Effect of antioxidant supplementation and heat stress in a model of double vaccination in weaned piglets.

Piglet weaning is an interesting model of oxidative stress (OS), but due to large inter-individual variations, there is a need to standardize in vivo response by applying usual challenges, such as vaccination (vacc) and heat stress (HS). The objectives of this trial are the development of a reproducible model of OS and the determination of the most accurate blood biomarkers. The effect of a combination of antioxidants was also investigated.

360 starter pigs were randomly affected to eight groups in a 2×2×2 factorial design. Trial started at weaning (D0) and was divided into 2 phases: phase 1 (D0-14) and phase 2 (D14-41). Double vacc at D0 against PCV2 and porcine influenza, HS at days 9-10, 23-24 and 37-38 (37°C over 2×6h periods), or controls, were applied to piglets which were given during phase 1 NRC (2012) levels for vitamin E and selenium (low) or extra supplementation in vitamin E, selenium and SOD-rich melon pulp concentrate (high). Piglets were weighed at D0, D14, D28 and D41 and average daily feed intake (ADFI) and average daily gain (ADG) were measured for each phase. Blood was sampled at D13 and D40 and analyzed for GPx activity, lipid peroxides (LP), haptoglobin (HP) and half-haemolysis time (T1/2) of whole blood (WB) and red blood cells (RBC).

Double vacc impacts negatively ADFI (-3%) in phase 2 and ADG in post-weaning (p=0.03). Vacc negative effect was suppressed when piglets were supplemented with antioxidants: vacc piglets had lower ADG in phase 2 than non-vacc piglets in the low group (564 vs. 591 g/day, p=0.03), while there was no vacc effect in piglets for the high group (577 vs. 575 g/day for non-vacc and vacc piglets, respectively). Conversely, HS had worsening effect on performance in phase 1: 222 and 210 g/day for vacc piglets without and with HS, respectively (p< 0.05). Vacc increased inflammatory status (increased HP, p< 0.05) and OS (decreased plasma GPx activity and increased LP, p< 0.05) at D13 and D40, while antioxidants decreased OS (increased plasma GPx activity, decreased LP and increased T1/2 of WB and RBC, p< 0.05). Moreover, at D40 HS had negative effect on T1/2 of WB and RBC in vacc piglets (p< 0.01) and additive negative effects of HS and vacc were observed on LP.

Combining a double vacc against PCV2 and porcine influenza with repeated periods of HS appears efficient to develop an accurate model of OS in weaned piglet. Vacc has adverse effects on performance and increases OS and inflammatory status. HS appears here as a worsening factor of vacc, while combined antioxidants (vit E, organic selenium, SOD) helps restoring antioxidant status and zootechnical performance.

Disclosure of Interest: None Declared.