Effects of encapsulated beetroot waste on growth performance, gut health and carcass characteristics of tegal ducks

Istna Mangisah¹, Lilik Krismiyanto¹ and Sugiharto Sugiharto²

¹Animal Nutrition Laboratory, Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Semarang, Indonesia
istnamangisah@gmail.com
²Physiology and Biochemistry Laboratory, Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Semarang, Indonesia

Abstract

The utilization of agricultural by-products as functional feed additives offers a sustainable approach to improving poultry production. This study evaluated the effects of encapsulated beetroot (Beta vulgaris) waste on growth performance, feed efficiency, intestinal microbiota, intestinal morphology and carcass characteristics of Tegal ducks. A total of 144 one-day-old Tegal ducks were randomly assigned to three dietary treatments with six replicates of eight birds per replicate. The treatments consisted of a basal diet without encapsulated beetroot waste (Brw0), a basal diet supplemented with 0.25% encapsulated beetroot waste (Brw0.25) and a basal diet supplemented with 0.50% encapsulated beetroot waste (Brw0.50). Growth performance, feed conversion ratio (FCR), intestinal microbial populations, intestinal histomorphology and carcass characteristics were evaluated during a 35-day feeding trial.

Dietary supplementation with encapsulated beetroot waste significantly increased (p<0.05) lactic acid bacteria (LAB) populations from 6.42 log CFU/g in Brw0 to 6.56 and 6.87 log CFU/g in Brw0.25 and Brw0.50, respectively, whereas coliform populations were not affected (p>0.05). Ducks receiving encapsulated beetroot waste exhibited greater villus height and villus-to-crypt ratio in the duodenum, jejunum and ileum than those fed the control diet (p<0.05). Total body weight gain increased from 777.08 g in Brw0 to 787.91 g and 792.25 g in Brw0.25 and Brw0.50, respectively (p<0.05). Total FCR improved numerically from 3.67 in Brw0 to 3.63 and 3.60 in Brw0.25 and Brw0.50, respectively. Carcass percentage was significantly higher (p<0.05) in supplemented ducks, reaching 65.00% in Brw0.25 compared with 63.00% in the control group.

It can be concluded that encapsulated beetroot waste improved gut microbial balance, enhanced intestinal morphology, increased growth performance and improved carcass yield in Tegal ducks. Supplementation at 0.25% was the most effective level for improving carcass percentage, whereas 0.50% provided the greatest benefits for intestinal health and growth performance.

Keywords: beetroot waste, encapsulation,  growth performance, gut microbiota, intestinal morphology, Tegal ducks

Introduction

Duck production plays an integral role in sustaining the animal protein supply and rural livelihoods in many developing countries, including Indonesia. However, increasing feed costs and restrictions on the use of antibiotic growth promoters (AGPs) have encouraged the search for sustainable feed additives capable of improving productivity while maintaining animal health. Feed efficiency remains one of the most important determinants of profitability in poultry production because feed accounts for approximately 60–70% of total production costs. Therefore, natural feed additives that can enhance nutrient utilization and gut health are receiving increasing attention in modern poultry nutrition (Khomayezi and Adewole 2022; Obianwuna et al 2024).

In recent years, agro-industrial by-products have emerged as promising feed resources due to their nutritional value and bioactive compound content. The utilization of agricultural waste as feed additives not only reduces environmental burdens but also contributes to sustainable livestock production systems. Among these by-products, beetroot (Beta vulgaris L.) waste has attracted considerable interest because it contains a wide range of biologically active compounds, including betalains, polyphenols, flavonoids, phenolic acids, vitamins and dietary fiber (Stoica et al 2025; Ahmed et al 2026). These compounds exhibit antioxidant, anti-inflammatory, antimicrobial and immunomodulatory properties that may improve intestinal health and performance (Ahmed et al 2026).

Beetroot-derived bioactive compounds have been reported to improve antioxidant status, modulate intestinal microbiota, enhance nutrient digestibility and support productive performance in poultry. In particular, betalains and phenolic compounds are able to counteracting reactive oxygen species, lowering oxidative stress and maintaining intestinal integrity. Improved gut health is closely associated with enhanced villus development, greater nutrient absorption capacity and better feed utilization efficiency. Furthermore, phytogenic feed additives rich in polyphenols have been shown to promote beneficial bacterial populations, particularly like lactic acid bacteria, while suppressing intestinal dysbiosis, thereby leading to improved growth performance and carcass quality in poultry (Das et al 2020; Khomayezi and Adewole 2022; Obianwuna et al 2024).

Despite their biological potential, the application of beetroot by-products in poultry feeding is often limited by the instability of bioactive compounds during feed processing and storage. Polyphenols and betalains are susceptible to degradation caused by heat, oxygen, moisture and digestive conditions, which may reduce their biological effectiveness. Encapsulation technology has been increasingly utilized to protect sensitive bioactive compounds, improve their stability and facilitate targeted release in the gastrointestinal tract. Encapsulated phytogenic additives have demonstrated beneficial effects on intestinal morphology, gut microbial balance, nutrient utilization and growth performance in poultry species (Obianwuna et al 2024). Furthermore, encapsulation has been reported to enhance the bioavailability and efficacy of plant-derived phenolic compounds by mitigating their breakdown during feed processing and digestion (Marcillo-Parra et al 2021).

Although the beneficial properties of beetroot and other phytogenic additives have been extensively documented, information regarding the use of encapsulated beetroot waste in duck nutrition remains scarce, particularly concerning its effects on gut microbiota, intestinal morphology, feed efficiency and carcass characteristics. Most previous studies have focused on broiler chickens or laying birds (Khomayezi and Adewole 2022; Obianwuna et al 2024; Ahmed et al 2026), whereas evidence in local duck production systems is still limited. Moreover, the utilization of beetroot processing waste as a value-added functional feed additive has not been fully explored, despite its potential contribution to sustainable poultry production and agricultural waste valorization.

Therefore, the present study was conducted to evaluate the effects of dietary supplementation with encapsulated beetroot (Beta vulgaris) waste on growth performance, feed conversion ratio, intestinal microbiota, intestinal morphology and carcass characteristics of Tegal ducks. It was hypothesized that encapsulated beetroot waste would improve gut health and nutrient utilization, resulting in enhanced growth performance and carcass yield.

Materials and methods

Birds and experimental diets

The experiment was conducted at the Experimental Farm, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Semarang, Indonesia. A total of 144 one-day-old Tegal ducks were randomly assigned to three dietary treatments with six replicates per treatment and eight birds per replicate. The feeding trial was conducted for 35 days. Feed and drinking water were provided ad libitum throughout the experiment.

The basal diet was formulated to meet the nutrient requirements of growing ducks and its composition is presented in Table 1. The dietary treatments consisted of:

• Brw0 = basal diet without encapsulated beetroot waste (control)
• Brw0.25 = basal diet supplemented with 0.25% encapsulated beetroot waste
• Brw0.50 = basal diet supplemented with 0.50% encapsulated beetroot waste

Preparation of encapsulated beetroot waste

Beetroot (Beta vulgaris L.) waste extract was encapsulated using maltodextrin as a coating material. Maltodextrin was dissolved in distilled water at a ratio of 1:10 (w/v), while beetroot extract was dissolved in distilled water at a ratio of 1:5 (w/v). The maltodextrin solution and beetroot extract solution were mixed at a ratio of 3:1 and homogenized using a magnetic stirrer. The resulting mixture was subjected to freeze-drying to obtain encapsulated beetroot waste powder. The encapsulated powder was stored at 4°C until use.

Growth performance measurements

Feed intake and body weight were recorded weekly. Body weight gain (BWG) was calculated as the difference between final and initial body weight. Feed conversion ratio (FCR) was calculated as feed intake divided by body weight gain during each observation period and for the entire experimental period.

Intestinal microbiology and histomorphology

At 35 days of age, one duck representing the average body weight from each replicate was selected and slaughtered for intestinal sampling.

Intestinal microbiology

Digesta samples were collected aseptically from the small intestine and homogenized in sterile physiological saline solution (0.85% NaCl). Serial ten-fold dilutions were prepared and plated using the spread plate method. Lactic acid bacteria (LAB) were enumerated on de Man, Rogosa and Sharpe (MRS) agar, while coliform bacteria were enumerated on MacConkey agar. The inoculated plates were incubated at 37°C for 24–48 h. Microbial populations were expressed as log colony-forming units (CFU) per gram of intestinal digesta according to standard microbiological procedures (Cappuccino and Welsh 2017; Mangisah et al 2020).

Intestinal histomorphology

Samples of the duodenum, jejunum and ileum (approximately 2 cm in length) were collected immediately after slaughter and fixed in 10% neutral buffered formalin. The samples were dehydrated through a graded ethanol series, cleared in xylene, embedded in paraffin, sectioned at 5 μm thickness and stained with hematoxylin-eosin (H&E).

Histological observations were performed using a light microscope equipped with an image analysis system. Villus height was measured from the tip to the villus–crypt junction and crypt depth was measured from the crypt base to the junction. Ten villi and crypts were measured per sample and the villus height-to-crypt depth ratio (V/C ratio) was subsequently calculated as an indicator of intestinal absorptive capacity and epithelial turnover (Awad et al 2009; Abdelli et al 2021).

Carcass characteristics

At the end of the experiment (35 days of age), ducks were weighed before slaughter to determine live body weight. After slaughtering, defeathering and evisceration, skin weight, carcass weight and skinless carcass weight were recorded. Carcass percentage was calculated as:

Carcass percentage (%) = (Carcass weight / Live body weight) × 100

Statistical analysis

The experiment used a completely randomized design (CRD) with three dietary treatments and six replicates per treatment. Data were evaluated by analysis of variance (ANOVA) using statistical software (SPSS) version 25. Differences among treatment means were considered significant at P<0.05 and were separated using Duncan's multiple range test.

Results and discussion

Dietary supplementation of encapsulated beetroot waste significantly influenced several indicators of gut health and productivity in Tegal ducks (Table 2 and 3). The population of lactic acid bacteria (LAB) increased significantly (p<0.05) with increasing supplementation levels, reaching the highest value in Brw0.50 (6.87 log CFU/g), while coliform counts remained unaffected (p>0.05). Supplementation with encapsulated beetroot waste improved the villus height and the villus height-to-crypt depth ratio throughout the small intestine (p<0.05). Duodenal and ileal crypt depth were also affected by treatment, whereas jejunal crypt depth remained unchanged (p>0.05). Feed conversion ratio demonstrated to improve with increasing supplementation level, although the differences were not statistically significant (p>0.05). Carcass percentage was significantly improved by treatment (p<0.05), with the highest value observed in ducks fed 0.25% encapsulated beetroot waste (Brw0.25), indicating enhanced nutrient utilization and carcass yield efficiency.

Dietary supplementation of encapsulated beetroot waste significantly increased intestinal lactic acid bacteria (LAB) populations, indicating its potential prebiotic effect. Beetroot waste contains polyphenols, flavonoids, betalains and fermentable carbohydrates that can selectively stimulate beneficial microorganisms in the gastrointestinal tract. Increased LAB populations contribute to gut health by producing organic acids, lowering intestinal pH and improving microbial balance, thereby creating a more favourable intestinal environment for nutrient utilization (Das et al 2020; Khomayezi and Adewole 2022).

The lack of significant differences in coliform populations among treatments suggests that encapsulated beetroot waste selectively promotes beneficial bacteria rather than exerting broad antimicrobial activity. Such selective modulation is desirable because it supports intestinal microbial homeostasis without disrupting the overall microbial ecosystem. Encapsulation likely enhanced the stability of beetroot bioactive compounds during digestion and facilitated their release in the intestinal tract, improving their interaction with resident microbiota (Qazi et al 2025; Obianwuna et al 2024).

The improvement in intestinal microbial balance was accompanied by significant changes in intestinal morphology. Ducks supplemented with encapsulated beetroot waste exhibited greater villus height and higher villus height-to-crypt depth ratios (V/C) in the duodenum, jejunum and ileum. An enhancement in villus height expands the absorptive surface area, while a higher V/C ratio indicates improved digestive and absorptive efficiency. Similar improvements in intestinal morphology have been reported in poultry receiving phytogenic feed additives rich in antioxidant compounds (Abdelli et al 2021; Obianwuna et al 2024).

The higher V/C ratios observed in supplemented ducks suggest a more favorable balance between nutrient absorption and epithelial tissue turnover. Both supplemented groups exhibited higher villus height-to-crypt depth ratios than the control group, while no significant differences were observed between Brw0.25 and Brw0.50. Improved intestinal architecture enhances nutrient digestibility and reduces the energy required for epithelial renewal, allowing greater nutrient allocation for productive functions (Obianwuna et al 2024; Das et al 2020).

The improved intestinal morphology and increased LAB populations likely contributed to the numerical improvement in feed conversion ratio observed in supplemented ducks. Although differences in FCR were relatively small, the trend toward lower FCR values suggests enhanced feed utilization efficiency. Beetroot-derived polyphenols and betalains possess antioxidant activity that may reduce oxidative stress in intestinal tissues, thereby supporting epithelial integrity and nutrient absorption (Stoica et al 2025; Khomayezi and Adewole 2022).

Dietary supplementation did not affect feed intake, indicating that encapsulated beetroot waste neither impaired palatability nor altered voluntary feed consumption. Therefore, the improvement in body weight gain was likely associated with better nutrient utilization rather than increased feed intake.

Feed intake was not affected by dietary supplementation of encapsulated beetroot waste (p>0.05), indicating that inclusion levels up to 0.50% did not negatively influence diet palatability or voluntary feed consumption. Similar feed intake among treatments suggests that the improvements in growth performance observed in supplemented ducks were not attributable to increased nutrient intake, but rather to more efficient utilization of consumed nutrients. The encapsulation process may have preserved the stability of bioactive compounds present in beetroot waste, allowing their gradual release within the gastrointestinal tract without adversely affecting feed acceptability. Comparable findings have been reported in poultry fed phytogenic feed additives, where growth responses occurred despite unchanged feed consumption, indicating improvements in digestive efficiency rather than increased feed intake (Biswas et al 2024; Aminullah et al 2025).

Figure 1. Effects of encapsulated beetroot waste on body weight gain of tegal ducks	Figure 2. Effects of encapsulated beetroot waste on feed convertion ratio of tegal ducks

Body weight gain was significantly increased by encapsulated beetroot waste supplementation (p<0.05), with both Brw0.25 and Brw0.50 producing higher gains than the control group. The improvement in growth performance appears to be closely associated with the enhanced intestinal environment observed in Table 2. Ducks receiving encapsulated beetroot waste exhibited higher populations of lactic acid bacteria together with greater villus height and villus height-to-crypt depth ratios throughout the small intestine. Increased villus height enlarges the absorptive surface area available for nutrient uptake, whereas a higher villus height-to-crypt depth ratio reflects a more mature and functionally efficient intestinal mucosa. These morphological adaptations may facilitate improved digestion and absorption of dietary nutrients, thereby supporting greater tissue accretion and body weight gain (Abdelli et al 2021; Obianwuna et al 2024).

The simultaneous increase in beneficial intestinal bacteria and improvement in intestinal morphology suggests a positive interaction between microbial activity and gut development. Lactic acid bacteria produce organic acids and other metabolites that contribute to intestinal health by creating favorable conditions for epithelial maintenance and nutrient absorption. The higher LAB counts observed in Brw0.25 and Brw0.50 may therefore have contributed to the enhanced villus development recorded in the duodenum, jejunum and ileum. Similar relationships between beneficial microbiota, improved intestinal morphology and enhanced growth performance have been reported in ducks and broiler chickens receiving plant-derived functional feed additives rich in polyphenols and antioxidant compounds (Tian et al 2025; Khomayezi and Adewole 2022).

Taken together, the absence of changes in feed intake and the significant increase in body weight gain indicate that encapsulated beetroot waste improved growth primarily through enhanced gastrointestinal functionality rather than through increased feed consumption. This interpretation is supported by the concurrent improvements in intestinal microbial balance and absorptive structures observed in the supplemented groups.

Carcass percentage was significantly affected by dietary treatment, with ducks receiving 0.25% encapsulated beetroot waste exhibiting the highest carcass yield. Improved carcass percentage may reflect more efficient nutrient partitioning toward muscle deposition as a consequence of enhanced digestive efficiency and nutrient utilization. Similar responses have been reported in poultry supplemented with phytogenic feed additives, where improvements in carcass yield were associated with better gut health and nutrient digestibility (Khomayezi and Adewole 2022; Obianwuna et al 2024).

Interestingly, increasing supplementation from 0.25% to 0.5% did not result in further improvements in carcass percentage despite favorable effects on intestinal microbiota and morphology. This finding suggests that moderate supplementation may provide the optimal balance between intestinal stimulation and productive performance. Higher concentrations of plant bioactive compounds may induce physiological adaptation without proportional improvements in nutrient deposition (Obianwuna et al 2024).

The present findings suggest a sequential relationship between gut microbial modulation and productive performance. Increased LAB populations likely improved intestinal health and contributed to enhanced villus development, resulting in greater absorptive capacity. Improved intestinal morphology may have enhanced nutrient absorption capacity, which could partly explain the better growth performance observed in supplemented ducks. These results indicate that the beneficial effects of encapsulated beetroot waste are primarily mediated through improvements in gastrointestinal functionality and nutrient utilization efficiency. Overall, the results demonstrate that encapsulated beetroot waste acts as a functional feed additive capable of improving gut microbial balance, intestinal morphology, feed efficiency and carcass yield in Tegal ducks. The beneficial effects observed at the 0.25% supplementation level indicate that moderate inclusion of encapsulated beetroot waste may represent the most efficient strategy for enhancing productivity while supporting sustainable utilization of agro-industrial by-products (Obianwuna et al 2024).

Conclusion

Supplementation of encapsulated beetroot waste at 0.25–0.50% increased lactic acid bacteria populations, improved intestinal morphology, optimized body weight gain, numerically improved feed conversion ratio and increased carcass percentage in Tegal ducks.

Acknowledgments

The authors gratefully acknowledge the Directorate of Research, Technology and Community Service (DRTPM), Directorate General of Higher Education, Research and Technology, Ministry of Education, Culture, Research and Technology of the Republic of Indonesia, for financial support through the Fundamental Research Scheme (Penelitian Fundamental) 2025.

References

Abdelli N, Solà-Oriol D and Pérez J F 2021 Phytogenic feed additives in poultry: achievements, prospective and challenges. Animals, 11(12): 3471. https://doi.org/10.3390/ani11123471

Ahmed M, Das K, Hossen M, Ataher M S, Momu J M, Aktaruzzaman M, Talha M H, Taher A, Mamun M A, Sarkar S, Mahfuz S 2026 Dietary inclusion of beetroot (Beta vulgaris): impacts on egg production, egg quality and physiological status of commercial laying hens. Veterinary and Animal Science, 31: 100559. 10.1016/j.vas.2025.100559

Aminullah N, Mostamand A, Zahir A, Mahaq O and Azizi M N 2025 Phytogenic feed additives as alternatives to antibiotics in poultry production: A review. Veterinary World, 18(1): 141. https://doi.org/10.14202/vetworld.2025.141-154

Awad W A, Ghareeb K and Böhm J 2008 Intestinal structure and function of broiler chickens on diets supplemented with a synbiotic containing Enterococcus faecium and oligosaccharides. International Journal of Molecular Sciences, 10: 2205–2216. https://doi.org/10.3390/ijms9112205

Biswas S, Ahn J M and Kim I H 2024 Assessing the potential of phytogenic feed additives: A comprehensive review on their effectiveness as a potent dietary enhancement for nonruminant in swine and poultry. Journal of animal physiology and animal nutrition, 108(3): 711-723. https://doi.org/10.1111/jpn.13922

Cappuccino J G and Welsh C T 2017 Microbiology: A Laboratory Manual. 11th Edition. Pearson Education, New York.

Das Q, Islam M R, Lepp D, Tang J, Yin X, Mats L, Liu H, Ross K, Kennes Y M, Yacini H, Warriner K, Marcone M F and Diarra M S 2020 Gut microbiota, blood metabolites and spleen immunity in broiler chickens fed berry pomaces and phenolic-enriched extractives. Frontiers in Veterinary Science, 7: 150. https://doi.org/10.3389/fvets.2020.00150

Khomayezi R and Adewole D 2022 Probiotics, prebiotics and synbiotics: an overview of their delivery routes and effects on growth and health of broiler chickens. World’s Poultry Science Journal, 78(1), 57–81. https://doi.org/10.1080/00439339.2022.1988804

Mangisah I, Suthama N and Rizqiati H 2020 Feeding combination of Lactobacillus casei and extracts of dahlia tuber or garlic on intestinal bacteria, nutrients digestibility and performance of broiler chickens. Jurnal Ilmu-Ilmu Peternakan, 30(2):158–166. https://doi.org/10.21776/ub.jiip.2020.030.02.08

Marcillo-Parra V, Tupuna-Yerovi D S, González Z, Ruales J 2021 Encapsulation of Bioactive compounds from fruit and vegetable by-products for food application—A Review. Trends in Food Science & Technology, 116: 11–23. https://doi.org/10.1016/j.tifs.2021.07.009

Obianwuna U E, Chang X, Oleforuh-Okoleh V U, Onu P N, Zhang H, Qiu K and Wu S 2024 Phytobiotics in poultry: revolutionizing broiler chicken nutrition with plant-derived gut health enhancers. Journal of animal science and biotechnology, 15(1): 169. https://doi.org/10.1186/s40104-024-01101-9

Qazi H J, Ye A, Acevedo-Fani A and Singh H 2025 Delivery of encapsulated bioactive compounds within food matrices to the digestive tract: recent trends and future perspectives. Critical reviews in food science and nutrition, 65(15): 2921-2942. https://doi.org/10.1080/10408398.2024.2353366

Stoica F, Râpeanu G, Rațu RN, Stănciuc N, Croitoru C, Țopa D and Jităreanu G 2025 Red beetroot and its by-products: A comprehensive review of phytochemicals, extraction methods, health benefits and applications. Agriculture, 15(3): 270. https://doi.org/10.3390/agriculture15030270

Tian Y, Liu X, Chen L, Zeng T, Gu T, Xu W, Ren J and Lu L 2025 Dietary resveratrol alleviates liver and intestinal injury in ducks under cage rearing system. PoultryScience, 104(8): 105330. https://doi.org/10.1016/j.psj.2025.105330