Quercetin and flaxseed included in the diet of fattening lambs: Effects on immune response, stress during road transport and ruminal acidosis

Thirty-two lambs were divided in 4 groups with 2 replicates each (8 batches in total) according to their body weights. The lambs were fed a total mixed ration (TMR) formulated either with palm oil (CTRL, 2 replicates, 4 animals per replicate; 34 g palmoil kg−1 TMR) or flaxseed (FS, 2 replicates, 4 animals per replicate; 85 g flaxseed kg−1 TMR). Four more batches were fed the same TMRs but enriched with quercetin (QCT, 2 replicates, 4 animals per replicate, 34 g palm oil plus 2 g quercetin kg−1 TMR; FS-QCT, 2 replicates, 4 animals per replicate, 85 g flaxseed plus 2 g quercetin kg−1 TMR). Three weeks after starting with the experimental diets, the animals were immunized by a subcutaneous injection of ovalbumin, and blood samples were collected at days 0, 4, 9, 14 and 17 post-immunization to measure antibodies against ovalbumin. Afterwards, all of the lambs were subjected to a 4-h transportation-stress period to study the evolution of haematological and biochemical parameters during road transport and, finally, slaughtered. Mean ova-specific IgG titres were significantly lower in the lambs fed FS on days 14 and 17 when compared to CTRL group (FS×DAY, P=0.033). Additionally, FS reduced white blood cells counts and tissue damage (creatine phosphokinase, P<0.05) during road transport. Consequently, flaxseed showed some immunological properties and protection against tissue damage during road transport. Regarding ruminal acidosis, both quercetin and flaxseed seemed to be adequate to reduce the level of parakeratosis.