Biology Reference
In-Depth Information
(Selye
1976
). The wide range of AT during both transports activated adaptation in
the calves that was controlled by efficient thermoregulation, assuring physiological
homeothermia without the appearance of thermic stress. Within the tested thermic
range, thermoregulation functioned properly, particularly in winter conditions. In
summer, only AT near 30
C reduced the function of the thermoregulatory center
with the concomitant appearance of clinical signs. Comparing summer and winter
temperatures, a moderate linear correlation between AT and RT was observed,
indicating that RT kept itself almost steady. The decrease in BW during the
journeys could be due to fluid losses that were greater in the summer. In comparison
with BW at the Polish farms, the weight loss recorded before departure could be
ascribed to massive feeding given by the Polish farmers to achieve a greater sale
price. Even though the calves did not show, during either transport, any clinical
signs and only slight dehydration, it is important to prevent possible electrolyte and
mineral losses by early supplementation during the first hours after arrival. Etho-
logical anomalies, signals of psychophysical discomfort (stereotypes), were seen
only at limited times without appearing obsessive and/or maniacal. During both
transports, at the first stop, lying-down calves stood up within 3-4 min. During the
journey, they exhibited cross-licking, cross-sucking, and self-grooming. After
departure and for the whole length of the transport, the calves placed themselves
with their cranial/caudal axis perpendicular to the driving direction. The animals
showed discomfort during loading and unloading; furthermore, less psycho-physical
discomfort was observed in the calves placed in the lower boxes of the truck
compared with the upper ones. The changes found in the ECGs were critical during
loading and unloading with sinusal tachycardia episodes. It is necessary to
extend the data set of animals to better understand the causes of these HR
increases. Individual animal sensitivities and subjective evaluation of the events
make the animals vulnerable to the stress (Locatelli
1989
), making it difficult to
distinguish between discomfort and stress and to estimate the threshold values of
stress. As the animal's response is determined by complex interactions between
genetic factors and experiences, it is impossible to generalize behaviors within
the same or different breeds and species regarding various stressors. After the
20-h journey, the calves were not unloaded into the lairage cattle shed, but were
transported for 2 additional hours to the destination farm. The handling of the
animals during unloading and reloading in the lairage cattle shed causes not
only further detrimental muscular strain but also an extension of the journey that
leads to a marked change in homeostasis with a delayed return of biochemical
blood parameters to normal (Bernardini et al.
2001
). The stressors cannot be
avoided, but as reported by Selye (
1976
), it is not necessary to completely
remove the sources of stress, but instead to optimize them to make them
tolerable and useful for survival and the execution of activities that the animals
encounter. It is indispensable to execute a strategy that allows the farmers to
work effectively within an international context and is characterized by increas-
ing competition with new productive balances in light of national and commu-
nity regulations.
