Characterization of wastewater generated byLitopenaeus vannameiafter being fed experimental diets based on animal protein, vegetable protein and a commercial diet

Phosphorous (P) and nitrogen (N) residuals from Litopenaeus vannamei and N and P retention by L. vannamei were studied at three protein levels and with two protein sources: fish meal with plant protein (AVD) and plant protein with squid meal as an attractant (VD). A protein retention bioassay began with shrimp that were 1.5–2.5 g, and nutrient release bioassays were conducted with shrimp of two sizes (4.5 and 8.5 g). Both bioassays were conducted at: 30 ± 0.5°C, [O2] > 4 mg L−1, and 38 UPS. Total P residuals were significantly higher for AVDs than for VDs (P < 0.05), particularly those with a high dietary protein level. The particulate P fraction was the predominant form of P. Total N and inorganic dissolved N, mainly in ammonia form, significantly increased (P < 0.05) with dietary protein level and shrimp size, regardless of the protein source. VDs resulted in significantly greater P retention (P < 0.05) than AVDs, without significantly affecting growth rates or survival. P retention as well as N retention decreased with increasing protein supplementation level, independently of the protein source used (P > 0.05). This study shows that the substitution of fish meal with plant protein (soybean meal and wheat flour) improves P retention in L. vannamei.