Effect of diet and physiological state on recycling of urea in Merino ewes

The recycling of urea to the rumen was studied in Merino ewes during differentp hysiologicals tates using radioactivet racers. The results showed that although the proportion of urea recycled differed, similar amounts were recycled in dry and pregnant sheep over a wide range of N intake. Urea recycling increased significantly during lactation on all diets when compared with non-lactatings heep.T hus, factors other than simple diffusion of urea control urea recycling in sheep although the control mechanisms remain undefined.Die hersirkulasiev an ureum na die grootpensi s ondersoekb y Merino ooie tydens verskillendef isiologieset oestanded eur gebruik te maak van radio-aktiewem erkers.D ie resultatet oon dat hoewel die verhoudingu reum wat gehersirkuleeirs , verskil, is dieselfdeh oeveelhedeg ehersirkuleeirn dro€ en dragtige skape oor 'n wye reeksv an N inname.H ersirkulasiev an ureum het betekenisvotl oegeneemt ydens laktasieo p alle di€te, in vergelykingm et nie-lakterendes kape.D aar is dus ander faktore as eenvoudiged iffusie van ureum wat die hersirkulasiev an ureum in skape beheer, alhoewel die beheermeganismes ongedefinieerb ly.Keywords: Urea entry, urea recycling, pregnancy, lactation, ewes, nitrogen intak