The Use of High Magnesium Limestone in the Diet of the Laying Hen

INTRODUCTION DOLOMITIC limestone, though abundant in many areas of the United States, has not been recommended for use as a calcium supplement in the rations of laying hens since early reports (Hart et al. 1923; Kennard, 1925; and Halpin and Hayes, 1925) indicated that it produced detrimental effects. The agreement between these different reports was excellent. Dolomitic limestone contains about 20.5% calcium and 12% magnesium. All workers listed above found that dolomitic limestone, which has a high magnesium content, tended to decrease egg production in comparison to the oyster shell type supplement. Alder (1927) emphasized that dolomite seemed to not only decrease egg production, but also resulted in a progressive decrease over time of shell thickness. He also found that pullets receiving dolomite became extremely nervous, were easily frightened, and that the birds developed diarrhea. Tully and Franke (1934) in a series of trials lasting five years found no difference…