Effects of Dietary Protein and Lipid Levels on Growth, Body Composition, Blood Biochemistry, Antioxidant Capacity and Ammonia Excretion of European Grayling (Thymallus Thymallus)

Abstract

Background: This study evaluated growth, body composition, blood biochemistry, antioxidant capacity, innate immunity and ammonia excretion of European grayling (Thymallus thymallus) fed diets containing different protein and lipid contents. Six diets were produced to contain 30, 40 or 50% protein with 10 or 20% lipid and fed to triplicate groups (100 fish per replicate) of fish (25.2 ± 0.28 g) to visual satiety twice daily for 12 weeks. Results: Fish growth was enhanced (P ˂ 0.05) as protein increased from 30 to 40% and plateaued thereafter. Enhancing protein and lipid content of diet led to reduced feed intake and improved feed efficiency. Moreover, protein efficiency ratio increased at higher lipid level while lower values were recorded at higher protein levels. Increasing dietary lipid content led to the enhancement of viscerosomatic index and intraperitoneal fat ratio. An interaction of protein and lipid was found on whole-body lipid, and muscle lipid was responsive to dietary lipid level. Muscle ARA, EPA and Ʃn-6 LC-PUFA contents enhanced by increasing dietary protein level. Moreover, increasing fat content of diet led to enhanced muscle linoleic acid, linolenic acid, ƩMUFA, Ʃn-6, DHA/EPA and n-6/n-3. However, EPA, DHA, Ʃn-6 LC-PUFA, Ʃn-3, Ʃn-3 LC-PUFA and EPA/ARA decreased at higher dietary lipid level. Serum triglyceride (TG) concentration and lactate dehydrogenase (LDH) activity decreased as dietary protein level increased while an opposite effect was observed for cholesterol (CHO) concentration. Increasing fat content of diet led to enhanced serum TG, CHO and glucose concentrations and reduced alanine aminotransferase, aspartate amino transferase and LDH activities. Serum malondialdehyde concentration was enhanced by increasing both dietary protein and lipid contents. Furthermore, serum myeloperoxidase activity was enhanced at higher dietary lipid level. Water total ammonium nitrogen (TAN) concentration was measured after 5 and 24 h of last feeding, and the results indicated the reduction of ammonia excretion as dietary lipid content increased. Conclusions: These findings suggest that 40% dietary protein can support optimal growth of juvenile European grayling and increasing lipid content from 10 to 20% can improve feed utilization and reduce ammonia excretion to the rearing water.

Fine ultrastructural features of germ cells and spermatozoa during spermatogenesis in the European grayling, Thymallus thymallus (Teleostei, Salmoniformes, Salmonidae)

“…Because fish fauna is highly diverse, information on the ultrastructural characteristics of spermatogenesis in teleosts is limited to a few species (6, 25). The ultrastructure of grayling spermatozoa has been previously described by Lahnsteiner (22), but the authors did not provide detailed information on the associated cells, such as spermatogenic cells, Sertoli and Leydig cells in this species. Therefore, in this study we have attempted to describe the ultrastructural characteristics of the spermatogenic cell in different stages of development and spermatozoa of the European grayling.…”

“…This species is considered an ecologically valuable bioindicator of water contamination, local habitat, and food supply (18,19). The European grayling is very popular for sport fishing, and its population has been supported by a long sustainable stocking program, including broodstock management (20) and reproduction (21), and larval and juvenile culture under controlled conditions (22,23). In this regard, understanding the spermatogenic process and spermatozoa development in the European grayling are important for increasing the knowledge about the reproduction and reproducibility of this species.…”

Efecto de la ración alimentaria en la acumulación amonio y supervivencia de Dormitator latifrons

“…La cantidad y calidad de las proteínas consumidas por los peces, asociada a la cantidad de energía requerida y al tamaño corporal de los organismos, son algunos factores que influyen en la cantidad de amonio no ionizado (NH 3 ) que se produce en el cuerpo de los peces y es excretado por las branquias (4,5). A su vez, el éxito de esta excreción depende de la cantidad de amonio no ionizado en el agua, la cual debe ser baja para que se genere un gradiente que permita la difusión pasiva de este gas soluble desde la sangre hacia el agua (4,6).…”

Protein-sparing effects of lipids in the diet of golden pompano (Trachinotus ovatus): evaluation of growth, feed utilization, and lipid metabolism

“…As reported, high levels of TG, CHO, and LDL were found to be associated with impaired lipid transport and poorer health conditions(Hossain et al 2016). As dietary lipid levels increased, increment of serum TG, CHO, and LDL concentrations were con rmed in rock sh(Li et al 2023), European grayling(Rahimnejad et al 2021), and crucian carp(Ding et al 2022). In our case, the relatively high levels of CHO, HDL and LDL were presented in the sh fed diets with high lipid levels, while high TG levels were also found in the sh fed diets with low protein levels.…”