[Reactions of dairy cows to ACTH administration and ingestion of liquid feed at different age points before and in the course of rearing with automatic milk feeding--plasma cortisol, saliva cortisol, hematologic, metabolic variables and heart rate].

On dairy calves (totally 35 animals; 14 male; 21 female) measurements of rectal temperature, heart rate and blood values (acid-base balance, Hb, Hk, MCHC, gas content and gas pressure, hemoglobin derivatives, cortisol, total protein, albumin, blood urea, creatinine, glucose, lactate, Ca, Mg, P, Fe) and of salivary cortisol were done before and after i.v. ACTH application and liquid feed intake at 5, 15, 40 and 60 days of life age. Mean values of P-cortisol, S-cortisol, heart rate and COHb were elevated and those of total protein, albumin, Mg, Hb, Hk, O2CAP were decreased after i.v. ACTH and feed intake. Mean glucose and P concentration changed differently in younger and older calves after ACTH and liquid feed intake. Changes of Ca and Fe concentration were not significant at all age points. Effects of gender could be found for cortisol, O2CONT, MCHC, total protein, creatinine, lactate, Mg, and Ca at some age points. Initial P-cortisol levels were higher at 5 and 15 days than at 40 and 60 days of life, the levels after stimulation were higher at 5 days than at 15, 40 and 60 days. Initial levels of S-cortisol were significantly different between all age points, the levels after stimulation were not different. Female calves had significantly greater P-cortisol values at 40 and 60 days as male calves and at 40 days greater S-cortisol values too. Significant correlations between P-cortisol and S-cortisol could be found before stimulation (5 days: r = 0.626; 15 days: r = 0.366; 60 days: r = 0.357) not thereafter. All measures except P-cortisol, S-cortisol, O2SAT, and HHb had significant correlations before and after ACTH and liquid feed intake indicating great interindividual variation and individual specificity of reaction within this growth period. Results were discussed under the viewpoint of reactivity of adrenocortex and steroid distribution concerning organ specific effects of steroids in calves.