From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.bio.food-science
Subject: Re: Raising cattle
Date: Thu, 13 Feb 1997 22:37:58 +0000

In article <E5K0J9.LFA@murdoch.acc.Virginia.EDU>, Laura Ann Young
<lay4a@faraday.clas.Virginia.EDU> writes
>Can anyone tell me where to get information about how much
>energy it takes to raise say one cow, as opposed to how many
>people that same amount of energy could feed? I'm looking for
>vegetarian vs.omnivorian energy efficiency comparisons. Thanks
>in advance for your help.

It depends on how much grass you can eat.

The basic error in concept is to fail to realise that humans cannot
survive on grass (or tree leaves) whilst a cow/sheep can. So a cow/sheep
can exist and feed humans on terrain that cannot be cultivated. Much of
the UK is exactly this sort of terrain.

Now in this modern world it is true that cows and even some sheep are
fed grains that are produced from cultivated areas, however this is mere
economics and not a basic requirement. Were grain to become so expensive
that none were fed to animals then these animals would still be farmed
on areas that could not be cultivated. Unfortunately this level is when
around 80% of your gross income is expended on food. A tough world
indeed, but close to what pertained in the middle ages (and later) in
much of Europe.

So the answer is that it is about as long as a piece of string. From a
highly pampered dairy cow that might need 200kg of nitrogen, one acre
and 2000kg of grain to produce 8000l (14,000 pints) of milk to a
shetland sheep that required no fertiliser, no grain and 4 acres of
rough grazing. Take your pick. One is effectively consuming 5T of grains
worth of resources enough at 1kg/day to feed 15 people for a year but
gives 38 people a pint of milk a day, the other consumes enough
resources to feed no people at all but provides clothing and meat for
one person for oh, maybe a month.

-- 
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.bio.food-science
Subject: Re: Raising cattle
Date: Mon, 17 Feb 1997 06:49:58 +0000

In article <depreej.210.000E449D@lincoln.ac.nz>, "Depree, Jonathan A"
<depreej@lincoln.ac.nz> writes

>Would it be possible to grow wheat, corn etc for human consumption, feed the 
>stalks to stock and thereby raise both cereal and meat from the same plot of 
>land?

Well, the real problem is that fed straw only, cattle will starve to
death. This is a combination of low energy, low throughput due to the
high lignin content and very low protein. Using various semi-industrial
process on the straw, such as strong sodium hydroxide and/or ammonia you
can improve it's digestibility somewhat, but at best growthrates are
very slow. This improves drastically if you feed grains, but you didn't
want to do this. There is good reason why straw is mostly used as
bedding or ploughed under.

One should be cautious of thinking farmers have missed a trick. If they
don't do something obvious, then there is probably a good reason for it.
If something works well, then it is taken up very quickly. What confuses
non-farmers is that 'quickly' often looks slow because it takes a year
before you get ONE shot at it (in most cases). Seasons and soils and
climates differ so a take up over ten years is actually blindingly fast.

-- 
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.bio.food-science
Subject: Re: Raising cattle
Date: Tue, 18 Feb 1997 08:19:36 +0000

In article <depreej.213.0011BA20@lincoln.ac.nz>, "Depree, Jonathan A"
<depreej@lincoln.ac.nz> writes

>Fair enough! I saw an article in one of the recent New Scientists which 
>suggested that it might be possible to alter the lignin content/composition in
>plants and that this might both allow things like corn stalks to be fed to 
>cattle and drastically reduce the amounts of caustic chemicals used in paper 
>making.
>Of course this would involve (shudder) genetic modification.

Actually it wouldn't *need* to involve GM. There is considerable
variation in straw digestibilities (certainly of wheat and barley) at
present. Indeed some barley varieties are grown because the more
digestible straw is deemed worthwhile by the farmer. These varieties
tend to be very prone to lodging (falling over) however. This may (or
may not) be due to microbiological action on the structural celluloses
at the base of the plant since even a small sheath of lignin around the
structural cellulose provides a very significant reduction in
microbiological attack rates. I think (without looking it up) that
cereal straw only contains some 2% lignin, but as a layer surrounding
the cellulose. This has a drastic effect on digestibility.

Actually we DO use quite a lot of straw as feed (mostly to sustain good
rumen function, it's true). All our calves and youngstock are fed straw
and maize by-products in winter until they enter the dairy herd. This is
partly because we are useless at making hay, with a high failure rate
and a huge labour requirement. Straw is much easier and actually a more
reliable product. The animals look and grow well on it although the high
protein and energy of the maize byproduct is mostly the cause, I'm sure.

>Working at Lincoln University I have noticed that the average farmer is fairly
>clued up about what he does.

Highly variable, unfortunately. 

-- 
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"