The ritual has taken place on the first Saturday of May for several centuries, in the belief that the blessings would protect the animals from disease.

This year, they were also meant to hasten rain.

"It's a ceremony of strong belief in which the people have much faith, and at this moment it serves also to ask God for help in resolving the catastrophe of drought for our animals," said spectator Antonio Borges, a pensioner.

Hundreds of cattle, goats and sheep have starved this year as a severe drought has left usually lush farmland dry and grassless, particularly in the breadbasket Alentejo and the southern Algarve resort regions.

Livestock producers say hundreds of farm animals are dying because grazing is scarce and farmers can't afford to buy feed.

Rainfall recorded since October has been less than half of average levels and some areas now have restrictions on irrigation.

Dams in the south of Portugal hold less than half their water capacity and authorities worry the drought will affect the high tourist season in the Algarve, where thousands of foreign tourists flock to beaches every summer.

Portugal has asked for cash advances from the European Union to help farmers buy feed, as well as EU subsidies for suckler cows, goats and sheep and to pay for transportation of grains from excess stocks in Hungary.

In neighbouring Spain, ministers agreed to set aside 300 million euros ($390 million) on Friday to guarantee the country's taps do not run dry this summer after the driest winter since records began.