The aim of this study was to evaluate the seminal characteristics and the physical and functional conditions of native and introduced sheep breeds under the environmental conditions of the Colombian Caribbean. In total, 117 Santa Inés, Dorper, Katahdin and Ovinos de Pelo Colombiano (OPC) rams older than 11 months were evaluated for 14 months. The animals were from 18 farms of the departments of Córdoba, Sucre, Bolívar, Cesar and La Guajira. The physical-functional examinations of the males were carried out, as well as the macroscopic and microscopic characteristics of the semen. There were no differences (p>0.05) between breeds, departments and collection methods for the variables testicular volume, testicular length and width, scrotal circumference and testicular tone. In the humid Caribbean, mass motility was 76.36 ± 6.13% and the sperm concentration was 2707 ± 573x106 sperm/ml...

The sheep populations of the Colombian Caribbean Region are characterized by having a high phenotypic heterogeneity mainly due to the use of Creole animals in crossbreeding with exotic breeds. The aim of this study was to estimate the genetic diversity and the population structure of sheep in this region. In total, 459 sheep from 26 farms in 19 municipalities were selected. The DNA samples were genotyped with the ovine low-density chip (15K). Analyses of molecular variance, genetic diversity and population structure were performed. At the phenotypic level, 65.8% of the sampled animals were assigned to the Criollo population, while 15.7% showed signs of introgression with other commercial breeds (mestizos). The populations presented a high degree of genetic diversity within individuals (90.6%) and low levels of genetic variation between populations (FST = 0.075). This low differentiation,...