The effect transport and space allowance on the physiology of breeding age gilts

Long duration transport of pigs is an important welfare issue world-wide. Current transportation legislation in the United States dictates that animals cannot be transported over 28 h without being rested and given food and water; however there is limited information available on the acute physiological effects of long distance transport on pigs. The objective of this study was to evaluate the effects of a 6, 12, 18, 24, or 30 h transport period on the physiology of breeding age gilts. Eight weight matched gilts were allocated to one of 15 treatment groups. Treatments included: Gilts that remained in their home pen for 6, 12, 18, 24, or 30 h (CON); Gilts that were transported for 6, 12, 18, 24, or 30 h at the transport quality assurance guidelines specified space allowance (TQA); or Gilts that were transported for 6, 12, 18, 24, or 30 h at the TQA specified space allowance plus 20% extra space (TQA+). Every 6 h, pigs in one pair of compartments (TQA and TQA+) were removed from the trailer (after a 6, 12, 18, 24, or 30 h transport period). Blood samples and body weights were collected from gilts and their respective controls before and after transport. The granulocyte to lymphocyte ratio was greater (P < 0.005) in TQA and TQA+ gilts transported for 6 h compared with controls. The percentage of lymphocyte and granulocytes, platelet counts, hemoglobin, and hematocrit concentrations were affected (P < 0.05) by transport and the duration of transport. Total white blood cell and lymphocyte counts were lower (P < 0.001) and albumin, glucose, total bilirubin, and total protein concentrations were greater (P < 0.05) in TQA and TQA+ compared to controls regardless of transport period. Creatine kinase concentrations were greater (P < 0.05) in TQA compared with controls. Percent body weight was decreased (P < 0.05) in TQA and TQA+ gilts after a 6, 12, 18, 24, and 30 h transport period compared with controls. Physiological measures of acute stress were observed in transported gilts (TQA and TQA+) after a 6 h transport period, but then returned to similar levels as non-transported control gilts. Physiological measures of dehydration and muscle breakdown were observed in gilts after transport, regardless of transport duration. Overall, these data indicate that gilts transported for a period of up to 30 h experience acute stress and changes in homeostasis probably due to dehydration, food deprivation, and transport.