STUDIES ON THE DETERMINATION OF DIGESTIBILITY COEFFICIENTS:         99

3. The minimum number of tests necessary for a desired standard of accuracy

has been derived from the formulae E²= σ²/ n where

                   σ=% standard deviation found
                   E=% standard deviation aimed
                   n=number of replications.

4. The limited number of requisite data did not permit of a more extensive
trial of the formulae, and even here it has been confined to a test on two feeds
as no data with three feeds were available. The results have, however, been highly
encouraging and it is found that, with respect to paddy straw and cake (two feeds),
a fair order of accuracy is possible with a replication of 3 to 5, except in the case
of crude protein and ether extract under paddy straw and crude fibre under linseed
cake.

5. The method of computation enables us to set a direct evaluation of indivi-
dual digestibilities and thus obviates the necessity of conducting separate trials
with single feeds followed by combined feeds.

                                ACKNOWLEDGMENTS

The first acknowledgment is due to the Imperial Council of Agricultural
Research for providing the grant for the work.

The authors are indebted to Mr. K. McLean, Director of Agriculture, Bengal,
for encouragement, to Mr. F. J. Gossip, Livestock Expert, Bengal, for stall
facilities and practical help, to Mr. G. B. Pal, Officiating Agricultural Chemist for
helpful criticism.

The authors also beg to acknowledge their indebtedness to Mr. Abdul Hye,
Assistant Chemist, for many suggestions and help and to Mr. Syed Ali for the
major part of the computation.

Finally, the authors acknowledge with pleasure the ungrudging help and
suggestions received on the statistical side from Prof. P. C. Mahalanobis and
his colleague, Mr. S. Bose of the Indian Statistical Institute, Calcutta.

                                   REFERENCES

Armsby, H. P. (1930). The Nutrition of Farm Animals.

—(1910). The Principles of Animal Nutrition.

Carbery, M., Chatterji, I. and Hye, A. (1934). A New Method of Experimentation
     and Computation for Directly Obtaining he Digestibility Coefficients of Indivi-
     dual Feed Nutrients in a Mixed Ration. Ind. Jour. Vet. Sci. and Ani. Husb.,
     44, 295.340.

Fisher, R. A. (1925). Statistical Methods for Research Workers.

Woodman, H. E. and Stewart, J. (1932). Jour. Agri. Sci. 22, 3, 527-547.