Leticia Fantini-Hoag

Objective: This 9-month study aimed to investigate the effects of the prolonged application of a dietary protease complex (PC) or humic substance (HS) on the growth, immunity, and survival of submarket Channel Catfish Ictalurus punctatus reared in an in-pond raceway (IPR) system. Methods: A 9-month feeding trial was conducted within nine IPR systems, each with 238 Channel Catfish (body weight [mean ± SE] = 206 ± 3 g). Raceways were randomly assigned to one of three 28% crude protein diet treatments in triplicate: a control diet (C28), a PC-supplemented diet (C28+PC), or an HS-supplemented diet (C28+HS). Growth sampling was performed every 30 d, and the final growth metrics, survival, immune responses, and gene expression were evaluated poststudy. Results: Monthly sampling showed that growth performance in all groups declined with temperature reduction and was lowest during winter. Both C28+PC and C28+HS groups showed the best percent biomass gain and feed conversion ratio until the sixth month of the study. However, as temperatures fell below 20°C, growth performance and survival were reduced in both treatment groups. Although the feed conversion ratio was high across groups (>3.0), it was significantly lower in the C28+PC group than in the C28 group. Conversely, the C28+HS group had lower biomass gain than the C28 group. Fulton’s condition factor was higher in the C28+HS group than in the C28+PC and C28 groups. At harvest, the C28 group had significantly higher survival (85%) than both the C28+PC (41%) and C28+HS (34%) groups. Serum lysozyme activity was higher in the C28+PC group than in the C28+HS or C28 group after 9 months. Additionally, the C28+HS group showed increased serum lysozyme activity compared to the C28 group. Conclusions: Although continuous administration of PC or HS in diets may enhance the nonspecific immune response and PC contributes to improved growth in catfish raised in IPR systems, prolonged exposure may compromise catfish immunity, increase susceptibility to environmental stress, and reduce survival.

The experiment was conducted to evaluate the composition of the hydroalcoholic extract of pitaya bark (Hylocereus guatemalensis) and its effects on the diet of male blue Betta splendens in terms of skin color, concerning the content of digestive enzymes, liver metabolism, and antioxidant activity. The fish were supplemented with hydroalcoholic extract of pitaya bark (HEPB) at the doses of 0.24, 0.45, and 0.90 mg kg−1 of feed for 21 days. The inclusion of 0.24 and 0.45 mg kg−1 of the HEPB promoted the best weight gain. and did not change the coloration of blue beta fish (P>0.05). The digestive activity showed an increase in alkaline phosphatase activity only in fish fed 0.45 mg kg−1 HEPB. The inclusion of 0.45 and 0.90 mg kg−1 from the HEPB promoted a decrease in hepatic ALT activity. An increase in CAT activity was observed in the skin of fish fed diets with added HEPB. In conclusion, the addition of hydroalcoholic extract of pitaya bark in the diet of Betta splendens is beneficial for the weight gain parameter and has a hepatoprotective effect but does not affect skin coloration.

Mycotoxins, produced by fungi, can contaminate fish food and harm their health. Probiotics enhance immune balance and primarily function in the animal intestine. This study aimed to assess aflatoxin’s impact on Piaractus mesopotamicus and explore probiotic-based additive (PBA) benefits in mitigating these effects, focusing on antioxidant activity, biochemical indices, and hepatic histopathology. Two experiments were conducted using P. mesopotamicus fry. The first experimental assay tested various levels of aflatoxin B1 (0.0, 25.0, 50.0, 100.0, 200.0, and 400.0 µg kg⁻¹) over a 10-day period. The second experimental assay examined the efficacy of the probiotic (supplemented at 0.20%) in diets with different levels of aflatoxin B1 (0.0, 25.0, and 400.0 µg kg⁻¹) for 15 days. At the end of each assay, the fish underwent a 24-hour fasting period, and the survival rate was recorded. Six liver specimens from each treatment group were randomly selected for metabolic indicator assays, including superoxide dismutase, catalase, alanine aminotransferase, aspartate aminotransferase, and albumin. Additionally, histopathological analysis was performed on six specimens. The initial study discovered that inclusion rates above 25.0 µg kg⁻¹ resulted in decreased activity of AST (aspartate aminotransferase), ALT (alanine aminotransferase), ALB (albumin), CAT (catalase), and SOD (superoxide dismutase), accompanied by liver histopathological lesions. In the second study, the inclusion of PBA in diets contaminated with AFB1 improved the activity of AST and ALT up to 25.0 µg kg⁻¹ of AFB1, with no histopathological lesions observed. The study demonstrated the hepatoprotective effects of PBA in diets contaminated with AFB1. The enzyme activity and hepatic histopathology were maintained, indicating a reduction in damage caused by high concentrations of AFB1 (400.0 µg kg⁻¹ of AFB1). The adverse effects of AFB1 on biochemical and histopathological parameters were observed from 25.0 µg kg⁻¹ onwards. Notably, PBA supplementation enhanced enzymatic activity at a concentration of 25 µg kg⁻¹ of AFB1 and mitigated the effects at 400.0 µg kg⁻¹ of AFB1. The use of PBAs in pacu diets is highly recommended as they effectively neutralize the toxic effects of AFB1 when added to diets containing 25.0 µg kg⁻¹ AFB1. Dietary inclusion of aflatoxin B1 at a concentration of 25.0 µg kg⁻¹ adversely affects the liver of Piaractus mesopotamicus (Pacu). However, the addition of a probiotic-based additive (PBA) to the diets containing this concentration of aflatoxin neutralized its toxic effects. Therefore, the study recommends the use of PBAs in Pacu diets to mitigate the adverse effects of aflatoxin contamination.

The objective of this study was to evaluate the effects of three levels of lipids in the diet on growth, metabolism, and intestinal and hepatic histopathology in discus fish (Symphysodon aequifasciatus). Fish were stocked in quadruplicate in aquarium (50L) and were fed experimental diets containing three levels (3%, 10%, and 14%) of dietary lipids (LP). At the end of the trial, no significant differences in growth performance were observed. Fish fed diets with 3% and 10% LP exhibited significantly higher protein efficiency rates compared to those fed the 14% LP diet. A significant increase in lipase and alkaline phosphatase activity was observed in fish fed 14% LP diets. The inclusion of 14% lipids in the diet led to a decrease in albumin activity and an increase in the height of the intestinal villi. Although no significant differences were observed in aspartate aminotransferase, alanine aminotransferase activities, and size of hepatocytes. The histopathology of the liver indicated reduced hepatocyte size, lipid vacuoles, and sinusoidal space in the group fed the 3% LP diet. In conclusion, the use of 10% LP diet was found to be more favorable for liver health and growth performance.

The U.S. catfish industry is seeking production systems that are efficient, intensive, and profitable. Growing foodsize and stocker-sized fish in the same pond is attractive as it is often difficult to obtain larger-sized stockers early each year. This case study evaluated the performance and economics of producing foodsize hybrid catfish and stocker-sized fingerlings in in-pond raceway systems (IPRS) placed into four 0.4 ha ponds. Growout raceways (RW1/RW2) in ponds 1 and 2 were 63 m³, and 45 m³ in ponds 3 and 4 (RW3/RW4). Each pond had one (14 m³) stocker unit raceway and a 5 HP of aeration that maintained adequate dissolved oxygen levels. Average growout production was 12,050 kg/ha in 63 m³ raceways and 12,078 kg/ha in 45 m³ raceways (228 days of production) and achieved harvest weights ranging from 564 to 661 g. The raceway stocker unit had production yields ranging from 3537 to 4388 kg/ha (143 days of production) and achieved harvest weights ranging from 123 to 234 g. Stocker units in ponds 1 and 2 generated 8540 stocker–fingerlings (21,102 fingerlings/ha) and units in ponds 3 and 4 generated 7954 fingerlings (19,654 fingerlings/ha). An investment of USD 39,996 was needed for ponds 1 and 2 and USD 21,196 for ponds 3 and 4. When scenarios were analyzed financially, positive financial net returns occurred when farm level investment decreased, leading to reduced payback periods, increased net present values, and higher internal rates of return. IPRS used stocker units to culture fingerlings for future stocking of foodsize fish. IPRS provided good inventory control, and high production yields compared to traditional pond culture of catfish.

Hybrid cachapinta (Pseudoplatystoma reticulatum × Pseudoplatystoma corruscans) has been a very popular fish and is well accepted by consumers internationally, however, there is a lack of information showing its advantages relative to its parental cachara (P. reticulatum) species. This study was undertaken to compare the processing yield and meat quality characteristics of cachara and the cachapinta hybrid raised in net cages. Cachara’s weight was 1.51 ± 0.27 kg and total length was 49.85 ± 6.22 cm at harvest and was not significantly different from hybrid cachapinta that weighed 1.50 ± 0.11 kg and measured 50.83 ± 3.91 cm. Additionally, the two groups were not statistically different on gutted fish dress out (cachara: 89.97 ± 1.28%; cachapinta: 90.23 ± 0.30%) and other processing yield parameters. Skinless shank fillets with an average weight of 503.77 ± 0.10 g (cachara) and 514.41 ± 0.04 g, (hybrid cachapinta) were evaluated for pH, water holding capacity, colour (L*, a*, b*), shear force and lipid oxidation (TBARS). There were no differences in the fillet meat quality between cachara and hybrid cachapinta tested in this study. In conclusion, both genetic groups had similar processing yield and fillet meat quality characteristics when produced in net cages.

Selection can affect growth, changing performance and asymptotic values. However, there is little information about the growth of families in fish breeding programs. The aim of this study was to evaluate the performance and growth of families of Nile tilapia AquaAmérica. Twenty AquaAmérica families cultivated in a net cage (13.5 m3) for 181 days were evaluated. The nonlinear Gompertz regression model was fitted to the data by the weighted least squares method, taking the inverse of the variance of weight in different families and at different ages as the weighting variable. The model was adjusted to describe the growth in weight and morphometric characteristics. Two families showed highest (P<0.05) weights at both 133 days (family AA10: 743.2 g; family AA16: 741.2 g) and 181 days (family AA10: 1,422.1 g; family AA16: 1,393.4 g) of the experiment. In both experimental periods, the males showed a heavier weight, with the greatest contrast between the sexes occurring at 181 days. The analysis of the three most contrasting families (AA1, AA9 and AA14) showed that the asymptotic value for weight was higher (P<0.05) in family AA9 (3,926.3 g) than in family AA14 (3,251.6 g), but specific growth rate and age at the inflection point did not differ significantly between families. In conclusion, two of the 20 families were superior; males exhibited a greater growth, mainly in the period of 181 days; and the growth curve differed between the families, especially for asymptotic weight.

The energy content is the most expensive component in the diet for production of swine. In this context, the objective of this study was to evaluate the profitability of nutritional plans with different net energy (NE) levels for barrows and gilts through sensitivity analysis. Nutritional plans with variable levels of NE were evaluated (2300; 2380; 2460; 2540; 2620 and 2700 kcal of NE/kg) in diets of 144 swines. The carcasses gross profit was determined based on bonus system (CGPbs) and or based solely on live weights (CGPlw). A sensitivity analysis was performed for each NE nutritional plan with different simulations of price quotes for the ingredients in the diet. The simulations carried out for the price of corn for nutritional plans for barrows, indicate that higher levels of net energy provided the highest CGPbs and CGPlw. For degummed soybean oil, the increase in the concentration of net energy in diets provided an increase of up to 6% in CGPbs and CGPlw. For gilts, the increase of energy levels in the diets from 2460 to 2700 kcal of net energy improved the gross profit by 17% when carcasses were sold based on bonus system (CGPbs) and CGPlw was higher when fed with the diet containing 2540 kcal of NE. The increase in the net energy level from 2300 to 2700 kcal in the diet of both barrows and gilts during the growth-finishing phase generated improvements in economic gains, regardless of the way in which the animals are marketed (CGPbs and CGPlw).

This study assesses the respiratory dynamics related to stress parameters and resting time before slaughter, in the quality of surubim (Pseudopatystoma spp.) fillets. A completely randomized design was conducted using five treatments: resting time before slaughter of 0, 2, 4, 8 and 24 hours, with 15 fish sampled per treatment. Time 0 corresponded to the treatment without resting time, where the fish were slaughtered immediately after arriving at the processing plant. The resting time did not affect the electrolyte balance, hemoglobin, plasma, hepatic glycogen, myofibrillar fragmentation index (MFI) and water holding capacity (WHC) of surubins. However, with increased resting time, there was a significant decrease in muscle glycogen and an increase in blood pH and blood bicarbonate levels. Additionally, respiratory parameters showed an increase in pO₂ and, consequently, in O₂ saturation and a decrease in pCO₂.The hematocrit and MCV values of the surubins after 24 hours of resting decreased significantly. In the first hours of resting, the highest values of erythrocytes and CHCM were observed. The lowest level of stress was observed for fish having 24 hours of resting. Fish having longer resting periods (8 and 24 hours) presented fillets with a higher pH (P <0.05) and the rigor mortis establishment time was shorter for the first 2 hours and 24 hours of resting time. There was a linear decrease in fillet lightness and an increase in the intensity of red (CIE a*) color up to 24 hours when resting was increased. In CIE b*, a linear decrease (P <0.05) of the yellow intensity of the fillets was observed as the surubim resting time increased. A resting time of 4 to 8 hours before slaughter is effective in reestablishing homeostasis after transporting surubim, providing fillets with higher quality and a greater length of the pre-rigor mortis period.

Foram avaliados tempo de indução, tempo de recuperação e respostas fisiológicas de cacharas Pseudoplatystoma reticulatum submetidos ao eugenol e mentol. Foram utilizados 42 indivíduos com peso total médio de 205,5 ± 59,13 g e comprimento total médio de 33,5 ± 2,36 cm, dos quais um grupo foi exposto ao eugenol 100 mg L-1 (n=14), outro grupo ao mentol 150 mg L-1 (n=14) e um grupo controle (n=14), não exposto a nenhum anestésico. No momento 0 e 24 h após indução foram realizadas colheitas sanguíneas nos peixes de cada tratamento (n=7) para avaliação dos parâmetros hematológicos e glicose plasmática. Os resultados foram submetidos à análise de variância (P<0,05) e as médias quando significativas foram comparadas pelo teste de Tukey (P<0,05). Ambos os anestésicos em suas respectivas concentrações induziram os peixes à anestesia cirúrgica. O tempo de recuperação dos animais apresentou redução significativa (P<0,05) quando expostos ao mentol 150 mg L-1. Houve efeito de interação entre os fatores para o parâmetro hematológico VCM, visto que os peixes anestesiados com eugenol apresentaram redução significativa (P<0,05) do mesmo 24 h após anestesia. Os valores de glicose plasmática não diferiram entre si 0 h após indução, sendo que 24 h depois, tanto os peixes do grupo controle quanto os expostos ao eugenol e mentol apresentaram redução significativa (P<0,01) dos níveis plasmáticos. O eugenol a 100 mg L-1 e o mentol a 150 mg L-1 podem ser utilizados seguramente na indução anestésica de cacharas durante a realização de biometrias.