An analysis of cattle live-weight changes on tropical grass pasture during the dry and early wet seasons in northern Australia: 2. Relations to trends in the pasture, diet and grazing behaviour

R. L. McCown, R. W. McLean
1983 Journal of Agricultural Science  
Cattle grazing buffel grass pastures during the dry season at Katherine lose large amounts of live weight during a short period following first rain. In Part 1 we showed that these losses were due mainly to reduction in gut contents. Part 2 examines the changes in pasture, diet and grazing behaviour to assess the probable change in nutritional status of cattle following rain. During the dry season the most valuable pasture component, green leaf, was very scarce and had a nitrogen concentration
more » ... ogen concentration of about 1 %. Diets of oesophageally-fistulated cattle contained less than 0-5% N. Shortly after first rain diet N doubled owing both to rapidly increasing amounts of green leaf and to the increase in N concentration in young leaf to over 3 %. Although intake was not measured, literature is cited to show that this increase in dietary N would be expected to increase rumen digestion rates with a resultant marked increase in D.M. intake and a reduction in gut contents. Although availability of high quality herbage increased very rapidly following first rain, a period of increased nutritional stress immediately following rain could not be ruled out. However, any such decline in nutrition appears to be short-lived.
doi:10.1017/s0021859600036327 fatcat:ahlocpp6gfdr5e5g2njjafuuwe