There have been promising results associated with broodstock (BS) programming, in which BS fish exposed to an unfavorable feed component can pass epigenetically induced adaptation to the same feed components to their offspring. The objective of this study was to investigate the effect of nutritional programming of BS using live feed enriched with SBM on 1) spawning quality 2) growth performance, survival, and 3) gut health of the offspring fed SBM-based diet.
Zebrafish, Danio rerio, was used as the model species. BS were fed (nutritionally programmed) for two weeks with non-enriched (C) or SBM enriched (P) Artemia nauplii and subsequently spawned. This process was repeated on 3 separate sets of BS to examine fertilization and hatching rates in both groups. Fish larvae from each group were initially raised in separate BS group common gardens, until 21 days post hatch (dph). Fish were randomly stocked into 4.5L tanks with 32 fish per tank. Each tank was randomly assigned 1 of 4 treatments in triplicate: offspring fish from C-BS fed with either fishmeal (FM)-based (CFM) or soybean meal (SBM)-based diets (CSBM), and offspring fish from P-BS fed with either FM-based (PFM) or SBM-based diets (PSBM). Fish were fed at a restricted rate for four weeks; this was calculated weekly according to lowest tank feed intake.
No significant differences were detected in BS fertilization and hatch rates for any of the three spawns post-programming. At 49dph, there was no significant interaction between BS type and diet on average final weights and feed conversion ratio (FCR). However, there was a significant effect of diet, SBM diet groups had lower final weights and higher FCR compared to FM diet groups (p<0.05). There was a significant difference in distal intestinal villi ratios with programmed groups having smaller ratios than control (p<0.05), possibly indicating lower nutrient absorption ability. No significant interaction of BS and diet was detected. Intestinal gene expression of il1B was elevated in CSBM compared to all groups. The expression of tnfα and Il10 in CSBM and PFM groups were elevated compared to the control (CFM). Finally, mmp9 expression was elevated in PFM compared to CFM. There was no significant difference in survival between groups.
The study found that nutritional programming using live food enriched with SBM does not have any negative effects on the quality of spawning. However, while broodstock programming did not improve growth performance of offspring fed SBM diets the reduced gut inflammation in those fish may be indicative of some adaptation gained to this inflammatory plant-based diet.