Potassium diformate for catfish

Introduction

In the past decade, the export of white Pangasius fillets to EU countries was on high demand and hence, striped catfish production through intensive pond culture increased by eight fold from 0.15 to 1.2 mill tons per year in Vietnams Mekong Delta (Bosma et al. 2009). In 2009, 608,000 tons of Vietnamese striped catfish had been exported mainly to the EU (37%) with Germany and Spain as the top two importers, while Asian countries and the USA imported 7% each, followed by Russia and Ukraine (6%, respectively), Mexico (5%) and Egypt (4%, Josupeit 2010).

Often, Pangasius production in ponds leads to farming setbacks and increased use of antibiotic growth promoters (AGP). However, growing awareness from consumers and producers of aquaculture species has resulted in a demand for responsible and sustainable aquaculture. Since acidifiers such as diformates are one of various alternatives spearheading environmental friendly and nutritive-sustainable aquaculture approaches, positive effects to the growth and health performance had been obtained for salmonids (Lückstädt 2009), tilapia (Lückstädt & Kühlmann 2011) or white leg shrimp (Kühlmann et al. 2011). In the following study, the effects of potassium diformate (KDF) fed to striped catfish on a commercial pond farm trial will be discussed.

Methodology

In an eight-month commercial farm trial, two ponds were stocked with striped catfish with an initial weight of on average 20.4 g (50 fingerlings/m²) and fed twice a day with a commercial diet containing 28% protein. Fish in the treatment pond received a 0.2% KDF (Aquaform^®) containing diet compared to those in the control pond. Both ponds were widely separated to avoid intrusion. Individual fish samplings were conducted twice a month to monitor body mass development. Additionally, daily feed quantities and fish mortalities were recorded. Harvested fish were commercially sold.

Results and discussion

Initial results show that Pangasius received diets with 0.2% KDF-inclusion over the whole trial period averaged in a 22% higher body mass (1050 g vs. 864 g; Figure 1), 23% higher weight gain, an FCR improved by almost 8% and a mortality reduced by 25% compared to control fish. Fish Productivity Index (FPI) of KDF-fed catfish was likewise 41% higher compared to control fish (Table 1).

As a catfish pond in general is a "dirty area" with no visibility below surface caused by complex environmental influences, data on a monthly basis show fluctuating performances between KDF-fed and control fish. After stocking, a disease outbreak (bacillary necrosis) affected KDF-inclusion receiving fingerlings, which initially caused mortalities of 10.9% vs. only 1.7% for control fingerlings. FCR during the second month was very low for both groups due to probably substantial natural food intake. Further, control and KDF-fed fingerlings gained 35.9g vs. 54.1g, resulting in a 51% higher weight gain for the KDF-fed Pangasius. This trend of higher weight gain, similar or lower mortality and FCR with concomitant higher FPI was likewise observed throughout the culture period for KDF-fed vs. control fish except for the sixth month, where control fish showed a higher weight gain and lower FCR compared to KDF-fed Pangasius.

Reasons for the fluctuation scenario could be attributed to complex environmental influences partially stressing the catfish during the grow-out period, especially the shifting weather season (monsoon). Nonetheless, a low concentration of as low as 0.2% KDF (Aquaform^®) inclusion into commercial pellets showed strong effects on the overall performance in terms of growth and FCR, survival rate and Fish Productivity Index. This is due to the double-salt technology in producing a formic acid-formate-double molecule, which carries its active ingredients with efficiencies above 90% into the catfish intestine and counteracts gram-negative pathogenic bacteria in a slow-release mechanism, thereby improving protein digestibility and nutrient uptake for the catfish. KDF-inclusions into commercial feeds as alternative to antibiotics therefore support the approach for EU-export-oriented catfish farms (Figure 2) and poste a strong argument for new ways in fish nutrition.

References

Bosma, R.H., Chau, T.T.H, Potting, J. 2009. Environmental Impact Assessment on the pangasius sector in the Mekong Delta. Wageningen University, 56pp

Josupeit, H. 2010. Pangasius Market Report - March 2010. FAO Globefish, www.globefish.org

Kühlmann, K.-J., Jintasataporn, O, Lückstädt, C. 2011. Dietary potassium diformate improves performance of while shrimp production under controlled conditions. Aquaculture Asia Pacific, 7(2):22-24.

Lückstädt, C. 2009. The use of dietary acidifiers in salmonid nutrition. International Auqafeed Magazine, 12(2):9-11.

Lückstädt, C., Kühlmann, K-J. 2011. The use of diformates in tilapia - ways to improve performance sustainabiltiy. Infofish International (2):22-25.

Table 1: Growth parameters of striped catfish (Pangasius hypophthalmus) during an eight month commercial farm trial fed with or without KDF^† (Mekong Delta, Vietnam)^*

Month	Weight gain (g)	Mortality (%)	FCR	FPI**
	Control	KDF	Δ (%)	Control	KDF	Δ (%)	Control	KDF	Δ (%)	Control	KDF	Δ (%)
1	15.4	19.8	28.3	1.7	10.9	534.8	1.1	0.4	-66.7	143.8	501.8	248.9
2	35.9	54.1	50.8	15.5	1.1	-92.1	0.5	0.9	65.1	582.2	622.7	6.9
3	81.5	116.7	43.3	0.8	0.8	-2.1	1.2	0.9	-21.7	694.2	1270.7	83.0
4	173.0	194.4	12.4	0.3	0.5	62.2	1.1	1.1	5.4	1583.8	1685.3	6.4
5	91.3	164.0	79.7	0.5	0.3	-28.8	2.1	1.4	-34.0	435.1	1186.7	172.8
6	213.1	148.7	-30.2	1.0	0.8	-22.2	0.8	1.2	50.8	2617.5	1214.0	-53.6
7	117.3	147.9	26.1	0.3	0.5	36.6	2.1	2.0	-4.7	544.9	720.1	32.2
8	114.0	186.3	63.4	0.3	0.4	14.6	1.2	1.4	16.5	951.9	1334.2	40.2
Final	826.0	1012.0	22.5	20.5	15.3	25.4	1.3	1.2	-7.7	5051	7143	41.4

^†KDF: potassium diformate – tradename Aquaform^® produced by ADDCON GmbH

^*Initial Body mass: Control = 22.6 g, KDF = 18.2 g

^**FPI = Fish Productivity Index = Weight gain (g) x Survival (%) / (10 x FCR)

Figure 1: Body Mass Development of striped catfish (Pangasius hypophthalmus) fed with or without 0.2% KDF inclusion during grow-out culture in intensive ponds, Mekong Delta, Vietnam (n=100)

Potassium diformate (KDF) promotes growth and health performance of striped catfish (Pangasius hypophthalmus) in commercial fishponds in the Mekong Delta, Vietnam - Image 1

Figure 2: Vietnamese intensively farmed Pangasius receive non-antibiotic feeds to quality for EU exports

This article was previously published at Aquafeed.com- Advances in Processing and Formulation". Engormix.com thanks the author and the magazine for this contribution.

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Potassium diformate for catfish

Potassium diformate (KDF) promotes growth and health performance of striped catfish (Pangasius hypophthalmus) in commercial fishponds in the Mekong Delta, Vietnam

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