Lipids play a vital role in fueling early developmental activities in fish, especially in building essential tissues crucial for good growth and egg quality. Although existing broodstock research has ascertained that eggs are heavily influenced by broodstock diet, there is currently no information regarding this timeline of nutritional incorporation. The objective of this study is to determine the duration required for broodstock to transfer fatty acids from their diet to the eggs.
In 2021, nine California yellowtail, Seriola dorsalis, broodstock were fed alternating diets of commercial pellets (Vitalis PRIMA: Skretting, Norway) and cut-bait diet. The diets were switched every 6 weeks and the experiment was replicated twice. Biochemical and biometric data from spawns were collected and statistically analyzed by grouping spawns based on diet type and days after diet switch.
FIGURE 1: The timeline of nutrient incorporation visualized in a piecewise regression scatterplot of LNA, LA and EPA in California Yellowtail (CYT) spawns. CYT were fed alternating diets of cutbait and Vitalis over a period of 41 days each.
Neutral fractions of the eggs were found to have incorporated higher amounts of LNA (linolenic acid) and LA (linoleic acid) from Vitalis diet, which are essential fatty acid precursors, but higher amounts of EPA (eicosapentaenoic acid), an omega-3 fatty acid, from cutbait diet (Figure 1). Most importantly, our results showed overall fatty acids from both diets were fully incorporated by both polar and neutral fraction of the eggs within just 10 days following the diet switch. This understanding of nutritional incorporation from broodstock diet to eggs will help producers develop more informed feeding plans when testing new feeds or supplementation. These findings can also encourage producers to explore the use of cutbait to more sustainable pelleted diets as well as open new doors for future broodstock nutrition research.