Agriculture and Food Systems - Theses
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ItemNutritional modification of muscle long-chain omega-3 fatty acids in lambs : effects on growth, and composition and quality of meat( 1999)Three experiments were conducted to investigate the effects of dietary supplements rich in omega-3 fatty acid on muscle omega-3 fatty acid deposition. The consequential effects on growth performance of lambs, colour and lipid oxidative stability of muscle over refrigerated display, and the sensory properties of cooked meat were also examined. A mixture of lucerne chaff : oaten chaff was used as basal diet, offered in different proportions were fed to lambs ad libitum (Expt. 1) or at 90% ad libitum (Expts. 2 and 3). Such mixtures of roughage diet support slow growth and provide a feed quality pattern similar to late spring to late summer pasture. In Expt. 1, fish meal (7%), canola meal (8%) and soymeal (7%) as natural feed supplements were compared in lambs fed low quality roughage diet. In Expt. 2, fish meal (9%) and oilseed supplements either in unprotected form (rapeseed - 7%) or in protected form (ground canola seed - 6%) were examined in lambs on medium quality roughage diet. Lipids and the proteins in the ground canola seed were treated (RUMENTEK) with aldehyde to protect them from the rumen microbial activity. Fish meal (9%), fish oil (1.5%), fish oil (1.5%) with sunflower meal protein (9%),' and sunflower meal protein alone (10.5%) (a commercial product of a protein supplement from RUMENTEK) were compared in lambs fed medium quality roughage diet in Expt. 3. Long-chain omega-3 fatty acids (eicosapentaenoic acid + docosahexaenoic acid) in muscle longissimus thoracis was increased modestly and markedly with fish meal and fish oil alone or with sunflower meal protein diet, respectively. These long-chain fatty acids were deposited in the muscle structural phospholipid rather than in storage triglycerides. All the diets mentioned above also significantly reduced omega-6:omega-3 fatty acid ratio in meat which is another beneficial effect, as the dietary recommendation in many countries has been to reduce the ratio of omega-6:omega-3 in human diet. Soymeal diet increased modestly both the omega-3 and omega-6 fatty acid content of muscle longissimus thoracis resulting in no differences in the omega-6:omega-3 ratio of the meat. A supplement of protected canola seed significantly increased the precursors of omega-6 (linoleic) and omega-3 (linolenic) but not the long-chain analogues such as arachidonic acid (omega-6) and eicosapentaenoic, docosahexaenoic acid (omega-3), respectively. The marked increase in linoleic acid content was in both triglyceride and phospholipid fractions of muscle longissimus thoracis but the modest increase in linolenic acid content was only in triglyceride fraction of meat. Supplements of canola meal used in Expt. 1, unprotected rapeseed used in Expt. 2 and protected sunflower meal protein used in Expt. 3 did not alter the fatty acid composition of muscle longissimus thoracis compared with lambs fed the control diet in that particular experiment. The increased level of long-chain omega-3 fatty acid and/or omega-6 fatty acid with the lipid supplements discussed above did not significantly affect the meat colour stability and lipid oxidative stability of fresh and vacuum packaged meat over the storage at refrigerated display. This suggests that the conditions under which the animals are grown (grazing vs grain fed or feedlot) and the species of animal are important in determining the oxidative stabilities of meat by altering the levels of muscle vitamin E concentrations at slaughter. The level of inclusion of lucerne chaff in the basal diet is an important factor in improving the redness of meat indicated by the a*-value; a higher level of lucerne chaff intake is more likely to be associated with increased intake of vitamin E. Thus colour and lipid oxidative stabilities of meat can be improved in red meat animals that are on poor quality diets by the inclusion of lucerne chaff in their diet. The sensory properties of cooked meat evaluated in the present study were not affected by the significant increase in muscle long-chain omega-3 fatty acid or omega-6 fatty acid content with fish oil and protected canola seed supplements, respectively. Addition of protected sunflower meal as a protein supplement together with fish oil significantly lowered the ratings of flavour and overall acceptability of meat compared with the control lambs. The results demonstrate that the common `lamby' and `muttony' flavour and aroma attributes were not hidden by any of the dietary treatments. These two characters associated with the species flavour and aroma were recognised by the panellists as a distinct attribute. Dry matter intake was not adversely affected by any of the lipid supplements used in the present study. Feed conversion efficiency was highest with fish meal diet on both low and medium quality roughage diets. At medium quality roughage-based diet, Feed conversion efficiency was modestly improved by protected canola seed diet but other supplements providing either natural (unprotected rapeseed) or protected protein (protected sunflower meal) did not support significant differences compared with basal diet. The significant increase in liveweight gain with fish meal diet reflected a significant increase in hot carcass weight compared with all other supplemented lambs either on low or on medium quality roughage diet. Protected lipid and protein offered by protected canola seed diet significantly and moderately increased liveweight gain and hot carcass weight from control diet but not different from unprotected rapeseed diet. The greatest muscle deposition was with the fish meal diet and is attributed mainly to the increased amount of protein and energy absorbed from the small intestine of those lambs. In addition to energy and protein absorption, the alteration of omega-3 polyunsaturated fatty acids in muscle membranes may have a further influence in lean meat production. In terms of carcass gain and intramuscular fat deposition of fishmeal and fish oil fed lambs, the results also lead to a hypothesis that modifying omega-3 polyunsaturated fatty acid of muscle membrane phospholipids may have an influence in improved muscle deposition in lambs by improving the insulin action at skeletal muscle site.
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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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ItemEffects of dietary inclusion of chickpeas or mung beans on the performance of male broiler chicks( 1991)Male broiler chicks (Inghams) were reared to 5 days of age on a commercial starter ration and then fed a control diet or a diet containing 10, 20, 30, 40 or 50% of either chickpeas or mung beans up to 28 days of age. At the end of the feeding trial, a sample of birds from each group were sacrificed for carcass and visceral organ assessment. The chickpeas, mung beans and other ingredient grains were assayed for trypsin inhibitor (TI), chymotrypsin inhibitor (CTI), tannin and haemagglutinin activities. The diets were assayed for apparent metabolizable energy (AME), TI and CTI. Average daily feed intake (FI) ranged from 66.89 � 1.96 to 76.23 1.96g showing a significant (P< 0.01) reduction in FI with increasing level of either bean. Average daily live weight gain (ADG) varied from 37.38 � 1.07 to 45.43 � 1.61g showing a linear and highly significant (P< 0.001) decrease in ADG as the level of both chickpeas and mung beans increased. Feed conversion efficiency deteriorated with increasing level of beans in the diets (P< 0.001) and chickpeas showed poorer FCR than mung beans (P< 0.01). AME of the diets ranged from 11.4 to 12.6 MJ/Kg indicating a significant (P< 0.05) reduction in energy efficiency as the level of either bean increased. Fasted live weight of chicks on 28th day of age ranged from 928 90 to 1114 � l Og (P< 0.001). Birds grown on mung bean diets had nonsignificantly (P> 0.05) higher live weight and carcass output than those on chickpeas while those grown on the, control diet yielded significantly higher (P< 0.01) carcass output. Actual weights of both pancreas and intestines and their weights as percentage of live weight significantly increased (P< 0.001) with increasing levels of either bean and the increase was comparatively greater for chickpeas than for mung beans. There was no significant variation in actual weight of liver but the weight of liver as percentage of live weight significantly increased (P< 0.05) as the level of either bean increased. TI, CTI, tannin and haemagglutinating activities in chickpeas and mung beans were 3.25 vs 3.35, 4.30 vs 0.24, 6.4 vs 9.4mg/g and 6.4 vs 51.2HU/g respectively while TI and CTI activities in the control diet wwle 0.04 and 0.00 respectively. Levels of ANFs increased as level of either bean in the diet increased, hence performance of chicks declined linearly. Among the ANFs detected, the level of total protease inhibitors (TI + Cf I ) activity gives clear explanation for the variation in chick performance. In addition, it was suggested that the poorer performance of chicks on chickpea diets could also be attributed to lower digestibility and availability of carbohydrates in chickpeas. 2
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ItemGrowth and digestibility in finishing pigs fed various levels of raw mung beans (Phaseolus aureus [Roxb.] var. Berkin)( 1991)Two experiments were conducted to evaluate raw mung beans (Phaseolus aureus [Roxb] var. Berkin) as a source of protein and energy for finishing pigs. In the first experiment, 6 cross-bred (Landrace X Large White) boars of 53 kg liveweight were used to determine the digestible energy (DE) content of ground mung beans by substitution where 30% ground mung beans were included in a basal (wheat) diet at the expense of wheat. The DE content of mung beans was 16 � 0.9 MJ/kg DM. In the second experiment, 24 boars of 58 - 65 kg liveweight were allocated to 6 groups of four and individually fed diets containing 0% (control), 10%, 15%, 20%, 25% and 30% mung beans substituting for the same amount of soybean meal. All diets contained 14.5 MJ DE/kg and an estimated 0.65 g lysine/MJ DE.. Daily feed allowance was restricted to approximately 35 MJ DE. There was no significant difference (P>0.05) between treatments in average daily gain (ADG), feed conversion ratio (FCR), backfat (P2) or relative weights of pancreas, liver, kidney, stomach, small intestine and large intestine. The ADG and FCR were 0.96 � 0.02 kg and 2.60 � 0.05 units of feed/units of gain respectively, whilst P2 was 15.9 � 0.27 mm. The weight of the pancreas, liver, kidney, stomach, small intestine and large intestine relative to body weight were 0.15 � 0.01; 2.07 � 0.03; 0.39 � 0.01; 0.61 � 0.01; 1.96 � 0.03 and 1.41 � 0.03 per cent respectively. Organic matter (OM) and ether extract (EE) digestibilities were not affected by the levels of mung beans, but levels beyond 20% significantly (P< 0.05) decreased apparent digestibility of crude protein (CP) and increased digestibility of neutral detergent fibre (NDF). Under the condition of this study, this variety of mung beans can be incorporated in finisher diets up to 30% without negative effects on growth performance.
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ItemPasture utilization for wool growth of weaner sheep in south western Victoria( 1988)Two series of experiments are described in this thesis. The first set of experiments report on the use of young, oesophageally fistulated sheep to collect herbage samples in grazing experiments. Secondly, the biological responses of Merino and Comeback weaner sheep to changes in pasture type and season of birth are described. The experiments were conducted at the Pastoral Research Institute, Hamilton, Victoria during 1982-86, where the author is employed as a Science Officer by the Victorian Department of Agriculture and Rural Affairs. Chapters 4 and 5 report the effects of several variables on the chemical composition of oesophageal fistula samples and have been submitted for publication (see below). Mr. P.C. Flinn and Professor A.R. Egan have been included as co-authors of Chapter 4 due to their contribution to chemical analysis of samples, and to planning of the experiment respectively. Mr. P.C. Flinn and Mr. J.F. Heard have been included as co-authors due to their assistance during the experiment described in Chapter 5. Differences between the growth, composition and nutritive value of lucerne/subterranean clover and perennial ryegrass/subterranean clover pastures are reported in Chapter 6. (More detailed data on the growth and composition of the pastures is available on request to the author). The effects of these pastures on the productivity of autumn and spring born, Merino and Comeback weaner sheep are presented in Chapters 7 and 8. It. is intended to submit these three chapters for publication. Mr. R.L. Thompson and Dr. J.M. Obst will be. included as co-authors when the results reported in Chapter 7 are published. The experiments reported in this thesis make up part of a larger project (Sheep Production Systems) for which Mr. Thompson and Dr. Obst are responsible. However I accept full responsibility for the collection of all data, analysis of results and preparation of the manuscripts. In addition, I was responsible for the design of experiments reported in Chapters 4, 5, 6 and 8. Details of publications are as follows:- Chapter 4 : Saul, G.R., Flinn, P.C. and Egan, A.R. (1988). The effect of fasting, breed and sample size on the chemical composition of pasture samples from fistulated weaned lambs (submitted to Australian Journal of Experimental Agriculture). Chapter 5 : Saul, G.R., Flinn, P.C. and Heard, J.F. (1986). The nutritive value of roughages before and after mastication by oesophageally fistulated sheep. Proceedings Australian Society of Animal Production 16, 351-54.
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ItemSome factors affecting efficiency of meat production from cattle( 1972)The main aim of the present work was to examine efficiency of production in beef cows. Efficiency of production is defined as the weight of calf produced divided by the feed consumed to produce that calf or those calves. This type of study takes a long time and, among other things, measurement of feed consumption is required. Neither in Australia nor overseas is there sufficient information of this type available for such study of beef cows. An alternative approach may be through "estimation" of cow feed intake from her weight by formulas in which the total requirement of feed is calculated from the maintenance requirements plus the requirement for production. It is generally accepted that both maintenance requirement and requirement of feed for production are proportional to a certain power of body weight. However, this procedure is of doubtful utility since several factors have been shown to affect maintenance requirement: lactation status (Neville and McCullough 1969), age (Brody 1945), level of nutrition (Lofgreen and Garret 1968), environmental conditions (Lambourn and Reardon 1963), parasites (Vercoe and O'Kelly 1972). There is also disagreement as to which power bodyweight must be raised in order to yield an appropriate value (Brody 1945; Kleiber 1961; Graham 1972). Furthermore, factors like appetite and individual variation are not considered in this type of approach. Because of the uncertainty of determining feed requirement from bodyweight data and of the difficulties in finding data directly pertaining to the question contained in the aim, I have studied various aspects of the major problem in the available beef cattle data. They are presented in Chapter II. To deal with the principal problem, I conducted an experiment with mice analagous to one required to study the problem directly with cattle. In this experiment feed intake was controlled. It was possible to examine in detail at some of the variables determining efficiency of production. The mice experiment is considered in Chapter III. In addition, I reviewed the literature in which factors like growth, longevity and fertility are considered as affecting efficiency of production. (Chapter I).
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ItemThe influence of nutritional factors in the development of postweaning diarrhoea in early weaned pigs( 1984)1. The study concerned the significance of change of diet and feeding method on the clinical, pathological and growth responses of 3- to 4-week-old pigs when subjected either to challenge with an enterotoxigenic serotype of Escherichia coli or exposed to 'natural' infection with E.coli. It involved experiments with both hysterotomy-derived specific pathogen-free (SPF) piglets and conventionally reared animals. The dietary treatments involved comparisons between (i) wet versus dry feeding and (ii) skim milk versus soyabean (SB) meal as the major dietary protein source. 2. Under closely controlled SPF conditions, thirty-five 28-day-old piglets were used in five experiments. In the first four experiments, two groups were changed from a liquid cow's milk diet to a milk-based diet (termed the 'basal' diet), given either in wet or dry form. Within each group, half of the animals were orally challenged with enterotoxigenic E.coli (ETEC) bearing the K88 antigen and the remainder, serving as controls, were challenged with a non-pathogenic K12 E.coli strain. ETEC-infected piglets fed the dry, basal diet developed severe diarrhoea, depression and dehydration and at necropsy exhibited severe lesions in the small intestine associated with extensive bacterial adherence and marked reduction in intestinal lactase activity. Infected piglets fed the basal diet as a gruel had only mild diarrhoea, accompanied by limited bacterial adherence and minor mucosal and physiological changes. Control piglets, fed either dry or wet, remained clinically healthy and the morphology of the intestinal mucosa was normal. In the fifth experiment, two groups were changed from the liquid cow's milk diet to either a dry-fed basal diet or a dry-fed SB-based diet; each group consisted of both infected and control animals. Control piglets on both diets remained clinically normal with only minor mucosal changes; but the intestinal lactase activity of those fed the SB diet was depressed. Infected piglets fed the SB diet developed mild diarrhoea, depression and dehydration. Infected piglets fed the basal diet had no diarrhoea but were depressed. Bacterial colonization, mucosal and physiological changes were relatively more severe in the SB-fed animals than in those fed the basal diet. 3. Under conventional conditions, a total 0f one hundred and seventy-six piglets, from the Mt Derrimut herd, were used in three experiments. In each of these experiments, pigs were allocated among four dietary treatments: dry, basal; wet, basal; dry, SB; and wet, SB. In Expt 1, a total of twenty-four pigs were orally inoculated with K88 ETEC following their transfer at weaning to non-specialized pen accommodation (at the Attwood Institute for Veterinary Research). In Expts 2 and 3, (conducted at the Mt Derrimut Pig Centre), ninety-six and fifty-six pigs respectively were moved at weaning into specialized weaner accommodation that was routinely used for early weaning on a batch basis. No inoculations with ETEC were performed in these two experiments. In Expt 1, all pigs remained clinically normal except for one pig fed the SB diet dry. Post-mortem studies conducted on four selected pigs from each treatment group revealed very limited colonization by ETEC but without marked changes in gut morphology (although K88 ETEC were present in faecal materials). In Expts 2 and 3, natural infection with ETEC and manifestation of PWD (postweaning diarrhoea) occurred. As compared with the SB diet, the basal diet particularly when fed wet, resulted in a less severe diarrhoea. Morphological and physiological changes in the small intestine were less pronounced and bacterial adherence was less extensive. Whether the SB diet was fed wet or dry made little difference in these respects. In the first 14 days post-weaning pigs fed the basal diet, especially when this was fed wet, made faster and more efficient weight gains than those given the SB diet. The degree of infection was more widespread and severe in Expt 3 than in Expt 2. In Expt 3, the superiority of the milk-based diet compared to the SB diet was relatively greater during the first 14 days post-weaning. 4. The results indicated that both the type of diet and the form in which the diet was fed, significantly influenced the extent of colonization of the gut by ETEC, the severity of PWD and growth performance. The effects of feeding method were more apparent in the SPF piglets than in the conventional piglets. This was attributed to the greater influence of uncontrolled variables in the latter situation. 5. The greater variability of performance under the conventional rearing conditions and the marked difference in response to ETEC in Expt 1 compared with that in Expts 2 and 3 suggest that in addition to the dietary factors examined, other factors, such as the immune status of the animal, the level of 'background' pathogenic challenge and the physical environment were implicated in the pathogenesis of PWD.