Effect of lysine supplementation to low protein diet and its influence on production performance, egg quality and humoral immune response of White Leghorn layers

摘要

A study was conducted to evaluate the effect of supplemental lysine to low protein diet on egg production, egg quality and humoral immune response of White Leghorn layers. A basal diet based on maize-soybean meal-sunflower cake meal (14.4% CP, 0.60% lysine) was formulated, which was adequate in all essential amino acids except lysine. Subsequently, five test diets were formulated by supplementing synthetic lysine (L-lysine HC1) at 0.0, 0.05, 0.10, 0.15 and 0.20% which resulted in five graded concentration of lysine (0.6, 0.65, 0.7, 0.75 and 0.8%, respectively). Each diet was fed ad libtum to 6 replicates of 5 birds each in cages. A lighting regime of 16h was provided and all ^he layers were kept under uniform management conditions throughout the experimental period (28-44 wks). Lysine at 0.60 to 0.70% in the diet was not adequate to maintain the performance parameters (egg production, egg weight and feed efficiency except body weight gain) or humoral immune response (antibody titre to SRBC inoculation and ND vaccine). Increasing dietary concentration of lysine to 0.75% significantly (P<0.05) improved egg production and egg weight, humoral immune response and feed efficiency. Further dietary increase of lysine to 0.8% did not enhance the performance and immune response. Egg quality measure such as Haugh unit score and albumen content increased, while the yolk content decreased significantly (P<0.05) as the dietary lysine increased from 0.6 to 0.75%. The birds in the 0.75% lysine dietary group consumed about 14.8 g protein and 771 mg of lysine per bird per day. Considering lOOg feed consumption per day, it is concluded that the diet with 14.8 % and 0.77% lysine was adequate to realize optimum performance with good albumen quality and better immuneresponse in layers during 28-44 wk of age.