200 INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, II

that prolonged feeding of calcium and phosphorus cured or prevented the infection.
Folmer Nielsen (20) points out that the importance of contagious abortion
depends, chiefly, on its chronicity. If this, as Smith suggests, is due, not to
Br. abortus, but to other organisms it might be thought that, following the first
abortion, the condition should be regarded in the same way as other infections.

There appears to be good ground for the view that diet affects susceptibility
to infection. Williams (21, 87) points out that bacteriological studies show
that the organs of the non-pregnant cow contain many bacteria which are usually
harmless, but assume a pathogenic role under unfavourable influences. Such
unfavourable influences, he suggests, are to be found in improper feeding. Nielsen
(20) shows that the incidence of uterine infections and of the associated ovarian
changes increases with number of gestations and lactations, and Quinlan (24)
emphasises the importance, in the treatment of all such cases, of attention to
diet. These suggestions are in complete agreement with what is known of
susceptibility to infections of other areas (22). Deficiency of vitamin A alters
the condition of the mucous membrances of the respiratory passages, and the
defence mechanisms of the body, so that organisms which normally exist in the
body without causing signs of disease become pathogenic. A rickets-producing
diet, fed to rats which are normally immune to tuberculosis, cause them to become
highly susceptible. Hence there is an increasing tendency to believe that these
infections of the genital tract may be, to some extent at least, the result of poor
condition and improper feeding. Stalfors (23) considers that catarrhal conditions
of the uterus may depend on lack of tone in the uterine muscle, and that the
effect of iodine irrigation, as frequently practised, may be due to the stimulant
action rather than to any antiseptic property of the solution used. An excellent
review of this question is given by Quinlan (24), who is also of opinion that the
adequacy of diet has not received sufficient attention.

Ovarian changes.—Again, although it cannot be denied that ovarian changes
may arise in consequence of infection of other parts of the genital system,
there is abundant evidence that such changes may be the direct result of faulty
nutrition. Presumptive evidence is afforded by the conditions under which ovarian
disease usually occurs. According to Hess (13), cystic degeneration of the
ovaries occurs most frequently in early maturing, high-milking breeds, and
it occurs at an earlier age where breeding and milk production are intensive.
Although actual statistical data do not appear to exist, this seems to be the
consensus of opinion. It implies that the nutritional demands for early maturity,
frequent breeding and sustained high-milk production are not fully met. Conklin
(25) definitely attributes to this cause the sterility following record-breaking