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Citric acid and phytase supplementation on canola meal for rohu fingerlings


The outer view of fish rearing tanks (A) and faeces collection tube (B). Photo: Maryam Iqbal et al., Aquaculture Reports

Positive interaction between citric acid (CA) and phytase (PH) could improve the growth performance of rohu (Labeo rohita) fingerlings. 

A study conducted at the University of Agriculture, Faisalabad, Pakistan showed that supplementation of CA and PH in canola meal improved growth performance, nutrients digestibility, and body composition of the fish. The best performance was observed at the supplementation of 30 g/kg CA+1,000 FTU/kg PHY. 

Maryam Iqbal et al. investigated the suitability of canola meal as a dietary protein source along with the combined effects of dietary CA and PHY supplementation on growth performance, nutrient digestibility, and body composition of the species.

“The dietary acidification stimulates the activity of digestive enzymes in fish gut and optimizes the digestion and utilization of nutrients and minerals. Additionally, acidification provides favourable environmental conditions for phytase to diminish the level of phytate in digesta, thus basically inhibits the formation of phytate-protein–mineral complexes,” the authors said in the study, “Combined effects of citric acid and phytase supplementation on growth performance, nutrient digestibility and body composition of Labeo rohita fingerlings.” It was published in Aquaculture Studies.

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Canola meal has high animal proteins and low anti-nutrient factors, making it a “promising alternative” to animal protein. The anti-nutrient factors, however, are seen as a drawback in researches for plant-based proteins inclusion in aquafeeds. Anti-nutrient factors may prevent absorption of nutrients.

Phytate has the tendency to build insoluble complexes with minerals, protein, carbohydrates, lipids, and vitamins in the guts of fish, thereby making them unavailable to the fish, they explained.

During the 90-day study, fingerlings were hand-fed with assigned diets every day, once in the morning and once in the afternoon, at three per cent body weight. Spraying method was used for supplementation of phytase.

The best diet formulation, which was at 30 g/kg CA+1,000 FTU/kg PHY, performed significantly better compared to control, which didn’t have CA and PHY supplementation.

The three other diets had 15 g/kg CA +PHY 1,000 FTU/kg, 15 g/kg CA +PHY 2,000 FTU/kg, and 130 g/kg CA +PHY 2,000 FTU/kg.

The best formulation’s percentage weight gain was almost 210 per cent, feed conversion ratio was 1.12 and specific growth rate, 3.06 per cent. Control’s was 70 per cent, 2.40, and 1.79 per cent, respectively.

Rohu, an Indian major carp species, is a major aquacultured fish in South Asia. It grows to an average of about half metre but adults can reach as much as two metres-long and 45 kg. 


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