Effects of ambient colour on colour preference and growth of juvenile rainbow trout Oncorhynchus mykiss (Walbaum)

Colour preference of individual juvenile rainbow trout Oncorhynchus mykiss was tested at 1 and 12 degrees C, and also at 12 degrees C after a 42 day growth experiment under white, blue, green, yellow or red ambient colour. All experiments were carried out under controlled laboratory conditions and the preference was assessed by the location of the fish in a preference tank with four chambers. Rainbow trout showed a preference for blue and green at 1 degrees C and for green at 12 degrees C. After the growth experiment the fish reared in blue tanks preferred blue and green but green was the most preferred colour for the fish reared in green, yellow and red tanks. Yellow and especially red chambers were avoided, irrespective of the ambient colour during the growth trial. The final mass of fish reared in the red aquaria was significantly smaller than that of the fish in green tanks. In addition, when the data of the preference tests were correlated with the data of the growth experiment using mean values of the four tested colours, a very good linear relationship was observed between the preference (i.e. visit frequency in coloured compartments) and growth rate as well as food intake. When considering the results both from the preference and growth trials it is suggested that green is the best environmental colour for rearing juvenile rainbow trout while rearing in a red environment cannot be recommended. (c) 2008 The Authors Journal compilation (c) 2008 The Fisheries Society of the British Isles.

A Via Campesina Brasil e a avaliação da primeira década de impactos da reforma agrária do Banco Mundial

During the past decade, influenced strongly by World Bank land policies, many governments instituted a new mode of recreating the peasantry, one supposedly led by market forces through credit programs secured by land. Supported by large landowner organizations, defended as a conquest by the rural labor movement and combated by member organizations of the Via Campesina, the new mode of peasant renovation has inspired a diversity of interpretations both positive and negative. To evaluate these events, this article seeks to demonstrate the World Bank's intentionality in urging the implementation of market-led agrarian reform in developing countries; discusses the construction of immaterial territories in the context of this policy; analyzes the development of a people's think tank in response to the agitation of the Via Campesina Brazil and the negative impact of the credit system on peasants.

Benefits of using the probiotic Efinol((R))L during transportation of cardinal tetra, Paracheirodon axelrodi (Schultz), in the Amazon

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relação lisina digestível: proteína digestível em rações para tilápias-do-nilo

This study was carried out to determine the best digestible protein/digestible lysine ratio that should be present in feed fed to Nile tilapias. Two hundred and sixteen tilapias (11.0 +/- 0.43g) were distributed in 36 fish tanks (205 L) at a density of 6 fish/tank. Twelve feeds were formulated with three different digestible protein (DP) levels 22.0; 26.0 and 30.0% (based on digestible amino acids) and four different lysine percentages of 4.5; 6.0; 7.5 or 9.0% in relation to digestible protein. The fish were fed ad libtum during a 60-day period. There was significant effect of the digestible protein and digestible lysine ratio on weight gain, because the increase in lysine levels in feeds with 26 and 30% DP promoted linear increase in this parameter. The best values for feed conversion were obtained at the levels 26 and 30% DP that increased the daily consumption of digestible protein. The lysine level caused a linear reduction in feed conversion and linear increase in the protein efficiency rate. The results suggested that the 26% DP level might be used in ration to feed Nile tilapia juveniles; however, these should contain digestible amino acids and the digestible lysine/digestible protein ratio should be 6.0%. However, for levels higher than 26% DP, a maximum digestible lysine level of 7.5% DP improved weight gain for the species.

Níveis de proteína digestível e energia digestível em dietas para tilápias-do-nilo formuladas com base no conceito de proteína ideal

This study was carried out to determine the best digestible energy and digestible protein ratio in feeds for Nile tilapia (Oreochromis niloticus) juveniles 30.0 +/- 4.21 g) based on digestible amino acids and the ideal protein concept). Twelve rations were formulated with protein levels 22.0; 26.0; 30.0 and 34.0% of digestible protein and levels 3,000, 3,300 and 3,600 kcal/kg digestible energy. The digestible energy/digestible protein ratio was between 8.94 and 15.19 kcal/g. Three hundred and twenty four tilapias were randomly distributed in thirty six 250 L circular tanks at a density of 9 fish/tank, a total of 12 treatments with three replications. After 60 days, there was no significant difference in weight gain, daily weight gain and feed conversion ratio among the studied treatments. A linear increase was observed in fillet yield with increasing digestible protein. With respect to feed cost/kg weight gain, the treatment with 30.0% DP and 3,000 kcal/kg DE presented low cost and better cost effectiveness index. Therefore, it was concluded that digestible energy did not influence the productive performance parameters and that effective feeds can be formulated with DP levels lower than 34% when feeding juvenile tilapias. The ration should be formulated based on the concept of ideal protein.

Hematologia e sinais clínicos de Piaractus mesopotamicus infectados experimentalmente com Aeromonas hydrophila

The purpose of this study was to evaluate the hematological response and clinical sign of Piaractus mesopotamicus infected by Aeromonas hydrophila. Were used 324 pacus, P. mesopotamicus weighing 102.84 [plus or minus] 27.1 g distributed in 27 water tanks with 300 L of capacity, 14 fish per tank. The fish were kept in the water tanks during one month, receiving appropriate diet. In this period was avoided stressing management. After this period, the fish were infected with 6 X 108 cfu of A. hydrophila fish-1, injected intraperitoneally. The blood collection was carried 24th before experimental infection and 2411 after its. The A. hydrophila infection in P. mesopotamicus is characterized by dark skin and clinical signs related to hemorrhage, hypochromic normocytic anemia, decrease on plasmatic proteins and globulins levels, leucopenia, lymphopenia, thrombocytopenia, eosinophilia, neutrophilia and monocytosis.

Selênio orgânico na alimentação de matrizes de tilápia-do-Nilo (Oreochromis niloticus)

Organic selenium in the diet of Nile tilapia (Oreochromis niloticus) broodstock. The aim of this study to test the effect of organic selenium supplementation in the diets of Nile tilapia broodstock. Growth, reproductive performance and performance of fingerlings were evaluated. Eighty adult fish were used, with average weight of 121.7 g and divided into groups of four animals (3 female and 1 male) stocked in 20 tanks with 1.5 cubic meters. The fish were fed five diets containing different levels of organic selenium (0.0, 0.25, 0.50, 0.75, and 1.0 mg kg-1 ration). In the experimental period, females from all tanks were captured and the eggs collected. The experimental design was entirely randomized, with five treatments and four replicates. To evaluate progeny performance, the fingerlings were shared in four aquariums and fed during 30 days with commercial diet (45% CP). The supplementation with organic selenium did not affect the productive performance as with the reproductive parameters of the broodstock (p > 0.05). on the other hand, the broodstock fed with 0.50 mg of organic selenium produced fingerlings that presented improved weight gain (p < 0.05) compared to fish fed the control diet.

Desempenho produtivo de tilápia do Nilo alimentada com níveis de colina na dieta

Growth performance of Nile tilapia fed graded choline levels in the diet. A 109-day feeding trial was undertaken aiming to evaluate the growth performance of Nile tilapia fed graded choline levels One hundred and ninety-two (initial-weight 4 0 [plus or minus] 0 15 g) fingerlings were distributed into 32 net cages (200 L each), four cages per treatment and six fish per cage, placed in eight 10001, aquaria in a closed recirculation system The treatments were assigned to the tanks comprising eight treatments and loin replications arranged in a completely randomized experimental design Diets were supplemented with choline chloride to provide 100, 200, 400, 600, 800, 1000, 1200 mg of choline per kg of feed and an unsupplemented diet No significant differences were observed in growth performance, survival, apparent feed conversion, liver and fillet ether extract, hepatosomatic index and plasma lipid concentration, among treatments Choline levels did not improve growth performance, possibly because the amount of choline in the diet had already met fish requirement

Effects of stocking density on growth of channel catfish, Ictalurus punctatus, fingerlings in Southern Brazil

Channel catfish, Ictalurus punctatus, fingerlings (mean length: 4.0±0.5 cm) were stocked into sixteen 16-m2 tanks with cement walls and earth bottoms. Four stocking densities were used: 10, 15, 20, and 25 fish/m2. Fish were fed a prepared diet containing 36% protein according to a fish size/water temperature-dependant chart for 120 days. Fish were stocked on January 20, 1992. Average water temperature varied from 19.7°C to 28.5°C. Final mean values of individual fish length and weight were significantly higher (P < 0.05) for the density of 10 fish/m2 and averaged 19.4±2.6 cm and 70.0±16.9 g, respectively. Food conversion ratio was significantly higher (P < 0.05) for fish stocked at rate of 25 fish/m2. Survival rates averaged 91.4%, with no significant differences (P > 0.05) found among treatments. These results demonstrate the viability of channel catfish fingerling growth in southern Brazil.

Growth of Channel Catfish, Ictalurus punctatus, in Southern Brazil

Despite successful introduction of channel catfish into Brazil in 1980, no studies have been conducted to assess the performance of channel catfish, Ictalurus punctatus, farming in southern Brazil. Fingerlings (27.0 ± 2.2 g) were stocked in sixteen 16-m2 tanks with cement walls and earthen bottoms. Four stocking densities were used: 0.5, 0.75, 1.0, and 1.25 fish/m2. Fish were fed a diet containing 32% protein according to a feeding chart for 257 days (from April to December). Water temperature ranged from 16.4°C to 30°C during the study. Final average weight (727.1 ± 70.6 g) was significantly higher (P < 0.05) for fish raised at 0.5 fish/m2. Food conversion ratio (FCR) was significantly higher (P < 0.05) for fish stocked at 1.25 fish/ m2. Survival averaged 95.4%, and no significant differences (P > 0.05) were found among treatments. There was no significant difference (P > 0.05) in tank production among the densities of 0.75, 1.0, and 1.25 fish/m2, but they were higher (P < 0.05) than the density of 0.5 fish/ m2. These results demonstrate the viability of channel catfish growth in southern Brazil.

Acid and fermented silage characterization and determination of apparent digestibility coefficient of crude protein for pacu Piaractus mesopotamicus

Three types of raw materials including commercial waste from saltwater (SW), freshwater fish (FW) and tilapia fillet residue (FR) were used to produce fish silage by either acid digestion (2% formic acid and 2% sulfuric acid) or anaerobic fermentation (5% of Lactobacillus plantarum and 15% sugar cane molasses). Six test diets were used in digestibility trials prepared with 70% reference diet and 30% of each experimental silage. These diets were fed to juvenile pacu Piaractus mesopotamicus (146 g average weight) in triplicate. Fish were kept in 500-L tanks and feces collected by manual extrusion. It was observed for both processes that SW waste always had the highest moisture content and lowest fat and ash. Highest crude protein levels were found in silages from commercial fish waste (SW and FW) made from whole fish unfit for human consumption. However, apparent digestibility coefficients did not vary among diets (P > 0.05). Although values did not differ statistically, fermented silage consistently displayed higher digestibility coefficients compared to acid silage. The silages exhibited relatively high protein digestibility (72.5-80.0%), thus suggesting the feasibility of using fish industry by-products in aquaculture feeds.

Effect of fish density during transportation on stress and mortality of juvenile Tambaqui Colossoma macropomum

The increased demand for juvenile tambaqui Colossoma macropomum for grow-out ponds and stocking programs in the Amazon state of Brazil has increased the transportation of this species. This study was designed to determine the optimum density of juvenile tambaqui during transportation in closed containers. Fish (51.9 ± 3.3 g and 14.9 ± 0.4 cm) were packed in sealed plastic bags and transported for 10 h at four densities: 78, 156, 234, and 312 kg/m3. After transportation, fish from each density were kept in separate 500-L tanks for 96 h. Mortality, 96-h cumulative mortality, water quality, and blood parameters (hematocrit, plasma cortisol, and glucose) were monitored. Fish mortality after transportation was significantly lower at densities of 78 and 156 kg/m3 than at 234 and 312 kg/m3. Cumulative mortality was significantly lower at a density of 78 kg/m3. Dissolved oxygen after 10 h of transportation remained high at a density of 78 kg/m3, but reached critically low values at all other densities. Ammonia concentration was highest at the lowest density and was lower at higher densities. Carbon dioxide concentration was lowest at the density of 78 kg/m3 but higher in the other treatments. Plasma glucose and cortisol increased significantly immediately after transportation at densities of 156, 234, and 312 kg/m3, returning to control values by 24 h. The best density for juvenile tambaqui during a 10-h transportation haul in a closed container was 78 kg/m3. At this density there was no fish mortality, water quality was kept within acceptable values, and fish were not stressed.

Monitoramento sanitário de um sistema integrado de tratamento de águas residuárias da suinocultura

Objective. To assess the potential for contamination of wastewaters from pig farming. Methods. Wastewaters from pig farming were stored in a tank. After 0, 30, 60, 90, and 120 days of hydraulic retention, they were added to lysimeters filled with argillaceous, sandy, or medium soil. Finally, these lysimeters were submitted to simulations of either a rainy season or a dry season. The number of colony-forming units (CFUs) of total coliforms, fecal coliforms, and fecal streptococci was measured in the effluents of the storage tank (for the various periods of hydraulic retention), in the percolate from the lysimeters, and in the three types of soil. The microbiological analyses were carried out using the membrane filter technique. The pH analyses were done potentiometrically. Results. For the three microorganisms, the largest decrease in bacterial counts in the storage tanks occurred with 90 or 120 days of retention. There was a marked decrease in the bacterial count in the percolates of the three soils. For the three soil types the greatest reduction in bacterial counts was found in medium soil, due to its acidity (pH < 7.0). Hydraulic retention was not sufficient to ensure the sanitary adequacy of the wastewaters and their use for irrigation, given that fecal coliform values were above 1 000 CFU per 100 mL. Therefore, adding the residues to the soil was considered a second stage of treatment. Conclusions. The retention of wastewaters followed by adding them to soil was effective in minimizing the contaminating effect of pig farming residues. The storage time for wastewaters from pig farming could be decreased from 120 to 90 days.

Crescimento e sobrevivência do camarão-rosa (Farfantepenaeus paulensis) na fase de berçário em meio heterotrófico

The objective of the present study was to evaluate the potential of a heterotrophic rearing media (microbial flocs) on the growth and survival of Farfantepenaeus paulensis reared in the nursery phase. For 30 days, F. paulensis post-larvae (0.019 ± 0.01g) were reared in nine 40-liter plastic tanks at the density of 500 post-larvae m -2. Three treatments with three replicates each were used: rearing in the presence of microbial flocs with ration supply (FLOC + R); rearing in the sole presence of flocs - no ration supplied (FLOC); and rearing in clear water plus with ration supply (AC + R). The presence of microbial flocs had no significant effect on growth and survival in the nursery rearing of F. paulensis.

Fitase em rações para tilápia-do-nilo na fase de crescimento

This research was carried out to compare the effect of phytase on performance, in the incorporation and excretion phosphorus in Nile tilápia. Four diets were used: one standard (contol), composed by 3,200 DE kcal ED/kg of ration and 30.0% CP and supplemented with phosphorus (4.0% of dicalcium phosphate), considering the treatment control, and others three, without phosphorus supplementation, with different phytase levels (1,000, 1,500, and 2,000 uf/kg), with four replication, per a period of 82 days. Circular tanks of fiber glass, with constant flow and aeration were used. The results demonstrated that the use of phytase in diets for fish production can reduce the levels of inorganic phosphorus in the diets and minimizing the impacts caused by phosphorus in the production system and in the natural environment and also can improve the productivity, increasing the amount of feed to be supplied and, consequently, facilitating the increase of biomass of fish to be used per production area. © 2007 Sociedade Brasileira de Zootecnia.