Exploring the effects of inclusion of dietary fresh Azolla on the performance of White Pekin broiler ducks

Aim: The objective of this study was to investigate the dietary advantages of inclusion of unconventional nutrient source, i.e., Azolla in the basal diet of White Pekin broilers. Materials and Methods: All ducklings were randomly distributed into three treatment groups with three replicates each and each replicate having 12 ducklings and were reared in deep litter system. Groups were subjected to three dietary treatments such as G1: Basal diet, G2: Basal diet + 5% fresh Azolla of basal diet, G3: Basal diet + 10% fresh Azolla of basal diet. During experimental period, parameters, such as bodyweight, bodyweight gain, feed consumption,feed conversion ratio(FCR), and economic of production,wererecorded. Results: The result showed that body weights in every week, except the 5th week, did not differ significantly between groups. However, no significant difference was observed between the groups in any week in terms of absolute body weight gain and feed consumption. As regard to FCR, the 10% Azolla group (G3) showed the best feed efficiency followed by the 5% Azolla group (G2) and the control group (G1). On the basis of profit/bird or profit/kg live weight, each of the Azolla-fed group showed a higher economic efficiency than the control. Conclusion: From the experiment, it was concluded that Azollaat 5 or 10% level can be included in the diet to economize the White Pekin broiler farming, and it can be great impetus to poultry farming to include unconventional nutrient source as a dietary supplement.


Introduction
Among Indian livestock based vocations, poultry farming occupies a special position due to its enormous potential to bring about rapid economic growth with low investment. It is the most profitable enterprise responsible for employment for rural peoples [1]. It has been reported that the modern domestic White Pekin duck performs better than the modern broiler chicken in terms of weight gain and feed efficiency to the same live weight due to genetic improvement [2].
Feeding value of Azolla has been experimented by several workers in different poultry species, viz. chicken [3,4], ducks [5,6], and quails [7] with promising results in performance. Almost no literature is available on the performance of broiler duck, White Pekin, upon feeding of Azolla. The issue looks more pertinent because of the fact that both duck and Azolla are water-oriented and that Azolla is found ubiquitous in water bodies. Therefore, the proposed study, i.e. the effect of dietary fresh Azolla on the performance of White Pekin broiler ducks has been envisaged to find out the potential effect of fresh Azolla on growth performance.

Ethical approval
Experiments were carried out in accordance with the guidelines laid down by the institute Animal Ethics Committee for the use of animal subjects or that procedures were in compliance with at least the declaration of the National Institute of Health guide for care. Institute (CARI), Bhubaneswar. The ducklings were allowed an adaptationperiod of 2-week along with brooding. All ducklings were weighed and randomly distributed into three treatment groups with three replicates each and each replicate having 12 ducklings, maintaining uniformity in body weight. Ducklings were grown in deep litter system of rearing, and the experimental diets were provided as per BIS [8] specification.The experimental groups were subjected to dietary treatment on completion of 2 weeks of age. The experimental groups were as under.

Experimental diets
The ingredient and nutrient compositions of experimental rations are presented in Table-1.
The diets for White Pekin broiler ducks were prepared to meet their nutrient requirements as followed in CARI, Bhubaneswar. Experimental feed samples were analyzed for dry matter (DM), crude protein (CP), ether extract, crude fiber, nitrogen free extract (NFE), total ash and acid insoluble ash as per AOAC [9].

Cultivation and feeding of Azolla
Azolla, required for the preparation of experimental diets was cultivated in the premises of Instructional Livestock Farm Complex, as per the standard procedures [10] with little modification. Pits of size 8ft × 5ft with depths of 10ʺ were dug and spread with polythene sheets to hold the water. In each pit, 10-15 kg of sieved fertile soil was applied uniformly to a thickness of 3ʺ. 2 kg of 2-day-old cow dung was mixed with 10 L of water and poured over it. Single super phosphate was added along with cow dung slurry at a rate of 20-30g/pit. Water was allowed to stand to a depth of 10 cm in the pit. A pure culture of Azollapinnata was inoculated at 0.5-1 kg/pit. The pit was completely filled with Azolla biomass growth in about 10-15 days. About 10 g of super-phosphate and 500 g of cow dung were added once every 4 days to fertilize the pits and to maintain the production rate of 1 kg/pit every day.
After harvesting, the Azolla was rinsed with fresh water for 3-4 times. To remove excess water, it was spread over a net for 3 h. Calculated amount of fresh Azolla was offered to birds in separate containers twice daily. At the end of the day, the left over Azolla was collected and weighed.

Chemical composition of Azolla
The Azolla samples were analyzed for the chemical composition such as DM, CP, ether extract, crude fiber, NFE, total ash and acid insoluble ash, as per AOAC. Calcium was determined according to the method modified by Talapatra et al., 1940 [11]. The contents of micro minerals viz. zinc, copper, manganese and iron contents in the Azolla samples was estimated by collecting 2 g samples and digesting at 120°C using 5 ml conc. HNO 3 for 1 h using KEL digestion system, India. The digested samples were cooled, and 3 ml of 70% HClO 4 was added for further digestion at 200°C. The process continued until the contents appeared clear and colorless. The digested samples were filtered into a volumetric flask. The contents of digestion tubes were repeatedly washed with triple distilled water to obtain a complete extract of the mineral. The samples were aspirated into atomic absorption spectrophotometer (ELECO-246) to determine the micro mineral contents.

Body weight and gain in body weight
At the end of each week, the ducklings were weighed individually. Then replicate wise weekly average body weights were calculated. Absolute gains  were calculated by subtracting the initial body weight (2 nd week) from final body weights of successive weeks.

Feed consumption and calculation of feed conversion ratio(FCR)
Daily feed offered to the birds were recorded group wise. The daily group average feed consumption was calculated by subtracting the leftover feed at the next morning from the total feed supplied to the birds on the previous day. Cumulative feed consumption was calculated by adding the feed consumption from the 1 st week up to the desired week. up to a particular week Cumulative body weight gain (g) upto that week

Economics of White Pekin broiler duck production
The cost of each diet prepared during broiler duck feeding trial was arrived at by considering the prevailing prices of the constituent feed ingredients, minerals, salts and other additives. Further, by considering the expenditure on ducklings, labor, medicine, etc. to be similar for each treatment, the net profit for each treatment was calculated separately for broiler ducks under different treatments taking into account the sale price of broiler ducks. The relative cost effectiveness of each diet was thus assessed (Table-2).

Statistical analysis
Data obtained from the experiment were subjected to statistical analysis wherever required. The effects of treatments were determined by analyzing the data using one-way ANOVA followed by Duncan's multiple comparison tests. p<0.05 or <0.01 was considered statistically significant.

Result Chemical composition of Azolla
The chemical composition of Azolla is presented in Table-3.

Body weight
The weekly average body weights, for the ducks in the three groups, are presented in Table-4. Body weights in any week, except the 5 th week, did not differ significantly (p≥0.05) between groups. In the 5 th week, group G 3 showed significantly (p≤0.01) higher weights than group G 1 or G 2 , while there was no significant (p≥0.05) difference between the latter two groups.

Gain in body weight
The weekly average absolute gains in body weight for three groups of ducks are presented in Table-5. No significant (p≥0.05) difference was observed between the groups in any week.

Feed consumption
The weekly cumulative feed consumptions, for the birds in the three groups, are presented in Table-6. No significant (p≥0.05) difference was observed between the groups in any week.

FCR
The weekly cumulative FCRs, for three groups of ducks, are presented in Table-7. There was no significant (p≥0.05) difference between the groups in 3 rd and 4 th weeks. In the 5 th week, each of the Azolla-fed group registered a lower value than the control. In the 6 th week, the 10% Azolla group (G 3 ) showed a significantly(p≤0.01) lower value than group G 1 or G 2 , there being no significant difference (p≥0.05) between the latter two groups. Overall, the 10% Azolla group(G 3 ) showed the best feed efficiency followed by the 5% Azolla group (G 2 ) and the control group(G 1 ), in that order.

Economics of production
The economics of production of broiler ducks, for the three groups, are presented in Table-8. The production costs were calculated on the basis of feed cost only.
Thus, on the basis of profit/bird or profit/kg live weight, each of the Azolla-fed group showed higher economic efficiency than the control. Between the Azolla-fed groups, group G 3 showed a higher efficiency than group G 2 .

Chemical composition of Azolla
The CP content of Azolla, estimated in the present study, was (25.40%) which was almost similar to the results obtained by Balaji et al. [12]. However, Basak et al. [3] reported the higher value of 25.78% CP. The CP contents of Azolla estimated by Cherryl et al. [13] and Parashuramulu et al. [14] were found to be 23.49% and 21.37%, respectively, which were lower than the estimated CP in this study. In the present study, it was found that the crude fiber content obtained was 14.23% which is in line with the value obtained by Parthasarathy et al. [15]. The ether extract content of Azolla in the present study (2.58%) is almost similar to the earlier observations of Parthasarathy et al. [15] and Parashuramulu et al.

Body weight and gain in body weight
Body weights, for each group, increased progressively in successive weeks till the end of the experiment (6 th week). In the 5 th week, group G 3 showed significantly (p≤0.01) higher weights than group G 1 or     G 2 , while there was no significant (p≥0.05) difference between the latter two groups. This implies that feeding of fresh Azolla had beneficial effect on the body weight of ducks without any detrimental effect and a comparable gain in body weight as control group. Provision of free choice diets instead of a complete conventional ration was suggested to have beneficial effects [17]. Choice feeding allows birds a greater opportunity to select the nutrients needed for maintenance and production [18] and will also allow ducks to select correct proportions of the different supplementary feeds to complement their intake. In the course of experiment, it was noticed that ducks had a preference for Azolla over the concentrate for which the birds consumed Azolla part first. Azolla, which is rich in CP and contains high metabolizable energy level, might have improved digestion and also the availability of the dietary nutrients [19]. Furthermore, this might be due to higher bioavailability of essential nutrients present in Azolla as it is rich in protein and contains almost all essential amino acids and several growth promoter intermediaries, minerals like calcium, phosphorous, magnesium, potassium, iron, and copper,and the highest nutritive value of this plant derives from the non-structural metabolically active makeup of the plant [20]. Apart from nutrients, Azolla also contains certain compounds, such as carotenoids, bio-polymers, and probiotics, which contribute to higher productivity and health of animals [14]. Supplementation of Azolla at 10% level exhibited higher growth rate than that in 0 or 5% level. This finding is in agreement with those of Sarria and Preston [21] who reported an increase in growth of broilers when soybean protein was replaced by Azolla up to 15% level, when fed at 0%, 10% or 15% level. Seth et al. [22] also found higher weight gain in Vanaraja chicken fed Azolla at 5% or 10% as compared to those not fed with Azolla. Saikia et al., [23] found that highest body weight gain was in 5% inclusion group and lower in 15% inclusion group and the reason mentioned by them as higher level of crude fiber in Azolla meal and they conclude that Azolla can be included in poultry ration up to 10% level without any significant effect in the performance of broilers for economic effect.
In studies on ducks, the findings in present study corroborate to those of Bacerra et al. [6] who reported an increase in daily gains of ducks at 15% replacement of soybean with Azolla and that Azolla inclusions at 20%, 45%, or 60% level depressed growth rate. Escobin [24] on the other hand, reported that in growing Muscovy ducks, no difference in production efficiency could be noticed by partially replacing traditional rations with Azolla at levels of 0%, 20%, 30%, or 40%. These differences might be due to the difference in the duck types used, their basal ration, and environmental conditions.

Feed consumption and FCR
No significant (p≥0.05) difference was observed between the groups in any week. The lower consumption in Azolla fed groups might be due to feeding of fresh Azolla with higher moisture content which led to gut fill and hence depressed feed intake. It was also noticed in the course of the experiment that ducks had a preference for fresh Azolla to concentrate and consumed the Azolla portion first. The beneficial effects of dietary Azolla on FCR, as observed in the present study, corroborate those reported by several authors. Basak et al. [3] found increased efficiency at 10%, Seth et al [22] at 5-15% level, Chichilichi et al. [25] at 5% levels of Azolla in the diet of chicken. In trials with ducks, Bacerra et al. [6] found that by inclusion of Azolla from 15% to 60% in diet supplying 15.2-30.3% of the total protein, the FCR decreased with increase in consumption of Azolla. Similarly, Lawas et al. [26] observed that by feeding Mallard ducks with normal commercial feed allowance of 150g/head/day or 75g/head/day + ad lib. Azolla, the FCR was lower for the Azolla-fed group. Basak et al. [3] reported that by replacing sesame meal with Azolla at 5-15% level, the protein and energy efficiency, as well as feed efficiency, decreased with addition of Azolla at levels above 5%. Naghshi et al. [4] also recorded reduced feed efficiency at Azolla inclusion above 5% level. The findings in the present experiment are at variance with those of other authors with respect to the maximal levels of Azolla inclusion in diets for improved feed efficiency. Saikia et al., [23] found that Azolla did not affect the feed consumption up to 15% inclusion level, and they concluded that Azolla has no deleterious effect on palatability of the diets.
On the other hand, several authors have reported that inclusion of Azolla at different levels in the diet had no effect on FCR [12,15]. Saikia et al. [23] in their study found that 15% Azolla fed groups having significantly highest FCR, and they stated the responsible factor as a higher level of crude fiber and tannins.
While Basak et al. [3] opined that the higher level of fiber in aquatic plants could be the reason for decreased nutrient utilization and ultimately decreased FCR, Alcantara and Querubin [27], on the other hand, viewed that broilers could readily digest the crude fiber in Azolla, so that the digestibility might not have been a limiting factor. They attributed the reason to a decrease in dietary energy density in the ration as reflected from the higher feed consumption in Azollafed birds. Rai etal. [28] concluded that the smaller leaf size was suitable for intake by chicks as well as adults and Azolla fed ad lib., when substituted 50% of commercial feed, could provide sufficient nutrient. In the present experiment, the feed consumption for the Azolla-fed groups was not increased, nor there any possibilities of decrease in energy density of ration as the rations made isocaloric. Hence, increased feed efficiencies were recorded with increased levels of Azolla in the diet.

Economics of production
Thus, on the basis of profit/bird or profit/kg live weight, each of the Azolla-fed group showed higher economic efficiency than the control. Between the Azolla-fed groups, group G 3 (10%) showed a higher efficiency than group G 2 (5%).Economization of feed cost in poultry by dietary inclusion of Azolla at different levels has been reported by several authors, namely, Basak et al. [3], Seth et al. [22],Chichilichi et al. [25],Naghshi et al. [4]. In ducks also, the inclusion of Azolla in rations has been reported to reduce feed cost significantly [6,24,26,29,30]. Rai etal. [28] found in their study that in situ cultivation and feeding of Azolla to birds under semi-range saved the feed cost by 80%. The higher efficiencies shown by the Azolla-fed groups were due to cheap production cost in terms of utilizing unconventional feed source with suffice nutrient content resulting in proper growth and hence entertains the holistic development.

Conclusion
From the experiment, it was concluded that, inclusion of Azolla at 5% or 10% level in the diet improved body weight, gain in body weight and FCR which was at par with standard basal diet.Feed cost of production was substantially minimized by inclusion of Azolla at either level. Inclusion of Azolla at 10% level showed the maximum economic benefit.

Authors' Contributions
The present study was a part of original research work by PA during his MVSc thesis program. GPM conceptualized the aim of the study, designed, planned and supervised the experiment. Collection of samples, execution of experimental study was done by PA, SKM, and NCB. Analysis of data, interpretation of the results and drafting of manuscript was done by PA and CRP. GGP, CRP, SKM, NCB, BM helped in analysis, draft and revision of the manuscript.All authors read and approved the manuscript.