Practical Methods Of Improving Health & Performance In Pangasius Culture In Vietnam

September | October 2009 Feature title: Practical methods of improving health & performance in Pangasius culture in Vietnam International Aquafeed is published five times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2009 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058

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Pangasius

Pangasius Table 1: Commercial diet composition

Ingredient Fishmeal 60% protein

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Practical methods of improving health &

performance in Pangasius culture in Vietnam by Le Thanh Hung, Nguyen Thi Thanh Truc and Vo Thi Thanh Binh of the Faculty of Fisheries, Nong Lam University, Ho Chi Minh City, Vietnam and Thien Le of Alltech Vietnam Co Ltd, Ho Chi Minh City, Vietnam.

A

quaculture production in Vietnam has been developing since the early 1960s. In the last 20 years rapid expansion has taken place due to the development and diversification of intensive production methods especially for the production of species for export markets.

tilapia, catfish and freshwater and brackish water shrimps. Today brackish water shrimp and catfish dominate aquaculture production for export.

Catfish production

Image 1: Location of the Mekong Delta

Vietnam has 3260km of coastline and 1.7 million ha of inland area available for

aquaculture and cultures a great variety of aquaculture species including: carps,

Catfish have been farmed in the Mekong Delta region of Vietnam (Image 1) for 50 years and although 12 species of catfish are known to exist, only two species Pangasius hypophthalmus (Tra) and Pangasius bocourti (Basa) are

Table 2: Feeding treatments

(% dry diet)

% dry matter

5.00

Cassava

27.45

Fish Oil

0.15

Rice bran

37.28

Soy oil

0.15

Meat-bone meal

13.72

Premix

1.00

D,L-methionine

0.25

Image 2: commercial growing ponds & floating cages 10 | InternatIonal AquAFeed | September-october 09

In addition to the difficult economic environment the catfish industry is also facing many production challenges. The rapid development of the industry and reduction in profits has necessitated the development of more efficient management practises. Production planning, husbandry techniques, feed, health and water resources

No Bio-Mos

No Bio-Mos

Treatment 1

Bio-Mos (2kg/ton)

Bio-Mos (1kg/ton)

Treatment 2

Bio-Mos (4kg/ton)

Bio-Mos (2kg/ton)

Control

Bio-Mos

Production challenges

Second phase (week 5-10)

15.00

Soybean meal

grown commercially using a variety of culture methods from ponds to floating cages. (Image 2) The Vietnam Association of Seafood Exporters and Producers (VASEP) report that Pangasius farming doubled from 400,000 tonnes in 2005 to 825,000 in 2006 and reached 1.1 million tonnes in 2008. The processed products from Basa and Tra catfish exported in 2008 had a value of US$1.4 billion with exports going to over 100 countries. In 2008 most exports went to the European Union 35%, Russia 18%, Ukraine 12% and smaller amounts to Asean, China, USA, Mexico, Egypt and others. Production forecasts from the FAO in the 2009 Pangasius Market Report anticipated that Vietnam would produce 1.5million tonnes of catfish this year. However, this predicted growth may not be achievable due to the challenges faced by the industry today. Growing production costs due to high feed prices, lack of processing infrastructure and storage combined with market uncertainty, due to difficulties resulting from some importing countries setting up technical barriers to limit imports, have resulted in many farmers in the Mekong Delta stopping or suspending the culture of catfish. VASEP report that this may be as high as 30 percent of catfish breeders and will result in an overall drop in catfish production when compared to 2008.

First phase (week 1-5)

treatment

produce more robust and healthy juveniles have to be optimally managed in order for stock recruitment. This results in long to achieve cost effective production and tem improvements in product quality and ensure market competitiveness. safety therefore ensuring sustainability and The occurrence of fish diseases has contributing to rural development. severe economic implications for the farmer due to stock loss, sub-optimal growth performance and the requirement Bio-Mos and Tra catfish for therapeutic intervention. In the Faculty of Fisheries at the With low survivals, high feed costs and University of Nong Lam our research group low profit margins farmers are looking for has been investigating the effect of Bio-Mos, ways to improve growth and performance a mannan oligosaccharide from Alltech Inc, and reduce mortality in their catfish stocks. USA, on Tra catfish. The improvement of these performance parameters is their most effective tool to impact their overall cost of production. Prophylactic strategies aimed at the reduction of stress and exposure of fish to potential pathogens includes strict operational management and bio-security programs. Vaccination is not available for catfish in Vietnam and focus has The premier meeting point for the feed and food industry in 2010. Addressing common concerns and identifying opportunities. shifted to nutritional strategies Join us in Cancun, Mexico!. For more information visit: that impact on fish performance parameHosted jointly by in co-operation FAO & IFIF with Conafab ters and aim to

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Pangasius

Pangasius tion were acclimatised in the University’s experimental farm for three weeks prior to transferring 300 fish of 12-13g average weight to each of 12 hapas (1x1x1m). (Figure 3) These fish were fed experimental diets with and without Bio-Mos for five weeks when 150 fish were removed for the assessment of fish health, challenge test and stress status. The remaining fish continued to be fed the assigned treatment for a further five weeks. The diet fed to the fish was juveniles from a common population were acclimatised in the University’s experimental farm for three weeks prior to transferring 300 fish We have demonstrated that Bio-Mos supplementation can play an important role in improving health status, help optimise performance through improved growth and

FCR, improve stress and disease resistance and positively influence gut morphology. In a series of experiments, Tra catfish juveniles from a common popula-

a floating extruded feed based on a commercial formulation produced in a local feed mill (see Table 1). The treatments applied, with four replicates per treatment, are shown in Table 2. All the fish in the different treatment groups were fed twice daily to satiation.

Growth and performance

Figure 2: Trail facilities and challenge methods used

Injection with bacteria

Cohabitation with parasite Cohabitation with bacteria disease

12 | InternatIonal AquAFeed | September-october 09

After five weeks the fish fed Bio-Mos showed improved fish performance in comparison to the control treatment and this improvement continued to be measured in the second phase of the feeding experiment. The specific growth rate in the first feeding phase was significantly increased from 1.94 to 2.48 percent/day and in the second phase from 1.88 to 2.13 percent/day. Survivals were also statistically improved in the Bio-Mos supplemented groups. Feed intake in the trial had a tendency to decrease in the fish fed Bio-Mos. The food conversion rate (FCR) was significantly reduced from 1.64 in

Figure 1: Intestine section of fish fed Bio-Mos supplemented feed for 5 weeks (x40). the control treatment to 1.09 with the 0.4 percent Bio-Mos supplementation in phase 1 and from 1.39 in the control treatment to 1.14 with the 0.2 percent Bio-Mos supplementation in phase 2. It should be noted that the FCR’s calculated in this experiment are higher than those expected for catfish in pond culture, typically varying from 1.0 – 1.1, due to the high densities of 300 fish/m3 and concrete tanks used in the experimental facilities. The results would appear to indicate that the Pangasius had better digestion and nutrient utilisation with the Bio-Mos supplemented feeds.

may help explain the higher efficiency of feed use with better FCR’s in the Bio-Mos supplemented feed.

Stress tests

high (63.75 – 81.25%). Lower survival was observed in the control fish but the differences were not significant. In contrast challenging fish with high ammonia levels (150mg/l) indicated that 0.2 percent Bio-Mos supplementation

After the first phase of the experiment was completed fish from the different treatments were subjected to a salinity (15‰) stress test and after the A new generation of omega-3 lipids second phase with a broader spectrum of health an ammonia benefits. (150mg/l) stress test. (see Table - High DHA contents, preferably in 3). The fish easily digestible and highly bio challenged to available form for aquaculture use. 15‰ salinity - Numerous benefits on improving adapted well as the survival the immune response, better rates after weight gain and physical five challenged conditions of land animals. days are quite

Marine phospholipids

Gut morphology The gut morphology of these fish was examined to investigate whether any differences in the dietary treatments could be observed. Under light microscopy examination of the intestinal section showed that the fish fed 0.2 and 0.4 percent Bio-Mos had a higher density of villi than the control diet (see Figure 1). . The more complex and dense structure of the gut

Table 3: Survival rates of fish when transferred to saline water or water with high ammonia concentration

Salinity test (15‰)

treatment Phase 2

Ammonia test (150mg/l)

Control

63.75a

Control

28.75 a

0.2% Bio-Mos

76.25a

0.1% Bio-Mos

33.75 ab

0.4% Bio-Mos

81.25a

0.2% Bio-Mos

80.00 b

treatment Phase 1

Different letters in the same column denote significant differences (P<0.05)

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September-october 09 | InternatIonal AquAFeed | 13 999_AD_IAF0904V3.indd 1

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Pangasius helped Tra catfish tolerate a high ammonia concentration allowing an 80 percent survival rate compared to 28.75 percent in the control treatment.

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Tra catfish health status was investigated by cohabitation and inoculative bacterial It appears that the Bio-Mos fed fish challenges with Edwardsiella ictaluri known to cause enteric septicaemia in catfish (ESC). In addition, a challenge test with an external parasite Ichthyophthirius multifilis was undertaken. This parasite is responsible for large fish losses in the industry (see Figure 2). In the inoculative challenge 20 fish from each treatment tank were removed to another tank and injected with 106cells/ ml of Edwardsiella ictaluri and in the cohabitation challenge 30 fish from each treatment tank were removed to another tank have a higher tolerance to ammonia and cohabitation took place with five and this may possibly be due to the infected fish. This took place at the end increased skin mucous observed which of the first and at the end of the second acts as a protective barrier. feeding phase. In the cohabitation challenge with the external parasite Ichthyophthirius multifilis 30 fish from each treatment tank were removed to another tank and cohabited with five infected fish. The incidence rate and severity of infections was determined by counting the number of Ichthyophthyrius multifiliis on each gill arch and skin under the microscope at 40x magnification. The survival rates from the different challenge methods are shown in Figure 3. Bio-Mos supplementation at 0.4 percent, in Phase Figure 3: Survival rates of fish fed Bio-Mos and then 1, has significantly challenged with bacterial injection, cohabitation with improved survival bacterial infected fish or with parasites for the first and second feeding phases. compared with the

Phase 2 2

Phase 1

The inclusion of 0.2 percent Bio-Mos can also protect Tra catfish from external parasites and bacterial disease challenges, improve performance and increase their tolerance to high ammonia levels.

14 | InternatIonal AquAFeed | September-october 09

control treatment in the cohabitation and parasite challenges, but not for the bacteria injection challenge. In Phases 1 and 2, Bio-Mos supplementation at 0.2 percent increased the survival rates in bacteria and parasite challenges. However, these were not significantly different from the control except for the survival rates in the bacteria injection challenge of Phase 2.

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Parasite challenge In the parasite challenge the results showed that Bio-Mos supplementation had the ability to protect Tra catfish from external parasites. The incidence and severity rates of Ichthyophthirius on the skin and gill was significantly reduced in the 0.2 and 0.4 percent Bio-Mos treatments (see Table 4).

Cost benefits In order to assess the economic benefit of Bio-Mos supplementation the cost of production was assessed using the improved performance parameters of FCR and survival rates from the work described. This can be seen in table 5 and 6 and is expressed as the cost of production of 1kg of fish produced.

Conclusion Our results have shown that the supplementation with 0.2 and 0.4 percent BioMos in feed can result in better growth performance, feed utilisation and improved survival rates in Tra catfish. In the second Phase 0.2 percent Bio-Mos inclusion resulted in an increased feed cost of two percent but returned a benefit of 16 percent in terms of reduced production cost per kg of weight gain achieved. The inclusion of 0.2 percent Bio-Mos can also protect Tra catfish from external parasites and bacterial disease challenges, improve performance and increase their tolerance to high ammonia levels.

mo re

in fo rmatio n :

Dr Hung Email: [email protected] Ms Thien Le Email: [email protected]

The solution behind the solution.

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Practical methods improving health & performance in Pangasius culture in Vietnam Automated microdiet feeding - another step to early weaning

Hybrid drive - technology for drying aquafeeds

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