202
ABSTRACTS
in the host have had very encouraging results in man,
horses and dogs ; much less so in ruminants. The applica-
tion of mass treatments of man and animals is not, how-
ever without its disadvantages : financial as well as
administrative and consequently comparatively little
has been done. There remains, therefore the treatment
of fæcal material before it is used as manure. This
may be physical, chemical or both. The physical treat-
ment involves natural or artificial heat as a killing agent.
Natural heat may be generated in a well-packed manure
pile or in an insulated manure box. Artificial heat
involves a specially constructed manure box.
Comparatively little has been done to find chemical
methods of destroying the free-living stages of the nema-
todes. It is a problem which presents many difficulties
probably the greatest of which is the fact that the eggs-
and larvæ are always in close contact with fæces, soil or
grass, and many chemicals which might be used are par-
tially or completely counteracted by contact with organic
matter. Nevertheless chemical control of all free-living
stages does appear to have considerable practical possibi-
lities. It offers opportunity of using fæcal material
as manure and even of enriching the manurial value and
it does not necessitate special equipment.
The joint authors record their experience with ninety-
eight chemicals while dealing with Selerostomes of horses.
1. Some chemicals such as flowers of sulphur destroy
only the fungi without affecting the eggs or the larva
of worms.
2. Some chemicals, such as ferrous sulphide, ferric
oxide, ground limestone, rock phosphate, basic slage,
derris, white helledore, and pyrethrum powders are
inert.
3. Some chlorides and sulphates, sodium and potassium
hydroxide and potassium permanganate occasionally
cause exsheathment. These chemicals, in slightly greater
proportions, generally also cause the death of the larvæ.
4. A large number of chemicals mixed with fæces in
certain proportions allow a considerable number of eggs
to hatch and the larvæ to reach the infective stage and
then compratively rapidly kill the larvæ. Such chemicals
are quicklime, cupric, ferric and ferrous sulphates, zinc
sulphate and zinc sulphide, the chlorides of copper, iron
and zinc, cuprie nitrate, sodium fluosilicate and oxy-
quinoline sulphate. Other chemicals which cause de-
layed death are nicotine sulphate, trisodium phosphate,
sulphate and chloride of manganese, sodium and mag-
nesium borate strong cresol, phenol and calcium hypo-
chloride
5. Larvae having thick sheath and the egg in the centre
if the lump of fæces may be protected from the action of
chemicals.
6. Applied dry, chemicals which are deliquescent have
more prospect of being of practical value, for the moisture
which they attract may also attract the larvæ. With
very lethal chemicals, such as iodine salts, it has been
found that very considerably less chemical is necessary
to produce sterilization with a very weak rather than
with a very strong solution.
Some chemicals such as chloropicrin, calcium cyanide,
naphthalene, O' and para' dichlorobenzene can be used
as gases.
The cost of the chemical has also to be taken into
account. Urine has more or less all the advantages.
Another class of chemicals are the artificial fertilizers.
Aniline and pyridine are lethal both to fly larvæ and
sclerotome larvæ. The advuntage of such a dual steri-
lizer is obvious from the economic point of view.
At the end of the article is given a list of chemicals
used, with the percentage necessary to cause sterlization
and the strength of the solution to be used. [G. D. B.]
Studies on the chemical composition of the blood
of dairy cattle III. The normal concentration
of Inorganic Phosphorus in the whole blood of
dairy cattle and factors affecting it. LANDINGHAM,
H. O. HENDERSON, and G. A. BOWLING (1942).
J. Dairy Sci., 25, 529.
THE authors have studied the normal values of the
concentration of inorganic phosphorus in more than 000
samples of whole blood taken from 59 dairy cattle—
cows and heifers, during the periods of growth, gestation,
and lactation at different seasons of the year and with
and without exposure to sunlight. The Fiske and Sub-
barow method for inorganic phosphorus was followed for
analysis.
They observed no indication of any difference in the
inorganic phosphorus content of the blood as a result of
the ration supplying liberal quantities of phosphorus.
In the case of growing heifers calves, ago was found
to be the most important factor affecting the concentra-
tion of inorganic phosphorus in the blood; which showed
an increase with age up to about the sixth or seventh
month and then a gradual decline as the animals grew
older. The maximum value, 7.15 mg. per 100 ml.
whole blood, was recorded during the seventh month.
With lactating cows, a decrease in the blood inorganic
phosphorus, was noted with an increase in the number of
lactations up to about the third or fourth lactations.
During the period of first gestation a lower concentration
of inorganic phosphorus (481 mg. per 100 ml. whole
bloed) was observed in the blood of heifers than in that
(5.68 mg. per 100 ml. whole blood) of non-pregnant
heifers of the same age. The inorganic phosphorus value
showed practically no change throughout the first lacta-
tion period, but dropped readily rear the end of the second
gestation period and during the first three months of the
lactation, thereafter the value increased to same level
as during the first lactation. The value showed again
decrease in the latter part of the third gestation period
and for the first two or three months of the third lactation.
After the third lactation no significant change in blood
composition was observed.
The data obtained for growing heifers from the age of
one month to the time of first calving did not indicate
any seasonal effect upon the inorganic phosphorus con-
tent of the blood. The fact that the animals were con-
fined to the barn continuously or permitted to run outside
in favourable weather, also made no difference. How-
ever, there was a strong tendency for dairy cows after
the first lactation to show a lower concentration of in-
organic phosphorus in the blood during the winter and
early spring than during the summer and early fall.
[S. A. M.]
Vitamin A deficiencies in ruminants. H. SCHMIDT.
(1942). Amer. J. vet. Res., 2, 373
THE author studied the effect of the Vitamin A defi-
ciency in food on cattle, sheep and goat. He described
the symptoms, depletion period and the effect of supple-
menting the feed with the sources of Vitamin A and caro-
tene. The minimum requirement of this constituent in
cattle, sheep and goat for maintenance was also worked
out.
One group of cattle was fed on a vitamin A deficient
ration consisting of cotton-seod meal, cotton-seed hulls
and white grain. The control group received alfalfa
hay in addition to the deficient diet. After 120 days on
this feed the experimental animals stopped growing and
started to lose weight. They also showed night-blindness,