Heavy metals are highly toxic elements that are present in the environment, especially in water. Mercury chloride (HgCl2) stands out among these compounds because of its strong ability to induce damage to any tissue with which it comes into contact. The gametes of spawning aquatic animals, such as fish, are susceptible to such damage. Thus, our objective was to evaluate the toxic potential of HgCl2 in the capacitation and activation of Rhamdia quelen sperm. Semen was collected from seven males and activated in 58 mM sodium chloride (NaCl) containing 0 (control), 4−10, 7−10, 7−9, and 7−8 M HgCl2. The evaluated variables included motility, vigor, motility time, morphology, membrane integrity, membrane fluidity, mitochondrial functionality, production of reactive oxygen species (ROS), and DNA fragmentation. All evaluated HgCl2 concentrations increased primary pathologies and reduced motility, vigor and motility time. Damage to membrane integrity and fluidity began occurring at a concentration of 7−10 M HgCl2. These results indicate that HgCl2 has a toxic effect on different sites of fish spermatozoa and that sperm motility decreases after exposure to HgCl2, impairing sperm capacitation and activation.

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The objective of this study was to describe emus’ breeding performance in Brazil at different ages, grouped in couples or colonies. The duration of the breeding season and the production of eggs per female housed were recorded, and the productivity and breeding variables were associated with the variation of the photoperiod. The total production of the flock was 180 eggs, and the breeding season lasted 167 days (April-September), a period with an average of 11 h and 11min of daylight. The breeding season lasted 113, 133 and 82 days, the numbers of eggs produced per female were 7.29, 25.67 and 17.3, and productivity values were 31.6, 38.6, and 45.4% in the groups of birds with ages of two, four and seven years, respectively. The breeding season in 2016 occurred between April and August in Brazil. Older birds tended to start breeding later. The production rate observations indicated that earlier peak production was associated with lower egg production potential. Finally, there was a tendency for better breeding performance of birds housed in couples than in groups with more birds.