Effects of protein, lysine, methionine, calcium, phytase, and strain on performance and profitability of laying hens

Phytates fed to layers result in a substantial amount of unutilized nutrients in manure, especially phosphorus (P) which can cause eutrophication of surface water. Protein in excess of requirement causes excessive release of nitrogen in the environment resulting in foul odor (NH3), and toxicity (NO2 and NO3). Phosphorus and protein are among the most expensive nutrients in poultry diets. Calcium (Ca) is also an important nutrient in that poor eggshell quality due to lack of calcium causes significant losses to the poultry industry each year. Experiments were conducted to determine: (a) the performance of Bovans White hens when fed various diets formulated based on protein or lysine (Lys), (b) the performance and nutrient (protein and Lys) requirements of Hy-Line RTM W-36 hens compared with the new and older strains of Bovans White hens during Phase I (wk 21--36), (c) the nutrient (protein and lysine) requirements of the Bovans White and Dekalb White hens during Phase I (wk 21--36), Phase II (wk 40--52), Phase III (wk 54--65) for optimal performance and profits, (d) the optimal methionine plus cystine to Lys ratios in laying hen diets, (e) the bioefficacy of Methionine Hydroxy Analog-Free Acid compared to DL-Met in laying hens; (f) ability of GMO (NatuphosRTM) and non-GMO (Allzyme Phytase RTM) sources of phytase to release plant-bound phosphorus in commercial layer diets, and (g) the calcium requirement of Bovans White hens relative to Hy-LineRTM W-36 hens.; As the Lys (or protein) content of the diet of Bovans White hens kept at an average temperature of 25.6 C increased, egg weight increased. Egg weight was also higher in diets formulated on protein vs. diets formulated on Lys. Using an economic analysis, for optimum profits, Bovans White hens kept at an average temperature of 25.6 C required 1,076 mg Lys, 750 mg TSAA, 19.1 g protein and 264.2 kcal ME/hen/d during Phase I. These values were higher than the 690 mg Lys, 580 mg TSAA and 15 g protein per hen/d recommended by the National Research Council (NRC, 1994). Egg weight increased as Lys or protein in diets fed to Bovans White hens kept at an average temperature of 20 C during Phase I increased. Egg weight was higher when fed diets formulated on protein than diets formulated based on Lys. (Abstract shortened by UMI.)...