نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، دانشگاه بیرجند
2 عضو هیئت علمی
3 گروه علوم دامی، دانشگاه فردوسی مشهد
4 دانشیار گروه علوم دامی، دانشگاه بیرجند
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Extended abstract
Introduction: Methionine is an essential amino acid that has a vital role in many physiochemical processes in birds. It is the first limiting amino acid in birds fed with corn-soybean diets. A deficiency of methionine can lead to reductions body weight, egg production, egg weight, and egg mass in laying hen. However, some methyl donor compounds such as choline and betaine can partially substitute for methionine in certain reactions and partially compensate for the effects of methionine deficiency. Therefore, the aim of this study was to evaluate the effects of supplementing betaine and choline to diets with reduced methionine levels on production and egg quality, blood indices and blood and egg antioxidant status in laying hens.
Material and methods: In this experiment, 315 Bovans strain laying hens were arranged in a completely randomized 3x3 factorial design including three levels of methionine (80, 90, and 100 percent methionine) and three supplements (no supplement, 0.15 percent betaine, and 0.15 percent choline) with 9 treatments and 7 replications and 5 hens for each replication. Following a 10-day adaptation period, the birds were randomly assigned to experimental units after 10 days adaptation. The birds fed with dietary treatments in two periods of 28 days. In the last two days of each period, 4 eggs from each replication were collected to evaluate the egg quality traits, including egg shape index, specific weight, Haugh unit, yolk height, yolk color index, relative weight of yolk, albumen and eggshell, and eggshell thickness. The blood samples were gathered from two birds of each replicate at end of experimental period to determine the biochemical indices. The data were analyzed by SAS software with GLM.
Results & Discussion: The results revealed significant interaction between treatments. Birds fed with fed diets containing 100% methionine had the lowest feed conversion ratio (P<0.05) and the highest egg mass compare to those fed diets contained 80% Met, at 32-35 weeks of age (P<0.01). At 36-39 weeks of age, birds fed 100% Met exhibited the highest egg weight (P<0.01). The yolk color index increased in birds fed 100% Met with 0.15% betaine level and the 90% Met with 0.15% choline level, at the end of first and second periods, respectively (P<0.01). Blood cholesterol and triglyceride concentration decreased in birds fed the 90% level without supplementation (P<0.05). Diets containing 100% Met and 15% betaine treatment decreased yolk cholesterol concentration (P<0.01). These results indicate that recommended methionine level is necessary to maintain egg production and egg mass.
Conclusion: It is concluded that a 100 % of Met in laying hens is need to maximize the egg production traits. However, adding betaine to a low-methionine diet has a positive effect on egg quality, and choline supplementation may improve antioxidant status in the blood and eggs.
کلیدواژهها [English]
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