Fish welfare and biological rhythms : time to regulate

In this article we introduce the concept of biological rhythms in fish welfare and critically discuss a neglected aspect: time-dependent issues. First we should consider that fish, like most living organisms, posses a clock that drives rhythmic biological functions. Therefore, fish stress responses are strongly affected by the time of stressor exposure (e.g. day/night) according to their daily pattern of behavior (diurnal/nocturnal). Furthermore, drugs affect fish differently depending of time of administration. For instance, commonly used substances such as anesthetics may have strikingly different effects depending on the time of day. MS-222 -the most widely used fish anesthetics- has fastest effects and higher toxicity when applied during daytime, but it is much less toxic at night. Surprisingly, no attention has been paid to this time-dependent factor when establishing dosages and protocols for fish anesthesia and euthanasia. In summary, there is a need to take into account properly the role of biological rhythms when discussing fish welfare issues and regulations by the Institutional Animal Care and Use Committee (IACUC).En este artículo se introduce el concepto de ritmos biológicos en el bienestar de peces, y se discute críticamente un tema olvidado: aspectos dependientes del tiempo. Primero debemos considerar que los peces, al igual que la mayoría de organismos vivos, poseen un reloj interno que dirige los ritmos biológicos. Por tanto, las respuestas al estrés de los peces están fuertemente afectadas por la hora de exposición al agente estresante (p.e. día/noche) en función de su patrón diario de comportamiento (diurno/nocturno). Además, los fármacos pueden afectar de forma diferente a los peces dependiendo de la hora de la administración. Por ejemplo, sustancias comúnmente usadas como los anestésicos pueden tener efectos llamativamente distintos dependiendo de la hora del día. El MS-222, el anestésico más ampliamente utilizado en peces, tiene efectos más rápidos y mayor toxicidad cuando es aplicado por el día, pero es mucho menos tóxico por la noche. Sorprendentemente, no se ha prestado atención a este factor temporal cuando se establecen dosis y protocolos para la anestesia o eutanasia de peces. En resumen, es necesario tener en cuenta adecuadamente el papel de los ritmos biológicos cuando se discute el bienestar de peces y su regulación por los comités de uso y cuidado de animales

Dietary supplementation with a specific mannan-rich yeast parietal fraction enhances the gut and skin mucosal barriers of Atlantic salmon (Salmo salar) and reduces its susceptibility to sea lice (Lepeophtheirus salmonis)

Background: Increasing reliance on non-medicinal interventions to control sea lice in the Atlantic salmon (Salmo salar) farming industry imposes a high level of skin mucosal disturbance and indirect health issues. Dietary supplementation with yeast-based MOS products is widely used to support intestinal homeostasis across farmed species. Evidence of their effect on skin mucosa is increasing in aquatic species but it remains inconsistent and someway short of a clear contribution to sea lice management. A tank-based trial was performed to test the effect of a yeast-based MOS functional compound (sMOS) on the skin mucosal layer and its protective effects against sea lice (Lepeophtheirus salmonis). Results: The test compound significantly increased skin mucus (+46%) and goblet cell density (+25%) after 6 weeks of dietary supplementation when positive effects on intestinal villi-length (+10.9%) and goblet cell density (+80.0%) were also documented. Following dietary supplementation, a 16.6% reduction in susceptibility to an acute standard copepodid challenge was measured alongside an earlier increase in skin lysozyme activity widely used as an index of innate immunity. Conclusion: The study provides functional evidence that the benefits of dietary sMOS reach beyond the intestine to the skin mucosa. Bolstering of the Atlantic salmon skin barrier and immune functions and the resulting lower susceptibility to sea lice has the potential to reduce the need for delousing interventions and the impact of non-medicinal interventions on the animal's health and welfare

Fish welfare and biological rhythms : time to regulate

In this article we introduce the concept of biological rhythms in fish welfare and critically discuss a neglected aspect: time-dependent issues. First we should consider that fish, like most living organisms, posses a clock that drives rhythmic biological functions. Therefore, fish stress responses are strongly affected by the time of stressor exposure (e.g. day/night) according to their daily pattern of behavior (diurnal/nocturnal). Furthermore, drugs affect fish differently depending of time of administration. For instance, commonly used substances such as anesthetics may have strikingly different effects depending on the time of day. MS-222 -the most widely used fish anesthetics- has fastest effects and higher toxicity when applied during daytime, but it is much less toxic at night. Surprisingly, no attention has been paid to this time-dependent factor when establishing dosages and protocols for fish anesthesia and euthanasia. In summary, there is a need to take into account properly the role of biological rhythms when discussing fish welfare issues and regulations by the Institutional Animal Care and Use Committee (IACUC).En este artículo se introduce el concepto de ritmos biológicos en el bienestar de peces, y se discute críticamente un tema olvidado: aspectos dependientes del tiempo. Primero debemos considerar que los peces, al igual que la mayoría de organismos vivos, poseen un reloj interno que dirige los ritmos biológicos. Por tanto, las respuestas al estrés de los peces están fuertemente afectadas por la hora de exposición al agente estresante (p.e. día/noche) en función de su patrón diario de comportamiento (diurno/nocturno). Además, los fármacos pueden afectar de forma diferente a los peces dependiendo de la hora de la administración. Por ejemplo, sustancias comúnmente usadas como los anestésicos pueden tener efectos llamativamente distintos dependiendo de la hora del día. El MS-222, el anestésico más ampliamente utilizado en peces, tiene efectos más rápidos y mayor toxicidad cuando es aplicado por el día, pero es mucho menos tóxico por la noche. Sorprendentemente, no se ha prestado atención a este factor temporal cuando se establecen dosis y protocolos para la anestesia o eutanasia de peces. En resumen, es necesario tener en cuenta adecuadamente el papel de los ritmos biológicos cuando se discute el bienestar de peces y su regulación por los comités de uso y cuidado de animales