Maintenance and growth requirements for nitrogen, lysine and methionine and their utilisation efficiencies in juvenile black tiger shrimp, Penaeus monodon, using a factorial approach

Abstract

We used a factorial approach to distinguish maintenance from growth requirements for protein, lysine and methionine in the black tiger shrimp, Penaeus monodon. Juvenile P. monodon (initial weight 24g) were fed during 6 weeks one of ten semi-purified diets based on casein and purified amino acids (AA) as N source. The diets contained four levels of crude protein (CP, from 5 to 54% DM diet) with two levels (% CP) of lysine or methionine (normal or 30% deficient). Requirements were determined using linear and non-linear regression models. We could thus obtain the first ever data on maintenance (N equilibrium) requirements for CP and AA in P. monodon. CP requirements for maintenance (45g/kg body weight (BW) per d) represented approximately 19% of the CP requirement for maximal N gain (239g/kg BW per d). The marginal efficiency of utilisation reached a maximum of 38% for N, 077 for lysine and 162 for methionine using N gain as response. Lysine requirements were 020g/kg BW per d for N maintenance and 140g/kg BW per d for maximal N gain. Methionine requirements were 011g/kg BW per d for N maintenance and 070g/kg BW per d for maximal N gain. The lysine (58%) and methionine (29%) requirements for maximal N gain, expressed as percentage of protein requirement, agree with literature data using a dose-response technique with smaller P. monodon. The observed interaction between dietary CP and methionine for N gain demonstrates that requirements for indispensable AA (expressed as % CP) cannot be evaluated separately from CP requirements. Copyright © The Authors 2010.