Effects of various levels of dietary copper supplementation with copper sulfate and copper hydroxychloride on Pacific white shrimp Litopenaeus vannamei performance and microbial communities

Abstract

A 42–day trial was conducted to evaluate the performance of juvenile (0.30g initial weight) Pacific white shrimp Litopenaeus vannamei offered diets containing various levels of copper hydroxychloride (Cu2(OH)3Cl) containing 58.8% copper (Cu) or Cu sulfate (CuSO4) containing 25.5% Cu. The basal diet (360g/kg protein, 80g/kg lipid) was primarily composed of soybean meal, fish meal, corn protein isolate and whole wheat and was formulated to be deficient in Cu (approximately 10mgCu/kg). The basal diet (B10) was supplemented with 30, 90, 150, and 210mgCu/kg from each Cu source. With the exception of 1 treatment (H220, Cu supplemented diet with dietary copper 210mg/kg from Cu hydroxychloride, n=4), five replicate groups of 15 shrimp per tank (initial weight 0.30g) were offered the test diets in slight excess. At the end of the trial, no significant differences were observed in final biomass (53.20–64.40g), final mean weight (4.34–4.87g), weight gain (1349–1544%), feed conversion ratio (FCR, 1.61–1.82), survival (81.3–96.0%), and thermal growth coefficient (0.082–0.087). The carapace, hepatopancreas, and whole shrimp Cu were significantly increased with dietary Cu levels from either source. No significant differences in hemolymph Cu contents were observed between the two sources. The Cu concentrations of hepatopancreas and whole shrimp were significantly lower in shrimp fed diets with Cu hydroxychloride than those in shrimp fed diets with Cu sulfate. The Cu contents of final whole body significantly increased with dietary Cu levels from either source and corresponded to a decreased trend in whole body Cu retention as dietary Cu increased regardless of source. Sequencing of intestinal and fecal microbiomes (16S V1–V3) captured distinct microbial communities based on source but not copper treatment group. However, the abundance of several specific family and genera of bacteria did appear to respond to different types and doses of dietary copper. Among these we observed a trend of decreased abundance of particular species of Vibrios, including V. harveyi, V. sinaloensis and V. orientalis. Results of this study confirm that both copper sources are utilized efficaciously by Pacific white shrimp, however, differential deposition patterns indicated the two sources of Cu are metabolized differently. Hence, additional studies to assess the specific metabolic pathways of various Cu sources as well as possible effects of high copper levels on resistance to infection should be undertaken in the future. Statement of relevanceIn this study, we assessed the efficacy of various levels of dietary copper supplementation with copper sulfate and copper hydroxychloride in Pacific white shrimp. Our finding shows that both copper sources are utilized efficaciously but metabolized differently by shrimp. This manuscript provides valuable information about effects of high copper levels from two copper sources in shrimp.