Somatic indices and nutritional composition of the roe of the native fish Dormitator latifrons: no aplica

Objective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA. Keywords: proximate composition, fatty acids, essential amino acidsObjective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA

Growth, ammonium excretion, and oxygen consumption of hybrid red tilapia (Oreochromis mossambicus × Oreochromis aureus) grown in seawater and freshwater

In a comparative study using the hybrid tilapia Oreochromis mossambicus × Oreochromis aureus grown in seawater and freshwater, no significant differences in growth performance (weight gain) and biological indices (e.g., feed conversion efficiency and survival) was observed after 90 days of experimentation. A common feed was formulated to contain 40% crude protein and 8.5% crude fat. Fish meal and poultry by-product meal (50:50) were used as a source of protein in the formulation. The study was conducted using recirculation systems and organisms already adapted to seawater and freshwater with an initial weight of 25.0 ± 0.06 g and 24.70 ± 0.32 g, respectively (four replicates per treatment); at the end of the experiment their final weight was 161.80 ± 12.78 g and 167.60 ± 7.29 g, respectively. The thermal growth coefficient was 0.91 and 0.89 (seawater vs freshwater), and there were no significant differences; however, the apparent digestibility of dry matter as well as per nutrient (protein, lipid, and carbohydrate) was significantly higher for the organisms in the seawater treatment. The digestibility could be associated with greater enzymatic activity in the presence of higher ionic strength. The respirometric study indicated that the O:N ratios were similar for organisms reared in seawater and freshwater, with values of 21 and 18, respectively. This indicates that this strain of tilapia uses a mixture of proteins and lipids as energy substrates. We conclude that this strain of tilapia has the potential to adapt and thrive in a marine environment and that its production practices could be expanded

Metabolism of Seriola lalandi during Starvation as Revealed by Fatty Acid Analysis and Compound-Specific Analysis of Stable Isotopes within Amino Acids.

Fish starvation is defined as food deprivation for a long period of time, such that physiological processes become confined to basal metabolism. Starvation provides insights in physiological processes without interference from unknown factors in digestion and nutrient absorption occurring in fed state. Juveniles of amberjack Seriola lalandi were isotopically equilibrated to a formulated diet for 60 days. One treatment consisted of fish that continued to be fed and fish in the other treatment were not fed for 35 days. The isotopic signatures prior to the beginning of and after the starvation period, for fish in the starvation and control treatments, were analysed for lipid content, fatty acid composition and isotopic analysis of bulk (EA-IRMS) and of amino acids (compound specific isotope analysis, CSIA). There were three replicates for the starvation group. Fatty acid content in muscle and liver tissue before and after starvation was determined to calculate percent change. Results showed that crude lipid was the most used source of energy in most cases; the PUFAs and LC-PUFAs were highly conserved. According to the protein signature in bulk (δ15N) and per amino acid (δ13C and δ15N), in muscle tissue, protein synthesis did not appear to occur substantially during starvation, whereas in liver, increases in δ13C and δ15N indicate that protein turnover occurred, probably for metabolic routing to energy-yielding processes. As a result, isotopic values of δ15N in muscle tissue do not change, whereas CSIA net change occurred in the liver tissue. During the study period of 35 days, muscle protein was largely conserved, being neither replenished from amino acid pools in the plasma and liver nor catabolized

¹⁵N enrichment of individual amino acids in liver and muscle tissue of <i>S</i>. <i>lalandi</i> fed a commercial diet.

<p>¹⁵N enrichment of individual amino acids in liver and muscle tissue of <i>S</i>. <i>lalandi</i> fed a commercial diet.</p

Starvation-induced net changes in ¹⁵N enrichment of individual amino acids in liver and muscle tissue of <i>S</i>. <i>lalandi</i> after 35 days of starvation.

<p>Starvation-induced net changes in ¹⁵N enrichment of individual amino acids in liver and muscle tissue of <i>S</i>. <i>lalandi</i> after 35 days of starvation.</p

Amino acid profile from control diet used to equilibrate the isotopic signature of <i>S</i>. <i>lalandi</i> and used by the control group.

<p>Amino acid profile from control diet used to equilibrate the isotopic signature of <i>S</i>. <i>lalandi</i> and used by the control group.</p

Compound specific δ¹⁵N of amino acids of of <i>S</i>. <i>lalandi</i> liver tissue: Commercial diet, Time 0, Liver 35 d starvation and Liver 35 d fed, average and standard deviation.

<p>Asterix (*) denotes statistically significant difference between time 0 and 35 days of starvation.</p

δ¹³C (‰) in bulk muscle and liver tissues of <i>S</i>. <i>lalandi</i> during 35 days of starvation.

<p>Liver starvation, Muscle starvation, Liver control and Muscle control, average and standard variation.</p

Total weight loss and crude fat content from muscle and liver tissues of <i>S</i>. <i>lalandi</i> before and after 35 days under starvation (n = 3) compared to the fed group (control).

<p>Initial samples were pool together (n = 6).</p

Compound specific δ¹⁵N of amino acids of <i>S</i>. <i>lalandi</i> muscle: Commercial diet, Time 0, Muscle 35 d starvation and Muscle 35 d fed, average and standard deviation.

<p>Asterix (*) denotes statistically significant difference between time 0 and 35 days of starvation.</p