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PubMed1985

Effects of zinc deficiency on the wool growth, skin and wool follicles of pre-ruminant lambs.

Two groups of 1-month-old pre-ruminant lambs of similar mean liveweights were fed identical liquid milk-replacer diets except that the zinc contents were either 5 micrograms (deficient diet) or 32 micrograms per gram of dry matter (control diet). These diets were fed for 4 weeks, after which all the lambs received the control diet for 2 weeks. In the lambs fed the deficient diet plasma zinc concentration decreased markedly during the first 2 weeks and skin lesions developed around their mouths. Autophagic vacuoles also developed in most follicle bulbs along with a variety of defects in the wool fibres and progressive inhibition of wool growth. Food intake and liveweight increase were not significantly depressed until the third and fourth weeks of feeding the deficient diet. During this period the wool was shed from the zinc-deficient lambs as a result of the fibres being degraded and distorted within thickened outer root sheaths in the distal (upper) parts of the follicles. In addition, the epidermis of the wool-bearing skin became slightly acanthotic and hyperkeratotic, although not parakeratotic. When the deficient lambs were fed the control diet for 2 weeks, their food intake, liveweight gain and plasma zinc concentration increased to almost those of the control lambs, but their rate of wool growth was still low and the epidermis had not returned to normal. Compared with previous studies the findings of this study suggest that pre-ruminant lambs may be more susceptible to the effects of zinc deficiency than ruminant lambs.

Aging↗

PubMed1982

The origin of urinary aromatic compounds excreted by ruminants. 1. The metabolism of quinic, cyclohexanecarboxylic and non-phenolic aromatic acids to benzoic acid.

1. The contribution of dietary constituents to the large urinary output of benzoic acid characteristic of ruminants and some herbivores is not well understood. 2. Methods for the analysis of quinic, cyclohexanecarboxylic, benzoic, phenylacetic, 3-phenylpropionic and cinnamic acids in urine and in rumen fluids were developed. 3. The urinary output of aromatic acids by sheep given seven-rations was determined: benzoic acid output varied between 2.8 and 7.8 g/d; phenylacetic acid output between 0.16 and 1.3 g/d; cinnamic acid between 0.08 and 0.25 g/d and small amounts of 3-phenylpropionic acid were found in some samples. 4. Increments in urinary aromatic acid excretion were determined when the acids listed in paragraph 2 were infused via rumen or abomasal cannulas. 5. When cyclohexanecarboxylic acid was infused 40% of the dose was excreted as urinary benzoic acid after either route of infusion. Quinic acid was completely metabolized in the rumen; following rumen infusion between 16 and 53% of the infused acid was recovered as urinary benzoic acid; none was so recovered after abomasal infusion. 6. Urinary recoveries of rumen- and abomasally-infused aromatic acids were: benzoic acid 90 and 88% respectively as benzoic acid, phenylacetic acid 78 and 83% respectively as phenylacetic acid, 3-phenylpropionic acid 96 and 105% respectively as benzoic acid and cinnamic acid, 70 and 70% respectively as benzoic acid. 7. The concentration of aromatic acids in rumen fluid varied with time after feeding: cyclohexanecarboxylic acid was maximal (7 mg/l) 1 h after feeding, benzoic acid was always a minor component (0.5 +/- 0.5 mg/l), phenylacetic acid varied between 0 and 35 mg/l and 3-phenylpropionic acid between 25 and 47 mg/l. Cinnamic acid was not found in rumen fluid but on rumen infusion of this acid the concentration of 3-phenylpropionic acid in rumen fluid increased by 10 mg/l rumen fluid per g infused per d. 8. The incomplete metabolism of quinic and cyclohexanecarboxylic acids to urinary benzoic acid is discussed. It is concluded that the principal dietary precursors of urinary benzoic acid in ruminants are compounds yielding 3-phenylpropionic acid on microbial fermentation in the rumen. The small amount of cinnamic acid characteristic of ruminant urine arises as an intermediate in the beta-oxidation of 3-phenylpropionic acid in the body tissues.

Animal Feed↗

PubMed2004

Apical sodium-glucose co-transport can be regulated by blood-borne glucose in the ruminal epithelium of sheep (Ovis aries, Merino breed).

The intestinal Na-dependent D-glucose co-transporter (SGLT)-1 in sheep is under dietary regulation by luminal substrates. The aim of the present study was to find out whether the SGLT-1 in the forestomach of sheep is also regulated by sugars. Furthermore, the location of a possible glucosensor (luminal v. intracellular v. basolateral) was to be elucidated. Ruminal epithelia of sheep (Ovis aries, Merino breed) were pre-incubated in Ussing chambers with various substrates on the mucosal (i.e. luminal) or serosal (i.e. blood) side. This pre-incubation period was followed by a second pre-incubation period without the tested substrates (washout period). Thereafter, apical D-glucose uptake by ruminal epithelial cells was determined with 200 mumol D-[(14)C]glucose/l in the absence or co-presence of the SGLT-1 inhibitor, phlorizin. Pre-incubation with D-glucose on the mucosal side had no significant effect on apical D-glucose uptake (P>0.05). In contrast, pre-incubation with D-glucose, D-mannose, 3-O-methyl-d-glucose or sucrose on the serosal side significantly increased D-glucose uptake compared with mannitol-treated controls (P<0.05). Serosal pre-incubation with cellobiose or D-xylose had no effect. The stimulation of d-glucose uptake by serosal D-glucose pre-incubation was concentration dependent, with maximal stimulation at about 10 mmol/l. We conclude that the ruminal SGLT-1 can be up-regulated in a concentration-dependent manner by blood-borne D-glucose via an extracellular sugar-sensing mechanism.

Animals↗

PubMed1998

A review of selenium deficiency in grazing ruminants. Part 2: towards a more rational approach to diagnosis and prevention.

ESTIMATING SELENIUM STATUS: Although the importance of selenium in ruminants has been recognised for over 30 years, problems associated with selenium deficiency are still frequently identified in grazing livestock operations. There is a growing diversity of tools available for the management of selenium deficiency giving rise to diagnostic and therapeutic dilemmas for the veterinary practitioner. There is no single test for selenium adequacy which can be considered superior in all diagnostic situations because the method of choice depends on the objective of the testing procedure. REFERENCE RANGES: Reviewing the available data, the current New Zealand reference ranges for selenium concentrations in ruminant tissue and feed appear valid. CLINICAL RELEVANCE: Management of selenium deficiency will continue to be important in grazing ruminants. Practising veterinarians should be familiar with the appropriate use of tests for selenium deficiency. Advice should be based on micronutrient analysis of animal tissue, defensible reference ranges backed by production response data, and supplementation programmes which optimise the return on investment.

Journal Article↗

PubMed2005

Getting unstuck: the roles of hope, finding meaning, and rumination in the adjustment to bereavement among college students.

The relationships between hope, bereavement-related rumination, and finding meaning (making sense and benefit finding) were examined in 158 college students who experienced the death of a loved one within the latter half of their lives. Greater rumination was related significantly to lessened psychological well-being, and it mediated the relationship between being able to make sense of the death and superior well-being. Finding benefits in bereavement was associated with positive adjustment for those who recently experienced the death of a loved one, whereas it was related to negative adjustment for those who experienced the death longer ago. Higher hope predicted greater well-being, but it was not related to rumination or finding meaning.

Adaptation, Psychological↗

PubMed2006

Investigations on the effect of the ruminal N-balance on rumen metabolism, urea content in blood serum and milk as well as some liver parameters of lactating cows.

Seven dairy cows fitted with ruminal and duodenal cannulae were used to investigate the influence of the amount of ruminally available N (Ruminal N-Balance, RNB) on the rumen metabolism and to answer the question on the lowest N-amount in the rumen, without negative effects on the fermentation. Animals were fed a ration on the basis of 7.9 kg corn silage and 7.2 kg concentrates related to dry matter, intended to meet the animals mean NEL and protein requirements. RNB amounted to -0.6 g/MJ ME in the basis ration. The other 3 rations were adjusted to RNB-values of -0.3, 0 and + 0.3 g/MJ ME by urea supplements in the concentrates. The increase in RNB resulted in higher NH3-N concentrations in the rumen fluid and in the duodenal digesta and higher urea concentrations in the blood and milk. The significantly highest amount of protein at the duodenum was detected when RNB showed an equilibrium (RNB = 0). The efficiency of microbial protein (MP) synthesis (gMP/kg fermented organic matter) was the same, g MP/d and g MP/MJ ME were significantly lower with RNB = -0.6g/MJ ME as compared to RNB = 0. The group with thelowest RNB showed the highest level of feedprotein degradation as well as the lowest organic matter, NDF and ADF fermentation. An effect on cholesterol, total bilirubin and gammaGT due to different RNB was not detected. The activities of GLDH and AST were highest when the RNB was -0.6 g/MJ ME. From the results, it can be concluded that significantly negative effects on rumen fermentation occur when RNB-values are below -0.3 g/MJ ME. However, a positive RNB did not increase t he degradation and synthesis capacity of the rumen micro-organisms as compared to RNB = 0.

Ammonia↗

PubMed1976

[Histological studies on cow intestinal mucosa and electron microscopic studies of the ruminal epithelium of cows fed a deficient diet for a prolonged time].

Histological and histochemical studies were carried out on the gastro-intestinal mucosa of three experimental cows (roughages/maize silage) and three control animals. The animals were slaughtered on termination of the long-term trial. Mucosa samples were taken, for further study, from the rumen, the duodenum, the jejunum, the large intestine and the appendix. Histochemical analysis did not reveal any essential differences in the activities of non-specific esterase, alkaline and acid phosphatase and lactic acid dehydrogenase in the mucosa of the rumen, the large and the small intestine and the appendix of both the experimental animals and the controls. The experimental animals were found to exhibit a higher rate of glutamate-dehydrogenase activity in the ruminal mucosa and in the mucosa of the large and small intestine. A higher succinate dehydrogenase activity was observed in the ruminal mucosa of the experimental animals, relative to that of the controls, while the activity in the intestinal mucosa was decreased. Only slight changes were noted in the activity of the enzymatic systems tested. Electron microscopic studies did not reveal any differences in the ultrastructure of the epithelial cells of the ruminal mucosa in both the experimental animal and the controls.

Acid Phosphatase↗

PubMed1977

[The effect of nutritional factors on the ruminal mucosa. 3. Condition of the mucosa after infusion of propionic acid, acetic acid and butyric acid].

Three non-lactating cows (Deutsches Schwarzbuntes Rind) with large ruminal fistulas were fed coarsely structured food. Within a trial period of 21 weeks infusion periods lasting 3 weeks alternated with equally long control periods (K). During the 3 infusion periods, 8.4 mMol of propionic acid (P), 14.8 mMol of acetic acid (E) and 4,5 mMol of butyric acid (B) per kg liveweight per day were administered through the fistula, the total quantity being 19 litres of solution. In the periods K1...4 the ruminal fluid contained an average of 68 Mol% E, 19 Mol% P, 13 Mol% B (maximum of 10.25 mMol free fatty acids (FFS) per 100 ml, minimum pH 6.4). In the course of the 10 hrs of infusion the Mol percentages of the particular acids infused increased to 27% P (maximum of 11.14 mMol FFS per 100 ml, minimum pH 6.4) or 79% E (maximum of 12,99 mMol FFS per 100 ml, minimum pH 6.0 (5.5)) or 25% B (maximum of 10.34 mMol FFS per 100 ml, minimum pH 6.0 (5.5)). Infusions of E and B had the most pronounced effect on the ruminal mucosa compared with the K periods. All fatty acids increased the process of keratinization and decreased the size of cell nuclei in the stratum basale. As specific effect, P infusions produced a thickening of the lamina propria; B infusions caused a thickening of the stratum germinativum (proliferative effect) while e infusions led to a drastically reduced thickness of villi (antiproliferative effect) due to reductions in the stratum germinativum and the lamina propria. According to the morphological situation high specific mucosal function is suggested during the B-period. The mucosa appeared quite normal during all periods investigated, with the exception of the E period, where hyperkeratosis, atrophy and necrosis were observed in 34% of the sample. Changes in the state of the mucosa appeared as early as 1 week after the beginning of the respective trial periods. Keratin consolidation was the primary cause for chemically induced keratosis. The development of hyperkeratosis seemed to be favoured if low pH values occurred in the rumen in combination with small amounts of metabolites inducing proliferation, both representing synergistic factors.

Acetates↗

PubMed1986

Anatomical studies into the ruminal mucosa of pygmy goats in relation to their age.

The ruminal mucosa of 15 pygmy goats of different age (Z1 approximately 4-5 months, Z2 approximately 1 year, Z3 approximately 1.5-5 years) were studied gross-anatomically concerning their colour, clumping of papillae, fodder precipitations on the papillae, areas poor in papillae or devoid of them and the development of papillae. The density of papillae/cm2 in the 3 groups investigated was 79.4; 67.3; 58.0; the mean length of the papillae (mm) 1.75; 1.86; 2.96; the mean breadth of the papillae (mm) 1.3; 1.2; 2.0; the area of the ruminal mucosa (cm2) 799; 943; 1 195; the area of the ruminal pillars (cm2) 38; 41; 69; the number of the papillae/rumen 59,940; 58,022; 64,782; the total absorptive area (cm2) 3,802; 3,854; 11,268; the surface magnifying factor 4.0; 3.4; 8.4.

Aging↗

PubMed1993

[Ruminal nitrogen metabolism in calves and sheep. 3. Effect of hay-concentrate ratio in calves].

During the milk feeding period (ca. 55th day of life) and 2 weeks after the milk feeding period (ca. 80th day of life) the influence of a hay quota in the ration (on DM basis) of 6, 10, 14 and 18% in the milk feeding period and of 16, 23, 31 and 37% in the period after milk feeding was tested as to ruminal N metabolization with calves supplied with duodenal re-entrant cannulae. The increase of the hay quota in the ration for ruminating calves reduced as a tendency duodenal NAN passage, its bacterial N-quota, post-ruminal NAN digestibility and, due to a worse utilization of available N for bacterial N-synthesis, bacterial N-synthesis rate. The apparent fermentation of organic matter was, as a tendency, increased with the growing hay quota in the ration.

Animal Feed↗

PubMed2004

Bilayer tablets based on poly (epsilon-caprolactone) and polymethylmethacrilates as controlled-release systems for ruminants.

Rumen-stable devices ensure a protection of active ingredients against chemical degradation and bacterial fermentation processes that occur in the rumen. These systems should also provide postruminal bioavailability and controlled release of the active ingredient. The objective of this study was the preparation of bilayer tablets as rumen-stable delivery systems, designed for the oral administration of active ingredients (folic acid) to ruminants. The tablets are composed of two layers: layer A ("high-density layer") constituted by poly (epsilon-caprolactone) mixed with iron powder and characterized by sufficient density to avoid rumination; layer B ("release layer"), containing folic acid (25 mg), poly (epsilon-caprolactone) or polymethylmethacrylates (Eudragit RS and RL) designed to be rumen-stable and to target a controlled release of folic acid in the intestinal tract. In vitro rumen-protection tests were performed in buffer systems at pH 5.5 and pH 2.0, simulating a ruminal and abomasal environment, to verify the stability of bilayer tablets at these conditions. In vitro release tests were carried out in phosphate buffer at pH 7.4, to study the release behavior of the dosage forms in the intestinal environment. A preliminary in vivo test was carried out with radiographic images made after administration of the tablets to sheep, to evaluate their capacity to be retained in the reticulum-rumen. The amount of iron powder used provides a density of about 2.3 g/cm3 to the whole tablet. The tablets having layer B constituted by poly (epsilon-caprolactone) or Eudragit RS do not disintegrate in buffer media at pH 5.5 and pH 2.0, and they are characterized by a sustained release at pH 7.4. Radiological preliminary tests show that these prepared bilayer tablets are able to be retained in the reticulum-rumen tract of the sheep.

Acrylic Resins↗

PubMed2002

Kinetics of ruminal degradation of wheat and potato starches in total mixed rations.

Wheat and potato are rich in starch but their starches differ in their rate of ruminal degradation. Kinetics of in sacco disappearance and profiles of ruminal fermentation were studied for these two concentrates in total mixed rations based on grass silage or corn silage. Wheat starch was more rapidly (34%/h) degraded by rumen microorganisms than potato starch (5%/h). The differences in starch degradation in sacco were found again in the VFA concentrations, mainly in grass silage-based diets. Overall ruminal pH, total VFA concentration, and proportions of acetate, propionate, and butyrate are more variable for wheat during the kinetic (amplitude and quickness) than for potato in grass silage-based diets. In these diets, risks of acidosis were more elevated with wheat than with potato but the VFA concentrations were also higher. These differences of fermentation profile were so reduced in corn silage-based diets that, in this case, wheat can be substituted by potato without any effect on digestion and no risk of acidosis.

Acidosis↗

PubMed1990

Zoonotic potential of giardiasis in domestic ruminants.

This study was conducted to assess the prevalence and zoonotic potential of giardiasis in domestic ruminants. Prevalence of infection was 17.7% in sheep and 10.4% in cattle and was significantly higher in lambs and calves (35.6% and 27.7%, respectively). Naturally infected lambs released cysts intermittently for months. Giardia trophozoites from sheep had typical claw hammer-shaped median bodies and were successfully cultured in TYI-S-33 medium, and cytosolic, cytoskeletal, and membrane fractions exhibited protein profiles similar to human isolates (WB). Immunoblotting showed that sera from infected sheep recognized human Giardia, sera from patients with giardiasis recognized Giardia from sheep, and in both cases recognition involved antigenic proteins of similar molecular weight. Cyst output and clinical signs in ovine infection resemble human disease and the organisms infecting humans and ruminants are morphologically and antigenically similar. It is postulated that domestic ruminants may be a reservoir for human infection and vice versa, thus classifying giardiasis as a zooanthroponotic disease.

Alberta↗

PubMed1983

Effects of avoparcin on ruminal propionate production and amino acid degradation in sheep fed high and low fiber diets.

The effect of the antibiotic, avoparcin, on ruminal propionate production and amino acid degradation was investigated by using four rumen fistulated wethers. Wethers were fed each of four diets during 28-day periods in a 4 X 4 Latin square design. Diets were high fiber (HF), high fiber plus 50 ppm avoparcin (HF-AVO), low fiber (LF) and low fiber plus 50 ppm avoparcin (LF-AVO). Total digestible energy intake (1.25 X maintenance) and crude protein intake for each animal were similar for all diets. Propionate production was determined each period from all animals by using a single injection of [1-14C]propionate and polyethylene glycol. Avoparcin decreased total volatile fatty acid concentration, increased ruminal pH and molar proportions of propionate on both HF and LF diets. Daily propionate production and pool turnover rate increased in sheep fed LF-AVO. Similar changes were noted in HF-AVO animals, although they were not statistically significant. Avoparcin decreased ruminal ammonia (50 vs. 45 mg/100 ml) and increased alpha amino nitrogen (8.6 vs. 14.3 mM) in LF-fed sheep. In vitro studies demonstrated a decreased degradation of crystalline amino acids by mixed populations of rumen microorganisms from sheep receiving LF diets containing avoparcin. Avoparcin appears to modify rumen fermentation by increasing propionate production and inhibiting protein or amino acid degradation.

Amino Acids↗

PubMed1984

Activities of enzymes related to NADPH generation and amino acid metabolism in the ruminal mucosa of sheep.

Experiments were performed with growing lambs to investigate dietary influences on enzymes involved in the metabolism of propionate, amino acids and NADPH in the ruminal mucosa. Glutamate dehydrogenase (GDH) was the only enzyme assayed that was consistently affected by diet. First, lambs were fed either rolled barley, resulting in epithelial hyperkeratosis, or whole unprocessed barley, resulting in keratin aplasia and reduced GDH activity. Secondly, lambs were fed isonitrogenous diets containing either fish meal or urea. GDH activity was greater when fish meal was fed. NADP-isocitrate dehydrogenase was more active than other NADPH-generating enzymes in ruminal mucosa and several other lamb tissues, but the operation of the isocitrate cycle in rumen epithelium may be restricted by a low activity of aconitate hydratase. These results suggest that enzyme activities in ruminal mucosa are generally unresponsive to diet and that adaptations in GDH are related to changes in rumen morphology, rather than to isocitrate cycle activity or ammonia assimilation.

Amino Acids↗

PubMed1996

Ruminal microbial metabolism of peptides and amino acids.

Peptides and amino acids, either present in the diet or arising from proteolysis in the rumen, are potential nutrients for the growth of ruminal microorganisms but also are liable to be degraded to ammonia and lost from the rumen. In both cases, peptides generally are metabolized by the mixed population more rapidly than amino acids. The predominant mechanism of peptide degradation is biphasic, via dipeptidyl peptidases, which cleave dipeptides from larger peptides followed by the action of dipeptidases. Peptides blocked at the N-terminus, or with glycine or proline as the N-terminal or penultimate N-terminal residue, are more slowly degraded than others. Dipeptidyl peptidase activity occurs only in Prevotella ruminicola among the common ruminal microbial species. In contrast, dipeptidase is present in many species, including P. ruminicola, and is particularly high in ruminal protozoa. Deamination of amino acids is carried out by a combination of numerous low activity bacteria and protozoa and a much smaller number of high activity species. Ammonia production is probably carried out mainly by the low activity species, which again include P. ruminicola, but proliferation of the high activity species may be a problem when certain diets are fed. Excessive ammonia production can be controlled by ionophores, which slow peptide metabolism, suppress growth of the high activity deaminating bacteria and cause the residual ionophore-resistant population to break down amino acids more slowly.

Amino Acid Sequence↗

PubMed1986

Manometric study of a ruminator.

Rumination is an uncommon disorder with controversial pathophysiology. We have studied a classic ruminator with esophageal, gastric, and small bowel motility techniques during episodes of voluntary regurgitation. His regurgitation was accompanied by simultaneous positive pressure deflections in multiple locations in the stomach, simultaneous negative pressure deflections in multiple locations in the esophagus followed rapidly by simultaneous positive pressure deflections, brief (1-second) periods of lower esophageal sphincter relaxation, and deep inspiratory movements. No intrinsic abnormalities of esophageal, gastric, or small bowel motility were present. We conclude that regurgitation in a ruminator is triggered by a Mueller experiment (forced inspiration against a closed glottis).

Adult↗

PubMed1988

Gastrointestinal nematode parasites and the stability and productivity of intensive ruminant grazing systems.

This paper uses mathematical models, describing the transmission dynamics of directly transmitted gastrointestinal nematode parasites of sheep and cattle, to examine the impact of these parasites on the stability and productivity of ruminant grazing systems. Current models of the ecology of grass growth under grazing, and the epidemiology of trichostrongylid nematode parasites of ruminants, are combined in a formulation that captures the general features of the plant - (ruminant) herbivore - parasite interaction. The simplest case, in which herbivore numbers are constant and not food limited (the norm for many agricultural systems) is considered in detail. The effect of gastrointestinal parasitism in reducing herbivore feeding rates is shown to act as a potential density-dependent constraint on the parasite's infection rate. The process is manifested in the model as a progressive linearization of the relation between herbivore feeding rate and plant density at the parasite equilibrium. This effect acts to stabilize the dynamics of the model grazing system and significantly affects its predictions about the impact of parasite control and the pattern of host productivity. Model predictions are discussed in the light of relevant field observations, and areas for future research are identified.

Animal Feed↗