This study aimed to evaluate the probiotic additive on tilapia growth by establishing growth curves, as well as assessing the morphology of the muscular and ventral subcutaneous adipose tissues, carcass characteristics and gene expression that controls growth. Fingerlings of 5 g were grown in a recirculating aquaculture system consisting of 15 water tanks (0.25 m3) at 80 fish/m3. Fish were fed three times daily with the same feed, using additive with Bacillus subtilis, Bifidobacterium bifidum, Enterococcus faecium, Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus lactis, Lactobacillus plantarum and Pediococcus acidilactici (1.0 × 109 CFU/g). They were assessed levels of 0.1% and 0.2% of additive probiotic homogenized in 2% soy oil and sprinkled over the feed. Exponential models were fit to compare growth rates, weighing samples at days 0, 30, 60 and 90 of cultivation. The probiotic mixture used in this study as feed additive may be diffused in aquaculture in order to increase productivity, as demonstrated by feed conversion rate, final weight and growth (13%–37% for 0.1% and 0.2% of additive level respectively). Growth stimulation occurred by white muscle fibre hypertrophy, accompanied by inhibition of MyoD and myostatin, gene expression and increase in the number of intestinal villi, ensuring greater absorption and utilization of nutrients provided in the diet.

The aim of this study was to evaluate the performance of three Nile tilapia strains in Brazil compared to Genomar Supreme™ Generation 24 from the Philippines. Tilapia fingerlings, male population, of approximately 8 g which were cultivated in water recirculation systems containing 0.5 m 3 tanks, density of 60 fish m −3 , with four replicates (tanks). The fish will be fed three times a day with the same commercial feed for each particular growth phase according to biomass in each tank. Five fish from each tank were sampled at the start and 60th, 120th, 180th and 240th days of cultivation. They were determined the weight gain, feed conversion and homogeneity of batch in each period. The Gompertz model given by y = Ae (−Be −Kx) was fit and it was calculated the absolute and relative growth rate. The weight and age at inflection point were calculated too. The improvement programme from Genomar in the Philippines brings tilapia strain with better growth rate and performance when compared with the one commercialized in Brazil. This Philippine strain constitutes an important potential to improve tilapia farm in Brazil. However, the use of this genetics needs to be accomplished in this country.

This study aimed to evaluate the growth and performance of genetically improved tilapia reared at different temperatures. Four hundred and eighty fingerlings of Genomar Supreme Tilapia, GST (8.39 ± 0.60 g) were equally separated into three indoor water recirculation systems maintained at 22, 26 and 30 ºC. Each of four tanks contained 500 liters with 40 fish per tank in natural photoperiod. The fish were fed ad libitum with the same feed for each growth phase, weighing the total feed supplied. After 30 min of feeding, leftover feed was collected, dried in an oven and weighed. Ten fish from each tank were weighed at days 1, 30, 60, 90, 120, 150, 180 and 210. Survival, weight gain, feed conversion and feed intake in each period were determined. Fish reared at 30 ºC and 26 ºC showed a higher specific growth rate than that of fish reared at 22ºC (P≤0.05). Feed intake increased along temperature and feed conversion and was poorest in fish reared at 26ºC (P≤0.05). Final fish weight estimates at day 210 by the Gompertz model were 597.84, 819.26 and 1079.39 g for 22, 26 and 30 ºC, respectively. At 30 ºC, fish had a higher absolute growth rate (7.76 g day−1) and lower weight (459.30 g) and age (95.85 days) at the inflection point. Tilapia at 22 ºC had a higher weight (539.57 g) and age (197 days) and lower absolute growth rate (4.52 g day−1). It was concluded that GST tilapia can potentially improve aquaculture in all Brazilian regions based on different rearing temperatures.

The growth of generations of the Genomar Supreme Tilapia (GST) strain, specifically G20 and G25, was evaluated. Tilapias 8 g were reared in a recirculating aquaculture system with 0.25 m³ tanks, 80 fish m-³, with four replicates. During growth, eight fish from each tank were weighed and measured at day 1, 30, 60, 90, 120, 150, 180 and 210. Survival, weight gain, feed conversion and batch homogeneity were determined. Weight-age data were fit to Gompertz model. In addition, absolute and relative growth rates and weight and age at inflection were determined. Final weight showed 26.7% higher in G25 when compared to G20 (920.05 and 725.87 g, respectively). The feed conversion and homogeneity indexes were better in G25 than G20. The estimate of asymptotic weight was higher in G25 (1202.0 g) when compared to G20 (912.7 g). G20 presented smaller weight (335.76 g), age (108.87 days) and absolute growth rate (4.87 g day-1) when compared with G25 (442.19 g, 113.77 days and 6.41 g day-1). Carcass characteristics were similar, but G25 presented about 25% higher fillet weight than G20. After five years in the GST breeding program, results indicated that a sustained improvement of harvest weight was achieved, as well as 6 to 10% gain in performance by generation.