Does broodstock nutritional history affect the response of progeny to different first-feeding diets? A whole-body transcriptomic study of rainbow trout alevins

The whole-body transcriptome of trout alevins was characterized to investigate the effects of long-term feeding of rainbow trout broodstock females a diet free of fishmeal (FM) and fish oil (FO) on the metabolic capacities of progeny. Effects were studied before first feeding and after 3 weeks of feeding with diets containing different proportions of marine and plant ingredients. We showed that that maternal diet history did not significantly affect expression of any gene before the first feeding. We found an effect of maternal nutritional history on gene expression in alevins after 3 weeks of feeding. The major differences in the transcriptome of alevins from VEG-fed females compared to those from COM-fed females were: (i) a down-regulation of genes involved in muscle growth/contraction and (ii) a higher level of expression of genes involved in carbohydrate and energy metabolism related to the delay in growth/ development observed with plant-based diets. Our findings also showed an effect of the first-feeding diets, irrespective of maternal nutritional history. Specifically, the introduction of plant ingredients resulted in up-regulation of genes involved in AA/protein and cholesterol metabolism and in differences in the expression of genes related to carbohydrate metabolism. Transcriptomic response were studied in whole-body alevins from two broodstock groups collected before the first feeding (n=8/broodstock group) and after three weeks of feeding one of the three experimental diets (n=8/diet/broodstock group); COM = Broodstock commercial diet VEG = Broodstock totally plant-based diet (free of FM and FO) COM_M = Alevins from broodstock fed the COM diet, receiving a (FM-FO based) Marine diet for 3 wks COM_C = Alevins from broodstock fed the COM diet, receiving a commercial-like diet (mixed: plant-based and marine (FM&FO) ingredients) for 3 wks COM_V = Alevins from broodstock fed the COM diet, receiving a totally plant-based diet for 3 wks VEG_M = Alevins from broodstock fed the VEG diet, receiving a (FM-FO based) Marine diet for 3 wks VEG_C = Alevins from broodstock fed the VEG diet, receiving a commercial-like diet (mixed: plant-based and marine (FM&FO) ingredients) for 3 wks VEG_V = Alevins from broodstock fed the VEG diet, receiving a totally plant-based diet for 3 wks