Yes, I did it on CO2 emission by human being, CH4 emission by dairy cow, and this time: CO2 by dairy cow! Yes, dairy cow, just like any other animal being, do respiration, and exhale CO2 as well.
From this paper, the lactating cows are emitting 6137 ± 505 L CO2 per day (before correcting the gas emission from manure) or 5756L (value#1) per day (after substraction of CO2 emission from manure). The value of CO2 emission from some other references is cited in the same paper as well: 4940L (value#2), 5396L (value#3) and 6515L (value#4) per day. These 4 values will be used to calculate how much CO2 is released by all the dairy cows in the world in 1 year and is shown with the table below:
And compared this value to human being on earth (as of year 2007), human population is breathing about 1362 million tonnes (case#1) or 2618 million tonnes (case#2) CO2 per year. By comparing the numbers here, dairy cow is pretty much catching up with human being, even though their number 0.238 billion is far less than human population, 6.6 billion.