Date Full Report Received01/05/2004
Date Abstract Report Received07/26/2006
InvestigationInstitution: University of Manitoba
Primary Investigator: Nora J. Lewis, Robert J. Berry
Funded ByNational Pork Board
Assessment of the effects of the season of transport on the performance of early-weaned piglets.
Can. J. Anim. Sci. 2005. 85:449-454.
Effects of season on the behaviour of early-weaned piglets during and immediately following transport.
App. Anim. Behav. Sci. 2006. 100:182-192.
Impact of transport: Behavior during transport provides us with indicators of the immediate problems faced by piglets during transport and the coping strategies of the piglets. We can look at each behavior and assess the reasons underlying the change in frequency in relationship to the transport environment. This provides us with a method for judging the impact of transportation. Establishment of the dominance hierarchy, as indicated by fighting, was considerably delayed during transport indicating some stress associated with early transport, probably related to weaning and the new environment of the truck. Behavior changed markedly after 12 h of transport. Active behaviors such as standing and sitting decreased while resting increased indicative of fatigue. However since the changes in standing and resting were most noticeable during winter and fall some of the increased resting may have been associated with cold temperatures. Ear and rectal temperatures also began to drop after 12 h of transport. At this time outside temperatures were also dropping. Piglets may have reduced other activities and rested in order to conserve body temperature.
Behavior post-transport also provides us with information to assess the stress of transport. Piglets which start to feed early, become hydrated rapidly and show normal behavior patterns can be said to have recovered well from transport and weaning. Behaviors which increase during long transportation or which are more prevalent in transported than non-transported piglets are usually indicative of higher transport stress. Such behaviors include resting, associated with fatigue and drinking, associated with dehydration. In this study standing was observed less frequently and resting was more common, in transported piglets, indicating fatigue following transport. This was most apparent following winter transport (3 d) but was also observed following summer transport (2 d). Feeding was observed more frequently in piglets transported for 12 or 24 h, reflecting an increased motivation to feed and possibly an increase in piglet age at the time of introduction to feed. Transported piglets drank more often, although this was not significantly different until piglets had been transported for 24 h.
There was also a strong seasonal pattern in which the behavior of piglets during the fall differed significantly from behavior in winter and summer. Standing was less frequently observed and sitting was more frequently observed in the fall, indicating a higher stress level in this season. Higher drinking frequencies were extended into day 2 in the fall indicating that the piglets were not able to meet their needs on day 1, unlike piglets observed in other seasons. Transported piglets, irrespective of duration of transport and season showed some behaviors associated with transport. Standing was less frequently observed while sitting, resting (day 1) and drinking (day 1) were more frequently observed in transported piglets and can be associated with transport stressors.
Impact of winter transport without supplemental heat: The cold temperatures during winter transport changed piglet behavior and physiology, encouraging lower levels of activity and decreases in ear and rectal temperature. These changes were most apparent after 12 h of transport. Higher levels of resting, indicative of fatigue, were noted for 3 days post-transport. Average daily gain (post recovery) was lowest in winter and 76 % of “poor doers” (less than weaning weight after 7 days) were observed in the winter. Transported pigs irrespective of season show some signs of stress and it is important to determine which stressors are most important in each season in order to provide an environment favorable to high welfare and short growth checks but this is especially important for winter transport where production and therefore welfare is compromised up to 14 days after transport.
Performance Measures: Growth curves were computer generated based on daily body weights. These growth curves were used to calculate 4 important production variables: 1) the lowest body weight, 2) the time at which this lowest weight was reached, 3) the time at which the weaning weight was regained (Day of Recovery) and 4) average daily gain from the day of recovery to 14 d post weaning. This array of variables provided a comprehensive assessment of early post weaning growth. The time to reach the lowest body weight and the lowest weight reached were a measure of how much of the piglets reserves were used during the weaning process and to compensate for losses during transport. The Day of recovery reflects the ability of the piglet to recover from these losses and the post recovery average daily gain reflects longer term affects on growth and performance. On average piglets lost 0.45 kg body weight over 2.4 days. The Day of Recovery averaged 3.7 days and average daily gain from Day of Recovery to 14 d was 0.38 kg. Lower average daily gains post recovery in piglets transported in winter indicate that these piglets have a longer recovery period, at least 14 days, than would have been indicated by the other production measures.