Influence of subclinical magnesium deficiency in the antenatal period on mineral and energy management during early lactation

Abstract

Magnesium (Mg) is an activator of more than three hundred enzymes and a cofactor in the synthesis and release of hormones. Currently, magnesium deficiency occurs in dairy cows most frequently in a subclinical form, with symptoms limited to decreased appetite and decreased milk yield. The study included 50 cows, which were diagnosed with magnesium deficiency in the antenatal period. In group I (n = 25), increased supplementation was not applied; in group II (n = 25) the intake of Mg was increased by a 7% magnesium supplement. The control group consisted of 25 healthy cows. Blood samples for tests were taken 2 weeks prepartum, as well as 1 and 2 weeks postnatally, to determine the concentrations of: total magnesium (Mg), total calcium (Ca), inorganic phosphorus (Pn), copper (Cu), zinc (Zn), total bilirubin (tB), total protein (TP), glucose (Glu) and cholesterol (TC), as well as the activity of aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGTP). In group I, the highest number of cows with decreased appetite and postpartum weakness were identified, which exhibited the lowest rate of increase in milk production and a significantly lower mean blood calcium concentration. The highest mean concentrations of tB and decreases TC and Glu concentrations were also recorded in this group. Our studies confirm the need to monitor mineral deficiencies not only during lactation, but also before delivery, as well as the effectiveness of an appropriate prophylactic regimen based on oral administration of magnesium preparations which cause the least biochemical changes in blood. The lack of supplementation in the subclinical form of antenatal Mg deficiency may cause severe gastrointestinal and reproductive disorders in the postnatal period.