NEW METHODS OF PRODUCING PROTEIN FOR
ANIMAL CONSUMPTION
(Reprinted from The Veterinary Record, Vol. 53, No. 23, 7 June 1941)
D URING war-time the normal supplies of protein imported from overseas
in the form of concentrates such as linseed and cottonseed cake have
become largely cut off. For some years scientists have been at work to find
out possible substitutes. The production of protein at home can be increased
in a number of ways, perhaps the most important being a sound system of
rotational farming and the more extensive use of silage. There are, however,
limits to which such expedients can be extended, and with their fullest use the
vital problem of ensuring an adequate protein supply ultimately for the human
population is not likely to be solved. It is especially in Germany that work has
been carried out to anticipate the current emergency, and the investigations
have been well recorded, so that, if desired, they can be put into application
elsewhere. For example, the technique of fish farming has been well
studied. 1 A fish pond is, acre per acre, a more efficient producer of protein
than is good farmland. When suitably treated sewage is introduced to pro-
vide nutriment for the minute floating animals and plants on which the fish
feed it is even more efficient. Probably the many disused gravel pits in the
home countries could be put to this use.
Seaweed in enormous quantities could be collected from the shallow waters
near our coasts without employing shipping needed for other tasks. There
are some animals—for instance, Orkney sheep—which will eat seaweed. For
most livestock it would be necessary to express and concentrate the juice and
to remove some of the salts.
The employment of certain hormones to increase the fecundity of sheep,
and probably of other animals, has now reached a practical stage, and there is
much evidence available that milk production can be influenced by hormones.
It has now been shown 2 that 50 per cent or more of the dietary protein of
milking cows, growing cattle and sheep can be replaced by certain simple
chemical substances containing nitrogen (' amide ' substances), such as urea,
glycine, ammonium bicarbonate, and ammonium acetate, which are capable
of industrial synthesis. These substances cannot be utilised direct in the
dietary of man, but they are metabolised by the rumenal micro-organizms
which are in turn digested by the animal. The fixation of nitrogen from the
air for the production of explosives played a vital part in the last war. It is
not improbable that fixation of nitrogen for ultimate human consumption
via the animal is destined to play a paramount part in this war. Already in
Germany, dried beet slices, molassed bran, linseed meal, and potato flakes to
which urea has been added, are being produced on a commercial scale.
It is now of prime importance that all possible methods of increasing home
food production should be actively investigated. The last two methods
mentioned above certainly touch in some measure upon the province of the
veterinary profession. They provide a fascinating field for further investiga-
tion. To save shipping space their immediate application becomes a vital
necessity. It needs no repetition that the prevention of animal disease is one
valuable means of increasing protein production. It should not be beyond
our capacities to extend our own activities to the wider fields implied in the
indications to the above scientific discoveries that certainly interest our pro-
fession. [J. E.]
1 See Science in War (Penguin Special), 6d.
2 Nature (1941)147. 531.
76