عنوان مقاله [English]
Introduction: Several studies have been performed in order to improve feed utilization and reduce the feed costs. For this purpose, various additives have been used to improve the health and production performance of poultry. Barley malt extract is one of the additives that has recently been introduced for using in domestic animal feeds. Barley malt extract is produced from barley grains through a process called the malting. Malting is the process of cereal grains germination that have been dried. The germination starts by soaking barley grains in water. The malting process make changes in barley, which involves the alteration and degradation of phenolic compounds and the production of Maillard reaction products, which have a significant effect on the antioxidant content of malt. Malt is known as a natural source of antioxidants, B vitamins and minerals such as iron, zinc, calcium, magnesium and phosphorus. Malt extract is available in both powder and liquid forms, the liquid form of that is thick syrup and has been used extensively for several applications, such as brewing, baking, food flavoring or as an appetizer. The results of previous study showed that adding malt extract to the broiler diet can improve performance of broiler as well as villus width and villi surface area. However, based on our literature review there is no data available to evaluate the effect of adding barley malt extract on the performance of laying hens. Therefore, the aim of this study is to evaluate the effects of adding different levels of barley malt extract to the diet on performance, egg quality, immune response and intestinal morphology of laying hens during 29 to 46 weeks of age.
Materials and Methods: In this study, 432 Hyline W36 laying hens were used in a completely randomized design with three treatments and six replicates of 24 birds each, for 18 weeks. The experimental treatments included 0, 0.2 and 0.4% barley malt extract levels. Feed intake, feed conversion ratio, egg production, egg mass, egg weight, shell thickness and strength, shell weight and internal quality characteristics of eggs were evaluated during the experiment. In addition, antibody titers against sheep red blood cells (SRBC), Newcastle and influenza viruses were measured two times at specific intervals after the respective vaccinations. At the end of the experimental period after slaughter, 2-cm segment was separated from the jejunal region anterior to Meckel’s diverticulum. Tissue samples were evaluated for the villus height, villus width, crypt depth, villus height:crypt depth ratio (VH:CD), villus surface area, muscular layer and epithelial layer.
Results and Discussion: The results showed that although percentage of egg production, egg weight and egg mass were not affected by the experimental treatments, but adding malt extract numerically showed better egg production persistency at the end of experimental period. Also feed conversion ratio and feed intake in the laying hens at 28 to 46 weeks of age (peak production and post-peak) were not affected by the experimental treatments. Egg shell thickness (P<0.001), haugh unit(HU) index and yolk height (P<0.01) were affected by experimental treatments, briefly treatments supplemented with malt extract showed higher egg quality for mentioned criteria as compared to the control group. Furthermore the treatments supplemented with barley malt extract numerically increased eggshell strength (P=0.076). Total antibody concentration against SRBC and Immunoglobulin G (IgG) increased in the treatments supplemented with 0.2 and 0.4% barley malt extract during the primary period (p < 0.05). Antibody productions were not affected against the Newcastle viruses. In the first period of the experimental treatment antibody production were affected against influenza viruses; briefly, the highest antibody production was related to those birds that fed with the control diet. In addition, the results show that supplementation of barley malt extract in the diet can increase the villi height, villi height to crypt depth ratio and villi surface area. Villus width, crypt depth and muscular and epithelial layer were not influenced by adding barley malt extract to the laying hen diet.
Conclusion: The results of this study showed that adding barley malt extract to the diet of laying hen may improve egg quality and antibodies production against SRBC. Furthermore, barley malt extract may increase the villus height, villus height: crypt depth ratio and villi surface area, and consequently improve the digestive capacity of laying hens.
. Adhikari, P., and W. Kim. 2017. Overview of prebiotics and probiotics: focus on performance, gut health and immunity. Annals of Animal Science, 17.4: 949-966.