Effect of feeding sun-dried azolla (Azolla pinnata) on carcass characteristics, gut health and meat quality of broiler chicks

Introduction

The poultry industry plays a vital role in meeting the increasing global demand for highquality animal protein due to its rapid growth rate, efficient feed conversion and relatively low production cost. Broiler meat, in particular, is widely accepted because of its high nutritional value, tenderness and affordability. However, the rising cost of conventional feed ingredients such as soybean meal and maize has posed a significant challenge to sustainable poultry production. This has necessitated the exploration of alternative, cost-effective and nutritionally rich feed resources that can partially replace conventional feed ingredients without compromising productivity or meat quality. In recent years, the use of unconventional feed resources, especially aquatic plants, has gained considerable attention. Among these, Azolla pinnata, a floating fern belonging to the family Azollaceae, has emerged as a promising feed supplement due to its high protein content, essential amino acids, vitamins, minerals and bioactive compounds. It also contains symbiotic cyanobacteria (Anabaena azollae), which contribute to its high nitrogen-fixing capacity and nutritional value. Due to these characteristics, Azolla has been widely studied as a sustainable and eco-friendly feed ingredient in livestock and poultry nutrition (Mishra et al., 2016) [10] . Sun-drying of Azolla is an effective method to enhance its shelf life and facilitate its incorporation into poultry diets. The drying process reduces moisture content while preserving most of its nutrients, making it easier to handle, store and mix with conventional feed. Previous studies have reported that inclusion of sun-dried Azolla in broiler diets can improve growth performance, feed efficiency and carcass traits when used at optimal levels (Kumar et al., 2021; Samad et al., 2020) [8,18] . Abdelatty et al. (2021) [1] also reported that Azolla supplementation enhances muscle development and carcass yield due to its high digestibility and protein quality. Carcass characteristics are important indicators of the economic value of broiler production, as they directly reflect the quantity and quality of edible meat. Parameters such as dressed weight, eviscerated weight and distribution of carcass cuts provide valuable insights into the efficiency of nutrient utilization and muscle deposition. Several researchers have reported improvements in carcass yield with Azolla supplementation, particularly at moderate inclusion levels (Ara et al., 2015; Rathod et al., 2013) [3,7] . In addition to carcass traits, gut health plays a crucial role in determining the overall performance and productivity of broiler chickens. A healthy gastrointestinal tract ensures efficient digestion, nutrient absorption and microbial balance. Dietary interventions, including the use of natural feed additives like Azolla, can influence gut morphology, enzyme activity and microbial populations. Studies have shown that Azolla supplementation can improve gut health by enhancing digestive efficiency and maintaining a favorable intestinal environment (Shamna et al., 2013; Olugbemi et al., 2010) [19,13] . Meat quality is another critical aspect influencing consumer acceptance and market value. Among various quality parameters, meat pH is considered a key indicator as it affects color, tenderness, water-holding capacity and shelf life. Dietary factors play a significant role in influencing postmortem muscle metabolism and pH decline. Natural feed ingredients rich in antioxidants, such as Azolla, may help improve meat quality by reducing oxidative stress and enhancing muscle energy metabolism (Sujatha et al., 2013; Thavasi et al., 2020) [21,22] . Despite the recognized nutritional potential of Azolla, there is still limited information on the comprehensive effects of sun-dried Azolla pinnata on carcass characteristics, gut health and meat quality in broiler chickens, particularly under practical feeding conditions. Therefore, the present study was undertaken to evaluate the effect of feeding sun-dried Azolla pinnata at different inclusion levels on carcass traits, gastrointestinal parameters and meat quality of broiler chicks.

Materials and methods

Experimental Site

The present study was conducted at the Poultry Unit, Department of Poultry Science, College of Veterinary and Animal Science, Rajasthan University of Veterinary and Animal Sciences (RAJUVAS), Bikaner, with laboratory analyses performed at SKRAU, Bikaner.

Experimental Design

A total of 120 unsexed, day-old commercial broiler chicks of the same hatch were randomly allotted to four treatment groups under a Completely Randomized Design for a period of 28 days (February 13 to March 12, 2025). Each treatment consisted of 30 birds with three replicates of 10 birds each. The treatments included T 1 (control; standard broiler ration), T 2 (5% replacement of standard ration with sun-dried Azolla pinnata on a dry matter basis), T 3 (10% replacement) and T 4 (15% replacement). Birds were reared under a deep litter system with sawdust bedding and provided pre-starter (0-7 days), starter (8-21 days) and finisher (22-28 days) diets. Feed and water were offered ad libitum throughout the study period. All the necessary routine management practices and the recommended vaccinations were strictly observed throughout the period of 28 days which the study lasted.

Carcass and Organs Weight Determination

At the end of the experiment total 36 birds were selected at random starved for about for 12 hours before slaughter. All the birds selected for slaughter were weighed individually. Birds were slaughtered by halal method. Thereafter, flaying was done and the internal organs such as the heart, liver, gizzard, lungs, pancreas, proventriculus and intestines were collected and weighed individually to measure various carcass parameters (Dressed weight percentage, eeviscerated weight percentage, weight percentage of various carcass cuts, pH of various segments of gastrointestinal tract and pH of meat).

Proximate Composition

Proximate composition of the test ingredients was analyzed using the method of AOAC.

Statistical Analysis

Experimental data were subjected to analysis of variance "one-way ANOVA" as described by Snedecor and Chochran (2004). The significance of mean differences was tested by Duncan's New Multiple Range Test (Duncan's Range Test) as modified by Kramer.

Results and Discussion

Dressed weight percentage and eviscerated weight percentage

The present study was conducted to evaluate the effect of different levels of Azolla inclusion on carcass characteristics, organ weights and gastrointestinal parameters in broiler birds. The results obtained clearly indicate that Azolla supplementation influenced several production traits depending on the level of inclusion. The data regarding the dressed weight (%) and eviscerated weight (%) of broiler birds for the Azolla treatment are illustrated in Table 1. The carcass characteristics revealed that eviscerated weight (%) was significantly influenced (p<0.05) by dietary treatments. The highest value was observed in T 2 (68.45 ± 0.25%), followed by T 3 (67.60 ± 0.19%) and T 4 (67.07 ± 0.51%), whereas the lowest value was recorded in T 1 (66.24 ± 0.25%). The improvement in eviscerated weight in T 2 indicates better nutrient utilization and muscle deposition at 5% Azolla inclusion. These findings are in agreement with the reports of Mishra et al. (2016) [10] and Kumar et al. (2021) [8] , who observed improved carcass yield in broilers fed Azolla at moderate inclusion levels. Similarly, Abdelatty et al. (2021) [1] reported enhanced carcass traits due to the high protein content and digestibility of Azolla. However, dressed weight (%) did not differ significantly among treatments (P>0.05), although higher numerical values were recorded in T 3 (74.16 ± 0.16%), T 2 (74.12 ± 1.11%) and T 4 (74.06 ± 0.56%) compared to T 1 (72.69 ± 0.12%). This observation is consistent with the findings of Samad et al. (2020) [18] and Rathod et al. (2013) [17] , who also reported non-significant differences in dressed weight despite improvements in other carcass traits.

Weight percentage of different carcass cuts

The data regarding the weight (%) of different carcass cuts of broiler birds for the Azolla treatment is illustrated in Table 2. The distribution of carcass cuts showed that neck weight (%) was significantly higher in T 2 (4.68 ± 0.13%) compared to T 1 (3.20 ± 0.11%), with T 3 (4.36 ± 0.39%) and T 4 (3.78 ± 0.18%) showing intermediate values. This improvement in minor cuts may be attributed to better protein utilization, as also reported by Kumar al. (2021). Wing percentage was highest in T 3 (6.07 ± 0.21%) followed by T 4 (5.82 ± 0.17%), T 2 (5.73 ± 0.17%) and T 1 (5.29 ± 0.27%). This trend supports the findings of Rathod et al. (2013) and Samad et al. (2020) [18] , who observed enhanced development of specific carcass parts with increasing Azolla levels. Breast percentage did not differ significantly among treatments, ranging from 24.26 ± 0.40% (T 4 ) to 25.06 ± 0.56% (T 3 ), indicating that Azolla inclusion did not compromise the most valuable cut. Similar observations were reported by Abdelatty et al. (2021) [1] . Back percentage also remained unaffected, ranging from 11.03 ± 0.55% to 11.87 ± 0.15%. Thigh percentage increased with higher inclusion levels, reaching 11.73 ± 0.30% in T 4 compared to 10.87 ± 0.22% in T 1 , which is in line with findings by Kumar et al. (2018) [6] and Joysowal et al. (2018) [4] , who reported improved leg muscle development. Conversely, drumstick percentage decreased significantly in T 3 (9.68 ± 0.55%) and T 4 (9.61 ± 0.39%) compared to T 1 (11.07 ± 0.26%) and T 2 (10.84 ± 0.89%), suggesting a shift in nutrient partitioning, as also noted by Paudel et al. (2015) [15] .

The data regarding the weight (%) of giblets including heart, liver and gizzard of broiler birds for the azolla treatment is illustrated in Table 3. The giblet characteristics indicated that liver weight (%) did not differ significantly among treatments, with values ranging from 1.79 ± 0.12% (T 4 ) to 2.03 ± 0.07% (T 3 ). This suggests that Azolla inclusion did not adversely affect liver function, which agrees with the findings of Ara et al. (2015). Heart weight (%) was significantly lower in T 2 (0.46 ± 0.01%) compared to T 1 (0.56 ± 0.02%), while T 3 (0.52 ± 0.03%) and T 4 (0.53 ± 0.02%) showed intermediate values. This reduction may indicate improved metabolic efficiency, as suggested by Rathod et al. (2013) and Sharma et al. (2020). Gizzard weight (%) was significantly higher in T 2 (1.92 ± 0.06%), followed by T 3 (1.75 ± 0.12%), T 1 (1.68 ± 0.06%) and T 4 (1.63 ± 0.04%). The increased gizzard weight may be attributed to the fibrous nature of Azolla, which stimulates muscular activity, as reported by Parthasarathy et al. (2002) [14] and Naghshi et al. (2014) [12] . Total giblet weight did not differ significantly among treatments, which is consistent with Kumar et al. (2018) [6] and Samad et al. (2020) [18] .

The data regarding the weight (%) of overall visceral inedible including the intestine, lungs, proventriculus, pancreas, kidney, spleen and crop of broiler birds for the Azolla treatment is illustrated in Table 4. The analysis of visceral organs revealed that intestinal weight (%) was lowest in T 2 (3.54 ± 0.09%) and highest in T 4 (4.55 ± 0.11%), indicating improved digestive efficiency at moderate inclusion levels and increased gut mass at higher levels. Similar findings were reported by Abdelatty et al. (2021) [1] and Shamna et al. (2013) [19] . Pancreas weight (%) was highest in T 3 (0.42 ± 0.01%), followed by T 2 (0.40 ± 0.05%), suggesting increased digestive enzyme activity, which aligns with Rathod et al. (2013) [17] . Proventriculus weight (%) was also higher in T 3 (0.44 ± 0.03%) and T 4 (0.43 ± 0.03%) compared to T 1 (0.34 ± 0.02%), supporting enhanced digestive function as reported by Parthasarathy et al. (2002) [14] . Kidney weight (%) was lowest in T 2 (0.35 ± 0.02%), indicating reduced metabolic load, which agrees with Kumar et al. (2018) [6] . The weights of lungs, spleen and crop did not differ significantly among treatments, confirming the safety of Azolla inclusion, as also observed by Joysowal et al. (2018) [4] and Samad et al. (2020) [18] .

The data regarding the weight (%) of overall external offal including the head, shanks, feathers and blood of broiler birds for the azolla treatment is illustrated in Table 5. The external offal characteristics showed that feather weight (%) was significantly higher in T 2 (14.54 ± 0.23%) compared to T 1 (13.62 ± 0.36%), T 3 (13.43 ± 0.18%) and T 4 (13.58 ± 0.25%).

This may be due to improved protein and micronutrient utilization, as reported by Abdelatty et al. (2021) [1] and Sharma et al. (2020). Blood weight (%) was highest in T 1 (4.02 ± 0.12%) and significantly reduced in T 2 (2.77 ± 0.31%), T 3 (2.81 ± 0.08%) and T 4 (2.50 ± 0.17%), which may indicate improved metabolic efficiency, as suggested by Rathod et al. (2013). Shank weight (%) was significantly higher in T 4 (6.21 ± 0.29%) and T 3 (6.05 ± 0.17%) compared to T 2 (4.87 ± 0.54%), indicating better skeletal development due to the mineral-rich nature of Azolla. Similar results were reported by Ara et al. (2015). Head weight and total external offal did not differ significantly among treatments, which is consistent with Mishra et al. (2016) [10] .

pH of Various Segments of Gastrointestinal Tract

The data regarding pH of various segments of gastrointestinal tract recorded in this experiment has been presented in Table 6. The pH of different segments of the gastrointestinal tract indicated that crop pH (4.06-4.14) and proventriculus pH (3.51-3.82) were not significantly affected by treatments, which is in agreement with Ahmed et al. (2023) [2] and Muzammil et al. (2018) [11] . However, gizzard pH was significantly higher in T 2 (3.53 ± 0.11%) and T 3 (3.49 ± 0.09%) compared to T 4 (3.19 ± 0.08%), possibly due to the buffering effect of Azolla, as suggested by Qin et al. (2020) [16] . Jejunum pH was highest in T 3 (6.29 ± 0.17%), while ileum pH was highest in T 2 (6.99 ± 0.12%), indicating improved microbial activity and nutrient absorption. Similar observations were reported by Olugbemi et al. (2010) [13] . Caecum pH did not differ significantly among treatments, which agrees with Parthasarathy et al. (2002) [14] . In azolla inclusion particularly at 5 to 10% influenced pH in specific gut segments like the gizzard, jejunum and ileum which may contribute to improved digestion and gut health. These effects support the inclusion of azolla as a feed in broiler nutrition with potential implications for enhancing nutrient utilization and promoting gut microbial balance.

pH of meat

The data regarding pH of meat recorded in this experiment has been presented in Table 7. The meat pH showed significant variation among treatments, with the lowest values recorded in T 2 (5.49 ± 0.90%) and T 3 (5.56 ± 0.10%), while higher values were observed in T 1 (6.27 ± 0.03%) and T 4 (6.49 ± 0.08%). The lower pH in T 2 and T 3 indicates better postmortem glycolysis and improved meat quality, which is in agreement with Thavasi et al. (2020) [22] . Higher pH values in T 1 and T 4 may be associated with slower glycogen depletion, as reported by Mir et al. (2017) [9] and Kannan et al. (2001) [5] . Additionally, the antioxidant properties of Azolla may contribute to improved muscle metabolism, as suggested by Sujatha et al. (2013) [21] . Overall, the findings of the present study clearly demonstrate that Azolla inclusion at 5% (T 2 ) is optimal for improving carcass traits, organ development, gut health and meat quality in broiler chickens. Higher inclusion levels showed variable effects, indicating that moderate supplementation is more beneficial for achieving efficient production performance.

Conclusion

The inclusion of sun-dried Azolla pinnata at 5-10% level in broiler diets significantly improves growth performance, carcass characteristics, digestive efficiency and meat quality without adverse effects on organ development. The 5% inclusion level was found to be optimal for maximizing productivity and profitability. Azolla can be recommended as a sustainable, cost-effective alternative feed ingredient in broiler production systems.

Acknowledgement

AcknowledgmentThe authors are grateful to the Department of Poultry Science, RAJUVAS, Bikaner and SKRAU, Bikaner for providing necessary facilities to conduct this study.

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