Effects of inclusion of guava fruit processing by-product in broiler diets on performance

Edith B Ogega, Charles K Gachuiri, Joyce G Maina and George O Abong’¹

Department of Animal Production, University of Nairobi. P.O. Box 29053-00625, Nairobi, Kenya
ogegaedith3@gmail.com
¹ Department of Food Science, Nutrition and Technology, University of Nairobi P O Box 29053-00625, Nairobi, Kenya

Abstract

The utilization of fruits processing waste as feed for animals can alleviate feed shortages in most developing countries and simultaneously help mitigate challenges in the environment that are caused by the dumping and decomposing of the wastes. The aim of this study was to determine the effects of inclusion of guava fruit processing by-product in broiler chicken diets on performance. The guava fruit processing by-product was incorporated in the diets at different levels to make four treatments: control 0% (GBO), 2.5% (GB2.5), 5% GB (5.0), and 7.5% (GB7.5). One hundred and sixty (160) day-old cobb-500 broiler chicks were allocated randomly to the four diets replicated four times with ten birds in each replicate. The amount of feed intake and weight gain were recorded and feed conversion ratio calculated. The digestibility of the 4 finisher diets was determined using the total fecal collection method.

The average daily weight gain was similar for GBO (56.53g), GB2.5 (54.88g), and GB5 (61.02g) respectively but significantly (p<0.05) lower at GB7.5 (45.68g) inclusion level. The average daily feed intake for GB7.5 (51.20) was significantly lower than GB5.0 (62.47) while intake for GB0 (59.03) and GB2.5 (59.21) did not defer from the 2 diets. Feed conversion ratio (FCR) did not significantly differ between diets. The DM and nutrient digestibility was not affected by diet. It was concluded that the guava processing waste could be included up to 5% in broiler diets without any adverse effects on performance thus contributing to food security by reducing the food: feed competition.

Key words: alternative feed, feed conversion ratio, feed intake, weight gain

Introduction

The world population is rising rapidly with much of the increase happening in Africa (Gerland et al 2014). By 2050, 60–70% more animal protein will be required in the world (Bakshi et al 2016). Increased output of poultry meat is inevitable, and it is likely to exacerbate the problem of scarcity and high prices of regular poultry feeds (Onsongo et al 2018). The livestock sector is one of the fast-growing subsectors of agriculture in developing countries, which has resulted in increased demand for animal feeds. Lack of high-quality feeds and food insecurity are the major problems in the developing world, leading to food-feed competition (Bakshi et al 2016).

The feed costs constitute the largest proportion of poultry production costs (Wainaina et al 2012). In intensive production systems, feeds account for 60-80% of the cost of production (MoLD 2008) thus alternate feed ingredients need to be frequently evaluated (Leeson and Summers 2005). Novel feed sources, especially those that do not compete with human food, are key in the development of the livestock sector. The major problem affecting the development of poultry farming is the high cost of commercial feeds due to the increase in the price of conventional feed ingredients that contain soybean meal, maize, meat meal, and fishmeal (Ravinadan 2009). In sub-Saharan Africa, maize serves as the primary energy source in animal feeds (Ochieng et al 2021), yet it is also the staple food for most communities. The traditional protein sources in poultry feeds are fish meal and soybean meal, and over time they have become expensive and scarce, thus increasing the cost of poultry feed (Van Huis, 2013; FAO 2013; Ochieng et al 2021).

In Kenya, the use of ingredients from the food processing industry, mostly from cereals, is common (MoLD, 2019). This is because much of the agro-industrial processing is based on cereals, as in many other developing countries where the population consumes diets with carbohydrate-rich cereals and less high-value meat, fruits, and vegetables (Industries & Development 2009). Consumers in developing countries are shifting their demand towards fruit and vegetable crops and their value-added products (Wadhwa et al 2013; Gehlhar et al 2014). The increase in demand for value-added products from fruits and vegetables has resulted in more byproducts which have potential to be incorporated in poultry feeds (Wadhwa et al 2015).

The guava tree produces many fruits annually with high profits and very low input. Many farmers taking up commercial cultivation of the guavas due to the profit margins (Singh 2007; Kadam and Kumar 2012; Omayio et al 2020). Due to its many nutrients, it is known as a super fruit (Verma et al 2013) as it contains high levels of natural vitamin-C compared to other sources of the vitamin such as oranges and tomatoes (Singh 2007). The byproducts from guava fruit processing include seeds, peels and fibrous tissue from the skin that are a result of pulping. By-products from fruits are known to be high in bioactive compounds plus dietary fibers (O’Shea et al 2015). The use of guava processing wastes as animal feed has recently been ranked highly by FAO (Bakshi et al 2016).

Guava wastes have been used in animal feeds including layers, broilers, pigs, lambs and rabbits. The use of guava wastes/by-products in poultry feed has been documented (El-Deek et al 2009; El-Deek et al 2009b: Oliveira et al 2018). There is no documentation on the nutritional composition and use of different guava fruit processing byproducts as feed in Kenya.

In Kenya, guava fruits are mainly grown for the fresh market, with an increase in production recorded in the year 2014 compared to the year 2013 (HCD 2014). There exists an unexploited potential of most fruits in Kenya, guava being one of them (HCD 2016). However, the area under guava production has also increased (HCD 2017). the information on guava production, utilization, consumption, the area under production, and commercial purposes is minimal (HCD 2014; Omayio et al 2019; Omayio et al 2020). There is a need for the development of structure and policy with the aim of maximizing the use of the guava fruits and reducing losses during post-harvest (Omayio et al 2019).

This study investigated the effects of the inclusion of guava fruit processing by-product in diets of broiler chicken on weight gain, feed intake, digestibility and carcass yield and characteristics.

Materials and methods

Raw material acquisition

This study was carried out at the poultry unit in the Department of Animal Production, Faculty of Veterinary Medicine at the University of Nairobi. Whole pink fresh guava fruits were harvested in Kitui and Taita Taveta Counties placed in gunny bags and transported to the pilot plant located in the Department of Food Science, Nutrition and Technology, Faculty of Agriculture, University of Nairobi. On arrival, they were washed using tap water to get rid of any dust/soil and debris or leaves then sorted depending on ripeness. The ripe guavas were crushed using a commercial crusher and sieved using a 0.5 mm stainless steel screen to separate the pulp and the waste that mainly consisted of the fruit peels and seeds. The waste was then transferred to the poultry unit in the Department of Animal Production, where it was sun-dried, ground using a hammer mill (3mm sieve), and stored in gunny bags. Samples were collected from different gunny bags and taken for laboratory nutrient analysis.

Diet formulation

Four diets were formulated such that they were iso-nitrogenous and iso-caloric. The control diet had 0% inclusion of guava waste, and the other three diets with inclusion levels of 2.5%, 5%, and 7.5% to make diets GB0, GB2.5, GB5 and GB7.5 respectively. The target for the energy content for both the starter and finisher phase was 3000Kcal/kg while the crude protein content target in the diets was 21% in the starter diets and 18% in the finisher diets. Table 1 shows the ingredients and the nutrient composition of the formulated diets.

Feeding experiment

One hundred and sixty day-old Cobb 500 broilers acquired from Kenchic Ltd were used for the experiment. Temperatures were maintained at 32°C during the first week, and reduced by 2 °C every week by adjusting the height of the infrared bulb, to 26°C by the end of the third week. For the first 3 days, all the chicks were fed on a composite of the 4 formulated diets. On the third day, the birds were feather sexed and randomly allocated into 16 cages (1m width x1m length x 0.9m height and floor covered with wood shaving to a depth of 10 cm), with each cage holding ten birds. Each experimental diet was allocated four cages to make 4 replicates. A plastic feeder and a plastic drinker were provided in each cage. The chicks were housed in a clean, well-lit and well-ventilated poultry house. They were vaccinated against Infectious Bursal Disease (Gumboro) on the 7th day and New Castle Disease on the 14th day. Any mortality that occurred in the course of the experimental period was recorded.

The experimental birds were fed in two phases: the starter phase (1-21 days) followed by the finishing phase (22-42nd days). Feed and water were provided ad libitum throughout the experiment period.

Data collection

Weight gain

The feed intake and weight gain of the birds were assessed weekly. On every first day of the experimental week, the birds in each cage were weighed by placing them into a tared plastic bucket and weighed using a digital weighing scale. The difference in the bird’s current week weight and their previous week’s weight was treated as the bodyweight gain.

Feed intake

The feed intake was determined by the weight difference between the initial feed availed at the start of the experimental week and the amount of feed remaining at the conclusion of the experimental week. At the beginning of the experimental week, a known quantity of the experimental diets was weighed for each respective replicate into a plastic bucket, from which feed was transferred into the respective plastic feeders throughout the experimental week. After seven experimental days, the feed remaining in the plastic feeders were scooped and put back into the respective buckets and weighed. The ratio of the weekly feed intake and weekly weight gain was used to determine the feed conversion ratio.

Digestibility trial

On day 43 of the experiment, one bird from each replicate was transferred into a metabolic cage for a digestibility trial. The birds were allowed 3 days to acclimatize to the new environment, and each bird continued on its previous experimental diet. Individual feed intake was determined by the difference between the amount of feed provided at the start of the experimental period and the amount of feed remaining after 4 days of digestibility data collection. Total fecal material was collected every day for four days from aluminum trays lined with polythene placed at the base of the cage. The trays were removed, and any material contaminating the fecal material were handpicked. The fecal material from each bird was weighed daily, thoroughly mixed, and sundried. The fecal material from each cage, collected and dried in the four days, was composited and sampled for chemical analysis. The nutrient digestibility was calculated using the formula below:

nutrient digestibility %=(( NF-NE)*100)/NF

Where NF = nutrient in feed and NE = Nutrient in Excreta (Mujahid et al., 2003)

Laboratory analysis

The guava waste, fecal material, and the formulated experimental diets were sampled for laboratory analysis. The analysis for Dry Matter (DM), Crude Fiber (CF), Crude Protein (CP), crude ash and Ether Extracts (EE) was done in accordance to standard methods (AOAC, 2005). Gross energy determination was done at the Kenya Industrial Research and Development Institute (KIRDI), using an Adiabatic Bomb Calorimeter.

Data analysis

All data obtained on feed intake, body weight gain, FCR, and digestibility trial were subjected to a one-way Analysis of Variance (ANOVA) using Genstat Discovery 14th edition (Payne et al 2011). Significant treatment means were separated using Bonferroni Multiple Comparison Procedure and the level of significance set at P ≤ 0.05.

Results

The chemical composition of the sun-dried guava by-product composed of peels and seeds after extraction of the pulp) is shown in (Table 1) while the nutrient composition of formulated diets is shown in (Table 2). The sun-dried guava by-product had a mean of 88.5% DM, 46.5% CF, 5.41% CP, 6.32% EE, 3.1% ash, and 38.7% NFE.

The crude protein content of the starter diets ranged from 21.2 to 21.3%, while in the finisher diet the range was from 17.8 to 18.7%. The diet with the highest guava waste inclusion had the highest crude fiber content, 8.88% for the starter diet and 11.0% for the finisher diet.

The feed intake (ADFI), weight gain (ADG) and feed conversion ratio (FCR) are shown in Table 3. During the starter phase, the ADFI tended to be lower for GB7.5 though not different (p= 0.132) compared to GB0 and the other experimental diets GB2.5 and GB5. The ADG was (p<.001) different between the diets with the highest recorded in GB5, followed by GB0 (control) then GB2.5, and lowest in GB7.5. The final weight at the termination of the starter period was highest in GB5, followed by GB0 (control), GB2.5, and lowest in GB7.5. The FCR was not influenced (p=0.102) by the different inclusion levels of guava fruit processing waste but broilers fed on GB7.5 had the highest though not markedly different FCR.

During the finisher phase, there was a marked difference (p=0.003) in ADFI, with broilers fed on GB7.5 having the lowest compared to other diets. The ADG was (p=0.006) influenced by the inclusion of different levels of guava waste. The ADG was high in treatment GB5, intermediate in GB2.5 and GB0 (control), and low in GB7.5. The final weight during the finisher period was the similar among broilers fed with GB0, GB2.5, and GB5 but low in GB7.5.

During the entire feeding period, the ADFI was highest for GB5.0 (62.5g/d) followed by GB0 and GB2.5 (59.0 and 59.2g/d) and lowest for GB7.5 (51.2g/d) with GB5.0 being higher (p=0.019) compared to GB7.5. The ADG was similar for broilers fed on GB0, GB2.5, and GB5 (56.5, 54.9 and 61.02 respectively) but lower (p<.001) for broilers fed on GB7.5 (45.7). The FCR was not affected by the different inclusions for the entire growth period.

Figures 1, 2 and 3 show the trend in daily feed intake, daily weight gain and feed conversion ratio observed with increasing of guava by-product inclusion level.

The different inclusion levels of the guava waste in the broiler finisher diets did not influence the apparent digestibility of DM, CP GE and CF in the diets (P > 0.05) as shown in Table 4. The apparent digestibility of dry matter ranged from 61.8 to 71.0, the crude protein from 54.6 to 65.0, and crude fiber from 40.3 and 53.0 and the GE ranged from 73.4 and 82.7%.

Figure 1. A chart to show the trend in feed intake with the increase of guava by-product inclusion level in the broiler diets

Figure 2. Effect guava subproduct level (%) on daily weight gain	Figure 3. Effect guava subproduct level (%) on feed conversion

Discussion

The CF content of the guava by-product was less than 56.0% reported by Lira et al (2009) for red guava fruit waste that contain pulp, peels, and seeds, 64.06% by (Silva et al 2009) and 59.2% reported by Kamel et al (2016). It was more than 40% documented by El-Deek et al (2009b) whose waste contained pulp, peel, seeds and inedible fruits, and 39.5% reported by El-Deek et al (2009) containing pulp and peel. The crude protein content was lower than 10.1% (Pereira et al 2009, Martins et al 2021) and 7.5% (Kamel et al 2016). The ether extracts (EE) of the guava by-product were lower than 10.86% recorded by Lira et al (2009), and 7.92% documented by Braga et al (2016) but higher than 4.52% reported by El-Deek et al (2009b). The ash content was lower than 5.62% reported by El-Deek et al (2009b) and higher than 2.52% recorded by El-Deek et al (2009), and 1.27% by Kamel et al (2016). The nitrogen-free extracts NFE was higher than 33.14 % recorded by El-Deek et al (2009b), and 32.97% recorded by El-Deek et al (2009). The differences in in nutrient composition by the different studies can be attributed to variations in the guava plants in different locations, different processing techniques and the different contents of the guava waste. (Kamel et al 2016)

The slight differences in the CP content of the formulated diets were attributed to the mixing and sampling errors and the inconsistent CP content of the ingredients used in the diet formulation. The increase in crude fiber content with increase in the inclusion levels was as a result of the high fiber content in the guava by-product.

The low feed intake observed for broilers fed GB7.5 can be attributed to the high fiber content that makes the feed bulky compared to the other diets. According to a study by Lira et al (2009), broiler birds that were fed diets with different inclusion levels of (3, 6, 9, or 12%) of guava waste showed an effect on feed intake during the 1st week with the 3% inclusion being the highest and the 12% having the least feed intake. This was attributed to the fact that the birds were trying to adapt to the experimental diets during the post-hatch period. Fiber is bulky and quickly fills the stomach limiting feed intake by the birds. In addition, soluble fiber tends to accumulate a lot of water and forms a gel that slows down the stomach emptying time and overall food transit time through the GIT (Jha and Mishra, 2021). This extends the time an animal feels “full” notably reducing feed intake which could explain the reduced intake observed in this study. In contrast, El-Deek et al (2009) observed that broilers fed on feeds with higher levels of guava by-product inclusion (6% and 8%) whether raw or processed greatly increased the amount of feed consumed compared to the diets with lower levels. According to the study, this was due to the considerably larger content of crude fiber in the meals having greater levels of guava by-products, which meant the birds were required to eat more to compensate their energy needs because monogastrics lack micro-organisms that break down fiber to give energy. El-Deek et al (2009b) fed laying hens with diets of differently treated guava by-products at different inclusion levels (5, 10, and 15%) also observed that the diet with the highest inclusion (10 and 15%) of guava by-product had the highest feed intake, an indication that guava by-product improved the diet palatability. The levels used in the study by El-Deek et al (2009b) were higher than the ones used in this study.

Other studies where guava fruit byproducts were fed to birds showed no effect on feed intake; Guimarães (2007) observed that layers fed on feeds with differing amounts of guava waste inclusion (0, 2, 4. 6 and 8 %) from week 30 to 39 had no influence in feed intake. Oliveira et al (2018) fed broiler birds with diets containing guava by-product at inclusion levels of 0, 0.5, 1.0, and 1.5% and observed no effects on the feed intake.

The lowest performance for all attributes was observed for birds fed at 7.5% inclusion of the guava byproduct which was related to the high content of fiber in the diet. The high fiber content decreased feed intake resulting in low weight gain compared to the other diets. The fiber in guava fruit by-products consists mainly of lignin and pectin (El-Deek et al 2009b). Pectin is a soluble fiber that tends to form a viscous gel-matrix that reduces the accessibility of products of digestion to the absorptive sites by coating the absorptive lining of the gut (Forman & Schneeman 1980; El-Deek et al 2009). Further, the gel-matrix can inhibit enzyme activity (Arnal-Peyrot & Adrian 1974; El-Deek et al 2009; El-Deek et al 2009b). A similar trend was reported by El-Deek et al (2009) where there was an improvement in average weight gain for the broilers fed diets containing 4% and 6% guava processing byproducts over the control diet, while those fed diets at 8% inclusion had a reduced daily weight gain. The authors attributed this poor performance to the high amount of fiber in diets containing 8% inclusion. Fiber has no energy value for non-ruminant animals because they do not have the necessary enzymes for its digestion and acts as a diluents of the energy content of the diet. Contrary, El-Deek et al (2009b) reported that layers fed on diets containing 10 and 15% of guava by-products had a remarkable increase in weight gain (159.5g and 153.6g respectively) compared to the control (78.7g) with no guava by-product inclusion an indication that there was a higher nutrient availability in feeds with more guava by-product inclusion compared to the diets with no guava by-product inclusion. Oliveira et al (2018), fed broiler birds with diets containing 0, 0.5, 1.0, and 1.5% of guava byproducts, and observed that the weight gain was increased linearly with increase of guava by-product inclusion.

There was however a reduction of weight gain with increased guava by-product inclusion in the 1^st week that was attributed to the birds being young with an immature digestive system and digestive enzyme production compared to older birds. Guimarães (2007) reported that guava by-product inclusion levels of 0, 2, 4, 6, and 8% did not notably affect weight gain in layer birds. A study by Lira et al (2009) reported no influence on the weight gain of broilers fed diets containing 3, 6, 9, and 12% guava by-products from the 2^nd to the 6^th week.

During the entire experimental period, guava byproduct inclusion level had no effect on feed conversion ratio (FCR) (1.57 to 1.72). This was an indication that the feed consumed by the birds was similarly utilized for gain for the different diets. Similarly, Lira et al (2009) fed broiler chicken on different levels (3, 6, 9 or 12%) of guava waste and reported an FCR of between 1.67 and 1.72 that was not significantly influenced by the increase in inclusion levels of guava waste. The results were also in agreement with those by El-Deek et al (2009) where the FCR of broiler finisher diets with different inclusion levels of guava by-product (0, 2, 4, 6 and 8%) was not affected. The values of the FCR were however higher (3.01 for the control and 2.78 for the experimental diets) than those in this study (1.4-1.5) an indication that the current study diets were more efficiently utilized than those used by El-Deek et al (2009).

It has been reported that from the ingested feed, broiler birds lose around 30% of dry matter (DM), 50% nitrogen, and 25% of gross energy (FAO 2013), in agreement with this study. The dry matter digestibility was not significantly influenced but it tended to lower for diet GB7.5 (61.7%) compared to the control GB0 (65.2%) and the other experimental diets GB2.5 (71.0%) and GB5 (69.5%). This was reflected in the growth performance where the broilers fed on GB7.5 had the least weight gain. Table 5 above showed that the digestibility of crude fiber was low compared to the other nutrients. Crude fiber contains both the soluble and insoluble non-starch polysaccharides and lignin fractions (Choct 2015). Both fractions can be utilized by broilers, thus the need to understand the role of each as there have been varied results in assessing their role in poultry nutrition (Tejeda and Kim 2021)

Conclusion

Incorporation of up to 5% guava fruit processing by-product in broiler rations improved feed intake and weight gain. The incorporation of guava fruit processing by-product in broiler feed at different levels did not have an effect on diet digestibility. Guava by-products can therefore be utilized in broiler feed formulation in order to contribute towards feed security.

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