The effect of feeding magnesium-enriched diets on the quality of the albumen of stored eggs.

1. Pullets were given from 1-d-old diets containing 1-6, 4-1, 8-1 and 12-0 g Mg/kg. Only small effects of these diets on live weight, food consumption, egg number, egg weights or egg-shell thickness were observed except at the highest level (12-0 Mg/kg) which caused diarrhoea and an appreciable lowering of the live weight of growing pullets. A further group was given from point-of-lay a diet containing 9-3 g Mg/kg. 2. Eggs laid on 3 consecutive days from each of eighteen hens were collected at intervals of 3 weeks until the birds were 68-5 weeks old. Eggs laid on the 3rd day were used to determine the initial proportion of thick egg-white present and also the concentration of Mg, Ca, Na and K in the thick egg-white. Eggs laid on the 1st and 2nd days were stored at 20 degrees for 20 d to establish the proportion of thick egg-white remaining after storage. 3. With the unsupplemented diet the proportion of residual thick egg-white after storage of eggs for 20 d at 20 degrees was 306, 161 and 305 mg/g total egg-white when the hens were 26-5, 53-5 and 68-5 weeks of age respectively. When the diet containing 9-3 g Mg/kg was given, the proportion of thick egg-white after storage remained approximately 400 mg/g throughout the period of the trial. 4. The mean Mg concentration in the thick egg-white of eggs laid by hens given unsupplemented diets was 5-77 mM. The addition of extra Mg to the diet increased the content of Mg in the thick egg-white, for example when the diet contained 9-3 g Mg/kg the mean concentration rose to 7-69 mM.