REVIEW
Animal Breeding in the Light of Genetics—Seventh International Genetical
Congress (Section D). Imperial Bureau of Animal Breeding and
Genetics (Oliver and Boyd, Edinburgh, 1939). Price 3s.
T HIS publication is a lucid résumé, of the major features discussed at the
Congress and the record is divided into nine parts or meetings. The trend
of discussion stresses that the development of genetics would help the livestock
breeder to make more desirable combinations of characters in his animals.
McPhee of the United States described the attempts to co-ordinate research
on farm animals in that country. He stressed the necessity of considering
more than one character at a time; and mentioned the close association
between the degrees of improvement in different forms of livestock and the
ease with which their productive characters can be measured—characters,
such as milk production, which can be measured can be more easily improved
than those not on a measurable basis, such as beef and draft qualities.
Bonnier of Sweden discussed the theoretical and practical contributions
of genetics to the improvement of livestock. He rightly emphasised the fact
that improvement depends upon selection, but that selection can only be
effective when observed differences are genotypic. He added that such
methods as panmixis and polyploidism, used by plant breeders, might be of
some value in animal improvement. Hagedoorn of Holland outlined what
he called the ' nucleus plan' of animal breeding in which males are judged
according to the quality of their progeny. Really important qualities are
given preference over show qualities whose values are still speculative. Only
breeding males that are sons or grandsons of such ' nucleus sires' should be
used, according to this author.
Bisschop of South Africa reported on data on the macro-morphological,
the micro-morphological and environmental conditions of indigenous and
exogenous cattle in the semi-arid regions of his country. Rhoad of the United
States outlined a method of assaying genetic differences in the adaptability of
cattle in tropical and subtropical climates. The method consisted of measure-
ments of the relative efficiency of water expenditure and of heat disposal
between different genetic types of cattle ; this is used as an index to assess the
degree of physiological adaptability to temperatures and intense solar radia-
tion. Rhoad concluded that such differences were genetic. Manresa et al.
of the Philippines reported on the influence of atmospheric temperature on.
the haemoglobin and other blood constituents of cattle.
In respect of artificial insemination, it was observed that two major
problems are involved in livestock improvement; the selection of a good sire
and the maximum utilization of such an animal. Artificial insemination has
greatly enhanced the latter. Organizations responsible for campaigns for
such work in Italy, Poland, Rumania, Kenya and the United States were
discussed, together with methods of collection, storage and transportation of
the semen.
The value of measurement which would be capable of sound interpretation
is greater than many breeders realise. In this respect very few papers were
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