جستجوی مقالات مرتبط با کلیدواژه "دما" در نشریات گروه "علوم دام"

There is a shortage of animal feed and water resources in several developing countries. Thus, proper use of agro industrial by products is a useful means to overcome this problem. Agricultural by products can use as animal feeds, but because of high lignin and low protein content, their digestibility and palatability is low. Several processing method has been used to improving nutritive value of such materials (Rahal et al. 1997 and Fazaeli et al. 2004). Recently, biological delignification of lignocellulosic material has been considered as an alternative approach (Fazaeli et al. 2004). Termites gut contains different kinds of lignocellulose degrading microbes, which the possibility of their use in improving the nutritive value of agricultural by-products is a major step in compensation of animal feed shortage.
Material and The present study was conducted to determine the optimum temperature and pH for growth of symbiont bacteria degrading lignocellulosic material isolated from termite gut, and to investigate their effects on the digestibility and in vitro fermentation parameters of wheat straw (WS) and date leaf (DL). For this purpose, three bacteria including Bacillus licheniformis, Ochrobactrum intermedium and Microbacterium paludicola were used, which isolated by culture of termite guts contents in mediums containing different types of lignin and lignocellulosic materials. Sterile basal media was used as a medium for isolation process and contained the following ingredients per litre: 7.0 g K2HPO4, 3.0 g KH2PO4, 1.0 g (NH4)2SO4, 0.1 g MgSO4·7H2O (Borji 2003). Growth curves of isolated bacteria for optimum temperature and pH were obtained using nutrient broth medium. Three temperatures of 30, 37 and 40 oC and four pH of 5, 6, 7 and 8 were evaluated. After that, WS and DL were processed with these isolates in media 9 (M9) medium with following composition (per litre): 6.2 g Na2HPO4, 3.0 g KH2PO4, 0.5 g NaCl, 1.0 g NH4Cl (Kato et al. 1998). After processing, residues were collected, dried and used for in vitro gas production experiment according to Makkar (2010). For this purpose, rumen liquor was collected from two ruminally fistulated cows. Animals were maintained on a 60% hay and 40% concentrate diet according to their requirements for two weeks. Rumen contents were collected from the ventral sac of rumen before morning feeding. A completely randomized design was used to determine the optimum temperature and pH for bacterial growth as well as effects of different bacteria on in vitro gas production and fermentation parameters of treated substrates. Data were analyzed by General Linear Model (GLM) procedures of SAS (SAS Institute, 2001),
All of isolates were capable of grow at all of examined temperatures (i.e., 30, 37 and 40 oC). The optimum growth of B. licheniformis occurred at 40 oC, but the optimum growth of O. intermedium and M. paludicola was observed at 37 oC. All of isolates grew at different pH ranges (i.e., 5, 6, 7 and 8) and their optimum growth was observed at neutral pH of 7.0. At this neutral pH, highest growth for B. licheniformis, O. intermedium and M. paludicola was obtainedafter 30, 34 and 36 h of incubation, respectively. After processing, in both WS and DL, highest and lowest gas production and organic matter (OM) digestibility were observed by B. licheniformis and control treatment, respectively (P Results of present study showed that optimum growth for Ochrobactrum intermedium and Microbacterium paludicola isolated from termite gut was observed at 37 oC while it was 40 oC for Bacillus licheniformis. Optimum pH for growth of all of isolates was 7. Processing wheat straw and date leaf with bacteria, especially B. licheniformis improved rumen fermentation parameters in vitro. Research for upgrading the nutritive value of by products with ligninolytic bacteria isolated from termite gut is in infancy. Thus, further works in this field of study is needed.

Varroa destructor is the most important ectoparasite of Apis mellifera. This review addresses the interactions between the varroa mite, its environment, and the honey bee host, mediated by an impressive number of cues and signals, including semiochemicals regulating crucial steps of the mite’s life cycle. Although mechanical stimuli, temperature, and humidity play an important role, chemical communication is the most important channel. Kairomones are used at all stages of the mite’s life cycle, and the exploitation of bees’ brood pheromones is particularly significant given these compounds function as primer and releaser signals that regulate the social organization of the honey bee colony. V. destructor is a major problem for apiculture and the search for novel control methods is an essential task for researchers. A detailed study of the ecological interactions of V. destructor is a prerequisite for creating strategies to sustainably manage the parasite.

The biological activity of probiotics is affected by various environmental factors each of which can influence the performance as well as the growth of probiotics for increasing the health of the consumers. The aim of is to investigate the effect of fructose , dose 0/5,1 ,1/5 and 2 present of the primary culture and temperature of 35 ,38 ,41 and 44 degrees centigrade on the growth and metabolism and metabolism of Lactobacillus acidophilus La5 in sterilized milk ; in order to do this ,the milk fermented with Lactobacillus acidophilus La5 (as the culture ferment ) was used for incubating the milk sample different; incubators were used as the suitable temperatures for the growth of microorganisms. The acidity and the pH of the milk samples were measured during different hours and the total number of microbial counts were and measured at 0 , 4 and 8 h after the incubation. In order to measure the effect of fructose 0/75 % (w/v) added the milk samples, and the resulted sample , together with the control sample , was kept in incubation at 41 degree centigrade ; and then the acidity , pH of Lactobacillus acidophilus La5 was measured and the total number of lactobacillus acidophilus was counted during the above mentioned periods after incubation . Every of above operations was replicate ten times ; then , utilizing statistical tests , were compared with one another during the above mentioned periods. The findings of the study indicated that the total number of bacteria and the amount of acidity in the incubated milk samples at 41 and 44 degrees centigrade were significantly greater than the other temperatures (P<0.05 ). The multiplication rate of the total hours of bacteria in samples containing 2 % of culture ferment during the fourth h of incubation was significantly greater than the other samples ( P<0.05 ); however , this difference in 8 h after the incubation was not significant. Concerning the use of prebiotic fructose, the total number of bacteria in and the acidity in the milk samples containing fructose was significantly greater than the number of control sample ( P<0.05 ). It is concluded from this study that The best alternative temperature for this purpose is an incubation temperature range of 41-44° C as well and if fructose is added to milk , there is a significant effect in enhancing the growth of Lactobacillus acidophilus La5.