Pterygoplichthys spp. (Siluriformes: Loricariidae) meal is suitable for the culture of Nile tilapia Oreochromis niloticus (Cichlidae) juveniles

ABSTRACT: We search for positive utility impact on the invasive species Pterygoplichthys spp. The optimal level of replacement of sardine meal (SM) by Pterygoplichthys spp. meal (PLM) in practical feeds for fry of Nile tilapia (Oreochromis niloticus) was evaluated. We evaluated six experimental diets: 50% PLM-50% SM, 60% PLM-40% SM, 70% PLM-30% SM, 80% PLM-20% SM, 90% PLM-10% SM and 100% PLM-0% SM. In a recirculation system, 270 sex-reversed tilapia fry were used (0.7 ± 0.1 g). Diets were administered in triplicate and the experiment lasted 56 days with sampling every 14 days. There were no statistical differences in growth. At the end of the experiment, the SGR, ADG, CF, WG, DFI, FCR and PER were determined without significant differences (P > 0.05) between treatments, but there was a tendency that could indicated higher WG and PER in the 90% PLM-10% SM treatment (93.56 ± 0.43% and 8.44 ± 1.18 g, respectively). All survival rates were higher than 90% with no significant differences. Additionally, there were no statistical differences in the chemical composition of the whole fish, while apparent digestibility coefficients of protein (81-90%) and lipids (87-93%) also showed no significant differences. We concluded that 100% PLM can replace 100% SM in feeding fry of O. niloticus without affecting their survival, growth or chemical composition or the apparent digestibility of nutrients.

Experimental Investigation on Filtration and Cooling Effect of Kitchen Hood Ventilation System from Water-Mist Recirculation Spray: Water-Mist Spray Cycle

A Water-mist spray system in several heavy-duty kitchen hood canopies is installed to efficiently control the high heat loads and grease emissions produced from the cooking process and for safety purposes. The main purpose of this study is to reduce water consumption by introducing the water-mist recirculation system to replace the current method water-mist system since it is working as water loss. A standard ASTM 2519 and UL 1046 full-scaled experiment is developed in the laboratory. An existing Halton Europe/Asian water-mist operating system is adopted in this study. Twelve (12) cycles (at 24 hours of water-mist activation) have been studied to determine the maximum water-mist activation cycle. The data are collected at two (2) hours water-mist activation at every water-mist recirculation cycle. The water-mist spray fluids viscosity is 0.7 cP from fresh water until the 4th cycle (8 hours water-mist spray) and increase 14.29% (0.8 cP) at the 5th cycle to the 12th cycle. On average, the difference in gas emissions percentage for CO concentration between fresh water until the 4th cycle is 10.81 – 18.92% while the CO2 concentration is 12.33 – 18.22%. On average, the difference in cooling effects percentage for ducting temperature between fresh water until the 4th cycle is 5.55% while the hood temperature is 2.33%. From the study, the water-mist recirculation system could save up to 611,667 litres per year and 466,798.5 litres per year water for all U.S, European, and Asian kitchen hood designs per hood length. By adopting the new water-mist recirculation system to the current water-mist kitchen hood, the water operational cost for water successfully reduced to RM 4,889.63 per year and RM 6,977.86 per year for U.S design and European or Asian design per hood length respectively. The water-mist recirculation system has great potential to improve the current water-mist system for the commercial kitchen hood.

Rational use environmentally friendly products of aquaculture

Aquaponics is a new agricultural industry with potential in Kazakhstan. It is the combined culture of fish and plants in a recycling aquaculture system. The plants use the nutrients from fish effluent for growth. Through environmentally sustainable technology, locally grown high value products can be produced and marketed year round. Aquaponics operations are inherently diversified operations as they offer two profit centres: fish and plants. Аquaponics facilities contain contains plant and fish components together in one recirculation system. The fish water, rich in nutrients, is used for plant growth, while the plants are used as biofilters for water regeneration.

Comparative evaluation of the biofloc system versus the recirculation system with Macrobrachium amazonicum / Avaliação comparativa do sistema bioflocos versus o sistema de recirculação com Macrobrachium amazonicum

The aim of this study was to evaluate the efficiency of the biofloc system versus the recirculation system using the native Amazonian freshwater shrimp Macrobrachium amazonicum (Heller, 1862) as a cultivation organism. In this initial evaluation, the water quality parameters of each system were measured and the survival rate in the biofloc system showed similar values for M. amazonicum grown in a super-intensive recirculation system with averages values of 60%. The results indicated that both systems were within acceptable limits in terms of parameters (physical-chemical) and the survival rate of both systems showed similar values for M. amazonicum.