Effect of the protein–lipids ratio on growth and maturation of the crayfish Procambarus (Austrocambarus) llamasi Claudia Carmona-Osalde a,1 , Miguel Angel Olvera-Novoa a,1 , Miguel Rodrı ´guez-Serna b, * a Centro de Investigacio ´n y de Estudios Avanzados del IPN (CINVESTAV), Unidad Me ´rida, Laboratorio de Nutricio ´n, Departamento de Recursos del Mar, Antigua Carretera a Progreso Km. 6, A.P. 73 Cordemex, 97310 Me ´rida, Yucata ´n, Me ´xico b Universidad Nacional Auto ´noma de Me ´xico (UNAM), Facultad de Ciencias, Departamento de Biologı ´a, Ecologı ´a y Recursos Naturales, Unidad Multidisciplinaria de Docencia e Investigacio ´n, Sisal, Calle 19 s/n x Capitanı ´a de Puerto, Puerto de Sisal, Hunucma, Yucata ´n, Me ´xico Received 22 July 2004; received in revised form 26 April 2005; accepted 29 April 2005 Abstract The effect of six isocaloric diets with different protein (10%, 20% and 30%) and lipids (6% and 12%) contents was evaluated on growth and maturation of male and female juvenile P. llamasi crayfish. The experiment was carried out using individual plastic chambers within a closed, recirculating system with constant temperature. After 90 days, specific growth rate (SGR) values were generally low for both sexes. Lowest SGR for females was 0.4 with diet D1 (10/6) and highest was 0.7 with diet D4 (20/12). The lowest SGR for males was 0.3 with diet D1 (10/6) and the highest was 0.6 with diet D4 (20/12). Feed conversion ratio (FCR) varied from 1.1 to 1.8, and survival was generally high (N 80%) for both sexes. The Maturation Index (MI) behaved in a similar way to the Gonadosomatic Index (GI), manifesting a close relationship with dietary protein and lipids contents. Diet had a significant effect on maturation in females. The effect of protein and lipids content was significant with a direct relationship between these values and the MI and GI. Diets with the highest protein content had the best GI and MI values and all diets with 12% lipids had better MI and GI values than diets with 6%. Unlike the growth performance, the best maturation results were produced by the 30/12 diet. Based on the different observed effects of the diets on growth and maturation, it is recommended the use of a 20/12 diet for growth and a 30/12 diet for maturation. D 2005 Elsevier B.V. All rights reserved. 1. Introduction The interest in intensive and semi-intensive culture of some crayfish species have increased in recent decades. The production of supplementary feed in these systems is indispensable for reaching commer- cial sizes in the shortest time. Thus, a balanced feed that covers the requirements of these organisms is necessary. The nutritional requirements for some Parastacid and Cambarid species have been studied, with differ- ing results in many cases. Optimum growth has gen- erally been attained with diets containing between 0044-8486/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2005.04.071 * Corresponding author. Tel./fax: +52 988 912 0020x106. E-mail address: mrs@fciencias.unam.mx (M. Rodrı ´guez- Serna). 1 Tel.: +52 999 981 2903x297; fax: +52 999 981 2334. Aquaculture 250 (2005) 692 – 699 www.elsevier.com/locate/aqua-online