Med. Weter. 72 (4), 231-236, 2016

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Dratwa-Chałupnik A., Ożgo M., Michałek K.
Water and electrolyte management in calves before and after excessive lactose administration
The aim of the study was to assess the dynamics of changes in ANP, AVP, and ALDO before and after the administration of lactose (a causative agent of diarrhea) and to evaluate the ability of the kidneys to regulate isotonicity by analyzing the concentrations of the major blood plasma electrolytes and osmotic pressure before and after lactose administration. The experiment was carried out on 8 Polish Holstein-Friesian calves of the Black-and-White variety during the second and third weeks of life. Animals were fed with a milk replacer twice a day in an amount of 10% of body weight. Monohydrate lactose in an amount of 1g kg-1 of body weight was added twice to the milk replacer. The average concentration of atrial natriuretic peptide in the blood plasma of calves was low during the second week of life, but increased in the third week. The levels of plasma ALDO and AVP before the administration of lactose was higher in two-week-old calves than it was in three-week-old calves. The concentration of vasopressin in two- and three-week-old calves decreased in successive days of the experiment. Only in two-week-old calves a statistically significant increase in the concentration of aldosterone was noted 60 h after lactose administration. The concentrations of sodium, potassium, and chloride in blood plasma before the administration of lactose were higher in three-week-old calves than they were in two-week-old calves. The administration of lactose resulted in a significant increase in the concentrations of sodium and potassium in the blood plasma of two-week-old calves and caused a significant increase in the concentration of chloride in three-week-old calves. During the first weeks of life, the activity of factors regulating renal functions, in conjunction with relatively stable blood levels of the main electrolytes and the osmotic pressure of blood plasma, indicates a functional maturity of kidneys in healthy calves and in calves manifesting light symptoms of diarrhea. These results also suggest that the mechanisms involved in the regulation of water and electrolyte homeostasis in these calves are efficient.
Key words: ANP, ALDO, AVP, electrolyte.