جستجوی مقالات مرتبط با کلیدواژه « شیر گوسفند » در نشریات گروه « دامپزشکی »

Kefir is a complex probiotic, and a microbial symbiosis collection that is prepared from milk fermentation by kefir grains. The type of substrate (milk) used to prepare this fermented beverage is effective on its biological activities, including its antibacterial activity. The purpose of this study is to investigate the antibacterial activity of kefir samples prepared with cow, buffalo, ewe and goat milk. Activated kefir grains were added to cow (Full-fat and lowfat), buffalo, ewe, and goat milk, and the fermentation process was performed at 25°C and 37°C. After the fermentation process, kefir grains were separated from kefir extract and the antibacterial activity of the extract against 10 pathogenic bacteria was evaluated based on agar diffusion and by the well method. The type of milk used in the preparation of kefir samples at 25°C and 37°C had a significant effect on antibacterial activity against all tested bacteria except S. typhimurium (P<0.05). Kefir samples prepared at 37°C compared to kefir samples prepared at 25°C showed more antibacterial activity. The highest antibacterial activity against the P. aeruginosa, E. faecalis, K. pneumoniae native isolate and B. cereus in the samples prepared with buffalo milk and at the fermentation temperature of 37°C, respectively, with the mean of diameter of inhibition zone of 22, 24.5, 20 and 18 mm was observed. The highest antibacterial activity against S. dysenteriae, S. aureus and S. typhimurium is related to kefir samples prepared with goat's milk and at fermentation temperature of 37°C. The highest antibacterial activity against the standard strain of E. coli, B. cereus, and S. aureus was observed in kefir samples prepared with ewe milk at 37°C. The most sensitive bacteria studied to the samples prepared with full-fat cow's milk were E. coli native isolate and K. pneumoniae standard strain. In the final conclusion considering the antibacterial activity of kefir samples prepared with buffalo, goat and ewe milk, it is recommended to use the milk of these animals as a suitable substrate and substitute for cow's milk to prepare this fermented beverage. Also, it is suggested to perform the fermentation process at 37°C to achieve more antibacterial activity.

Salmonella typhimurium and S. enteritidis are known as the major causes of food-borne infection throughout the world. The present study was carried out to investigate the prevalence of S. typhimurium in raw milks of Chahamaha Va Bakhteyari province. For this reason, a total of 550 raw milks (consisting of 200 cow, 175 sheep and 175 goat milk samples) were collected through October 2011 to March 2012 from dairy herds around Shahrekord. The samples were cultured and the isolated colonies were confirmed by PCR using species-specific ST11 and ST15 primers. According to the results, a total of 20 samples (3.63%) were found positive for Salmonella spp. Amongst, 14 (2.54%) of cow milk, 2 (0.36%) of sheep milk and 4 (0.72%) of goat milk samples were contaminated. Using PCR, 9 (1.63%) samples were contaminated with S. typhimurium. The results indicated a relatively high occurrence of S. typhimurium in raw milks. Therefore, it is essential to maintain hygienic measures during milking and handling. Besides, it is recommended not to use raw milk for the manufacturing of dairy products such as cheese and ice-cream.