The aim of this study was to evaluate the hypothalamic-
pituitary-adrenal (HPA) axis activity of Holstein-
Friesian and crossbreed F1 heifers by analysis of the
cortisol concentrations in hair samples. Cortisol, the
primary hormone of the HPA axis, is the biological endpoint
for the investigation of the HPA response. The
study was conducted on 290 prepubertal heifers; 142
heifers were pure Holstein-Friesian and 148 were crossbreed
F1 heifers obtained from the 3-way rotational
system with Swedish Red and MontbeĢliarde breeds.
Extraction was performed on the hair using methanol,
and cortisol concentrations were determined by a radioimmunoassay
method. Cortisol concentrations measured
in regrown hair of crossbreed F1 heifers were significantly
lower than those in hair of Holstein-Friesian
heifers. This result helps us to better understand the
differences in HPA activity and allostatic load between
Holstein-Friesian and crossbreed F1 heifers and allows
us to better assess the adaptability of these animals
to the environment and the importance of crossbreed
traits for profitability in dairy farming.
