The effects of slow-release zinc-urea complexes (ZnU), urea-impregnated zeolite (UZ) and zinc-urea-impregnated zeolite (ZnUZ) on the performance of yearling Bali bulls were assessed using 20 Bali bulls (145.3 ± 2.5 kg bodyweight (BW)), which were allocated to five treatments and four replications in a completely randomized design. The treatments were: Diets supplemented with no urea (NU) and with urea (U), ZnU, UZ and ZnUZ. The results of the in vivo study revealed that both ZnU and UZ might replace urea effectively by increasing feed intake. Moreover, substituting urea with ZnU, UZ or ZnUZ increased crude protein total tract apparent digestibility whereas ZnU or UZ replacing urea, improved fibre total tract apparent digestibility. Furthermore, inclusion of UZ in the diet improved live weight gain and feed efficiency in Bali bulls above that of the U and NU diets. Thus, the inclusion of ZnUZ in rice straw-based diets showed slow-release urea had positive impacts on feed intake and nutrient digestibility, and increased the efficiency of feed utilization in Bali bulls.
"Experientia docet" - Experience is the best teacher