The relationship between environmental conditions and reproduction has been in sight of research. Therefore, there has been a growing interest in effect of climate change, global warming and subsequently environmental heat stress on gametes in last decades. Thus, the present study was designed to investigate the effect of environmental heat stress on Kıvırcık ram sperm parameters. In this study, semen samples (n=72) were collected from six mature rams during a 12-month study period. The temperature and relative humidity of animal box were controlled daily. The mean monthly temperature humidity index (THI) values were calculated to determine heat stress and control periods. According to the mean monthly THI values, the 36 of 72 ejaculates, which were collected between May and October, were classified as heat stress period samples. The others (n=36), which were collected between November and April, were considered as control period samples. The heat stress period sperm samples had lower sperm concentration, motility, viability, membrane integrity and higher abnormal sperm rate compared to control period sperm samples (P< 0.05). Semen volume, sperm DNA integrity and the ability of sperm to undergo acrosome reaction were detected similar between the heat stress and control periods. In conclusion, environmental heat stress was found deleterious for some sperm parameters in Kıvırcık rams.

The influence of sericin supplementation and chilling temperatures (4 and 15 °C) on the short-term storage quality and fertility of rabbit semen was assessed over 72 h of storage. In experiment 1, pooled semen (five replications) was diluted to a concentration of 50 M mL⁻¹, and assigned to control, 0.1%, and 0.5% sericin groups, stored at 4 or 15 °C. Sperm motility, sperm kinematics, viability, and membrane and acrosome integrity were assessed at 0, 24, 48, and 72 h of storage. Experiments 2 and 3 were conducted to observe the effect of sericin on bacterial growth and in vivo fertility. The results of experiment 1 showed that sericin treatment, storage temperature, and storage duration influenced progressive and total sperm motility. The storage duration affected all sperm kinematics variables, whereas VCL, VSL, VAP, and BCF sperm kinematics altered in response to sericin treatment and storage temperature. Similarly, significant effects of sericin treatment, storage temperature, and storage duration were observed for acrosome integrity, sperm membrane integrity, and sperm viability. The results of experiment 2 indicated the antimicrobial effects of sericin when sperm were stored at 15 °C for 72 h. While promising pregnancy outcomes were observed with sericin-treated sperm for 72 h, these results were not significantly different. This study conclusively demonstrates that sericin treatment enhances the quality of rabbit semen when stored at lower temperatures for longer durations. The antimicrobial effects of sericin could be a contributing factor to the improved in vitro and in vivo fertility of rabbit sperm.