Growth and fatty acid composition of Nile tilapia <i>Oreochromis niloticus</i> L. fed Azolla-diets, in tanks and in earthen ponds: A comparative study

Abstract

Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean weight: 16.3 g) fed Azolla, as partial replacement for fish meal (FM). Diets were isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ•g −1) containing 0% (A 0), 10% (A 10), 20% (A 20), 30% (A 30), 40% (A 40) and 50% (A 50) of Azolla meal (AM) respectively. Diet A 0 , without AM, acted as a control. In both experiments, fish growth decreased as AM level increased in diets (P < 0.05), and values were significantly higher (P < 0.001) in ponds than in tanks (ranges: 88.8-135.9 g vs. 51.0-88.3 g). Some dissimilarity was noticed in fish FA composition. FA profiles in fish fed in tanks was influenced by diet, except for the high content in arachidonic acid (20:4n-6) in fish fed high AMdiets. On the contrary, FA profile in fish fed in ponds was different from that in fish fed in tanks, and from diets. The lower resemblance of fish composition was more pronounced in fish fed high AM (A 30-A 50). Interestingly, those fish were rich in eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Consequently, the n-3/n-6 values decreased in tanks, whereas an increasing trend was found in ponds, and values were significantly higher in ponds than in tanks (0.35-0.53 vs. 0.08-0.17). The results suggest raising Nile tilapia with Azolladiets in ponds to improve growth and produce fish with a better FA composition, for the wellbeing of consumers.

Supplemental effects of mixed ingredients and rice bran on the growth performance, survival and yield of Nile tilapia, Oreochromis niloticus reared in fertilized earthen ponds

“…The results further showed statistically comparable phytoplankton biomass and abundance between the ponds under MI and RB treatments. These findings are in agreement with the results reported by Abou et al (2013) for O. niloticus reared in ponds and fed a plant-based diet ( Azolla spp.). The comparability in composition, biomass and abundance of phytoplankton in the ponds is due to similar diets and fertilization rates used.…”

“…Lipids contain more energy per unit weight than protein and carbohydrates (Jauncey 1998), are used efficiently as energy sources (De Silva and Anderson 1995) and are digested and metabolized easily by fish (Doreau and Chilliard 1997). Previous studies have established that, proper nutrient composition of feeds is a primary factor required for survival, muscle development and growth performance of O. niloticus (Abou et al 2013; Valente et al 2013; Ferdous et al 2014; Wijaya et al 2015). Accordingly, the slight differences in protein and lipid between the two diets used ensured similar survival, condition factor and growth of O. niloticus because they balanced their effect.…”

“…O . niloticus is known to feed on phytoplankton available in the water when cultured in semi-intensive earthen ponds (Abou et al 2013). The high nutritional value of phytoplankton in ponds generally account for a large share of total fish survival, condition factor and growth.…”

Morphology and muscle gene expression in GIFT and Supreme Nile tilapia varieties reared in two cultivation systems

“…Ribeiro et al (2011) found a greater accumulation of crude protein in tilapia muscle grown in earthen ponds compared with those reared in concrete tanks. Abou et al (2013) observed that O. niloticus receiving the same diet had a higher average final weight in earthen pond cultivation when compared to concrete tank cultivation. As these characteristics relate to muscle growth, it is possible that the availability of natural food in earthen ponds in the present study influenced the higher incidence of hypertrophic growth.…”

“…Concrete tanks and earthen ponds are employed for tilapia culture. Earthen ponds are more advantageous than concrete tanks due to the greater availability of natural feed, which may positively affect performance and other production characteristics (Ribeiro et al, 2011;Abou et al, 2013). This may be related to increased muscle growth and to several other factors related to growth, such as myostatin.…”