The Merino is a productive animal developed by man. The genetic history of the Merino is not a linear history of a gene pool selected over time for superior wool or fleece weights, but a history of outcrossing and the selection of material that is productive in the local environment. It is a history where genetic material from one era in the breed's development becomes the foundation material for further development in another era.
Spain became noted for its fine wool (spinning count between 60s and 64s) and built up a fine wool monopoly during the 12th and 16th century, with wool commerce to Flanders and England being a source of income for Castile in the Late Middle Ages.
Most of the flocks known as cabanas or cavanas were owned by nobility or the church; the sheep grazed the Spanish southern plains in winter and the northern highlands in summer. The Mesta was an organization of privileged sheep owners who developed the breed and controlled the migrations.
The three great studs that founded most of the world's Merino flocks were the Royal Escurial flocks, the Negretti and the Paula. The infantado, Montarcos and Aguires studs had an influence on the Vermont bloodlines.
Before the 18th century the export of Merinos from Spain was a crime punishable with death. In the 18th century a new era began, small exportation of Merinos from Spain and local sheep were used as the foundation of Merino flocks in other countries. In 1723 some were exported to Sweden, but the first major consignment of Escurials was sent by Ferdinand VI of Spain to his cousin, Prince Xavier the Elector of Saxony, in 1765. Further exportation of Escurials to Saxony occurred in 1774, to Hungry in 1775 and to Prussia in 1786. Later in 1786 Louis XVI of France received 366 sheep selected from 10 different cavanas, these founded the stud at the Royal Farm at Rambouillet. The Rambouillet stud enjoyed some 'undisclosed' genetic development with some English long-wool genes contributing to the size and wool-type of the French sheep. Though Emperor the Rambouillet stud had an enormous influence on the development of the Australian Merino.
Sir Joseph Banks procured two rams and four ewes in 1787 by way of Portugal and in 1792 purchased 40 Negrettis for King George III, to found the royal flock at Kew. In 1808, 2000 Paulas were imported.
In 1804 John Macarthur (who had been sent back from Australia to England following a duel with Colonel Patterson) brought seven rams and one ewe from the first dispersal sale of King George III stud. In 1805 Macarthur and the sheep returned to Australia, Macarthur to reunite with his wife Elizabeth who had been developing their flock in his absence. Macarthur is considered the father of the Australian Merino industry however in the long term his sheep had very little influence on the development of the Australian Merino.
From 1765 the Germans in Saxony crossed the Spanish Merino with the Saxon sheep to developed a dense, fine type of Merino (spinning count between 70s and 80s) adapted to its new environment. By 1802 the region had four million Saxon Merino sheep, and was becoming the centre for stud Merino breeding, and German wool was the finest in the world.
In 1802, Colonel David Humphreys, United States Ambassador to Spain, initiated the Vermont strain into North America with an importation of 21 rams and 70 ewes from Portugal and a further importation of 100 infantado Merinos in 1808. The British embargo on wool and wool clothing exports to the U.S. prior to the 1812 British/u.S. war led to a "Merino Craze" with William Jarvis of the Diplomatic Corps importing at least 3500 sheep between 1809 to 1811 through Portugal.
The Napoleonic wars (1793-1813) almost destroyed the Spanish Merino industry. The old cavanas were dispersed or slaughtered. From 1810 onwards the merino scene shifted to Germany, the United States and Australia. Between 1810 and 1840 Australia was engaged in a wool trade war with Germany while importing German sheep. By 1840 Australia had won the war mainly because of Germany's preoccupation with fineness.
By 1801 Australia had 33,818 sheep. Macarthur pioneered the introduction of Saxon Merinos with importation from the Electoral flock in 1812. The first Australian wool boom occurred in 1813 when the Great Dividing Range was crossed. During the 1820s there was increasing interest in Merino sheep. In October 1820 Macarthur showed and sold 39 rams, grossing 510/16/5. By 1830 the Australian sheep population was nearly 2 million. In 1823, at the first sheep show held in Australia, a gold medal was awarded to W. Riley ('Raby') for importing the most Saxons, W. Riley also imported Cashmere Goats into Australia.
The Peppin brothers took a different approach to producing a hardier, longer stapled, broader wool sheep. After purchasing Wanganella Station in the Riverina they selected 200 station bred ewes that thrived under local conditions and purchased 100 South Australian ewes bred at Cannally that were sired by an imported Rambouillet ram. The Peppin brothers mainly used Saxon and Rambouillet rams importing four Rambouillet rams in 1860. One of these, 'Emperor,' cut an 11.4 kg (5.1Kg clean) fleece. They ran some Lincoln ewes but their introduction into the flock is undocumented.
In the 1880s, Vermont rams were imported into Australia from the U.S., since many Australian studmen believed these sheep would improve wool cuts, their use spread rapidly. Unfortunately the fleece weight was high but the clean yield low, the greater grease content increased the risk of fly strike, they had lower uneven wool quality, and lower lambing percentages. Their introduction had a devastating effect on many famous fine-wool studs.
The federation drought ( 1901-1903 ) reduced the number of Australian sheep from 72 to 53 million and ended the Vermont era with the Peppin and Murray blood strain becoming dominant in the pastoral and wheat zones of Australia.
In Australia today, a few Saxon and other fine wool German bloodline Merino studs exist in the high rainfall areas. In the pastoral and agriculture country Peppins and Collinsville (21 to 24 micron) are popular. In the drier areas one finds the Collinsville (21 to 24 micron) strains. The development of the merino is entering a new phase, objective fleece measurement and Best Linear Unbiased Prediction is now being used to identify exceptional animals.