The first improvements of the pastoral industry of the Pampa are connected with the development of sheep-breeding. Exports of wool began about 1840, and made great progress after 1855 (17,000 tons in 1860, 65,000 tons in 1870). From 1850 to about 1890 the economic returns on sheep-breeding were far better than on cattle-breeding. During the whole of this period the multiplication of sheep farms was only restricted by the supply of workers. The first shepherds had been Basques, in the south of the Buenos Aires province, and Irish, in the north. The owner settled them as small farmers in the _puestos_ on the edge of the ranch, the central part of which was devoted to cattle. They could thus, while they guarded their sheep, see that the limits of the estate were respected, and prevent the cattle from roaming. Wool was for a long time the only product of the sheep-rearing industry. From 1866 onward it was decided to use the hides and tallow also. As the material of the grease-works was cheap, they spread all over the sheep zone. Many ranches had works of their own. From 1867 to 1877 the _saladeros_ that had been built long before for killing cattle undertook the slaughter of sheep on a large scale. The number of sheep sold to the _saladeros_ rose to 3,000,000 a year. In 1880 the first cargoes of frozen mutton were sent abroad. The creation of the grease-works had made no difference to the breeding, but the building of the refrigerators brought about a rapid transformation of the flock. The Lincoln breed, heavier and more meaty, displaced the fine-wool Merinos. This substitution of Lincolns for Merinos is now complete throughout the Pampean region.