It comes soon after similar protests by Greek farmers.
Livestock and dairy farmers have been hit hard by declining prices and losses.
They blocked access to the port city of La Rochelle and more than 100 closed a highways near the city of Lorient in the west, said Thierry Coue, head of the regional chapter of farm union FNSEA.
In La Rochelle on the Atlantic coast, about 100 livestock farmers and grain producers blocked entry to the city from the east, said local FNSEA chairman Francois Avrard.
Bankruptcies last year rose to the highest since at least 1998, led by beef cattle and dairy producers, according to data analysis firm Altares. French raw-milk prices dropped 17 percent in the past two years, while beef prices that farmers say don’t cover costs have fallen 3.5 percent in the period, European Union data show.
The declines came as rising milk output in Europe and New Zealand coincided with a slowdown in Chinese dairy demand, while growth in beef production has outpaced usage.
“Incomes are catastrophic, particularly in red meat and milk,” Coue said. “Today it’s no longer a crisis, this is social distress. People are at the end of their wits.”