[Does the supply of magnesium affect the feed intake in ruminants?].

The magnesium balance is in a state of equilibrium in dairy cattle when the daily excretion of Mg in the urine is a least 2.5 g. (= 100 mM). When the daily urinary output is 25 l, this is equivalent to a concentration of at least 4 mM (= 100 mg/l). The production of milk was inadequate on a number of dairy farms, which was associated with loss of appetite of the cows. The concentration of Mg in the urine of various cows was found to be too low on these farms. When additional magnesium was supplied, the feed intake was restored within a few days and the milk production also increased. The finding that an inadequate supply of Mg may have a negative effect on the feed intake was supported by some findings reported in the literature.