جستجوی مقالات مرتبط با کلیدواژه "لاکتوباسیلوس سالیواریوس" در نشریات گروه "علوم دام"

Introduction: 

Feed additives are commonly used in poultry feed to enhance performance, promote health, and increase nutrient efficiency. The use of antibiotics as growth promoters in poultry feed has been prevalent for years. However, due to concerns regarding the accumulation of antibiotic residues in poultry products and the development of antibiotic-resistant bacterial strains, antibiotics are no longer considered desirable additives in poultry feed. As a non-therapeutic alternative to antibiotics, probiotics have been introduced as suitable candidates to promote growth. Probiotics have beneficial effects on poultry digestive enzymes, improve intestinal absorption, and neutralize toxins produced by harmful microorganisms, ultimately improving the immune system and economic performance. Among the most popular probiotic bacteria are Lactobacilli, as they are generally classified as safe bacteria.

Materials and methods:

 Lactobacillus reuteri (L. reuteri ABRIG25 (MF686485)) and salivarius (L. salivarius NABRII59 (MH595987) isolated from the digestive tract of Guilan’s native chicks and Mazandaran’s duck  respectively, were prepared up to 1.36×109 CFU using MRS medium at 37 ° C, under anaerobic conditions. 300 one-day-old male Arbor-Acres chicks were distributed in a completely randomized design, with 5 treatments, 4 replications (15 chicks per replicate). Experimental treatments were: 1- Basic diet as control group (Cont), 2- Basic diet + 100 g / ton Avilamycin as antibiotic group (Anti), 3- Basic diet + 200 g / ton commercial probiotic (Lacto-feed®) (Plac), 4- Basic diet + 1 g / Kg of L. salivarius NABRII59 (MH595987) bacterial powder (Pls1), and 5- basic diet + 1 g / kg of L. reuteri ABRIG25 (MF686485) bacterial powder (Plr1). Daily feed intake, weight gain, and feed conversion ratio of broilers were determined and recorded in starter, grower, and finisher  periods. On day 42, two chicks were slaughtered from each replicate and the weight of internal organs and carcass cuts were recorded as a percentage of carcass weight. Chicken antibody reaction were determined using SRBS suspension. On days 22 and 35 of the rearing period, two chicks were randomly selected from each cage and 0.1 cc of  SRBC solution was injected into to the wing’s vein, intravenously. Humoral immunity test was applied on days 29 and 42, using 1 cc of blood taken from the wing vein of chickens. The hemagglutination reaction was recorded based on the last two dilutions as SRBC’s antibody using the logarithm and the antibody titer against Newcastle was determined by hem agglutination inhibition (HI) test. On day 42, blood samples were taken randomly from 2 birds per replication to evaluate blood-serum parameters including glucose, cholesterol, triglyceride, HDL, LDL and VLDL. All data were analyzed using SAS software v.9.1 (2012) in GLM procedure using a completely randomized design, and comparison of statistical means was performed, using Duncan's method at the level of 0.05.

The present study investigated the effect of native probiotic isolates (Plr1, Pls1) compared to commercial probiotics (Plac) and antibiotics (Anti) on the growth performance of chickens. The results showed no significant differences in daily feed intake, weight gain, and feed conversion ratio between experimental treatments. However, two native probiotic isolates (Plr1, Pls1), the commercial probiotic (Plac), and the antibiotic (Anti) resulted in a significant reduction (P <0.05) in proventriculus weight, while there were no significant differences in the relative weight of other organs. Both the commercial probiotic (Plac) and the native Lactobacillus isolates (Plr1 and Pls1) significantly improved total immunoglobulin and immunoglobulin G (IgG) levels after both the first and second injections (P <0.05). Lactobacillus salivarius (Pls1) isolate also significantly improved immunoglobulin M (IgM) levels after the second injection. However, there were no significant differences between treatments and the control group in terms of antibody titer against Newcastle disease vaccine, blood glucose, cholesterol, triglyceride, VLDL, and LDL levels. Probiotics can affect gut microbiota by competing for nutrients and attachment sites on the intestinal epithelial cells. Additionally, they may improve blood parameters and stimulate immune system cells to produce cytokines, which play an important role in inducing and regulating immune responses in poultry. Probiotics support lactic acid-producing bacteria and stabilize the gut microflora, which has beneficial effects on feed conversion ratio by stimulating the production of digestive enzymes. Furthermore, probiotics may reduce cholesterol synthesis by fermenting indigestible carbohydrates, leading to the production of short-chain fatty acids and ultimately lowering cholesterol levels in the host bird. Discrepancies in results reported by different researchers may partly be due to differences in chick’s age and breed, level of stress, diet composition, consumption period and duration, type of commercial probiotics, dose or amount of probiotic intake, management skills, and environmental conditions in different experiments.

The general conclusion is that the probiotic isolates used in this study are competitive with the commercial type of probiotics as well as the antibiotic used and are promising as probiotic candidate with beneficial effects on broiler’s performance, blood biochemical parameters and immune system

The effects of lactic acid bacteria as a microbial additive on the fermentation properties of silage are mainly due to the production of beneficial metabolites that can inhibit the growth of pathogenic and destructive microorganisms. Therefore, the ability of a strain to use numerous substrates in forage plants and produced different metabolites can be useful in competition with other microorganisms. This ability can be used as a principle for selecting inoculants. Nevertheless, research has shown that published articles on inoculant selection to limit the growth of these destructive and pathogenic microorganisms are still scarce. Some researchers have reported the effects of microbial inoculants on silage fermentation. However, despite numerous articles on the effects of inoculants on silage fermentation, there is little descriptions for the systematic selection of strains. The aim of this study was to isolate, identify and select strains of lactic acid bacteria with the ability to improve fermentation properties and prevent the growth of pathogenic and destructive microorganisms and evaluate the effect of inoculation of these strains on nutritional value and aerobic stability of maize silages.

This study was performed to select the lactic acid bacterial (LAB) strains isolated from different sources and evaluate their effect on the quality of maize silage. Lactic acid bacteria strains were inoculated to evaluate metabolite production and pH reduction in aqueous extract obtained from maize forage. One hundred and twenty-one strains were isolated from various sources in the laboratory. All isolated strains were gram-positive, catalase-negative and mainly lactic acid-producing, which were considered lactic acid bacteria. 16S ribosomal DNA sequence analysis of 22 representative strains was used to confirm the presence of dominant groups. The sequences of different isolates of lactic acid bacteria had a high degree of similarity to the GeneBank type strains, which showed between 99 and 100% similarity. Four strains of lactic acid bacteria that showed the best results were evaluated in experimental silos. This experiment was performed in a completely randomized design with five treatments (four strains of lactic acid bacteria and one control without inoculum) and nine replications. Inoculants were used in 106 colony forming unit/g of fresh forage to chopped maize forage, which were then ensiled for 105 days. After opening the silos, silages were sampled for analysis of chemical compositions and fermentation products.

Inoculation of lactic acid bacterial strains affected the chemical composition, fermentation properties and microbial population. Inoculation of lactic acid bacterial strains significantly affected the chemical composition and concentration of lactic and acetic acids, ethanol and 1,2-propandiol of silage. Among all treatments, silages inoculated with Lactobacillus fermentum had higher acetate concentration (p < 0.0001), but lactate concentration (p < 0.008) and yeast counts (p < 0.0001) were lower than other silages. Also, inoculation of silage with L. fermentum (strain 16) resulted in silage with higher lactic acid bacterial population and improved aerobic stability after air exposure (p < 0.0001). Silages inoculated with L. fermentum and fallowed by with L. salivarius contained the lowest number of yeasts (p < 0.0001) and filamentous fungi during fermentation. Between silages, silage inoculated with L. fermentum showed higher aerobic stability (p < 0.0001).

The pre-selection method based on the production of metabolites was efficient in selecting new inoculation strains along good correlation with experiments in laboratory silos. Inoculation of lactic acid bacterial strains in maize silage resulted in differences in nutritional value or population of pathogenic and destructive microorganisms. Strains 16 and 7, identified as Lactobacillus fermentum and Lactobacillus salivarius, were considered promising sources for use as inoculants in maize silages because they provide silages with better fermentation properties and improve aerobic stability after exposure to air.