Includes bibliographical references (leaves 197-259). / xv, 261, [9] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. + 1 videocassette (6 min. (VHS) : sd., col. ; 1/2 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1994

Videorecording has title: Effect of antibodies on the motility of rumen ciliates. Bibliography: leaves 197-259. Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates.

Two experiments were conducted. In experiment 1, the objectives were: 1) to develop and evaluate the accuracy and precision of a new continuous ruminal pH measurement system 2) to determine the required frequency for pH electrode standardization and 3) to determine the effect of additional pre-partum concentrate when compared to NRC (2001) recommendations on post-partum ruminal acidosis in primiparous cows. Accuracy and precision of the Lethbridge Research Centre Ruminal pH measurement system (LRCpH) was determined by comparing LRCpH derived values against manual measurement. To determine the required frequency of electrode standardization, three treatments were imposed (24, 48, or 72 h of continuous measurement) and arranged in a repeated 3×3 Latin square design. The LRCpH accurately and precisely measured ruminal pH (repeated measures correlation coefficient = 0.97 and concordance correlation coefficient = 0.97 for 5-min averages). Changes in baseline mV readings for pH readings after 24, 48 or 72 h of ruminal incubation were not significantly different than zero, indicating that daily standardization of new electrodes was not essential. Using the LRCpH to measure ruminal pH overcomes animal mobility restrictions of previous systems. <p>In experiment 2, the effect of additional concentrate allocation during the pre-partum period was evaluated using 14 ruminally cannulated Holstein heifers. The heifers were assigned to one of two feeding regimes pre-calving: 1) control treatment or 2) an intensive high concentrate feeding treatment (HC). All cows received the same lactation diet post-partum. Ruminal pH was measured continuously from d -5 to d +5, and for 3-consecutive days starting on d +17 ± 1.2, d +37 ± 1.4, and d +58 ± 1.5 relative to parturition. Feeding additional concentrate pre-partum did not reduce post-partum ruminal acidosis. In fact, animals fed the HC treatment had more daily episodes of acute acidosis and lower dry matter intake and body condition score than animals fed the control treatment. Day relative to parturition affected the occurrence and severity of ruminal acidosis with a dramatic increase in ruminal acidosis after parturition. This study demonstrates that feeding addition concentrate pre-partum did not reduce post-partum acidosis which emphasized the need to develop and implement feeding strategies that reduce this risk.

Two experiments were conducted. In experiment 1, the objectives were: 1) to develop and evaluate the accuracy and precision of a new continuous ruminal pH measurement system 2) to determine the required frequency for pH electrode standardization and 3) to determine the effect of additional pre-partum concentrate when compared to NRC (2001) recommendations on post-partum ruminal acidosis in primiparous cows. Accuracy and precision of the Lethbridge Research Centre Ruminal pH measurement system (LRCpH) was determined by comparing LRCpH derived values against manual measurement. To determine the required frequency of electrode standardization, three treatments were imposed (24, 48, or 72 h of continuous measurement) and arranged in a repeated 3×3 Latin square design. The LRCpH accurately and precisely measured ruminal pH (repeated measures correlation coefficient = 0.97 and concordance correlation coefficient = 0.97 for 5-min averages). Changes in baseline mV readings for pH readings after 24, 48 or 72 h of ruminal incubation were not significantly different than zero, indicating that daily standardization of new electrodes was not essential. Using the LRCpH to measure ruminal pH overcomes animal mobility restrictions of previous systems. <p>In experiment 2, the effect of additional concentrate allocation during the pre-partum period was evaluated using 14 ruminally cannulated Holstein heifers. The heifers were assigned to one of two feeding regimes pre-calving: 1) control treatment or 2) an intensive high concentrate feeding treatment (HC). All cows received the same lactation diet post-partum. Ruminal pH was measured continuously from d -5 to d +5, and for 3-consecutive days starting on d +17 ± 1.2, d +37 ± 1.4, and d +58 ± 1.5 relative to parturition. Feeding additional concentrate pre-partum did not reduce post-partum ruminal acidosis. In fact, animals fed the HC treatment had more daily episodes of acute acidosis and lower dry matter intake and body condition score than animals fed the control treatment. Day relative to parturition affected the occurrence and severity of ruminal acidosis with a dramatic increase in ruminal acidosis after parturition. This study demonstrates that feeding addition concentrate pre-partum did not reduce post-partum acidosis which emphasized the need to develop and implement feeding strategies that reduce this risk.

Hydrolysis of dietary lipids to free fatty acids (FFA) is a prerequisite for ruminal biohydrogenation, a bacterially mediated process that extensively saturates unsaturated FFAs thus limiting the absorption and ultimate assimilation of these healthy nutrients into ruminant produced foods. Three experiments were conducted to learn how to better enrich, isolate and study lipolytic bacteria from the rumen while providing further characterization of four prominent lipase-producing bacteria that are known to be major contributors of lipolysis in the rumen. In experiment one the effects of various physical treatments on ruminal lipase activity were investigated by comparing incubation positions, glass bead levels, transfer techniques and combinations of headspace gasses. Based on results from this experiment an incubation system was established as a standard for subsequent studies for culturing and transferring mixed and pure cultures of ruminal bacteria. In experiment two the effect of glycerol on lipolysis by Anaerovibrio lipolyticus 5S, Butyrivibrio fibrisolvens 49, Propionibacterium avidum, and Propionibacterium acnes was examined. Two levels of glycerol were examined on lipase activity and results showed that glycerol inhibited rates of FFA accumulation at both levels. In addition the mechanism behind glycerol inhibition was also examined by culturing and assaying activity of the four bacteria to determine if glycerol inhibition is a result of equilibrium displacement or lipase gene expression inhibition. Results indicated that higher and constitutively expressed lipase activity of A. lipolyticus 5S and P. avidum probably contribute more to lipolysis in ruminants than P. acnes and B. fibrisolvens 49. In the case of P. acnes and B. fibrisolvens 49 cells, results suggest that lipase gene expression is down-regulated in these bacteria. Experiment three was conducted to further characterize the lipase activity of the four different bacteria by growing them with four different energy substrates and measuring enzyme activity at early logarithmic and stationary phase. Results from this study showed that diets containing a high content of oleic acid and linolenic acid promoted higher rates of lipolysis in the rumen. In accordance with findings in experiment two these results support that P. avidum may contribute to a higher amount of lipolysis than previously considered.

No description available.

No description available.

The main objective of this work was to investigate the expression of xylanase and cellulose genes from <I>Ruminococcus flavefaciens</I> when introduced into related Gram-positive bacteria including the rumen bacterium <I>Streptococcus bovis</I>. In addition the discovery, and isolation of the β(1,3-1,4)-glucanase gene of <I>S. bovis</I> in the course of this work may provide new possibilities to express foreign genes in <I>S. bovis</I> or in other Gram-positive bacteria. The main findings of this work are summarised below: 1. Genes encoding polysaccharidase activity from the strictly anaerobic rumen bacterium <I>R. flavefaciens</I> can be transferred by electroporation into the ruminal bacterium <I>S. bovis</I> and into other Gram-positive bacteria from different habitats, including <I>Lactococcus lactis, Enterococcus faecalis </I>and <I>Streptococcus sanguis</I>. 2. <I>XynD </I>and <I>endA</I> genes of <I>R. flavefaciens </I>can be expressed from their own promoters in these species. Among the bacteria used as hosts for gene expression, <I>S. bovis </I>gave the highest yields of active enzyme. The expression levels of both gene products were found to be higher in <I>S. bovis</I> than in <I>E. coli</I>. 3. The <I>R. flavefaciens </I>enzymes were mainly secreted in the culture medium of <I>S. bovis</I>; however in <I>E. coli</I> they were mainly cell-associated. 4. The full-length enzyme of <I>xynD</I> was detected in several Gram-positive bacteria, suggesting the effect of proteases may be less than in <I>E. coli</I>. 5. The general rearrangement of the introduced plasmid and genes were not found in Gram-positive bacteria and the genes seem to be stable in these organisms. However rearrangement of <I>xynD</I> was observed in some transformants of <I>S. bovis </I>JB1, although non-rearranged transformants were also obtained. 6. Expression of <I>endA</I> and <I>xynD</I> activity was affected by energy sources supplied to <I>S. bovis</I> cultures, reflecting the accumulation of lactic acid.

Abstract available in PDF file. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1977.

Includes bibliographical references (leaves 197-259). / xv, 261, [9] leaves, [17] leaves of plates : ill. (some col.) ; 30 cm. + 1 videocassette (6 min. (VHS) : sd., col. ; 1/2 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Consists of a review of rumen ciliates, their implications in ruminant nutrition and a description of the research methods, the results and the conclusions drawn with regard to the prospects of establishing an immunological basis for the manipulation of rumen ciliates. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1994