All About Feed 2014; 22/7: 34.
Anton C. Beynen
Why pick on feather meal in petfoods?
“Limited use of hydrolysed feather meal may be economically attractive”
Pet owners generally equate feathers with indigestible, unpalatable offal and marketers qualify
feather meal as a label-unfriendly, petfood ingredient. Feather meal, hydrolysed, has been legally
defined and is the ingredient name that must be stated on the label if present in the food. When
using ingredient category names, the descriptor is meat and animal derivatives. Some suppliers
recommend their hydrolysed feather meal for use in petfoods. In certain pet shops, dog food labels
with feather meal in the ingredient list can be found (1). About three years ago, the canine diet
called Anallergenic was introduced in the market of therapeutic foods. The diet contains a feather-
derived ingredient, which has evoked online cries of indignation.
Anallergenic contains oligopeptides and free amino acids produced by hydrolysis of feather protein
through a non-disclosed process. Veterinarians may prescribe the diet for dogs with suspected food
allergy and, if necessary, convince owners that it provides good nutrition. Diet efficacy carries back
to an unpublished clinical trial in dogs with true food allergy.
Enzymatic hydrolysis of proteins into sufficiently tiny fragments eliminates immune recognition by
allergic dogs (2, 3). Such protein hydrolysates are expensive and principally used in veterinary,
elimination and hypoallergenic diets. Anallergenic’s manufacturer asserts that working up feather
protein allows a highly advanced level of hydrolysis.
Amino acids and digestibility
The value of feather meal as protein source is determined by protein content, amino acid profile and
digestibility. Feather protein consists of keratin which requires pretreatment for accessibility by
digestive enzymes. Common hydrolysed feather meal is produced by pressurized cooking of
feathers, followed by drying and grinding. In-vitro pepsin digestibility is 75% or higher, depending on
production conditions (4).
Hydrolysed feather meal contains 80-85% crude protein. Digestibility has been determined by the
difference method. In both dogs and cats, 83% of ingested feather protein was not recovered in the
feces (5, 6). However, the proportion digested in the small intestine is unknown.
Apparent, overall digestibility of the protein in feather meal is similar to that in poultry meal (5), but
the latter has a higher content of lysine. Anallergenic has a crude protein content of 18%, fully
originating from the feather-protein preparation.
Palatability and feces quality
Many owners observe their pets regarding food palatability and stool characteristics. The
observations are considered indicators of food quality. Dry food containing 14% hydrolysed feather
meal was well accepted by dogs (4). Dogs fed dry foods containing 14 or 20% feather meal produced
more feces with somewhat higher moisture content and greater percentage off-shape (4, 5). This
might be caused by inefficient ileal digestion of feather meal. With 9% feather meal, aberrant stools
were markedly reduced (4). Meat mixed with hydrolysed feather meal (30% in dry matter) was
consumed readily by cats, but it increased feces quantity and water content, and also defecation
Reappraisal of feather meal
Moderate inclusion levels of hydrolysed feather meal, possibly up to 5%, may be safe, feasible and
economically attractive. For substantiated food formulation, ileal digestibility of the amino acids in
feather meal should be known.
The protein in Anallergenic is claimed to be sustainable because it comes from feather meal as a
waste product. However, sustainability is questionable because of intensive processing and animal
Shrinking inventories and increasing prices of ingredients may justify the use of hydrolysed feather
meal in petfoods. Dog and cat owners should become informed about the notion of nutritional value
of ingredients. Anallergenic might prove to be a swing toward hydrolysed feather meal finding its
way into petfood.
1. Beynen AC. Petfood label: ingredient list. Creature Companion 2014; June: 58-59.
2. Jackson HA, Jackson MW, Coblentz L, Hammerberg B. Evaluation of the clinical and allergen
specific serum immunoglobulin E responses to oral challenge with cornstarch, corn, soy and a soy
hydrolysate diet in dogs with spontaneous food allergy. Vet Dermatol 2013; 14: 181-187.
3. Puigdemont A, Brazis P, Serra M, Fondati A. Immunologic responses against hydrolyzed soy
protein in dogs with experimentally induced soy hypersensitivity. Am J Vet Res 2006; 67: 484-488.
4. Rebafka F-P. Adding value to feathers. Glodmehl®: A new potential for the petfood industy.
5. Gröner T, Pfeffer E. Digestibility of organic matter and digestible energy in single ingredients of
extruded dog feeds and their effects on faecal dry matter concentration and consistency. J Anim
Physiol Anim Nutr 1997; 77: 214-220.
6. Kienzle E, Meyer H, Schneider R. Investigations on palatability, digestibility and tolerance of low
digestible food components in cats. J Nutr 1991; 121: S56-S57.
7. Beynen AC. Green petfoods. Creature Companion 2015; March: 54-55.