Banana and Plantain Wastes 4: Use of banana and plantain peels as animal feed

Published Date: 31st August 2020

Introduction

Peels are the major wastes generated from banana and plantain fruits. Huge quantities of the peels are produced in many tropical countries, where plantain or the cooking type of banana are major staple foods. Banana peels are also produced as wastes in many urban and peri-urban markets in banana producing and consuming countries. The peel constitutes approximately 40 percent of the fruit, with an estimated 200 tons of waste being generated daily, and continues to increase as industrial processing of bananas become more common in many tropical countries. An estimated 18 – 20 percent of the banana peels are discarded as waste every year in such a manner that they constitute environmental problems. Traditionally, banana peels in the form of kitchen wastes are given to animals as feed. Many farmers offer banana peels to their animals because they are cheap, palatable, and readily available feed resources. In Nigeria, the production of chips from the unripe plantain also generates tons of plantain peels, which could be processed into feed raw material. Several research findings have therefore highlighted better techniques of optimizing the nutritional values of banana and plantain peels in animal production.

Banana peels are also used in wine, alcohol, and carbon black production, as a substrate for citric acid, biogas and mushroom production as well as material for pectin extraction. The peel ash because of its high content of potassium salts is used as alkaline for soap making and in the preparation of several traditional foods. In southeastern Nigeria, unripe banana and plantain peels are processed into chips and used to enhance the nutrient value of cassava chips-based dishes. Banana and plantain peels contain considerable amounts of plant bioactive compounds that protect the inner edible part from predator attacks. Based on this, banana peels are used in the production of highly insoluble dietary fiber, and antioxidant compounds both for health benefits, and functional foods development. They are relatively moderate in crude fibre, but rich in mineral matter, carbohydrate and certain vitamins. Other benefits of banana peels include its recent use in the preparation of nano-fertilizer blends to improve germination percentages of crops like tomato and fenugreek.

Nutrient composition of banana and plantain peels

The nutrient composition of banana and plantain peels is influenced by the stage of maturity and the cultivar. For example, dessert banana peel contains more fiber than plantain peel, while lignin content increases with ripening. Green plantain peel contains mostly starch which on ripening is converted into sugars, while green banana peel contains much less starch and more free sugars on ripening. Table 1 shows the proximate composition of ripe, and unripe plantain peels. The ripe peel has higher moisture, crude protein, crude fiber, and ash contents than the unripe peel. The unripe peel on the other hand has much higher ether extract, and carbohydrate values than the ripe peel, indicating that it could serve as energy source in animal diets. The sulfur-containing amino acids, methionine, and cysteine are moderately limiting in plantain protein, although it is well balanced with regard to the ratio of protein to calories, and considerably higher than those of maize, and other cereals. The protein content of banana peel is also low (6.36 – 10.8 percent), although the protein is rich in essential amino acids such as leucine, valine, phenylalanine, threonine. The crude fibre values in the peel range from 18.7 to 20.7 percent, while the ether extract ranges from 1.87 to 2.51 percent. The carbohydrate value also ranges from 53.2 to 62.1 percent, while the gross energy ranges from 3369 to 3494 Kcal/Kg, indicating that the unripe banana peel can also serve as an energy source in animal diets.

Potassium is the most abundant mineral in plantain peels, with an estimated value of 750 mg/kg in the unripe peel, which increases slightly during the ripening process. The ripe and unripe plantain peels have similarly high levels of zinc, magnesium, and manganese, while the unripe peel has higher calcium and iron values than the ripe peel. Banana peel also contains high levels of phosphorus, magnesium, sodium, iron, calcium, and potassium. Due to its low level of crude protein, banana peels are usually supplementation with protein-rich feedstuff in order to enhance their nutritive values.

Banana peels anti-nutrients and processing methods

The use of banana and plantain peels in animal feed formulation has been limited because of possible deleterious effects resulting from the presence of anti-nutrients, such as tannins, oxalate, and phytate amongst others. Tannins exist in the plantain peels in form of free or active tannins, which impart a strong bitter taste to the peel, and bound tannins or vegetable tannates, which are insoluble and have little or no effect on palatability. These anti-nutrients induce adverse effects such as depressed growth, reduced feed efficiency, and vital organ damage in the body, leading to mortality when fed fresh to poultry. Thus, there is a need for appropriate processing of the peels to detoxify these anti-nutrients.

Several methods such as the addition of ash, and cover for 3 - 5 days, sun drying for 4 - 5 days, oven drying for 2 hours at 100oC, and use of different alkali, and sodium hydroxide amongst others have been successfully used to reduce the anti-nutrient levels in banana, and plantain peels. During the sun drying process, the level of free tannin decreases because the tannins are slowly bound in an insoluble form. Although the level of free tannin is much higher in the peel than in the pulp, both are significantly reduced by sun-drying that reduces the moisture content to 10 percent. Researchers at the Federal Institute of Industrial Research, Oshodi (FIIRO), Lagos, Nigeria, have been able to produce dry banana peels for extended storage. The banana peels were sorted, washed with clean water, and spread openly on jute bags over the cemented floor, and under high sun intensity for 4 - 5 days until they were dried. They were thereafter, transferred to a cabinet tray drier, and dried at 125oC for 25 minutes, before cooling and further air-drying to obtain well dried crispy banana peels, which were packaged for onward milling. The moisture content of the dried peels on analysis was found to be less than 10 percent, while crude protein and fibre contents were 1.93 and 26.68 percent respectively.

Fermentation has also been used to improve the nutrient quality of banana peels by increasing the crude protein content, amino acids, and vitamin values. Fermentation also reduces the crude fiber, and anti-nutrients contents, which results in increased digestibility of the peels. During fermentation, metabolic processes with the help of enzymes produced from microbial aided oxidation, reduction, hydrolysis, and other chemical reactions, cause chemical changes in the organic substrate to produce a particular product. Fermentation can improve the nutrient quality of banana peels by increasing the crude protein, amino acids, and vitamins content while reducing the crude fiber contents, and increasing its overall digestibility. For example, the crude protein content of banana peels increased by about 54.02 percent from an initial 9.2 percent to 14.17 percent after fermentation with Rhizopus oligosporus.

In a study at Makerere University, Kampala, Uganda, researchers investigated the ensiling characteristics of banana peelings using naturally occurring bacteria. The fresh peels were packed in a polyethylene lined trench and covered to ensile for 28 days. It was concluded from the study results that since banana peelings lack the appropriate amounts of easily fermentable carbohydrates needed for good quality preservation, they should be ensiled together with materials rich in fermentable carbohydrates. Nigerian researchers at the Federal University of Technology, Akure, Nigeria, subjected ripe and unripe plantain peels to solid-state fermentation for seven days using pure fungal isolates, Aspergillus niger, A. flavus, and Penicillium sp. The A. niger, A. flavus, and Penicillium sp improved the crude protein content of the unripe and ripe peels by 34.0, 30.3, 2.3 percent and 9.5, 4.5, 4.0 percent respectively, indicating that the Penicillium sp may not be the ideal organism for seven days’ fermentation of the peels. However, on the 21st day of fermentation, the Penicillium sp increased the crude protein content by 39.8 percent. The ripe plantain peel fermented with A. flavus recorded a 142.6 percent increase in sugar content after seven days. There was also a corresponding reduction in the cellulose content of both peels with A. niger (300 percent reduction), indicating that the nutritional value of plantain peels could be increased by fermentation using A. niger, A. flavus, and Penicillium sp.

The nutritive value of banana and plantain peels for poultry

The use of plantain peels in poultry feeding has been generally limited by the deleterious effects of tannins present in the peel. Through the sun-drying process, the tannin content could be reduced to safe levels. Researchers at the University of Abuja, Nigeria, evaluated the performance of broiler chickens fed graded levels of ripe plantain peel meal as a replacement for maize. The peel meal was included at 25, 50, 75, and 100 percent levels in the diets, so that they contained averagely 23 and 20 percent crude protein in the starter, and finisher diets respectively. They reported that feed intake and weight gain decreased with increasing inclusion level of the peels, although the weight was gain slightly maintained at up to 75 percent inclusion level. They, therefore, concluded that ripe plantain peel could replace maize up to 75 percent in broiler diets for the best feed conversion ratio, and cost-efficiency.

The effects of fungal (Aspergillus niger) degraded plantain peel on the performance, nutrient digestibility, and other physiological characteristics of broiler finisher birds were also studied at the University of Ibadan, Nigeria. The peels were subjected to solid-state fermentation after inoculation with the fungal culture, and moistening with water at the rate of 300 ml per kg of the peel. After 7 days, the substrate was dried for 24 hours, and incorporated into the diets at 3, 5, and 7 percent inclusion levels. The highest weight gain and best feed conversion ratio were achieved with the 7 percent inclusion level, indicating that fungal biodegradation using A. niger has the potential of enhancing feed intake, nutrient digestibility, and the bodyweight gain of broiler finisher birds. Researchers at the Federal University of Technology Owerri, Nigeria, have also evaluated the effects of partial replacement of maize (25 and 50 percent levels), with 2:1:1 ratio of plantain peels, yam peels, and palm kernel cake in broiler starter diets. They reported that body weight gain and feed cost were significantly lower at the 50 percent level of maize replacement than others, while no significant difference in feed intake was observed among the various groups. They, therefore, concluded that plantain peels, yam peels, and palm kernel cake when combined in the ratio of 2:1:1 could optimally replace up to 25 percent of the maize in broiler starter diets.

The banana peel was also used to replace maize in a broiler study at the University of Maiduguri, Nigeria in order to determine the effect on growth performance, and other physiological parameters. The results showed that up to 15 percent replacement of maize with banana peel meal did not affect the performance of the broiler chickens, while there were reductions in feed cost N/kg, and feed cost per kg gain. Banana peel has also proved beneficial in alleviating the adverse effects of heat stress in poultry because of its high minerals, and essential vitamins (vitamin A 5.1%, 20% vitamin C, vitamin B,2,6%) content. This was evaluated in broilers by researchers at the University Padjadjaran, Bandung, Indonesia, using three rations containing banana peels at 10, 20, and 30 percent inclusion levels, and at an ambient temperature range of 28 – 35oC. At 20 percent inclusion level, no differences were recorded in final body weight, percentage carcass, and an abdominal fat percentage between the control and the experimental bird, indicating that 20 percent inclusion in the ration of broilers suffering from heat stress supports vital performance indices.

The nutritive value of banana and plantain peels for pigs

Feeding banana peels to pigs in smallholder farms has been an effective option for handling banana wastes since pigs can readily transform the inedible residues into high-quality meat products. Most smallholder farmers however feed the peel straight without any form of processing to enhance its nutrient value. In a study designed to evaluate the value of ripe plantain peel meal as a replacement for maize in the diets of growing pigs, researchers at the University of Science and Technology Kumasi, Ghana, reported that plantain peel can constitute as much as 20 percent of the diet while replacing 30 percent of maize. In another study, growing pigs were fed either 50, and 100, percent banana peel meal, or corn-soya or commercial ration as a control for three months. Feed intake of the pigs fed 50 percent banana peel was comparable to those fed corn-soya diet, and commercial diets, and was better than feed intake of pigs on 100 percent banana peel diet. However, the control feed was the costliest, while profits from pigs fed corn-soya diet was significantly higher than profit from pigs fed 50 percent banana peel diet, which in turn was better than profit from pigs fed 100 percent banana peel diet. Feeding growing pigs with diets containing up to 50 percent banana peel as a replacement for maize is therefore recommended.

Researchers at the University of Agriculture, Abeokuta, Nigeria have also evaluated the effects of replacing concentrates with plantain peels, and maize stalk on the performance of weaned pigs. Three diets in which the control contained 100 percent concentrate, and the other two contained the concentrate supplemented with plantain peels or maize stalk in the diet at the ratio of 40: 60 were fed to the animals for six weeks. The pigs fed the supplemented diets ate slightly more than the control pigs, which however had a better feed conversion ratio compared to the others. Again the supplemented diets were cheaper by as much as 35 to 41 percent than the control diet. These findings indicate that growing pigs could tolerate as much as 50 percent of plantain and banana peels in their diets without any deleterious effects.

The nutritive value of banana and plantain peels for ruminants

The potential of banana peels as ruminant feed material, based on their availability, and nutritional value is high when properly processed to eliminate its inherent anti-nutrients. To achieve this, banana peels have in different trials been treated with steam, ammonia, and silage fermentation to reduce its neutral detergent fiber, acid detergent fiber, cellulose, hemicelluloses, lignin, and silica contents. The best results have however been obtained by fermentation or ensiling process.

The effects of feeding varying levels of banana peels on the performance of lactating Friesian dairy cows was investigated by researchers at Makerere University, Uganda. The banana peels were offered at 0, 20, 40 and 60 percent levels of the total ration in addition to fresh elephant grass as basal diet, supplemented with maize bran, cottonseed cake, and dry Gliricidia sepium to achieve a balanced diet containing at least 11 to 12 percent crude protein. The feed supported moderate milk yield, while other performance indices of the animals were not affected as the level of the banana peels in the diets was increased. They however suggested that banana peels should not be offered solely because they are low in most nutrients and their inclusion level should not exceed 50 percent. The nutritive value of dried ripe plantain peels as a replacement of maize has also been evaluated in goats by a researcher at College of Education, Warri, Nigeria. The ripe plantain peels replaced maize at 0, 60, 80, and 100 percent levels in diets fed ad libitum for 84 days. Daily weight gains were higher at the 60 and 80 percent replacement levels, with values of 73 and 74 g/head/day, respectively, indicating that ripe plantain peel is acceptable and can replace maize in goat diets without adverse effects on growth performance. Both raw and ripened banana peels have been used to also feed sheep and were found to improve the degradability, volatile fatty acids production, and potential by-pass protein, at up to 40 percent inclusion level.

Conclusion

Traditionally, small-scale farmers offer banana, and plantain peelings to their animals because they are cheap, palatable, and readily available feed resources. Research has however shown that although they are rich in nutrients, they also contain anti-nutritional factors that affect their nutrient values for a different type of livestock. Several methods such as sun drying, oven drying, treatment with alkali or sodium hydroxide, and fermentation amongst others have been used to reduce the anti-nutrients to safe levels required for poultry, pig, and ruminant feeding.

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