| چکیده انگلیسی مقاله |
Introduction: Organic acids are compounds that can be considered as a replacement for antibiotics. Butyric acid is known as the main stimulant of intestinal wall tissue and modulator of normal intestinal microflora (Van Immerseel et al. 2004). Butyric acid is also the main source of energy for intestinal cells and is essential for the development of gastrointestinal-related lymphoid tissue (Friedman and Bar-shira, 2005). The positive and beneficial effect of butyric acid on the functional traits of broilers has been reported (Leeson et al. 2005; Antongiovanni et al. 2007). Butyric acid is a highly volatile and highly smelling compound, much of which is absorbed at the beginning of the gastrointestinal tract (Bolton and Dewar, 1965). The effects of butyric acid appear to improve if it is protected from absorption in the upper gastrointestinal tract (Leeson et al. 2005). For this purpose, butyric acid glyceride along with butyrate-calcium was used in this study. Calcium butyrate is a protected form of butyric acid that is produced using a new technology by Kimia Daroo Mehr Company in Tehran, Iran. This product passes intact through the gut and after decomposition by the pancreatic lipase is absorbed in all different parts of the intestine. Calcium butyrate is a bio-odorless substance and contains 70% butyric acid. butyric acid glyceride (C4) is the brand name of butyroglycerol (Sanadam Pars, Tehran, Iran). Butyric acid is esterified with a glycerol molecule and the resulting compound has a very stable structure. After consumption by animal, pancreatic lipase, it is broken down to the constituents and is absorbed. The aim of this experiment was to investigate the effects of different dietary supplementation levels of calcium butyrate, butyric acid glyceride and their mix on growth performance, carcass traits and jejunal morphology in broiler chickens. Materials and methods: A total of 400 one-d-old broilers from Ross 308 strain were allotted to 10 dietary treatments, 5 replicates and 10 broiler chicks per each, from 1 to 42 days of age. Experimental diets included: control (without additives), and supplementation of calcium butyrate (0.15, 0.30 and 0.45% of diet), butyric acid glyceride (C4) powder (0.15, 0.30 and 0.45% of diet), and three levels of calcium butyrate and C4 powder mixture in equal proportion (0.075+0.075, 0.15+0.15, and 0.225+0.225% of diet). Light was provided as 23 h light and 3 h darkness. Rearing house temperature was set at 32°C on day one, and then decreased by 3°C per weak to reach 21±2 °C and remained constant until the end of the experiment. During the experimental period, feed and water were provided ad libitum. Mortality were collected, weighed and recorded daily. At the end of each period, the amount of feed consumed and the group weight of the chickens in each pen were recorded and feed conversion ratio was calculated after adjusting for dead birds. In order to evaluate the morphology of the small intestine at the age of 24 days, one chick per pen close to average pen weight was selected and slaughtered. About one centimeter was removed from the middle part of the jejunm tissue and placed in 10% formalin solution and sent to the laboratory. At the end of the rearing period (42 days), after weighing the chickens, one chick was selected from each replication and slaughtered to measure carcass traits. Data were analyzed in a completely randomized design using General Linear Model procedure by SAS (2009) statistical software. The treatments mean was compared using Duncan's multiple range test at P < 5 %.Results and Discussion: The average body weight of chicks at the age of 10 days and the mean daily weight gain of 1-10 days in the groups receiving the mixed powder C4 and calcium butyrate (0.225+0.225% of diet) was significantly higher than the control group (P< 0.05). However, the effect of experimental treatments on body weight at 24,42 days of age, and the weight gain at 11-24, 25-4, and 42-1 days of age was not significant (P> 0.05). The feed conversion ratio (FCR) at the age of 1-10 and 1-42 days in control treatment was significantly higher than other treatments (P < 0.05). Treatment with mixed powder c4 and calcium butyrate (0.225+0.225% of diet) had the highest relative hepatic weight and lowest abdominal fat weight compared to other treatments (P< 0.05). Regarding to the morphological traits of the small intestine, the highest thickness of the muscle layer was observed in the control treatment (P< 0.05). Iincreasing villus length can be attributed to the reduction of pathogenic bacteria. Increasing the length of villus increases the digestibility and absorption capacity of nutrients, and since this increase in jujumen, which is the main source of digestion and absorption of nutrients in birds, can be concluded that it is likely the use of organic acids can have beneficial effects on the digestion and absorption of food and subsequently the performance of the birds. In this study the thickness of the muscle layer in the treatment of organic acid intake was reduced, it can be concluded that the use of organic acid supplementation with the effects on the pH gastrointestinal tract probably reduced the pathogenic bacteria in the intestine. By reducing the number of pathogenic bacteria in the intestine and making it healthier, it requires a thinner epithelium to protect the surface of the intestine, which is likely to result in a thickening of the muscle layer thinner. Given that most of the additives that have been introduced as growth promoters have been shown to have an impact on the performance of broiler chickens due to antimicrobial activity and the effect on the microbial flora of the digestive tract. Therefore, breeding conditions and the rate of infection of birds with pathogenic bacteria in the test can be as a result of the test. Each of these additives has different levels of compounds and levels, the dosage and the ingredients used in the experiment can also be effective in the various results obtained from using these growth stimulating agents.Conclusion: In general, the results of this experiment showed that the addition of butyrate-calcium and glyceryl butyric acid to the diet alone or combined with each other, with a positive effect on digestion and absorption of nutrients, could improve the growth performance, some carcasses components and Morphology of small intestine of broiler chicks. The difference in the results of the research may be related to the different buffering capacity of the experimental diets or the type and amount of organic acids used in the experiments. |