Trypanosomiasis-induced infertility in dromedary (Camelus dromedarius) bulls: changes in plasma steroids concentration and semen characteristics.

The effect of Trypanosomiasis on concentrations of plasma steroids and semen characteristics was studied in 24 dromedary bulls. Based upon the parasitological and serological diagnosis, 18 bulls were found infected with Trypanosoma evansi (Group 2) and six were found to be free from infection and served as controls (Group 1). The infected animals exhibited signs of anaemia indicated by the decrease of packed cell volume (PCV) and haemoglobin concentration (Hb), pale mucus membranes, weight loss, lethargy, weakness and dullness. However, five animals (27.8%) of the infected group revealed elevated rectal temperatures and three animals (16.7%) revealed testicular degeneration upon palpation of their scrotal contents. Concentrations of plasma oestradiol-17beta (86.5 +/- 8.6 pg/ml versus 232.5 +/- 74.4 pg/ml) and testosterone (4.8 +/- 0.7 ng/ml versus 2.7 +/- 1.5 ng/ml) were significantly different (P < 0.05) between the control and infected bulls. Evaluation of the semen collected by electroejaculation and evaluated by a computerized cell motion analyzer revealed normal semen characteristics in the control animals compared to deteriorated ones in the infected bulls. There were highly significant (P < 0.01) decreases in sperm count (12.2 +/- 1.3/ml versus 6.5 +/- 4.9 x 10(6)/ml), motility percentage (68.2 +/- 6.7% versus 27.4 +/-15.6%), percentage of live spermatozoa (73.2 +/- 8.3% versus 35.8 +/- 8.2%) and increases in percentage of morphological abnormalities (3.3 +/- 0.6% versus 15.9 +/- 1.0%) in the infected group. An examination of the plasma hormonal profiles and semen characteristics in the infected bulls indicated that altered Sertoli cell function due to formation of immune complexes in four bulls (Group 2A), pituitary dysfunction in six bulls (Group 2B), testicular degeneration in three bulls (Group 2C) and finally trypanotolerancy in five bulls (Group 2D) are possible factors responsible for poor semen characteristics and infertility induced by T. evansi infection in dromedary bulls.

Intratesticular morphometric, cellular and endocrine changes in dromedary bulls exhibiting azoospermia.

Twenty bulls, aged 7-12 years and selected from six dromedary farms were used in this study. Fifteen previously fertile animals were divided into fertile (controls) and infertile groups on the basis of abnormal scrotal contents following palpation and azoospermic ejaculates collected by electroejaculation. An examination of the clinical and histological findings as well as the testicular patterns of oestradiol-17beta, testosterone and histamine indicated that three bulls displayed normal ranges comparable to the controls but with bilateral spermatocoeles in the caput epididymides in conjunction with the soft texture of the testicles. Seven bulls showed moderate testicular firmness and springiness, a marked increase in testicular oestradiol-17beta and histamine concentrations, and increases in surface area, density of mast cells and percentages of seminiferous tubules containing premeiotic spermatogenic cells as well as decreases in testicular testosterone concentrations, surface area of Leydig cells and diameter of the seminiferous tubules. The remaining five infertile animals had small hard testicles, supranormal testicular testosterone concentrations, baseline values of testicular oestradiol-17beta and histamine, decreased numbers of Sertoli and mast cells, with a predominance (98.2%) of seminiferous tubules containing spermatogonia resting on a thickened tubular basement membrane. The results provide information on the relationship between gonadotrophin, testicular oestrogen, androgens and histamine as well as spermatogenesis in normal and azoospermic dromedary bulls.

Intratesticular morphometric, cellular and endocrine changes around the pubertal period in dromedary camels.

We obtained the paired testes from 66 clinically healthy camels during two consecutive breeding seasons. Testicular tissues were examined for peripubertal changes in histological structure as well as spermatogenic and steroidogenic activities. Cellular sizes (length microm x width microm) increased linearly (P< 0.05) throughout the first three years of the animal's life for Leydig cells and between two and a half and five years of age for Sertoli cells. A clear increase in the percentage of tubules demonstrating primary and secondary spermatocytes occurred between less than one and five years and a cohort of elongated spermatids was produced in 3.5 +/- 0.2% tubules in males of two and a half years old; the appearance of spermatozoa in 3.1 +/- 0.3% tubules was evident six months later. The basal values for intratesticular and plasma concentrations of oestradiol-17 beta and testosterone respectively, were measured in all animals up to one and a half years for oestradiol-17 beta and three years for testosterone. Thereafter, both steroids increased markedly (P< 0.01) peaking to 269.5 +/-27.1 pg/g and 83.4 +/- 8.3 pg/mL at three years for oestradiol-17 beta and to 164.7 +/- 16.8 ng/g and 6.8 +/- 0.7 ng/mL at five years for testosterone. The results suggested that a steroid hormonal shift around four and a half to five years of age could demarcate the beginning of pubertal period which culminates with the production of the first ejaculum containing higher concentrations of spermatozoa by dromedary camels of six years old.

Gonadotrophin releasing hormone treatment of Holstein cows with follicular cysts monitored by skim milk progesterone determination.

Progesterone was assayed in skim milk fraction of 38 cystic cows, 26 (68.4%) of which had basal ( < 0.5 ng/ml) progesterone concentrations and were diagnosed as having follicular cysts. These cows were allotted at random to one of 3 treatments: (1) a sham injection of sterile water in 7 cows as controls; (2) a single injection (1 mg) of GnRH analog in 8 cows; (3) double injections (1 mg) of GnRH analog at 7-day interval in 11 cows. According to rectal palpation confirmed by skim milk progesterone determination, the double injection group responded well (P < 0.05) compared with the single injection and control groups (81.8% vs 62.5 vs 42.9%). The interval calving to 1st insemination, interval treatment to conception and interval calving to conception were significantly (P < 0.01) shorter in the double injection group than in the other 2 groups. Also, the conception rate to first insemination was significantly (P < 0.05) higher (63.6% vs 37.5% vs 42.9%). The data provide evidence for reduction in infertility and reproductive disorders in cystic cows given double injections of GnRH.

Plasma progesterone, oestradiol-17 beta, oestrone sulphate, corticosteroids and a metabolite of PGF2 alpha: evolution throughout pregnancy, before, during and after parturition in buffalo cows.

The concentration of plasma progesterone, oestradiol-17 beta, oestrone sulphate, corticosteroids and 13,14-dihydro-15-ketoprostaglandin F2 alpha (PGFM) was measured in 12 buffalo cows during the whole period of gestation, around parturition and for 15 d postpartum. The concentration of progesterone and oestradiol-17 beta increased slightly during the first 2 months (3.5 +/- ng/ml) and 4 months (14.8 +/- 2.1 pg/ml) of pregnancy, respectively. Their values remained consistently below these levels until near the end of the pregnancy period when progesterone concentrations decreased significantly (P < 0.05) at d 7 prepartum (0.9 +/- 0.1 ng/ml) and oestradiol-17 beta increased markedly (P < 0.01) at d 10 prepartum (26.3 +/- 2.6 pg/ml). Progesterone showed basal values (< 0.5 ng/ml) from d 4 prepartum to d 15 postpartum. Oestradiol-17 beta concentrations were maximal (82.8 +/- 3.6 pg/ml) during labour and returned to their basal values (< 12 pg/ml) at d 5 postpartum. The concentrations of oestrone sulphate remained low (< 140 pg/ml) during the first half of gestation period. It increased sharply (P < 0.01) thereafter to 5,620 +/- 116.5 pg/ml by 30 d prepartum and afterwards declined to about 50% of this value before calving reaching basal level (< 80 pg/ml) at d 2 postpartum. The concentration of corticosteroids fluctuated narrowly (1.7 +/- 0.3 ng/ml) throughout gestation, increasing significantly (P < 0.05) at d 12 prepartum (5.3 +/- 1.8 ng/ml) and peaking to 16.8 +/- 3.2 ng/ml at the moment of delivery. Its value declined below 3 ng/ml from d 3 onwards postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)

Sequential changes in plasma progesterone, total oestrogens and corticosteroids in the cow throughout pregnancy and around parturition.

Blood samples were taken thrice weekly for 2 weeks from 33 pregnant cows in nine groups, 1 month apart, and twice daily for 8 days commencing 1 week before parturition from eight cows. Plasma progesterone and total oestrogens were quantified by validated radioimmunoassays and total corticosteroids by a competitive protein binding technique. During the first 3 months of pregnancy, no remarkable changes were observed for the three hormones studied. From the fourth month on, concentrations of progesterone and total corticosteroids decreased significantly (P less than 0.05) and remained fairly constant until the ninth month. Values of total oestrogens increased significantly (P less than 0.05) from the fourth to the sixth month and thereafter remained unchanged. In the periparturient cows, progesterone levels decreased linearly (P less than 0.01) during the 3 days preceding delivery. Concentrations of total oestrogens rose sharply from day -5 and peaked at calving. Values of total corticosteroids increased dramatically on the sixth day and also at 24 hours before parturition. These results suggest that, contrary to earlier studies, plasma corticosteroids could have a primary key role for triggering parturition in cows.

Sequential changes in plasma progesterone, total oestrogens and corticosteroids in cow throughout pregnancy and around parturition.

Blood samples were taken thrice a week for 2 weeks from 33 pregnant cows in 9 groups, 1 month apart. In addition, blood samples were collected twice daily 1 week from 8 cows before parturition. Plasma progesterone and total oestrogens were quantified by validated radioimmunoassays and total corticosteroids by a competitive protein binding technique. During the 1st 3 month of pregnancy, no remarkable changes were observed from the 3 hormones studied. From the 4th month on, concentrations of progesterone and total corticosteroids decreased significantly (P less than 0.05) and remained fairly constant until the 9th month. Values of total oestrogens increased significantly (P less than 0.05) from the 4th to 6th months and stayed unchanged afterwards. Progesterone levels in periparturient cows decreased linearly (P less than 0.01) during 3 days preceding delivery. Concentrations of total oestrogens rose sharply from day -5 and peaked at calving. Values of total corticosteroids increased dramatically on the 6th day and 24 hours before parturition. The results obtained suggest that in contrast to studies cited earlier plasma corticosteroids could play a key role for triggering parturition in cows.