38      THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, I.

                         RESULTS : BUFFALOES' WEEKLY YIELDS.
The data for buffaloes were first made use of for testing if the equation accu-
rately represents them. There were 140 lactations obtained for buffaloes from the
records of the Northern Circle. The average weekly yield of each week of lactation
was worked out. These are represented by the dotted line in Figure I. It will be
seen that the yield rises up to the 5th week, remains steady till the seventh and
declines from the 8th. The equation was applied to the decline portion of the curve,

             FIG. I.—Lactation curve for buffaloes—weekly yields.

             [NLS note: a graphic appears here - see image of page]

that is, to the data of yields from the 8th week of lactation, and the values of
the constants, maximum and rate of decline were determined. The method of
determining these is by what is known as method of least squares,* the virtue of
which is that the error is the least possible. The smooth curve obtained from the
calculated data is represented by the continuous line in Figure I. From this it will
be seen that the average buffalo starts with a maximum of 142.5 lb. per week in the
7th week of lactation and then declines weekly at the rate of .0265 lb. per lb.
per week (which is about 2.65 per cent.). The observed and calculated values of the
weekly yields are given in Table I. Column 5 of this Table shows by how much the

                            * The method of calculation is explained in Appendix I.