A study of diurnal changes in cortisol and glucose levels and fdpa activity in foals during the first 13 weeks of life and in their lactating mothers

Changes of circulating β-endorphin, adrenocorticotrophin and cortisol concentrations during growth and rearing in Thoroughbred foals

“…In addition, slight variations could be ascribed to differences in techniques and some differences may also be explained by physical and psychological factors. The comparison of results obtained in this study with published data reported for horses did not reveal any large discrepancies for circulating β-endorphin levels (Hamra et al, 1993;Hydbring et al, 1996;Lebelt et al, 1998;McGreevy and Nicol, 1998;Mehl et al, 1999;Pell and McGreevy, 1999), ACTH (Orth et al, 1982;Card and Manning, 2000) and cortisol (Asa et al, 1983;Gill et al, 1985;Flisińska-Bojanowska et al, 1989;Ferlazzo and Fazio, 1997; Card and Table 3 Circulating β-endorphin, ACTH and cortisol concentrations (Means ± S.D.) during growth and rearing in colts and fillies.…”

“…In addition, diurnal cortisol rhythms were found to already occur in the first 2 months of foal life, with the acrophase at 08:30 a.m. (Komosa et al, 1990) and at 3, 7 and 11 weeks of foal life (Flisińska-Bojanowska et al, 1989). A circadian cortisol rhythm exists in horses in the absence of any known cues imposed by humans.…”

Circadian pattern of hepatosomatic index, liver glycogen and lipid content, plasma non-esterified fatty acid, glucose, T3, T4, growth hormone and cortisol concentrations in Oncorhynchus mykiss held under different photoperiod regimes and fed using demand-feeders

“…It is possible that the peaks reflect the gluconeogenic effects of post-prandial elevations in plasma cortisol concentrations. Similar feeding-entrained increases of glucose are known in some mammals (e.g., Armstrong 1980;Saito et al 1989), although it is not found in browsing mammals that feed over long periods of the day (Flisinska-Bojanowska et al 1989).…”

State of the art on daily rhythms of physiology and behaviour in horses

“…Circadian rhythms of glucose and insulin have been reported in horses (Evans et al 1974), but it was shown that these rhythms are lost when the animals are fasted (Stull and Rodiek 1987), and modified when the animals are subjected to different feeding regimes (Piccione et al 2008b). In foals there is no circadian rhythm of glucose (Flisin´ska-Bojanowska et al 1989), probably due to the periodic suckling during the day and night that does not allow the blood glucose concentration to reach a daily peak. Circadian rhythms of cortisol have been reported in horses with highest levels in the morning and the lowest in the evening (Hoffsis et al 1970;Evans et al 1974;Larsson et al 1979); in foals a diurnal rhythm of cortisol level was found as early as in the first week of life, its acrophase was observed at 04:30 and tends to reach adult one at 7-11 weeks of life (Flisin´ska-Bojanowska et al 1989.…”

“…In foals there is no circadian rhythm of glucose (Flisin´ska-Bojanowska et al 1989), probably due to the periodic suckling during the day and night that does not allow the blood glucose concentration to reach a daily peak. Circadian rhythms of cortisol have been reported in horses with highest levels in the morning and the lowest in the evening (Hoffsis et al 1970;Evans et al 1974;Larsson et al 1979); in foals a diurnal rhythm of cortisol level was found as early as in the first week of life, its acrophase was observed at 04:30 and tends to reach adult one at 7-11 weeks of life (Flisin´ska-Bojanowska et al 1989. Gender differences of peripheral steroid hormone concentration were observed in females when compared to males and geldings (Fletcher et al 2000).…”