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Topic:Biochemistry
The study of biochemistry in horses encompasses the chemical processes and substances that occur within equine organisms. This field investigates the molecular interactions and pathways that are fundamental to horse physiology, including metabolism, enzyme activity, and genetic expression. Key areas of interest include the examination of metabolic disorders, nutrient absorption, and the biochemical basis of muscle function and energy production. Researchers utilize biochemical analysis to understand health and disease mechanisms in horses, contributing to the development of diagnostic tools and therapeutic strategies. This page gathers peer-reviewed studies and scholarly articles that explore various biochemical processes and their implications for equine health and performance.
Responses to submaximal treadmill exercise and training in the horse: changes in haematology, arterial blood gas and acid base measurements, plasma biochemical values and heart rate. Four standardbred horses with subcutaneously relocated carotid arteries were given a seven week training programme of treadmill exercise at a gradient of 19 per cent in order to assess if there were any effects of exercise and training on haematology, arterial blood gas and acid base measurements, plasma biochemistry and heart rate. The exercise consisted of one minute walking at 110 metres/minute followed by five minutes trotting at 200 metres/minute, twice daily in the first week. The period of trotting exercise was increased by one minute per week so that by the seventh week the horses were...
A distinct environment for iron (III) in the complex with horse spleen apoferritin observed by x-ray absorption spectroscopy. Cell-specific variations in apoferritin structure correlate with variations in iron metabolism that suggest functional specificity of the protein shell. Using EPR spectroscopy, we previously showed that vanadyl binds to specific sites on apoferritin, and that VO2+ binding is reduced by Fe(II) and Fe(III) (the natural substrates) and by metals known to influence iron storage (Chasteen, N. D., and Theil, E. C. (1982) J. Biol. Chem. 257, 7672-7677). Such observations suggest that the metal-binding site is important to apoferritin function and may define a location where the influence of cell-spec...
Increased susceptibility of fibroblasts from horses with severe combined immunodeficiency to growth inhibition by 2′-deoxyadenosine. The effect of adenosine, deoxyadenosine, guanosine, and deoxyguanosine on the growth rate of fibroblasts derived from normal horses, horses heterozygous for the severe combined immunodeficiency (SCID) trait (heterozygotes), and horses with SCID was studied. All four purines were found to inhibit growth in a dose-dependent manner, but only adenosine and deoxyadenosine were inhibitory at concentrations of less than 100 microM. No statistical difference in sensitivity to adenosine was detected between normal and SCID fibroblasts. Fibroblasts from SCID horses were, however, more sensitive to the g...
Studies on prolactin: conformational comparison of human, equine, and porcine pituitary prolactins. The conformations of human, equine, and porcine pituitary prolactins, as evidenced by various optical properties, have been compared. The alpha-helix contents of all three proteins are essentially identical to each other (60 +/- 5%), as well as to prolactins isolated from other mammalian species. Direct absorption (zero and second-order), difference absorption, fluorescence emission, and circular dichroism spectra suggest that the majority of tyrosine and tryptophan side chains in these three proteins exist in very similar microenvironments within the folded forms of the hormones. Thus, the ge...
[Antiluteolytic activity of embryos in various animal species]. In mare, sheep and bitch the action of PGF2 alpha have been studied in the early pregnancy. Prostin F2 alpha (Upjohn) and Gabbrostim (Vetem ) are commercial names of PGF2 alpha used at doses which are luteolytic in the non pregnant female. Seric progesterone showed a temporaneous decrease but after four or five days the initial values were restored and none of the experimental females aborted. In the opinion of authors, embryo per se and/or with its adnexa might have interacted blocking the mechanism of luteolysis induced by the administration of PGF2 alpha.
Changes in plasma cortisol concentrations during the ovulatory cycle of the mare. Daily blood samples from four mares were assayed for cortisol through a total of eight ovulatory cycles. Mean cortisol concentrations on days -14, -13, -10, -9 and -8 before ovulation (dioestrus) were greater than on days -5 to -1 (oestrus). The highest mean (+/- S.E.M) value of cortisol occurred on day -10 (260 +/-28 nmol/l) and the lowest on day -2 (142 +/- 14 nmol/l). A single episode on a day in late dioestrus characterized the maximum cortisol value per cycle for five of eight cycles. Extraction of plasma samples with petroleum ether or chromatography before assay, to eliminate interferen...
Phloroglucinol microassay for plasma xylose in dogs and horses. The phloroglucinol microassay technique for measuring plasma concentrations of xylose was compared with the more tedious orcinolferric chloride technique. Sequential blood samples were collected from 5 dogs and 6 horses every 30 minutes after oral administration of 0.5 g of D-xylose/kg of body weight. Comparison of the results by regression analysis shows a highly significant (P less than 0.01) positive linear correlation for both dogs (r = 0.95) and horses (r = 0.77). These results indicate that xylose in canine and equine plasma can be accurately measured by the phloroglucinol technique.
Horse red blood cells frozen with 20% (w/v) glycerol and stored at -150 C for five years. When equine RBC were frozen with 20% (w/v) glycerol and stored at -150 C for as long as 5 years, there were no adverse effects on freeze-thaw or freeze-thaw-wash recovery or oxygen transport function. The manner in which the glycerol was added to, and removed from, the equine RBC was shown to be an important consideration in ensuring optimal freeze-thaw-wash recovery values.
Effects of testosterone, dihydrotestosterone and estradiol on gonadotropin release after gonadotropin releasing hormone administration in cyclic mares. Sixteen intact cyclic mares were treated on the fourth day of estrus and then every other day for a total of six injections with 1) testosterone propionate, 2) dihydrotestosterone (DHT) benzoate, 3) estradiol (E2) benzoate or 4) safflower oil. Mares were given gonadotropin releasing hormone (GnRH) on Day 3 of estrus (pretreatment) and again 24 h after the last steroid or oil injection. Treatment with testosterone propionate resulted in a greater (P less than 0.05) follicle-stimulating hormone (FSH) response to the second injection of GnRH compared with all other treatments. Treatment with DHT ...
The use of heterologous radioimmunoassays for the measurement of follicle-stimulating hormone and luteinizing hormone concentrations in horse and donkey serum. Heterologous double-antibody radioimmunoassay were developed for the measurement of FSH and LH concentrations in the serum of both horses and donkeys. The FSH assay employed a rabbit anti-ovine FSH serum which showed a complete lack of cross-reaction with equine chorionic gonadotrophin (eCG) and negligible cross-reaction with equine LH. The LH assay utilized an antiserum raised against highly purified eCG. This similarly showed negligible cross-reaction with equine FSH but its high cross-reactivity with eCG prevented the measurement of equine LH concentrations in serum when eCG was also presen...
Proton nuclear magnetic resonance studies of histidines in horse carbonic anhydrase I. The 250 MHz 1H-NMR spectrum of horse carbonic anhydrase I (or B) (carbonate hydro-lyase, EC 4.2.1.1) was measured as a function of pH under various conditions. Eight resonances corresponding to histidine C-2 protons and four resonances corresponding to histidine C-4 protons were identified and assigned to individual histidine residues in the enzyme molecule. Substantial similarities between horse and human carbonic anhydrases I were demonstrated. While the human enzyme has three titratable histidine residues in its active site, the horse enzyme has only two, His-67 in the human enzyme being re...
Affinity chromatographic purification of horse muscle acylphosphatase: evidence of the existence of multiple molecular forms. Acylphosphatase was purified from horse muscle by a new procedure involving an affinity chromatography step and subsequent ion-exchange chromatography. This procedure was considerably milder than the preceding one, gave an overall yield of about 60% of activity and permitted isolation of three molecular forms with acylphosphatase activity. All these enzymatic forms are tightly bound to Sepharose 4B-linked anti-horse muscle acylphosphatase antibodies. Two of these forms (Ho1 and Ho3) are present in larger amounts: Ho1 corresponds to the enzyme purified according to the older procedure; this enz...
Automated serum chemical analysis in the foal. Blood was collected from healthy Quarter Horse and Appaloosa foals at birth and at intervals until 18 weeks of age and then was processed in an automated system for serum chemical analysis, grouping the results by age. The test values were markedly different from those normally expected in adult horses. The greatest differences were in alkaline phosphatase, lactate dehydrogenase, glucose, and total bilirubin measurements. It was concluded that serum biochemical test results be compared with age-specific normal values before diagnoses are made in cases of illness.
Glutathione peroxidase activity in the blood of healthy horses given different selenium supplementation. Glutathione peroxidase (GSH-px) activity in the blood is correlated to the amount of selenium which was given to the horse. Currently recommended doses of selenium seem to be sufficient in order to prevent selenium deficiency. The blood GSH-px in foals reflects the amount of selenium given to the mare during pregnancy.
Identification of 3 beta-hydroxy-5,7-pregnadien-20-one and 3 beta-hydroxy-5,7-androstadien-17-one as endogenous steroids in the fetal horse gonad. The 5,7-dienes, 3 beta-hydroxy-5,7-pregnadien-20-one and 3 beta-hydroxy-5,7-androstadien-17-one were extracted from fetal horse gonads and purified by solvent partition, thin-layer chromatography and high performance liquid chromatography. The isolated steroids were identified by comparison with the synthetic steroids using ultraviolet and mass spectroscopy and by gas chromatography-mass spectroscopy. The identification of these compounds as endogenous steroids, together with the data on their biosynthesis reported previously, support the proposal that in the fetal horse gonad there is a 5,7-d...
Comparison of pyrimidine 5’nucleotidase activity in erythrocytes of sheep, dogs, cats, horses, calves, and Mongolian gerbils. Pyrimidine 5'nucleotidase (P5N) activities of erythrocytes for Mongolian gerbils, cats, dogs, sheep, horses, and calves were measured, using a radiometric technique with [14C]cytidine monophosphate as the substrate. Erythrocytes of gerbils had the highest activity [1,177.1 +/- 133.6 mU/g of hemoglobin (Hb)]. Feline erythrocytes had 327.4 +/- 204.4 mU/g of Hb. Canine erythrocytes had 148.0 +/- 19.8 mU/g of Hb. Ovine erythrocytes (44.3 +/- 20.9 mU/g of Hb), equine erythrocytes (30.0 +/- 15.9 mU/g of Hb), and bovine erythrocytes (14.1 +/- 6.9) had relatively low P5N activity. The P5N activity was...
[Various aspects of lactate production and disappearance in trotters during exertion]. Venous lactate concentrations were determined in standard-bred trotters following exercise of varying intensity to obtain a useful parameter in determining the working capacity of horses. After standard exercise, well-trained horses produced less lactate than did inadequately trained horses. During the post-exercise resting period, lactate disappeared faster from the blood in well-trained horses and young lightly trained horses than it did in poorly trained horses. Steady-state training resulted in lower lactate levels than those recorded after racing, whereas interval training resulted in the...
High-performance liquid affinity chromatography on silica-bound alcohol dehydrogenase. Horse liver alcohol dehydrogenase was immobilized on glycerylpropyl-silica (10 micron, 1000-A pores) activated with 2,2,2-trifluoroethanesulfonyl chloride (tresyl chloride). The coupling and activity yield was almost 100%. The coenzyme-binding sites were equivalent and virtually unaffected by the immobilization process, as judged from Scatchard plots and active-site titrations. The silica-bound enzyme, packed in steel columns, was integrated with HPLC equipment and then successfully used for chromatography of adenine nucleosides, adenine nucleotides, and triazine dyes. Dissociation constants w...
Release of 3H2O from 1 beta,2 beta[3H]androstenedione by equine granulosa cells. Granulosa cells were harvested from mares at various stages of the oestrous cycle and incubated in Krebs-Ringer bicarbonate buffer with 1 beta,2 beta[3H]androstenedione as substrate. The release of 3H2O expressed as CPM/h/mg protein varied from 44000 to 768000 in follicles from 7 mares. The release of 3H2O was not significantly altered by luteinizing hormone, follicle stimulating hormone or pregnant mare's serum gonadotrophin. There was a significant negative correlation between the release of 3H2O and the concentration of progesterone in the follicular fluid. Based on the assumption that the ...
Modulation of equine platelet function by diethylcarbamazine (DEC). Equine platelets, when treated with the anthelmintic drug diethylcarbamazine (DEC), gave a dose-dependent release of radiolabeled serotonin without concomitant aggregation. At levels of the drug that gave only minimal release of radiolabel, marked dose-dependent inhibition of platelet aggregation to three of four platelet agonists tested--adenosine diphosphate (ADP), collagen, and arachidonic acid--was observed. With ADP, inhibition was observed to be reversed by removal of DEC prior to agonist challenge. However, with collagen, inhibition was only partially reduced by prior removal of DEC; wh...
Enzymatic trimethylation of lysine-72 in cytochrome c. The present observations are the continuation of our earlier study on the physicochemical mechanism of protein-lysine methylation. In this paper the electrophoretic behaviour (pI values) of two chemically modified horse heart cytochromes c at lysine-72 with trifluoromethylphenylcarbamoyl (neutral group) or carboxydinitrophenyl (acidic group) is compared with the enzymatically methylated cytochrome c. The results indicate that although both chemically modified cytochromes c have lower pI values than the unmodified cytochrome c, the enzymatic methylation appears to be much more efficient in lowe...
Measurement of superoxide dismutase, diamine oxidase and caeruloplasmin oxidase in the blood of thoroughbreds. Methods were developed for the measurement of superoxide dismutase (SOD), diamine oxidase (DAO) and caeruloplasmin oxidase in the blood of thoroughbred horses. These enzymes were measured in 178 normal thoroughbreds stabled throughout the United Kingdom. The relationships between the activities of SOD, DAO and caeruloplasmin oxidase and the blood concentrations of their associated trace metals (copper, zinc and manganese) were studied in 52 of the thoroughbreds. Trace metals were measured by electrothermal atomic absorption spectrophotometry. No relationships were found between the activities ...
Sodium and potassium ion-dependent change in oligomerization of Na,K-ATPase in C12E8 detected by low-angle laser light scattering technique in combination with high performance porous silica-gel chromatography. Approximate molecular weights and the subunit structures of Na,K-ATPase from horse kidney were estimated by means of the combination of porous silica gel chromatography, laser light scattering (LS) and refractive index (RI) measurements in C12E8. When the enzymes were eluted with NaCl- or KCl-containing solution, 3 or 4 protein peaks, respectively were detected except that of low molecular weight range. These peaks were tentatively named Na-1, Na-2, Na-2', Na-3 (NaCl-containing eluents), K-1, K-2, K-3 (KCl-containing eluents), respectively. Na,K-ATPase and K-p-nitrophenylphosphatase activities...
Linkage of the equine serum esterase (Es) and mitochondrial glutamate oxaloacetate transaminase (GOTM) loci. A horse-mouse homology. Three previously described electrophoretic phenotypes of mitochondrial glutamate oxaloacetate transaminase (GOTM) in horse leukocytes are shown to be controlled by two codominant alleles at a single autosomal locus. The GOTM locus is linked to the serum esterase locus (Es), as no recombination between these loci was observed among 16 informative offspring in one sire family. The results assign GOTM to equine linkage group (LG) II. The hypothesis that a part of LG II (e-Es) shares homologies with mouse chromosome 8 is thus confirmed, as the murine homologue of GOTM is located within the cluster...
The in vitro effects of EDTA-tris, EDTA-tris-lysozyme, and antimicrobial agents on equine genital isolants of Pseudomonas aeruginosa. Five isolants of Pseudomonas aeruginosa collected from clinical cases of equine genital infection and one standard strain of P. aeruginosa were exposed to various concentrations of ethylene-diaminetetraacetic acid (EDTA) and tris (hydroxymethyl) aminomethane (tris buffer pH 8) and EDTA-tris lysozyme. Colony forming units of the isolants and minimal inhibitory concentrations for 11 antimicrobial agents were determined with each isolant before and after exposure to the EDTA solutions. Decreased cellular viability was found with all six isolants after exposure to the EDTA-tris solutions. Reversal...
