This UN site says 5% of actual CO2 and 14% of CO2-equivalent emissions. Cow and pig production emit mostly methane and nitrogen oxide.
https://en.wikipedia.org/wiki/Ruminant#Ruminants_and_climate...
And I'm less sure of this, but I've heard that they cause far less soil erosion compared to cows, as their weight is spread out over a much larger area (i.e. they have big feet). Their populations in some parts of Australia have also reached unsustainable starvation levels, to the point where some State-level governments have initiated culling (i.e. licensed shooting of kangaroos, in a country with very tight gun-control laws).