Effects of dietary protein and lipid levels on growth performance, fatty acid composition and antioxidant-related gene expressions in juvenile loachMisgurnus anguillicaudatus

Abstract

Dojo loach (Misgurnus anguillicaudatus) is one of the most important cultured freshwater fish in several East Asian countries. However, a little information is available in its nutritional requirements. Thus, this study was conducted to evaluate the effects of feeding varying levels of dietary protein and lipid on growth, fatty acid composition and antioxidant‐related gene expressions in juvenile loach. Six practical diets at three levels of protein (30%, 40% and 50%) and two levels of lipid (6% and 12%) were fed to loach juveniles (initial weight 0.40 g) in triplicated groups (20 fish per replicated) for a period of 8 weeks. Results showed that regardless of lipid level, body weight gain of fish was significantly increased with incremental dietary protein level. Meanwhile, feed conversion ratio was significantly decreased by dietary protein levels, and the lowest value was observed in fish fed dietary protein levels of 50%, regardless of dietary lipid level. Moreover, the percentage of 22:6n‐3 in viscera was significantly increased by different protein levels. The expression level of catalase was significantly increased with incremental dietary protein level with both lipid levels. Meanwhile, the expression level of hepatic nuclear factor erythroid 2‐related factor 2 (Nrf2) was downregulated with incremental dietary protein level with 6% of lipid level, but the expression was upregulated with incremental dietary protein level with 12% of lipid level. In conclusion, these data suggested that 6% lipid and 50% protein in diet was optimal for loach during early development stage.

Dietary protein:lipid ratio changes growth, digestive enzyme activity, metabolic profile and haematological parameters in hybrid surubim (Pseudoplatystoma fasciatum × Leiarius marmoratus)

“…This fact is evident when the growth parameters of the 9.00 and 1.78 protein:lipid ratio treatments are compared in the study. Similar results on growth parameters were observed for juvenile Siberian sturgeon (Babei, Abedian-Kenari, Hedayati & Yasdani-Sadati, 2017) and Dojo loach, Misgurnus anguillicaudatus (Yan et al, 2017) fed different protein and carbohydrate:lipid levels. Growth of Totoaba macdonaldi, a marine fish, was affected by low feed consumption in treatments with high lipid levels (Perez-Velasquez, Minjarez-Osorio & Gonzales-Felix, 2017).…”

Beneficial roles of feed additives as immunostimulants in aquaculture: a review

“…; Yan et al . 2017b). More than half of the AA consumed by fish may be deposited into body protein, and the requirement of essential AA corresponds to the AA tissue content (Kaushik & Seiliez ).…”

“…Dietary AA are crucial for fish as energy substrates, for endogenous protein synthesis and to regulate metabolic pathways (Andersen et al 2016;Yan et al 2017b). More than half of the AA consumed by fish may be deposited into body protein, and the requirement of essential AA corresponds to the AA tissue content (Kaushik & Seiliez 2010).…”

The dietary zinc requirement of a benthic fishParamisgurnus dabryanus

“…In recent years, its market demand is gradually increasing in East Asian countries (Cho, Kim, Kim, & Nam, 2012). So far, the dietary requirement of various amino acids, fatty acids and some vitamins have been studied (Gao et al, 2014;Yan et al, 2017). However, the dietary zinc (Zn) requirement for this species has not been reported yet.…”