76      Factors affecting Physical & Chemical Constants of Ghee

those of butterfat from the feeding of cod iver oil. They also observed that
the analytical values varied markedly in the direction indicating a consider-
able passage of the oil or some of its constituents into milk fat. Hilditch
and Thompson [1936] conclusively showed that the change in composition
of milk fat on feeding cod liver, linseed and other oils in addition to normal
rations consists in an increase in unsaturated acids together with a decrease
in butyric and stearic acids content. In this experiment the increase or
decrease in the lower saturated fatty acids (Reichert value) and unsaturated
acids (iodine value) obtained by feeding oil cakes showed a marked relation
to the composition of the fat fed. This, and the findings of other workers,
explain the characteristic values obtained in the case of coconut cake.
Hilditch and Sleightholme [1930, 1931] have shown that when liberal amounts
of coconut cake were fed to cows, the butterfat showed a rise in saturated
acids (myristic and a minor rise in lauric) but for the most part, the composi-
tion of the unsaturated glycerides was normal. The results obtained in this
experiment, while showing no appreciable change in Reichert value and rise
in Polenske value showed a definite fall in iodine value. In their experiment,
Hilditch and Sleightholme fed coconut cake in addition to a normal ration
while in this case coconut cake formed the main part of the concentrates in
the ration. It is possible, therefore, that the effect of coconut cake in their
case was counteracted by other components of the balanced ration. Siegfeld
[1907] observed similar effects with coconut cake feeding. He found that
feeding coconut cake up to 4 lb. per head per day increased the Polenske value
from 2.5 to 3.8 whilst the Reichert value was not appreciably changed.
Cranfield [1911] also reported similar results and concluded that coconut cake
produced a better quality butter than linseed or cotton cakes.

The body, texture, colour, and flavour of butter and ghee depend largely
on the nature of the food of the animal. As a general rule, foods which cause
an increase in oleic acid content of butterfat produce a fat of low melting
point and those which cause an increase in palmitic and stearic acid produce
a fat of firm consistency and high melting point. The oleic acid content
of butterfat increases with the progress of lactation, age of the animal and
also when animals are fed on green grass [Dean and Hilditch, 1933 ; Brouwer,
1931]. The results obtained show that the feeding of gingili and groundnut
cake produces a butter and ghee of unsatisfactory body and of oily texture.
In feeding coconut and linseed cake, the quality of butter improves to a great
extent but that of ghee deteriorates due to an oily flavour. Cotton seed is
an exception as compared with other oil cakes, since an increase in the per-
centage of oleic acid is counteracted by the decrease in percentage of butyric
acid. Also, the adverse effect of cotton seed feeding can be counteracted by
including green grass in the ration [Neasham and Gelpi, 1934]. This explains
the better results obtained by feeding cotton seed meal in this experiment.

Corn silage, oats, molasses and beets are known to increase the butyric
acid content of milk fat [Hunziker, Mills and Spitzer, 1912 ; Platon et al.,
1935]. Our results also indicate a rise in the Reichert value of butter fat
of animals kept on green grass and cereal diet without oil cakes.

In both these cases, a few days feeding produced its effect on the butter-
fat and the milk yield of animals. The milk yield in all cases fell considerably.