170
ABSTRACTS
tent 38.5 per cent) prevented their appearance. A 20 per
cent yeast diet even when supplemented with limestone or
calcium carbonate to the extent of 1.8 to 2.5 per cent was
found to be harmful, whereas the addition of cod-liver oil
(declining from 1 per cent to 0.3 per cent) prevented the
occurrence of symptoms.
The main symptoms in the experimental animals were
inappetance, abnormality in gait, appearance of tetanic
spasms and the suppression of urination and defaecation.
The nature of the trouble was considered to be rickets on
the basis of post-mortem findings, and these comprised a
puckering of the articular cartilages of the limb bones (which
could explain abnormal gait), marked thickening of the periar-
ticular connective tissue and abnormal width of the epiphy-
seal cartilages. Histologically, there were fibrosis of the
metaphyseal marrow and some rarefaction of the shaft of
the bone. Throughout the sections, there was observed
an excess of osteoid tissue, both as pure osteoid trabeculae
and as wide margins to the bony trabeculae. Pronounced
osteoporosis was also in evidence.
The paper contains an excellent review of literature deal-
ing with rickets in pigs in general, and in relation to yeast
feeding, a passing reference has been made to ill effects arising
from its use in pigs. In discussing the possible role of yeast
in bringing about the condition, the authors have laid special
emphasis on the high P content of this supplement which
results in a marked shift in the ratio of calcium to available
phosphorus. [P.G. P.]
Storage changes in spray-dried whole egg powder.
L. S. STUART, H. H. HALL and EDNA E. DICKS
(1942). U. S. Egg and Paul. Mag. 48, 629
BACTERIAL and chemical analyses were made of samples of
spray-dried whole egg powder immediately upon receipt from
the driers. They were then stored at 30ºC. at relative humi-
dities varying from 20 to 100 per cent for a period of 60 days,
the analyses repeated, and the changes undergone during
storage studied.
The results of these experiments indicated that spray-
dried whole egg powder which had been properly dried would
not mould if stored at relative humidities of 85 per cent or
less at 30ºC. or below, as well as that bacterial growth would
not occur in stored samples of similar material unless the
relative humidity of the storage atmosphere exceeded 90
per cent at 30ºC. Changes in the solubility of the egg powder
during storage were found to be much more pronounced
when the moisture content of the powder exceeded 5.0 per
cent. Bacteria of the coliform group, if present, tended
to remain viable during storage. Changes in the total bacte-
rial count, as measured by the dilution plate method, were
influenced by the amount of moisture initially present in
the sample. When the moisture concentration was 5 per cent
or less bacterial death appeared to be greater as the moisture
content was reduced. With moisture concentrations greater
than 5.0 per cent, the reverse seemed to be true. i.e. until
it became high enough to allow of bacterial growth. Death
of bacteria in powdered dried egg at moisture concentrations
higher than 5.0 per cent seemed to be associated with the
chemical changes involved in the loss of solubility. It was
observed that marked decreases in the solubility of the stored
material might occur independently of the changes in the
free fat acid content, formol nitrogen value or total free car-
boxyl groups. That pronounced increases in the content of
these latter chemical constituents might be brought about as a
result of bacterial or mould growth during storage at high
relative humidities was also noticed. Changes in the pH
values of stored dried eggs became more pronounced as the
moisture content of the samples increased from 1.94 per
cent to 9.96 per cent. The fact that solubility changes,
decreases in the total bacterial plate count and decreases
in pH values were influenced by the moisture content of the
stored spray-dried whole egg powder indicated that the
most important single factor in the preservation of good
quality during storage may be control of the moisture content
of the product. This would then involve the initial pro.
duction of dried egg powder containing not more than 5
per cent moisture and adequate care in the subsequent storage
and handling processes to prevent moisture absorption.
The above experiments are only of a preliminary nature,
and the conclusions are consequently only tentative. There
is, however, urgent need for more specific information on
such practical points as the most favourable relative humidity
for storage as well as the actual nature of the chemical changes
taking place in stored dried whole egg. [T. S. K.]
Rotenone in low concentration as a tickicide and
insecticide for house pets. ZACARIAS DE JESUS
and ROFINO B. GAPUZ (1940). Philipp. J. Anim,
Industr. 7, 391
IN view of very close association of the dog and the cat
as house pets with the members of the household, tick-
icides and insecticides for these animals should be neither
toxic nor repulsive. They should not be in the form of
emulsions as they will soil the clothes and furniture. A
mixture of rotenone and cassava starch in concentration of
one and two per cent rotenone was found effective as a tick-
icide for dogs. Twenty to 50 grams of the preparation were
necessary to treat one dog. Rhipicephalus sanguineus and
Dermacentor sp. were killed in from 24 to 72 hours and these
ticks remained attached to the skin of the host until they
died and dried up. The mixture has been reported by
the authors to have great insecticidal values against cat
and dog fleas. The fleas die soon after the application,
When applied liberally all over the body, head and appen-
dages of the infested dogs and cats, one application was
found sufficient to effect complete destruction of the ticks
and fleas. In the case of gravid ticks, it was found necessary
to repeat the treatment the following day or on the third
day due to the high resistance of the ticks to the tickicide
at this stage. Trials made on guinea-pigs had shown that
the mixture was also effective against lice, killing them in
a short time. To prevent the rotenone from deteriorating,
the mixture should be kept in a well-stoppered bottle and
should not be exposed to direct sunlight. [B. C. B.]
Feeding urea to dairy cows. J. G. ARCHIBLAD
(1943). Massachusetts
Experiment Station
Bulletin 406, 16
IN three years' trials with dairy cows with double reversal
and continuous rations, it was found possible to replace as
much as 42 per cent of the total N in the grain and 25 per
cent of the total N in the entire ration by urea. In making
the substitutions, urea replaced standard protein concen-
trates such as cottonseed meal, soybean meal and corn
gluten feed. Urea gave some favourable results, but it was
not quite on a par with the standard protein concentrates
for maintenance of milk production.
Some factors influencing reproductive efficiency
of range cattle under artificial and natural breed-
ing conditions. J. F. LASLEY and R. BOGART
(1943). Missouri Station Research Bulletin
376, 56
ARTIFICIAL insemination proved a practical and efficient
method for breeding nearly 2,000 range cows over a period
of three years. Of the cows inseminated one or more times,
78.8 per cent produced calves and required an average 0