S. Garciabelenguer et al., DIFFERENCES IN THE BIOLOGICAL STRESS RESPONSES OF 2 CATTLE BREEDS TO WALKING UP TO MOUNTAIN PASTURES IN THE PYRENEES, Veterinary research, 27(4-5), 1996, pp. 515-526
The aim of this experiment was to study the biological responses of Pi
renaica and Parda Alpina cows (2-4 years old, n = 32) and their calves
(2-4 months old, n = 32) to the physical exercise of climbing to moun
tain pastures in spring. These two breeds have a different sensitivity
to stress-induced myopathy, the Pirenaica calves being highly sensiti
ve. The animals walked 14 km with an elevation increase of 600 m, in a
pproximately 3 h. Blood samples were obtained the day before, immediat
ely after the move to the mountain pastures and the following day. The
plasma cortisol levels in Pirenaica cows were significantly higher th
an in Parda Alpina cows under basal conditions, but disappeared in lat
er samples. There were also significant differences in the hematologic
al parameters. Under basal conditions, the red blood cell counts, pack
ed cell volume, and hemoglobin content of blood were higher in Parda A
lpina than in Pirenaica cows, but calves of both breeds did not differ
. On the other hand, the calves of both breeds were more sensitive tha
n their darns to the exercise, as shown by the large increase in white
blood cell counts with a reversal of the lymphocytes:neutrophils rati
o, a consequence of cortisol secretion. In calves the largest differen
ces were observed in the muscle enzyme activity levels measured in ser
um (creatin kinase, lactic dehydrogenase, aspartate amino transferase
and alanine amino transferase), which were always higher in the Pirena
ica carves both under basal conditions and after exercise. These biolo
gical changes reflected the sensitivity of Pirenaica calves to muscula
r problems when they walk up to the pasture. it was concluded that gen
etic factors and age might play essential roles in the neuroendocrine
and metabolic adaptation to this unusual physical exercise.