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The apparent digestibility coefficients (ADCs) of Tenebrio molitor meal (TMM), Hermetia illucens meal (HIM), Clostridium autoethanogenum protein (CAP), Methylococcus capsulatus meal (MCM), Chlorella vullgaris meal (CVM), Cottonseed protein concentrate (CPC) and Peruvian fishmeal (PFM) were determined in juvenile hybrid grouper (Epinephelus fuscoguttatus♀xEpinephelus lanceolatu♂). A basal diet (including 50% fishmeal) and seven test diets (700 g/kg of the basal diet and 300 g/kg of each test ingredient) were formulated with 0.1% yttrium oxide (Y2O3) as an inert marker. The juvenile hybrid groupers, with initial average body weight of (9.95±0.50) g, were randomly distributed into 0.3 m³ fiberglass tanks, each tank with 30 fish. The faeces samples were collected twice-daily by siphoning following feeding fish after five days of domestication. The ADCs of dry matter of seven test ingredients were ranked as CVM>TMM=CAP=CPC>HIM=MCM=PFM (P<0.05). CVM showed the highest ADCs of dry matter (DM), crude protein (CP) and most amino acids (including methionine and threonine) except crude lipids (CL), whereas HIM had the relatively lower ADCs of DM, CP and most amino acids except CL. CAP had a higher lysine digestibility than the other six test ingredients, and was only lower than CVM in the ADC of CP. The ADC of DM in PFM was significantly lower than that in CVM (P<0.05), and showed no differences with that in CAP (P>0.05). Besides, PFM showed a lower ADC of CP than the ADCs of CP in CVM, CAP and MCM (P<0.05), and showed a lower ADC of lysine than that in CAP as well as a lower ADC of threonine than those in CAP and CVM (P<0.05). Overall, this study showed the advantage of CVM and CAP among the seven protein sources on the digestibility of feed available in hybrid grouper. [ABSTRACT FROM AUTHOR]

This experiment was conducted to investigate the effects of dietary black soldier fly (Hermetia illucens) larvae meal on growth performance, non-specific immunity and lipid metabolism of Litopenaeus vannamei. The control diet (FM) contained 25% fishmeal and then 10% (BSF10), 20% (BSF20) and 30% (BSF30) of fishmeal protein were replaced by black soldier fly larvae meal to formulate four isonitrogenous and isolipidic diets. Shrimps with an initial body weight of (0.88±0.01) g were fed four times daily for 7 weeks. Results showed that there were no significant differences in growth performance of shrimp fed BSF10 and BSF20 diets compared to FM group (P>0.05), but the growth performance of the shrimp in the BSF30 group significantly reduced (P<0.05). The whole shrimp crude lipid content was significantly lower in the BSF20 and BSF30 groups, and the hemolymph triglyceride and total cholesterol levels were significantly lower in the BSF30 group compared to FM group (P<0.05), but there were no significantly different in crude lipid of hepatopancreas among the four groups (P>0.05). The activities of hemolymph alanine aminotransferase and aspartate aminotransferase significantly decreased in the BSF10, BSF20 and BSF30 groups compared to FM group (P<0.05). The total antioxidant capacity of BSF20 group was significantly higher than that of the other groups, and superoxide dismutase activity of BSF10 group was significantly higher than that of FM group (P<0.05). The hepatopancreas acid phosphatase and alkaline phosphatase activities were significantly lower in the BSF30 group than that in the FM group (P<0.05). The lipase activity of BSF30 group was significantly lower than BSF10 group (P<0.05). The fatty acid synthase activity in BSF10 and BSF20 groups was significantly higher than that in FM group, the carnitine palmitoyl transferase activity in BSF20 group was significantly higher than the other three groups, and the activity of isocitrate dehydrogenase in BSF30 group was significantly higher than that in FM group (P<0.05). The activities of hemolymph lipid triglyceride lipase and α-ketoglutarate dehydrogenase in BSF10, BSF20 and BSF30 groups were significantly higher than those in FM group (P<0.05). To conclude, replacing 10% or 20% of fishmeal with black soldier fly larvae meal had no negative effect on the growth performance of Litopenaeus vannamei, improved the antioxidant capacity of shrimp and reduced the hemolymph glutamate transaminase and glutamic acid transaminase activities. The crude lipid of whole shrimp significantly reduced in BSF20 group, and when the replacing level reached to 30%, the activity of enzymes related to lipid catabolism and tricarboxylic acid cycle was significantly increased, which further promoted the lipid metabolism of shrimp. [ABSTRACT FROM AUTHOR]

A 5 × 3 factorial growth trial was conducted to evaluate optimal dietary protein and lipid levels (dietary protein level, DP; dietary lipid level, DL) for juvenile Sillago sihama (S. sihama) (2.0 ± 0.02 g, initial weight). Fish were fed 15 diets containing 5 DPs (350, 400, 450, 500 and 550 g/kg) and 3 DLs (60, 90 and 120 g/kg) for 8 weeks. The interaction between proteins and lipids significantly influenced the feed conversion ratio, condition factor, body composition, antioxidant indices and lipase activity (p <.05). DP 450 g/kg showed the highest average final body weight. DPs 500 and 550 g/kg significantly decreased the protein efficiency ratio (p <.05). DL 120 g/kg showed the highest percentage weight gain. The low feed conversion ratio was found in diets P45L12, P55L9 and P55L12. Diet P45L12 showed high superoxide dismutase activities. DP 450 g/kg showed the lowest average malondialdehyde content. Lipase activity was increased by increasing DP (p <.05) with a fall at DP 550 g/kg. Under the present experimental conditions, the optimal DP for S. sihama was 450 g/kg under the DL 120 g/kg. [ABSTRACT FROM AUTHOR]

Phosphoenolpyruvate carboxykinase (PEPCK) is known to exist as mitochondrial (PEPCK‐M) and cytosolic isoforms (PEPCK‐C). They are involved in glucose production and play vital roles in regulating glucose homeostasis. This study aimed to (1) clone and characterize PEPCK‐C cDNA from golden pompano fish (Trachinotus ovatus), which are known to have poor utilization of dietary carbohydrates, and (2) analyze the regulation of its expression by varying dietary carbohydrate‐to‐lipid ratios and nutritional status. A full length golden pompano PEPCK‐C cDNA fragment of 2,652 bp was cloned, which contains an open reading frame of 1,875 bp encoding 624 amino acids and shows a high homology to cobia (Rachycentron canadum) PEPCK‐C sequence (92% similarity). The analysis of tissue distributions of PEPCK‐C mRNA showed that a high abundance of PEPCK‐C was expressed in golden pompano liver, followed by kidney; while lower expression levels were found in the heart and intestine. In liver, PEPCK is under the regulation of dietary composition and nutritional status at the enzymatic and molecular levels. Our results indicate that PEPCK‐C plays a modulating role in the adaptation of hepatic gluconeogenesis to different nutrient conditions. Thus, the absence of molecular inhibition of gluconeogenic PEPCK gene expression in rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata), which can at least partially account for their poor utilization of dietary carbohydrate, is specific to these species and is not observed in golden pompano. Further studies that examine, at the enzymatic and molecular levels, other key enzymes involved in hepatic glucose metabolism are necessary to understand the poor utilization of carbohydrates in golden pompano. [ABSTRACT FROM AUTHOR]

Unlike the case of mammals, teleost fish generally have poor ability to utilize carbohydrate, and the clearance of glucose from the plasma is sluggish. In this study, after a 8‐week feeding trial, we conducted a glucose tolerance test to hypothesize that the capability of grass carp (Ctenopharyngodon idellus) to clear a glucose load is associated with its nutrient history of different carbohydrate‐to‐lipid ratio diets (CHO:L: 1.52%, 5.84% and 34.84%) through glycogen synthesis and glucose metabolic key enzymes. Our results showed that after a glucose load, the plasma glucose of fish fed with high CHO:L‐ratio diet (34.84%) first declined to baseline conditions, and the peak value of liver and muscle glycogen content was significantly higher in high CHO:L‐ratio but lower in low CHO:L group (1.52%). In addition, after glucose administration, hepatic GK (glucokinase) activity of fish fed with high CHO:L‐ratio diet increased more significantly than that of the other groups, and PEPCK (phosphoenolpyruvate carboxykinase) activity obviously decreased in low CHO:L‐ratio group. The results indicated that a long‐term adaptation to the high CHO:L‐ratio diet can improved the glucose tolerance of C. idellus through the promotion of glycogen synthesis and GK activity. [ABSTRACT FROM AUTHOR]

In this paper, the glucose tolerance tests (GTT) were performed to evaluate the effects of three dietary carbohydrate levels on growth, plasma glucose, hormones (insulin and IGF‐I), glucose homeostasis and GLUT4 gene expression of Tilapia nilotica. Juvenile tilapia (av. wt.10 g) were randomly distributed into three groups with three replicates and fed for 8 weeks with three dietary carbohydrate levels: 40% (CH), 30% (CM) and 20% (CL). After 8 weeks of feeding trial, fish were injected with glucose (30 mg/100 g body weight) for GTT. The growth performance results showed the survival rate in the CH group was significantly lower than the other two groups (p < 0.05). The GTT results showed that the plasma glucose level positively correlates with the diets' carbohydrate level initially, peaked at 1 hr and declined thereafter. The plasma IGF‐1 levels were positively correlated with diets' carbohydrate levels; first the levels increase and then decrease after injection in all the three groups. There was a direct relationship between the carbohydrate levels and the activities of liver pyruvate kinase (PK) and glucokinase (GK) enzymes. Muscle GLUT4 expression in groups changed slightly in 0–3 hr and then increased sharply during 6–12 hr. Results of this study indicated that the moderate dietary carbohydrate level may improve the glucose tolerance of T. nilotica. The carbohydrate levels can affect plasma glucose, IGF‐1 and GLUT4 expression in T. nilotica. In addition, the IGF‐1 may play a more important role on the glucose metabolism than insulin. The delayed gene transcription of GLUT4 may be one of the reasons for glucose intolerance in T. nilotica. [ABSTRACT FROM AUTHOR]

Abstract: A 70‐day experiment was implemented to study the iron (Fe) bioavailability of three Fe sources in Epinephelus coioides (initial weight, 12.19 ± 0.14 g). Treatments consisted of 0, 50, 90, 130, 170 and 210 mg supplemental Fe/kg from iron sulphate (FeSO4), ferric citrate (Fe‐citrate) and hydroxy methionine analogue iron (Fe‐MHA). The results showed that the growth performance was not affected by Fe level regardless of Fe sources. Hepatic catalase activity (CAT), the haematocrit value (Hct), haemoglobin (Hb), mean corpuscular volume (MCV) and Fe content in whole body or liver firstly increased significantly and then plateaued as Fe level increased regardless of the Fe source, except significant decreasing of Hct in 210 mg Fe/kg group from FeSO4. Manganese (Mn) content decreased significantly and then kept stable in the whole body and liver whatever the source was. The slope‐ratio method using FeSO4 as the reference and Hb content, CAT activity, body and hepatic Fe concentration as the response parameter showed the average relative bioavailability of Fe‐citrate and Fe‐MHA was 103.25 ± 4.35 (n = 4) and 134.5 ± 15.67 (n = 4), respectively, with the maximum value of Fe‐MHA in any case. In conclusion, Fe‐MHA was the most effective to meet preferable haematological index, CAT activity and mineral deposition, with little difference between Fe‐citrate and FeSO4, athough Fe levels with different sources failed to influence the growth in grouper. [ABSTRACT FROM AUTHOR]

Abstract: An experiment was implemented to study the effect of dietary zinc levels from three zinc sources on growth performance, immunity, and tissue mineral elements deposition on juvenile grouper. Based on the zinc free feeds, dietary zinc levels of 0, 10, 20, 40, 80, and 160 mg/kg were added from zinc sulphate (ZnSO4), tetrabasic zinc chloride (TBZC), and 2‐hydroxy‐4‐(methylthio) butyrate zinc (Zn‐HMB). The results of the 8‐week study indicated that the weight gain rate (WGR) and specific growth rate (SGR) at level 10 mg/kg were significantly higher than the control fed and the reached a plateau until level 80 mg/kg, when the sources were ZnSO4 and Zn‐HMB. WGR and SGR decreased significantly at level 160 mg/kg compared to 80 mg/kg in group TBZC. Feed coefficient (FCR) of all zinc source groups showed trend of decrease before rising. The alkaline phosphatase (AKP) in serum, catalase (CAT), total superoxide dismutase (SOD), copper‐zinc superoxide dismutase (Cu‐Zn SOD) in liver and zinc concentrations in whole body and vertebrae increased significantly than those in control group and then kept steadily in all treatments. Regardless of the sources, the manganic content of whole body or vertebra showed a downtrend. Based on the WGR, the dietary zinc requirements in juvenile grouper were 52.94 mg/kg from ZnSO4. The average relative bioavailability (RBV) of TBZC and Zn‐HMB was 169.33% and 200.33%, respectively, compared to ZnSO4. [ABSTRACT FROM AUTHOR]

Abstract: A 50‐day feeding trial was conducted for juvenile pearl gentian grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀) to determine the optimal amount of Tenebrio molitor meal (TM) that could replace fishmeal (FM) in feeds without reducing growth performance, antioxidant enzyme activities and resistance. Six isonitrogenous and isolipidic diets were formulated with TM replacing 0% (T0), 6.25% (T6), 12.5% (T12), 18.75% (T18), 25% (T25), 31.25% (T31) FM respectively. Each diet was randomly divided into triplicate groups with 30 juveniles (initial weight 6.60 ± 0.00 g). After feeding trail, fish were challenged by Vibrio harveyi for 7 days. The results showed that each treatment had better survival rate between 96.67% and 100%. Fish fed with control and T6 diet showed lower final weight and weight gain rate as compared to other diets. The feed conversion ratio of fish fed on T12 and T18 diet had no significant difference compared to control diet. As compared to control diet, other diets had no significant differences on specific growth rate and temperature growth coefficient. Fish fed with T6 diet had highest liver glutathione reductase activities. No significant differences were observed in liver superoxide dismutase activities in fish fed with T6, T12, T25, T31 and control diet. Fish fed on T18 diet had lowest hepatic malondialdehyde contents and a highest relative per cent survival. According to a broken‐line model, the recommended substituted ratio of TM for FM was estimated to be 12.3% for grouper obtaining maximum WGR, corresponding to additive amount of TM is 4.92%. [ABSTRACT FROM AUTHOR]

This study was conducted to compare the effects of manganese sulphate (Mn-S), glycine manganese(Mn-Gly) and manganese 2-hydroxy-4-(methylthio)butyrate (Mn- HMB) on juvenile cobia, Rachycentron canadum L. Treatments consisted of 0, 2, 4, 8, 16 or 32 mg supplemental Mn kg−1 from Mn-S, Mn-Gly or Mn- MHB. Growth performance, manganese status, antioxidant activities and tissue mineral content were analysed after a 70-day feeding period. Specific growth rate ( SGR) increased with feeding 6.29 to 12.65 mg Mn kg−1 diet from the Mn-S or 6.86 to 12.39 mg Mn kg−1 from the Mn-Gly or 6.50 to 8.33 mg Mn kg−1 from the Mn- HMB and then plateaued above these levels. Feed conversion ratio ( FCR) show decreasing first and then increased trend. Survival rate ( SR) were not affected by the dietary treatments ( P > 0.05). Fish fed diets supplemented with manganese at levels of 4-32 mg Mn kg−1 had obviously higher hepatic Mn- SOD activity ( P < 0.05); on the contrary, hepatic has lower malondialdehyde ( MDA) content ( P < 0.05) than fish fed the basal diet. The manganese concentrations of whole body and vertebrae increased with increasing dietary Mn levels from 2-32 mg Mn kg−1 (independent on manganese sources). Dietary Mn supplementation did not significantly influence the copper concentrations of whole body and vertebrae, the zinc concentrations of whole body and liver. Analysis by the broken-line regression of SGR indicated that the optimal dietary Mn requirements in juvenile cobia were 15.42, 11.22 and 10.50 mg Mn kg−1 diet from Mn-S, Mn-Gly or Mn- HMB respectively. [ABSTRACT FROM AUTHOR]