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

stated that difficulties have been experienced by most breeders in getting mares in
foal until grass is available and this, in Todd's view, is due to the beneficial effects
of vitamins and sunlight in stabilising the endocrine balance. Further Sanders
[1926] showed that a stallion's fertility varies according to the district of the
country in which he stands or travels, being higher in the north and west of
England and Wales than in the south and east and very low in Scotland.

                                                DIET.

There is ample evidence that nutritional deficiencies will modify the sexual
activity of the parent and of the spermatozoa, thus affecting fertility. Paul [1906]
was perhaps the first to show that fertility is affected by diet. Osborne and
Mendel [1919] noticed that although animals fed on artificial diets grew vigorously
to adult size, they were, with few exceptions sterile. Mason [1925] observed that
an increase in breeding capacity is brought about in stalled cattle by turning them
out on to green grass. It is known that lack of vitamins B and E in the diet
results in the degeneration of the germ cells and the seminal epithelium, although
growth and development may proceed in the normal way. With regard to mineral
deficiencies of phosphorus and calcium as a cause of sterility, low fertility and reten-
tion of placenta in cattle, Kelley [1932] refers to the experience of several colonial
and foreign authorities, in particular to Hindmarsh and Hopkirk. The former had
experience of a herd in which cattle were frequently sterile ; oestrum was exhibited
but conception did not take place. During the following year, they were given
a regular ration of bone meal with the result that practically all bred on to time.
Hopkirk has shown that the so-called Waihi Disease which is characterised by the
absence of oestrum is a deficiency condition being amenable to bone meal feeding.
Experimental evidence is available from Germany and elsewhere that sperm pro-
duction is greatly influenced by the feed. A basal ration of 15 pounds of oats and
15 pounds of hay resulted in a sperm production of 2,885,701,420 per ejaculation.
When the basal ration was supplemented by 10 hens' eggs and 5 lbs. of wheat bran
daily, the sperm production was approximately three times as great. A supplement
of dried peas and linseed cake increased the production over that seen with the
basal ration to about 50 per cent. only. Other proteins and lipoid substances
gave results varying between those obtained with the oil cakes and with the eggs.
Further experiments show that rats were inactive sexually when fed on whole
milk until copper and iron were added in small quantities. Deficiency of iodine
also has been proved to act detrimentally on sexual life and fertility. In Australia
potassium iodide is therefore added in small quantities to the ration. Another
agent which has been found useful in the female is wheat germ oil, but no record
of its use in the male has been found. From what has been said above, it will be