Feather meal and its nutritional impact

India is emerging as a hot spot in the food processing scenario. The huge production of agricultural produce along with the diverse animal resources has made the country one of top food producing countries in the world. Newer trends and processing technologies are being taking into account for this purpose. In this regard the meat and poultry processing industry is booming; especially poultry production and processing, as the growth rate of it is very high. To guarantee the safety of chicken meat for consumers, an organised processing industry is gradually emerging. Today the modern broiler processing plants have the potential to process 200,000 to 1,000,000 birds per day, therefore tonnage of waste material are also produced. All waste material go through a by-product operation to convert it into value added commodities. The by-products are generally converted into animal feed, which is produced by rendering (cooking) the waste materials in hygienic conditions. Currently, Feather Meal (FM) is an underutilised protein source. A major reason for the lack of use of this product is due to very little information existing regarding the nutrient content of the product and its convenience.

Rich in protein

The most important poultry by-product at a rendering plant is FM. Feathers are rich in protein content called keratin and constitute 7% weight of the live bird, therefore producing a considerable mass which can be converted to valuable meal. Feather meal is also an excellent source of escape protein. Raw feathers are relatively insoluble and have a very low digestibility of 5% due to the high keratin content and the strong disulphide bonding of the amino acids, but with the controlled technology available today, we are able to convert a relatively insoluble protein into a palatable and highly digestible protein source for mulching ruminants. To make FM digestible it must first be converted through a hydrolysis process. Hydrolysation is completed by cooking the feathers with steam. Hydrolysed feather contents 40% to 65% moisture. This moisture must be reduced to 8% for improving shelf life as an animal feed.

Why to use FM

Feather waste from the poultry processing industry can potentially be used as a protein source in animal feeding operations. Improvements in current processing methods that hydrolyse proteins in feathers to make them more digestible for non-ruminant animals have led to the availability of high-quality hydrolysed FM that could provide a viable economic livestock feed. The crude protein content of feather meal does not suffer from the demerits of anti-nutritional factors like other available counter parts. During the 50’s and 60’s there was considerable prejudice against FM as a result of its low and variable digestibility which at that time was a reflection of the processing conditions. However, a considerable amount of research was carried out by several workers which has demonstrated that FM is a useful protein supplement for inclusion in broiler diets too.

Energy value of FM

The feeding value of feather meal is affected not only by protein, but also by energy content of it. For poultry and animal nutritionists, the relationship between energy and nutrients is important, if the energy content of feather meal is underestimated, then its inclusion in diets will lead to wider calorie-protein ratios, and may contribute to excess fat accumulation in the body. It is reported that the energy content of feedstuffs, especially FM in terms of TMEn, strongly depends on their chemical composition. The metabolisable energy content of well processed feather meal is, to a large extent, dependent on fat content in raw materials.

Initial work to determine the energy value of FM was carried out using broilers birds. It was considered that the NRC values were too low. Pesti, upon investigation of the initial data, found that when FM was included in diets at 40% level in the ration, the energy value was low, as the animals were unable to digest and absorb the amount of protein offered. But when it was used at the levels of 20%, the energy value was much higher than NRC published values (2.36 kcal/g) and it was suggested that a value of 3.07 Kcal/g (12.8MJ/kg) was more appropriate.True Metabolisable Energy (TMEn) values vary from 3092 to 3996 Kcal/kg and mainly depend upon the fat content of FM which varies from 1.8 to 12%. Metabolisable energy can be estimated from the fat content of well processed FM from the equation, TMEn (kcal/kg dry matter) = 2862 + 77(% fat).

Amino acid availability in FM

The direct relationship exists between the quality of an animal protein source and its available amino acids. In recent feed formulation, considerable attention has been focused on the available amino acids content of feed ingredients. Although the animal protein sources have high values of available amino acids and the availability of amino acids can vary greatly with the quality. There are many methods for the determination of available amino acids. Indirect assays for determination of availability include physical and chemical analysis method. In case of direct method, considerable attention has been focused on the precision for determination of digestibility of amino acids. There is need to determine the relationship between the quality of feed ingredients and their available amino acids. A significant amount of certain sulphur amino acids like cysteine, methionine and a sulphur derived component such as cystine are important for the proper growth and development. These amino acids play an important role in the growth performance. Liu et al. examined three samples of FM to determine true amino acid availability (AAA) and found that true AAA ranged from 59.2 (lysine) to 82.8% (arginine).

FM can be an integral part of poultry diets

A possible means of maintaining supply of broiler meat all year round at cheaper prices is by reducing the cost of production. Feeding of feather meal can fulfil the requirements for growth promoting protein in an economically viable form. Hydrolysed feather meal may be added up to 6% of the ration for broilers, 7% for layers and 5% for turkeys in well balanced diets, without harmful effect as far as production or health are concerned. Inclusion of the processed, water boiled feather meal up to 3.0% in the diets did not significantly affect mean body weights, feed intake, and feed conversion ratio of broiler chickens. The carcass data from the slaughtered chickens showed that birds fed diets containing 0, 1.5, and 3% feather meal had higher (P<0.05) carcass yields compared to those fed the 4.5% feather meal diet.>

Conclusion

FM is an excellent source of high quality protein but with the less digestibility, whereas with the easy application of some modified processing steps the quality of FM can definitely be increased. At low steam pressure, long hydrolysis times are needed to increase FM density and to improve digestibility. The easy availability of raw materials for the production of FM and economically viable processing methods can make it the most promising protein rich feed for both ruminant and monogastric animals. The energy value, amino acid composition and its availability has made it the first preference by animal owners. Based upon the price of FM, nutritionists should consider more regular use of this commodity. The effective utilisation of FM can surely increase animal production in terms of milk and meat; therefore it surely will secure its position in animal diets in the near future as a convenient, economically viable, protein rich feed ingredient for all sorts of domesticated animals.

References available upon request.

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