Copper is one of the most important trace elements in ruminant nutrition. Its deficiency causes certain pathologies that can be cured by supplementation, by either five ("inorganic") or complexed ("chelated") forms. With the objective of being able to quantitatively compare the distribution of copper between the two forms of supplements, the speciation of copper in ruminant fluids was studied here. For this study, copper lysine supplement was used. It was necessary to first study the acid-base and complexation chemistry of lysine with copper (II). In addition, the complexation chemistry of glycine and histidine, were investigated. Mass balance equations were used to describe the distribution of copper (II) amongst different ligands. The results of the distribution of copper (II) ions in McDougall's solution (a simulated form of bovine saliva), indicate no significant differences in the distribution of copper using the different form of supplements. 1H NMR was used to validate the results from the computer model. Using a combination of the results from the saliva simulation model and the chemical shifts from the NMR studies, the chemical shift changes that would accompany the addition of copper (II) to McDougall's solution were predicted. Results from the models do not show any appreciable differences from experimental values. Rumen samples were collected. Important peaks in the 1H NMR spectrum were assigned. The spectrum indicated that acetic acid, resulting from the fermentation in the rumen, was a good probe for monitoring the speciation pattern. Speciation calculation indicated that the bulk of the copper would be bound to ammonia in the rumen. Changes in chemical shifts that result from the introduction of copper (II) to the rumen contents were predicted. Results were compared with experimental values. Agreement between the two sets of results was found to be satisfactory. The study shows that any advantages that result from the use of copper lysine supplement are not as a result of its remaining intact. Though metal bioavailabilities are hard to predict this approach could help better our understanding of this process. The methods developed here could be extended to other metal complexation problems in biological fluids. (Abstract shortened by UMI.)

Copper is one of the most vital trace elements in ruminant nutrition. It is required for several metabolic activities and it is also an essential component of several physiologically important metalloenzymes. Thus copper deficiency in ruminants results in distinctive pathologies, and hence in significant economic losses to farmers. Copper deficiency results from very low copper in diet (primary copper deficiency) and interference with Cu absorption in the animal due to Mo and S in food or water (secondary copper deficiency). The molybdenum-induced copper deficiency that affects ruminants can be attributed to the formation of thiomolybdates (TMs)from molybdate and sulfide in the rumen. The TMs formed then react irreversibly with copper to form insoluble Cu-TM complex which ultimately end up being excreted, thus reducing copper bioavailability to the ruminant. <p>In this study, an attempt has been made to use computer simulations to model speciation of copper in rumen fluid in the presence of TMs with the aim of understanding the extent to which TMs affects the levels of copper in the rumen. <p>This was done by initially refining the computer model of copper speciation with respect to low molecular mass (LMM) ligands in bovine rumen with the aim of correcting the discrepancy that was observed during experimental validation of the computer model in a previous study. To this end, mass balance equations which describes the distribution of Cu(II) amongst the different ligands were encoded into a spreadsheet to calculate equilibrium concentration of all species. Formation constants obtained from literature as well as those obtained from studies in our group were used as input values in the spreadsheet. Results show that at average ruminal pH, the metal would be present mostly as carbonate and phosphate complexes. The results obtained from the computer model in the present study were validated using 1H NMR experiments on simulated rumen fluid as well as actual rumen fluid containing Cu(II); using acetic acid chemical shift as the probe for monitoring the speciation pattern. Excellent agreement was observed between the computer model and experimental results. Discrepancy was however observed upon introduction of copper lysine as copper source into the model. Incorporation of a mixed ligand complex of Cu(II), acetate and lysine into the computer model gave an excellent agreement between the computer model and experimental results. <p>The study was extended to include glycine, histidine, methionine and EDTA complexes as the copper source in both rumen saliva (McDougalls solution) and rumen fluid. Results show that only the histidine and EDTA complexes persist to any significant extent, in spite of the large number of competing ligands present in these matrices.<p>In this study, success has also been achieved in the integration of the slow (kinetically controlled) formation of TMs and copper-tetrathiomolybdate (TM4) complexation into the previously developed model for the rapidly equilibrating copper-ligand speciation. To simulate the formation of the TMs and Cu-TM4 complex with respect to time, the differential equations representing rate expressions for each chemical species were solved to obtain an analytical solution using the Laplace transform method. The analytical solutions obtained were encoded in a spreadsheet and calculated as function of time to obtain time dependent concentrations of TMs and Cu-TM4 complex. This was then integrated with previously developed model for the rapidly equilibrating copper-ligand speciation in the rumen. The kinetic data used in the simulation of the formation thiomolybdates was obtained fron literature wheras that for Cu-TM4 complexation was obtained from our lab using Cu(II) - Ion Selective Electrode. The results show that that in the presence of TM4 the, Cu(II) bound to low molecular ligands in the rumen is drastically reduced confirming the effect TM4 on Cu(II) observed in several in vitro studies.<p>The study shows that in thiomolybdate contaminated rumen environment, the bioavailability of copper is considerably reduced. Though metal bioavailabilities are hard to predict this approach could help better our understanding of this process.

The objective of this study was to determine the effects of method of barley grain processing (dry-rolled vs. pelleted barley) and source of oilseed (ground canola vs. ground flaxseed), arranged as a 2 x 2 factorial, on feed intake, ruminal fermentation, nutrient flow to the duodenum, and milk production and composition in dairy cows. Eight Holstein cows (655 ± 69 kg; 83 ± 16 DIM) were used in a replicated 4 x 4 Latin square with 28-d periods. Cows in one square were fitted with ruminal and duodenal cannulae. Cows fed dry-rolled barley consumed 1.8 to 3.5 kg/d more (P = 0.02) DM than those fed pelleted barley; however, source of supplemental dietary fat had no effect on DM intake. Ruminal pH was lower (P = 0.045) in cows fed pelleted barley compared to those fed dry-rolled barley. Ruminal concentration of acetate was greater (P = 0.001), whereas ruminal concentration of propionate tended to be lower (P = 0.11), in cows fed dry-rolled barley compared to those fed pelleted barley; consequently, the acetate:propionate ratio was higher (P = 0.01) in cows fed dry-rolled barley compared to those fed pelleted barley. Ruminal concentration of total VFA was unaffected (P > 0.05) by diet. Source of dietary fat had no effect on ruminal digestion of OM, NDF, ADF or starch; however, ruminal starch digestion was slightly higher in cows fed pelleted barley compared to those fed dry-rolled barley (90.8 vs. 89.5%). Total dietary fatty acid intake was higher (P < 0.05) in cows consuming dry-rolled barley compared to those fed pelleted barley. Duodenal flow of C18:0 was lower, whereas that of C18:2n6c was higher (P < 0.05) in cows fed pelleted barley compared to those fed dry-rolled barley. Feeding flaxseed increased duodenal flows of C18:3n3, cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid compared to feeding canola. Milk yield was unaffected (P > 0.05) by diet; however, milk fat content was higher (P = 0.004) in cows fed dry-rolled barley compared to those fed pelleted barley. Milk fat content of C18:3 was higher (P = 0.005) in cows fed canola compared to those fed flax. Milk fat content of C18:3 and cis-9, trans-11 C18:2 were higher in cows fed pelleted barley compared to those fed dry-rolled barley with flax as the source of oilseed, but not with canola (interaction, P < 0.01). Milk fat content of saturated fatty acids decreased (P < 0.001) and that of polyunsaturated fatty acids increased (P = 0.003) in cows fed pelleted barley compared to those fed dry-rolled barley. In summary, milk fatty acid profiles were altered by method of grain processing and source of oilseed.

Copper (Cu) is an essential trace element in ruminants such as the cow. Its deficiency leads to a number of debilitating symptoms and can eventually cause death. Secondary Cu deficiency is caused by the presence of chemical antagonists such as the thiomolybdates (TMs) (MoOxS4-x2-; x = 0 3). TMs form in the rumen and then form tightly bound insoluble complexes with Cu. These complexes are then excreted and the Cu is unavailable to the animal. The TMs and their effects on ruminant Cu are the focus of this thesis.<p>This study includes three main bodies of work. First, a method for quantifying the composition of TM mixtures in solution was developed. Second, the rate constants of TM interconversions were determined. Third, reactions between Cu and the TMs were studied. This work is part of an ongoing study in the Reid group to model Cu-ligand speciation in the rumen. <p>Thiomolybdates form by successive replacement of molybdate (MoO42-) O ligands with S. This makes synthesis of the uncontaminated compounds difficult. Mixtures of TMs are best analyzed by UV-visible spectroscopy despite the considerable spectral overlap. The combination of these two issues makes the characterization of the spectra difficult. In this study, a method was developed to establish the spectra of the pure TMs despite cross-contamination. Multivariate curve fitting methods were used to establish the composition of synthesized samples simultaneously with the molar absorptivities of the pure TMs. This was done using a Beers Law model. The composition was determined from a fit using assumed molar absorptivities. The absorptivities were then refined using the composition results. These processes were successively reiterated until both were optimized. The optimized absorptivities could then be used to determine the composition of any TM solution mixture. <p>The kinetics of TM formation under biologically relevant conditions were followed by UV-visible spectroscopy. The spectra were then analyzed, using the method developed above, to determine all TM concentrations. Curve fitting methods were used to simultaneously determine the rate constants of all processes that occurred. Integrated rate equations used in the fitting process were developed using the Laplace Transform method. Rate constants were determined at varying pH, ionic strengths and temperatures. From this information it was shown that TM formation and hydrolysis occurs via an associative mechanism. It was also determined that H2S and not HS- was the sulfide nucleophile in TM formation reactions.<p>This study was then extended to include reactions involving Cu and the TMs. First, the UV-visible spectra of the reaction products of Cu with each TM were characterized. This allowed the kinetics of reactions between Cu and the TMs to be followed. This reaction has been found to proceed via an intermediate. Molar absorptivities for this intermediate were optimized along with the appropriate rate constants. This was done using a combination of mathematical simulations and the curve fitting methods used for the TM kinetics. The resulting rate constants can be compared with those obtained previously in the group using a Cu ion selective electrode. <p>These rate constants were used in conjunction with the TM formation rate constants to perform simulations. The results of these simulations provide a picture of what is expected to occur in the rumen. Reactions were also performed in which TM formation occurred in the presence of Cu. This was then extended to mimic bovine feeding habits. Here, portions of the reactions mixture was removed at various time intervals and replaced with fresh reagents. These experiments were used to gain a qualitative picture of Cu speciation in the presence of the TMs over time. The work presented in this thesis provides a crucial step toward understanding the problem of bovine copper deficiency.

Ces travaux étudient l'impact de la solubilité dans l'eau du phosphore (P) chez l'animal. L'alimentation phosphorée des animaux à été extrême puisque 70% de P de la ration a été apportée par des sources inorganiques (monocalcique= soluble et bicalcique= insoluble). Ces situations ne sont pas représentatives des conditions d'élevage où, le P inorganique représente une moindre proportion de P total de la ration. La chèvre laitière a été utilisée comme modèle animal. L'objectif de la première étude a été de déterminer, l'impact de la solubilité de P sur l'activité fermentaire et les variations de la teneur en P des bactéries associées aux phases liquide et solide. Ce travail rapporte pour première fois le taux de sortie de P du rumen de même que les variations de la teneur en P des bactéries. La deuxième étude a eu comme objectif de déterminer l'effet de la solubilité de P sur son utilisation digestive et métabolique et de préciser le cycle de mobilisation et restauration osseuse au cours d'un cycle complet de lactation. L'effet de la solubilité de P a été observé sur l'activité bactérienne (représenté par les cinétiques des acides gras volatils). Les bactéries associes à la phase liquide ont été les plus affectées par la différence de solubilité. Les bactéries semblent s'adapter aux variations des concentrations en P. L'utilisation digestive et métabolique des phosphates n'a pas montré de différences associées à la solubilité, mais au stade de lactation. Des différences des concentrations du marqueur de résorption osseuse (cross links de collagène type I) ont été observées. Ces différences pourraient être attribuées à une utilisation métabolique différente. Des recherches complémentaires sont nécessaires pour préciser la cinétique de P dans le rumen et du métabolisme des bactéries ruminales. La chèvre laitière présente des différences adaptatives pour augmenter l'absorption apparente de P au début de lactation, tandis que chez la brebis, l'adaptation est observée vers mi lactation.

No description available.

Four lactating Holstein cows fitted with ruminal and duodenal cannulae were used in a 4 x 4 Latin square design to determine the effects of feeding raw and heat-treated flaxseed on ruminal fermentation parameters, ruminal fatty acid biohydrogenation (BH), nutrient utilization in various segments of the gastrointestinal tract, and plasma and milk composition of lactating dairy cows. Four diets were formulated: a control diet with no flaxseed (C); a raw flaxseed (RF); a micronized flaxseed (MF); and an extruded flaxseed (EF) diet. Ruminal pH, NH3N and total volatile fatty acids were not affected by dietary treatments. However, feeding flaxseed decreased ( P < 0.01) molar proportion of acetate and increased ( P < 0.01) that of propionate. Ruminal fiber digestion was lower (P < 0.04) for cows fed the flaxseed diets relative to those fed C. Feeding flaxseed had no effect on milk yield, milk fat and protein content, and milk fat yield, but decreased (P = 0.02) milk protein yield. (Abstract shortened by UMI.)

Bandymas atliktas siekiant ištirti didžiojo prieskrandžio biocheminius ir mikrobiologinius rodiklius, šeriant karves skirtingos sudėties racionais; įvertinti didžiojo prieskrandžio fermentacinį aktyvumą; ištirti žolinių pašarų – šieno, šienainio, kukurūzų siloso virškinamumą in vitro, inkubuojant juos su skirtingo fermentacinio aktyvumo didžiojo prieskrandžio turiniu. Iš gautų rezultatų galime teigti, kad skirtingos sudėties racionai turi įtakos karvių didžiojo prieskrandžio turinio mikrobiologiniams ir biocheminiams rodikliams. Nustatyta, kad I (kontrolinės) grupės karvių didžiojo prieskrandžio turinio ph buvo 10,5 proc. (p<0,0001) mažesnis; redukcinis bakterijų aktyvumas vyko 131 s (p<0,0001) greičiau; gliukozės rūgimo reakcija buvo 71,4 proc. (p<0,0001) didesnė; pirmuonių rasta 120 103/ (p<0,0001) daugiau; LRR gamyba padidėjo 27,2 proc. palyginant su II (bandomosios) grupės karvėmis, kurios buvo šeriamos nesubalansuotu racionu. Subalansuoto raciono įvairesni ir maistingesni pašarai nulėmė, kontrolinės grupės aktyvesnį didžiojo prieskrandžio turinio fermentacinį procesą. Subalansuotame racione vyravo šienainis (55 proc.), kukurūzų silosas (20 proc.) ir kombinuotieji pašarai (20,7 proc.). Racionas buvo praturtintas melasa (0,62 proc.) ir BVMP (0,37 proc.). Bandomosios karvės iš sultingųjų pašarų gavo tik kukurūzų siloso, kuris ir sudarė didžiausią raciono dalį (75 proc.). Jų racione nebuvo šienainio, kuris yra 2-3 kartus maistingesnis palyginti su kukurūzų silosu (2... [toliau žr. visą tekstą] / Aim of thesis: to analyse the dependence of forage organic material digestion on the level of cows’ long prestomach fermentation. Tasks: 1. To estimate biochemical and microbiological factors of large prestomach content of cows, fed by different consist rations and to evaluate fermentational activity; 2. To examine herby forage- hay, haylage and maize silage- organic material digestion in vitro by incubating them with different fermentational activity content of long prestomach. In the course of work the following was identified: 1. Ph of long prestomach content of cows fed by balanced ration was 10,5 % (p<0,0001) lower, the reaction of bacteria reductional activity was 131 s (p<0,0001) faster, the reaction of glucoses fermentation was 71,4 % (p<0,0001) higher, protoza was found 120 103 / ml (p<0,0001) more, the production of free fatty acids increased by 27,2 % (p<0,0001) in comparison with cows, which were fed by unbalanced ration. 1.1. Therefore fermentational processes of long prestomach of cows fed by balanced ration were active, and of those fed by unbalanced ration- slowed down. 2. When incubating hay, haylage and silage in vitro with different fermentational activity content of long prestomach, organic material digestion (OMD) of all examined forage was highest by incubating them with active fermentation long prestomach content: 2.1. organic material digestion (OMD) was of hay 5,52 % (p<0,0001) higher; organic material digestion (OMD) was of haylage 5,5 % (p<0,0001)... [to full text]

The objective of this study was to determine the ability of a passive temperature monitoring system consisting of radio frequency identification (RFID) boluses with thermistors and receiver panels to detect ovulation in high performing dairy cows. The twice-daily reticulo-rumen temperature (Trr) acquisitions of 41 early-lactation Holstein dairy cows were analyzed. The data were analyzed using two criteria: six baseline days (2d, 3d, 4d, 5d, 6d, 7d) and four temperature deviations (0.2°C, 0.3°C, 0.4°C, 0.5°C). The best criteria were chosen by selecting the baseline/deviation combination that gave the best positive predictive value (PPV). The system detected 93 true positive and 267 false positive alerts of ovulation, with a monitoring rate (MR) of 47% and a PPV of 46.2%. There were indications that the Cow Temperature Monitoring System could have a future as an ovulation detection aid, but due to the unreliability of the Wi-Fi transmission of acquisitions, more research needs to be conducted before definite conclusions can be drawn.

The yeast expression system Pichia pastoris was investigated as an encapsulation technology capable of serving as a rumen escape vehicle. Cellularly encapsulated protein is protected from the ruminal environment so long as the cell membrane, which surrounds and isolates the intracellular protein is physically intact. Intracellular expression of Green Fluorescent Protein (GFP) allows for the monitoring of cellular integrity as necessary for the protection of encapsulated protein from ruminal proteases. Upon cellular lysis GFP is exposed to extracellular proteases which result in both the proteolytic degradation of the protein-based GFP chromophore and its associated fluorescence. Visualization of rumen fluid under epifluorescent microscopy revealed a high level of background autofluorescence owing to the fluorescent plant particles, microbes, and fluorescent compounds therein. Visualization of GFP in rumen fluid can be optimized through GFP variant selection, filter set design, and light source selection based on bulb emission spectra. Incubation of intracellular GFP expressing P. pastoris in batch culture ruminal in vitro simulations demonstrated that 93%, 97%, and 25% of the P. pastoris inoculum maintained cellular integrity in clarified rumen fluid, bacterial fraction of rumen fluid, and whole rumen fluid, respectively, when incubated over 36 to 48 h. Continuous fermentation in vitro rumen simulations (Rusitec) demonstrated a P. pastoris escape rate of 19% when added daily to fully adapted Rusitec vessels having a dilution rate of 0.75d-1. Abomasal in vitro simulations demonstrated that 84% of the P. pastoris inoculum was lysed within 12 h, as necessary for the release of encapsulated protein. P.pastoris may be an effective post-fuminal delivery vehicle, provided that similar results are obtained in vivo. / xiv, 120 leaves : ill. ; 28 cm.