My A level Biology students get to use the word “fart” in exams which is something I feel they should be excited about. What other subject would let you get away with that? The farts in question are emitted from the rear ends of cows and are said to contain significant amounts of methane, an important greenhouse gas. Technically, the gas is much more abundant in cow burps but the word “burp” doesn´t quite have the same appeal. This methane is a by-product of the complex process of cellulose digestion and is actually produced by microorganisms residing in the cow´s intestines rather than the cow itself.

Whichever end of the cow the gas exits, the contribution of methane to the atmosphere by the combined emissions of the all the world´s cattle really add up. The sums go something like this: multiply the world population of cows (about 1.5 billion) by how much methane each produces (about 100 kg per year) and you get an answer which has lots and lots of zeroes.

Now, I don´t have it in for cows. Au contraire, I am very fond of them. Cows are big and cool and they give us lots of nice things like meat and milk and cheese. Nevertheless there are problems with having lots and lots of them.

Harry Abbott was telling me last night about the potential environmental problems which could result from the large increase in dairy farming in New Zealand. The wastes of cattle washing into rivers can be very damaging to water quality and, of course, for the world famous trout which swim around in them. There are laws about preventing cattle from getting too close to the rivers but they are not always respected. This is something that Harry and his son Keith have seen first hand.

It is not a small problem. Harry sent me a couple of articles indicating the scale of the problem. Each cow produces about 120 pounds of waste each day, the equivalent of more than 20 people but with no sewers or treatment facilities and a modest herd of 200 cows produces the equivalent waste of a human population of between 5 and 10 thousand. Fish and Game New Zealand are fighting the case for the environment and the public seems to be with them.

Here is a little extract from a recent Fish and Game New Zealand newsletter:

“There is no question in the minds of the general public and industry alike that New Zealand’s unique point of difference, in terms of how it defines itself as a nation and differentiates its products in world markets, centres around its natural environment. New Zealand’s “clean and green/100% Pure” image is promoted extensively as a global brand”

This is now under threat.

All this seems to leave the New Zealanders with the problem of balancing the economic benefits from the dairy industry farming industry which has huge export potential, particularly to China, with the potential damage to New Zealand´s greatest asset, a relatively pristine environment and rivers that guys like me, on the other side of the world, dream about fishing one day.

I hope they get this right.