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Cow is not the only ruminant livestock which produce CH4 gas, though it is a major one. Other livestock is generating CH4 as well, and I shall check up each one of them (if I could find the neccessary information ). How much of CH4 is emitted throughout these livestocks each year?

For time being, let’s look at sheep. After some googling, 2 claims for sheep (so far) are found.

Claim#1: Individual sheep emission rates were highly variable and averaged 19.5 ± 4.8 (SD) g CH4 per sheep per day. (source here)

Thus, a sheep can produce 7.12 kg of CH4 per year.

And, claim#2: New Zealand`s 70 million sheep create 350 million methane gallons daily. (source here)

70 million sheeps for 350 million gallons methane, 5 gallons CH4 per sheep per day, or equivalent to 18.93 L of CH4.

Divide by standard volume molar (22.414 L/mol), the weight of CH4 produced by sheep per day = 0.844 mol x 16 g (CH4 molecular weight) = 13.51 g per day.

In a year, a sheep is producing 4.93 kg CH4. And this value is lower than the claim#1.

As of year 2003, there is around 1 billion, or 1 024 070 182 sheeps (not including the sheep for milk) around the world. Thus, the total annual CH4 emission by sheeps for:

Claim#1: Total CH4 = 1 024 070 182 x 7.12 kg = 7.291 million tonnes.

Claim#2: Total CH4 = 1 024 070 182 x 4.93 kg = 5.049 million tonnes.

Apparently sheep is not emitting much CH4, compared to cow/cattle.

source: FAO, Global Livestock Production and Health Atlas

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.

After cattle/beef cow, now let’s move on to dairy/milking/lactating cow. There are few papers found on the data of CH4 emission by dairy cow.

1. According to this paper‘s finding (paper#1), dairy cow is measured releasing 587 ± 61.3 L CH4 per day. And compared to the values obtained from other references cited: 420L, 500L, 552L and 560L.
2. According to this paper (paper#2), the lactating Holstein dairy cows produced 458.7g CH4 per day.
3. According to this paper from India (paper#3), (i) the milking crossbred cattle produced 106.4g CH4 per day while (ii) the milking indigenous cattle emitted 98.57g CH4 per day.

According o FAO’s statistic, there are 237 928 359 (238 millions) milked cow around the world in 2003.  Thus, the total CH4/methane emission by dairy cow around the world with the summary of all the number above is listed in the table below:

source: FAO, Global Livestock Production and Health Atlas, 2003

More CH4 emission by cattle or beef cow is found! Thefore, I shall continue from the previous post from here.

Claim#3: according to this paper, beef cow produces 262L CH4 per day.

1L CH4 weigh about 0.714g. Thus, the weight of CH4 in 262L CH4 gas is about 187.03g per day.

Or 68.26 kg per year.

Claim#4: from this paper (citing another referecence), “…the average daily CH4 emissions predicted from this SF6 technique (11.6 ± 0.7 L h-1) were similar to those measured using open circuit respiration calorimetry (12.9 ± 0.7 L h-1)”.  

So 2 very close numbers are obtained: (4-a) 11.6L per hour and (4-b) 12.9L per hour. Total CH4 by weight in a year:

Thus, CH4 annual emission by weight is (4-a) 72.54kg or (4-b) 80.67kg.

Claim#5: CH4 from livestock in India is listed in this paper. Methane gas emitted from various type of cattles can be found, and the summary is listed in the table below.

Thus, CH4 emission is (5-a) 36.31kg and (5-b) 32.95kg. Noted that the value here is comparitively much lower than the other value from claim#1-4.

To calculate the total CH4 emission from 1.33 billion cattle/beef cow around the world in 1 year:

Claim#3: Total CH4 = 1.33 x 10^9 x 68.26 kg = 90.78 million tonnes.

Claim#4-a: Total CH4 = 1.33 x 10^9 x 72.54 kg = 96.48 million tonnes.

Claim#4-b: Total CH4 = 1.33 x 10^9 x 80.67 kg = 107.29 million tonnes.

Claim#5-a: Total CH4 = 1.33 x 10^9 x 36.31 kg = 48.29 million tonnes.

Claim#5-b: Total CH4 = 1.33 x 10^9 x 32.95 kg = 43.82 million tonnes.

Combining all the claims found so far, the summary of total CH4 emission by cattle/beef cow in year 2003 is listed in the table below: