Immunostimulants represent a modern and promising tool in aquaculture, enhancing the resistance of cultured fish to disease and stress. This study investigated the effect of a combination of dietary glucans, alpha-tocopherol and ascorbic acid on the innate immune response of cultured sea bass (Dicentrarchus labrax). After 5 weeks of adaptation on a commercial diet containing 100 p.p.m. ascorbic acid and 200 p.p.m. alpha-tocopherol, sea bass were switched to a diet supplemented with 2% beta-1.3/beta-1.6 glucans and ascorbic acid and alpha-tocopherol at 500 p.p.m. The supplemented diet was given at 2% of body weight per day over a 2-week period, every 3 months. Plasma lysozyme concentration, content and distribution of major plasma proteins and complement activity were measured prior to feeding the supplemented diet and after 40 weeks. Alternative pathways of complement activation and lysozyme activity were both significantly enhanced in fish fed on glucans and elevated doses of vitamins. No significant differences were observed in protein content or in albumin/globulin ratio. Compared to lysozyme activity, which showed marked individual variation, complement-mediated haemolytic activity has been shown to be a more reliable indicator of sea bass immunocompetence. Further studies are in progress to clarify the effect of each dietary component on the innate immune response and disease resistance.

In pigs, the genetic selection for lean, large muscle blocks and fast growth has been linked to an increased prevalence of metabolic diseases such as porcine stress syndrome and mulberry heart disease. These diseases are associated with cardiovascular inadequacy, which may lead to oxidative stress. In the present study, reactive oxygen metabolites (ROMs) and the anti-oxidant power (OXY) in sera of different swine groups were investigated. The following groups were selected (each around 80 kg body weight): wild boars (WB), Cinta Senese (CS), and Landrace x Large White (LxLW), the latter as both specific pathogen-free (SPF) and intensively farmed animals. In addition, a group of LxLW agonic sows (AS) was also investigated; this group is known to be under oxidative stress. Two colorimetric micro-methods were used to measure ROMs and OXY; ROMs were expressed as mM H(2)O(2) and OXY as microM HOCl neutralised. Between groups, average ROM and OXY values were found to be significantly different by one-way ANOVA (P < 0.001). ROM levels were lower in WB (13.41 +/- 1.85) and CS (19.27 +/- 1.68), and highest in LxLW (42.00 +/- 1.36). OXY values ranged from 260.10 +/- 22.13 (WB) to 396.90 +/- 9.83 (LxLW). Only one swine group (the CS group) showed a significant, positive correlation between ROM and OXY values. The AS group even showed a negative correlation between ROM and OXY values. These results imply satisfactory environmental coping occurred only within the CS group. Results are discussed in the light of animal welfare legislation, food safety and consumers' protection.

The ability of pigs to neutralize the reactive oxygen species (ROS) plays a key role in their welfare. Two micromethods were developed to evaluate the oxidative stress and the anti-oxidative response in sera. We tested these methods for linearity, repeatability and reproducibility. A hydroxyl radicals (HR) test, based on the Fenton reaction, showed a linearity between 0.26 and 4.5 mM H2O2 (r = 0.997), with a coefficient of repeatability (CVr) of 1.9 and a coefficient of reproducibility (CVR) of 2.9. An anti-oxidant power (AOP) test, based on the capability of sera to neutralize a titred hypochlorous acid solution (HClO), showed a linearity between 55 and 880 microM HClO neutralized (r = 0.984), with CVr = 3.1 and CVR = 4.9. We assessed the applicability of such tests in field conditions on three different farms. Farm A recorded a positive anamnesis of Mulberry heart disease. Dietary Vitamin E supplementation was given at 50 p.p.m. in farms A and B and at 150 p.p.m. in farm C, respectively. The group from farm A showed HR sera levels higher than those of farm B and farm C (farm A, mean = 31.61 +/- 2.87 mM H2O2, n = 10; farm B, 28.53 +/- 2.30, n = 10; and farm C, 25.63 +/- 1.03, n = 10; P < 0.01). The AOP test was not able to discriminate between farms. The AOP levels found (mean = 472.50 microM HClO neutralized: n = 30) probably represent the maximum response of the organism to compensate the oxidative stress. HR and AOP are stable in sera stored at +4 degrees C. We discuss the application of such methods for the assessment of farmed animals' welfare.

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