Path: utzoo!attcan!uunet!kitty!larry
From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.bio
Subject: Re: Which end of a cow smells worse?
Summary: Moo, belch, CO2 and CH4
Message-ID: <3826@kitty.UUCP>
Date: 3 Jul 90 03:52:29 GMT
References: <1990Jun30.191814.13908@agate.berkeley.edu> <720.268e3e5c@desire.wright.edu>
Organization: Recognition Research Corp., Clarence, NY
Lines: 65

In article <720.268e3e5c@desire.wright.edu>, sbishop@desire.wright.edu writes:
> > This question came up in ca.environment.  I understand that cows
> > produce a lot of methane because they ruminate.  However, there is
> > disagreement as to which exit the methane uses.  Someone in
> > ca.environment said it was definitely the front end, while an old
> > article in the Economist about air pollution definitely indicated it
> > was the rear end.
> 
> Giggle, giggle, I'm sorry but as a farmer's daughter I thought this was
> hilarious.  Anyone who has spent any time around cows KNOWS that the rear
> smells much worse than the front!

	I find the incorrect information in your reply just as hilarious; I
can believe that you are a "farmer's daughter" since it is painfully obvious
that you are neither a "veterinarian's daughter" nor a "chemist's daughter".

	:-)

	As an initial point of information, methane is essentially odorless
and tastless - whatever anyone claims to "smell" around a cow is NOT methane!

	The vast majority of methane is not only produced in the rumen, but
is eliminated through eructation.  The "Economist" article referred to by
the original poster is incorrect as to the principal exit mechanism for
methane in cows.  Cows eructate at a rate of 1 to 3 times per minute; any
observant person who has been around cows should realize that.

	An immense amount of microbial activity occurs in the rumen, with
such activity being responsible for the digestion of at least 75% of all
ingested solids.  A typical composition of rumen gas is 65% carbon dioxide,
25% methane, with the balance being nitrogen, oxygen, hydrogen and hydrogen
sulfide.  It is the hydrogen sulfide which is primarily responsible for the
odor of "cow breath" and, for that matter, "cow pies" :-).  These rumen
gases are produced by both bacterial metabolism and the action of salivary
bicarbonate (releases carbon dioxide).

	Cow feces smells worse because not only is hydrogen sulfide still
present, but so are indole and methyl indole (skatole), which result from
subsequent digestion in the small and large intestines.

> I don't think the methane comes from the
> ruminant.  It comes from MANURE!  Somehow the idea of cows belching methane
> just doesn't get it.

	Sorry, but what you state is simply not true.  You don't have to
take my word for this, however; just consult any textbook on veterinary
physiology, such as the classic "Duke's Physiology of Domestic Animals".

> When you burp can you light the resulting gas?

	People don't burp methane, but *cows* do.  However, the presence
of 65% carbon dioxide in rumen gas goes a long way towards quenching any
attempt at ignition.  It is possible to collect cow feces and extract
the methane for ignition; this is particularly facilitated since methane
is lighter than air, while carbon dioxide (also produced by feces) is
heavier than air.

> Why don't some of you city types go spend some time around cows?  

	I have, thank you; I have lived in a rural area with my own large
(and small) animals for the past 19 years.

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
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