Response to amino acid supplementation by laying hens

The aim of the present study was to test the recommendations of the Gesellschaft fur Erndhrungsphysiologie (GFE, 1999) (German Society for Nutritional Physiology) for the amino acids lysine and methionine over a laying period of hens over 13 months. A total of 810 hens were allocated to 15 groups with 54 hens per group. Hens were kept individually in a cage battery. The experiment commenced when the hens were 22 weeks old. Laying hens were fed either according to the principles of universal feeding or according to a three phase feeding program. The content of lysine or methionine, or both amino acids, was reduced or increased by 15% in the diet. Furthermore, one hen group was fed according to the amino acids recommendations for poultry of the Nutrition Research Council (NRC, 1994). The lowest feed intake of hens was found in the groups which were fed according to the recommendations of NRC and in the groups which were fed diets with 15% reduced lysine or methionine content. Laying intensity increased parallel to feed intake. The reduction of the concentration of lysine or methionine in the universal diet decreased laying intensity. Hens fed in three phases showed a higher laying intensity in comparison with the universally fed hens. Egg mass was most strongly reduced with a reduced lysine content in the diet with universal feeding. The 55.1 g daily egg mass production of hens from the group Phase-GFE + 15%Lys was the highest. Additional supplementation of 15% methionine in the diet did not improve these results further more. According to regression analysis, the hens have to ingest 800 mg lysine and 460 mg methionine to produce 55 g egg mass daily. The lowest feed efficiency of 2.15 - 2.18 g/g was calculated for the groups Universal-GFE + 15%Lys, Universal-GFE + 15%Lys/Met and Phase-GFE + 15%Lys. The breaking strength of the eggs was the same for all groups at the end of the test.