Revised March, 1984
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
PUBLIC HEALTH SERVICE
FOOD AND DRUG ADMINISTRATION
CENTER FOR VETERINARY MEDICINE
These guidelines are the Center for Veterinary Medicine's (CVM) interpretation of new animal drug regulations in Part 514 (21 CFR Part 514) as regards the efficacy data requirements for pigmentation claims for poultry drugs. These guidelines supersede the 1975 Preclearance Guidelines for Production Drugs as they relate to pigmentation uses.
I. Background on the Pigmentation Mechanism and Sources of Pigment
Yellow corn, corn gluten meal, aztec marigold meal, alfalfa leaf meal, bermuda grass meal, algae meal, and possibly other green leaf meals are used in formulating broiler rations to enhance the yellow color of the broiler chicken carcass and in laying hen rations to enhance the yellow color of the egg yolk. The yellow color of the carcass and yolk is a result of xanthophyll and associated carotenoids in the feed being absorbed through the intestine, metabolized, and deposited in the skin and fat of the bird, or in egg yolk.
Under normal storage conditions for some of these feed ingredients, the xanthophylls and carotenoids are not very stable. The stability of xanthophylls has been enhanced by the manufacture of a liquid product which is made by extracting the xanthophyll from natural sources. The stabilized liquid product is then added to the mixer when the complete feed is manufactured, resulting in improved stability of the xanthophyll level in the complete feed.
The concentration of xanthophyll and associated carotenoids in the complete broiler feed is closely correlated to the intensity of the skin color in broiler chickens. It is generally accepted by poultry nutritionists that a concentration of 16 grams of xanthophyll per ton of complete broiler feed is adequate to produce a broiler of medium to light pigmentation. An unhealthy or diseased bird may appear pale and may not deposit the pigments as efficiently as a healthy bird. Many industry service men use skin color to aid in evaluating the health condition of the flock.
II. Color Additives
Color additives as defined in Section 201(t) of the Federal Food, Drug, and Cosmetic Act and 21 CFR 70.3(f), e.g., dried algae meal, Section 73.275(21 CFR 73.275), or Aztec marigold meal and extract, Section 73.295 (21 CFR 73.295), must be approved under the color additive section of the regulations (21 CFR 71.1) before they can be legally marketed or used in the formulation of poultry diets. This includes extracts of pigments from feed ingredients and other sources of naturally occurring pigments, or synthetic pigments. This guideline does not apply to color additive approval.
III. Rationale and Policy Statement
New animal drugs that increase rate of weight gain (or increase the rate of egg production) and improve feed efficiency may also improve carcass (skin/fat) and egg yolk pigmentation by enhancing xanthophyll utilization. Improved pigmentation is an effect closely associated with the improved feed efficiency and increased rate of weight gain claims and is attributed to improved absorption and subsequent deposition of the xanthophylls and carotenoids in skin/fat and egg yolk. CVM recommends the following wording for the carcass pigmentation claim, "improved carcass pigmentation," and the following wording for the egg yolk pigmentation claim, "improved egg yolk pigmentation."
The pigmentation claim would normally be approved for the single drug before it is approved in a drug combination.
(1) Carcass Pigmentation Claim
The pigmentation data may be collected from the same feeding trials as the growth and feed efficiency data. The three production claims (1) increased rate of weight gain, (2) improved feed efficiency, and (3) improved pigmentation are closely associated effects which are measured independently.
(2) Egg Yolk Pigmentation Claim
Data requirements are similar to those for carcass pigmentation. The protocol should indicate the frequency of egg yolk pigmentation scoring (e.g., whether one day/week, one week/month, 10%/day, or some other sampling is proposed), because 100% of the eggs produced would normally not need to be scored.
Data should demonstrate, in accordance with the current CVM "Guidelines for Drug Combinations for Use in Animals," that the combination of two or more drugs (whether marketed as a combination drug premix or marketed as single drug premixes to be combined in complete medicated feeds) is effective for improved carcass (or egg yolk) pigmentation claims. Under those guidelines, the combination should be shown to be superior to one or more of the component drugs (A statistically significant difference (P=.05) should be demonstrated).
IV. Protocol Design and Data Requirements
Protocols should be submitted to Document Control Staff (HFV-16), Center for Veterinary Medicine, Room 6B-45, Food and Drug Administration, 5600 Fishers Lane, Rockville, Maryland 20857, for review before studies are begun.
The method of statistical analysis should be determined in advance, and described in the protocol.
The same protocol design should be used for all trials so that data can be tested for homogeneity and pooled (if tests so indicate) for statistical evaluation.
Number of birds per replicate, number of replicates per treatment, and number of times the experiment is repeated depend upon expected differences and the ability to measure these differences. These matters should be discussed with a statistician during protocol development and included in the protocol.
The data should be collected from broiler (for carcass claims) or laying hen (for yolk claims) feeding trials conducted in at least three geographical locations from one day of age to market weight (7-8 weeks of age for broilers), or in the case of laying hens, from sexual maturity to a period representative of the egg production cycle.
The broiler feeding trials should be conducted in floor pens, starting with day-old, apparently disease-free chicks. Floor space per chick should be the same for all pens (at a single site), should be reported, and should simulate actual use conditions. Litter conditions, equipment, and housing should simulate actual use conditions, e.g., report whether clean litter or built-up litter is used. Lighting conditions should be reported and should be equal among treatments.
The laying hen feeding trials may be conducted in either floor pens or cages. Experimental conditions should be described similarly as with broiler feeding trials.
Diet formulas should include the percent of each feed ingredient, level of added vitamins, minerals, xanthophyll, and drug. The basal diet should contain normal levels of xanthophyll from natural sources. The diets should be analyzed for xanthophyll and drug levels (for each mix or batch). The diets should meet National Research Council requirements for nutrient composition. The raw data should be submitted for all observations, weights, and evaluations. A complete description of testing procedures and flock management should be provided.
For Single Drugs:
Treatments should be (a) control--no medication; and (b) only one drug, at one or more levels. If approval for a dose range is requested, three or more non-zero levels should be tested to adequately measure the dose-response.
For Drug Combinations:
Treatments should be (a) control--anticoccidial in feed; and (b) control (anticoccidial) plus one or more additional drug(s) at one or more levels. If more than one level, three or more non-zero levels should be tested to adequately measure the dose-response.
For specific guidance in protocol design, refer to the current CVM "Guidelines for Drug Combinations for Use in Animals."
V. Collecting the Pigmentation Data
Birds to be evaluated for pigmentation should be selected at the beginning of the study and identified by numbered wing bands. Double banding is suggested, i.e., one band on each wing.
A minimum of 20% of the birds from each replication, with approximately equal numbers of each sex, should be evaluated for pigmentation. However, if the 20% figure is less than six (6) birds, an absolute minimum of three males and three females should be evaluated from each replication (or pen).
Carcass pigmentation data may be obtained by:
(1) Visually scoring the degree of pigmentation in a specific area of skin or shank by using a color chart or fan as the standard;
(2) Chemically extracting the pigment from a specified area of skin, and using a spectrophotometer to determine the level of xanthophyll; or
(3) Employing a reflectance colorimeter (color eye) to determine the color density in a specific area of skin.
If a color fan (or chart) method is used and more than one observer scores the birds, the scores should be reported by observers, replication and treatment. Each observer should score birds from all treatments.
A complete description of the method used, including a description of the lighting in the work area in which the scoring was made and how the samples were prepared for scoring, should be submitted.
Egg Yolk Data
Egg yolk pigmentation data may be obtained by (1) separating the yolk from albumen and individually scoring the yolk color with a color fan or chart, or (2) individually assaying colorimetrically (Association of Official Agricultural Chemists, 1970). A percentage of eggs from each treatment should be scored at scheduled intervals (daily, weekly, biweekly, or monthly) throughout the egg production cycle.
VI. Other Methods of Data Generation
Protocols should be submitted to CVM for approval before collecting pigmentation data using methods other than those described in this Guideline.
VII. Literature References
The following references provide good summaries of the available literature on broiler pigmentation.
- Poultry Science 56: 953-956, 1977
- Poultry Science 50: 1467-1475, 1971
- Poultry Science 48: 1127-1129, 1969
- A.O.A.C. Methods 17.002, 1970
- NRC, Nutrient Requirements for Poultry, 1977
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