Effect of atmospheric pressure on semen parameters in bull sires of modern selection on the day of collection

The publications concerning the effects of atmospheric pressure on the general patterns of metabolism, reproduction and adaptive capability in animals and humans from 1970 to 2015 are reviewed. The analysis could show that all those investigations were carried out on different mammalia species in different years and were fragmentary. Colossal changes in the Earth’s atmosphere occurred over the recent decades, which were caused by the anthropogenic factors; considerable changes in the environment affected the habitats of living organisms. In addition, the rapid development in the livestock farming on the basis of the accelerated selection processes could contribute to the formation of animal breeds characterized by the changed metabolic functions, the affected stress tolerance, and the lower adaptive capabilities. That enabled us to conduct a survey to ascertain the effect of atmospheric pressure variability on the qualitative and quantitative semen parameters for bull sires of a modern selection. The survey was carried out in the Center for Animal Biotechnology and Molecular Diagnostics, the L.K. Ernst All-Russia Research Institute for Animal Husbandry, on the basis of the Head Center for Reproduction of Farm Animals. The collection, evaluation, freezing, thawing, and the use of the pedigree bull sire semen were carried out according to the National Technology (edited by N.M. Reshetnikov and A.I. Abilov, 2008). A total of 472 ejaculates of bull sires aged 2 to 10 years were analyzed in January, 2012. The atmospheric pressure varied in that period as follows: lower 755 mm Hg, from 755 mm Hg to 765 mm Hg, and over 765 mm during the periods of 7 days, 9 days, and 15 days, respectively. The ejaculate volume (ml), concentration (milliard per ml) and motility of spermatozoa with the progressive forward movements (PFM) (grades) were analyzed after the collection, freezing, thawing, and in 5 hours of incubation at 38 °С; the total number of spermatozoa per ejaculate (milliard), sperm defects (%), number of frozen semen doses per ejaculate, and the supposed loss of the semen doses caused by the sperm defects depending on both the variables of atmospheric pressure and the age of animals were examined comparatively. The obtained data were processed; the statistical reliability was calculated by the Stewdent’s t -criterion. It is ascertained that the atmospheric pressure substantially affects the quantity and the quality of the obtained sperm products. These effects can be neatly traced by the number of sperm defects at sampling with defining a statistically valid value (P > 0.001). The bull sires aged 2.5 to 5 years are found to be more adaptive to the effects of various environmental factors. It is determined that the culling rate of the native semen samples by the activity parameter decreases with increasing the atmospheric pressure. The distinct dependency of the decrease in motility of sperm after the incubation at 38 °С from the increase in the atmospheric pressure was revealed. The best value for the number of the extracted spermatozoa was obtained at 760 mm Hg for each of the animal age groups; the lowest number of ejaculates having more than 5 milliard sperms was obtained at 775 mm Hg. Thus, the obtained data allow conclusion about the effects of atmospheric pressure variables on the sperm product parameters. In this case, the age of bull sires is of considerable importance. It is found that the bulls at the age of 2.5-5 years are more adaptive to the effects of various environmental factors. On the basis of the findings, it should be concluded therefore that in the breeding enterprises, the schedule for collecting the semen from the bull sires has to be corrected according to the atmospheric pressure values. The use of bull sires should be limited or the schedule of their exploitation should be shifted at the atmospheric pressure of 775 mm Hg. The scientific novelty of the paper is in that the complex survey focused on the effects of atmospheric pressure variables on the qualitative and quantitative characteristics of the semen parameters in bull sires of the modern selection have been carried out for the first time.