Review regarding the genomic evolution in sheep milk production and their application to improve the selection criteria

Genetic variability of Sheep global population account approximately 1300 breeds very well adapted in a variety of different climates as a result of genetic selection for milk, meat and wool production, (Scherf, 2000). Sheep were chosen to participate on human consumption for being so fitted to the demands of the third world countries to cover the basic necessity for food and clothe with meat, milk, and wool fiber and also because of the suitable requirements for housing and breeding conditions, having a short generation interval and a docile behavior, (Alkass at al., 2017; Ulises, 2020). Even so in time the human necessity for meat and wool decreased in the last 4 decades and the preferences were directed to the beef, pork and chicken and that why the sheep population declined in the last 15 years for the countries with tradition like Australia, New Zealand, USA, France, England, Spain (FAOSTAT, February, 2013). The opportunity that remained this days for sheep industry was for the niche products requirements of the American consumers for organic lamb meat of high quality, cheese specialties and traditional textile as blankets, rugs and clothes. Having in mind these demands researching area was preparing to understand and find out a better possibility to improve and increase constantly the quality of sheep genome. While the productivity was increasing appeared the sensibility of the new sheep breeds to the parasites and the research tendency was to improve this chapter of the genetic markers for internal parasite resistance (Marshall et al., 2011; Matika et al., 2011; Silva et al., 2012). Sheep breeds were also a suitable model for lab experiments and biomedical research with low requirements for housing and having a docile behavior in order to obtain precious information about similar physiological functions for humans, like embryology development, fetal development, immunology, endocrinology, and reproduction. Sheep anatomy and physiology was fitted to explore a few human Genomic era beginning in 2009 when a lot of studies were undertaken in small ruminants to revel the animal genomes and this new technology make possible this achievement with specific tools like ovine SNP chip. First countries with tradition in sheep production that participated and implemented this new technology for Genomic evaluation were Australia, New Zealand followed by France that applied genomics in dairy sheep and goats. Researches were made recently to fill the existent gap for sheep dairy breeds having in mind the examples from dairy cattle from United States of America. The complex mechanism of milk production involves many genes responsible with different tasks. Some of this genes had the expression in the mammary gland. Genomics helps a lot sheep breeders by minimizing genotyping cost with a better understanding of how to maximize benefits of genomic selection. To be able to accomplish worldwide foods necessities for human requirements, we must have in mind the demographic explosion, the climate change and the eminent crises that will appear soon, in agriculture and animal science and start to found sustainable solutions for these problems. Genomic information helps a lot to take the most appropriate decision when is all about how to select an animal that must be genetically conserved, avoiding the biased estimating breeding values and keeping the genetic diversity.