Effect of genetic line, protein source, and protein level on growth, survival, and immune-related gene expression of Litopenaeus vannamei

Two shrimp genetic lines (LGR: faster growth and LWR: higher white spot syndrome virus resistance) were evaluated with six dietary treatments containing different sources (animal and plant), and three protein levels (low, medium and high). A five-week bioassay was conducted using Litopenaeus vannamei with an average initial weight of 2.08 +/- 0.06 g to determine the influence of the genetic line, protein source, and protein level on the weight gained per week, survival, and expression of immune-related genes. The overall mean of weight gain was 1.02 g/week for LGR and 0.71 g/week for LWR. Survival was 71.7% for LGR and 78.9% for LWR. The genetic line influenced weekly weight gain and survival while a significant interaction between genetic line, protein source, and protein level, influenced the expression of immune-related genes of shrimp. The data suggested that a diet containing plant-based protein (30-35%) at medium level was sufficient to obtain adequate values of weekly weight gain and survival without affecting the immune response. However, LGR showed higher weight gain, and LWR increased survival and gene expression levels related to the immune response. These results could be of interest on feed formulation for aquatic organisms and feeding strategies of farmed shrimp.