Afshin Javadi and Seyed Amin Khatibi
The purpose of this study was to investigate the effect of a dietary probiotic on the growth performance and survival rate of Litopenaeus vannamei shrimp. Furthermore, the…
Abstract
Purpose
The purpose of this study was to investigate the effect of a dietary probiotic on the growth performance and survival rate of Litopenaeus vannamei shrimp. Furthermore, the microbial quality of shrimp was evaluated.
Design/methodology/approach
Shrimp were divided into treatment and control groups (each group containing 45 shrimp). They were fed for four weeks with a control diet alone or supplemented with a commercial probiotic (Protexin®). At the end of the trial, they were assessed for survival rate, weight gain, average daily gain and specific growth rate. Samples of tail meat were also provided aseptically from peeled shrimp for bacteriological analysis including the count of Staphylococcus aureus, enterococci, Clostridium perfringens, fecal coliform, Salmonella, Escherichia coli, Listeria monocytogenes and total bacterial count.
Findings
The growth performance of the probiotic-treated group significantly (p < 0.05) increased at the end of the experimental period. However, no significant differences were observed for the survival rate between the groups (p > 0.05). The count of C. perfringens and the total bacterial count in shrimp supplemented with the probiotic were significantly lower than those of controls (p < 0.05). The count of coliforms and S. aureus was not significantly different between the groups (p > 0.05).
Originality/value
It could be concluded that the probiotic bacteria have the potential to stimulate the growth performance of L. vannamei. They can also be used for biological control of food-borne pathogens and improve the microbial quality and safety of shrimp at the farm level.
Mohsen Babaei, Afshin Shariat-Mohaymany, Nariman Nikoo and Ahmad-Reza Ghaffari
One of the problems in post-earthquake disaster management in developing countries, such as Iran, is the prediction of the residual network available for disaster relief…
Abstract
Purpose
One of the problems in post-earthquake disaster management in developing countries, such as Iran, is the prediction of the residual network available for disaster relief operations. Therefore, it is important to use methods that are executable in such countries given the limited amount of accurate data. The purpose of this paper is to present a multi-objective model that seeks to determine the set of roads of a transportation network that should preserve its role in carrying out disaster relief operations (i.e. known as “emergency road network” (ERN)) in the aftermath of earthquakes.
Design/methodology/approach
In this paper, the total travel time of emergency trips, the total length of network and the provision of coverage to the emergency demand/supply points have been incorporated as three important metrics of ERN into a multi-objective mixed integer linear programming model. The proposed model has been solved by adopting the e-constraint method.
Findings
The results of applying the model to Tehran’s highway network indicated that the least possible length for the emergency transportation network is about half the total length of its major roads (freeways and major arterials).
Practical implications
Gathering detailed data about origin-destination pair of emergency trips and network characteristics have a direct effect on designing a suitable emergency network in pre-disaster phase.
Originality/value
To become solvable in a reasonable time, especially in large-scale cases, the problem has been modeled based on a decomposing technique. The model has been solved successfully for the emergency roads of Tehran within about 10 min of CPU time.