Selenium efficiency in preserving sperm quality and testicular characteristics of South African indigenous Zulu Rams exposed to heat stress

Abstract

The purpose of the study was to investigate selenium efficiency in preserving sperm quality and testicular parameters of the hardy South African indigenous Zulu Rams exposed to heat stress. A total of 20 indigenous Zulu rams between the ages of 2–5 years were used for semen collection. The rams were allocated into 4 groups namely: Selenium (Se); Selenium and testicular heat stress (SeTHs); Testicular heat stress (THs) and Control with Each group having five rams. The groups were balanced according to body weight and scrotal circumference. Selenium and SeTHs groups received sodium selenite orally on a bi-weekly basis for a period of 4 months. To induce heat stress, testicular heat insulation bags were wrapped around the testes of the testicular heat insulated (THs) ram group for 49 days to cover the duration of spermatogenesis. Semen was collected weekly from all 20 rams for 3 months while the 1st month was for selenium acclimatization, and testicular measurements were taken bi-weekly. ANOVA was used to separate mean values for sperm quality and Duncan was utilised to compare significant differences using Statistical Analysis Software. It was observed that selenium, SeTHs, and control group obtained similar total sperm motility, while THs group recorded a low (p < 0.05) total sperm motility. SeTHs group had a significantly high (p < 0.05) medium moving (92 ± 3.5) sperm cells as opposed to the other treatment groups. The semen collected from the THs group of rams displayed a significantly higher (p < 0.05) number of immotile sperm cells. The scrotal circumference for the rams supplemented with selenium was smaller (p < 0.05). The current study concluded that induced heat stress compromised the sperm quality parameters such as sperm motility, progressive motility and kinematic parameters. Furthermore, Se supplementation protected sperm cells against testicular heat stress whereby similar sperm quality results were observed in the semen from the group of rams supplemented with selenium including those that received selenium and were exposed to testicular heat insulation.