ABSTRACTS
87
The amino acid deficiencies of certain plant proteins and the supplementary
effect between plant proteins as measured by means of their
biological values. J. S. C. MARAIS and D. B. SMUTS
(1940). Onderstepoort J. 15, 225
I N a previous work, the authors proved the deficient nature of various plant proteins by
the growth response obtained by the paired feeding method in rats. This paper deals
with the determination of the biological values of different plant proteins as well as the
values obtained by the supplementation of such feeds with various natural as well as
synthetic food-stuffs and chemicals. Such values will be of help not only to study, in
detail, the changes in the nitrogen balance but also to apply the information in the
economical nutrition of farm animals. Thus, it may be known that lucerne is deficient
in cystine, but unless the nitrogen conservation through the addition of cystine or other
plant proteins is known, the results remain of purely academic value.
The biological values of different seeds were obtained by using rats as experimental
animals. Special cages and food pots used in the experiment are described.
The
biological values for lucerne meal + 0.2 per cent d-methionine, whole oats seed +
0.2 per cent d-lysinedi-hydrochloride, pea nut meal +0.2 per cent l cystine, pea nut
meal + 0.2 per cent d-methionine, linseed meal + 0.2 per cent l cystine, whole yellow
maize meal + lucerne meal and whole yellow maize meal +soya-bean meal are 90, 86,
66, 78, 86, 80 and 75 respectively. From previous experiments the biological values for
lucerne meal, pea nut meal, linseed meal, whole oats seed, whole yellow maize meal and
soya-bean meal are known to be 60, 72, 78, 83, 67 and 55. The supplementation of lucerne
with methionine, therefore, improves the nitrogen utilization of the lucerne proteins by
30 per cent. On the other hand, the supplementation of oats seeds with lysine or pea
nut meal with cystine shows little or no improvement at all, thus proving that the proteins
of these feeds are not deficient in the respective amino acids. The increased biological
values of pea nut meal and linseed meal on the addition of methionine and cystine
demonstrate the deficiencies of the proteins of these feeds in these amino acids.
If no supplementary relationship existed between the proteins of yellow maize and
lucerne, and yellow maize and soya-bean, the mean biological values of the protein
mixtures would have been 64 and 61 respectively. The much higher values obtained show
on the other hand that the lysine and tryptophane deficiencies of yellow maize are made
good by lucerne and soya-beans; whereas the cystine deficiency of the proteins of
lucerne and soya-beans are corrected by the addition of maize meal. Thus though
the protein of individual food stuffs may be of low nutritive value, the mixture of two
such deficient feeds may have highly improved biological efficiency. [S. N. R.]
Studies on control of liver fluke of cattle in the Hawaiian Islands. E.
ALICATA JOSEPH (1941). Amer. J. Vet. Res. 2, 152-66
A T the outset the author has considered the factors involved in the maintenance and
spread of fascioliasis in the Hawaiian Islands. These consist of the swampy condi-
tion of the country, the poorly drained lowlands, the mild climate which offers an ideal
environment for the propagation of snails and for the hatching of the fluke eggs, and the
feeding of cattle on cut forage from swampy areas and allowing them to graze on such
lands.
The methöds of fluke control are considered under three heads, viz. (1) the control
of the fresh-water snail which serves as an intermediate host; (2) protection of animals
from infection and (3) destruction of flukes of cattle by the use of anthelmintics.
(1) Snail Control. The author recommends the solution of 1 part of copper sulphate
in 300,000 parts of water for the destruction of snails. In regard to the biological control
the author found that, although the crayfish (Astacus nigrescenes) is a very good snail
predator, it burrows holes in the banks and occasionally destroys the taro corms. It
was, therefore, considered unwise to release the crayfish in the swamps. The author ad-
vocates fireflies (Luciola spp.) as a possible biological means of controlling the snails.
The larvæ of these flies are carnivorous and utilize fresh-water snails as food.