Relationship between Dietary Protein Levels and Betaine Supplementation in Laying Hens

Abstract

The effects of betaine supplementation on productivity, egg quality, blood components, and liver amino acid concentration were examined in laying hens using a diet with differing levels of CP. A total of 540 Hy-Line Brown laying hens were allotted to 6 treatments with 5 replications for 24 weeks. Treatments were designed with 3 levels of CP (14, 16 and 18%) and 2 levels of betaine supplementation (0 and 600 ppm) in the diet. Egg production, egg mass, and feed conversion were found to be improved significantly as dietary levels of protein increased (P<0.05), but the results for betaine supplementation were different. Eggshell breaking strength, eggshell thickness and Haugh units were not influenced by the supplementary betaine or the level of CP. Serum albumin concentration was significantly elevated in the group fed with 18% CP compared to those in groups fed with other amounts of CP (P<0.05). Supplemental betaine did not affect serum total protein, albumin, or BUN concentration, whereas the uric acid concentration was significantly increased in the betaine-fed groups (P<0.05). Concentrations of liver amino acids were influenced by CP levels and dietary betaine supplementation (P<0.05). In addition, betaine supplementation increased the methionine, aspartate, cystine, glutamate, glycine, proline and tyrosine levels in the livers of birds fed on the 14% CP diet (P<0.05). These results suggest that betaine does not increase productivity, but may affect serum uric acid and liver amino acids in laying hens. Betaine also increased liver amino acid levels in the lower CP groups.