

e 
A STUDY OF RATIONS FED TO MILCH COWS. 13 
_ were between four and twelve, and three were over twelve years 
old. One hundred and sixty of the 196 animals which were four 
years old or older, were in the period of lactation (from flush to 
eight months past calving) during which the largest yields of 
milk and butter-fat are expected. 
Tables 14 to 29 inclusive contain the results, in considerable 
detail, of the studies of the sixteen different herds. They are all 
alike in arrangement, and a description of one will serve for all. 
Each table contains the condensed results for a herd. Table ra, 
for instance, gives statistics for herd No. 1. 
The first (upper) part of the table gives a reference number of 
each animal, its breed, age, weight and number of months since 
last calf. The smallest daily milk flow, the greatest daily milk 
flow and the total yield of milk for the five days are given in the 
next three columns. In the three following columns are given 
the lowest, highest and average percentages of fat found in the 
daily milk of each cow for the period of five days. ‘The figures 
were obtained by adding together the five daily determinations 
and taking the average, hence this actual average is not always 
half way between the highest and lowest. The yield of fat is 
given in the last three columns of the first or upper part of the 
table. The minimum and maximum yields of fats were obtained 
by multiplying each day’s milk by its percentage of fat; the low- 
est number thus obtained gives the minimum daily yield of fat, 
and the largest the maximum yield of fat. It is to be noted that 
these numbers are not the same as would have been obtained by 
multiplying the minimum and maximum daily milk flow by the 
minimum and maximum percentages of fat. The total yield of 
fat for the five days was found by taking the sum of the daily 
yields of butter-fat. 
The second, or lower part of each table, gives the kinds and 
amounts of the different food materials eaten per day per 2,000 
pounds live weight, and the weights of the total and digestible 
nutrients (protein, fats and carbohydrates) which they furnished. 
As stated previously, all of the different feeding stuffs used in 
these rations were analyzed, and from the results of these an- 
alyses the weights of the total nutrients furnished by the different 
coarse fodders and concentrated foods were obtained. The 
results of these analyses are given on pages 17-27 of this Report. 
The method employed in calculating the fuel value or potential 
