The Use of Extremely Low Dietary Calcium to Alter the Production Pattern of Laying Hens

Abstract

The effect of reducing the calcium level of a cage layer diet to 0.09 percent was studied. The commercial egg production-type hens used in these studies had been in production for six or ten months and had received diets containing 3.0 percent calcium. After receiving the low calcium diet for three days, many hens exhibited a paralysis; however, after a pause in production for one day, they were able to stand and function normally. After 14 days on the low calcium diet, production had dropped to 12 percent (experiment 1) and three percent (experiment 2). Upon return to the basal diet containing 3.0 percent calcium, production increased to a level either equal to or higher than the control group within 21 to 28 days. Another group was returned to the basal diet after 42 days on the low calcium diet with resumption in production similar to the 14-day low calcium group.Measurements taken after the low calcium fed birds had returned to control level of production showed interior egg quality and egg shell thickness to be equal to or better than the controls for those birds fed the low calcium feed. No significant differences were found in body weight. Although mortality was higher for birds fed the low calcium dietary treatments in experiment 1, no differences were found in mortality among treatments in experiment 2.One group of hens in experiment 2 was kept on low calcium for 140 days. These birds did not molt and appeared to be in production from outward appearances as did all birds on low calcium diets. Necropsy showed birds on the low calcium diet to have apparently functional ovaries and oviducts; however, the majority were found to be internal layers.