Dietary Supplementation with Fumaric Acid Improves Growth Performance in Nile Tilapia Juveniles.

Organic acids have recently been identified as promising replacements for antibiotics in aquafeeds that promote fish growth and feed efficiency. This study evaluated the inclusion of fumaric acid (FA; 0, 5, 10, 15, 20, and 30 g/kg) in diets (350 g/kg CP; 3.4 kcal digestible energy/g) of Nile tilapia juveniles. Fish (average weight 1.7 ± 0.1 g) were distributed in three 40 L aquaria per treatment (13 fish/aquaria) in a completely randomized design. Over 35 days, the fish received the experimental diets three times daily to apparent satiety. The maximum weight gain, feed efficiency ratio, and protein efficiency ratio were recorded in fish supplemented with 14-15 g/kg FA. After 28 days, Enterobacteriaceae was registered only in the gut of tilapia without FA augmentation. Gram-negative bacteria in the fish gut decreased (p < 0.05) in fish receiving 17 g/kg of dietary FA, increased after this level. The intestinal villi height and width were affected (p < 0.05) by FA levels and feeding time. Thus, inclusion of 15 g/kg of FA was effective in promoting growth, improving intestinal morphometry, and decreasing negative gut bacteria of Nile tilapia juveniles after 35 days.

Effect of dietary crude glycerin on the productive performance of Nile tilapia fingerlings.

The aim of this study was to evaluate the effect of different crude glycerin levels in the diet of Nile tilapia fingerlings (mean initial weight 0.32 ± 0.06 g, n = 450) on growth performance parameters, whole-body composition, blood glucose and liver morphology. Crude glycerin was tested at six different levels (0, 4, 8, 12, 16, and 20%) in diets containing 30% digestible protein and 3,000 kcal kg-1 digestible energy. After 37 days of feeding, the inclusion of crude glycerin resulted in positive effects on final weight, visceral fat, weight gain, feed conversion, specific growth rate and feed intake. The different treatments did not influence fillet yield, glycemia, survival and hepatosomatic index, but intermediate levels of inclusion decreased the area of hepatocytes. Regarding fish body composition, significant differences were found in moisture and ash contents, with no changes in crude protein and total lipid. The inclusion of crude glycerin in the Nile tilapia diet improves growth performance without negatively affecting survival rate and glycemia of fingerlings.

Alcoholic extract of propolis in Nile tilapia post-larvae and fingerlings' diets: effects on production performance, body composition and intestinal histology.

The aim of this study was to evaluate the production performance of Nile tilapia post-larvae and fingerlings fed with increasing levels of alcoholic extract of propolis into diets. In Experiment 1, 1800 post-larvae were distributed in 30 tanks, in a completely randomized design with five treatments composed by the inclusion of 0, 1, 2, 3 and 4 g of dry propolis/kg of feed, and six replicates. In experiment 2, 1600 fingerlings were distributed in the same system and designed as experiment 1. No significant effect was observed between treatments, for final weight, total and standard length, survival, and intestinal villus height. However, the propolis extract inclusion of 1 g/kg in Nile tilapia post-larvae and fingerlings' feed resulted in a better body condition factor and higher body protein deposition (p<0.05). The condition factor is an estimate for the future growth of the animals, possibly the fish treated with propolis extract will present better growth, survival and greater reproductive potential rates. The results of the present study demonstrate that alcoholic extract of propolis improves the nutritional condition of Nile tilapia post-larvae and fingerlings, potentially leading to increased productivity in subsequent stages, as well as leading to improvement in fingerlings muscle deposition.

Níveis de proteína e fitase em rações de terminação para a tilápia do Nilo (Oreocrhomis niloticus) / Protein and Phytase Levels on Finishing Rations to Nile Tilapia (Oreochromis Niloticus) / Niveles de proteína fitasa en racines para la tilapia del nilo (Oreochromis niloticos), en terminación

Este trabalho foi realizado para avaliar rações com dois níveis de proteína bruta (PB) sem e com suplementação de fitase, sobre o desempenho da tilápia do Nilo na terminação, e teve duração de 74 dias. Foram utilizados 60 peixes com peso vivo inicial de 274,39 + ou - 13,50 g, distribuídos em um delineamento em esquema fatorial 2 x 2, com dois níveis de fitase [0 e 500 UF (unidades de fitase)/kg de ração] e dois níveis de PB (25 e 28) em 12 tanques com volume unitário útil de 800 L. Os melhores resultados de ganho de peso, conversão alimentar e taxa de eficiência protéica, rendimento de carcaça, sobrevivência, cálcio e fósforo (P) nos ossos e para os coeficientes de digestibilidade aparente da PB e do P, foram obtidos com a ração contendo 28 PB suplementada com fitase. A suplementação de fitase, independentemente do nível de PB da ração, reduziu a excreção de nitrogênio e P pelos peixes. Concluiu-se que para a tilápia do Nilo na terminação, a ração com 28 de PB suplementada com fitase proporciona os melhores resultados.