Abstract
The effect of high and low selective grazing by Holstein steer calves on number of dung patches in grazing pasture, consumption, nutritive value and digestibility of dry matter ingested ; and changes in body parts and weight, were studied. A system of rotational grazing was followed ; one group steers was grazed about 30% (rapid rotational grazing-R system) and a second group about 70% (slow rotational grazing-S system) of the grazeable herbage in orchardgrass dominant pasture. Steers in R system consume the upper parts of herbage mainly, but steers in S system consume the whole herbage from upper to bottom of it. Dung patches in the pasture disappeared at one month after occurrence of its in the both grazing systems, and there were no difference of number of dung patches between the both grazing systems. There were no difference of DCP and TDN intake of steers between the both grazing systems in spring and autumn. But in summer, DCP and TDN intake of steers in R system were more than that in S system, especially DCP. There was no difference of digestibility of herbage ingested between the both grazing systems in spring and autumn. But in summer, the digestibility of herbage ingested in R system was higher than that in S system. This difference was caused by that the digestibility in R system did not almost change during seasons, but the digestibility in summer became lower than that in spring and autumn in S system. The growth of all body parts of steers in R system were more than that in S system, and the difference of body length of steers was much markedly. There was no difference of DG between the both systems in spring and autumn, but in summer, DG in R system was more than that in S system. The change of DG of steers corresponded closely with the nutrient intake, especially in summer.
