Extruded linseed supplementation in the diet of dairy sheep: The effects on immune response and oxidative stress as affected by the physiological state

Several investigations have studied the influence of polyunsaturated fatty acids on the immune function of ruminants but many contradictory observations have been reported in this field. The aim of this study was to evaluate the influence of an extruded linseed dietary supplementation on the immune response and oxidative stress in the transition dairy ewe. The experiment was performed using 58 Sarda pluriparous ewes, 42 pregnant (T) and 16 non-pregnant and non-lactating (NP). Both groups were fed an isoenergetic and isonitrogenous diet from 60 d before to 15 d after lambing of the T ewes. Within each physiological state, one sub-group received a commercial pelleted concentrate (CTR) and the other an extruded linseed-enriched (10 g/100 g) concentrate (EL). Blood samples were collected from all animals at −28, −21, −14, −7, +3 and +15 d to parturition, based on expected date of lambing of the T ewes, to evaluate the innate immunity (serum lysozyme, haemolytic complement and bactericidal activity), the acquired immunity and the oxidative stress. The dietary supplementation with extruded linseed did not markedly influence the innate immunity response of the animals. The antibody production against Salmonella enterica subsp. enterica serovar Abortusovis was shown to be increased by the linseed-enriched diet in the T ewes (2.37 vs. 2.19 log10 for the T and the NP ewes, respectively). As for the cell-mediated immunity, no differences between dietary treatments were observed. The extruded linseed-enriched diet was able to induce a transitory overproduction of oxidants in the NP ewes, whereas no effects were observed in the T ewes. In conclusion, under the adopted experimental conditions, the use of extruded linseed in the diet did not greatly affect the oxidative state and the immune response of the transition ewe.