STATISTICAL STUDIES, INDIAN DAIRY CATTLE                 87

         In this data there were 310 cows whose first two lactations were known and the
mean yields for the first and 2nd lactations were 3,767 and 4,067 lbs. respectively, or
putting the 1st lactation yield at 100.0 that for the 2nd came to 108.05. Similarly
there were 263 cows with 2nd and 3rd lactation known giving means of 4,095 and
4,103 lbs. respectively; if the 2nd lactation yield is taken at 108.05, that for 3rd
becomes 108.26 the comparative yields for the 1st, 2nd and 3rd lactations being
100.0, 108.05 and 108.26. The same process was continued for all other ages and
the comparative yields got for different ages are given in Table XIV.

                           TABLE XIV.

         A study of these comparative yields shows that these means increase till 4th
lactation, though the extent of increase between the lactations 3rd and 4th is very
small, and then decrease continuously. These means have not been smoothened in
any way, for it is thought that even these do not represent the true relationship of
the variation of milk yield with age, for in the first section of this paper it was shown
that age is slightly related with both S. P. and D. P. It was not possible to allow
for the 2nd, but the effect of the 1st was eliminated by standardizing all lactation
yields first to 85 days S. P., and from the corrected lactation yields, a composite
curve was built again just in the same way as described above.

         The actual distribution of these corrected lactation yields according to age is
given in Table XV, the means for the different ages being given at the foot of the
same Table.