Hydrogen peroxide (H2O2) and metrifonate (Mtf) are common products used in ectoparasite infestations on fish cultures. The therapeutic efficacy of H2O2 and Mtf on a common monogenean parasite, Ligictaluridus floridanus, was evaluated in channel catfish ( Ictalurus punctatus ). In vitro trials were conducted using excised fish gills naturally infected with L. floridanus, which were immersed in H2O2 (150, 300, and 570 mg L(-1)) and Mtf (0.25, 0.5, and 0.75 mg L(-1)) solutions. The efficacy of the treatments was based on the survival time of the parasites, observed microscopically. In addition, an in vivo trial using catfish juveniles, naturally infected with L. floridanus, was also performed. One group received immersion baths of 570 mg L(-1) H2O2 (3%) during 4 min; the Mtf (90%) group received 0.5 mg L(-1) Mtf for 10 min. Treatments were done on days 3, 7, and 11 of the experiment. Results indicate that baths with Mtf do not significantly reduce the mean intensity of the parasite per gill arch, nor do they reduce the in vitro survival time of parasites during treatment; H2O2 baths at 570 mg L(-1) during 4 min were effective (P < 0.05) against adult and juvenile stages of L. floridanus. This study supports the use of H2O2 as an effective antiparasitic agent against I. punctatus .
ABSTRACT. Biological response modifiers such as pro and prebiotics have been recently used in aquaculture showing abilities as immunostimulants, enhancing resistance to different fungal, bacterial and parasitic pathogens and tolerance to environmental stress. This experiment evaluated three different concentrations (0.05, 0.1 and 0.5%) of β-1,3/1,6 glucans on nonspecific immune parameters of channel catfish Ictalurus punctatus. Results showed that intake supplementation with 0.05% of β-1,3/1,6 glucans provides a greater immunostimulation over the fourth treatment week. Significant higher differences (P < 0.05) were obtained on parameters related to phagocytic activity on blood cells, also other assays showed more reactive cells to nitroblue tetrazolium (NbT) stain on spleen and head kidney analysis. We conclude that the use of 0.05% of β-1,3/1,6 glucans added to a commercial diet improves nonspecific immune system of channel catfish I. punctatus.
Seagrasses are critical habitats for the recruitment and growth of juvenile penaeid shrimps within estuaries and coastal lagoons. The location of a seagrass bed within the lagoon can determine the value of a particular bed for shrimp populations. Consequently, differences in the abundance of shrimp can be found in seagrasses depending on their location. As shrimp density increases, density-dependent effects on biological parameters are more likely to occur. However, knowledge about density-dependent processes on shrimp populations in nursery habitats remains limited. The present investigation was undertaken to examine the effects of population density on shrimp condition in two selected seagrass beds, located at different distance from a tidal inlet, one 25 km away (distant) and the other 1 km away (nearby), in a subtropical coastal lagoon. The study was based on monthly samplings during one year in Laguna Madre (Mexico), performing a total of 36 shrimp trawls (100 m2 each one) within each seagrass bed (n = 3 trawls per bed per month for 12 months). Shrimp density was related to the proximity to the tidal inlet (higher density was consistently observed in the nearby seagrass bed), which in turn adversely affected the condition of both species studied (Penaeus aztecus and P. duorarum). In this regard, the present study provides the first evidence of density-dependent effects on shrimp condition inhabiting a nursery habitat. Both shrimp species exhibited a negative relationship between condition and shrimp density. However, this pattern differed depending on the proximity to the tidal inlet, suggesting that shrimp populations inhabiting the nearby seagrass bed are exposed to density-dependent effects on condition; whereas, such effects were not detected in the distant seagrass bed. Shrimp density within the distant seagrass bed was probably below carrying capacity, which is suggested by the better shrimp condition observed in that area of the lagoon. Intra and interspecific competition for food items is surmised to occur, predominantly within seagrass beds near the tidal inlet. However, this hypothesis needs to be tested in future studies.
Lactoferrin is a mammalian cationic iron‐binding glycoprotein of the innate immune system that belongs to the transferrin family of proteins. Present in colostrum, milk and tears, and exhibiting a wide range of biological properties in vitro and in vivo, lactoferrin is a nutraceutical component used as a food supplement for humans. Evidence from veterinary medicine and animal production suggests the potential use of lactoferrin as a microbicide, microbiostatic, microbiota modulator or immunostimulant. Bovine lactoferrin is the most common type of lactoferrin in animal production research, because it is more easily produced and sold all over the world. Administering bovine lactoferrin to dairy cattle, chickens and pigs causes several physiological changes that may affect immune system behaviour, microbiota status and iron homeostasis. This could increase resistance to pathogens and, in some cases, improve growth performance. The present review analyses the in vitro and in vivo effects of bovine lactoferrin on fish species for human consumption. Although there is no consensus on how bovine lactoferrin can modify the physiology of fish in vivo, the results of in vitro assays suggest a similar molecular mechanism to that previously described in mammals.
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