Reduction of Particle Size of Rhizoclonium riparium Protein Concentrate Improves Digestibility, Growth, and Feed Efficiency of Penaeus vannamei Post Larvae

The present study evaluated the effect of particle size (PS) of Rhizoclonium protein concentrate (RPC) on apparent digestibility coefficients (ADC) as well as on growth and feed efficiency of Pacific white shrimp (Penaeus vannamei) for a period of 30 days. Results showed that white shrimp could effectively digest Rhizoclonium protein concentrate in their diet. Average ADC values for dry matter (ADMD), crude protein (ADCP), and crude lipid (ADCL) were 71.1%, 84.4%, and 94.6%, respectively. A significant inverse relationship (p<0.05) was estimated between PS and ADMD (r=-0.66, p= 0.02). Particle size of 150 µm resulted in the highest final body weight (FBW), weight gain (WG), specific growth rate (SGR), feed conversion efficiency (FCE) and protein efficiency ratio (PER). All response parameters exhibited significant inverse correlations with particle size (p<0.05). In conclusion, digestibility of seaweed protein concentrate and its nutritive value could be improved by grinding it to an optimum size of 150 µm before dietary inclusion.