Arabian Stallions Research Articles

Serum testosterone in Arabian stallions during breeding and non-breeding seasons in Iran

The study was conducted to investigate the serum testosterone concentrations of Arabian stallions during breeding and non-breeding seasons under natural photoperiodic condition in west south of Iran (Khuzestan Province; latitude 48:40°N, longitude 31:20°E and altitude 22.5 m). The blood samples (10 ml) were collected from the jugular vein, and it stood at room temperature for 3 h and was centrifuged. The sera were kept at -20°C until assayed by radioimmunoassay. The results show that total serum testosterone levels (ng/ml) in Arabian stallions was higher in May to June (Summer Solstice; 1.08±0.078) than in November to December (Winter Solstice; 0.65±0.11) (p<0.05). We conclude that serum testosterone concentration during the non-breeding season is lower than that of the breeding season. The results confirm a seasonal rhythm in the reproductive cycle of Arabian stallions over the year in this specific region.

Vimentin expression in testes of Arabian stallions

Specific patterns of cytoskeletal filaments reflect a functional state of the cell. In testicular cells intermediate filaments (IFs) are of the vimentin type. Since it is known that Sertoli cells regulate the spermatogenic function in the male gonad, it became important to propose a system that could quantify the state of seminiferous tubular quality. To date, a Johnsen score system has never been used to equine testes. To demonstrate the expression pattern of vimentin in testes of mature Arabian stallions and correlate its distribution with grade of seminiferous tubule impairment as indicated by a Johnsen score. For histological examination by the Johnsen method, routine haematoxylin-eosin staining was used. Vimentin expression and its presence in testicular sections and testicular homogenates were detected by immunohistochemistry and western blot, respectively. Both analyses were performed qualitatively and quantitatively and further validated by ANOVA tests. Distinct morphology of seminiferous tubules was found in testes harvested from 3 stallions. Vimentin in IFs was immunolocalised to the cytoplasm of Sertoli, Leydig and peritubular-myoid cells. The intensity and pattern of the IFs staining was different in individual seminiferous tubules suggesting a correlation between vimentin expression and the severity of tubule degeneration. Qualitative results by immunohistochemistry and western blot were confirmed by further quantitative analyses. In equine testes, differential expression of vimentin was found to be correlated with the impairment of seminiferous tubules indicated by a decrease in Johnsen score. The Johnsen score system may be a useful method to facilitate the identification of tubular alterations in the stallion testes. Combined histological and immunohistochemical approach may provide a detailed phenotypic classification of stallions with decreased fertility.

Effect of vitamin-mineral premix on some relationships between serum parameters in breeding horses

Eight Arabian stallions were selected from clinically normal horses. After 10 day adaptation period the animals were divided into two equal groups: control and experimental. All horses were housed individually and allowed to walk on sandy paddock twice a day between meals. Both groups were fed the same diet which was composed of 6 kg hay and 4 kg barley. However, the experimental group was supplemented with 150 g of micronutrient premix. Premix was composed of 180 g of oats husk meal, 260 g dicalcium phosphate as carrier, 25 g lignosulphate, 20 g methionine, 20 g lysine, 200 g calcium, 40 g salt (NaCl), 30 g soy oil, 100 g yeast, 50 g mixture of vitamins, 75 g mixture of minerals and antioxidants per kg. The experiment was divided into adaptation and experimental period that lasted 10 and 30 days, respectively. The blood was drawn at the beginning of experimental period and thereafter in 10 days intervals. Serum samples were analysed for total serum protein, serum urea, serum lipids, serum glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT). The results showed highly significant differences between both groups in serum protein, serum lipids, serum GOT and GPT. Significant difference has been found between both groups in serum urea (P &lt; 0.1). These changes in serum parameters between groups could be due to the additive micronutrient premix fed to the experimental groups. The correlations between parameters: protein and urea was significant negative, between lipids and GOT highly significant negative, and between lipids and GPT non-significant.

Ultrasonographic measurements of accessory sex glands, ampullae, and urethra of normal stallions of various size types

For the purpose of establishing clinical reference values, this paper reports results of ultrasonographic examination and measurement of accessory sex glands, ampullae, and the pelvic urethra of 102 mature, healthy breeding stallions (2–29 years of age) of various size types (7 Miniature Horses, 27 small ponies, 53 light horses and 15 heavy horses). Examinations were done per rectum in mostly unsedated stallions using an Aloka 210 scanner with a 7.5 MHz linear veterinary transrectal transducer (Corometrics Medical Systems, Inc., North Wallingford, CT, USA). Most measures of accessory sex glands, ampullae and the urethra were larger in horses of larger sizes. Except for vesicular glands, the majority of the measures for all glands were smaller for Miniature Horses and ponies than for light horses and heavy horses ( P<0.05). For vesicular glands, measures for heavy horses were greater than for those of other groups ( P<0.05). Measures were similar for Miniature Horses and ponies, and for light horses and heavy horses. For all measures, differences between left and right paired glands were not different ( P>0.10). The lumen diameter of vesicular glands and ampullae as well as prostate lobe thickness showed the greatest asymmetry. Although there were too few representatives of various breeds for statistical comparison, among the light horse breeds Arabian stallions had the smallest mean values for the majority of the measures. Among stallions, echogenic characteristics of accessory sex glands, particularly vesicular glands, varied widely, possibly related to variation in recent sexual activity. For some stallions, echogenic character, particularly that of vesicular glands, varied remarkably from left to right gland within stallions. For ampullae, there was also wide variation in lumen contents between stallions. These data are generally consistent with previous reports with smaller numbers of stallions, as well as consistent with in vitro measures in previous studies. The results provide useful clinical guidelines for size measures of accessory sex glands in horses.

Calcium, magnesium, copper, and zinc in seminal plasma of fertile stallions, and their relationship with semen freezability

Seminal plasma contains several microelements like Zn, Fe, Se, and Cu that affect sperm motility and male fertility. Biochemical evaluation of seminal plasma trace elements is important for assessing fertility and diagnosing male infertility.The present study was designed to evaluate the effect of seminal fluid trace elements on sperm parameters and fertility in Arabian horses.Ninety-four ejaculates from 25 Arabian stallions (4–27 years old) were used to investigate the effect of seminal fluid trace elements on semen parameters and fertility. Data divided according to season, stallion age, and fertility of stallions. The concentrations of Zn, Fe, Se, Cu, Cr and Mo were determined using an atomic absorption spectrophotometer. Percentage stallion fertility estimated by mares that conceived on their first cycle. Data were analyzed by ANOVA using SPSS statistical software program (2013), version 22.0.There was a significant effect of season on semen volume, pH, Fe, Se, Cu, Cr, and Mo. Stallion age had a significant effect on pH, sperm motility, concentration, total motile sperm count, sperm abnormalities, Zn, and Fe. Sperm motility was higher (P < 0.05) and sperm abnormalities were lower (P < 0.05) in group IV (>70% fertility) than in group I (infertile) and group II (<50% fertility). Sperm abnormalities were low in group IV and high in groups I and II. Seminal plasma Zn and Cu levels were higher (P < 0.05) in groups III (50_70% fertility) and IV than in group I. Fe levels were lower (P < 0.05) in group IV than in groups I, II, and III. Seminal plasma Mo concentrations were higher (P < 0.05) in group III than in group I.High seminal plasma concentrations of Zn, Se, Cu, and Mo and low Fe concentrations are associated with improved stallions' semen parameters and fertility.

Influence of age and season on certain biochemical constituents of seminal plasma of Arabian horses

The study used 36 mature (4–25 years of age) and healthy Arabian horses reared at a government stud near Cairo. A total of 75 ejaculates was collected from these animals during a complete annual cycle and included 53 ejaculates from 30 stallions to estimate the influence of consecutive seasons and ages on seminal plasma concentrations of glycerylphosphorylcholine (GPC), ergothioneine (EGT), fructose, citric acid, total protein (PRT) and total carbohydrate. The respective overall mean (±SEM) values of these constituents were 75.91 ± 3.44 mg per 100 ml, 13.86 ± 0.79 mg per 100 ml, 7.85 ± 0.56 mg per 100 ml, 44.12 ± 1.83 mg per 100 ml, 644.92 ± 31.72 mg per 100 ml and 39.74 ± 1.57 mg per 100 ml seminal plasma. There were statistically significant age-related effects on seminal plasma concentrations of GPC, EGT and PRT, with seasonal effects on all six measured constituents. Modulation of the selected seminal plasma constituents by age and season must be considered when selecting Arabian stallions for fertility.

XY sex-reversal syndrome in the domestic horse.

The XY sex-reversal syndrome occurs when a phenotypic mare is born that has the karyotype of a stallion. The syndrome is manifested by both genotypic and phenotypic heterogeneity. The sex-reversed genetic condition occurs frequently within certain pedigrees where XY females have been found and can be readily detected by chromosome karyotyping. The phenotypic spectrum ranges from the feminine mare with a reproductive tract that is within normal limits to the greatly masculinized mare. Pedigree analysis suggests that there are two modes of inheritance: (1) an X-linked recessive or autosomal sex-limited dominant transmitted through the female and (2) an autosomal sex-limited dominant or a Y chromosomal mutation with variable expression transmitted through the male. The proportion of female to male progeny of the 69 top-producing Arabian stallions in the world is 53 to 47, indicating that the occurrence of genetic defects affecting the sex ratio such as the XY sex-reversal syndrome is relatively infrequent. In nine cases where the sex ratios of stallions deviated significantly from the expected sex ratio, the incidence of female infertility also increased. Cytogenetic screening of young animals would provide for early detection and avoid the expense and disappointment of continuous breeding attempts. Just as importantly, it would aid in the reduction and the possible elimination of this genetic condition from breeding herds.