272             The Nutritive Value of Alkali-treated Cereal Straws

      SECTION II.—The nutritive value of alkali-treated wheat straw

The experiment was so planned that the data yielded would not only
give the nutritive value of the treated straw but would also offer a comparative
picture as regards digestibility and metabolism when the animals were fed
with both untreated and treated straw from the same stack.

The experimental procedure was as follows :—

Four healthy Sahiwal heifers, over three and a half years of age were
selected for experiment. The live-weights of the animals were between 600
and 700 lb. All the animals were started on a ration containing untreated
wheat straw fed ad libitum and weighed quantity of rape cake with an allow-
ance of common salt of 1 oz. per head per day. The ration was fed for 10
days, at the end of which time harnesses were fixed on the animals with a view
to collecting their urine and faeces. The same ration was continued for
another 12 days and during the last 10 days, 24-hourly collections of
urine, faeces and food-residue were made. This period is called ' period 1 '.
At the end of this time the feeding of untreated straw was replaced by that of
treated straw but no other alterations were made in the diet. Following
the same procedure as in period 1, collections of samples were made towards
the end of period 2. The samples collected during the two periods were
subjected to chemical analyses with a view to determining the digestibility
co-efficient and the balance for nitrogen, calcium and phosphorus. Except
during the collection periods, the animals were weighed weekly.

Results

(a) Body weight.—The heifers in the present experiment were compar-
atively advanced in age ; nevertheless, a certain amount of growth was still
evident during the course of the investigation. In Table VIII is shown the
initial body weight (average of the weights taken on the three preceding weeks
before the experiment) and the average body weights in periods 1 and 2. It
is apparent from the data presented that the animals were gaining in weight
at a higher rate during period 2 than during period 1.

                                          TABLE VIII

                    Body weight of the experimental animals