Monthly variations in some reproductive parameters of Barki and Awassi rams throughout 1 year under subtropical conditions 1. Semen characteristics and hormonal levels

Abstract

Fifteen sexually mature rams, five each of Barki, Awassi (I, imported from Syria) and Awassi (LB, locally born in Egypt) were used in this study. Semen was collected monthly from rams for a period of 12 months to study semen characteristics. In addition, blood samples were collected from rams during the four seasons of the year to determine serum triiodothyronine (T3) and testosterone hormones. Results showed that Barki and Awassi (I and LB) rams are continuous breeders as they show sexual desire and produce semen all the year round. However, monthly variations in semen quality were detected. Relative testes volume, ejaculate volume, sperm concentration, total sperm output, sperm motility, percentage of live sperm and serum testosterone level were higher during summer months than at other months of the year. Serum T3 was significantly higher in winter and spring than that observed in summer and autumn. In addition, percentages of dead spermatozoa were higher in winter and early spring than in autumn and summer. Furthermore, summer months showed moderate percentages of abnormal spermatozoa and spermatozoa without intact acrosomes. These results indicate that ram semen quality in the subtropics may be better during summer months than during other months of the year.

Thyroid hormones in small ruminants: effects of endogenous, environmental and nutritional factors

“…Blood TH concentrations were high in spring (increasing daylength) and low in autumn (decreasing daylength), which was not fully explained by the changes in environmental temperature (Figure 2; Buys et al, 1990;Todini et al, 1992; McMillen, 1995: Clariget et al, 1998;Rhind et al, 2000;Taha et al, 2000;Villar et al, 2000a;Merchant and Riach, 2002;Souza et al, 2002; Blaszczyk et al, 2004;Zamiri and Khodaei, 2005;Menegatos et al, 2006;Todini et al, 2006). It seems that when the temperature ranges are not extreme (mild climate, indoor housing, shelter in the night time), the effect of photoperiod and season-dependent TH profiles (mainly related to the daylength changes) are present.…”

“…In the Sahel desert, plasma T3 and T4 levels did not change significantly from the beginning of the cool season (December) until the end of the dry warm season (May), but a highly significant rise of both hormones was observed at the onset of the humid warm season (June) (Assane and Sere, 1990). It can be supposed that an enhanced thyroid activity during the humid warm season in such environments is functional for the animals facing the increased availability of food (quantity and quality), following the seasons characterised by food shortage.Blood TH concentrations were high in spring (increasing daylength) and low in autumn (decreasing daylength), which was not fully explained by the changes in environmental temperature (Figure 2; Buys et al, 1990;Todini et al, 1992; McMillen, 1995: Clariget et al, 1998;Rhind et al, 2000;Taha et al, 2000;Villar et al, 2000a;Merchant and Riach, 2002;Souza et al, 2002; Blaszczyk et al, 2004;Zamiri and Khodaei, 2005;Menegatos et al, 2006;Todini et al, 2006). It seems that when the temperature ranges are not extreme (mild climate, indoor housing, shelter in the night time), the effect of photoperiod and season-dependent TH profiles (mainly related to the daylength changes) are present.…”

Dietary Boron Supplementation and its Impact on Semen Characteristics and Physiological Status of Adult Male Rabbits

“…Many studies have shown that low content of seminal plasma proteins is associated with poor semen quality (White et al, 1987;Ashworth et al, 1994). Taha et al (2000) revealed that there was a positive relationship between semen quality and level of seminal plasma total proteins. Similar results were found by Osama and El-Sahn (2006), they found a positive relationship between increasing seminal plasma total proteins and albumin and increasing total number of sperm output.…”

Testosterone and cortisol patterns and the effects of electro-ejaculation and copulation in Awassi rams

“…The latitudinal location of the current experiment (33 • N) could be partly responsible for shifting the breeding season in summer rather than in autumn. A pronounced increase in testosterone level in spring and summer seasons has been recorded in studies conducted by Olster and Foster (1988) and Taha et al (2000). The previous authors suggested that in mature rams the stimulation of the hypothalamic-pituitary axis begins in spring when photoperiod increases.…”

“…This breed is well adapted to harsh environmental conditions and raised primarily for three types of products: meat, milk and wool (Iniguez and Hilali, 2009). Although seasonality pattern of Awassi rams has been previously reported (Taha et al, 2000;Kridli et al, 2007), little information is available about the seasonal profile of both testosterone and cortisol and the effects of electro-ejaculation and copulation process on Awassi rams. Therefore, the objectives of the current experiments were (1) to determine the seasonal pattern of testosterone and cortisol in Syrian Awassi rams during a period of 1 year and (2) to investigate electro-ejaculation and copulation effects on cortisol and testosterone levels during the breeding and non-breeding season.…”