Evaluating the growth performance and carcass quality of broiler chickens (Gallus gallus domesticus L.) through dietary supplementation with varying levels of dried coconut (Cocos nucifera L.) dregs as a substitute for copra meal

Jhuniel C Manuel, Ricnielyn A Damandaman, Chrisialyn C Carbilledo, Mark Anthony T Maña and Richelle A Niepes

College of Environment and Life Sciences, Mindanao State University at Naawan, Naawan, Misamis Oriental, Philippines 9023
richelle.niepes@msunaawan.edu.ph

Abstract

The escalating costs of traditional feed ingredients in animal farming necessitate exploration into alternative, cost-effective feed sources. Dried coconut dregs (DCD), a by-product of coconut milk extraction locally known as "sapal," represent a promising feed ingredient. Despite being considered waste, DCD presents significant potential for enhancing the economic viability of animal farming. This study aims to evaluate the growth performance, carcass characteristics and organoleptic qualities of broiler chickens fed diets incorporating DCD, thereby addressing existing research gaps. Thirty-six broiler chickens were subjected to four dietary treatments, each with varying proportions of DCD and copra meal. Growth parameters, carcass traits and organoleptic attributes were assessed using statistical analyses. Feeding broilers with diets containing DCD demonstrated notable effects on growth performance. Specifically, including DCD positively influenced feed intake and average daily gain, with the 30% DCD group exhibiting the highest performance. Moreover, carcass weight was significantly higher (p<0.05) in the 30% DCD group, indicating potential benefits for meat yield. Organoleptic evaluations revealed superior texture, aroma, tenderness and overall acceptability in broilers fed the 30% DCD diet. Integrating DCD into broiler diets could serve as a sustainable and economically advantageous strategy for poultry farming, while also addressing waste management concerns in the coconut processing industry.

Keywords: alternative feed ingredients, coconut processing industry, sapal, waste utilization

Introduction

Animal farming faces a constant challenge: the rising cost of feed. With traditional feed ingredients becoming more expensive and transportation costs adding to the burden, farmers are on the lookout for affordable alternatives. One potential solution lies in utilizing by-products from food processing. Dried coconut dregs (DCD), locally referred to as "sapal" in Cebuano, are essentially coconut meat from which the milk has been extracted (Figure 1). In the Philippine culinary practice, coconut milk is commonly used to prepare "bibingka," a popular rice cake delicacy (Figure 2). This traditional treat is often sold by vendors at bus stops and roadside stalls, particularly in locales like Lugait and Manticao in Misamis Oriental, serving as a significant source of income for many families to supplement their daily needs. However, this industry's residual "sapal" is considered waste and currently serves no further purpose (Sison et al 2019). There is a need to explore various value-adding opportunities for such by-products, such as utilizing them as feed for poultry and livestock.

The utilization of by-products from food processing as animal feed has been steadily increasing due to the escalating costs of conventional feeds. One such by-product is Copra meal (CM), a residue from oil extraction from dried coconut kernels. Copra meal has been utilized as a substitute for conventional feed ingredients in poultry rations, boasting an average protein content ranging from 19% to 22.4% . However, its use as a dietary protein source for poultry is limited by its high fiber and moderate essential amino acid contents (Kim et al 2001; Sundu et al 2009). Moreover, obtaining copra meal, even as a by-product, poses challenges for backyard farmers in the Northern Mindanao area due to its bulk sale at a commercial level with limited availability. Therefore, dried coconut dregs present a potential feed ingredient.

Dried coconut dregs (DCD) possess valuable nutritional components, rendering them a promising resource, particularly for animal feed applications (Syahri and Syahrir 2016). These components include a fiber content, which can enhance animal digestive health by promoting gut motility and reducing the risk of digestive disorders (Singh and Kim 2021). Moreover, DCD contains carbohydrates and fats, providing a viable energy source crucial for animal growth and production (Syahri and Syahrir 2016). Despite the comparatively lower protein content in DCD than other feed ingredients, it still significantly contributes to animals' overall protein intake. Furthermore, DCD may contain essential minerals and vitamins, such as potassium, magnesium and specific B vitamins, further supporting animal health and growth. Additionally, the fibrous nature of DCD can improve pellet quality in feed formulations, enhancing the manufacturing process of animal feed.

Utilizing locally available feedstuffs, mainly by-products from feed processing, offers a cost-effective and sustainable approach to mitigate the escalating feed costs in animal production. Studies have shown that fermented coconut dregs can improve body weight gain in broiler chickens (Hafsah et al 2020) and enhance digestibility (Sundu et al 2019). Additionally, supplementation with selenium in coconut dregs fermented with Saccharomyces cerevisiae has improved feed quality and broiler performance (Hatta et al 20 21).

While previous studies have explored fermentation and probiotic treatments of coconut dregs, yielding positive outcomes, these approaches entail significant resource, time and cost investments, particularly burdensome for backyard farmers in a developing country like the Philippines. However, research focusing on using dried coconut dregs, an untapped waste product in the food industry, without additional processing, remains largely unexplored. Hence, this study aims to assess the growth performance of broilers, carcass characteristics and organoleptic qualities, thereby addressing the gap in current research.

Materials and method

The study adhered to the animal welfare guidelines outlined in RA 8485 (Animal Welfare Act). It was conducted in Maria Cristina, Iligan City, Lanao Del Norte. The experimental site was slightly elevated and situated 500 meters away from the national road. The study spanned 35 days, comprising a brooding period of 14 days followed by a 21-day feeding trial.

Thirty-six broiler chickens were allocated across four treatments, each with three replicates and three birds per replicate, following a Completely Randomized Design (CRD). The treatments included: 30% CM (control diet); 15% DCD:15% CM (15% dried coconut dregs, 15% copra meal); 20% DCD:10% CM (20% dried coconut dregs, 10% copra meal); and 30% DCD (30% dried coconut dregs).

Coconut dregs were gathered from vendors selling bibingka along the roadsides or at bus stops in Lugait and Manticao, Misamis Oriental. They were inspected to remove any impurities or materials not relevant to the study. Subsequently, the coconut dregs were exposed to sunlight for 24 hours, with sun drying lasting between 3 to 5 days depending on the weather conditions. At night, the coconut dregs were stored in a dry room to prevent moisture absorption and protect them from liquid materials. After drying, the coconut dregs were sifted, scrubbed and sieved to separate larger lobes from finer particles. The finer particles were collected and utilized for formulation, while the larger clumps were manually broken by rubbing them between the palms. Samples of the dried coconut were then sent to the Mindanao State University's Naawan research laboratory for crude protein analysis and to the Department of Agriculture Region X in Cagayan de Oro to analyze dry matter, crude fat and ash content. The results of the proximate analyses are presented in Table 1.

The study involved feeding the broiler chickens three times daily: from 6:00 to 7:00 am, 10:00 to 11:00 am and 4:00 to 5:00 pm. During the feeding trial, the broiler chickens were given formulated feeds based on the requirements for the starter feed ration. The formulation of the experimental diets was presented in Table 2.

Data on growth performance such as feed intake, body weight gain and FCR were collected weekly and at the end of the experiment. To collect data on carcass characteristics and meat quality, a thorough procedure was implemented following the third week of the feeding trial, involving slaughtering thirty-six chickens. Each bird was handled carefully, adhering to standard procedures to ensure humane treatment and minimize stress.

Dressing percentage serves as a critical metric in understanding the efficiency of the slaughtering process, revealing the proportion of the animal's live weight retained as dressed carcass weight post-slaughter, following the removal of non-edible parts. This measure offers insights into the effectiveness of dressing procedures and can fluctuate based on various factors, including breed, age and management techniques. By assessing dressing percentage, researchers and producers can gauge the effectiveness of their practices and make informed decisions to optimize production processes and overall efficiency.

After slaughter, the weight of each chicken carcass was measured. This is the weight of the entire body without feathers, head, feet and internal organs.

Dressing percentage is calculated as the percentage of carcass weight relative to live weight before slaughter. It's calculated using the formula:

The carcass was then divided into different meat cuts (breast, thighs, wings, etc.) and the weight of each individual meat cut was measured. The weight of internal organs such as liver, heart, gizzard, etc., was calculated separately.

Meat cut-up yield is calculated as the percentage of meat obtained from the carcass relative to the carcass weight. It's calculated using the formula:

The formula for calculating organ yield on a live weight basis involves dividing the weight of the organ by the live weight of the animal and then multiplying the result by 100 to express it as a percentage.

In assessing the organoleptic characteristics of broiler breast meat when cooked, the study engaged fifteen panelists. The meat samples were prepared using the steam cooking method, following the procedure with slight modifications from the study by Takahashi et al in 2012. Prior to evaluation, the panelists were briefed on the sensory attributes they were to assess, including appearance, aroma, taste, tenderness and overall acceptability. The 10 g samples were coded to conceal the actual treatments, thus avoiding bias. Using a 5-point hedonic scale, with ratings ranging from "strongly dislike" to "strongly like," panelists provided their subjective assessments of each attribute for each sample.

The gathered data were subjected to one-way analysis of variance (ANOVA) and analyzed using SPSS software. Differences among treatments were determined by performing Tukey's post-hoc test. For the organoleptic characteristics of broiler breast meat, the Kruskal-Wallis non-parametric test was applied to determine significant differences among treatments. A significance level of p<0.05 was considered to indicate statistical significance.

Growth performance

The weekly growth performance of broiler chickens fed with varying levels of coconut dregs as a substitute for copra meal is presented in Table 3.The significant differences in feed intake among the groups across all three periods highlight the dietary preferences and efficiency of feed utilization by the broiler chickens. The decrease in feed intake among chickens fed with 30% dried coconut dregs (30%DCD) suggests a potential alteration in palatability or satiety levels associated with this dietary composition. Dried coconut dregs has a high fat content (see Table 1), which contributes to their elevated energy density. This characteristic makes them highly satiating for the animals, as the higher energy content in the diet can lead to increased feelings of fullness and reduced appetite (Benelam 2009). Chickens consuming the diet with a higher proportion of dried coconut dregs may feel more satisfied with their feed intake, resulting in decreased overall consumption compared to other dietary groups.

The absence of significant differences in the initial periods for average daily gain and weight gain suggests that the various dietary compositions have similar initial growth-promoting effects. However, differences were observed during the later stages, particularly in the last week (29-35 days). Chickens fed with a diet comprising 20% dried coconut dregs and 10% copra meal (20%DCD: 10%CM) exhibit significantly higher average daily gain and body weight gain than other groups. While no significant differences are observed in the first two periods for feed intake, indicating comparable feed efficiency among the dietary groups, variations become apparent in the later stages. The lower feed conversion ratio observed in chickens fed with 20% dried coconut dregs and 10% copra meal (20%DCD: 10%CM) during the last week suggests improved feed efficiency and nutrient utilization, potentially contributing to the observed higher growth rates and body weights in this group.

This discrepancy in growth performance between the initial and later periods can be due to the physiological development and metabolic changes that occur as broiler chickens mature. According to Ravindran and Abdollahi (2021), broiler chickens undergo rapid growth during the early stages of their life, driven primarily by genetic factors and environmental conditions. During this period, differences in dietary composition may have less pronounced effects on growth performance due to the chickens' high metabolic rates and energy demands. However, as broiler chickens approach market weight, their growth rate begins to plateau and metabolic efficiency becomes increasingly essential for maximizing weight gain while minimizing feed input (Vieira, & Angel, 2012). Moreover, the differential response to dietary composition observed in the later stages could be influenced by changes in nutrient requirements and utilization patterns as broiler chickens transition from rapid growth to maintenance and finishing phases. The nutritional needs of broiler chickens evolve throughout the production cycle, with specific requirements for protein, energy, vitamins and minerals varying at different stages of growth (Beski et al 2005). Therefore, dietary adjustments that optimize nutrient availability and utilization become more critical as broiler chickens progress towards market weight.

The table 4 presents the results of the overall growth performance of broiler chickens subjected to varying levels of coconut dregs as a substitute for copra meal in their diet., Chickens fed with 30% dried coconut dregs (30%DCD) displayed lower total feed intake compared to other groups, indicating a potential reduction in overall feed consumption associated with higher levels of coconut dregs in the diet. However, despite the lower feed intake, these chickens exhibited the highest average daily gain and total weight gain, highlighting the superior growth performance facilitated by diets rich in dried coconut dregs. Moreover, the chickens fed with 30%DCD demonstrated the lowest feed conversion ratio, signifying enhanced feed efficiency and nutrient utilization compared to other dietary compositions.

Figure 1. Average Daily Gain (ADG) of broiler chickens (g/b/day) fed with varying levels of dried coconut dregs (DCD) as a substitute for copra meal	Figure 2. Feed Conversion Ratio (FCR) of broiler chickens fed with varying levels of dried coconut dregs (DCD) as a substitute for copra meal

The results from the study indicate that despite copra meal's higher crude protein (CP) content, broiler chickens fed with dried coconut dregs exhibited superior growth performance. The nutrient composition of feed ingredients, particularly their energy density and digestibility, plays a crucial role in supporting growth and development in broiler chickens (Babatunde et al 2021). While copra meal may have a higher CP content, dried coconut dregs may essential nutrients, including fats, fiber, vitamins and minerals, which are vital for supporting various physiological functions in poultry . The higher energy density of dried coconut dregs, attributed to its elevated fat content, likely contributed to the superior growth rates observed in chickens fed with this dietary component (Mat et al 2022). Additionally, the palatability and digestibility of dried coconut dregs may have enhanced feed intake and nutrient absorption, ultimately promoting better growth performance in broiler chickens. The lower feed conversion ratio observed in chickens fed with dried coconut dregs further suggests improved feed efficiency and nutrient utilization compared to other dietary compositions.

Carcass characteristics

The table 5 presents carcass characteristics in broiler chickens fed diets with varying levels of dried coconut dregs as a substitute for copra meal. The results show that chickens fed with 30% dried coconut dregs (30%DCD) exhibited marginally higher carcass weights than other dietary groups. Despite this, no significant differences were observed in dressing percentage among the groups, indicating that overall meat yield was not substantially affected by including dried coconut dregs in the diet. However, among the dietary groups, significant variations were noted in the weights of specific carcass parts, such as thigh, drumsticks, neck, gizzard and heart. Chickens fed with 30%DCD displayed higher weights for these carcass parts, suggesting potential improvements in meat yield in these regions. Differences in the weights of other carcass parts, including breast, wings and feet, were not statistically significant among the groups. These findings indicate that while dried coconut dregs may influence the distribution of specific carcass parts, their overall impact on carcass composition and meat yield appears to be limited. During slaughtering, higher fat accumulations were observed in chickens fed with the 30% DCD diet, indicating that the higher dietary fat content from the dried coconut dregs may have contributed to increased fat deposition in the carcass.

Several factors, including genetics, nutrition, management practices and environmental conditions can influence high carcass weight in broiler chickens. Adequate nutrition supports optimal growth and development, ultimately contributing to higher carcass weights. Nutritional factors such as dietary energy, protein, amino acids, vitamins and minerals are crucial in promoting muscle development, bone mineralization and overall body composition in broiler chickens (Alagawany et al 2020). Dried coconut dregs, as a feed ingredient, can contribute to higher carcass weights through various mechanisms. Firstly, coconut by-products such as dried coconut dregs have a relatively high energy density due to their elevated fat content (Sundu et al 2020). Energy is a fundamental nutrient required for muscle growth and weight gain in broiler chickens. Therefore, diets containing higher levels of dried coconut dregs may provide the necessary energy resources to support increased carcass weights. Furthermore, dried coconut dregs may contain essential nutrients such as protein, vitamins and minerals, vital for promoting muscle development, bone health and overall growth in broiler chickens. The balanced nutrient profile of dried coconut dregs may improve nutrient utilization and efficiency, ultimately leading to enhanced growth performance and higher carcass weights in broiler chickens.

Organoleptic characteristics

Table 6 presents the organoleptic characteristics of broiler chicken breast meat influenced by varying levels of coconut dregs as a substitute for copra meal in feed. The parameters evaluated include color, texture, aroma, tenderness, taste, juiciness and overall acceptability, rated on a 5-point hedonic scale. In terms of color, no significant difference was observed among the different dietary treatments (p = 0.57). However, considerable variations are evident in texture, aroma, tenderness, juiciness and overall acceptability. Texture shows a significant improvement with increasing levels of dried coconut dregs (DCD) in the diet, with the highest rating observed in the 15% DCD: 15% CM group (p = 0.003). Similarly, aroma, tenderness, juiciness and overall acceptability exhibit significant enhancements with the inclusion of DCD, particularly at the 15% DCD: 15% CM and 30% DCD levels (p < 0.05). This suggests that substituting copra meal with DCD positively influences the sensory attributes of broiler chicken breast meat.

These findings align with previous research indicating the potential benefits of coconut by-products in poultry diets. For instance, a study by Khatibjoo et al 2017 found that high fat supplementation improved meat quality attributes in broiler chickens. The observed improvements in texture, aroma, tenderness, juiciness and overall acceptability could be due to nutritional composition of coconut dregs, which may enhance palatability and sensory characteristics of the meat.

Feed ingredients with high-fat content, such as coconut by-products, profoundly influence the organoleptic properties of broiler chicken meat. Dietary fat significantly impacts various aspects of meat quality, including texture, aroma, tenderness, juiciness and overall acceptability (Choi et al 2023). Fat contributes to the mouthfeel and texture of meat, resulting in perceived tenderness and juiciness due to increased moisture retention and lubrication during chewing (Lorenzo et al 2011). Moreover, fat plays a crucial role in carrying and enhancing flavors, thereby contributing to the development of desirable aroma compounds during cooking (Shahidi and Hossain 2022). As observed in broiler chickens fed diets containing coconut dregs, which are rich in fat, there is an improvement in texture, tenderness, juiciness and aroma of the meat, leading to higher overall acceptability among consumers. The nutritional composition of coconut dregs, particularly its high-fat content, likely underlies these positive effects on meat quality. Consequently, incorporating feed ingredients with high-fat content, such as coconut by-products, holds promise for enhancing broiler chicken meat's sensory attributes and consumer acceptability. The results suggest that incorporating dried coconut dregs as a substitute for copra meal in broiler chicken diets can positively influence the organoleptic characteristics of breast meat, potentially enhancing consumer acceptability and satisfaction.

Conclusion

The study reveals the beneficial effects of substituting copra meal with dried coconut dregs (DCD) in broiler chicken diets. Across various growth performance metrics, including feed intake, average daily gain and body weight gain, DCD diets consistently outperformed the control diet containing 30% copra meal (CM). The 30% DCD diet exhibited the most promising results, showcasing higher weight gains and improved feed conversion ratios. Additionally, carcass characteristics, particularly carcass weight, were significantly enhanced in the 30% DCD group, suggesting potential improvements in meat yield. Organoleptic evaluations further favored the DCD groups, particularly the 30% DCD group, which scored higher in texture, aroma, tenderness, juiciness and overall acceptability. Based on these findings, it is recommended to consider incorporating dried coconut dregs into broiler chicken diets, particularly at a 30% inclusion level, to optimize growth performance, carcass quality and consumer satisfaction. However, further evaluation of meat quality is advisable to discern whether the increased carcass weight stems from lean meat or fat accumulation from dried coconut dregs feeding.

Moreover, additional research exploring higher inclusion levels of coconut dregs could provide perspectiveinto the maximum feasible level and its effect. Investigating potential enhancements through supplementation with other affordable and accessible substances to improve protein content in dried coconut dregs could also be explored to further optimize broiler chicken diets.

Acknowledgement

The authors gratefully acknowledge the bibingka vendors in the municipalities of Lugait and Manticao for generously providing the coconut dregs used in this research. Additionally, we thank the Department of Agriculture Region X for analyzing the coconut dregs free of charge. Special thanks are extended to Chastine Erika G. Edubos and Mechie Ann C. Florida for their suggestions in improving this paper.

References

Alagawany M, Elnesr S S, Farag M R, Tiwari R, Yatoo Mohd I, Karthik K, Michalak I and Dhama K 2020 Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health – a comprehensive review. In Veterinary Quarterly (Vol. 41, Issue 1, pp. 1–29). Informa UK Limited. https://doi.org/10.1080/01652176.2020.1857887

Babatunde O O, Park C S and Adeola O 2021 Nutritional Potentials of Atypical Feed Ingredients for Broiler Chickens and Pigs. In Animals (Vol. 11, Issue 5, p. 1196). MDPI AG. https://doi.org/10.3390/ani11051196

Benelam B 2009 Satiation, satiety and their effects on eating behaviour. In Nutrition Bulletin (Vol. 34, Issue 2, pp. 126–173). Wiley. https://doi.org/10.1111/j.1467-3010.2009.01753.x

Beski S S M, Swick R A and Iji P A 2015 Specialized protein products in broiler chicken nutrition: A review. In Animal Nutrition (Vol. 1, Issue 2, pp. 47–53). Elsevier BV. https://doi.org/10.1016/j.aninu.2015.05.005

Choi J, Kong B, Bowker B C, Zhuang H and Kim W K 2023 Nutritional Strategies to Improve Meat Quality and Composition in the Challenging Conditions of Broiler Production: A Review. In Animals (Vol. 13, Issue 8, p. 1386). MDPI AG. https://doi.org/10.3390/ani13081386

Hafsah H, Damry H B, Hatta U and Sundu B 2020 Fermented Coconut Dregs Quality and Their Effects on the Performance of Broiler Chickens. In Tropical Animal Science Journal (Vol. 43, Issue 3, pp. 219–226). Media Peternakan. https://doi.org/10.5398/tasj.2020.43.3.219

Hatta U, Adjis A, Sarjuni S and Sundu B 2021 The use of Saccharomyces cerevisiae fermented coconut dregs with the addition of sodium selenite as a source of selenium in broiler diets. In IOP Conference Series: Earth and Environmental Science (Vol. 788, Issue 1, p. 012040). IOP Publishing. https://doi.org/10.1088/1755-1315/788/1/012040

Khatibjoo A, Mahmoodi M, Fattahnia F, Akbari-Gharaei M, Shokri A N and Soltani S 2017 Effects of dietary short- and medium-chain fatty acids on performance, carcass traits, jejunum morphology and serum parameters of broiler chickens. In Journal of Applied Animal Research (Vol. 46, Issue 1, pp. 492–498). Informa UK Limited. https://doi.org/10.1080/09712119.2017.1345741

Lorenzo J M, Temperán S, Bermúdez R, Purriños L and Franco D 2011 Effect of fat level on physicochemical and sensory properties of dry-cured duck sausages. In Poultry Science (Vol. 90, Issue 6, pp. 1334–1339). Elsevier BV. https://doi.org/10.3382/ps.2010-01140

Mat K, Abdul Kari Z, Rusli N D, Che Harun H, Wei L S, Rahman M M, Mohd Khalid H N, Mohd Ali Hanafiah M H, Mohamad Sukri S A, Raja Khalif R I A, Mohd Zin Z, Mohd Zainol M K, Panadi M, Mohd Nor M F and Goh K W 2022 Coconut Palm: Food, Feed and Nutraceutical Properties. In Animals (Vol. 12, Issue 16, p. 2107). MDPI AG. https://doi.org/10.3390/ani12162107

Ravindran V and Abdollahi M R 2021 Nutrition and Digestive Physiology of the Broiler Chick: State of the Art and Outlook. In Animals (Vol. 11, Issue 10, p. 2795). MDPI AG. https://doi.org/10.3390/ani11102795

Shahidi F and Hossain A 2022 Role of Lipids in Food Flavor Generation. Molecules (Basel, Switzerland), 27(15), 5014. https://doi.org/10.3390/molecules27155014

Singh A K and Kim W K 2021 Effects of Dietary Fiber on Nutrients Utilization and Gut Health of Poultry: A Review of Challenges and Opportunities. In Animals (Vol. 11, Issue 1, p. 181). MDPI AG. https://doi.org/10.3390/ani11010181

Sison M P M, Bracero R L, Laygan R M C, Pia G S M and Sinconiegue S G 2019 Establishing a Sustainable Community-Based Enterprise: The Case of Lugait Mamingkahay Association in Lugait, Misamis Oriental. In SSRN Electronic Journal. Elsevier BV. https://doi.org/10.2139/ssrn.3505839

Sundu B, Hatta U, Mozin S and Adjis A 2019 The effect of fermented coconut dregs with the addition of inorganic selenium on feed digestibility, growth performance and carcass traits of broiler chickens. Livestock Research for Rural Development. Volume 31, Article #176. Retrieved May 1, 2024, from http://www.lrrd.org/lrrd31/11/b_sun31176.html

Sundu B, Hatta U, Mozin S, Toana N, Hafsah Marhaeni and Sarjuni S 2020 Coconut meal as a feed ingredient and source of prebiotic for poultry. In IOP Conference Series: Earth and Environmental Science (Vol. 492, Issue 1, p. 012126). IOP Publishing. https://doi.org/10.1088/1755-1315/492/1/012126

Syahri Y F and Syahrir S 2016 Potency of Dregs Coconut Fermentation (Cocos nucifera) as an Alternative Feed for Fish and Poultry 'Pa-bio'. Agrotech Journal, 1, 45-49. https://doi.org/10.31327/ atj.v1i1.198

Takahashi H, Rikimaru K, Kiyohara R and Yamaguchi S 2012 Effect of Arachidonic Acid-enriched Oil Diet Supplementation on the Taste of Broiler Meat. In Asian-Australasian Journal of Animal Sciences (Vol. 25, Issue 6, pp. 845–851). Asian Australasian Association of Animal Production Societies. https://doi.org/10.5713/ajas.2011.11517

Vieira S L and Angel C R 2012 Optimizing broiler performance using different amino acid density diets: What are the limits? In Journal of Applied Poultry Research (Vol. 21, Issue 1, pp. 149–155). Elsevier BV. https://doi.org/10.3382/japr.2011-00476