 |
35 |
29 |
40 |
40 |
40 |
|
Sodium, % |
0.19 |
0.15 |
0.13 |
0.20 |
0.15 |
0.12 |
|
|
Turkey 0-3 wk |
Turkey 3-6 wk |
Turkey 6-9 wk |
Turkey 9-12 wk |
Turkey 12-15 wk |
Turkey 15-18 wk |
|
Protein, % |
28.0 |
26.0 |
22.0 |
19.0 |
16.5 |
14.0 |
|
Calcium, % |
1.2 |
1.0 |
0.85 |
0.75 |
0.65 |
0.55 |
|
Phosphorus, %c |
0.6 |
0.5 |
0.42 |
0.38 |
0.32 |
0.28 |
|
Potassium, % |
0.7 |
0.6 |
0.5 |
0.5 |
0.4 |
0.4 |
|
Copper, mg |
8 |
8 |
6 |
6 |
6 |
6 |
|
Zinc, mg |
70 |
65 |
50 |
40 |
40 |
40 |
|
Sodium, % |
0.17 |
0.15 |
0.12 |
0.12 |
0.12 |
0.12 |
|
|
Duck 0-2 wk |
Duck 2-7 wk |
Duck Breeding |
Turkey Tom |
Turkey Hen |
|
|
Protein, % |
22.0 |
16.0 |
15 |
12.0 |
14.0 |
|
|
Calcium, % |
0.65 |
0.60 |
2.75 |
0.50 |
2.25 |
|
|
Phosphorus, % c |
0.40 |
0.30 |
? |
0.25 |
0.35 |
|
|
Potassium, % |
? |
? |
? |
0.4 |
0.6 |
|
|
Copper, mg |
? |
? |
? |
6 |
8 |
|
|
Zinc, mg |
60 |
? |
? |
40 |
65 |
|
|
Sodium, % |
0.15 |
0.15 |
0.15 |
0.12 |
0.12 |
|
a
Grams feed
intake per hen daily
b
Based on
dietary Metabolizable Energy concentration of approximately 2,900 kcal/kg (1318
kcal/lb) and an assumed rate of egg production of 90 percent (90 eggs per 100
hens daily).
c
Phosphorus
is non-phytate P.
1Adapted from Tables 2-3, 2-6,
3-1, 5-1 Nutrient Requirements of Poultry, 9th Revised Edition,
1994. National Research Council, National Academy of Sciences, National Academy
Press, 2101 Constitution Ave, Washington, DC 20418 (J. L. Sell, Chair,
Subcommittee on Poultry Nutrition)
Dividing
the growth period into several periods with a smaller spread in body weight
allows producers to provide diets that more closely meet the bird's nutrient
requirements. Phase feeding of several
diets during the grow-out period can significantly reduce N excretion. However, most companies cannot, primarily
due to mill ingredient handling restrictions, utilize more than 3 to 4 diets
for broilers, and 5 to 6 diets for turkeys.
New rapid growing genetic lines have been shown to have up to 69%
reduced P excretion, and up to 55% reduced N excretion as compared to older
slower growing genetic lines. These
reductions have come about primarily through reduced time to market age, and,
therefore, reduced maintenance requirements.
Some feed manufacturers are currently formulating poultry feeds on an
available amino acid basis. Synthetic
amino acids are often used to balance protein intake to closely match the birds
requirements for lean tissue protein synthesis and maintenance. Although
nutritionists cannot prepare a perfect amino acid balance from natural feed
ingredients, the use of computers and having an array of different feed
ingredients allows feed manufacturers to produce feeds that have reduced amino
acid excesses. This results in less N
being excreted. This is especially
critical because of potential nutrient variability in ingredient contents. Refer to NRC (1994) and consult certified
nutritionists to accurately evaluate current or planned diet composition during
the development of a CNMP. Few
commercial operations formulate diets based strictly on NRC recommendations
rather diets are based on new research that is often proprietary. Much recent research has demonstrated that
nutrient levels can be amended to reduce nutrient excretion and has the
potential to decrease feed cost.
Improve Feed Efficiency. Controlling feed wastage also improves flock feed conversion and reduces nutrient losses. Feed wasted in the manure pit and/or in the litter can add considerably to the nutrients that are to be applied to cropland. Maintaining birds under comfortable thermo-neutral environmental conditions also reduces feed consumption, improves feed utilization and thereby reduces nutrient excretion. Controlling diseases and parasites, and using good management practices are further examples of how one can improve the bird's health and growth rate, thereby improving its feed conversion efficiency and reducing its nutrient excretion. Fine grinding, expansion and further processing feed, i.e., into crumbles or pellets, are also effective ways in improving feed utilization and decreasing dry matter (DM), and nutrient excretion. By reducing the particle size the surface area of the grain particles is increased allowing for greater interaction with digestive enzymes. Addition of enzymes, such as phytase, amylase, protease, b-glucanase, etc., releases nutrients that also will enhance nutrient retention and reduce excretion. Supplementary inorganic minerals in the diet must, of course, be reduced if the normally non-digestible components of the diet are released through the use of enzymes, if nutrient excretion is to be reduced.
Formulate Diets on an Available Nutrient Basis. A high proportion (56 to 81%) of the P in
cereal grains and oilseed meals occurs as phytate. Phosphorous in this form is not well utilized by poultry because
they lack sufficient intestinal phytase, the enzyme needed to remove the
phosphate groups from the phytate molecule. Therefore, supplemental P is added
to the diet to meet the bird's growth requirements. The non-digestible P and
any excessive P added to the diet is excreted in the feces. Because some feedstuffs are high in phytate,
and because there is some endogenous phytase in certain small grains (wheat,
rye, triticale, barley), there is wide variation in the bioavailability of P in
feed ingredients. For example, the P in
corn is only 12% available while the P in wheat is 50% available. The P in dehulled soybean meal is more
available than the P in cottonseed meal (23 vs. 1%), but neither source of P is
as highly available as the P in meat and bone meal (90%), fish meal (93%) or
dicalcium phosphate (90-95%). Likewise,
P availability in different forms of dicalcium phosphate can vary from 89 to
100% compared to monocalcium phosphate (89-100%) Similarly, the sources of Cu and Zn used in the diet can vary in
availability for animal use. To reduce excretion levels, formulate these
nutrients on an available basis.
Supplementing the diet with the enzyme, phytase, is an effective means
of increasing the breakdown of phytate P in the digestive tract and reducing
the P excretion in the feces. Using
phytase allows one to feed a lower P diet because of the unavailable phytate P
in the grain and soybean meal is made available by the phytase enzyme to help
meet the bird’s P needs. The inclusion
of phytase increases the availability of P in a corn-soy diet by three-fold,
from 15% up to 45%. Broiler chicken
experiments have shown that non-phytate phosphorus levels may be reduced by 13%
resulting in a 24% reduction in excreted phosphorus. Addition of a vitamin D3 derivative,
25-hydroxy-cholecalciferol and citric acid has been demonstrated to increase
the absorption of phosphorus by 10%.
Inclusion of Lactobacillus
acidophilus in broiler diets will allow 18% lower dietary phosphorus and
result in a 25% decrease in excreted phosphorus. Also, research has
demonstrated that feed additives used in combination have potential to reduce
phosphorus excretion by more than 50%.
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