The effect of diets containing different levels of yeast cell wall on production performance, eggshell quality and immune response in broiler breeder's

Introduction: The use of growth-promoting antibiotic substitutes in commercial broiler farming is mainly due to the development of resistant bacteria. The use of growth-promoting antibiotics in mother hens may have important consequences, one of these effects being the reduction of the effect of antibiotics in the offspring whose parents received these antibiotics (McDonald 1995, Ghasemian and Jahanian 2016). One of the proposed alternatives to growth-promoting antibiotics are prebiotics, which include non-starch polysaccharides that are not digested in the digestive system, including fructo-oligosaccharides, galactoligosaccharides, beta-glucan, mannan oligosaccharides, etc. The main components of the yeast wall are beta-glucans and mannan oligosaccharides. which are of special importance in feeding broiler breeders because it not only changes the intestinal microflora for the benefit of the animal, but also has properties to modulate the immune system (Arsi et al. 2015). The use of cell wall yeast promotes the growth of beneficial bacteria throughout the digestive tract. Among the different probiotic species, lactobacilli and bifidobacteria use the yeast cell wall the most and grow the most when it is used (Liu et al. 2018) and also have a greater contribution to poultry health (baurhoo 2007b). Increasing the number of useful cells in the intestine reduces the number of harmful bacteria. On the other hand, the mannan present in the yeast cell wall reduces the binding of Gram-negative bacterial pathogens such as salmonella and E-coli to the intestinal epithelial cells by binding type one fimbriae. Bacteria colonize the intestine without attachment and colonization, and it is directly related to the strengthening of the animal's immune system (baurhoo 2007b). It has also been reported that the mannan fraction present in the yeast cell wall has anti-adhesion activity against Campylobacter jejuni (Ramirez-Hernandez et al., 2015; Corrigan et al., 2017).
Materials and methods: In order to investigate the effect of different cell wall yeast levels of Saccharomyces cerevisiae in feeding broiler breeders, cell wall yeast product was prepared from Chitika Company. For this purpose, 100 broiler breeder and 25 broiler roosters (Ross 308) 54 week olds were prepared and randomly distributed in 5 treatments and 5 replications with 25 experimental units (4 broiler breeder and one rooster in each unit). The experimental treatments included 1- the control treatment (without Saccharomyces cerevisiae yeast cell wall) and treatments 2 to 5 containing 0.5, 1, 1.5 and 2 g/kg of Saccharomyces cerevisiae yeast cell wall in feed respectively. The duration of the experiment was 12 weeks, which was divided into 3 periods (age 54-57, 58-61, and 62-65 weeks), and the birds had free access to water and food during the entire experiment. Room temperature, lighting duration and other management items were based on the standard of the strain guide (birds had the same amount of feed). The experiment was divided into three periods of four weeks according to the different stages of the birds' production, and for this purpose, at the end of the 4th, 8th and 12th weeks, the birds were weighed and the average weight of each group was reported. The eggs of all experimental treatments were counted and collected separately in the whole period. In order to determine production performance, production percentage and average egg weight were measured and calculated daily in the entire period and the results were reported. In order to check the quality characteristics of eggs, at the end of the 8th and 12th week, 2 eggs were randomly selected and evaluated from each replication, and the average of these two weeks was reported in the results of this study. The resistance of the egg shell was measured using a Japanese resistance measuring device with specifications (Co., Ltd., Tokyo, Japan Robotmation) in which the eggs were placed vertically and the egg cracked due to the applied force and the applied force It was measured in kilograms per square centimeter.
Results and discussion: The experimental treatments had no significant effect on the weight changes of broiler breeders. The results showed that the experimental treatments had significant effects on the percentage of egg production in all three test periods. In the first period of the experiment, the group fed with 1.5 and 2 g/kg with 63.97 and 63.54 percent egg production had a significant difference compared to the control group which had 62.35 percent production. In the second period (age 58-61 weeks), the group fed with one g/kg of Saccharomyces cerevisiae yeast had a significantly higher percentage of egg production than the control group. In the third period, the groups receiving Saccharomyces cerevisiae yeast had a significantly higher percentage of egg production than the control group. Different levels of Saccharomyces cerevisiae yeast did not have a significant effect on shell resistance and thickness in broiler breeders compared to the control group. The test results show the effect of treatments containing 1, 1.5 and 2 g/kg of Saccharomyces cerevisiae cell wall causing a significant reduction in the number of broken eggs. The use of levels of 1, 1.5 and 2 g/kg of cell wall yeast in the diet caused a significant increase in the antibody titer of Gambro virus in broiler breeders during the experimental period.
Conclusion: The results of this study showed that in the three defined experimental periods of 54-57, 58-61 and 62-65 weeks, experimental treatments had no significant effect on body weight changes. Treatments containing 0.5, 1, 1.5 and 2 g/kg of Saccharomyces cerevisiae wall yeast significantly increased the percentage of eggs produced compared to the control group, as well as the effects of decreased production due to aging in the feeding groups. It was less with yeast cell wall. Experimental treatments had no effect on average egg weight, egg resistance and shell thickness. The percentage of deformed and broken eggs in the groups receiving 1, 1.5 and 2 g/kg of cell wall yeast significantly decreased compared to the control group. In general, according to the results obtained from this research, it can be said that the use of commercial yeast Saccharomyces cerevisiae has favorable effects and also the best level used is 1 g/kg of feed.