The Indian government has banned the sale of cows and buffaloes for slaughter in a move to protect animals considered holy by many Hindus.
State governments and industry bodies have criticized the ban as a blow to beef and leather exports that will also leave hundreds of thousands jobless and deprive millions of Christians, Muslims and poor Hindus of a cheap source of protein.
The rules that took effect Friday require that cattle traders pledge that any cows or buffalos sold are not intended for slaughter.
Eleven of India's 29 states are objecting, with at least one planning a challenge in court. Some have said the federal government's ban infringes on their commercial autonomy, and others are calling for a nationwide protest.