Abstract The present study investigated the effects of varying protein source combinations and feeding strategies on the growth, health and organoleptic quality of the large yellow croaker ( Larimichthys crocea ). Three iso-nitrogenous and iso-lipidic diets were formulated. The control diet was made with 62% fish meal (FM). The other two experimental diets were formulated by replacing 45% FM with 22.5% mealworm (TM) and 22.5% cottonseed protein concentrate (CPC), or with 22.5% TM and 22.5% Clostridium autoethanogenum protein (CAP), respectively. The three kinds of diet were named as A1, A2 and A3, respectively. Five groups of large yellow croaker were fed with two different strategies: the first three groups were continuously fed with A1, A2 and A3 diets, respectively. The fourth group was alternately fed with A1 and A2 diet every 5 days. The fifth group was alternately fed with A1 and A3 diet every 5 days. The five groups were named D1, D2, D3, D1-2 and D1-3, respectively. Results showed that D2 and D3 groups exhibited significantly lower weight gain rate ( WGR ) and higher feed conversion ratios ( FCR ) compared to the D1 group. The D1-2 and D1-3 groups exhibited improved WGR and significantly reduced FCR compared to the D2 and D3 groups. The A2 and A3 diets significantly suppressed digestive enzymes’ activities compared to A1, whereas alternate-feeding groups significantly enhanced the enzyme activities. Compared to the D1 group, D2 and D3 groups significantly downregulated mRNA expression levels of intestinal anti-inflammatory cytokines and upregulated the expression of pro-inflammatory mediators. The anti-inflammatory abilities in the D1-2 and D1-3 groups were significantly higher than those in the D2 and D3 groups. Additionally, diets containing TM+CAP and TM+CPC protein sources enhanced ventral redness and yellowness indices. Considering the growth, digestion, immunity and organoleptic quality of large yellow croaker, it is recommended to replace up to 45% of FM with TM+CPC and use an alternate-feeding strategy.
Jiang et al. (Fri,) studied this question.