School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe relative value of tagasaste and lucerne as supplementary feeds for sheep( 1993)Chamaecytisus palmensis (Tagasaste) is a leguminous perennial shrub which grows well in a range of climatic zones. Tagasaste was introduced from the Canary Islands to Australia in 1879 and a number of farmers are growing the shrub for fodder production and soil conservation. The most economical means of utilizing tagasaste in Australia appears to be direct grazing by sheep. This thesis reports on a study of tagasaste and lucerne as a supplementary summer feed for sheep in the Strathfieldsaye Research Station, East Gippsland, Victoria. The purpose of the present study was to investigate the relative value of feeding tagasaste and lucerne (Medicago sativa) as a supplementary feed for sheep during summer. Growth performance of sheep, dry matter consumed and the chemical composition of feeds were examined over the four months of the experimental period. The 240 two year old Merino sheep were divided into 12 groups for grazing eight plots of tagasaste and four plots of lucerne as a supplement to summer pasture. Each plot had been fenced into four or six subplots for tagasaste or lucerne respectively, to allow stock to be rotated in four months. The estimation of the dry matter consumed in each subplot was done by selecting 50 sample quadrats before and after grazing for each experimental month. The mean liveweight gain for all sheep in the lucerne plots (11.3 kg/head) was not significantly different from tagasaste (10.6 kg/head) at the end of the experiment. The mean total change in standing dry matter due to grazing in the tagasaste treatment (5360 kg/ha) over the four months was greater than for the lucerne treatment (3384 kg/ha). The overall daily growth efficiency over the daily dry matter (LW (g)/DM (g)) eaten by sheep in tagasaste was 0.20% and 0.34% for lucerne over the experimental period. In both treatments the pattern of pasture dry matter consumption did not resemble the pattern of liveweight gain. The digestibility and total nitrogen content of feed types were not significantly different between trial months. However, the leaf part of tagasaste had significantly greater values than other feed types during the trial although lucerne leaf was not measured. During the trial there was no loss of liveweight in sheep fed tagasaste or lucerne as a supplement. A second experiment indicated that tagasaste regrowth after grazing was significantly better in lightly grazed plots than in heavily grazed plots suggesting that farmers remove stock before all leaf has been eaten. In conclusion, the results of this study suggest that there is scope for the summer grazing tagasaste as a supplement to dry pasture however lucerne remains a better feed than tagasaste on this site. The high quality of tagasaste foliage (leaf) and low rate of liveweight gain of the experimental sheep suggest that further study is necessary to identify the cause of low stock performance.