The Ability of Hens to Regulate Protein Intake When Offered A Choice of Diets Containing Different Levels of Protein

Two experiments were conducted to determine that ability and extent of self-regulation of protein intake by the laying hen. In the first experiment, hens were offered a choice of two diets in the following combinations: 8% vs. 11% protein, 8% vs. 14% protein, 16% vs. 16% protein and 16% vs. 23% protein. In the second experiment, the first two treatment groups of the first experiment were replaced by 8% vs. 16% protein and 12% vs. 16% protein, respectively. The other two groups remained the same. Percentage of diet choice, body weight changes, egg weight, egg specific gravity and serum calcium were determined for both experiments. Individual hen feed consumption over a twelve hour period was measured at two hour intervals for two days at the end of both experiments, which lasted approximately one month each. Hens in the 8% vs. 11% protein group, the 8% vs. 14% protein group and the 8% vs. 16% protein group showed significant increases in their consumption of the diet higher in protein. The highest preferential consumption occurred with hens in the 8% vs. 14% protein group, which also lost the most body weight. In the first experiment, egg production, egg weight and serum calcium increased as the protein content of the diet increased until the average protein content of the diet was 16%. In the second experiment, the differences in egg production, change in body weight, serum calcium, egg weight and egg specific gravity between groups were greatly reduced. Weighing feed at two-hour intervals in the second experiment revealed a drop in preferential consumption of the 16% protein diet in the 8% vs. 16% protein diet group during the course of the day. Total protein consumption, however, peaked in the early afternoon.