Document Type : Research Articles
Authors
1
Department of Animal Science, Faculty of Agriculture, Shiraz University, Shiraz, Iran
2
Animal Science Research Department, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran
3
Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
4
Animal Science Research Department, Fars Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shiraz, Iran.
5
Animal Science Research Institute, AREEO, Karaj, Iran
6
Islamic Azad University, Fasa Branch, fasa, Iran
Abstract
Introduction: Antibiotics have been used for many years in animal production to treat infectious diseases and as growth promoters. However, the misuse of antibiotics causes problems such as bacterial antibiotic resistance. Also, the possible accumulation of antibiotic residues in livestock products is risky for consumers. After the ban on the use of antibiotic growth promoters in 2006, there was a need to use substitutes in animal feed to replace antibiotics. These alternatives include prebiotics, probiotics, phytobiotics and synbiotics. Probiotics are live microorganisms that, when consumed in sufficient amounts, have beneficial effects on the host by creating a microbial balance in the gut. The purpose of probiotics is to create a competition between the species that are naturally present in the intestinal flora of broilers. The most important advantage of probiotics is that they do not remain in animal products. Prebiotics are feed compounds that are not digested by the host when consumed but can support beneficial bacteria. These compounds are short-chain carbohydrates such as non-digestible oligosaccharides that cannot be digested by animal enzymes. Compounds containing prebiotics and probiotics used in nutrition are called synbiotics. Phytobiotics include a wide range of plant-derived products with bioactive compounds. Plant feed additives (PFAs) are widely effective in improving gut health, increasing digestibility and thus growth performance. These bioactive compounds include secondary metabolites (phenolic and flavonoid). In recent years, various marine organisms have been considered as valuable biological compounds for livestock. Marine algae, due to a wide range of bioactive components such as flavonoid, carotenoid, phenolic compounds, tocopherol, peptide and various sulfated and carboxylated polysaccharides such as alginate and fucoidan with antibacterial, antifungal and antiviruses have beneficial effects on health. Brown macroalgae such as Sargassum angustifolium have beneficial effects on health due to a wide range of bioactive components such as fucoidan, fucose sulfate and polysaccharides. Also, this group of algae is a rich source of sodium alginate oligosaccharides.
Materials and Methods: The present study was conducted in the form of a completely randomized design, lasted for 42 days at the Ali Abad Kamin research farm of the Fars Agricultural and Natural Resources Research and Education Center, Shiraz, Iran. A total of 240 Ross 308 broilers were distributed in five treatments, four replications and 12 birds per replication. The dietary treatments included: 1 basal diet, without additives, 2 basal diet + 0.05% Oxytetracycline, 3 basal diet + 0.2% brown algae Sargassum and treatments 4 and 5 the basal diet was + 1% and 1.5% of synbiotics Limax, respectively. Ingredients and chemical composition of the ration are presented in (Table 1). At the end of each period, chickens in each group were weighed and the average body weight gain (g/b) in each period was calculated. Feed intake in each period was calculated and expressed as g/b/d. Based on weight gain and feed intake in each period, the FCR values of each group were calculated. Tow representative chickens from each group were selected for carcass analysis representing the average weight and variability of each group. The data obtained on various parameters studied during this experimental trial were analyzed statistically with SAS software.
Results and Discussion: The results showed that the treatments had no significant effect on the feed conversion ratio of the birds. In the finisher period (25-42 days) and total period (1-42 days), oxytetracycline and Limax 1% treatments had the highest and lowest average daily weight gain, respectively. There wasn't any significant difference between average daily weight gain of the oxytetracycline treatment and other experimental treatments. In the finisher period, the highest amount of feed intake was for the control treatment and the lowest for the Limax 1% treatment (P<0.05). The highest value of production index was belonged to oxytetracycline and Limax treatments was 1.5% (295 and 272, respectively). The highest abdominal fat percentage in the day 42 was related to Oxytetracycline treatment and the lowest was related to Limax treatment of 1.5% (P<0.05). The highest villus width in the day 42 was belonged to Limax treatment of 1 and 1.5% and the lowest was belonged to Oxytetracycline, control and Sargassum treatments (P<0.05). The treatments did not show a significant difference in the feed conversion ratio. The highest value of production index was observed in oxytetracycline and Limex 1.5% treatments (295.25 and 271.71, respectively).
Conclusion: The final result is that the two oxytetracycline and 1.5% of synbiotics Limax treatments shown the highest average daily weight gain and the production index among the experimental treatments. Also, the maximum width of villi and its absorption surface of villus was related to Limax treatment of 1.5%. Therefore, despite the problems of using antibiotics in the diet of birds, Limax synbiotic supplement can be a suitable substitute for oxytetracycline antibiotic.
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