Exigência de metionina + cistina na alimentação de poedeiras comerciais leves no segundo ciclo de produção em clima quente e úmido

Abstract

The present study aimed to determine the requirement of methionine + cystine for commercial laying hens in second production cycle. This study will be developed in the facilities of Poultry Sector, College of Agrarian Sciences, Federal University of Amazonas, Manaus, Amazonas, Brazil. The experimental period lasted 105 days, divided in five cycles of 21 days each. One hundred forty-four Hisex White laying hens with 84 weeks were distributed in a completely randomized method with six treatments constituted by levels of methionine + cystine (0.45; 0.50; 0.55; 0.60; 0.65 and 0.70%) and four replicates with six birds each. For performance, in each cycle, were analysed the feed intake (g/bird/day), feed conversion (kg/dz), feed conversion (kg/kg), egg production (%), egg mass (g) and viability or survival rate (%). In the last two days of each cycle, two eggs of each plot were collected and identified to measure the egg weight (g), specific gravity (g/cm3), yolk (%), albumen (%), shell (%), albumen height (mm), yolk height (mm), shell thickness (m), yolk pigmentation, Haugh unit and strength to break the shell (N). The data collected were subjected to variance analysis and the estimates of treatments were submitted to polynomial regression analysis to 0.01 and 0.05 of significance by software SAS. It was observed that the best inclusion level was 0.65%, where a significant effect (p <0.05) was analyzed for the parameters energy consumption, protein consumption and quadratic effect (p <0, 05) in egg production and egg mass. For the eggs quality parameters, the internal quality of the eggs showed a positive linear effect (p <0.05) at the albumin height and in the color of the yolk. In the external quality of the eggs, differences (p <0.05) were observed in% shell, shell thickness and shell resistance. The results showed a quadratic effect (p <0.05) for glucose and blood triglycerides, demonstrating that when birds present adequate nutritional conditions to ensure a good recovery, they have a better return to the productive stage. Therefore, the 0.65% methionine + cystine level was considered in this experiment as the ideal for inclusion in diets for light commercial laying hens in the second production cycle.