- Livestock Sectors
This study by Henrik Sundh, Bjorn Olav Kvamme, Frode Fridell, Rolf Erik Olsen, Tim Ellis, Geir Lasse Taranger and Kristina Sundell suggests that the intestinal barrier function of Atlantic salmon post smolts is reduced by common sea cages environments. It may also be used as a physiological indicator of welfare.
Fish farmed under high intensity aquaculture conditions are subjected to unnatural environments that may cause stress. Therefore awareness of how to maintain good health and welfare of farmed fish is important.
For Atlantic salmon held in sea cages, water flow, dissolved oxygen (DO) levels and temperature will fluctuate over time and the fish can at times be exposed to detrimentally low DO levels and high temperatures. This experimental study investigates primary and secondary stress responses of Atlantic salmon post smolts to long-term exposure to reduced and fluctuating DO levels and high water temperatures, mimicking situations in the sea cages. Plasma cortisol levels and cortisol release to the water were assessed as indicators of the primary stress response and intestinal barrier integrity and physiological functions as indicators of secondary responses to changes in environmental conditions.
Plasma cortisol levels were elevated in fish exposed to low (50 per cent and 60 per cent saturation) DO levels and low temperature (nine degreesC), at day 9, 29 and 48. The intestinal barrier function, measured as electrical resistance (TER) and permeability of mannitol at the end of the experiment, were reduced at 50 per cent DO, in both proximal and distal intestine.
When low DO levels were combined with high temperature (16degreesC), plasma cortisol levels were elevated in the cyclic 1:5 h at 85 per cent:50 per cent DO group and fixed 50 per cent DO group compared to the control (85 per cent DO) group at day 10 but not at later time points. The intestinal barrier function was clearly disturbed in the 50 per cent DO group; TER was reduced in both intestinal regions concomitant with increased paracellular permeability in the distal region.
This study reveals that adverse environmental conditions (low water flow, low DO levels at low and high temperature), that can occur in sea cages, elicits primary and secondary stress responses in Atlantic salmon post smolts. The intestinal barrier function was significantly affected by prolonged hypoxic stress even when no primary stress response was observed.
This suggests that intestinal barrier function is a good experimental marker for evaluation of chronic stress and that it can be a valuable tool to study the impact of various husbandry conditions on health and welfare of farmed Atlantic salmon. [Source: The Fish Site]
The British Veterinary Association (BVA) is deeply concerned by a European Parliament resolution calling on the Commission to legislate against the prophylactic use of antibiotics (antimicrobials) in livestock farming.
The move is part of a larger motion drawing attention to the problem of antimicrobial resistance and calling for measures across Europe to reduce the increase in resistance. It was passed by MEPs on 27 October 2011.
Commenting, Carl Padgett, President of the BVA, said:
“There is a huge amount to be welcomed in this resolution, which calls for greater surveillance, increased use and understanding of data, and a responsible approach to the use of antimicrobials across Europe.
“However, the call for a ban on the prophylactic use of antibiotics in livestock farming could have a detrimental impact on animal health and welfare by reducing the ability of veterinary surgeons to treat animals in a timely and appropriate fashion.
“While we understand the desire to put an end to blanket prophylactic treatment with antimicrobials, this measure shows a lack of understanding of how vets treat infection on the farm.
“Vets should be able to use their clinical and professional judgement; otherwise we risk a situation whereby they are unable to administer an antimicrobial to an injured animal to prevent infection, or to the penmates of sick animals on farm who are likely to also be infected.
“In a practical sense a complete ban on the prophylactic use of antimicrobials puts the vets in a very difficult position and the result could compromise animal health and welfare.” [Source: www.BVA.co.uk]