Effect of the level of digestible lysine and the ideal amino acid profile on the lysine requirement in Hy-Line W-36 hens at the end of the first laying cycle

Abstract

THE OBJECTIVE OF THE STUDY WAS TO EVALUATE THE EFFECT OF DIGESTIBLE LYSINE LEVEL AND THE ADDITION OF CRYSTALLINE AMINO ACIDS, ON PRODUCTIVITY, NITROGEN UTILIZATION AND LYSINE REQUIREMENT, USING AN EMPIRICAL AND A FACTORIAL APPROACH IN LAYING HENS. HY-LINE W-36 LAYERS FROM 60 TO 65 WEEKS OF AGE WERE USED. IN EXP. 1, FOUR INCREASING LEVELS OF LYSINE WERE TESTED IN DIETS BASED ON SORGHUM AND SOYBEAN PASTE: 0.40%, 0.53%, 0.66%, AND 0.79%. THERE WERE 6 REPLICATES PER TREATMENT WITH 2 HENS IN EACH. IN EXP. 2, PREVIOUSLY USED DIETS CONTAINING 0.66% AND 0.79% OF LYSINE WERE TESTED AND TO BOTH CRYSTALLINE AMINO ACIDS WERE ADDED TO MATCH OR SURPASS BY 10% AN IDEAL AMINO ACID PROFILE. THERE WERE 5 TREATMENTS WITH 6 REPLICATES, WITH TWO HENS IN EACH. THE EXPERIMENTS LASTED FOR 21 DAYS; IN THE LAST 5 DAYS, NITROGEN BALANCE WAS CARRIED OUT. IN BOTH EXPERIMENTS, PRODUCTIVITY WAS INCREASED (EXP. 1, P < O.01; EXP. 2, P< 0.05) AS THE LEVEL OF DIETARY LYSINE INCREASED. IN EXP. 1, THE LYSINE REQUIREMENT/G OF EGG MASS DECREASED (P<0.01) AS THE LEVEL OF DIGESTIBLE LYSINE IN THE DIET INCREASED. IN EXP. 2, THE AMINOACID PROFILE DID NOT AFFECT ANY OF THE RESPONSES EVALUATED. IN SUMMARY, IN HY-LINE W-36 HENS FROM 60 TO 65 WEEKS OF AGE THE ESTIMATED REQUIREMENT OF DIGESTABLE LYSINE/G OF EGG MASS WAS 12.96% MG AND THIS REQUIREMENT WAS NOT AFFECTED BY THE IDEAL AMINOACID PROFILE.