Sexual behavior, semen characteristics and plasma testosterone level of purebred native Egyptian bulls with emphasis on variations due to seasons and months of the year

The present study utilized 6 sexually mature native Egyptian bulls raised in the National Research Center Farm, nearby Cairo. Bulls were used for collection of a single semen ejaculate / week for a period of one year using artificial vagina. Sexual behavior was measured in term of reaction time and number of mounts per ejaculate. Semen samples were immediately examined after collection for physical, microscopical and chemical properties. Jugular blood samples were collected once in the middle of each month from each bull for assaying testosterone value [Radioimmunoassay]. Results obtained from collection of 312 ejaculates revealed that native Egyptian bulls have reaction time of 41.22 sec and number of mounts per ejaculate of 1.31 with the best parameters during autumn and the poorest parameters during winter. Ejaculate volume [ml.], sperm cell concentration [X10[6] /ml] averaged 3.39, 1181.96 and 4051.180 with the highest values during autumn and the lowest values during spring. Mass motility [0-5] averaged 3.66 with the best value during spring and the lowest during winter. Individual motility and alive sperm percentage were 76.11 and 88.0%, respectively with the highest values during autumn and the lowest values during winter. Sperm abnormalities averaged 12.63% with the best percentage during summer and the highest value during winter. Initial seminal fructose and citric acid concentrations averaged 764.32 and 384.34 mg/dl, respectively with the highest concentrations during autumn and the lowest values during winter and summer, respectively. Sodium and potassium ion concentrations were 180.60 and 108.03 Meq/1, respectively with the highest values during autumn and February, and winter and February, while the lowest values were obtained during spring and June, summer and September, respectively. Plasma testosterone value averaged 4.07 ng/ml with the highest value was obtained during autumn and the lowest value during spring. In conclusion, native Egyptian bulls showed sexual behavior, semen characteristics and plasma testosterone values comparable to those parameters of universal breeds, however, highly significant seasonal and monthly variations were evident with the best results obtained during autumn season and during November and December

Effect of ejaculation on plasma testosterone level of purebred native Egyptian bulls with emphasis on correlations with sexual behavior and semen characteristics

This is study was performed on 6 purebred mature native Egyptian bulls raised in the National Research Centre Experimental Farm nearby Cairo. To investigate the effect of ejaculation on plasma testosterone profile, blood samples were collected before [2 and 1 hr], during and after [1/2, 1, 11/2 and 2 hr] semen collection by means of an artificial vagina. Sexual behavior was evaluated in terms of the reaction time and number of mounts / successful ejaculate. Semen samples were examined and results were correlated with testosterone levels. Testosterone levels were assayed using the radioimmunoassay technique and data were statistically analyzed. Plasma testosterone value [ng/ml] averaged 4.07 +/- 0.43 in purebred native Egyptian bulls. Values obviously decreased after [3.64 +/- 0.17] than before [4.58 +/- 0.23] semen collection. Ejaculation induced more variations in testosterone levels during autumn and less variations during spring. Moreover, correlation coefficients between plasma testosterone level and sexual behavior and semen characteristics of native bulls were recorded. In conclusion, purebred native Egyptian bulls have a comparable blood plasma testosterone level to the universal breeds with obvious individual, monthly and seasonal variations

relationship between plasma progesterone concentration and embryo production in dairy cows superovulated with FSH or PMSG

Fourteen primiparous lactating cows, 3.5 to 4.5 years old in a military dairy farm nearby Cairo [Egypt] were used in this study. Following synchronization, the animals were randomly assigned into two groups; the first group [6 cows] was superovulated with a total dose of 32 mg FSH-P whereas the second group [8 cows] was treated with 3000 iu PMSG. Embryos were collected non-surgically on day 7 [day of estrus = day 0]. Plasma samples were taken from cows of both groups on day-4 [first day of gonadotrophin treatment], day-2 [day of PGF[2] alpha injection], day 0 [day of estrus] days 1,3,5 post-estrus and day 7 [day of recovery] for progesterone assay. The results revealed that FSH was more effective as a superovulatory agent than PMSG. Higher [P < 0.05] ovulalion rate [11.33 +/- 1.85 vs 6.63 +/- 1.14], number of embryos recovered per donor [5.17 +/- 1.20 vs 2.44 +/- 0.45] as well as number of transferable embryos [4.16 +/- 1.01 vs 1.86 +/- 0.42] were obtained from FSH than from PMSG-treated cows. However, more follicles [> 10 mm] were palpated in the PMSG-treated group [2.00 +/- 0.40 vs 0.33 +/- 0.19; P < 0.01]. Coefficients of correlation between progesterone concentration at initiation of superovulalion and each of the ovulation rate, number of embryos recovered and number of transferable embryos were higher in FSH than in PMSG-treated cows. When the data of both groups were pooled, the respective correlations [0.74, 0.69, 0.67] were still highly [P < 0.01] significant. Moreover, significant correlations were estimated between progesterone concentration and the mentioned parameters in FSH group at the day of recovery. This study revealed that measurement of plasma progesterone concentration can serve as a prognostic tool to predict the yield of fertile eggs and quality of embryos

Age-related changes and seasonal variations in the daily sperm production of the stallion

Fifty-six testes were collected from 28 Arab and native stallions [aged 3 to 18 years] along a complete annual cycle to determine the influence of age and season on the daily sperm production [DSP] by a quantitive histological technique. Overall, mean values for testicular measurements, percentage of seminiferous tubules [SNT%], corrected number of spermatids and diameter of SNT/stage I cross-section were given in the text. Estimates of 4.39 x 10[9] sperm/tcstis/day, 8.77 x 10[9] sperm/ stallion/day and 28.45 x 10[6] sperm/g parenchyma were noted, highly significant [P < 0.01] increase with age in these traits was evident up to 13 years old stallions, where peak values of 5.30 x 10[9], 10.60 x 10[9] and 33.67 x 10[6] for the foregoing parameters were achieved. On the other hand, testicular weight, parenchymal weight, number of spermatids per stage I tubule cross-section and DSP/g accounted for 64%, 63%, 67% and 86% of the variation in the DSP/testis, respectively. Age-related changes in the above mentioned parameters were also scrutinized. The onset of breeding season [December-May] in Arab and native horses was associated with a significant increase in testicular weight [13%], parenchymal weight [14%], diameter of SNT/ stage I cross-section [8%], corrected number of spermatids/stage I tubule cross-section [15.%], DSP/testis [27%] and DSP/stallion [27%]. The production of sperm [per testis/day or stallion/day] was lowest [3.66 x 10[9] vs 5.01 x 10[9] and 7.33 x 10[9] vs 10.03 x 10[9]; P<0.01] in the non-breeding season, averaging only 73% of the DSP in the breeding season. Therefore, stallions are capable of producing significantly more spermatozoa [2.70 x 10[9] additional sperm/stallion/day] in the breeding season and could supply sufficient numbers of sperm for insemination of more mates at this time

On spermatogenesis, numbers of Sertoli cells and Leydig cells in stallions as modulated by age and season

The study used 56 testes collected from 28 Arab and native stallions [3-18 years] during a complete annual cycle. The consequences of seasonal and age-related changs in parenchymal weight and in numbers of spermatogonia, young and old primary spermatocytes, round spermatids, Sertoli cells and Leydig cells were evaluated. There were statistically significant seasonal and age effects on parenchymal weight, numbers of Sertoli cells, Leydig cells and spermatogenesis. Seasonal changes in the above testicular parameters were maximal in spring and winter, followed by summer, then reaching their minima in the autumn. The highest values for these criteria were reached by stallions of 6- <13 years, whereas the lowest values were observed later in life. Neither age nor season influenced tlie diameter of Sertoli cell nuclei, Leydig cell or leydig cell nuclei. The mechanisms by which the numbers of both somatic testicular cells fluctuate with the yearly reproductive cycle of the stallion were discussed. Evidence from the present results revealed that numbers of Sertoli cells, germ cells and parenchymal weight were interrelated. Numbers of spermatogonia, Sertoli cells and Leydig cells accounted for 59%, 58% and 48% of the variation in parenchymal weight, respectively. The relationships existed between the number of either of the two somatic testicular cells and spermalogenesis were also scrutinized. The present results emphasize the importance of age and seasonal changes in numbers of Sertoli cells and Leydig cells on regulation of stallions spermatogenesis