Introduction

Poultry feeding is an important factor in poultry production; the improvement of poultry production is highly depended on synergy between science and practice. By use of modern technology and nutrition knowledge, production of fattening chicken highly increased in the whole world in last 30 years¹.

Dietary fibre is traditionally considered as an anti-nutritional factor². However, moderate amounts of fibre may promote organ development, enzyme production, and nutrient digestibility in poultry. Fibrous feed ingredients have been used in diets of ruminant animals; however, has encouraged researchers to seek a greater understanding of the role of fibrous feedstuffs in diets for non-ruminant livestock³. The use of high dietary fibre feed ingredients in poultry diet has generally been discouraged due to the negative effects exerted on nutrient utilization and performance such as their depression of diet digestibility, and decrease in body weight gain and worsen feed conversion⁴. However, some types of fibre and fibre sources do not exert such negative effects on nutrient digestibility. Some of these effects result from better gizzard function, with an increase in the gastro duodenal reflux that promotes the contact between nutrients and digestive enzymes⁵.

Fibre is a nutritionally, chemically and physically heterogeneous material. It may be divided into soluble fibres which are viscous and fermentable, and insoluble fibres, which are less viscous and fermentable. Both soluble and insoluble fibres have various roles in the digestion and absorption processes in the gastrointestinal tract⁶. Fibre in feed ingredients may affect caecal microbial population and nutrient digestibility. Interactions of these effects can affect bird performance. Thus, nutritionists are faced with a challenge of formulating diets with the available feed ingredients, but also having to mitigate the resulting diet effects to achieve optimum bird production⁷. Wheat bran and cellulose, which are categorized as insoluble fibres, elevate faeces weight and faecal bulk and decrease intestinal transit time in non-ruminant). Low apparent metabolizable energy (AME), impaired nutrient absorption and increased incidence of wet droppings may occur due to increase gut viscosity related to feeding soluble non starch polysaccharides (NSP)^6-8. Adding fibrous feedstuffs dilutes the diet and may improve the motility and function of the gastrointestinal tract (GIT). Studies by⁸ reported that fibre inclusion diet did not compromise carcass characteristics and sensory evaluation in broiler chickens. The beneficial effects of fibre were also shown to be related to decreasing gizzard pH, which was accompanied by enhanced nutrient utilization to support and/or increase growth⁹. Determination of the required amount of energy and protein in feedstuff is also probably the most important decision to be made when it comes to feed formulation for broiler. Hence, formulation of animal feed must take into consideration the nutrient density with energy as the prime factor of the particular feed to facilitate production. The performance of broiler chicks was evaluated by¹⁰ that protein level of 20 % and energy level of 3200 kcal kg^-1 diet may be recommended for finishing broiler chickens. Increasing dietary energy level will increase weight gain and also improve feed conversion^10,11.

The attention now is being focused on cheap but suitable alternative feedstuffs. Utilization of cheaper unconventional or certain locally available feed ingredients in place of conventional one has been widely practiced to mitigate this problem. However, the use of unconventional feedstuff for efficient poultry production is limited due to presence of indigestible components like fibre non-starch polysaccharides¹². Many forms of residues are produced from wood processing plants. For instance, residues from wood processing plants (the shredded bark, sawdust, and shavings) frequently have no markets, but most untreated woods are quite indigestible. However, that the sawdust up to 80 g^-1 kg level of inclusion in broiler diets did not have any detrimental effect on weight gain¹³.

Since sawdust is abundant and available throughout the year in many developing countries, the utilization of sawdust will reduce the cost of production.

The physiological and practical implications of the link between crude fibre and energy intake under iso-protein must then be considered when the dietary requirements for either nutrient are assessed. Moreover, there is a lack of sufficient information about the effect of dietary energy density and crude fibre level on the carcass characteristics and sensory evaluation of broiler chickens¹⁴. Therefore, the aim of this study was to study the effect of the inclusion of wheat bran, rice bran, and brewers dried grain (BDG) in the formation of feed for broiler chicken on their growth performance, carcass and sensory quality.

The reason for this study was to address the problem of competition for nutrients between human and broiler birds, which was the reason for high cost of poultry feeds. Global competition for high standard feed-food resources between man and livestock is a concerning problem. There is need to propose alternative ingredients, less sought after in the human diet, that could be used in broiler diet.

Materials and methods

Housing and study location. The study was carried out at the Teaching and Research Farm of the Department of Animal Production and Health, Faculty of Agriculture, Federal University Oye-Ekiti, Ekiti State, Nigeria. The location is within longitude 5.5145^oE and latitude 7.7983^oN and at an elevation of 570 m above sea level. The climate of the study area is typically tropical with relative humidity ranging from 57-92 % and mean average daily temperature of 68-90^o F.

Experimental materials and duration of study. One thousand (1000) day old broiler chicks were used for this study. A total number of one thousand and fifty (1050) day old chicks were purchased from CHI farms in Ibadan, Oyo state. The birds were assigned randomly to their treatments. There were four treatments, with three (3) replications per treatment. Twelve (250) birds were randomly assigned to each treatment. The experiment lasted for a period of eight (8) weeks. Experiment was done in year 2021.

Experimental birds and management. Washing, cleaning and disinfection of the pen with Izal and formalin was done five (5) days prior to the arrival of the birds. Wood shavings were used as beddings for the birds, using this helped to absorb faecal water and to prevent Coccidiosis. The bedding was changed twice weekly. The chicken was raised on deep litter system throughout the experimental period. Coal pot and charcoal were used as source of heat for the chicks during the brooding period.

Antibiotics and vitamins were administered to the birds except on the days of vaccination. Vaccine against Infectious Bursal disease (using Attenuated Infectious Bursal Disease Vaccine) was administered on the first (7th day) and third week (21st day) of life respectively. Vaccine against Newcastle disease using (Lasota vaccine) was administered on the second week (14th day) and fourth week (28th day) respectively. All the vaccines were administered orally.

The birds were fed ad-libitum with broiler starter diet in the first two weeks. Water was given ad-libitum throughout the experiment.

Experimental diet. The experimental diet was formulated for both starter and finisher phase. The major source of energy for the diet was maize and the major source of crude protein was soya bean meal. The control diet T₁ was formulated without dietary fibre, T₂ was formulated with wheat bran as the source of fibre, T₃ was formulated with rice bran as the source of fibre and T₄ was formulated with brewers dried grain (BDG) as the source of fibre.

Data collection. Feed was weighed daily before given to the birds so also the left-over every morning to determine the feed intake. The birds were weighed weekly and the data were recorded. Weighing was done by using a sensitive weighing scale.

Bird Management and Biosecurity. Prior to the birds' arrival, the pen was thoroughly cleaned and disinfected using Izal and formalin. Biosecurity measures were strictly implemented throughout the study period. Bedding was applied to absorb moisture and minimize coccidiosis risk.

Vaccination schedules were as follows: i) Infectious Bursal Disease Vaccine (attenuated) was administered orally on day 7 and day 21. ii) Newcastle Disease Vaccine (LaSota strain) was administered orally on day 14 and day 28.

Prophylactic antibiotics and multivitamins were administered except on vaccination days. Birds were provided with clean water and fed ad libitum throughout the trial.

Carcass and Sensory Evaluation. At the end of the experiment, 12 birds per treatment (4 birds per replicate, randomly selected) were humanely slaughtered following institutional ethical guidelines. Slaughtering was done according to standard halal procedures. Carcass traits such as dressing percentage, organ weights, and abdominal fat were measured.

For sensory evaluation, cooked breast meat samples from each treatment were served to a panel of 10 trained evaluators who were familiar with poultry meat quality attributes. Panelists assessed flavor, tenderness, juiciness, and overall acceptability using a 9-point hedonic scale.

Ethical Considerations. All animal handling procedures were conducted following ethical standards approved by the Animal Ethics Committee of the Federal University Oye-Ekiti. Humane slaughter practices were observed, and efforts were made to minimize animal discomfort throughout the study.

Statistical analysis. The experimental design used for this study was completely randomized design (CRD). Data generated was subjected to the analysis of variance (ANOVA) according to (SAS) at p=0.05. Means were separated using Turkey honesty significant difference test. The descriptive statistics used was cross tabulation and percentage frequency.

Statistical model.

Y_ij - General Observation, U - General Mean. D_i - Effect of the dietary treatment. E_ij - Random residual error

Results

Discussion

Growth Performance. The broiler chickens is a key indicator of the nutritional effectiveness of various feed ingredients. In this study, the inclusion of rice bran significantly improved growth parameters, such as final weight, weight gain, and feed conversion ratio. As shown in Table 1, broilers fed rice bran (T₃) exhibited the highest final weight (2600 g) and weight gain (2554 g), which was significantly higher than the BDG (T₄) and control (T₁) groups. This result is consistent that fermented rice bran enhanced growth performance in broilers by improving the bioavailability of phosphorus¹⁵. Similarly, fiber-rich ingredients like rice bran positively impacted broiler digestibility, leading to enhanced nutrient absorption and growth¹⁶.

In contrast, BDG (T₄) resulted in the lowest growth performance, with a final weight of 2400 g. The lower growth performance in the BDG group could be attributed to the relatively high fiber content of BDG¹⁷, can reduce nutrient digestibility in poultry, also pointed out that although BDG is a valuable source of fiber, its lower nutrient digestibility compared to rice bran can limit its efficacy in promoting growth¹⁸.

Carcass characteristics and internal organ weights. Carcass characteristics are crucial for assessing the quality of meat produced in broilers. Table 2 reveals that there were no significant differences in the carcass yield, breast muscle, or thigh muscle weights between the rice bran and control groups. However, a noticeable increase in gizzard weight was observed in the rice bran-fed birds (T₃), suggesting that rice bran’s high fiber content promotes greater gizzard development. This observation aligns with the findings of, who suggested that higher fiber intake can stimulate gizzard growth, as the organ plays a critical role in breaking down fibrous material, thereby aiding digestion^19-21.

Although rice bran enhanced the gizzard size, BDG did not show significant effects on gizzard weight or overall carcass traits. This may be due to the fact that BDG, despite being fiber-rich, does not offer the same nutritional benefits as rice bran^22,23. Rice bran’s balanced nutrient profile likely contributed to better overall carcass composition.

Meat quality and sensory evaluation. The sensory evaluation of meat quality is essential for consumer preference and marketability. Table 3 summarizes the sensory scores for meat from broilers fed different diets. The BDG group (T₄) scored higher in terms of taste, aroma, juiciness, and tenderness compared to the rice bran group (T₃). This result mirrors the findings of¹⁹, who reported that BDG inclusion improved meat quality attributes like flavor and juiciness in geese. Additionally, processing methods, such as extrusion, could enhance the sensory qualities of rice bran, though their effects on growth performance were less pronounced²⁰.

The favorable sensory properties of BDG-fed meat may be due to the presence of certain compounds in BDG that enhance fat metabolism, influencing flavor and moisture retention²⁴. Suggested, high-fiber ingredients like BDG can have unique effects on the palatability and texture of poultry meat, making it more appealing to consumers. However, while BDG enhanced sensory qualities, it did not show significant improvements in growth performance, suggesting that BDG is more suitable for improving meat quality than for optimizing growth.

Nutrient utilization and digestibility. The efficiency of nutrient utilization and digestibility is a critical factor influencing growth performance. Table 4 highlights that broilers fed rice bran showed better feed conversion ratios, which suggests improved nutrient utilization. This outcome is consistent, rice bran, particularly in defatted form, enhanced nutrient absorption in broilers. The increased weight gain observed in the rice bran group (T₃) can be attributed to the high digestibility of rice bran's nutrients, which are readily available to the broilers²⁵.

BDG, on the other hand, resulted in a less favorable feed conversion ratio, likely due to the reduced digestibility associated with its higher crude fiber content, out that fiber-rich ingredients like BDG may limit nutrient availability, thereby reducing overall growth performance^17,22. In contrast, rice bran’s lower fiber-to-nutrient ratio made it more effective in promoting nutrient absorption.

Impact of processing on rice bran and BDG. The processing methods applied to rice bran and BDG are significant in determining their efficacy as feed ingredients. As stabilization techniques, including heat treatment and the addition of antioxidants, can improve the nutritional quality of rice bran and enhance its stability in poultry feed^18,23. The improved stability of rice bran likely contributed to its superior performance in broiler growth and nutrient availability, as seen in this study.

In contrast, BDG typically undergoes minimal processing, which may explain its lower nutritional efficiency. Further processing or the addition of enzyme mixtures could enhance BDG's digestibility, though these factors were not evaluated in the current study. Rice bran outperformed BDG in promoting broiler growth performance and nutrient utilization^19,20,22. While BDG improved sensory qualities of meat, its high fiber content did not significantly support growth^21,24,26,27. The results of this study suggest that rice bran is an effective ingredient for enhancing both the growth and health of broilers, while BDG may be more suitable for improving meat quality^28,29. Future studies should further explore the effects of different processing methods on these ingredients to optimize their nutritional value for broiler diets.

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Notes

Author notes

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