Paulo de Paula Mendes

A multi-season survey for infectious myonecrosis in farmed shrimp, Litopenaeus vannamei, in Pernambuco, Brazil.

Infectious myonecrosis (IMN), caused by infectious myonecrosis virus (IMNV), is the disease of greatest impact on shrimp farming in the northeast region of Brazil. The occurrence of IMN remained restricted to northeastern Brazil until 2006, when its presence was also confirmed in Indonesia. To determine the occurrence and evolution of IMN in Litopenaeus vannamei farmed along the coast of the state of Pernambuco, Brazil, histopathological examinations were performed on 60 samples collected from four farms in both predominant seasons in the northeastern region: dry and wet seasons. Samples made up of ten specimens were collected monthly from each pond. Histopathological results were associated to wet-mount exams and rearing performance data. Lesions suggestive of IMN (coagulative necrosis, hemocytic infiltration in the musculature, ectopic spheroids in the lymphoid organ) were identified in all the farms, with a higher occurrence during the dry season. Longer rearing periods and higher stocking densities were the variables with the most significant influence (p<0.05) in the occurrence of IMN.

Influence of levels and forms of selenium associated with levels of vitamins C and E on the performance, yield and composition of tilapia fillet

The objective of this study was to evaluate the influence of vitamin C (VC), vitamin E (VE), and two selenium sources on the performance, yield, and composition of Nile tilapia fillet. The experiment was conducted in a completely randomized design consisting of six treatments with the addition of 100, 200, and 400 mg kg-1 VC and VE and 0.1, 0.2, and 0.4 of two sources of selenium. Each treatment had five replicates of 30 fish each. The diet with 200 mg kg-1 VC and VE + 0.2 mg.k-1 organic selenium resulted in weight gain, length gain, and feed conversion ratio similar to that of the treatment with 400 mg kg-1 VC and VE + 0.4 mg kg-1 organic or inorganic selenium. The addition of organic selenium to the diet improved the weight gain and feed conversion ratio in comparison with the addition of inorganic selenium. The diet with 0.2 mg kg-1 organic selenium showed glutathione peroxidase level equal to the diet with 0.4 mg kg-1 of inorganic selenium. Carcass and fillet yields were not affected by treatments; however, there was treatment effect on the fillets chemical composition.

AVALIAÇÃO DE POTENCIAL PROBIÓTICO FRENTE À INFECÇÃO EXPERIMENTAL POR VÍBRIOS EM PÓS-LARVAS DE CAMARÃO MARINHO

Bacillus spp. have been used against diseases caused by bacteria that affect cultured shrimp, providing beneficial effects on the host shrimps by altering their microbial community, and improving zootechnical indexes. The objective of this work was to evaluate the effects of a diet supplemented with Bacillus cereus—a bacterium with probiotic potential—on post-larvae Litopenaeus vannamei shrimps grown in laboratory. The experiment lasted for fifteen days and consisted of six treatments—control (T1), probiotic (T2), Vibrio parahaemolyticus (VP) (T3), probiotic and VP (T4), V. alginolyticus (VA) (T5), and probiotic and VA (T6). The survival rate, weight gain, colonization capacity of the probiotic bacteria, pathogen count, and histopathological lesions were evaluated. There was no significant difference (p≥0.05) in survival between treatments. The groups with pathogens and without probiotics presented lower weight gain. The result of the Bacillus cereus count in the treatments T2, T4 and T6 were significantly different (p<0.05), the probiotic bacteria were more aggressive in competing for space and nutrients when compared to V. parahaemolyticus than when compared to V. alginolyticus. Animals fed with the probiotic presented lower counts of these pathogens than those fed without the probiotic (p<0.05). No histopathological lesions were found in the organs and tissues of the shrimps. Bacillus cereus showed a high colonizing capacity in post-larvae shrimps, causing a significant reduction of pathogens, probably by secreting antimicrobial substances and the competitive exclusion, which justifies their use as probiotic bacteria.

CULTIVO DO CAMARÃO MARINHO, SOB DIFERENTES DENSIDADES DE ESTOCAGEM E ALIMENTAÇÃO, EM ÁGUAS OLIGOHALINAS

The cultivation of Litopenaeus vannamei has increased in inland areas by using low salinity waters. Cultivation techniques in coastal waters are well developed, however, studies for low salinity conditions are needed, especially regarding the ideal ionic composition of water and its effects on the zootechnical indices. Brazil has adopted this strategy and the semiarid region showed great potential due to its favorable climate and water conditions. Thus, experimental cultivations were conducted in Serra Talhada, State of Pernambuco, in order to evaluate the influence of two feeding strategies (with and without feeding) and three cultivation densities (5, 10 and 15 shrimps m), on the production variables of this species. Three ponds of 280 m were built, in which six nursery nets of 20 m were installed. The cultivation was performed with juvenile shrimps of 8.53 g and lasted 50 days. The animals were fed twice a day with commercial feed containing 25% of crude protein. The water quality (salinity ~1.0 g L, temperature ~28.09°C, pH ~8.48) and the shrimp growth were monitored with weekly biometry during the cultivation. A significant difference was found only in the treatment without feeding with 15 shrimps m, the average final weight of all treatments ranged from 13.16±1.33 g to 15.50±1.66 g. The survival rates were high in the treatments with feeding and its variation between treatments was 60.56±6.76% and 83.00±4.00%.

Desova induzida de curimatã-pacu submetido a dois protocolos de hipofisação

The objective of this work was to compare two hypophysation protocols in the spawning induction of curimata-pacu. The application of a single dose or two doses of crude carp pituitary extract was tested. That there was no significant difference among the protocols for the rate of females that have spawned, fertilization and deformed larvae. A single dose application resulted in higher degree-hour values until the oocyte extrusion than two doses. The application of a single dose represented a lower consumption of water, energy, and handling time. A single dose protocol can be used as an alternative for inducing the curimata-pacu spawning.