No abstract

The objective of this study was to detect the influence of age, breed and season on sexual behaviour, testosterone concentrations and scrotal circumference in Egyptian rams. The study was carried out at agricultural research center belonging to Minia University, Shosha village, Samalut city, El-Minia. Ten crossbred and five adult Ossimi rams were used during this study. Every ram was allowed to breed two ewes to evaluate its sexual behaviour for a twenty minutes test. Blood samples were collected three times per season at two weeks interval from each ram during the period of experiment to measure testosterone concentrations. Also, scrotal circumference was measured at the same frequency and time interval as blood samples. Sexual behaviour was better in old rams than young ones (p<0.01), but it was not affected by breed or season (p>0.05). Serum testosterone level was higher at autumn (7.13±02.9 ng/ml) than at winter (5.54±0.29 ng/ml) in crossbred rams (p<0.01), while in Ossimi rams, higher level was obtained in spring (8.24±.39 ng/ml) than in summer (3.99±0.40 ng/ml). Mean scrotal circumference was higher in older rams (30.20±1.20 cm) than younger rams (22.53±1.27 cm). There was no significant difference for measures of scrotal circumference between crossbred rams (30.86±1.09 cm) and Ossimi rams (30.93±1.06 cm). Season had no significant effect on scrotal circumference in crossbred rams, whereas in Ossimi rams the effect of season was significantly obvious with the highest and lowest values were recorded in spring (31.0±1.05 cm) and winter (30.60±1.17 cm) respectively. It could be concluded from this study that the age of rams had a great influence on their sexual behaviour and scrotal circumference, while the effect of breed and season on sexual behaviour and scrotal circumference was not clear.

Sheep breeds raised in Egypt are used for meat production primarily. However, they are classified as low-prolific breeds (Marai et al., 2009), the low prolificacy of Egyptian ewes may be due to low ovulation rate (Hashem and El-Zarkouny, 2014; Ali et al., 2006). Ossimi sheep is one of the most popular breeds in Egypt which are considered small to medium sized breed (Elshennawy, 1995). Improving the reproductive performance of ewes will increase the number of lambs born which is considered an important demand in the development of sheep production in Egypt. Moreover, nutrition level is one of the most important factors which can influence reproductive performance of sheep and goat (Scaramuzzi et al., 2006; Shahneh et al., 2008). Furthermore, feed supplementation just before ovulation for a short-term period or long-term period could improve the reproductive performance of ewes (Senosy et al., 2013; Habibizad et al., 2015). Also, dietary supplementation with energy and protein sources before mating improves reproductive efficiency and ovulation rate in sheep (Robinson et al., 2002; Keisler and Buckrell, 1997). Flushing is a practice that aims to increase the number of ovulations and improve the fertility in the herd by obtaining a larger number of multiple births (Chagas et al., 2007); it is a known management program for increasing sheep reproductive performance during the breeding season (El-Ella, 2006; Godfrey et al., 2003; Nottle et al., 1997). Conversely, flushing does not always improve the lambing performance (Croker et al., 1985). Delayed estrus activity and ovulation (Gunn et al., 1979), failure of fertilization (Restall et al., 1978) and death of embryos (Rhind et al., 1989) perhaps the consequences of failure of flushing the ewes. The current study aims to investigate the reproductive performance of ewes through flushing with corn and soybean as an energy and protein sources respectively.

Sheep are considered one of the most important farm animals after cattle as a source of red meat all over the world which contribute to about 6 % of the total red meat produced. Sheep are considered a paramount component of livestock production in Egypt; accounts for approximately 30% of total agricultural income (Elshazly and Youngs, 2019). The total population of sheep in Egypt has increased notably in the last two decades to reach about 5.69 million heads in 2019; this increase was attributed to their grazing ability and their need to very low amount of concentrate food (Elshazly and Youngs, 2019). One of the most common breeds of sheep in Egypt isOssimi breed which characterized by extended breeding season, high fertility and low prolificacy (Gabr et al., 2016; Emeash and Mostafa, 2010; Almahdy et al., 2000). Also, it is considered small to medium sized breed (Elshennawy, 1995); its population is over 514,000 heads and it is found in South of Nile Delta (Galal et al., 2005). Improving the reproductive performance of ewes will increase the number of lambs born which is considered an important demand in the development of sheep production in Egypt (Mostafa and Farghal, 2022). Ovulation rate in sheep can be improved by giving GnRH at different times such as at the onset of estrus (Naqvi and Gulyani, 1998) or two days after the second dose of PGF2 alpha (Sirjani et al., 2012) or four days after insemination (Fernandez et al., 2019). It was reported that exogenous GnRH treatment immediately after insemination increased the multiple birth rates of low prolific ewes through enhancing ovulation (Türk et al., 2008). Treatment with GnRH agonists results in an endogenous release of LH surge within one to four hours post-administration (Cam and Kuran, 2004; Cavalcanti et al., 2012). This surge is essential for the occurrence of many critical reproductive Department of Animal Behavior,