ABSTRACTS
95
eriarnce as a factor in poultry disease research.
C.A. BRANDLY and N. F. WATEAS (1942).
Amer. J. vet. Res 105-110
FEN'S work on resistance to mycotic stem rust in
eat demonstrated the importance of inheritance in
ation to diseases and laid the foundation of the present
knowledge of disease heredity. Progress with
mals due to practical difficulties has, however, been
ch slower than in plants. Numerous examples are
en of the inheritance of non-infectious pathological
ditions in animals and birds. Reference is also made
the work of various workers upon differences in
ceptibility among families within species or varieties.
the role of hereditary resistance and susceptibility of
various classes of animals to various neoplasms and
cemia has been definitely established by numerous
rkers. The possibility that a pathogenic organism
virus may change or mutate must also be borne in
id.
Stress is laid on the necessity of working on host
terial of known resistance or susceptibility. However,
vironment is also very important for the level of
istance which is inherited can be altered by feeding
management.
Though the fundamental principles of genetics are
atively simple, it is unfortunate that most of the
nomic characters in both plants and animals are
dependant on the interaction between many genes and
t on two genes as in some of the lower forms of life.
breeding automatically brings about homozygosity
that the same time it increases the diversity from
nily to family even though these families start
m common stock; Inbreeding increases homozygosity
both good and bad characters but it does not create
fects and it merely uncovers them by purification of
characters
already present. Inbred strains of
all animals have proved of great value in research
t little systematic inbreeding has been done in large
imals.
Little information is yet available about the mech-
ism of inherited immunity. In pullorum disease it
s been shown that the lymphocytes are present in
eater numbers and percentages in resistant chicks from
e 18th day of incubation to the 3rd day after hatching.
Further resistance increases rapidly with age due to
crease in the lymphocytes. Age resistance in chickens
Ascaridia lineata is due to an increase in goblet cells
the duodenal mucosa and the mucus secreted by these
lls inhibits the development of the parasite.
Chickens and other species of poultry are very
itable for genetical studies in relation to diseases,
r they can be kept fairly cheaply and large numbers
n be bred rapidly. By exposure of unselected stock
standard infection, it is sometimes possible, even
one generation, to classify into resistant and
seeptible groups.
In using the term resistance or immunity and
seeptibility, it is important to remember that all of
e individuals of any particular strain may not behave
ike; some of the so-called resistant strain may contract
e disease whilst others of the susceptible strain may
t succumb. Statistical examination of all the data
,therefore, essential. Frequent testing of the host
aterial is also essential if the degree of immunity is to be
aintained or increased. [A. J. M.]
What research has accomplished in modern poul-
try production. E. JUNGHERR (1941). Amer. J.
vet. Res. 2,259-61
THE author discusses the influence of research in
building up the poultry industry and singles out four
branches of poultry science, namely management, gene-
tics, nutrition and pathology. The author does not
give a critical review but merely cites various examples
which have had much influence on the development of
the industry.
Mass. production of poultry has been rendered possi-
ble only through the introduction of artificial incubation,
and amention is made of the pioneer work done by W. P.
Hall and S. B. Smith. Research on house construction,
ventilation and range management has also contributed
to the growth of commercial poultry farming.
The remarkable achievement of a hen which laid
1,464 eggs in eight years at the Vineland contest is
quoted as an example of what has been done through
intelligent breeding based on critical research. The
work of Raymond Pearl, who carried out the first
systematic analysis on fecundity, along with the resear-
ches of Goodale and Hays on the factors governing egg
production, is mentioned. Acknowledgments are made
to work on progeny testing by Gowell and on sex linkage
by Dunn, but no mention is made of the fundamental
researches on sex-linkage by Punett and Pease.
In the field of nutrition, the work on poultry takes
only second place to that on rats. Mention is made of
the pioneer work by Eijkman who used poultry to
investigate the anti-beri beri vitamin. Other contributions
mentioned are the discovery of vitamin D by Mc Collum
and Simmonds, the value of cod liver oil in preventing
rickets in chickens by Hart Haplin and Steenbock and
the value of manganese in preventing perosis by Wilgus,
Norris and Heuser.
In the realms of pathology, mention is made of the
discovery of bacillary white diarrhoea by Rittger and
the method of vaccination against laryngotracheitis
introduced by Beauditte and Hudson.
The value of poultry meat and eggs in human
nutrition is also touched upon. The discovery of
vitamin K, the blood coagulating factor, in chicks and
its present use in combating haemorrhage in man has
proved of great value. The work of Rous and
Goodpasture on chick embryos has proved of immense
value in the production of human and animal vaccines.
Despite the advances that have been made, adult
mortality has steadily increased during the last twenty
years, both in America and Britain. Work on a large
scale on the dreaded fowl paralysis or leucosis complex
is now being carried out at the U. S. Regional Poultry
Research Laboratories, East Linsing, Mich. The author
calls for closer cooperation among all branches of
research workers in order to meet the many problems
still confronting the industry. [A. J. M.]
Co-ordinated trials with phenothiazine against
nematodes in lambs. (Imperial Agricultural
Bureaux Joint Publication 4,1943)
Conflicting reports on phenothiazine as an anthelmi-
ntic and the use of different criteria in the assessment
of its efficacy led the Agricultural Research Council of
the United Kingdom to plan and institute a series of
co-ordinated trials at several centres in Great Britain
to accumulate results that would admit of adequate
statistical analysis, and would also furnish answers
to certain specific questions. The present report is the
outcome of findings at different centres.