Sources used in this calculation method are:
Luo, J., A. L. Goetsch, I. V. Nsahlai, J. E. Moore, M. L. Galyean, Z. B. Johnson, T. Sahlu, C. L. Ferrell, C. L., and F. N. Owens. 2004. Prediction of voluntary feed intake by lactating, Angora, growing and mature goats. Small Rum. Res. 53:357-378.
Sahlu, T., A. L. Goetsch, J. Luo, I. V. Nsahlai, J. E. Moore, M. L. Galyean, F. N. Owens, C. L. Ferrell, and Z. B. Johnson. 2004. Energy and protein requirements of goats: developed equations, other considerations, and future research to improve them. Small Rum. Res. 53:191-220.