Answer:
The country that was responsible for introducing livestock and cattle ranching in the southwest was Spain.
Step-by-step explanation:
The Spanish introduced the first livestock and cattle heads into the region of Texas, that would later lead to the development of cattle ranching. Spain and France were battling over the territory west of the Mississippi River and in order to stop the French from expanding, the Spanish introduced their famous "missions". Priests, soldiers, colonists and over 5 thousand head of Spanish cattle were sent to this territory. When France lost the French and Indian War, these missions were abandoned and the cattle ranching activity started as a lasting profitable activity.