Growth and feed intake of Litopenaeous vannemei under stress-environment interaction

Abstract:

In this study, sub-chronic toxicological experiments were carried out on the growth and feeding of Litopenaeus vannamei by three groups of two environment factors, including ammonia-nitrogen (0, 5, 10 mg/L) with nitrite-nitrogen (0, 5, 10 mg/L), nitrite-N (0, 5, 10 mg/L) with salinities (5, 15, 25), and ammonia-N (0, 5, 10 mg/L) with pH (7.6, 8.2, 8.8). After 7 days of continuous culture, the growth and feed intake parameters all decreased with nitrite-N and ammonia-N concentration (P<0.05). Compared with control treatment, the specific growth rate, feed intake and feed conversion rate decreased by 18.31%, 14.68% and 17.49% at highest concentration of ammonia-N and nitrite-N, respectively. In the culture with ammonia-N as exclusive N source addition, the parameters of pH 7.6 and pH 8.8 were significantly lower than those of pH 7.6 (P<0.05). Furthermore, the survival rate of pH 8.8 was lower than those of pH 7.6 and pH 8.2 (P<0.05), and all individuals died on the second day in the pH 8.8 and 10 mg/L ammonia-N treatment, suggesting that high pH value would enhance the negative effects induced by ammonia-N to L. vannamei. In the culture with nitrite-N as exclusive N source addition, the salinity had no influence on feed intake (P>0.05), but had significant effects on the specific growth rate and feed conversion (P<0.05). When concentration of nitrite-N reached 10 mg/L, the specific growth rate, feed conversion and survival rate of both salinity 15 and salinity 25 were higher than those of salinity 5 (P<0.05). The result showed that high salinity could alleviate the inhibition of nitrite-N on growth, while high pH value would exacerbate the toxicity of ammonia-N to L. vannamei.