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Topic:Animal Studies
Animal studies involving horses encompass a range of research focused on understanding equine biology, behavior, and health. These studies often investigate various aspects of horse physiology, genetics, nutrition, and disease pathology. Researchers utilize animal studies to explore the effects of different treatments, management practices, and environmental factors on horse welfare and performance. The findings from such studies contribute to the development of improved care strategies and health interventions. This page gathers peer-reviewed research studies and scholarly articles that explore the methodologies, findings, and implications of animal studies conducted on horses, providing insights into their application in advancing equine science.
[Physicochemical fat indices and the fatty acid composition of the lipids in mare’s milk and shubath (sour camel’s milk)]. Physicochemical properties of fat and fatty-acid composition of mare's milk and shubath (sour milk product obtained from camel's milk) depend on the season. During summer these products show a higher content of fat and increased level of polyunsaturated fatty acids, particularly in mare's milk lipids. It has been shown that in mare's milk lipids 90% is due to acids with a carbon chain of C14-18, while shubath lipids contain almost 96% of such acids.
Effects of enkephalins versus opiates on locomotor activity of the horse. The enkephalins are small, pentapeptide neurotransmitter molecules which have reportedly been used in racing horses. In our experiments, D-Ala2-Metenkephalinamide and leucine enkephalin were administered to horses intravenously (IV) and intracisternally (IC). Leucine enkephalin had little effect on locomotor activity by either route at doses of 0.01 mg/Kg or less. Methionine enkephalinamide, an enzyme resistant enkephalin analog, had no significant effect when given IV (0.002 and 0.008 mg/kg). Other experiments involving intracisternal dosing with this long acting form at higher levels (0.005-...
Serum and intracellular retinol in the equine. 1. Serum and intracellular distribution of retinol was determined in equines maintained on four levels of vitamin A intake. 2. The form of retinol transported in serum was determined by gel filtration and chromatography to be a complex of retinol bound to a protein of molecular weight (MW) of approximately 20000, which was in turn complexed probably with prealbumin to yield a complex with a MW of 75000 to 80000. 3. Increasing dietary vitamin A levels enhanced the concentration of lipoprotein-bound retinyl esters in the plasma. 4. Vitamin A in the liver cytosol was found predominantly as retiny...
Milk production of quarter horse mares during 150 days of lactation. Milk production was measured in fourteen Quarter Horse mares at seven stages of a 150-d lactation period. Mares were divided into two groups of seven and fed diets containing either soybean meal or soybean meal and urea as nitrogen supplements. Rations were isocaloric, contained approximately 12.5% crude protein and were fortified with vitamins and minerals. Daily milk yield was estimated by the weigh-suckle-weigh method and milk composition was determined from samples taken by hand milking. Average daily milk yield ranged from 11.8 kg in early lactation to 9.8 kg in late lactation. Difference...
Effect of stress on steroid hormone levels in racehorses. Cortisol and testosterone were measured by radioimmunoassay in plasma samples from race horses. None of 6 stressed male horses had low cortisol levels but testosterone levels (0.81 +/- 0.15 nmol/l) were significantly lower than in healthy horses (1.86 +/- 0.31 nmol/l). The conclusion was made that adrenocortical insufficiency is not a common association of stress in race horses. The reduction in testosterone levels is probably a nonspecific response similar to that seen in other species.
Capsular serotypes of Rhodococcus equi. One hundred strains of Rhodococcus equi from various animal species and sources in Australia were examined for capsular serotype. Eighty-four of the strains fell into the existing 7 serotypes, and just under half of the strains belonged to serotype 1. Isolates from the intestines and faeces of horses, cattle, pigs and other species, and from soil, were found to belong to the same serotypes as those recovered from the lungs of foals with R. equi pneumonia. There was no clear relationships between capsular serotype and source of origin of the isolates.
Teratological effects of western equine encephalitis virus on the fetal nervous system of Macaca mulatta. Fetal rhesus monkeys were inoculated intracerebrally with an attenuated strain of western equine encephalitis virus. All animals developed microcephaly. Twelve of sixteen monkeys developed ex vacuo hydrocephalus. All virus inoculated fetuses developed WEE virus antibody. Virus could not be recovered at the time of delivery. Monkeys with the highest WEE antibody titers showed the greatest degree of hydrocephalus.
Antibodies to the zona pellucida in mares. Cross-reactivity tests indicated that the equine zona pellucida shares common antigen(s) with porcine zona. Porcine oocytes were therefore used to test for the presence of zona antibodies in the sera of horses. Serum samples were collected from 65 mares infertile for unexplained causes: 7 mares were strongly positive for antibodies reactive to porcine zona pellucida as determined by an indirect immunofluorescence method. Of these 7 mares, aged 8-23 years, 2 were nulliparous and 5 were multiparous. Zona-covered horse oocytes were treated with sera from 4 mares previously identified as zona posi...
Tendon fibromas in 2 horses. FIBROMAS arise from connective tissue and occur in all domestic animals (Smith, Jones and Hunt 1972; Stannard and Pulley 1978). They are most frequently noted in the dermis or subcutis, but may be present wherever connective tissue occurs. In the dermis and subcutis of the horse fibromas are grossly similar to sarcoids and may be difficult to differentiate (Baker and Leyland 1975). Fibromas have been described as tumours of the tendon sheath or tendon proper in man (Flynn 1975), but have not been described in this location in the horse.
Calcium metabolism in glucocorticoid-treated pony foals. Pony foals were injected intramuscularly with 0, 0.5, or 5.0 mg dexamethasone per 100 kg body weight daily for up to 11 months. True absorption of dietary calcium was inhibited by treatment at 18 days (57% versus 14% of intake; P less than .01) and 10 months (72% versus 55% versus 43%: P less than .01), but not at 2 or 7 months, and was independent of age and treatment related decreases in intestinal calcium binding protein activities. Uninary excretion of calcium was increased by treatment through 7 months but decreased at 10 months. Treatment for 18 days resulted in total calcium excretions ...
Glucocorticoid suppression of oestrus, follicles, LH and ovulation in the mare. Dexamethasone, a synthetic glucocorticoid, was administered (30 mg/day) from Day 10 after ovulation to assess the involvement of the adrenal glands in the ovulatory cycle. Only 1 of 8 mares treated in this way exhibited behavioural oestrus, compared to 7 of 8 control mares. Mean maximum LH concentration and follicle size were significantly reduced. Ovulation occurred in 1 and possibly in 2 other treated mares, compared to all 8 control mares. The results demonstrated that dexamethasone can interfere with ovulation and associated events in the mare, but the mechanism of action is uncertain.
Characteristics and fertility of stallion semen. A study of stallion fertility was conducted on commercial studs in eastern Australia over 4 breeding seasons (1974/75-1977/78). Data from 47 stallions (66 stallion seasons) aged 2-26 years and representing 7 breeds and 1664 mares were used to relate seminal characteristics to fertility. Percentage pregnancies per service was the most sensitive measure of fertility with stallions on commercial studs. Breed and age of stallion, breeding season and the referral status of the stallion ('suspect' or 'normal') had significant (P less than 0.01) effects on fertility. The semen characteristics that we...
Time relationship between the respiratory cycle and limb cycle in the horse. Techniques developed for the detection and simultaneous recording of certain events in the respiratory and limb cycles are presented. The respiratory cycle and limb cycle were found to be in-phase only at the canter and gallop. The significance of any time relationship between events in respiration and in locomotion is discussed.
Chemical composition of the spinal cord in the normal developing fetus and in the premature foal. The lipid content of spinal cord, expressed as a percentage of adult values, was considerably higher for newborn foals than for several other species and traces of esterified cholesterol (type A) were only rarely present in horse fetal cord (from 270 days gestational age onwards). This suggested that, at birth, the spinal cord is neurochemically more 'mature' in the horse than in cattle, sheep and pigs. Data for premature foals revealed no lipid abnormality suggestive of myelin immaturity or degeneration.
Social organization of feral horses. The basic social unit in feral horses is the family group consisting of one stallion, one to a few unrelated mares and their foals. Surplus stallions associate in bachelor groups. Stallions are instrumental in bringing mares together in a unit which then persists even without a stallion. The similarity of social organization in populations living in a variety of different habitats indicates that feral horses have reverted to the habits of their wild ancestors, and that domestication has had no influence on this basic behavioural feature.
Fertility of frozen equine semen. Semen of 16 stallions collected by the fractionated method and frozen in liquid nitrogen was used to inseminate 175 mares of different ages and in various reproductive conditions. Pregnancy was recorded in 91 mares of which 72 delivered a foal. Pregnancy followed by resorption occurred in another 10 mares and 9 aborted. The best results were obtained in the young primiparous and in older mares inseminated in the oestrous cycle that followed the post-partum oestrus. Overall, 64% of mares became pregnant and 56% gave birth to a living foal. The highest occurrence of fetal death and resorption we...
Factors affecting testis weight in normal and cryptorchid horses. Testes were collected from normal and cryptorchid horses of a variety of breeds and ages and weighed after dissection from the epididymis. Scrotal testes grow little until the second winter of life and little thereafter, although a nearly mature body weight is reached by the end of the first winter. Scrotal testes in unilateral cryptorchids tend to be larger than those of normal stallions, sometimes exceedingly so, although occasional small scrotal testes are recorded. Inguinal testes show some tendency to grow during the second winter but the data are difficult to analyse beyond that age beca...
The optimum pH of renal adenosine triphosphatase in rats: influence of vanadate, noradrenaline and potassium. In the presence of vanadate, the optimum pH of renal (Na+, K+)-ATPase in rats is reduced and lies in the range of intracellular pH. This explains the difference in optimum pH observed with ATP extracted from equine muscle. Removal of vanadate from such ATP (with noradrenaline) raises the optimum to the accepted range obtained with synthetic ATP. Changes in the sensitivity of the enzyme to potassium concentration contribute to the alterations in optimum pH. The optimum pH of Mg-ATPase is unaffected by vanadate. Since vanadate may be an intracellular regulator of (Na+, K+)-ATPase changes of opti...
