Genetic parameters for productive traits and skin quality in Nile tilapia

Abstract

Tilapia skin has been considered an important biomaterial in the treatment of burns and tissue reconstruction in vaginoplasty. Improvements in tilapia skin quality are of great interest to regenerative medicine. This study aimed to (i) estimate variance components and genetic parameters for growth traits, fillet yield, and skin quality; (ii) assess genetic associations between productive traits and skin thickness; and (iii) investigate the effect of groups with high (HGM) and low (LGM) genetic merit for skin thickness on the expression of genes encoding the α2 and α3 chains of type I collagen in Nile tilapia (Oreochromis niloticus). Components of variance, heritability, and genetic correlations were estimated for skin thickness (ST, measured in millimeters), fillet yield (FY, measured in percentage), and weight at harvest (WH, measured in grams). The database contained records of 1221 mean values of three measurements for ST, 1213 measurements for FY, and 3171 measurements for WH. The sample included animals from the tenth generation of selection of the Nile tilapia breeding program of the State University of Maringá, Brazil. For analysis of gene expression, skin samples were collected from fish with LGM and HGM for ST. Heritability estimates were high for WH (0.71), intermediate for ST (0.59), and moderate for FY (0.21). The repeatability coefficient of ST was high (0.66). The genetic correlation between ST and WH was high and strong (0.77), whereas that between ST and FY was not significant (−0.02). There was a significant difference (p = 0.038) in COL1A3 expression between HGM (7.38 AU) and LGM (4.88 AU) groups. The results indicated that it is possible to increase the thickness and amount of type I collagen fibers in tilapia skin through selection. Genetic correlations indicated that selection for WT positively impacts ST without influencing FY. Selection for weight gain proved to be an effective tool for the production of Nile tilapia skins more suitable for use as xenografts.