School of Agriculture, Food and Ecosystem Sciences - Theses
Permanent URI for this collection
Search Results
1 - 10 of 64
-
ItemA study of the effects of high stocking rates on the production of perennial pasture and its utilization by dairy cattle( 1973)The work in this thesis consists of a study of the effects of increasing the stocking rate from 2.2 to 3.2 cows per hectare on the production of dairy cattle and perennial pastures from 1966-70. (a) Milk production per cow was significantly reduced (P < 0.05) by the increase in.:stocking rate with the exception of the first year. (b) The yield of milk and milk components per hectare was increased (P< 0.05) by the increase in stocking rate except for 1968-69 when a drought occurred and the increases were not large enough in most components to attain significance (P)00.05). The yield of nitrogen in milk per hectare was significantly increased (p<0.05) in all years with stocking rate. (c) There was a tendency for the high stocking rate to lower the percentage of all components in milk with the exception of nitrogen which remained unaltered. However significant differences were not recorded consistently in any one component over the four lactations studied. (d) No significant differences (p>0.05) in seasonal or annual net pasture production were recorded between stocking rates. (e) The increase in stocking rate caused significant increases (1).<0.01) in grazing pressure, reductions in pasture availability (P<0.01) and higher contents of crude protein (1).<0.01) in pasture excepting spring and on two occasions in winter. (f) Estimates of feed intake at the higher stocking rate showed a significant increase in pasture harvested (P < 0.01) per unit area every year. However with the exception of the first year feed intake per cow was significantly reduced (P<0.01). (g) The ratio of pasture consumed per hectare to milk production per hectare was not significantly affected (P>0.05) by the increase in stocking rate.
-
Item
-
ItemSome effects of botanical composition of pasture on the liveweight and wool production of sheep( 1972)Until recently, the main evidence on which to base pasture mixture. recommendations in Victoria, has been district experience and the results from dry matter ( "mowing") experiments. The grazing experiments described in this thesis, were initiated by Messrs. R. Twentyman, R. Newman, R. Allen and K. Maher of the Department of Agriculture during the period, 1960-196. Their aim was to develop some objective appreciation of the relative value for animal production of some of the sown and unsown species in Western district pastures. In addition to pasture species evaluation, they sought information on the relationship between pasture growth and animal production. Such information is needed so that Agrostologists can better evaluate the many pasture management factors (such as fertilizers, seeding rates, seed. treatments, herbicides, insecticides and defoliation treatments) that affect pasture growth and for which advice is frequently sought.
-
Item
-
ItemStudies on metabolizable energy values of poultry feedstuffs( 1974)This thesis describes studies carried out on metabolizable energy values of a number of feedstuffs available in the State of Victoria for poultry nutrition. These investigations were part of a research project in the poultry research section of S.S.Cameron Laboratory (Animal Research), Werribee. I was responsible for the design and execution of the experiments and for all chemical analyses. The statistical analysis was done by Mr. Jardine, Biometrician, Department of Agriculture, Melbourne. The interpretation of the results and the preparation of the review and the manuscript have been my responsibility. Chapter 1 includes a literature review of the different methods that are used in determining metabolizable energy values for poultry as well as the factors that may affect the metabolizable energy content of diets and feed ingredients. Chapter 2 describes the general procedure of the metabolizable energy assay. The specific material and methods of the experiments were included in each of the experimental chapters. Chapter 3 outlines the balance studies carried out to determine metabolizable energy values of various feedstuffs with different sexes. A comparison between the biologically determined values and those calculated from the chemical composition of the feedstuffs also was included. Chapters 4, 5 and 6 concern the investigations carried out to study the effect of sex of chicks on metabolizable energy content of soyabean, rapeseed, fish meals, tallow and sunflower oil at various levels of inclusion in diets. Chapter 7 summarises the results obtained and recommended avenues for future work. Note: The experimental chapters (3-6) are presented in the format required for publication in the Australian Journal of Experimental Agriculture and Animal Husbandry.
-
ItemThe utilization of livestock wastes by ruminants( 1975)In studies with sheep faeces it was found that the longer the faeces were stored,the lower the content of moisture, crude protein and ether extract and the higher the content of nitrogen free extract. Crude fibre and ash contents were relatively constant. The in vitro technique and the in vivo nylon bag technique to estimate dry matter digestibility (DMD) and organic matter digestibility (OMD) of excreta were investigated. Using an oven as an incubator in the in vitro technique, DMD and OMD coefficients of the faeces of sheep, cattle, pig and the manure of poultry were 19.2, 18.9, 45.7 and 62.6,and 10.9, 8.6, 28.2 and 30.7, respectively. Using a waterbath as an incubator DMD and OMD coefficients were 18.8, 16.8, 31.3 and 53.7,and 17. 0, 14.6, 28.0 and 48.2, respectively. The different techniques are discussed. The in vivo nylon bag technique using nylon "A" in sheep and using nylon "A" and "B" in cattle was carried out for 24, 48, 72 and 96 hours incubation periods. DMD and ODM coefficients are recorded, and the procedures are described. The effects of continuous feeding for 70 days of dried pig faeces, supplemented in the diet of 21 sheep were studied. Seven dietary treatments were imposed. Diet A was a pelleted medium quality hay containing 10.3 mg Cu/kg DM and 0.2 mg Mo/kg DM. Diets B,C and D contained 15% pig faeces which gave a dietary Cu concentration of 101.3 mg/kg; molybdenum was added to diet C to give a concentration of 90 mg/kg DM and to diet D to give a concentration of 175.5 mg/kg DM. Diets E, F and G contained 30% pig faeces (192.5 mg Cu/kg DM) ; molybdenum was added to diet F to give a concentration of 90 mg/kg DM, and to diet G to give a concentration of 175.5 mg/kg DM. Sulphate was added to all diets at the rate of 1.08% of the dry matter. During the experiment all animals survived. Inclusion of dried pig faeces in the diets reduced the digestibility compared with the control diet. The maximum plasma GOT activity detected was 182 units/ml reading at 505 nm wavelength. Blood Cu concentrations ranged from 0.28 ug/ml to 3.50 ug/ml. Wool Cu concentration ranged from 2 to 8 mg/kg DM. Kidney Cu concentration ranged from 19.2 to 190 mg/kg DM. Over the 70 days of the experiment, the Cu retention for groups A - G were, respectively, 210 + 17, 680 + 149, 1191 + 39, 1054 + 20, 53 + 185, 1079 + 164 and 1225 + 157 mg. Liver Cu concentrations were, respectively, 718 + 174, 1186 + 176, 1440 + 248, 1522 + 477, 1740 + 212, 1560 + 46 and 1703 + 384 mg/kg DM. There was no correlation between total Cu intake and Cu retention in the body. However, there was a relationship between total Cu intake and liver Cu concentration ( r = 0.827 ) and between total Cu intake and faecal Cu concentration ( r = 0.997 ). Almost all of Cu output was excreted as a faecal Cu. Histopathological examination showed variable liver damage with some sheep showing single cell necrosis , particularly in the livers of sheep receiving 30% dried pig faeces in the diets. No kidney abnormalities were found. It was concluded that pig faeces, with no processing other than drying, are poorly utilized in the diet of sheep and with continuous feeding may induce copper toxicity.
-
ItemWhole grain for beef cattle( 1979)This thesis consists of a review of feeding processed versus non-processed grain to cattle and reports on several investigations concerned with feeding whole cereal grain to cattle. The experimental section represents a sequence of investigations which attempts to fill information gaps highlighted by the preceding review. They have been prepared as scientific papers and all have been either published or presented for publication. For presentation in this thesis, all have been typed in the one format. I was actively involved in the field work at the Rutherglen Research Station during these investigations, carrying out all of the physical analyses and most of the chemical analyses that were required. I was also responsible for the collation, analysis and interpretation of all the data and the reporting in the scientific papers.
-
Item
-
Item
-
ItemResponses of young sheep to supplements when fed low quality roughages( 1999)The morphological components of which cereal straw is composed vary in composition and nutritive value. In a survey of relevant literature, stem materials (ST) are usually found to be consumed by ruminant animals at a slower rate than leaf material (LF) from the same crop residues when these are fed alone as separated fractions. This is attributed to the higher content of cell wall constituents (CWCs) and often lower content of N of ST. Because ST and LF can vary in proportions in the roughage fed as a basal feed, the response of animals to supplements might also be expected to be variable particularly when the basal feed is offered in excess that permits selection. In particular the response to supplemental N sources varying in ruminai degradability may vary. The objective of this thesis program was to investigate the interactions between the basal roughage and supplement measured as effects on digestion and LW responses of young sheep. The overall hypothesis was that across diets made up of different proportions of LF and ST fractions of cereal straw, the response to N supplements is dependent on CWCs concentration. The program was completed through a series of experiments conducted at the Mt Derrimut Field Satation of the University of Melbourne. In all experiments the animals were fed on a basal feed of LF or ST fractions of barley straw, with supplements including (a) Bar+USS, barley grain (Bar) fortified with urea solution prepared at a ratio of 5:1 (urea plus Na,SO4). (b) USS, urea solution alone added to the basal roughage and (c) FM, fishmeal. With each basal feed one group of lambs did not receive any supplement and served as a control group (CONT). Experiment 1 (Chapter 3) was conducted to evaluate chemical and nutritional characteristics of straw fractions of Parwon cultivar barley. Straw was separated into 4 fractions - stem (ST), leaf blade (LB), leaf sheath (LS) and broken fractions plus weeds (OT). The separated fractions were analysed chemically ( van Soest, 1974) and in vitro digestibility (Tilley and Terry 1964 ) determined. ST was the largest fraction and contained a significantly higher concentration of neutral detergent fibre (NDF; p<0.01) than LB, LS and OT (83.1, 78.6, 76.8,and 71.5 g/100g respectively). ST contained less hemicellulose (HC) than LB but more than LS and OT (37.5, 39.6, 36.3, and 35.7 respectively). N content was lower in ST than in LB, LS and OT fractions (0.4, 0.9, 0.6, and 0.7 respectively). Digestibility in vitro was significantly lower (P<0.001) for ST than for other fractions (38.5, 72.7, 60.1, and 63.0 respectively) while energy required for grinding (Chenost 1966) was much higher (P<0.001) for ST than for other fractions (121, 54.6, 64.2, 56.6 respectivly). In Experiment 2 (Chapter 4) ST and LF fractions of the same Parwon barley straw were fed as the basal feed to lambs and DM intake of ST was 15% lower than for LF (403 vs 473 g/d). When LF feed was supplemented with USS and FM, DM intake was greater by 28% and 25% respectively, while supplementation with Bar+USS resulted in 10% lower LF intake. In contrast, with animals fed ST as the basal roughage, only FM led to an increase in DM intake of only 10%. Supplementation with Bar+US and USS and FM improved overall digestibility, estimated metabolisable energy intake and N intake. Low N intakes on the basal roughages supported low ruminai ammonia-N concentrations (mg/1) immediately before feeding (ST, 20.4 ; LF 35.8), but these were improved where supplements had been fed with each of ST Bar+USS, 263.7; USS, 186.7; and FM, 151) and LF (Bar+USS, 219.5; USS, 62.5; and FM, 150). Six hours after feeding, ammonia-N concentrations (mg/l)were higher for ST (99) still low for LF(35) when fed alone, reduced below the prefeeding levels by supplements of Bar+USS (ST,167; LF 173) but raised by USS (ST, 201; LF 148) and FM (ST, 114; LF, 192). The concentrations of total volatile fatty acids (VFA) in rumen fluid (mMoUl) were not significantly different for ST and LF before feeding except where FM was the supplement, or six hours after feeding except where Bar+USS or USS were fed with LF (before feeding: ST, 51; Bar+USS, 55.7; USS,46.5; FM, 56 ; LF, 42.6; Bar+USS, 53; USS, 55.5; FM, 63.6; 6h after feeding ST, 55.5; Bar+USS, 70.2; USS, 62.1; FM, 50.4 ; LF, 55.7; Bar+USS, 69.5; USS, 60.9; FM, 60.9). Lambs on ST and LF alone lost weight (ST, -105; LF -98 g/d ). Rate of liveweight loss was less when Bar+USS (ST, -32.3; LF -2.4g/d) and USS (ST, -79.8; LF -31.2 g/d) supplements were fed, while FM promoted LW gain (ST, 37.5; LF, 72.4g/d). N retention data was consistent with these LW gains, except where Bar+USS was the supplement, in which case the animals were in positive N balance though losing weight. Wool growth was significantly improved (P<0.001) only by FM on both ST (+47%) and LF (+57%) basal roughages. In Experiments 3 and 4 (Chapter . 5 and 6) the objective was to investigate the factors responsible for low feed intake and poor performance of lambs fed ST compred to those on LF. The DMI (g/d) of lambs fed ST and LF were similar to those achieved in experiment 2; and were significantly greater for LF (P<0.001). Likewise supplements of Bar+USS, USS and FM had similar effects to those reported for experiment 2_ Changes in DMI, MEI ruminai environment before feeding or 6 and:12 hours after feeding were consistent with those recorded during experiment 2. However concentration of total VFA was significantly elevated at 12 hours after feeding. Differences in ruminal environment were evident in terms of VFA concentrations and the distribution of rumen digesta particulate material in different size fractions; both variables were affected both by the basal diet and the supplement. For LF, the proportions of particles >2mm and of very fine particles (0.125 mm) were greater and for particles between 0.5 and 1 mm less those for ST in all cases. Further, the proportion of particles >2mm was less where FM was fed than for any other feeding regime. The mean retention times of rumen fluid, measured from CoEDTA dilution rate, and calculated for rumen particulate material was longer (24%, P<0.01) for ST than for LF but there was no significant effect of supplement on this (Experiment 4, Chapter 6). The mean percentage of very fine particles in the faeces of lambs fed on LF was higher than for lambs fed ST alone or with supplements. Rate of ruminai degradation of OM of ST and LF as measured by nylon bag technique ( Experiment 3, Chapter 5) was similar at 12 and 24 hours but greater for LF than for ST at 48 and 96 hours of incubation. Bar (cracked whole grain) was degraded more rapidly and extensiveley than FM; in LF fed sheep this difference was more marked. Rate of degradation of acid detergent fibre (ADF) was influenced by the kind of supplement and was greatest in lambs given FM , and least in lambs given ST with no supplement. Only the FM supplement resulted in LW gains, though rates of LW loss were least and LW gains with FM were greatest with LF as the basal roughage. The responses are interpreted as flowing from the greater proportion of ADF and lignin in the CWCs content and the greater digestibility of ADF in the LF fraction. The ST feed fraction with higher concentrations of cell wall constituents (CWCs) as NDF was eaten at a slower rate (Experiment 5, Chapter 7) and digesta particulate material and, in these experiments, the fluid phase are retained longer in the rumen. LF showed not only an advantage over ST in these respects but also in terms of a number of important digestion parameters supported a greater response to supplements, particularly N supplements of low degradability. Thus FM is these experiments interacted with the roughage component of the diet. It provided more consistent ruminai ammonia concentrations supporting a better environment for microbial activity and growth. Microbial protein together with undegraded dietary protein together provide a balance of nutrients that allows LW gains on otherwise submaintenance basal feeds. The greater enhancement of performance with LF compared to ST and the particle size measurements suggest that greater fragmentability of LF may be a major contributor . In terms of technical improvement of livestock feeding systems, providing the animal with opportunity for selection of more leaf and less stem may improve the likelihood of responses to supplements but this was not demonstrated in Experiment 5. FM was used as the experimental supplement to provide slowly degraded and undegraded dietary protein of high biological value to the animal. FM is expensive and other crop byproducts and local feed materials with properties of slow degradability of protein and good amino acid balance need to be identified. An alternative strategy would be to provide a maximum opportunity for the selection of most digestible parts. If refusals are then collected, quality could be further improved with alkali treatment and necessary supplementation. This would provide a strategy for the use of morphological fractions which could be an economical approach for the efficient utilization of roughages.