In this paper, we present the results of five years of experimentation on playing at altitude. Since 1940, when the lethal action of dilutor of tartrates on spermatozoa demonstrated to date, we have advanced in the study of reproduction, but since this topic so broad and so much interest for its practical implementation, we believe our results should be considered as a preliminary survey in this study. Each point must be reviewed and analyzed carefully, because of the results obtained in experimental work depends establishing scientific guidelines for the reproduction and development of animal population of our mountain.

The author studies the semen of the rams in its known characteristics, and states the differences found at 4500 mts. of altitude. The very well know fact of reduced birth rate (50 to 60 % versus 100 % at sea level), is due to several factors : The deviations of pH are greater than at sea level. The number of spermatozoids is rather high, but there are young forms frequently seen, with a decrease of their mobility, as well as the presence of white blood cells, epithelial cells, etc. In fact he founds only 26 % of 58 supposedly normal rams, which could be considered suited for reproduction. By means of artificial insemination, and using selected males, he obtained 86,4 % of fertility, the result being very impressive as the ewes served were those so called "machorras" (infertiles). This paper proves, therefore, that the reduced birth rate of sheep at high altitude, is due to a diminishing ...

Until 1940, the prevailing view regarding the declining birth of sheep in the highlands compared to what is obtained at sea level, was based on the belief in the existence of sheep "butch" unable to reproduce. Despite this, farmers employing 5 or 7 acclimated males per 100 sheep, long residence with blood from sheep brought for the Colony; while at sea level, this percentage never exceeded 2 or 3 Yet it was extremely difficult to obtain, with imported animals, a higher reproduction ratio to 30% or 40%, particularly the first year of acclimatization, during which the percentage of fertility fell within 20% with the consequent economic loss.