Omneity® Pellets
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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.
Episodic LH secretion patterns in the mare during the oestrous cycle. Jugular blood samples were obtained from 8 mares at 5- and/or 20-min intervals for 2 to 5 days during various phases of the oestrous cycle for plasma LH determination. An episodic release pattern was observed in 1 of 3 mares sampled during the ovulatory period. One mare had one secretory burst and the other mare had several periods of fluctuating plasma LH concentration. During dioestrus, episodic secretions were observed in 2 mares sampled 11 to 13 days before and, in 1 mare, 9 days after ovulation. During the 2 to 5-day period before ovulation, episodic secretion was not observed (3 mares) b...
The binding of FSH, LH and PMSG to equine gonadal tissues. Gonadotrophin-receptor binding studies involving the use of 125I-labelled highly purified FSH and LH have shown that equine gonadal tissues possess similar numbers of specific FSH and LH receptors per cell as the gonadal tissues of other mammals. However, while rat, cow and pig gonadal tissues were shown to bind as much 125I-labelled PMSG as 125I-labelled LH on a molar basis, the equivalent equine tissues bound only less than or equal to 4% as much of the labelled PMSG as LH. Competitive binding studies involving the use of radioreceptor assay techniques have further demonstrated that the smal...
Localization of gonadotrophin-releasing hormone (GnRH) in the hypothalamus of ovariectomized pony mares by season. Fifteen Pony mares, ovariectomized during the previous summer, were randomly assigned to three seasonal treatment groups, winter, spring and summer (N = 5). At the designated season, the animals were killed and hypothalamic areas were collected and assayed by radioimmunoassay for gonadotrophin-releasing hormone (GnRH) activity. The hypothalamic areas were sectioned into 54 5-mm cubes to determine the sites of GnRH storage. Maximum immunoreactive GnRH activity was located in an oblique pattern extending from the arcuate nucleus-median eminence area to the anterior hypothalamic area dorsally and...
An enzyme immunoassay (EIA) for progesterone in horse plasma. A simple enzyme immunoassay (EIA) for the measurement of progesterone is described. Antibody against 11-OH-hemisuccinate-BSA is bound to polystyrene tubes. 11-OH-hemisuccinyl-beta-D-galactosidase is used as enzyme-coupled antigen and methylumbelliferyl-beta-D-galactoside as substrate. Concentrations down to 0.156 ng/ml plasm or amounts of 93 pg/tube are detectable. Probit analysis gave a linear relationship between log concentration and percentage of binding. A comparison of EIA and radioimmunoassay gave a correlation coefficient of 0.81. The assay is sufficiently sensitive to estimate progest...
Prostaglandins in maternal and fetal plasma and in allantoic fluid during the second half of gestation in the mare. The concentrations of the primary prostaglandins (PG) F-2alpha and E-2 and the metabolite 13,14-dihydro-15-oxo-prostaglandin (PGFM) in maternal and fetal plasma and in allantoic fluid were measured in chronically catheterized mares and fetuses. A gradual rise in all 3 PGs occurred with increasing gestational age. PGE-2 and PGF-2 alpha levels were highest in the allantoic fluid and lowest in the maternal plasma, whereas PGFM concentrations were greatest in maternal plasma. Significant venous-arterial plasma differences in PGFM concentration were detected across the uterine circulation between 1...
Changes in mammary development and composition of secretion during late pregnancy in the mare. Small samples of mammary secretion were taken for analysis from Thoroughbred mares during the last 3 weeks of pregnancy up to the time of foaling. The concentrations of sodium and chloride decreased while those of lactose, potassium, citrate, phosphate, calcium, magnesium and protein increased. The time-course of these changes showed marked variation between animals. The concentration of whey proteins began to increase about 10 days before parturition. The appearance of the secretion and the size of the mammary glands increased in the last few days of pregnancy. It is suggested that the concen...
DNases in milk and blood sera from different species. DNases were demonstrated in samples of colostrum and blood serum from man and various domestic animals. The measurable DNase activity recorded was highest in samples from cat and dog and lowest in samples from goat, horse, pig and sheep. In contrast to DNases produced by certain bacteria, these enzymes were thermo-labile and the activity was maximal in the area pH 5.0–5.5. A modification of an agar medium originally described for the demonstration of bacterial DNases was found to be suitable for assays of DNases from colostrum, milk and serum. DNaser ble påvist i prøver fra kolostrum og bl...
[Myocardial changes following experimental protein sensitization]. Guinea pigs were sensitized by three subcutaneous injections of 0.1 ml native horse serum at 2-day intervals, 21 days after the third injection the animals developed marked sensitization to this antigen which was manifested by anaphylactic reaction to the subcutaneous challenge with this antigen. At this time, the myocardium of the sensitized animals showed signs of extra- and intracellular oedema, a sharp increase in the number of lysosomes, damage of their membranes, 2 1/2 months after sensitization the animals showed no anaphylactic reaction to the challenge dose of the antigen. There were ...
Isoelectric focusing of some enzymes from Echinococcus granulosus (horse and sheep strains) and E. multilocularis. Extracts of the horse and sheep strains of Echinococcus granulosus and E. multilocularis were compared on the basis of their isoenzyme patterns for 10 enzymes by means of isoelectric focusing in polyacrylamide gels. The enzymes examined were: acid phosphatase, lactate dehydrogenase, malate dehydrogenase, malic enzyme, phosphoglucoseisomerase, isocitrate dehydrogenase, adenylate kinase, aldolase and alpha-glycerophosphate dehydrogenase. Interspecific and intraspecific differences are apparent in the isoenzyme profiles of all the enzymes except adenylate kinase; the pattern and activity of adeny...
Preparation and some properties of a dimeric form (S-S) of horse muscle acylphosphatase. The use of sodium selenite as a catalyst in the presence of oxygen was a suitable technique to obtain in good yield an interchain S-S dimeric form of horse muscle acylphosphatase. The dimer so obtained possesses kinetic properties very similar to those of the native enzyme. On the other hand the dimer has shown a generally lower stability in respect of the thermal inactivation, particularly in the acidic environment, to the lyophilization and to the proteolytic attack. As regards the 8 M urea inactivation, the dimer is not able to completely regain its activity by dilution, showing a behaviour...
Differences in the histochemical properties of skeletal muscles of different breeds of horses and dogs. Histochemical profiles of individual muscle fibres were established using myosin adenosine triphosphatase (myosin ATPase), succinate dehydrogenase (SDHase), and glycogen phosphorylase (GPase) reactions in three muscles (semitendinosus, diaphragm, and pectoralis transversus) of the horse and dog. The major histochemical difference between fibres lies in their myosin ATPase activity; fibres can be subdivided into those with a high and those with a low activity. In horse muscle, all fibres have a high activity of GPase. In the diaphragm and pectoralis transversus, all fibres have a high SDHase ac...
Formation of steroids by the pregnant mare. VI. Metabolism of [14C]farnesyl pyrophosphate and [3H]dehydroepiandrosterone injected into the fetus. A mixture of [4,8,12-14C]farnesyl pyrophosphate and [3H]dehydroepiandrosterone was injected into a horse fetus im during laparotomy, after which maternal urine was collected for 6 days. Steroid conjugates in the urine were extracted with Amberlite XAD-2 resin, hydrolyzed, and separated into phenolic and neutral fractions. Estrone, 17 alpha-estradiol, equilin [3-hydroxy-1,3,5(10),7-estratetraen-17-one], and 17 alpha-dihydroequilin [1,3,4(10),7-estratetraene-3,17 alpha-diol] were isolated from the phenolic fraction and their radiochemical purities were established. Only estrone and 17 alpha-estr...
The measurement of oestrone, equilin and dehydroepiandrosterone in the peripheral plasma of pregnant pony mares by radioimmunoassay. Oestrone, equilin and dehydroepiandrosterone were measured by radioimmunoassay in peripheral plasma from five pony mares; samples were taken from day 60 of pregnancy at approximately weekly intervals through to parturition. Of the three steroids measured, dehydroepiandrosterone showed the most consistent pattern of secretion. DHA concentrations remained low until day 105, increased rapidly from day 120 and attained maximum values between days 168–210; levels declined to day 300, but there was considerable variation between mares in DHA patterns prior to parturition. There was great variation...
Alkaline isomerization of horse and yeast cytochromes C. Spectrophotometric and circular dichroism studies. Spectrophotometric studies of the alkaline isomerization of horse heart and yeast cytochrome c show that the haemoproteins from Saccharomyces cerevisiae differ significantly from the mammalian cytochrome c. Apparent pKa values of 8.41, 8.40 and 8.73 for isol-1-(the methylated and unmethylated forms) and iso-2-cytochrome c respectively, from baker's yeast were determined and compared with the value of 9.40 found for horse heart cytochrome c. The transitions, measured by observing the decrease of the absorbance at 695 nm as the pH increases, have been found to strictly parallel the decrease in a...
Radioimmunoassay of oxfendazole in bovine, equine, or canine plasma or serum. A simple radioimmunoassay was developed for the determination of oxfendazole in plasma. Oxfendazole N-1(3)-valerate was coupled to polylysine via a carbodiimide reaction, and antiserum was developed in rabbits after inoculation with oxfendazole--polylysine conjugate. The assay was developed so that oxfendazole could be measured directly in a 0.1-ml aliquot of diluted or undiluted plasma. With the developed procedure, 200 pg of oxfendazole/ml of plasma can be determined quantitatively. Cross-reactivity was determined for closely related compounds and metabolites. The method was used to determin...
Observations on thyroid hormones in the blood of thoroughbreds. During an investigation of a group of clinically well thoroughbreds housed in the same stable, it was noted that seven of the 14 had no detectable thyroxine in the plasma (less than 5 nmol/litre). An investigation of thoroughbreds in this stable over a five month period suggested that the thyroids were functioning normally and that the thyroxine was excreted in the urine. Thyroxine binding studies on the blood of these horses suggested that the major part of the circulating thyroxine was bound to albumin. The thyroxine had been displaced resulting in an apparent absence of plasma thyroxine sin...
Uterine luminal prostaglandin F in cycling mares. Prostaglandin F was measured by radioimmunoassay in uterine flushings of cycling mares on days 4, 8, 12, 14, 16, 18 and 20 post-ovulation. Prostaglandin F was significantly (P less than .05) affected by day of the estrous cycle and reached maximal levels on day 14. Least squares means for days 4, 8, 12, 14, 16, 18 and 20 were: .66, .81, 4.77, 14.31, 5.48, 3.68 and 2.97 ng/ml, respectively.
Inhibition of calcium absorption in ponies fed diets containing oxalic acid. The effects of dietary oxalic acid on absorption, excretion, and retention of calcium was determined in Shetland ponies in 2 experiments. In each experiment, the results of feeding a control diet consisting of oats, molasses, and a complete pelleted horse ration were compared with those of feeding the control diet plus 1% oxalic acid. The diets contained 0.6% calcium in the 1st experiment and 0.45% calcium in the 2nd experiment. Oxalic acid increased the fecal excretion of calcium and decreased calcium absorption. The endogenous fecal excretion of calcium determined in the 1st experiment, usin...
Physiological implications of microbial digestion in the large intestine of mammals: relation to dietary factors. The rate of digesta marker passage through the large intestine of the dog, pig, and pony correlated with the relative length and degree of sacculation of the colon. Volatile fatty acids (VFA), the end products of microbial digestion of all forms of carbohydrate, were the major anions present in large intestinal contents of all three species. Total VFA concentration was little affected by the feeding of high-versus low-fiber diets. VFA were rapidly transported across colonic mucosa of all three species. Results of comparative studies indicate that production and absorption of VFA are important ...
Increased plasma bromide concentration in the horse after halothane anesthesia. A long-lasting increase of the plasma bromide concentration was found in 25 horses after clinical halothane anesthesia. The plasma bromide concentration was significantly (P less than 0.005) increased at the end of anesthesia. In 18 horses, peak values were reached between 48 and 72 hours after anesthesia. Eighteen days after horses had been anesthetized, the plasma bromide concentration remained significantly (P less than 0.005) increased. Significant correlation was not found between the total dose of halothane and the plasma bromide concentration. In 1 horse reanesthetized with halothane 4 ...
Reference values for clinical chemistry using the Coulter Chemistry System. Reference (normal) ranges were established for clinical chemistry results obtained from the Coulter Chemistry instrument on specimens from dogs, cats, horses, and cattle. These results, in general, are very similar to those reported in the current veterinary literature. The specimens obtained from horses and cows were subdivided according to age and lactation status, respectively. Significant differences were noted between the subgroups in the results of certain tests.
Effects of furosemide on plasma volume and extracellular fluid volume in horses. The effects of IV administered furosemide upon plasma volume (PV) and extracellular fluid volume were determined in horses at rest and after exercise. Serum sodium, potassium, chloride, and osmolality determinations were made. Furosemide caused a significant (P less than 0.05) decrease in PV and serum potassium concentrations in resting horses only. Furosemide's effects upon PV and electrolytes were evident longer than its hemodynamic effects.
Glucose transport by horse kidney brush borders. I.–Transport properties of brush border membrane closed vesicles. Brush border membranes isolated from horse kidney cortex as closed right-side out vesicles show selective permeability when analyzed on sucrose and dextran gradients. These vesicles can actively accumulate D-glucose. The preservation of the glucose transport system is demonstrated by the following features: (a) the uptake and release rates of D-glucose are higher in the presence of a sodium gradient, showing that D-glucose transport is a sodium-dependent process; (b) this transport, specific for the D-isomer, is inhibited by phlorizin; (c) the D-glucose transport system is saturable; (d) no in...
Fourier transform infrared spectroscopic study of molecular interactions in hemoglobin. Infrared absorption spectra of the alpha-104 (G11) cysteine SH group have been observed for aqueous solutions of hemoglobin derivatives from humans, pigs, and horses. The center frequencies ((nu)SH) show ligand sensitive patterns that are similar for the three species, with (nu)SH (HbCO) <(nu)SH (HbO(2) ~ HbCN) < (nu)SH (Hb(+)) <<(nu)SH (deoxyHb) for human and pig hemoglobins. The alpha-104 SH group is most strongly H-bonded (smallest (nu)SH), has the greatest range of (nu)SH (Hb ? HbCO) in human hemoglobin, and is least strongly H-bonded and has the smallest range of (nu)SH (Hb ? ...
Acid-base status of equine blood during storage. The changes in pH, pCO2, pO2, BE, SBC, and lactic during storage of equine venous and arterial blood in 24 hours at different temperatures were measured (tables I, II), and illustrated (fig, 1, 2, 3). Correction tables (tables VI, VII) for determination of the initial acid-base data are constructed based on regression equations (tables IV, V) of the in vitro changes of the blood. The changes in the acid-base values of equine blood differ from that of bovine and canine blood (table III).
