Feather Meal: Its Nutritional Value And Use In Dairy And Beef Rations

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The following article is a special collaboration from AFMA (Animal Feed Manufacturers Association)www.afma.co.za
We thank their kind support.

 

Feathers – The Raw Material
The American Association of Feed Control Officials (AAFCO) defines Hydrolysed Poultry Feathers as the product resulting from the treatment under pressure of clean, undecomposed feathers from slaughtered poultry, free of additives and or accelerators. Not less than 75% of its crude protein content must be digestible by the pepsin digestibility method.

There are over 1 million tonnes of feathers produced each year in the U.S. and as the consumption of poultry meat increases so will the production of this valuable raw material. Feathers have a protein content of around 84 percent and does not suffer from the disadvantages of anti-nutritional factors, such as tannins, glucosinolates, lectins and trypsin inhibiting factors. However raw feathers are relatively insoluble and have a very low digestibility of five percent due to the high keratin content and the strong disulphide bonding of the amino acids. Fortunately with the controlled technology available to us today, we are able to convert a relatively insoluble protein into a palatable and highly digestible protein source as seen in Table 1.

Table 1. Crude Protein content and Digestibility of various proteins.

Protein	C.P. %	Ruminant Digestibility %	Dig C.P. %
Feather meal	80.4	75	60.3
Fishmeal	65.0	92	59.8
Meat & Bone	50.2	86	43.2
Soybean Meal	45.3	90	40.8
Rapeseed Meal	35.9	84	30.1
Sunflower Meal	30.1	85	25.6

Production of Feather Meal

Feather meal (FM) is produced from fresh feathers that are steam hydrolysed under high pressure and temperature (140Ý C) for a period of time sufficient to hydrolyse the chemical bonds of the feathers. Hydrolysing can be carried out in batch cookers or continuos hydrolysers and is then followed by drying. Different processing conditions such as time, temperature, pressure and moisture can have an effect on the digestibility of the protein. Basically there is a rapid increase in the time required for processing when the pressure drops below 207 kPa and a rapid fall in time as the pressure rises above 207 kPa. More recently at least one company has proposed the use of enzymes as a ‘preconditioning agent’ prior to processing in a pressure vessel. The aim of this process is to increase amino acid availability and digestibility.

Feather meal produced under standard conditions from fresh feathers will have the following approximate analysis, Table 2:

Table 2. Typical Analysis of Feather Meal – Ewing 1997

Dry Matter	90%
Crude Protein	82%
Digestibility	75% min.
Fat	6%
Ash	4%
Crude Fibre	0.6%
Available Lysine	1.8%
Methionine + Cysteine	4.9%
TMEn	3.07 Kcal/g (12.8 MJ/kg)