Changes in the physiological parameters, fatty acid metabolism, and SCD activity and expression in juvenile GIFT tilapia (Oreochromis niloticus) reared at three different temperatures

Abstract

We evaluated the effects of rearing temperature on the composition of fatty acids and stearoyl-CoA desaturase (SCD) activity and gene expression in GIFT (genetically improved farmed tilapia) tilapia. Three triplicate groups of fish were reared for 40 days at 22, 28, or 34 °C. At the end of the trial, the final body weight of juveniles reared at 28 °C was higher than that of fish reared at 22 or 34 °C. Feed intake, feed efficiency, and the protein efficiency ratio were also higher at 28 °C. The fatty acid composition of muscle tissue differed significantly (P < 0.05) among the treatment groups. The content of SFA decreased with decreasing temperature, whereas the UFA content increased. We observed high levels of PUFA, particularly n-3 PUFAs, in fish reared at the lower temperature. Rearing at low temperature significantly (P < 0.05) increased the expression and activity of the SCD gene. Increased SCD activity and gene expression can increase the biosynthesis of MUFAs in GIFT tilapia muscle. Additionally, cold acclimation can decrease the content of TC and TG in GIFT tilapia, which can help increase cold tolerance.

The effect of dietary bamboo charcoal supplementation on growth and serum biochemical parameters of juvenile common carp (Cyprinus carpioL.)

“…For instance, a significant rise in serum enzyme activity (AST, ALT and ALP) may be an indication of liver damage including degeneration of the liver, necrosis and/or cellular damage (Akrami, Gharaei, Mansour, & Galeshi, ; Wang et al., ), which may result from the toxicity of certain dietary ingredients used in the formulation of experimental diets. On the other hand, elevated levels of TC, TG and LDL in the serum are considered an indicator of compromised health and immunity due to production and accumulation of excess amounts of reactive oxygen species (ROS; Ma, Qiang, He, Gabriel, & Xu, ). TP is used as an indicator of the nutritional and metabolic state of fish and is also considered an indicator of nonspecific immunity (Habte‐Tsion, ) while increased glucose as indicator of stress.…”

“…Ma et al. () suggested that patterns of TC and HDL in the serum are likely to be correlated due to the fact that TC which exists in serum lipoprotein is transported from the artery walls to the liver for metabolism, therefore, with an increase in TC levels one can also expect an increase in HDL. This notion was certainly noted in this study as we found that both TC and HDL were significantly elevated at 0.5% BC supplementation, though TC was significantly improved at 2% BC supplementation.…”

Preferential Partitioning of Rumen‐Protected n‐3 and n‐6 Fatty Acids into Functionally Different Adipose Tissues

“…Accordingly, the subcutaneous AT was found to have a greater MUFA proportion than the intramuscular fat (Sturdivant et al, ). Stearoyl‐CoA desaturase (SCD) is an enzyme abundant in animal tissues that converts 18:0 into 18:1 n‐9 (Ma et al, ; Sturdivant et al, ). It can be stimulated by low temperatures (Hsieh et al, ; Ma et al, ) and is closely related to changes in MUFA proportions (Hsieh et al, ).…”

“…Stearoyl‐CoA desaturase (SCD) is an enzyme abundant in animal tissues that converts 18:0 into 18:1 n‐9 (Ma et al, ; Sturdivant et al, ). It can be stimulated by low temperatures (Hsieh et al, ; Ma et al, ) and is closely related to changes in MUFA proportions (Hsieh et al, ). The SCD activity was shown to be especially great in subcutaneous AT of cattle (Chang et al, ; St. John et al, ), most likely to counterbalance the rumen biohydrogenation activity and increase MUFA proportions in subcutaneous AT.…”

Content of highly unsaturated fatty acids in fish from rivers of contrasting temperature

“…Nevertheless, in some fish, the HUFA levels measured as total lipids respond well to temperature changes, for example, in rainbow trout O. mykiss , salmon Salmo salar , and tilapia Oreochromis niloticus (Arts et al, ; Calabretti et al, ; Ma, Qiang, He, Gabriel, & Xu, ). In addition, temperature may also affect the ratio between phospholipids and neural lipids, although the total fat content in fish flesh remains constant (Calabretti et al, ).…”