Morphological traits and growth performance of monosex male tilapia GIFT strain and Saint Peter®

This study aimed to compare the morphological traits and growth performance of monosex populations of the Genetic Improved Farmed Tilapia (GIFT) and Saint Peter (R) of male tilapias reared in a mixed system. The experiment was carried out from June 2012 to November 2012 in Sgarbi fish farm, Palotina, Parana State, Brazil. GIFT juveniles were obtained from the State University of Maringa (UEM/Codapar) fish farm broodstock, and the red hybrids were from the Sgarbi fish farm broodstock. The average genetic values of GIFT from three genetic groups (I, II, and III) were obtained by controlling individual pedigree and genetic evaluation using Best Linear Unbiased Prediction (BLUP). Information from complete GIFT pedigree since its introduction in Brazil was used, and the genetic groups were ranked as I (upper group), II (middle group), and III (inferior group). In all, 1,880 fish, including 480 GIFT strain and 1,400 red hybrids, with an average initial weight of 15 g, were placed in a semi-intensive system with a density of 4.7 fish m(-2). The fish were individually identified using Passive Integrated Transponder (PIT) tags. Harvesting was performed at the end of a 160 d period. The performance data including final weight and daily weight gain, and morphological traits including total length, standard length, body depth, head length, tail depth, tail width, body width, head length/standard length, body area and body volume were evaluated. Analysis of variance (ANOVA) and the Tukey test at 5% probability level were applied. The average final weight and daily weight gain among the three genetic groups of GIFT did not show significant differences. However all GIFT groups (I, II, and III) presented average values of performance and morphological traits higher that the Saint Peter (R). Among the GIFT genetic groups, only body depth between groups I and III showed significant differences (p<0.001). The morphological traits and growth performance are superior in the GIFT strain, regardless of its genetic group, when compared to Saint Peter (R), except for the head length/standard length ratio.