Nutritional Utilization of Modified Carinata Brassica carinata Meals in Sunshine Bass Diets

Abstract

AbstractLow amounts (approximately ≤ 10%) of raw carinata Brassica carinata meals are used in animal diets due to the negative effects of antinutrients, mainly glucosinolates. We processed carinata meal by aerobic conversion followed with a single wash (ACCM). Another portion of carinata meal was double‐washed without aerobic conversion (WCM). The objective of this study was to determine if sunshine bass (female White Bass Morone chrysops × male Striped Bass M. saxatilis) fed diets containing low (20%) animal meals could tolerate up to 30% of ACCM or 30% of WCM. Twenty randomly selected sunshine bass (19.2 ± 0.08 g) were stocked in each tank (106 L) of a 32‐tank recirculating aquaculture system, with temperature maintained at 25.6 ± 0.7°C using an inline heater. Seven and six replicates were used for the reference and test diets (10% or 30% ACCM or 30% WCM), respectively, and the fish were cultured for 106 d. Growth improved with increasing levels of processed carinata meals in diets. Survival (>99%) was similar among dietary treatments. Consumption of 30% ACCM and 30% WCM diets was higher than for the reference diet. Feed conversion ratio improved in the WCM dietary treatment and was associated with a better protein efficiency ratio and apparent net protein utilization. Protein deposition was highest in sunshine bass fed 30% of processed carinata meals. Whole‐body protein also increased with increasing processed carinata meals in diets. Sunshine bass fed 30% WCM had lower liver weights and were in better condition than sunshine bass fed other diets. Hematocrit was high in sunshine bass fed ACCM diets. Although carinata meal is high in iron, the single wash in ACCM processing likely removed less iron than the two washes in WCM processing. Hemoglobin contents of sunshine bass were also increased by ACCM but not by WCM. Our results demonstrate that high levels of even moderately processed carinata meal (WCM) can be tolerated in fish diets without affecting fish performance.