Dynamics of Calcaemia, Phosphoraemia and Magnesaemia at Different Prepartal Intakes of Calcium in Dairy Cows

Abstract

The objective of this study was to compare the efficiency of high and low Ca intake in cows with analytically defined levels of calcaemia, phosphoraemia and magnesaemia in the prepartal period, on their postpartal changes important for the diagnosis of postpartal diseases. In dairy cows (Czech Pied cattle) receiving a winter feed ration, the prepartal intake of Ca was adjusted from day 241 of pregnancy to 80% in group A (n = 15) and to 160% of the standard in group B (n = 9). In both groups the concentrations of Ca, P and Mg in blood serum were measured at the beginning of experimental diets, on day 12 before the expected parturition, and on days 1, 2, 3 and 4 after parturition. At the beginning of the experiment (42 days before parturition) the value of calcaemia was 1.82 ± 0.10 mmol l-1, phosphoraemia 1.61 ± 0.37 mmol l-1 and magnesaemia 0.74 ± 0.6 mmol l-1 of blood serum. After the 30-day feeding of experimental diet (day 12 before the expected parturition) higher hypocalcaemia was recorded in group A persisting to day 3 post partum. Phosphoraemia and magnesaemia were at the lower limit of reference values only from day 12 before the expected parturition to day 4 post partum. In group A three cows became recumbent until day 3 post partum with a decrease in magnesaemia below 0.5 mmol l-1. Phosphoraemia and magnesaemia were at the lower limit of reference values only from day 12 before the expected parturition to day 4 post partum. In group A three cows became downed until day 3 post partum with a decrease in magnesaemia below 0.5 mmol l-1. In group B with 160% intake of Ca, 12 days before the expected parturition calcaemia amounted to 2.20 ± 0.27 mmol l-1 and hypocalcaemia ranging from 1.60 ± 0.45 to 1.80 ± 0.26 mmol l-1 of blood serum persisted from day 1 to day 4 post partum. The average level of phosphoraemia in group B was maintained above 1.80 mmol l-1 and magnesaemia was within the range of 0.93 - 1.21 mmol l-1 of blood serum. The results of the nutrition experiment document that for the prepartal adjustment of Ca intake aimed at a reduction in the incidence of the postpartal downer cow syndrome, it is necessary to determine calcaemia, phosphoraemia and magnesaemia in late-pregnant cows. In hypocalcaemia, hypophosphoraemia and especially hypomagnesaemia the prepartal diet with 80% coverage of Ca need leads to a higher risk of the downer cow syndrome accompanied by higher hypomagnesaemia.