Dietary effects of Enteromorpha prolifera on growth performance and flesh quality of Litopenaeus vannamei

This trial was conducted to evaluate the effects of dietary Enteromorpha prolifera ( EP ) with different fishmeal inclusion on growth and flesh quality of Pacific white shrimp (Litopenaeus vannamei). This trial was designed with 2×3 factors, and two basal diets were designed to contain 18% (A) and 15% (B) fishmeal. Then the EP was added in both basal diets at the levels of 0, 3%, 6% to form six isonitrogenous and isoenergetic diets with crude protein content of 38.5%, referred to as A0, A3, A6, and B0, B3, B6, respectively. A total of 6 treatments was conducted with 4 replicates per treatment and 50 L. vannamei per replicate. After 8 weeks of feeding, the growth performance, body composition, nutrient utilization, flesh water-holding capacity and texture property of the L. vannamei were measured. The results showed that both fishmeal and EP levels in diets significantly affected the final body weight, weight gain rate (WGR) and feed conversion ratio (FCR) of shrimp. The A0 group had a final weight of 22.6 g with the highest WGR (654.2%) and the lowest FCR (1.61), while the B6 group had a final weight of 20.8 g with the lowest WGR (595.7%) and the highest FCR (1.81) among the six groups. The supplementation of 3% EP in both basal diets did not significantly affect the growth performance, while the supplementation of 6% EP significantly decreased the WGR, increased the FCR. At the same supplementation level of EP, the WGR of 15% fishmeal groups (B groups) was numerically lower than that of 18% fishmeal groups (A groups). The EP level significantly affected the crude protein and crude lipid content of whole shrimp. The crude protein content of A6, B0, B3 and B6 groups was significantly lower than that of A0 group, and the crude fat content of A6 and B6 groups was significantly lower than that of A0 and B0 groups. The fishmeal and EP levels in diets significantly affected the protein efficiency ratio (PER) and protein retention efficiency (PRE), and the EP level also significantly affected the lipid retention efficiency (LRE) and apparent digestibility coefficient of crude protein (ADCCP). The PER, PRE, LRE and ADDCP of A3, A6 and B3, B6 groups were significantly lower than those of A0 and B0 groups respectively. In terms of flesh quality, the supplementation of 6% EP significantly reduced the cooking loss and thawing loss, and increased the flesh collagen content. The flesh hardness and chewiness of A3, A6 and B6 groups were also significantly higher than those of A0 and B0 groups, respectively. In conclusion, the supplementation of 3% EP in diet did not significantly affect the growth of L. vannamei, and 6% EP supplementation improved the flesh quality, although this supplementation reduced the weight gain and feed utilization.