Comparative biochemical composition of wild and farm origin grayling (Thymallus thymallus) eggs

Abstract

In this study, the biochemical composition of wild and farm origin grayling eggs was compared, first, to evaluate the composition of fatty acids and protein content in grayling eggs for the first time, and second, to discover differences in biochemical composition between wild and farm origin eggs which is affected by broodstock feed. Farm origin grayling females were fed commercial trout starter feed, while wild origin females were feeding on food present in their natural environment. Fatty acid composition, protein content and colour were determined. Based on a principle component analysis (PCA) of the biochemical profile, farm and wild origin grayling eggs were clearly separated. Wild origin grayling eggs contained higher amount of SFA, but lower MUFA and PUFA than farm origin eggs. A considerable difference between wild and farm origin grayling eggs was observed also in essential fatty acids: C22:6 n-3 (DHA), C20:5 n-3 (EPA) and C20:4 n-6 (ARA), resulting in higher EPA/ARA and DHA/EPA ratio in farm origin eggs compared to wild origin eggs. Wild origin grayling eggs were characterised by higher protein content and were more intensely red-coloured than farm origin eggs, which were almost colourless. It could be concluded that the biochemical composition of farm origin eggs significantly differs from wild origin grayling eggs, which might have an influence on the embryonic development and hatching success of farm origin grayling. Therefore, the diet that has the greatest effect on egg composition needs to be optimised to meet the needs of the grayling broodstock and to improve the breeding efficiency of farm raised graylings.

HIGHLIGHTS

• Biochemical composition of grayling eggs differs significantly between the two lifestyles (wild and farm origin).

• Differences in the proportion of essential fatty acids: DHA, EPA and ARA.

• Suboptimal EPA/ARA and DHA/EPA ratios in farm origin eggs.

Keywords:

• Salmonidae
• fatty acid
• reproduction
• egg quality
• conservation

Acknowledgements

The authors thank technical assistant Ivana Štular from Head of nutrition for her assistance with laboratory analyses, Erik Sivec from Soča fish farm (Kobarid, Fisheries Research Institute of Slovenia) for his help with grayling rearing and gamete collection and colleagues from Fisheries Research Institute of Slovenia, fishing clubs Bistrica and Bled for organizing field sampling. The authors acknowledge the financial support of the Slovenian Research Agency (Research core funding No. P4–0220) and Ministry of Education, Science and Sport of the Republic of Slovenia.

Disclosure statement

The authors report there are no competing interests to declare

Data availability statement

The data presented in this study are available on request from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported by the Slovenian Research Agency (Research core funding No. P4–0220) and Ministry of Education, Science and Sport of the Republic of Slovenia.