Seasonal variation of thyroxine concentration in Karagouniko and Chios rams in temperate environmental conditions

It is well known that the concentration of the thyroid hormone thyroxine increases as day length increases, and the other way around, in Karagouniko and Chios ewes but based on openly international English literature, nothing is known about this hormone on the rams of the breeds mentioned above concerning a meticulous analysis of their aerial environment. So from this perspective, the current research was conducted to investigate the thyroxine concentrations of Karagouniko and Chios rams, taking into account two periods, January-June and July-November, when the day length was increasing and decreasing, respectively. Apart from photoperiod, the meteorological variables air temperature, relative humidity, and sunshine were taken into consideration in the farm of the Artificial Insemination Center of Karditsa (39021΄18΄΄N, 21054΄19΄΄E), Greece (temperate climate zone), where the experimental animals raised. The possible change of thyroxine concentration in both sheep breeds and the possible changes of the abovementioned meteorological variables between the examined periods were detected using t-tests. Higher thyroxine values (P < 0.05) were confirmed in JanuaryJune (55.11 ng/ml in Karagouniko and 47.72 ng/ml in Chios rams), in comparison to July-November (49.03 ng/ml in Karagouniko and 44.14 ng/ml in Chios rams). Air temperature and sunshine followed a reverse course (P < 0.05). In both periods, Karagouniko rams were characterized by higher concentrations of thyroxine than Chios rams (P < 0.01). Our results add more insight into the physiology of Karagouniko and Chios sheep related to thyroxine and temperate aerial environment.

Blood serum triiodothyronine in Karagouniko and Chios rams as affected by season in a temperate environment

The current research investigated triiodothyronine concentrations in Karagouniko and Chios rams in a temperate climate zone, considering the periods January-June and July-November, characterized by a gradual increase and decrease of daylight length, respectively. The animals raised in the farm of the Artificial Insemination Center of Karditsa (39021΄18΄΄N, 21054΄19΄΄E), Greece, and the meteorological variables air temperature, relative humidity, and sunshine, as well as photoperiod, were considered for a more detailed analysis. T-tests were used to detect possible changes in the concentration of triiodothyronine in both sheep breeds and in the abovementioned meteorological variables. January-June coincided with significantly higher (P < 0.05) triiodothyronine concentrations in Karagouniko and Chios rams (0.82 ng/ml and 0.77 ng/ml, respectively) compared to July-November (0.72 ng/ml in Karagouniko and 0.67 ng/ml in Chios rams). Air temperature and sunshine followed the opposite pattern (P < 0.05). Karagouniko rams showed higher triiodothyronine concentrations than Chios rams, irrespective of the season. Our findings shed light on an important aspect of the thyroid gland function in Karagouniko and Chios sheep under temperate environmental conditions.

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21'18''N, 21°54'19''E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.(AU)

Scrotal circumference in Karagouniko and Chios sheep in relation to the aerial environment

Local breeds are a valuable asset in sheep farming systems in Greece and other Mediterranean countries. Among these, Karagouniko and Chios sheep hold a special position, participating in numerous genetic improvement programs, but a research gap exists on their scrotal circumference (SC) in relation to the environmental parameters photoperiod (PHOTO), air temperature, sunshine and rainfall. Therefore, four seasons were examined: April-June and July-September (Long days, increasing and decreasing photoperiod length, respectively), and October-December and January-March (Short days, decreasing and increasing photoperiod length, respectively). Repeated measures analysis of variance and linear correlation analysis were used to investigate the effect of the period on SC and the relationships of SC and each of the environmental parameters above, respectively, in both breeds. Also, independent t-tests were used to investigate SC differences between Karagouniko and Chios. A progressive increase of SC in both breeds coincided with the lowering of PHOTO from April-June to October-December. A significant correlation was confirmed between the SC of each breed and PHOTO, shedding light on the importance of this parameter on SC. Chios sheep had significantly larger (P < 0.05) SC (35.23 cm) than the Karagouniko one (34.59 cm). Better exploitation of these sheep breeds could be derived from the current study's findings.

Effect of seasonally changing aerial environment on testosterone in Karagouniko and Chios sheep

A well-established activity in Greece and other Mediterranean countries is sheep farming. Karagouniko and Chios sheep are promising breeds and targets for the reproductive physiologist's attention. Under this context, part of the reproductive physiology of Karagouniko and Chios was investigated, taking into account the environment. Specifically, four time periods were considered; April-June (Long days, increasing photoperiod length), July-September (Long days, decreasing photoperiod length), October-December (Short days, decreasing photoperiod length), and January-March (Short days, increasing photoperiod length). The effect of the period on the concentration of the testosterone (main male hormone) in rams of the breeds above was studied, by using repeated measures analysis of variance, also taking into account the environmental variables air temperature, relative humidity, sunshine, rainfall, and photoperiod, in the Artificial Insemination Center of Karditsa (39°21’18’’N, 21054’19’’E), Greece. The lowering of photoperiod from April-June to July-September (long days) and afterward, even more to October-December (short days) coincided with a progressive increase of testosterone in both breeds. Photoperiod seems to have a major role in the concentration of Karagouniko and Chios breeds' testosterone compared to the other environmental variables. When considering the whole experimental period, Chios sheep had significantly higher (P < 0.05) testosterone (1.95 ng/ml) than the Karagouniko one (1.55 ng/ml). Our findings could contribute towards the more rational exploitation of the examined sheep breeds.