Dr. Farhana Sharmin

Roselle/Mesta (Hibiscus sabdariffa L.) and Kenaf (Hibiscus cannabinus L.) are important and versatile plants belonging to the family Malvaceae. Both species are fast-growing and capable of producing high biomass yields. While kenaf is primarily cultivated for fiber production and roselle is grown for food, medicinal, and other multipurpose uses, their leaves can also be considered as a promising green feed resource.

Although considerable number of research works have been conducted in Bangladesh on fiber production from mesta (roselle) and kenaf, comparatively limited research has focused on the use of their leaves as functional feed ingredients in poultry diets. The leaves of roselle and kenaf contain crude protein, minerals, vitamins, dietary fiber, and a range of biologically active phytochemicals. Therefore, their potential utilization in poultry diets is scientifically important from the perspectives of nutrition, animal health, productivity, and sustainable production.

Potential of Roselle and Kenaf Leaves in Poultry Feed

Roselle and kenaf leaves contain phenolic compounds, flavonoids, and other antioxidant phytochemicals that have attracted increasing interest in poultry nutrition. These bioactive compounds may contribute to the regulation of oxidative stress through free-radical scavenging activity. Excessive oxidative stress in poultry is associated with impaired immune function, reduced production efficiency, and deterioration of meat and egg quality. Therefore, the inclusion of plant-derived antioxidants in poultry diets may represent a promising natural nutritional strategy. However, the potential use of roselle and kenaf leaves in poultry feed should not be evaluated solely on the basis of their nutritional value. Dietary fiber, secondary metabolites, and anti-nutritional factors must also be considered. Excessive dietary fiber may reduce nutrient digestibility and absorption and consequently impair feed utilization efficiency. Therefore, determining the appropriate harvesting stage, processing method, and dietary inclusion level is essential.

Important Bioactive and Anti-Nutritional Compounds Present in the Leaves

1. Tannins

Tannins can form complexes with proteins, which may reduce protein digestibility and amino acid availability. However, low concentrations of tannins are not necessarily harmful and may provide antioxidant and other biological activities at appropriate levels. Therefore, determining the tannin concentration in the leaves and the safe dietary inclusion level is important.

2. Phytate or Phytic Acid

Phytate can form complexes with several minerals, particularly phosphorus, calcium, iron, and zinc, thereby reducing their bioavailability. Where necessary, the adverse effects of phytate may be reduced through phytase supplementation or appropriate processing techniques.

3. Oxalate

Oxalate can form insoluble complexes with calcium and may consequently reduce calcium utilization. However, the actual dietary risk depends on the concentration of oxalate in the leaves and the level at which the leaves are included in poultry diets.

4. Saponins

Saponins possess several biological activities. At appropriate concentrations, they may contribute to cholesterol metabolism, antioxidant activity, and antimicrobial effects. However, excessive amounts of saponins may negatively affect feed palatability, digestion, and nutrient utilization.

5. Phenolic Compounds and Flavonoids

Phenolic compounds and flavonoids are important bioactive secondary metabolites. They may exhibit antioxidant activity and potentially influence oxidative status, immune response, and meat quality in poultry.

Therefore, roselle and kenaf leaves should not be considered merely as conventional green feed materials; these could be explored as potential functional feed ingredients.

Research Activities in Bangladesh

Bangladesh Jute Research Institute (BJRI), through its Post‑Harvest Processing Department under the Fiber Quality Improvement Division, in collaboration with Bangladesh Livestock Research Institute (BLRI) to investigate the bioactive compounds of roselle and kenaf leaves. This project is supported by the Krishi Gobeshona Foundation (KGF), this pioneering research seeks to harness the nutritional and functional benefits of these fiber crops for poultry feed technology innovation, promoting healthier livestock and advancing sustainable agriculture in Bangladesh.

The research includes cultivation of roselle and kenaf, leaf production, harvesting at a specific growth stage, drying, preservation, and evaluation of their suitability for poultry feed. Nutritional composition and phytochemical profiles of the leaves are being analyzed at different stages of the research. Experimental cultivation of roselle and kenaf is being conducted at: Jute Agriculture Experimental Station, Manikgonj; Jute Research Regional Station, Rangpur; and regional station of Bangladesh Livestock Research Institute, Saidpur.

Leaves are being harvested at approximately 60 days of age, followed by appropriate drying and storage. Subsequently, the leaves are incorporated into poultry diets at predetermined levels to evaluate their nutritional value, feed utilization efficiency, and potential functional effects.

 

Nutritional and Bioactive Profile of the Leaves

To determine the true potential of roselle and kenaf leaves as feed ingredients, the following characteristics are important to analyze: Crude protein; Crude fiber; Ether extract; Ash; Metabolizable energy; Amino acid profile; Mineral composition; Phenolic compounds; Flavonoids; Antioxidant activity; Tannins; Phytate; Oxalate; and Saponins. Such analyses can provide a scientific basis for determining the nutritional value, safety, and suitability of roselle and kenaf leaves as functional feed ingredients.

Evaluation of Effectiveness in Poultry Trials

The potential benefits of roselle and kenaf leaves should not be evaluated only in terms of growth performance. Their effects at different dietary inclusion levels should be assessed through a range of parameters:

Feed intake → Body weight gain → Feed conversion ratio → Nutrient digestibility → Antioxidant status → Meat quality

In particular, in broiler chickens, we analysis of the following parameters, this can provide valuable information about the potential functional effects of bioactive compounds present in the leaves: Proximate composition of meat; Amino acid profile; Fatty acid composition; Cholesterol content; Lipid oxidation, particularly TBARS; and Meat quality and storage stability.

These parameters can help establish whether the bioactive compounds present in roselle and kenaf leaves contribute to improvements in the nutritional and functional quality of poultry meat.

Potential for Sustainable Poultry Production

Bangladesh's rapidly expanding poultry industry plays an important role in meeting the country's demand for animal protein. However, feed represents one of the major components of poultry production costs (about 65 to 70%). Dependence on conventional feed ingredients such as maize and soybean meal, together with fluctuations in their price and availability, can significantly influence poultry production costs.

Therefore, identifying locally available, nutritious, safe, and relatively low-cost plant-based feed resources is highly important. Roselle and kenaf leaves can be produced locally, their value-added utilization in poultry feed may contribute to:

1. Reducing dependence on conventional feed ingredients;
2. Controlling the costs of feed and feed ingredients;
3. Optimizing the utilization of local agricultural resources;
4. Adding value to agricultural biomass;
5. Promoting environmentally sustainable production systems; and
6. Establishing an effective resource linkage between the agricultural and poultry sectors.

 

Connection with the Circular Bioeconomy

The dietary utilization of roselle and kenaf leaves is also closely aligned with the concept of a circular bioeconomy. Instead of considering leaves as low-value or waste biomass generated during fiber production, they can potentially be converted into value-added functional feed ingredients through appropriate harvesting, processing, and dietary inclusion strategies. In this way, additional economic value can be generated from the same agricultural resource while simultaneously reducing biomass waste and improving resource-use efficiency. Thus, roselle and kenaf leaves may contribute to a more integrated production system in which fiber production and livestock nutrition are interconnected, creating opportunities for agricultural waste reduction, value addition, income generation, and sustainable poultry production.

Concluding remarks

The nutritional composition, phytochemical profile, antioxidant potential, feed utilization efficiency, and effects on poultry performance of roselle and kenaf leaves are currently being scientifically evaluated. In particular, determining the safety, nutritional value, functional efficacy, and anti-nutritional effects of these leaves at different dietary inclusion levels is essential for establishing their potential as locally available and sustainable functional feed resources in Bangladesh. With appropriate harvesting stage, processing technology, and dietary inclusion level, roselle and kenaf leaves could become a locally available, nutrient-rich, bioactive, and sustainable alternative feed resource for poultry nutrition. Their utilization may simultaneously contribute to reducing poultry production costs, adding value to agricultural biomass, improving the utilization of local resources, and developing an environmentally friendly circular production system. Therefore, roselle and kenaf leaves should be considered not merely as by-products or underutilized biomass of fiber production, but as promising functional feed ingredients with potential applications in sustainable poultry nutrition and value-added agricultural production in Bangladesh.

 

Dr. Farhana Sharmin

Senior Scientific Officer

Post-Harvest Processing Department

Fiber Quality Improvement Division

Bangladesh Jute Research Institute (BJRI)