EFFECTS OF DIFFERENT SHORT-TERM DIETARY PHOSPHORUS LEVELS ON EGG SPECIFIC GRAVITY AND BLOOD PHOSPHORUS OF HENS

In the first 2 experiments, laying hens were fed a direct containing .30% P for a preliminary period of 3 days. At the beginning of the experimental period, hens were fed .30, .75 or 1.40% P with 3.50% Ca. Another group of hens was fed .75% P and 1.40% Ca. Specific gravity of eggs and blood serum Pi were determined and compared with those from control hens continuously fed a diet containing .75% P and 3.50% Ca. Both high P and/or low Ca decreased the specific gravity of eggs and increased the serum P level. In Experiment 2, hens were fed different levels of P at different times of the day. Birds receiving 1.40% P between 0700 and 0930 and 2000 h (Treatment 2) laid eggs with higher specific gravity than hens fed .30% P between 0700 and 0930 h and 1.40% P between 0930 and 2000 h (Treatment 3). There was no further improvement in egg shell quality over that from hens fed .75% P for both time periods (0700 to 2000 h). In both experiments the dietary P level apparently affected egg shell quality.