Effects of culturing systems in flesh quality, and an optimization of family contribution in gilthead sea bream (Sparus aurata, Linnaeus, 1758), under industrial conditions

Abstract

Gilthead sea bream is an important species in Spanish and European aquaculture, where breeding programs have been established. In Spain, PROGENSA®-III is the unique national project focused on genetic selection for fastgrowth and against deformity in this species, considering their relationships with carcass and flesh quality traits. An essential aspect of PROGENSA®-III is how the animals are related in order to increase the Estimation Breeding Value (EBV) and minimize the consanguinity level per generation. The present work is focused about flesh quality on different types of Spanish culturing systems (estuary, tank and oceanic cage), and how the management of breeders at industrial scale can improve the family contribution, and consequently the EBV for flesh quality traits. The results presented in this study, belong to the third generation of PROGENSA®, breeding the same families in estuary and tank (in Andalusia) and oceanic cage (in Canary Islands), which were slaughtered at harvest size (≈ 0.5 kg). Flesh quality was characterized by collagen, fat, moisture and protein content, by using FoodScanTMLab. Family contribution was quantified by studying two moments of the mass spawn (4th week [S1] and 7th week [S3]), using within each one four consecutive days as batch (4DL). For kinship, the specific SMsa1 multiplex was used, in order to establish the fish relationship in each batch. Allelic frequencies, Fst, Hardy-Weinberg equilibrium and the familiar contribution were estimated in each batch. Estuary and tank reported the highest values for muscle fat, protein and collagen, and the lowest value for moisture versus oceanic cage. Spite of culturing systems (estuary, tank and oceanic cage) present differences in terms of management, environment, diets, temperature, etc.., there were not different significantly for all these traits. Muscle fat measured by FFM reported lower variation than NIR approach. On the other hand, fish from oceanic cage reported higher values for growth traits (weight, length and condition factor) than estuary and tank. These results suggest the importance to use the culturing system as fixed factor in the genetic evaluation processes. Concerning genetic diversity markers, the mean observed heterozygosity for the whole population was 67.23%, while its value was 67.95% and 60.98% for S1 and S3 (batches), respectively. The mean number of alleles per locus was 7.45. The observed heterozygosity of this study was lower than values reported for wild populations (18.27%), and weakly lower than other industrial populations without selection program (7.01%), as expected. The Fst value between both batches was 0.0378, which is in concordance with values in other populations, according their origins.