Effect of Dietary protein and Added Fat Levels on Performance of Young Laying Hens

A 20-wk experiment was conducted to evaluate the effects of dietary protein level and addition of fat to a 20% protein diet on performance of young laying hens. The six dietary treatments consisted of corn-soybean meal diets containing 20% CP plus 0, 2, 4, or 6% corn oil or 18 or 16% CP with no added fat. The corn oil was added in place of corn and soybean meal; therefore, ME_n increased as added fat increased. The diets were fed to hens from 20 to 40 wk of age. Body weight of hens fed the 16% CP diet was less Pthan that of hens fed the other diets. Egg production was not consistently affected by added fat or protein level. Added fat increased egg weight, egg size (% large and above) and egg mass output, with the largest response occurring to the first 2% addition. Egg weight and egg size of hens fed 20%CP plus fat were greater than those of hens fed 16 or 18% CP. Egg weight and egg size of hens fed 18% CP were higher than those of hens fed 16% CP. Daily caloric intake was generally similar among diets except that it was higher in some instances for hens fed the 16% CP diet. These results indicated that added fat increased early egg size even when a high protein diet was fed and that a 16% CP diet that exceeds NRC (1984) percentage requirements did not yield optimum performance of young laying hens.