mohammad faseleh jahromi

Nowadays, due to the high application of antibiotics, the emergence of pathogenic microorganisms resistant to antibiotics is considered a serious threat to poultry production industry. Therefore, reducing the use of antibiotics and using antibiotic alternatives is one of the main strategies to fight antibiotic resistance. Meanwhile, yeast-based prebiotics have been proposed as one of the best alternatives to antibiotics. The most important yeast-based prebiotics include hydrolyzed yeast, partially-hydrolyzed yeast, inactive yeast, yeast cell wall, yeast extract and autolyzed yeast. Yeast-based prebiotics contain functional compounds in various concentrations such as B vitamins, beta-carotene, ergosterol, ascorbic acid, polyamines, mycosins, enzymes, beta-glucans and mannan oligosaccharides, depending on the production and processing method. Yeast-based prebiotics are resistant to the acidic and alkaline conditions of the digestive system, and by inactivating pathogenic microorganisms, improving the immune system, stimulating the growth of probiotics, helping to establish beneficial microbial flora in the digestive system, and stimulating the production of volatile fatty acids, reducing intestinal acidity, improving the growth and differentiation of intestinal villi, stimulating the production of enzymes, increasing the production of antimicrobial peptides improve the production efficiency in poultry. Prebiotics also play a significant role in reducing the feed conversion ratio and mortality in poultry production industry.

Today, fungal toxins or mycotoxins are a major problem in the food industry and food chain safety, which can contaminate a wide range of agricultural products, and thus they have negatively affect on health and production of livestock and poultry, and consequently human health, the economies of countries and even international trade. Since mycotoxin contamination cannot be completely prevented before or after harvest, it is important to know exactly how to remove mycotoxins during technological processes and feed clearance strategies. Today, the biological control of mycotoxins by microorganisms and other biological factors is becoming a valid approach to protect food products from contamination by these toxins, which increases the safety and quality of crops and animal feed, and ultimately reduces toxin concentration in animal products (milk, meat and eggs), and increase food chain security.

This study was contacted to evaluate the effects of replacement of inorganic zinc with organic zinc on the growth performance, immune system, antioxidant status, morphology of jejunum, and tissue zinc retention in broilers. The number of 150 Ross 308 broilers were used in a completely randomized design with Duncan's test at the statistical signification level of 0.05, in 3 treatments and 5 replicates and 10 birds in each replicate. The treatments wear: 1) basal diet based on corn and soybean without zinc 2) basal diet + 22 mg/kg organic zinc + 88 mg/kg zinc sulfate 3) basal diet + 33 mg/kg organic zinc + 77 mg/kg zinc sulfate. At day 42 of the experiment, one bird from each replicate was sacrificed and used for analysis. The results showed that replacement of inorganic zinc with organic zinc had no significant effect on the growth, feed intake, and feed conversion ratio of broilers. Also, it did not have any significant effect on the amounts of immunoglobulins (IgG, IgM and IgA). However, the antioxidant evaluation showed that the usage of organic zinc can respectively increase and decrease the amounts of superoxide dismutase and Malondialdehyde in the liver. Besides, morphological evaluation of intestine indicated that the organic zinc improved the villi height and width. In general, it seems that the usage of organic minerals, such as zinc, in the diet of boilers improves their immune system and antioxidant status.

Due to growing demand of human communities for livestock products, livestock farms have trended towards industrialization.Therefore, with increasing livestock production, the use of highly fermentable carbohydrates has increased in livestock diets. On the other hand, the incompatibility of the gastrointestinal tract of ruminants with this feeding method causes the occurrence of various metabolic diseases and reduces the herd's economic longevity. Research has also shown that adding antibiotics to cow diet increases growth, reduces feed conversion ratio, and improves production and reproduction. But the use of antibiotics for long-term increases antibiotic resistance in livestock and consumers of livestock products. Therefore, it seems necessary to find a suitable alternative to antibiotics such as probiotics. The use of yeast in ruminant nutrition improve to establish and maintain the balance of beneficial bacterial populations, increase fiber digestion, improve ruminal function, ruminal pH and reduce the occurrence of various metabolic diseases. Yeast diets have also to improve milk production performance, persistence in dairy cattle, and milk quality. Probiotics can reduce the risk of intestinal infections and inflammation by competing for food, producing antimicrobial compounds, neutralizing toxins produced by these microorganisms. Also, the presence of effective compounds such as beta-glucans and mannas in the yeast cell wall reduces poisoning by fungal toxins, especially in ruminants, and by stimulating the immune system and the production of digestive enzymes, plays an important role in the growth performance, production, reproduction and the immune system in ruminants.