Abstract
This experiment was conducted to evaluate the effects of dietary methionine (Met) content on the performance of white commercial laying hens and to determine Met and total sulfur amino acids requirements (TSAA). These requirements were estimated using three statistical models (broken-line regression, exponential and second order equations) to evaluate their abilit to determine amino acid requirements. A total of 216 laying hens (23 wks of age) was used in a completely randomized design (CRD) with six treatments with four replicates of nine birds each. The basal diet contained 15.25% crude protein, 2830.16 kcal/kg ME and 0.24% Met. Synthetic DL-Met was added to the deficient (basal) diet in 0.05% increments to make the other five experimental diets (0.29, 0.34, 0.39, 0.44 and 0.49% Met). Increasing Met level from 0.24 to 0.34% significantly increased egg production, egg weight, egg mass, egg content, and feed intake and decreased feed conversion ratio (p<0.05). However, further Met increases, from 0.34 to 0.49%, no longer influenced these parameters. Out of the three models, the broken-line regression model presented better estimates of AA requirements. Based on broken-line equations, average Met and TSAA requirements of the laying hens were 0.31 and 0.60% (245.50 and 469.25 mg/hen/day) from 22 to 36 wks of age, respectively.
Highlights
The efficiency of dietary protein utilization depends on the amount, composition, and digestibility of the amino acids (AA) in the diet
Methionine and total sulfur amino acids requirements (TSAA) requirements estimated by exponential equations for egg mass (EM), egg content (EC), feed conversion ratio (FCR) and feed intake (FI) were higher than maximum dietary Met and TSAA supplied in this experiment (0.49 and 0.77%, respectively; Tables 2 and 3)
Methionine and TSAA requirements estimated by second-order equations, irrespective of the results, were very variable (Tables 4 and 5)
Summary
The efficiency of dietary protein utilization depends on the amount, composition, and digestibility of the amino acids (AA) in the diet. It is important to formulate diets according to accurate values of amino acid requirements. Lopez & Leeson (1995) reported that since chickens can only utilize about 40% of the dietary protein, it seems logical to decrease dietary protein level in the diet, which would minimize nitrogen excretion. Synthetic AA need to be added to the diet in order to meet the requirements of limiting AA due to AA dilution when dietary protein is reduced. Formulating diets based on the ideal protein concept is one of the methods to reduce dietary protein, which, in turn, will decrease fecal nitrogen excretion, while maintaining egg production parameters (Novak et al, 2006)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
