Carla C. Zeppenfeld

Anesthesia of silver catfish with eugenol: time of induction, cortisol response and sensory analysis of fillet

O objetivo deste estudo foi identificar o tempo de inducao e recuperacao anestesica de jundias (Rhamdia quelen) expostos ao eugenol, bem como a eficacia desse anestesico na inibicao do estresse e realizar analise sensorial dos files dos peixes expostos a essa substância. Os jundias foram expostos ao ar por um minuto para realizacao da biometria, e o sangue foi coletado zero, uma e quatro horas depois. O eugenol pode ser usado na faixa de 20-50mg L-1 para a inducao da anestesia em jundias, e o tempo de recuperacao da anestesia nao foi afetado pela concentracao do eugenol. O grupo de controle mostrou niveis significativamente mais elevados do cortisol quatro horas apos a biometria que no tempo zero. Os peixes anestesiados com eugenol (50mg L-1) apresentaram niveis significativamente mais baixos do cortisol plasmatico do que peixes do grupo de controle do mesmo tempo. Esses dados indicam que o eugenol inibe o aumento do cortisol no sangue. O teste sensorial demonstrou que o eugenol modifica o sabor dos files e consequentemente e contra-indicado para a anestesia do jundia quando o file for destinado ao consumo humano.

Desempenho de cordeiros machos inteiros, machos castrados e fêmeas, alimentados em confinamento

The study was carried with the objective to evaluate the effect of the sex upon the weight gain, dry matter intake and food conversion of feedlot lambs and slaughtered at one hundred days of age. Eighteen lambs (six whole males, six castrated males and six females) descendents of a Texel male with (Texel x Ideal) female sheeps, were used. The animals (sheeps + lambs) were confined in individuals bails 24 hours after delivery until the weaning at the 50 days. After, they remained along until the slaughter at the age of 100 days. The food used was corn silage + concentrated (corn + soybean meal + minerals), in the proportion 58:42 in dry matter. The values obtained for weight gain, dry matter intake (kg/animal/day), % live weight and g/metabolic size and food conversion, did not differ (P>0,05) among the sex of the lambs. The results obtained showed that whole males lambs, castrated males lambs and females lambs, present performance similar at the age of 100 days.

Efficacy of eugenol and the methanolic extract of Condalia buxifolia during the transport of the silver catfish Rhamdia quelen

This study evaluated extracts of Condalia buxifolia as anesthetics for the silver catfish Rhamdia quelen. The effectiveness of eugenol and of the methanolic extract (ME) of C. buxifolia during the transport of this species was also assessed. Fish of two different weights (1.50±0.02 g and 165.70±22.50 g) were transferred to aquaria containing water with the C. buxifolia ME or with fractions obtained from the ME, such as the n-hexane, dichloromethane, ethyl acetate, n-butane and aqueous fractions, at concentrations from 0-300 °L L-1. The C. buxifolia ME in the 0.5-120 °L L-1range caused only light sedation, and the fractions did not have an effect on the fish. In the second experiment, another group of fish was transported for 12 h in 15 plastic bags. The fish were divided into five groups: control, 1 or 2.5 °L L-1 eugenol and 25 or 50 °L L-1C. buxifolia ME. The non-ionized ammonia levels were lower at the end of transport in the groups with the compounds than in that with water alone. Moreover, both compounds decreased the Na+, Cl-, and K+ net effluxes; therefore, their addition to the water during transport is advisable because they reduce fish mortality and ion loss.

Crescimento de regiões da carcaça de cordeiros abatidos com diferentes pesos

This work was performed at the Ovine Section of Animal Science Department, at Federal University of Santa Maria, Brazil. The purpose of this experiment was to determine the growth of the carcass cuts and percentages in relation to the empty body weight and cold carcass weight of lambs slaughtered at different weights. Twenty-two intact male lambs, sired by Texel males, from crossbreed Texel-Ideal dams were used. Four lambs were slaughtered at the beginning of the experiment (24 hours after birth) and three groups of six lambs were slaughtered at weaning and when reaching the weight of 28 and 33kg. The lambs were confined in individual stall together, with their respective mothers until weaning (45 days of age). To study the growth of the different cuts of the carcass, regression equation of the log. of the weight of each part, as a function of the log. of the empty body weight or cold carcass weight were fitted. The percentages of hindquarter, shoulder and neck in relation to the empty body weight were similar (P>0.05) in the weights studied, and of rib and backbone were different (P<0.05). In relation to the cold carcass weight the percentage of hindquarter, rib and neck showed difference (P<0.05). Among the cuts, the rib was late matured and the other cuts were early matured.

Using the essential oil of Aloysia triphylla (L'Her.) Britton to sedate silver catfish (Rhamdia quelen) during transport improved the chemical and sensory qualities of the fish during storage in ice.

UNLABELLED Exposure of silver catfish to 40 μL/L of the essential oil of Aloysia triphylla (AT) during in vivo transport delayed the onset and resolution of rigor mortis as well as the degradation of IMP into HxR compared to the control. The fish that were treated with 30 or 40 μL/L of AT received lower sensory demerit scores after 10 d of storage in ice compared to the control, and the fish that were treated with 40 μL/L of AT had a longer sensory shelf life than did the control. These results indicated that using AT as a sedative in the water in which the silver catfish were transported extended their freshness and increased their shelf life during refrigerated storage. PRACTICAL APPLICATION Interest in natural anesthetics, such as Aloysia triphylla, has increased in the field of commercial aquaculture because they reduce the number of fish lesions acquired during capture, handling, and transportation. Fish sedated with the essential oil of A. triphylla at 40 μL/L during transport before slaughter exhibited a delay in the loss of freshness and an increased shelf life in ice. In addition to improving animal welfare before slaughter, the essential oil appears to be a promising product for improving fish conservation in the food industry.

Lippia alba essential oil promotes survival of silver catfish (Rhamdia quelen) infected with Aeromonas sp.

In vitro and in vivo activity of the Lippia alba essential oil (EO) against Aeromonas sp. was evaluated. In the in vitro assay the minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of EO for Aeromonas cells were determined using the microdilution method. Twenty five strains of Aeromonas sp. isolated from infected fish obtained from local fish farms were used. MIC and MBC values were 2862 and 5998 µg mL-1 for L. alba EO and 0.5 and 1.2 µg mL-1 for gentamicin, respectively. In the in vivo assay silver catfish juveniles (Rhamdia quelen) (7.50 ± 1.85 g and 10.0 ± 1.0 cm) with typical injuries associated to Aeromonas infection were divided into four treatments (in triplicate n=10): untreated fish (negative control), 10 mg L-1 of gentamicin, and 20 or 50 µL L-1 of EO. Fish were maintained in aerated 20 L plastic boxes. After 10 days survival of silver catfish infected with Aermonas sp. and treated with essential oil (50 µL L-1) was greater than 90%.

Biochemical parameters of silver catfish (Rhamdia quelen) after transport with eugenol or essential oil of Lippia alba added to the water

The transport of live fish is a routine practice in aquaculture and constitutes a considerable source of stress to the animals. The addition of anesthetic to the water used for fish transport can prevent or mitigate the deleterious effects of transport stress. This study investigated the effects of the addition of eugenol (EUG) (1.5 or 3.0 µL L-1) and essential oil of Lippia alba (EOL) (10 or 20 µL L-1) on metabolic parameters (glycogen, lactate and total protein levels) in liver and muscle, acetylcholinesterase activity (AChE) in muscle and brain, and the levels of protein carbonyl (PC), thiobarbituric acid reactive substances (TBARS) and nonprotein thiol groups (NPSH) and activity of glutathione-S-transferase in the liver of silver catfish (Rhamdia quelen; Quoy and Gaimard, 1824) transported for four hours in plastic bags (loading density of 169.2 g L-1). The addition of various concentrations of EUG (1.5 or 3.0 µL L-1) and EOL (10 or 20 µL L-1) to the transport water is advisable for the transportation of silver catfish, since both concentrations of these substances increased the levels of NPSH antioxidant and decreased the TBARS levels in the liver. In addition, the lower liver levels of glycogen and lactate in these groups and lower AChE activity in the brain (EOL 10 or 20 µL L-1) compared to the control group indicate that the energetic metabolism and neurotransmission were lower after administration of anesthetics, contributing to the maintenance of homeostasis and sedation status.

The use of nitazoxanide against the pathogens Ichthyophthirius multifiliis and Aeromonas hydrophila in silver catfish (Rhamdia quelen)

The antiparasitic and antibacterial activities of nitazoxanide (NTZ) against Ichthyophthirius multifiliis (Ich) and Aeromonas hydrophila, respectively, were evaluated in silver catfish juveniles (Rhamdia quelen). In the first experiment, fish naturally infected by Ich were treated with different concentrations of NTZ. Fish mortality and the number of trophonts/juveniles were evaluated. In the second experiment, the antimicrobial potential in vitro (MIC test) and preventive potential in vivo against A. hydrophila was evaluated. The treatment with 1.5mgL(-1) NTZ showed the best result against Ich, with a significant reduction of trophonts and fish mortality of 10%. NTZ did not show in vitro activity against A. hydrophila at concentrations tested, but showed a probable preventive activity in vivo. However, these results are preliminary and more studies should be conducted.

Changes in the cerebral phosphotransfer network impair energetic homeostasis in an aflatoxin B 1 -contaminated diet

The phosphotransfer network system, through the enzymes creatine kinase (CK), adenylate kinase (AK), and pyruvate kinase (PK), contributes to efficient intracellular energetic communication between cellular adenosine triphosphate (ATP) consumption and production in tissues with high energetic demand, such as cerebral tissue. Thus, the aim of this study was to evaluate whether aflatoxin B1 (AFB1) intoxication in diet negatively affects the cerebral phosphotransfer network related to impairment of cerebral ATP levels in silver catfish (Rhamdia quelen). Brain cytosolic CK activity decreased in animals fed with a diet contaminated with AFB1 on days 14 and 21 post-feeding, while mitochondrial CK activity increased, when compared to the control group (basal diet). Also, cerebral AK and PK activity decreased in animals fed with a diet contaminated with AFB1 on days 14 and 21 post-feeding, similarly to the results observed for cerebral ATP levels. Based on this evidence, inhibition of cerebral cytosolic CK activity is compensated by stimulation of mitochondrial CK activity in an attempt to prevent impairment of communication between sites of ATP generation and ATP utilization. The inhibition of cerebral AK and PK activity leads to impairment of cerebral energy homeostasis, decreasing the brain’s ATP availability. Moreover, the absence of a reciprocal compensatory mechanism between these enzymes contributes to cerebral energetic imbalance, which may contribute to disease pathophysiology.

Aflatoxin B 1 -contaminated diet disrupts the blood–brain barrier and affects fish behavior: Involvement of neurotransmitters in brain synaptosomes

It is known that the cytotoxic effects of aflatoxin B1 (AFB1) in endothelial cells of the blood-brain barrier (BBB) are associated with behavioral dysfunction. However, the effects of a diet contaminated with AFB1 on the behavior of silver catfish remain unknown. Thus, the aim of this study was to evaluate whether an AFB1-contaminated diet (1177 ppb kg feed-1) impaired silver catfish behavior, as well as whether disruption of the BBB and alteration of neurotransmitters in brain synaptosomes are involved. Fish fed a diet contaminated with AFB1 presented a behavioral impairment linked with hyperlocomotion on days 14 and 21 compared with the control group (basal diet). Neurotransmitter levels were also affected on days 14 and 21. The permeability of the BBB to Evans blue dye increased in the intoxicated animals compared with the control group, which suggests that the BBB was disrupted. Moreover, acetylcholinesterase (AChE) activity in brain synaptosomes was increased in fish fed a diet contaminated with AFB1, while activity of the sodium-potassium pump (Na+, K+-ATPase) was decreased. Based on this evidence, the present study shows that silver catfish fed a diet containing AFB1 exhibit behavioral impairments related to hyperlocomotion. This diet caused a disruption of the BBB and brain lesions, which may contribute to the behavioral changes. Also, the alterations in the activities of AChE and Na+, K+-ATPase in brain synaptosomes may directly contribute to this behavior, since they may promote synapse dysfunction. In addition, the hyperlocomotion may be considered an important macroscopic marker indicating possible AFB1 intoxication.