Changes in the concentration of serum cortisol in blood samples of twenty healthy West African Dwarf (WAD) bucks were determined during electro-ejaculation. The animals were randomly assigned to one of two treatment groups. Group I consisted of bucks that had rectal probe inserted but were not electroejaculated (NEE), and group II consisted of bucks that were electroejaculated (EE) in the morning (0900hr), afternoon (1400hr) and late afternoon (1800hr). The results showed that serum cortisol values found in both groups were similar (P>0.05). Increase in cortisol levels were observed (P<0.05) in the afternoon in both EE and NEE animals in comparison with morning and late afternoon. The findings of this study indicate that the increase observed in cortisol concentrations in the afternoon in both groups reflects stress stimuli due to slight increase in ambient temperature.

Freshwater whirligig beetles are important macroinvertebrates that help maintain freshwater quality by removing dead insects from the surfaces of lakes, ponds, or streams. In this study, we investigated the response of the whirligig beetle, Orectogyrus alluaudi to copper (Cu) and zinc (Zn) by assessing their survival and biochemical responses after 7 days of the whirligig beetle exposure to the metals. Copper significantly reduced the survival of the beetles with LC50 (median lethal concentration) of 223–100 mg L− 1 at 24 to 168 hours of exposure. However, the LC50 of Zn was only significant at 72 h (482 mg L− 1) to 168 h (150 mg L− 1). Copper, at the lowest exposure concentration of 15 mg L− 1, induced oxidative stress on the beetles by significantly increasing the level of malondialdehyde [MDA], a biomarker of lipid peroxidation. There was also significant glutathione [GSH] reduction at the low Cu concentration. However, Zn had no significant effect on the oxidative stress response of the beetles. This study showed that O. alluaudi is less sensitive to copper and zinc via dermal exposure routes than other aquatic invertebrates. Therefore, an alternative way of exposure via the ingestion of contaminated food might be an important exposure pathway to assess the toxicity of metals on the beetles.