Effects of sowing methods and potassium application on the performance of two Alfalfa cultivars (Medicago sativa L.)

The aim of this study was to determine the feasibility of using irradiation technique (Gamma ray)-Cobalt-60 on destroying Salmonella in fish meal. The study consisted of 4 stages:-The first stage: included the isolation of Salmonella from locally produced fish meal in order to be used in this study. The second stage; Samples of sardine meal and tuna meal were contaminated with 3 different levels of active cells of Salmonella in test tubes (1013, 105, 107, cell/gram), respectively. They were then irradiated with dose 1, 2, 3, 4 kGy of gamma rays. After that the number of Salmonella cells resistant to radiation were counted for each treatment and the optimum dose that gave a 100% kill of salmonella was determined. The third stage: In order to fined if the optimum dose (3 kGy) which was obtained on laboratory scale in stage 2 is sufficient for destroying Salmonella cells in commercial packages of fish meal. A commercial samples of sardine meal weighing 25 Kg each were contaminated with 103, 105, and 107 cell/gram of active salmonella and exposed to irradiation dose of 3 kGy and 4 kGy of gamma rays. The number of surviving cells were determined and the optimum dose was found. The fourth stage: biological evaluation of sardine meal irradiated with 4 kGy was carried out. The irradiated sardine meal was added to a broiler finisher ration to raise the protein content to 24%. This ration was fed to one week old chicks for a period of 5 weeks and were compared to a control (chicks fed with ration to which non irradiated meal was added to raise the protein level to 24%). Data for birds feed consumption, weight gain, feed conversion ratio and mortality were monitored during the experiment. At the end of the experiment samples of chicken were dissected for veterinary examination. Results from first stage indicated that 33% of samples were found contaminated with Salmonella. A direct relationship was observed between the percentage of Salmonella death and radiation dose, as the level of salmonella contamination increased, a higher dose was required for the destruction of Salmonella. It was also found that the effectiveness of radiation dose varies with the type of fish meal. A significant difference was obtained between the chemical composition of Sardine meal and Tuna meal. Mean while a non significant effect of radiation on chemical composition was obtained. Results from the third stage showed that the 3 KGy dose in not sufficient for destroying salmonella cells in commercial bags of fish meal and a 4 kGy is the needed dose to a achieve a 100% destruction of salmonella cells. from the biological evaluation of fish meals treated with 4 kGy, it was found that there was no significant effect of radiation on feed consumption, weight gain, feed conversion ratio on compare with the control. In addition to that no mortality was recorder in both treatment. The veterinary examination showed no abnormal effects or cases in birds that were given the feed contained the irradiated fish meal. (author)