Calcification on 1% of controlled cod-liver oil was less satisfactory than on 1% of genuine cod-liver oil as judged by radiography at 5 weeks old. Growth rates were not significantly different.

⅔ of 1% of the genuine cod-liver oil promoted calcification as satisfactorily as (and significantly better on one diet than) 1% of controlled oil. The mean tarso-metatarsal distances on ⅔ of 1% of controlled oil were too wide for the calcification to be regarded as normal. It has thus been shown that satisfactory growth is no criteria of adequate calcification and bone structure.

From the age of 6—16 weeks, ⅔ of 1% of controlled cod-liver oil mixture was not adequate, as demonstrated by radiographic examination, for optimal calcification; but using the criteria of naked eye examination and weight, no significant difference would have been found between genuine cod-liver oil and the controlled mixture. These birds showing subnormal calcification could not be expected to stand up well to the strain of laying, which puts heavy demands upon the calcium metabolism.