EFFECTS OF EXCESSIVE MAGNESIUM AMOUNTS AND FAT AND OIL ADDITION ON MAGNESIUM, CALCIUM AND PHOSPHORUS BALANCE IN RUMINANTS

Metabolic experiments were conducted on young bulls at the live weight of 225 kg. The effect of emissions added to model feed rations consis ting of corn silage, alfalfa hay, barley greats, wheal greats and feed ing salt was investigated as exerted on Ca, P and Mg balance in young bulls, and possibilities of eliminating negative Mg effects by use of waste fat and rapeseed oil were also studied. Mg uptake by animals was five times higher in comparison with recommended rations. Mg : Ca rat io was 34 : 1. Excessive applications of Mg in feed resulted in its hi gher output (P < 0.01) in urine and excrements. Mg digestibility expre ssed as per cent of Mg uptake was not related to the amount of ingeste d Mg. The addition of waste fat and rapeseed oil to feed rations did n ot reduce Mg resorption from the digestive tract of animals. The exces sive amounts of Mg did not influence Ca balance but they induced highe r P output in urine and excrements. The addition of waste fat and rape seed oil to feeds had positive effects on Ca and P balance while mainl y rapeseed oil had a significant effect on the level of P retention fr om P digested in the animal organism.