The objective of the present work was to obtain pure ovine reproducers.Starting 2010 work began with the sheep herd of the Faculty of Veterinary Medicine and Animal Science of the Universidad Autónoma de Guerrero,located in the municipality of Pungarabato,Guerrero State,México.The faculty is 250 meters above sea level.The climate of the region is warm subhumid,with average temperature between 24 and 30°C,but in the heat season maximum temperatures up to 46°down in the shade.The rainfall regimen is 800-1,200 mm of rainfall per year.The production of sheep in Mexico is characterized mainly by creole animals and crosses are made with pure breeds imported from several European countries and USA.Therefore,there is a need to form local breeds adapted to the climatic conditions and production systems of Mexico.The sheep herd initially had 100 animal of hair,with 70 sheep with their lambs and a reproducer.These animals had phenotype Pelibuey,Black Belly,Doper and Katahdin.As of May 2010,consanguineous crosses were established.During this period the parameters were registered:date and type of birth,weight and sex of the newborn.Data on BW(Birth Weight)of males and females were analyzed by ANOVA(Analysis of Variance)and multiple comparison test was used for the comparison of means(Duncan,1955),with a significance level of P<0.05.The first reproducer was brown tobacco and had antlers,and the females had different phenotypes.Up to the present time,there are twenty studs with their respective descendants,and year 2019 the herd has 100 animals light brown and tobacco with their lambs(30),and a reproducer.The sheep are of medium size with 45 and 60 kg of average weight in females and male,respectively.Out of a total of 326 females and 335 males born,with an average weight of 2.62 kg at birth and a proliferative index of 1.41,20 MEVEZUG males were selected to be used as reproducers in 20 herds distributed in different sheep production units of the state of Guerrero.From the crosses of these breeders to the females of these h