School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemFinishing prime lambs using pulse stubbles, and pulse and cereal grains in the Wimmera region of Victoria( 1998)Three trials were conducted as part of this study. The first trial evaluated faba bean and chick pea stubble as feed source for the finishing of lambs. The second trial evaluated the use of barley and field peas in feed lot rations for lambs, and the final trial evaluated narbon beans and vetch as substitute grains for field peas in feed lot rations for lambs. In the first experiment one hundred and twenty six Poll Dorset x (Border Leicester x Merino) mixed sex lambs with a mean liveweight of 40.0 kg � 0.3 kg were grazed on faba bean (FB) or chick pea (CP) stubble at a stocking rate of 6.5/ha and received a supplement of 300 g/hd/day of barley (+B) or were unsupplemented (-B). There was no significant difference (P>0.05) in average daily gain (ADG) over the duration of the trial between lambs grazing faba bean and chick pea stubble, supplemented with barley or unsupplemented. Lambs supplemented with barley tended (P- 4.06) to have a lower ADG in the first fortnightly period, and had significantly lower (P<0.05) ADG in the second period. This result is supported by the observation of supplemented lambs not grazing the stubble but waiting to be fed the barley supplement. This result was reversed in the third period when supplemented lambs tended (P~.06) to have a higher ADG, and in the final period when the ADG was significantly higher (P<0.05) than the unsupplemented lambs. There was a significant correlation (P<0.01 for faba bean stubble and P<0.05 for chick pea stubble) between ADG of unsupplemented lambs and the quantity of grain residue in the stubble. In the second experiment eighty Border Leicester x Merino mixed sex lambs with a mean liveweight of 27.3 kg � 0.2 kg were fed barley (B) or barley + field peas (B+FP) (60:40) either daily at 800 g/hd/day or ad libitum for 56 days following a 14 day introductory period. Hay was provided ad libitum. There was no significant difference (P>0.05) in ADG between lambs fed the treatment rations. Lambs fed B+FP were significantly different to lambs fed barley in the following: higher carcass weight (P<0.05); fatter (P<0.05); higher dressing percentage (P<0.01); higher estimated carcass weight gain (P<0.05) and lower dry matter intake to estimated carcass weight gain ratio (P<0.05). There was no significant difference (P>0.05) in any of the measured characteristics between lambs fed restricted or lambs fed ad libitum. In the third experiment twenty four Poll Dorset x (Border Leicester x Merino) lambs with a mean liveweight of 28.8 kg � 0.45 kg were individually penned and fed ad libitum a ration of narbon beans (NB), vetch (V) or field peas (FP) mixed with wheat and formulated to 16% crude protein. Milled hay was provided separately ad libitum. There was no significant difference (P>0.05) in growth rate, carcass weight, dressing percentage, feed intake, or dry matter intake to liveweight gain ratio between lambs fed the three rations. The growth rate and feed intake of lambs fed FP was more consistent than lambs fed NB or V. Scouring was observed in lambs fed V. There was highly significant (P<0.001) separation and selection of wheat in the NB and FP based rations. Further research needs to be carried out to evaluate meat quality of lambs fed narbon beans and vetch, in particular to determine if there is any effect on flavour of the meat. The use of pulse stubbles, combined with lot feeding can form a feeding system to enable lambs to be finished in the autumn-winter period in the Wimmera region. The growth rate of lambs grazing pulse stubbles is dependent on the quantity of grain residue on the ground. The growth rate can be maintained as grain level declines by the introduction of a barley supplement. Lot feeding can be used to finish lambs when pulse stubbles have been grazed out. A combination of a cereal grain and a pulse grain formulated to 16% crude protein can be fed ad libitum. Hay can be provided separately ad libitum, or a more controlled intake of hay can be achieved by feeding a calculated amount daily.
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ItemAcute prenatal androgen treatment in sheep( 1994)The steroid environment of the cell nucleus in differentiating mammals is a major determinant of subsequent cellular function. The exogenous manipulation of this environment has resulted in permanent changes in metabolism, behaviour, reproduction, endocrinology and growth. The experiments described in this thesis suggest that an acute exposure to exogenous androgen, established as an intramuscular depot in the gravid ewe, can effect these changes. The growth responses resulting from acute prenatal androgen treatment (APAT) are similar to those reported for chronic androgenization.The undesirable side effects of androgenization, e.g. reduced birthweight, deformed external female genitalia and masculine urination posture, can be avoided with APAT. The literature and the experimental data indicate that mammalian development is strongly influenced by tissue steroid status. Furthermore, the literature and the experimental data suggest that both the timing and duration of the modification of mammalian developmental steroid status (MDSS) affect the response of ovine tissues to androgens. Some of the observed responses appear refractory in nature. The periods of sensitivity to MDSS manipulation differ between tissues and between species. MDSS manipulation via APAT is capable of effecting changes to tissues not normally considered sexually dimorphic, including the ovine pancreas, liver, brain, kidney, bone and wool follicle.
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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.
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ItemCowpea and navy bean seeds as supplements for sheep( 1992)This study was conducted to determine the feeding value of cowpea and navy bean seeds as supplements for growing sheep fed equal amounts of oaten chaff and barley straw (basal diet) and the digestibility of the basal diet when cowpea and navy bean seeds were used. Thirty-six sheep were used both in period 1 and period 2 of the feeding trial (Experiment 1), randomly assigned to no supplement, 0.5, 1.0 and 2.0% LW of lupin, cowpea and navy bean, and 2.0% LW of lupin and navy bean plus antibiotics, and twenty-four sheep were used in the digestibility trial (Experiment 2) using 1.0% LW of lupin, cowpea and navy bean and no supplement. Results indicated that navy bean seeds and cowpea seeds when used as supplements should be limited by up to 0.5 and 1.0% LW respectively for sheep fed equal amounts of oaten chaff and barley straw.
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ItemCytogenetic sex determination of embryos( 1990)The purpose of the research presented in this thesis was to establish a rapid method to allow the cytogenetic determination of sex in sheep embryos. A simplified air-drying technique to allow cytogenetic sex determination initially established in mouse embryos. These techniques were then applied to sheep embryos. The techniques involved treating embryos with three types of fixatives :- fixing solution, softening solution and drying solution. Methanol : glacial acetic acid
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ItemIntake and utilization of a barley supplement treated with virginiamycin by gestating and lactating ewes( 1991)A pen feeding study was conducted to evaluate the influence of virginiamycin (40 g virginiamycin/tonne barley ) on the production of pregnant and lactating ewes fed barley supplement. Twelve single and sixteen twin-bearing ewes were randomly allocated to one . of 3 groups to receive either lupins, barley or barley plus virginiamycin (BVM), fed for 3 weeks before and 3 weeks after lambing. During late pregnancy, feed intakes in ewes carrying twins were not altered by treatments. Mean liveweights at parturition of the barley-supplemented 'ewes. were below than those of the other groups (p=0.14). Feed conversion efficiency was significantly improved (p=0.05) in the lupin and BVM groups as compared to the barley supplemented ewes. The condition score of the ewes was not improved by supplementation and type of supplement had no effects on body condition score loss. Mean retention time of Cr-hay in the GI tract was increased (p<0.05) by supplementation with virginiamycin treated grain. However the dry matter digestibility on the BVM diet was not improved (p<0.05) as compared to the lupin supplemented ewes. The performance of ewes carrying singles was generally unaffected by treatment (p>0.1). The. exception occurred during lactation, where the barley-supplemented ewes lost more weight than the other groups (p<0.05). Differences in the mean birth weight of twin lambs were significant (p=0.05) while those of lambs born as singles was not significant. Twin lambs from ewes fed barley showed significantly higher mortality (p<0.01) than lambs born to ewes in lupin and BVM groups. However , no single born lambs in any group died from birth to 42 days of age. No significant differences were found between total milk yields of ewes nursing either twin or single lambs. The yield of milk fat from ewes nursing twins in lupin group was significantly higher (p<0.05) at day 20 of lactation than the other groups. The results suggest that lupin grain was not superior to barley grain plus virginiamycin as a supplement for gestating and lactating ewes carrying twin lambs fed hay as a basal diet. However, on the basis of cost, barley plus virginiamycin would generally be prefered.
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