Received Date: June 28, 2012; Accepted Date: August 18, 2012; Published Date: August 28, 2012
Citation: Hasan BMA, Guha B, Datta S (2012) Optimization of Feeding Efficiency in Semi-Intensive Farming System for Sustainable and Cost Effective Production of Penaeus Monodon Fabricius. J Aquacult Res Dev 3:149. doi:10.4172/2155-9546.1000149
Copyright: © 2012 Hasan BMA, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Four different feeding frequencies, i.e., 3 times (T1), 4 times (T2), 5 times (T3), and 6 times (T4) were used with supplementary feed (38% crude protein) in the experimental ponds to determine the optimum feeding frequency for sustainable and cost efficient production of Penaeus monodon. Post larvae of black tiger
(initial weight 0.02 ± 0.0013 g) with stocking density of 20 m2 was cultured for 110 days to evaluate the sustainable production by taking different parameters of feed utilization efficiency (FCR, PER, FER, production yield); and adequate growth level (WG, SGR, survival) of cultured shrimp. During production cycle, various water quality parameters of the ponds were found within normal
range (Matias et al. 2002) except for NH4-N, NO3-N and PO4-P which were significantly lower in T3 (p<0.05, 0.01) and for PO4-P in T4 (p<0.05) series than T1. Final weight gain (WG) and specific growth rate (SGR) was significantly higher in T2, T3, and T4 pond than T1 (p<0.05, 0.001). The feed efficiency ratio (FER), protein efficiency ratio (PER) and feed conversion ratio (FCR) followed the same pattern as WG and SGR (p<0.05, 0.01, 0.001) in T2, T3, and T4 series than T1. Finally, significantly higher (p<0.05) survival and more net profit of cultured shrimp in T3 ponds than other ponds (T1, T2, and T4) have an additional support towards sustainable shrimp culture practices. In fine, on the basis of final yield and net profit of treated ponds it was found that 5 times feeding frequency (T3) proved most effective in augmenting sustainable and cost efficient production of P. monodon in a semi intensive system of
Feeding frequency; Growth; Cost efficient; Penaeus monodon
In recent years, feed management is a key factor affecting water quality and production economics in aquaculture [1-3]. Failures in shrimp production are mainly due to PL quality, feed, water and soil quality or disease but in most cases origin of problem is poor feed management . However, environmental, social and economic considerations drive the need to improve feed management and feed formulations . Feed is the initial source of pollutants as overfeeding or poor quality feeds can severely effects water quality and production of shrimp . Thus, daily inputs of supplementary feed must be reasonable and should consider growth of the shrimp as well as nutrient capacity of the pond ecosystem. Supplementary feed in shrimp farming is not only the initial source of physiological wastes, but it accounts for 55-60% of the operation costs in intensive and 40-50% in semiintensive culture system [6,7]. It was reported that increased feeding rate beyond the natural carrying capacity of the pond deteriorates the water quality . Out of total feed applied to pond, only 16.7% (by dry weight) is converted into shrimp biomass, the rest is leached or otherwise not consumed, egested as faeces, eliminated as metabolites, etc.. Negative effects of supplementary feed are not isolated but promote diseases and other water quality related problems which affect production [1,10]. Therefore, feed management strategy should be aimed at optimizing feed inputs, reducing feed conversion ratios and the potential impact on the culture and effluent water . Protein is the central to feed formulation system and the most important constituent in prawn nutrition . Minimum dietary protein requirement for Penaeus monodon was reported to 35-50% . On the other hand, multiple daily feeding and distribution is desirable as shrimp eat slowly and almost continuously . However, increased feeding frequency was reported to reduce nutrient leaching and improves feed utilization efficiency . Both feed quality and management may have an important role in governing production and feed conversion efficiency as well as minimizing pond bottom and water quality deterioration due to over feeding .
Impact of feeding frequency inside ponds is not well understood and no clear information is available as many farmers usually vary in practice to apply feed 2-6 times daily. However, some information on feeding frequency of 2-4 times per day is applicable in shrimp ponds . Scientific information regarding feed management in shrimp farming from both economic and environmental perspectives is meager. Furthermore, much needed field measurements of performance of commercial feeds are rather scanty in India. In the present study, four different feeding frequencies, i.e., 3 times (T1), 4 times (T2), 5 times (T3), and 6 times (T4) were used with supplementary feed (38% crude protein) in the experimental ponds to determine the optimum feeding frequency for sustainable and cost efficient production of P. monodon. Sustainable production of cultured shrimp was determined by estimating feed utilization efficiency (FCR, PER, FER, production yield) and growth level (WG, SGR and survival) of cultured shrimp. Thus the aim of present study was to determine the optimum feeding frequency for sustainable and cost effective production of P. monodon in the brackish water ponds of West Bengal, India.
Black tiger shrimp, P. monodon Fabricius (1798) was cultured for 110 days between August and December, 2010 in twelve earthen ponds (~0.5 ha each) randomly selected in Kar shrimp farm (Mahishadal, East Medinipur, West Bengal, India; Lat 21°55’ N, Long 88°46’ E).
Three ponds each were used to culture the shrimp for different feeding frequencies: (i) 3 times (T1), (ii) 4 times (T2), (iii) 5 times (T3), and (iv) 6 times (T4). All the experimental ponds were rectangular in shape with facility of both inlet and outlet structures with average 1.2 meter water depth. Soil was clayey loam and aeration was maintained for all ponds during culture.
Rearing in ponds
Similar pond management practices like drying, tilling, liming, water exchange and feeding of shrimp was done as per the method in all the experimental ponds during culture. Initial filling of ponds was done by saline water directly pumped from Haldi river creek after filtered by fine mesh bag net . After two days of chlorination, both organic (poultry litter, available locally) and inorganic (urea containing 46% N and single super phosphate containing 16% P2O5) fertilizers were applied to improve natural productivity of pond. Good quality and disease-free post larvae (pl-20) of P. monodon were procured from a private hatchery (Vaisakhi Hatchery, A.P.), then acclimatized and stocked @ 20 post larvae m-2 in all the ponds.
During culture, shrimps were fed with standard commercial palletized feeds (crude protein-38%, fat-5%, fiber-4%, ash-12-15%, calcium-2.2-2.5% and phosphorus-1.5-1.8%) and applied following the feed chart given by feed company (Chorean Pokhpand-Novo, Chennai, India). The feeding regime of cultured shrimp has been presented in Table 1. Feeding was administered according to their body weight and days of culture in a fix quantity in all treatments. Feed was broadcasted by rope method using floats in all ponds.
|Feeding frequency (Times day-1)||Time of feeding ( daily )||Amount of feed ration ( % daily )|
|Three||7:00, 15:00, 20:00||35, 30, 35|
|Four||7:00, 11:00, 15:00, 20:00||30, 20, 30, 20|
|Five||6:00, 10:00, 14:00, 18:00, 22:00||20, 20, 20, 20, 20|
|Six||5:00, 8:00, 11:00, 15:00, 18:00, 22:00||20, 15, 15, 15, 20, 15|
Table 1: Feeding regime in the experimental ponds.
The feeding was conducted twice from days of culture (DOC) 1-14, three times from DOC 15-44 and 3-6 times from DOC 45 onwards till harvest. From 45 DOC onwards till harvest 3-6 times feeding was followed as per experimental design (Table 1). From DOC 1-44 feed (crumble type) was applied for small shrimps and from DOC 45 onwards feed (pellet type) was used for bigger shrimps. A portion of feed placed on check tray to estimate appetite or consumption by refused portion after a period of time . Aeration was kept off for two hours during feeding time.
Evaluation of feed efficiency and growth
Shrimps were sampled every fortnight by cast net for monitoring the growth, survival and health conditions of shrimp and for estimation of total biomass in the experimental pond. Shrimps weight gain (WG), feed conversion ratio (FCR), survival rate and specific growth rate (SGR) was measured as per conventional method in every fifteen days . Protein efficiency ratio (PER) and feed efficiency ratio (FER) was estimated by routine methods [19,20]. The average body weight (ABW) and survival rate was calculated following the method . The formulae to calculate different parameters are as follows:
Weight gain (WG) = Final weight (g) - initial weight (g)
Food conversion ratio (FCR) = Total feed consumed (kg) / total yield (kg)
Specific growth rate (SGR) = 100×(Wf-Wi)/period (days) [Wf is final weight and Wi is initial weight]
Protein efficiency ratio (PER) = Wet weight gain (g) / Protein fed (g)
Survival rate = (N/N )×100 [N and N are initial and final number of shrimps, respectively]
Feed efficiency ratio (FER) = Final weight (g)-initial weight (g)/ total feed intake (g)
Different water quality parameters like temperature, dissolved oxygen, pH were monitored twice a day (6-00 and 16-00 hrs); salinity and transparency once a week (11-00 hours) in situ at farm site by multiparameter device YSI, MP556 mode and secchi disc. Other nutrient parameters (NH4-N, NO3-N, PO4-P), total alkalinity were monitored in monthly intervals during the production cycle [1,21].
Data obtained from the results were subjected to statistical analysis. One-way analysis of variance (ANOVA) was done with the help of MS Excel and computer software SPSS (version 7.5) and the sample means compared . Significance was calculated by students’-t test between T1 (lowest feeding frequency) with other series.
Water quality parameters
Different physical and chemical parameters of water varied widely in different treatment ponds (Table 2). It was found that among the water parameters temperature, salinity, transparency, pH, dissolved oxygen and alkalinity of water showed no significant differences between the treatment ponds during the culture period. However, the concentration of nutrients (ammonium-N, nitrate-N, and orthophosphate) varied with the feeding frequency in the cultured ponds. The level of nitrate-N and ammonium-N in T3 pond was found significantly reduced than T1 ponds (p<0.05, 0.01). On the other hand, the amount of orthophosphate reduced significantly (p<0.05, 0.01) in both the T3 and T4 ponds than T1 pond during the culture period.
|Variable||Treatment 1||Treatment 2||Treatment 3||Treatment 4|
|Temperature (°C)||25.92 ± 2.32||25.86 ± 2.67||25.91 ± 2.33||25.93 ± 2.33|
|Salinity (g l-1)||12.5 ± 2.78||11.71 ± 2.4||12.33 ± 2.52||12.49 ± 2.53|
|Transparency (cm)||53.75 ± 7.75||51.2 ± 8.04||45.1 ± 4.78||43.02 ± 8.92|
|pH||7.94 ± 0.10||7.95 ± 0.10||7.93 ± 0.10||7.96 ± 0.11|
|Dissolved Oxygen (mg l-1)||3.58 ± 0.56||3.55 ± 0.64||3.70 ± 0.63||3.69 ± 0.63|
|Nitrate-N (mg l-1)||0.73 ± 0.2||0.45 ± 0.07||0.44 ± 0.06a||0.58 ± 0.09|
|Ammonium-N (mg l-1)||0.18 ± 0.03||0.14 ± 0.02||0.08 ± 0.01b||0.12 ± 0.06|
|Ortho-phosphate (mg l-1)||0.11 ± 0.02||0.07 ± 0.01||0.04 ± 0.01b||0.06 ± 0.01a|
|Total Alkalinity (mg l-1)||113.0 ± 20.7||114.2 ± 16.3||122.2 ± 20.3||115.0 ± 17.4|
a, b, c in the same row with different superscripts are significantly different. p values: a<0.05; b<0.01; c<0.001. Values in each row with no superscript are non-significant. Sources:
*Fast and Lester, 1992 ; **Abesamis, 1989 ; ***Tsai, 1989 ; NA= not available
Table 2: Water quality characteristics in feed trial ponds (Mean ± SE of 3 ponds each).
Growth and feed utilization efficiency
Final weight, WG, SGR and survival was used to evaluate the growth performance of cultured shrimp with the frequency of feed applied in different cultured ponds. While comparing the data of T1 pond with that of other ponds it was found that final growth, WG and SGR have similar pattern of increase and become significant (p<0.05, 0.001) (Table 3). However, the survival of cultured shrimp was higher in all the cultured ponds than T1 but it was significant for T3 pond (p<0.05) (Table 3). FCR, PER, FER, daily biomass increment and yield of cultured shrimp in different ponds was presented in Table 4. The FCR was found to be reduced as the feeding frequency in cultured ponds increased but it was significant for T2 and T3 (p< 0.01). On the contrary, a reverse result was obtained in case of PER and FER which was found significant in T2 and T3 pond when compared with T1 (p<0.05, 0.01, 0.001) (Table 4). In case of daily biomass increment, significantly (p<0.01, 0.001) higher result was obtained in T2 and T3 ponds than T1. After 110 days of culture highest yield (4561.51 kg ha- 1) was obtained in T3 ponds followed by T2 ponds (4058.22 kg ha-1). In other two ponds (T1 and T4) the production was relatively lower than T2 and T3 (Table 4). Production cost was found to be higher as the feeding frequency increases (Rs. 1,500 for every higher frequency) but the difference in production cost is due to more labor cost in higher feeding frequency ponds. Although total cost was slightly higher in T3 pond than the others but lowest cost/benefit ratio (1.54) in this pond as compared to others amply speak for effective profit after culture (Table 4).
|Variable||T1 (3 times)||T2 (4 times)||T3 (5 times)||T4 (6 times)|
|Final weight (g)||22.9 ± 0.20||26.3 ± 0.27c||27.67 ± 0.26c||24.17 ± 0.23a|
|WG (g)||22.88 ± 0.20||26.28 ± 0.26c||27.64 ± 0.26c||24.14 ± 0.23a|
|SGR (%day-1)||20.80 ± 0.31||23.89 ± 0.24c||25.13 ± 0.23c||21.95 ± 0.21a|
|Survival (%)||70.5 ± 4.1||77.17 ± 2.91||82.47 ± 2.91a||73.03 ± 4.52|
a, b, c in the same row with different superscripts are significantly different. P values: a<0.05; b<0.01; c<0.001.
Table 3: Variations of different growth parameters in treatment ponds.
|Variable||T1(3 times)||T2(4 times)||T3(5 times)||T4(6 times)|
|FCR||1.86 ± 0.11||1.48 ± 0.03b||1.31 ± 0.02b||1.7 ± 0.04|
|PER||1.42 ± 0.05||1.75 ± 0.06a||2.0 ± 0.02c||1.55 ± 0.04|
|FER||0.54 ± 0.02||0.67 ± 0.01b||0.76 ± 0.01c||0.59 ± 0.02|
|Increase in biomass (kg d-1ha-1)||29.35 ± 1.0||36.89 ± 0.73b||41.47 ± 0.45c||32.07 ± 0.87|
|Yield (kg ha-1)||3228.9 ± 112.9||4058.22 ± 80.5b||4561.51 ± 55.2c||3527.72 ± 95.5|
|Total cost (Rs. ha-1)||7, 26,100||7, 27,600||7, 29.100||7, 30,600|
|*Net Profit (Rs. ha-1)||65,005||2, 86,912||4, 72,670||1, 23,000|
|Cost benefit ratio||11.17||2.54||1.54||5.94|
a, b, c in the same row with different superscripts are significantly different. P values: a<0.05; b<0.01; c<0.001. *1 US$ = 49 (Indian rupees, Rs.)
Table 4: Variations of different feed efficiency parameters with cost benefit analysis.
In the present study it was found that feeding frequency has a profound influence on cost effective and sustainable production of P. monodon. Different growth and feed efficiency parameters have found to be modulated by changed feeding frequency although feed constituents, feed amount and distribution were similar in all the culture ponds. Initial SGR of P. monodon was almost same (9.71-11.57%) in all the ponds which increased steadily between DOC 60-75 in all ponds. After DOC 75, it reduced and collapsed after 90 days (11.33%) till harvest (Figure 1a). This may be due to the fact that larval shrimp generally depend on planktonic food at the early stage, after which they gradually acclimatize to the supplementary feed . SGR increased steadily between 60-75 DOC in all ponds but the maximum value of SGR (38.44%) in T3 ponds was observed in DOC 60 with gradual declining trend thereafter (Figure 1a) corroborated the previous finding . It was also found that average body weight (ABW) of P. monodon increased as culture time progressed in all ponds.
At harvest, the highest ABW was observed in T3 (27.67 ± 0.26 g) followed by T2 (26.3 ± 0.27 g), T4 (24.17 ± 0.23 g), and T1 (22.9 ± 0.20 g) (Figure 1b). Previous study found almost similar growth (29.24 ± 1.44 g) pattern for 40% protein feed in 120 days of culture . Therefore, it can be substantiated that decline in temperature below 25°C could decrease feed consumption and growth rate, thus lower temperature at the end of culture (22.1°C) in ponds caused poor consumption of feed and responsible for slow growth rate of shrimp . However, ideal water stability ensures better feed consumption and good pond bottom and water quality . As shrimp live on or near to bottom of pond, higher concentration of NH4-N and NO3-N found in T1 and T4 ponds affected the health, feed intake and growth; and possibly lower survival . However, lower level of orthophosphate in T3 ponds was found to be suitable for good growth of shrimp. This was happened due to less feed wastes which can be substantiated by lower FCR value in these ponds (Table 4) . Furthermore, feed pellets are known to disintegrate faster in water facilitate only economic loss and pollution of water . Thus, frequent occurrence of black soil formation in T1 and T4 ponds causing black gills due to accumulation of feed wastes resulting higher FCR that showed clear temporal variation during the culture period and this increased as time progresses (Figure 1c). FCR value was lowest (1.31 ± 0.02) in T3 pond followed by T2 (1.48 ± 0.03), T4 (1.7 ± 0.04) and highest in T1 (1.86 ± 0.11). Feed is one of the essential inputs in shrimp production and decides for profitability. The cost of labor for feeding of shrimp ponds can be a significant component of the fixed costs  as found in this study (Table 3). However, moderate feed inputs of 2-4 times day-1 (depending on shrimp size) are often recommended for better growth . From the present result it is clear that moderate feeding of five times in T3 pond fetched best net profit and C/B ratio (Table 4). Feed conversion improves with increasing feeding frequency, but the interesting feature of the study is that FCR improves up to 5 times feeding frequency (T3) but not for further increment of frequency (T4) (Figure 1c and Table 3) . It is found that survival rate is highest (mean 82.47%) in T3 ponds, followed by T2 (77.17%), T4 (73.03%), and T1 (70.5%) ponds (Figure 1d and Table 3). An average survival of 70 to 80% is quite possible if the ideal condition is maintained for P. monodon . It is found that five times feeding reduced cannibalism (during molting and natural mortality) because gut evacuation is completed in about 3 hours for penaeid shrimps as a way to reduce or eliminate excess uneaten feed waste, which might have happened in T4. And in T1 and T2, less feeding frequency might induce cannibalistic behavior of shrimps as feed availability was not enough throughout the day .
Protein being the most important and expensive nutrient in shrimp feed, and nutritionally well-balanced diet is important for profit . The best value observed for protein efficiency ratio (PER) in this study was 2.0 in T3 pond followed by T2 (1.75), T4 (1.55), and T1 (1.42) (Table 3). Previously, PER value of 2.55 was reported in ponds feeding with same protein content, i.e., 38% . Thus, 5 times feeding is the best to utilize the protein conversion to shrimp as found in this study. In this study highest Feed efficiency ratio (FER) value obtained in T3 ponds (0.76) and lowest (0.54) in T1 ponds indicating maximum utilization of feed resulted in ponds of T3 for 5 times feeding; and it is much better and improved than earlier findings (0.57-0.69), and (0.47) [20,33]. This good outcome might be due to better feeding management, feeding frequency in particular, with efficient bottom water exchange to flush the wastes. In the present study, black tiger shrimp achieved highest growth (WG and SGR) from same diet with 5 times feeding frequency (Table 3). However, the less frequent feeding in T1 (3 times) and more frequent feeding in T4 (6 times) significantly limited WG, SGR, FCR, PER and FER in comparison to T3 and T2 ponds (Tables 3 and 4). In both the cases, feed quantity might have wasted more as reflected in pond sediments (black soil) and deteriorated water quality in T1 and T4 ponds. The present study in a brief has developed maximized production efficiency, reducing feed wastage and no deterioration of water quality in T3 ponds. Lesser or higher than 5-times feeding frequency indicated poor growth, wasted energy on part of shrimp and economic loss.
Thus, in a semi intensive culture system, 5-time feeding frequency was the most efficient and cost effective feeding management technique that resulted in highest yield and profitability, and lowest nutrient loads in the effluents which may convince it as sustainable and eco-friendly method of farming practice.
The authors are grateful to Mr. Biswadev Kar, proprietor of the farm (M/S. Kar Shrimp Farm) for providing the ponds with all logistics and inputs in time for the study. They are thankful to the technicians for data recording and supporting during sample collection and analysis.