Present study was conducted during four seasons of the year, 2008 namely winter (December to February), spring (March to April), summer (May to September) and autumn (October to November). The study was divided into two phases; in first phase a questionnaire survey was conducted on traditional management system of camels and climatic data was collected from three ecological zones under study (Faisalabad, Bhakkar and Attock). In second phase, total 24 mature healthy male camels were used for recording seasonal and ecological changes in the behavior, ultrasonographic structure and biometry of testis and serum biochemistry (steroid hormones and some minerals) at all the zones. Biopsy sampling was done from the camels kept at Faisalabad zone (n=12; 6 in each breeding and non-breeding season) for ultastructural investigations, and slaughterhouse sampling (n=24; 6 sample in each season of the year) was done for morphometrical studies. The period of sexual activity started earlier in November and extended more even up to April at Attk as compared to other zones. Male camels used for breeding even up to 20 years of age at Attk zone. Duration of copulation was up to even 35 min at Attk zone, so it can be derived that the males of Attk zone are more efficient in reproduction as compared to FSD and Bkkr. The degree of most of rutting behavioral signs varies among different seasons and climate of the location. Some behavioral signs were observed as more extensive at Attk and then Bkkr zone as compared to the FSD, in the autumn (October, November) and spring seasons of the year, which revealed that the rutting season started earlier at these locations (Attk and Bkkr) and extended even up to the start of the summer at Attk zone. Biometric studies showed significantly (P<0.01) higher scrotal length and width of the testis during winter and spring season as compared to summer and autumn. Ultrasonographic imaging showed, the parenchyma of the testis as homogenous and moderate echogenic, the testicular capsule was appeared as thick hyper-echoic structure and tunics were identified as hyperechoic lines in both longitudinal and transverse planes, covering the parenchyma. A thin intratunical anechoic linear area was identified, because of fluid between the connective tissue coverings. Mediastinum was visualized as hyperechoic central line in the longitudinal section and a central hyperechoic circular area in transverse plane of the testis. Season had a prominent noticeable effect on the ultrasonic picture of the testis and epididymis at all the experimental zones. Serum testosterone was higher (P<0.01) during the winter season atChapter 2: Review of literature 30 all ecological zones under study, it started decreasing during spring and reached baseline during summer, maintained almost same during autumn at FSD zone however increased again in autumn at Attk and Bkkr zones. This increased level in autumn season was more at Attk as compared to Bkkr zone. Serum estradiol 17- β was higher (P<0.01) during the cooler months including January, February at all the ecological zones, it started declining in the month of March, April and May, little increased level was observed in the month of June but again sloped down in July and remained on baseline in the months of August, September, October and November. Serum concentrations of calcium, iron, sodium and chloride were higher (P<0.01) during the winter and spring as compared to other seasons of the year, while vice versa was true for the serum potassium, as it was recorded as significantly higher during the summer season. Serum testosterone, estradiol, calcium, iron, sodium and chloride were negatively correlated with the average environmental temperature and rainfall while positively correlated with the relative humidity and vice versa for serum potassium levels with some regional variations among different zones. Morphometrical studies showed that the volume, weight of the testis, average diameter of Sertoli cells, volume of intertubular compartment, relative volume of Leydig cells (VLc %), total volume of Leydig cells (TVLc × 10 12 μm 3 ), numbers of Leydig cells ×10 9 per testis and % intertubular tissue in the parenchyma of testis, were significantly (P<0.01) higher during the winter and spring seasons as compared to summer and autumn. However, % area occupied by the seminiferous tubules, % seminiferous tubule / interstitium, and the volume occupied by the seminiferous tubules and diameter of seminiferous tubules were recorded as significantly (P<0.01) higher during summer and autumn as compared to winter and spring seasons. Ultrastructural studies showed highly active Leydig and Sertoli cells during breeding season of camels (cytoplasm was having abundant and developed smooth endoplasmic reticulum (SER), more oval to elongate mitochondria and few fat droplets) and vice versa during the non-breeding season.