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PubMed1990

Energy metabolism reactions in ruminant muscle: responses to age, nutrition and hormonal status.

Energy expenditure in muscle comprises reactions related to intermediary metabolism and those of posture and activity. The metabolic reactions respond to a wide range of nutritional and hormonal stimuli and are often apparently co-ordinated; in magnitude, however, their contribution to energy requirements can be minor compared with locomotion and posture. Metabolic reactions include protein turnover, ion transport and substrate cycles. In young ruminants muscle protein synthesis responds to intake but effects on energy expenditure are less pronounced; the situation with the adult is unclear. The involvement of insulin in ruminants may differ from that in monogastrics but effects are observed with thyroid hormones. Ruminant muscle may have a higher energy requirement for Na+, K+ transport which responds in proportion to total oxygen uptake to alterations in intake. Thyroid hormone treatment and, probably, the catecholamines enhance both Na+, K+ and Ca2+ transport. Muscle has fewer substrate cycles than liver and each may contribute only 1-3% toward oxygen consumption. Several are sensitive to insulin, but larger responses are observed with thyroxine and epinephrine and under stress conditions, therefore, may account for significant proportions of heat increment. Energy costs of standing may be considerable and posture movements may change with diet quality and quantity. Locomotory activity may mask changes in the contribution of metabolic reactions in response to different stimuli. Approximately 80% of energy costs for muscle in vivo are accounted for by protein turnover (20-25%), ion transport (25-30%), substrate cycling (5-8%) and standing (30%). Better integration of experiments in vivo and in vitro is required to improve the quantification and resolve data anomalies.

Aging↗
PubMedDate not supplied

Effect of nutritional factors on biochemical, structural and metabolic characteristics of muscles in ruminants, consequences on dietetic value and sensorial qualities of meat.

Ruminant meat is an important source of nutrients and is also of high sensory value. However, the importance and nature of these characteristics depend on ruminant nutrition. The first part of this review is focused on biochemical and dietetic value of this meat. It offers a panel of quantitative and qualitative contributions, especially through its fatty acids characteristics. Since saturated and trans-monounsaturated fatty acids are considered as harmful to human health, their amount in muscles can be reduced by increasing the proportions of dietary polyunsaturated fatty acids (PUFA) absorbed by the animals. On the contrary, some fatty acids (n-6 and n-3 PUFA, conjugated linoleic acid) specifically incorporated in muscle tissues would play a favourable role in the prevention or reduction of major diseases in human (cancers, atherosclerosis, obesity) and therefore be recommended. The second part of this review treats different aspects of the sensorial qualities of meat. Skeletal muscle structure and its biochemical components influence muscle transformation to meat and sensorial qualities including tenderness, colour, flavour and juiciness. This paper shows how nutrition can influence, in ruminants, metabolic activity as well as muscle structure and composition, and thereby affect meat quality.

Animal Nutritional Physiological Phenomena↗
PubMed1997

Recent developments and potentialities for reducing embryo mortality in ruminants: the role of IFN-tau and other cytokines in early pregnancy.

This review considers the potential reduction of embryo mortality in vitro and in vivo in ruminants. Data on cytokines provided by different fields of reproductive immunology and biology were collated. Because of the crucial importance of the local interactions between the embryo and its dam, the expression of growth-factor and cytokine genes was analysed in the embryo proper, trophoblast, oviduct and endometrium by reverse transcriptase polymerase chain reaction in sheep and in cattle during the pre- and periimplantation periods. Many deleterious cytokines, such as tumour necrosis factor-alpha, interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and beneficial cytokines, such as transforming growth factor-beta, leukaemia inhibiting factor, colony-stimulating factor-1 (CSF-1), granulocyte-macrophage CSF, IL-1, IL-3, IL-4, IL-6, IL-10 and IFN-tau appeared to be involved in embryo survival in ruminants and other species. Their administration is efficient in a murine experimental model (CBA/J x DBA/2) of embryonic and fetal mortality. For instance, recombinant ovine IFN-tau (roIFN-tau) injected at the moment of implantation drastically reduces embryonic mortality in this model. In ruminants, roIFN-tau and recombinant bovine IFN-tau are very efficient in maintaining progesterone luteal secretion in cyclic animals. The involvement of IFN-tau in the mechanisms of maternal pregnancy recognition are particularly detailed in relation to inhibition of 13,14 dihydro-15-keto-prostaglandin F2 alpha (PGFM) pulses and oxytocin uterine receptivity. A synthetic model of the anti-luteolytic effects of IFN-tau on the endometrial cell is proposed. Finally, the particular potential of serum pregnancy-specific proteins (PSPs: PSPB, PSP60, pregnancy-associated glycoprotein) for monitoring embryo survival, with examples given for cattle and sheep is underlined.

Amino Acid Sequence↗
PubMed2002

A deer (subfamily Cervinae) genetic linkage map and the evolution of ruminant genomes.

Comparative maps between ruminant species and humans are increasingly important tools for the discovery of genes underlying economically important traits. In this article we present a primary linkage map of the deer genome derived from an interspecies hybrid between red deer (Cervus elaphus) and Père David's deer (Elaphurus davidianus). The map is approximately 2500 cM long and contains >600 markers including both evolutionary conserved type I markers and highly polymorphic type II markers (microsatellites). Comparative mapping by annotation and sequence similarity (COMPASS) was demonstrated to be a useful tool for mapping bovine and ovine ESTs in deer. Using marker order as a phylogenetic character and comparative map information from human, mouse, deer, cattle, and sheep, we reconstructed the karyotype of the ancestral Pecoran mammal and identified the chromosome rearrangements that have occurred in the sheep, cattle, and deer lineages. The deer map and interspecies hybrid pedigrees described here are a valuable resource for (1) predicting the location of orthologs to human genes in ruminants, (2) mapping QTL in farmed and wild deer populations, and (3) ruminant phylogenetic studies.

Animals↗
PubMed1984

Influence of monensin and lasalocid on mineral metabolism and ruminal urease activity in steers.

Growing steers were used in a replicated 3 X 3 Latin square to study the influence of ionophores on mineral metabolism and ruminal urease activity. Treatments consisted of: 1) basal high energy diet; 2) basal plus 33 ppm lasalocid and 3) basal plus 33 ppm monensin. Each period was 33 days and apparent absorption and retention of macrominerals were measured during the last 5 days of each period. Mineral intake during the collection period was not affected by treatment. Both ionophores increased apparent absorption of sodium, magnesium and phosphorus. Retention of magnesium and phosphorus were higher for steers receiving either lasalocid or monensin. Potassium and calcium absorption were not significantly affected by treatment. Serum concentrations of macrominerals were similar for all treatments. Zinc and copper concentrations in serum were higher in animals fed monensin or lasalocid. Steers fed either ionophore had lower concentrations of soluble potassium and calcium in rumen fluid. Both ionophores also decreased ruminal osmolality. Bacterial urease, a nickel-dependent enzyme, was decreased by 28 and 66% in animals that received lasalocid and monensin, respectively. These findings indicate that lasalocid and monensin affect metabolism of certain minerals in ruminants.

Animals↗
PubMed1992

Metabolism of nitrogenous compounds by ruminant liver.

Ruminants absorb substantial amounts of ammonia nitrogen and very little glucose. Ammonia absorbed is removed by the liver and converted to urea, which can be recycled to the digestive tract and add to the pool of ammonia absorbed. When ammonia absorption and liver urea production are increased by changes in nitrogen intake, an associated increase in liver alpha-amino nitrogen removal has been observed. Reasons for the increase in liver removal of amino acids with greater ureagenesis are uncertain, but the aspartate/glutamate requirement of ureagenesis and the complex relationships between ureagenesis and the tricarboxylic acid cycle, glucogenesis, liver energy metabolism and redox state all may be involved. Amino acids represent potential sources of carbon for liver glucogenesis and precise reckonings of the contributions of amino acid carbon to glucogenesis are needed for ruminants fed differing diets. There is evidence for the involvement of peptides in liver nitrogen exchanges and amino acids in peptides represent a potential source of carbon for glucogenesis and nitrogen for ureagenesis. A number of endocrine factors have an impact on liver nitrogen metabolism in ruminants. Growth hormone decreases liver urea release and increases liver glutamate release.

Amino Acids↗
PubMed1994

The role of dietary fats in efficiency of ruminants.

Fat increases energetic efficiency in lactating cows by increasing total energy intake, by generating ATP more efficiently (ATP/unit energy expended) than volatile fatty acids or protein, by direct incorporation into product, and by promoting nutrient partition toward milk production. Factors that limit utilization of large amounts of fat by ruminants include inhibitory effects on ruminal fermentation, lower intestinal absorption at high intake, low contribution to total oxidation of nutrients, and sensitivity to nutrient imbalance, causing reduced energy intake. Research has resolved many problems associated with effects on ruminal fermentation; research in the future may improve fat digestibility and reduce limits of oxidation. Effect of high fat on regulation of feed intake has received little attention.

Animals↗
PubMed1996

Effect of rumen protozoa on nitrogen utilization by ruminants.

Results obtained during the past decade indicate clearly that protozoa are actively involved in the degradation of dietary and microbial proteins in the rumen. Because of the great ability of protozoa to ingest the particulate matter suspended in the rumen, protozoa are more active in degrading insoluble than soluble proteins. This indicates that studies carried out using lysed and sonicated protozoa are not appropriate for quantifying the actual contribution of protozoa to protein degradation in the rumen. In vivo trials have confirmed that duodenal flow of both undegraded dietary protein plus bacterial protein generally is increased by defaunation. The decrease in ruminal ammonia concentration consistently observed after defaunation accounts for the lower urinary nitrogen (N) excretion found in defaunated animals, whereas the increase in fecal N excretion in the same animals probably results from a shift of plant cell wall digestion from the rumen to the large intestine. Total N excretion is not altered significantly by defaunation. A summary of literature data indicates there are contradictory effects of defaunation on ruminant performance. This implies that animal response to defaunation may depend on the specific nutrient-limiting performance on the one hand and on the modifications of digestion and metabolism resulting from defaunation on the other. Different methods are proposed to either eliminate or decrease the numbers of ruminal protozoa or to alter their makeup. However, none of these approaches has been tested under practical feeding conditions.

Animals↗
PubMed2004

The evolution of phylogenetic differences in the efficiency of digestion in ruminants.

This study investigates, for the first time (to our knowledge) for any animal group, the evolution of phylogenetic differences in fibre digestibility across a wide range of feeds that differ in potential fibre digestibility (fibre to lignin ratio) in ruminants. Data, collated from the literature, were analysed using a linear mixed model that allows for different sources of random variability, covariates and fixed effects, as well as controlling for phylogenetic relatedness. This approach overcomes the problem of defining boundaries to separate different ruminant feeding styles (browsers, mixed feeders and grazers) by using two covariates that describe the browser-grazer continuum (proportion of grass and proportion of browse in the natural diet of a species). The results indicate that closely related species are more likely to have similar values of fibre digestibility than species that are more distant in the phylogenetic tree. Body mass did not have any significant effect on fibre digestibility. Fibre digestibility is estimated to increase with the proportion of grass and to decrease with the proportion of browse in the natural diet that characterizes the species. We applied an evolutionary model to infer rates of evolution and ancestral states of fibre digestibility; the model indicates that the rate of evolution of fibre digestibility accelerated across time. We suggest that this could be caused by a combination of increasing competition among ruminant species and adaptation to diets rich in fibre, both related to climatically driven environmental changes in the past few million years.

Animals↗
PubMed1994

Cloning of the nucleocapsid protein gene of peste-des-petits-ruminants virus: relationship to other morbilliviruses.

Two independent cDNA clones, identified as representing the mRNA of the nucleocapsid protein gene of peste-des-petits-ruminants virus, were sequenced. The longest insert was 1662 nucleotides, not counting the poly(A) tail, and it was estimated that about 21 nucleotides were missing from the complete gene sequence. The sequence contained one long open reading frame encoding a protein of 525 amino acids with a predicted relative molecular mass of 58,008. Comparisons of the nucleic acid and protein sequences of all the morbillivirus nucleoproteins so far determined indicated two major subgroups in the morbillivirus genus of the Paramyxoviridae: one group included canine and phocine distemper viruses, and the other rinderpest, measles and peste-des-petits-ruminants viruses. Peste-des-petits-ruminants virus was found to be slightly more related to canine and phocine distemper viruses than were measles and rinderpest viruses.

Amino Acid Sequence↗
PubMed2005

A novel subgroup of rhadinoviruses in ruminants.

In the course of investigating the malignant catarrhal fever (MCF) subgroup of rhadinoviruses, seven novel rhadinoviruses were identified in a variety of ruminants, including domestic sheep, bighorn sheep, bison, black-tailed deer, mule deer, fallow deer, elk and addax. Based on the DNA polymerase gene sequences, these newly recognized viruses clustered into a second distinct subgroup in ruminants with three members identified previously in cattle, goats and oryx. Phylogenetic analysis revealed that the currently known ruminant rhadinoviruses appear to comprise three distinct genetic lineages: (i) the MCF subgroup, defined by sequence identity and the presence of the 15A antigenic epitope; (ii) a second distinct subgroup, devoid of the 15A epitope, which contains the previously reported bovine lymphotropic herpesvirus and related viruses; and (iii) a third distinct subgroup represented by Bovine herpesvirus 4. Comparison of phylogenetic trees between the rhadinoviruses and their corresponding hosts further supports the gammaherpesvirus and host co-evolution theory.

Animals↗
PubMed2004

Effects of several inhibitors on pure cultures of ruminal methanogens.

AIMS: To examine the effects of five inhibitors of methanogenesis, 2-bromoethanesulphonate (BES), 3-bromopropanesulphonate (BPS), lumazine, propynoic acid and ethyl 2-butynoate, on CH4 production of the ruminal methanogens Methanobrevibacter ruminantium, Methanosarcina mazei and Methanomicrobium mobile. METHODS AND RESULTS: Methanogens were grown in MS medium including 25% (v/v) clarified ruminal fluid. Methane production was measured after 4 and 6 days of incubation. Methanobrevibacter ruminantium was the most sensitive species to BES, propynoic acid and ethyl 2-butynoate. Methanosarcina mazei was the least sensitive species to those chemical additives, and Mm. mobile was intermediate. BPS failed to inhibit any of the methanogens. All three species were almost completely inhibited by 50- and 100%-lumazine saturated media, but the inhibition was somewhat lower with a 25%-lumazine saturated media. CONCLUSIONS: There were important differences among species of methanogens regarding their sensitivity to the different inhibitors. In general, Ms. mazei was the most resistant to inhibitors, Mb. ruminantium the least resistant, and Mm. mobile was intermediate. SIGNIFICANCE AND IMPACT OF THE STUDY: Differences among methanogens regarding their resistance to chemical inhibitors should be considered when designing strategies of inhibition of ruminal methanogenesis, as selection of resistant species may result.

Alkanesulfonic Acids↗
PubMed1992

Evolution of ruminant hemoglobins. Thermodynamic divergence of ox and buffalo hemoglobins.

The ligand-binding properties of hemoglobins from two homozygote phenotypes (AA and BB) of water buffalo (Bubalus bubalis) have been characterized by equilibrium and kinetic techniques. In the case of the BB phenotype, the two constituent hemoglobins have been purified and separately analysed. Buffalo hemoglobins display the reduced sensitivity to organic phosphates characteristic of ruminant hemoglobins, their physiological effector probably being the chloride ion. In contrast to the other known hemoglobins from ruminants, all the hemoglobins from the water buffalo display a significant temperature sensitivity, the delta H for oxygen binding in the presence of physiological effectors approaching that of human hemoglobin (delta H = -30.5 kJ/mol O2). This discrepancy with the other ruminant hemoglobins (e.g. ox, delta H = -10.4 kJ/mol O2), whose primary structure is very similar to that of buffalo, hemoglobins might be correlated to the different habitat and phylogenetic history of the two subfamilies (Bos and Bubalus) of Bovidae.

Animals↗
PubMed1995

Inhibition of ruminal staphylococci and enterococci by nisin in vitro.

A collection of 59 ureolytic and lactic acid-producing ruminal staphylococci and enterococci, isolates from domestic and wild ruminants, were tested for sensitivity or resistance to lantibiotic nisin. All strains tested were sensitive with zones of inhibition, around wells containing 250 micrograms nisin, from 6 to 26 mm. 74.6% of isolates had zones of inhibition more than 10 mm and 11.1% more than 20 mm. Nisin was more effective against enterococci than staphylococci. Sensitivity of ruminal isolates to nisin may be used to control bacterial growth during the colonization of the rumen or to study the role of antibacterial activity in microbial interactions. Results obtained can be also used in experiments on gnotobiotic animals.

Animals↗
PubMed1994

The struggle to maintain hydration and osmoregulation in animals experiencing severe dehydration and rapid rehydration: the story of ruminants.

Ruminants in tropical and desert areas routinely experience cycles of severe dehydration and rapid rehydration. These animals can withstand severe dehydration (18-40% of initial body weight), which exceeds considerably the capacity of most monogastric mammals. This capacity is related to their ability to use, during the course of dehydration, their large water reservoir in the rumen, which contributes 50-70% of the total water loss. As rumen fluid is in approximate isotonicity with systemic fluid, the utilization of gut water during the course of dehydration involves a considerable load of sodium and potassium. Consequently, the effectiveness of utilization of rumen fluid during dehydration depends on the capacity of the kidney to 'desalt' the water absorbed from the gut and on maintenance of salivary flow to the rumen. Following rehydration, ruminants can imbibe their entire water deficit in one drinking and the entire amount ingested is first retained in the rumen. The rumen volume at this stage may exceed the extracellular fluid volume and the sudden drop in rumen osmolality creates a huge osmotic gradient (200-300 mosmol kg-1) between the rumen and systemic fluid. Ruminant animals are confronted at this stage by two opposing tasks, each of them of vital importance: (i) the need to prevent the osmotic hazard leading to water intoxication; and (ii) the need to retain the ingested water, so that it is not missing for the next dehydration cycle. The most prevalent view until recently was a theory which attributes an osmotic protective mechanism to the rumen wall. However, such a capacity has not yet been demonstrated and is challenged by contradictory observations that large amounts of water are absorbed from the rumen following rehydration. The view that is most consistent with available information is that gustatory-alimentary and hepatoportal signals regarding the presence of large amounts of water in the rumen and the absorption of water from the gut activate a range of homeostatic responses involved in fluid and sodium restitution. The efferent elements, presumably activated by the CNS, include: a dramatic increase in secretion of hypotonic saliva and, reciprocally, a dramatic drop in urine flow. The enhanced saliva secretion recycles a considerable portion of the water absorbed from the gut back to the rumen, which allows effective retention of water while avoiding the danger of osmotic threat to the red blood cells. The enhanced saliva secretion also drains large amounts of sodium and bicarbonate from the blood. Accompanying responses are marked retention of sodium and carbonic acid in the kidney.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1969

Reticulo-ruminal mechanoreceptors in sheep.

1. The nervous activity in single afferent gastric vagal units was recorded electrophysiologically from halothane-anaesthetized sheep with spontaneous reticulo-ruminal movements present.2. Sixty-six afferent units innervating gastric mechanoreceptors were isolated from fifteen sheep. The receptors were located mainly in the medial walls of the reticulum and the cranial sac of the dorsal rumen, and also in the reticular groove, the reticulo-ruminal fold, the dorsal and ventral sacs of the rumen and the omasal canal.3. The mean conduction velocity (C.V.) for twenty-seven units was 12.4 +/- 1.0 m/sec (S.E.). For units with a pathway in the dorsal vagal trunk, the mean C.V. was 14.5 +/- 1.0 m/sec (S.E.) and for units with a pathway in the ventral vagal trunk the mean C.V. was 6.6 +/- 0.5 m/sec (S.E.).4. From the receptors a slowly adapting response was elicited by tangential lengthening. These were tension receptors in series with contractile elements, as they were excited by increased tensions developed both passively by inflation of the viscus and actively by muscular contractions.5. Receptors in the reticulum and the rumen appeared to be situated deep in the muscle layers, whereas those in the reticular groove structures seemed to be more superficial and gave the in series tension receptor response as well as a response to light pressure.6. A resting discharge in tension receptor units was usually absent at low levels of distension but appeared and increased as the level of distension was raised. Intermittency and fluctuations in the resting discharge were related to intrinsic local movement involving the receptive fields. Increasing distension enhanced the intrinsic movements.7. Even after the removal of the abomasum, reticular and ruminal (primary cycle) movements were evoked by distending the reticulum. It is possible that this manoeuvre enhanced intrinsic movements, which, in turn, caused an increased excitatory afferent input to the ;gastric centres' from in series reticular tension receptors.8. The enhanced afferent discharge from reticular tension receptors elicited by an isometrically recorded reticular contraction reflexly inhibited the subsequent (primary cycle) contraction of the rumen.9. Very few receptors were located in the caudal regions of the rumen whereas the cranial sac is richly supplied with tension receptors. The idea that the cranial sac may serve as the reflexogenic zone for secondary cycle movements of the rumen is discussed.

Animals↗
PubMed2006

Quantitative PCR method for sensitive detection of ruminant fecal pollution in freshwater and evaluation of this method in alpine karstic regions.

A quantitative TaqMan minor-groove binder real-time PCR assay was developed for the sensitive detection of a ruminant-specific genetic marker in fecal members of the phylum Bacteroidetes. The qualitative and quantitative detection limits determined were 6 and 20 marker copies per PCR, respectively. Tested ruminant feces contained an average of 4.1 x 10(9) marker equivalents per g, allowing the detection of 1.7 ng of feces per filter in fecal suspensions. The marker was detected in water samples from a karstic catchment area at levels matching a gradient from negligible to considerable ruminant fecal influence (from not detectable to 10(5) marker equivalents per liter).

Animals↗
PubMed2006

Biotic and abiotic factors influencing in vitro growth of Escherichia coli O157:H7 in ruminant digestive contents.

The gastrointestinal tract (GIT) of ruminants is the main reservoir of enterohemorrhagic Escherichia coli, which is responsible for food-borne infections in humans that can lead to severe kidney disease. Characterization of biotic and abiotic factors that influence the carriage of these pathogens by the ruminant would help in the development of ecological strategies to reduce their survival in the GIT and to decrease the risk of contamination of animal products. We found that growth of E. coli O157:H7 in rumen fluid was inhibited by the autochthonous microflora. Growth was also reduced when rumen fluid came from sheep fed a mixed diet composed of 50% wheat and 50% hay, as opposed to a 100% hay diet. In fecal suspensions, E. coli O157:H7 growth was not suppressed by the autochthonous flora. However, a probiotic strain of Lactobacillus acidophilus inhibited E. coli O157:H7 growth in fecal suspensions. The inhibitory effect was dose dependent. These lactic acid bacteria could be a relevant tool for controlling O157:H7 development in the terminal part of the ruminant GIT, which has been shown to be the main site of colonization by these pathogenic bacteria.

Animals↗