فهرست مطالب d. alipour

Potato (Solanum tuberosum L.) is widely grown in different environments, forming the fourth largest crop in the world, with a production of almost 321 million metric tons. Seed potato degeneration, the reduction in yield or quality caused by an accumulation of pathogens and pests in planting material due to successive cycles of vegetative propagation, has been a long-standing production challenge for potato growers around the world. In developed countries this problem has been overcome by general access to and frequent use of the seed, produced by specialized growers, that has been certified to have pathogen and pest incidence below established thresholds, often referred to as certified seed. Potato leaf roll virus (PLRV) and potato virus Y (PVY) are the most important viruses infecting potato crops and also reduce the size as well as a number of potato tubers with annual global yield losses of up to 20 million tonnes. In Iran, PLRV and PVY are widely distributed in most potato-growing areas in Iran and have caused severe yield losses of up to 40 percent.This study was carried out to evaluate the amount of potato seed field’s infection to potato leaf roll virus and potato virus Y in different regions of Hamedan province and to survey the sensitivity of cultivars to studied viruses.

Leaf samples were prepared from potato seed field (S seed class) which has a 3-years rotation and 400 meters isolated distance from other potato growing fields. Studied potato seed fields were located in three regions of Hamedan province included: KaboodarAhang, Goltappe and Razan. These regions are the main potato production areas in Hamedan province of Iran. Leaf samples infection to potato leafroll virus and potato virus Y was determined by DAS-ELISA test using specific antiserum (Patho Screen Kit, supplied by Agdia Incorporated, USA) following the fundamental protocol outlined by Clark and Adams (1977) ELISA assay. The yield of all studied fields was determined after harvesting. Meteorological information of three seed production areas included average temperature, rainfall and wind speed was collected during the studied period.

Results showed that infected potato plants by both studied viruses (potato leaf roll virus and potato virus Y) were seen in KaboodarAhang region, while potato plants infected by studied viruses were not seen in the other regions (Goltappe and Razan). The probable cause of higher virus infection in KaboodarAhang region could be due to the wider migration of carriers and their greater activity in the region which had higher average temperature and rainfall than the other two studied areas. In Goltappe region which was diseases free, the temperature means and the amount of rainfall was lower than the other regions during the growth period. Maximum wind speed (25 m.s-1) in the infected region (KaboodarAhang) was higher than regions which were free of diseases (Goltappe and Razan). The wind blowing provides the possibility of transmission of viral infection by aphids (especially Myzus persicae) from neighbor infected fields.  However, portable flight capacity such as the aphid Myzus persicae may rarely exceed 100 meters, but Wind-assisted flight can carry aphids for several hundred kilometers. Therefore, what matters more than the isolated distance between potato seed production fields is the health of the seed production area and the speed and direction of the wind.Among studied cultivars, Agria and Arinda cvs. were infected by both studied viruses, while the other studied cultivars (Sante, Banba and jelly) were not infected.In Agria cv. and in the range of infection between 1 and 3%, the relationship between yield and potato plants infection to PLRV and PVY was not found, but in Arinda cv., the yield of virus (PLRV and PVY) free fields were much higher than those of infected by PLRV and PVY.

Since the Agria and Arinda cvs. were infected by potato leaf roll virus and potato virus Y, this can be concluded that these cultivars are sensitive to potato leafroll virus and potato virus Y. It seems Goltappe and Razan regions are suitable for potato seed production in Hamedan province. In the low range of viral infection, no logical relation was seen between potato plant’s yield and viral infection of plants. Among studied meteorological parameters, temperature mean and the amount of rainfall in the free of diseases region are lower than infected region.

Considering water and land limitation in agriculture, providing some year-round feedstuffs for livestock animals is a challenge for producers. Agro-industrial co-products, which are not in completion with human food resources, can be effectively consumed by ruminant species. Tomato waste (TW) is a by-product obtained after production of tomato sauce, paste and juices in manufactures. Using some physical and chemical processing of by-products can improve their nutritive value for feeding ruminants. Autoclave and exogenous fibrolytic enzymes are of those physical and chemical processing, which have been applied for several agro-industrial co-products. This study aimed to evaluate nutritive value, nutrient digestibilities and gas production parameters of chemically (autoclave and urea treating) and enzymatically (Natuzyme®) treated TW. Material and Fresh TW were sun-dried and were stored in cold temperature until the beginning of the experiments. Experimental treatments included: control (untreated), autoclaved (120 psi for 30 min), urea (3% urea added DM basis and anaerobically stored for 28 days in room temperature), and autoclave+urea (combination of previously mentioned treatments, 0. 5% enzyme and 1% enzyme). One day before the starting of experiment, aqueous solutions of enzymes were added to the samples. For the rest of experiments, samples were ground to pass 1 mm sieve size. Chemical composition of samples (i. e. , DM, NDF, ADF, CP and ash) was determined. For in vitro gas production tests (GP), the rumen fluid was taken from three ruminally fistulated Mehraban male mature lambs. For measuring kinetic parameters of gas production, 200 mg of samples were incubated in glass syringes containing 30 ml buffered-ruminal fluid for 144 hours. The cumulative produced gas was recorded at different times of incubation. The gas production data were fitted to exponential equation of GP= A (1-e-c(t-L) ); where GP is gas production at different times of incubation, A is asymptotic gas production (ml/200 mg DM), c is rate of gas production (/h), t is time of incubation and L is lag time (h). For measuring digestibility parameters, 500 mg of samples in glass syringes contained 40 ml buffered ruminal fluid were incubated at 39 °C for 24 hours. Volume of GP, metabolizable energy (ME), organic matter digestibility, partitioning factor (PF) and microbial biomass were determined after termination of incubation. All the in vitro gas production trials were carried out in three runs. Data were analyzed based on a completely randomized design using Proc GLM of SAS software. The differences among treatments were evaluated using Duncan's multiple range test. The highest amount of NDF, ADF and ash were observed in control treatment, while the highest CP was recorded with the treatment of 3% urea. The lower cell wall content in treated TW could be due to the role of urea and enzymes in breaking the links between cellulose and lignin. The treatment of 1% urea had the highest increment in comparison with control which is likely because of the activity of added enzymes in increasing fermentation of TW cell wall. The lower GP of 3% urea and autoclave+urea among all treatments can be due to the negative effect of ammonia on both direct GP from microorganisms activities and indirect GP from buffering of produced volatile fatty acids during fermentation. Also, the highest values of L were observed in 3% urea and autoclave+urea groups. The treatments were significantly different in dry matter  digestibility and OMD of which control had the lowest value. This could be due to the higher percentage of cell wall in control TW and the negative relation of cell wall with digestibility. The treatment of 1% enzyme and control showed the highest and lowest MB, respectively (P<0. 05). The higher MB in treated TW shows that processing had increased the availability of growth required factors for microorganisms. The PF were higher in urea, autoclave+urea and 1% enzyme groups (P<0. 05). The higher value for this parameter shows that degraded organic matter is more directed towards microbial biomass production rather than production of volatile fatty acids. The treatment of 1% enzyme had the highest value of ME, while control showed the lowest value (9. 57 vs. 9. 30 MJ/kg DM, respectively). Considering the obtained data related to dry matter digestibility, NDF, PF and chemical compositions of different treatments, it is concluded that the administration of 3% urea and using Natuzyme® at the level of 1% of DM improved the nutritive value of TW. Further research is needed to study the effect of using TW in performance of productive ruminants.

Sheep adapted to consume tannins rich feeds such as oak leaf (OL) appear to develop defensive mechanisms by their ruminal bacteria against these polyphenols. The capabilities of ruminal isolated tannins resistant bacteria from these animals to ferment a tanniniferous feed (i.e., pistachio hulls, (PH) which were incubated with rumen fluid from Holstein dairy cows was assessed. Six g positive cocci were isolated from the rumen of sheep and the 16s rRNA gene sequences showed them to be closely related to Streptococcus gallolyticus. In three runs of in vitro gas production (GP), the effect of two of the isolates incubated with bufferedruminal fluid of Holstein cow and PH was evaluated. The GP was recorded from 1 to 96 h of incubation. Incubating either of the isolates with PH caused a significantly higher in vitro gas production, estimated parameters, in vitro organic matter disappearance, metabolisable energy and volatile fatty acids than those without any isolate. The improvement in the ruminal parameters when either of the isolates was used suggested the possible presence of isolated tannins-resistant bacteria (Streptococcus gallolyticus sp.),however, in vivo studies must be conducted to confirm the in vitro results.

Rumen acidosis can be caused by overeating of readily fermentable carbohydrate, and as a result an imbalance may be seen in rumen microbial population. In order to characterization of lactate producing bacteria 30 isolates were collected from ruminal fluid of three male Mehraban sheep (receiving a diet containing 60% concentrate and 40% alfalfa hay) using specific cultural media. The isolates were evaluated based on gram staining, catalase activity, indole production test and their ability to ferment some sugars. Identification of isolates was undertaken using 16s rRNA gene sequences. A RFLP procedure was used to test the genetic homogeneity of isolates. Four isolates were selected and their 16s rRNA were sequenced. Based on information obtaind from Gene Bank, the isolates were closely (>99%) related to Streptococcus macedonicus, Streptococcus luteciae, Enterococcus faecalis and Escherichia fergusonii.

The aim of this study was to evaluate the effect of Ajowan essential oils (AEO) on rumen fermentation using in vitro gas production. Therefore, different doses of AEO (i.e., 0, 150, 300, 450 or 600 ppm) were added to the syringes of the gas production. A typical diet of growing lambs was used as fermentation substrate. At the first step, the gas production syringes were incubated for 144 hours to estimate kinetics of fermentation (i.e., asymptotic gas production, lag time and extent of dry matter degradation). At the second phase, concentration of total volatile fatty acids (TVFA), ammonia, microbial mass and true organic matter digestibility were determined. Inclusion of AEO decreased asymptotic gas production and extent of dry matter degradability. Using AEO at levels of 150 or 300 ppm enhanced microbial mass. Partitioning factor also increased in parallel with the increment of AEO level, whereas true organic matter digestibility declined. Overall, the result of this study showed the antimicrobial activity of AEO against rumen microorganisms. AEO has the potential for modulating rumen fermentation and further research is needed to assess its effect upon microbial biomass and profile of individual fatty acids at lower doses of inclusion.