In order to determine the digestible threonine requirement of laying hens fed with wheat-soybean diet in the second period of experimental production using 384 pieces of laying hens of the Highline W36 strain in the form of a completely randomized design with six treatments, eight replications and eight pieces of birds in each replication in the age period It was done between 105 and 116 weeks.

The experimental treatments included adding L-threonine to the diet in order to provide six levels of digestible threonine of 0.44, 0.46, 0.48, 0.50, 0.52 and 0.54%, so that the ratio of threonine to lysine in the diet 60, 63, 66, 69, 72 and 75% were obtained in the experimental tests. The effect of the level of digestible threonine in the diet on the laying percentage, gram of eggs produced per day and the feed conversion ratio was significant as a quadratic equation and on the average egg weight. By increasing the concentration of digestible threonine in the diet to the level of 0.48%, the laying percentage and gram of eggs produced per day increased and the feed conversion ratio improved.

Using the regression models of the digestible threonine requirement of laying hens in order to optimize the percentage of laying eggs, grams of eggs produced per day and the feed conversion factor are respectively 502, 505 and 517 mg per day (equivalent to 9.57 mg per gram of eggs produced) Estimated.

The general result is that in wheat-soybean diets for the second period, the production of threonine is the limiting amino acid, the amount of digestible threonine required for the optimal occurrence of the feed conversion ratio is higher than the laying percentage and gram of eggs produced. Providing digestible threonine level of 0.48% (ratio of threonine to lysine is 66%) is recommended.

Authors: Seyyed Amir Hosseininejad Haider Zarghi Abulqasem Gulian

Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran

Click to view more content.