Metabolic and hormonal profiles of potentiated cold stress in lambs during early postnatal period

Abstract

Metabolic and hormonal blood profiles under the influence of cold stress potentiated by a 20-minute cold water shower were studied in 2- to 3-day old lambs of Merinolandschaf (Group I, n = 8) and Romney Marsh (Group II, n = 11) breeds. e metabolic profile included parameters such as total proteins (TP), urea, glucose, nonesterified fatty acids (NEFA) and triacylglycerols (TGL). e concentrations of NEFA and TGL were found to increase significantly ( P < 0.05) in lambs of Merinolandschaf breed following the potentiated cold stress. Compar- ing the breeds subjected to the potentiated cold stress, there were no significant differences in the metabolic profile. e hormonal profile was evaluated using cortisol, triiodothyronine (T 3 ) and thyroxine (T 4 ). A significant increase (P < 0.05) in both cortisol and T 3, T 4 levels was observed in lambs of both breeds following the potentiated cold stress. Comparing the breeds subjected to the potentiated cold stress, the level of cortisol was significantly higher in the Romney Marsh breed (P < 0.05), while, on the other hand, the levels of T 3 and T 4 were significantly higher (P < 0.05) in lambs of Merinolandschaf breed. e stronger adrenocortical response of Romney Marsh breed was probably due to higher sensitivity of lambs to emotional components of stress evidenced by more intensive changes of behaviour. e weaker thyroidal response of lambs of Romney Marsh breed as compared to the Merinolandschaf ones could also be associated with a higher level of physical thermoregulation (i.e. better thermo-isolation qualities of their fleece). e activation of the thyrotropic axis together with shivering thermogenesis resulted in a significant increase in the rectal temperature in lambs of both breeds immediately after the potentiation of cold stress.