Endogenous fecal Mg excretion, Mg digestibility and Mg content of various organs in sheep with different Mg uptake
Meyer, H.; Peters, E.; Scholz, H.
Deutsche Tierärztliche Wochenschrift 80(7): 160-164
1973
ISSN/ISBN: 0341-6593 PMID: 4574079 Document Number: 64010
In 3 trials with 25 male sheep 6 to 12 months old and weighing 40 to 50 kg the basal diet was low in Mg, providing about 143 mg daily, and 2 diets were supplemented with MgO 2 or 15 g making the daily intakes of Mg 1362 and 9267 mg. There was a close positive correlation (r = 0.98) of Mg in faeces to intake and endogenous faecal Mg calculated including and excluding the values for the highest intake was 2.50 and 2.74 mg/kg bodyweight, respectively. Apparent digestibility of Mg from the smaller and larger supplements was 48.5 and 49.5% and true digestibility allowing an endogenous output of 2.7 mg/kg was 52.4, 55.4 and 50.9%, the first value with no supplement. Almost no Mg appeared in urine when none was added to the diet but output with the 2 supplements was 430 and 2400 mg/day; excretion by the kidney fell when Mg in blood fell below 2 mg/100 ml and almost ceased when that in blood reached 1.6 mg/100 ml. The tissue most affected by the differences in Mg content was bone, the mean Mg content in bone ash ranging from 0.51 to 0.74%. The highest Mg intake led to an increase of water intake and a high water content of faeces. Digestibility of Na and K was not affected.