My experience as an extension agronomist in Sardinia, Italy during blue tongue epidemics in early 2000s is that native sheep with more rustic, less improved genotype suffered lower mortality rates. In an era of global change and emerging vector-borne zoonotic diseases, this may be something to factor in.

In general, landraces are better adapted to local conditions, and hence more efficient and productive given locally available resources.

Resilience to climate change is also an important factor to weigh in -- see pages 50-51 and following:

http://www.fao.org/3/a-i5188e.pdf

You should make some simple studies proving the superiority and adpatability (fertility, fecundity, mortality rate and productions indices...) of local breeds to specific environments in relation to exotic breeds. Normally identify some leader producers helps.

Dear Dr. Teixeira.

My name is Victoria Campos. I am a student from UNAM, FESC. Your dear friend Dr. Alfredo Cuéllar is one of my teachers. He told me that you live in Braga, Portugal. I am doing a research visiting in Porto at the Ciimar. I hope we can met us one day. By the way I am in the  Research in the Project. CYTED 116RT0503 (2016-2019) MARCAS DE CALIDAD DE CARNE Y PRODUCTOS CARNICOS IBEROAMERICANOS (MARCARNE), but I work with molecular biodiversity of creole sheep

Best Regards