If suddenly 50% of the carnivorous humans turned vegans

What would happen if a rampant virus infecting food animals turned omnivores into zombies?
 
Eventually the number of farm animals would decline to adjust for the decrease in demand. Also, the total amount of greenhouse gasses emitted by farm animals would decrease as well.

Of course, such a senario is unlikely.
 
Eventually the number of farm animals would decline to adjust for the decrease in demand. Also, the total amount of greenhouse gasses emitted by farm animals would decrease as well.

Of course, such a senario is unlikely.
it will be difficult for farmers to meet supply to demand as they will need an increase in production of crops and vegetables. somewhere world will face the shortage of food which may lead to death due to starvation.