Physiological responses and blood gas exchange following long-distance transport of piglets weaned at different ages over unpaved or paved roads

This study investigated the physiological changes associated with the prolonged transport of piglets weaned at three different ages: 10 (W-10), 15 (W-15) and 21(W-21) days under two experimental conditions: over an unpaved (UPR) vs. a paved road (PR). During the experiment the piglets were exposed to two stressors simultaneously: weaning and transport in a vehicle to the farm. The duration of each trip was approximately 6 h. The stress responses to weaning and transport were determined using blood physiological and metabolic profiles. Four blood sampling procedures were performed with all groups: 24 h before weaning while the piglets were at rest inside the piglet boxes (baseline levels); immediately after weaning but before transport; the third sample was collected upon the arrival of each group of piglets at the farm (PT0); and final sample was collected 15 min after the arrival of each group (PT15). In groups W-10, W-15 and W-10, lactate concentrations at weaning-induced stress increased (P <.05) by almost 50% with respect to baseline levels (P <.05). At 15 min after arrival at the farm in W-10 lactate concentrations increased by approximately 60% in the piglets transported via UPR, compared to PT0 (P <.05). During weaning and the evaluation carried out immediately after transport, no significant changes in pH were observed in any of the three experimental groups. Later, however, pH decreased in group W-10 after the PT15 stage compared to the PT0 stage in the piglets transported by PR. Similar to the lactate levels, glucose concentrations in the piglets in the three age groups increased at the moment of weaning with respect to baseline levels (P <.05). However, glucose decreased in the PT0 stage vs. weaning-induced stress only in groups W-10 and W-15 under both conditions, UPR and PR (P <.05). In relation to the PT15 stage for the three groups of piglets transported over the UPR, glucose increased with respect to the PT0 stage (P<.05). These results indicate that the weaning process in piglets alters their acid base balance by increasing lactate and glucose concentrations regardless of age at weaning. This hyperlactataemia is accentuated when the animals are transported for 6 h immediately post-weaning at 10 and 15 days of age, regardless of the conditions of the roadway used. The effects were the same in 21-day-old piglets but only when they were transported on the UPR. (C) 2014 Elsevier B.V. All rights reserved.