Controlled-environment System Research Articles

THE PROTEIN REQUIREMENT OF PENAEID SHRIMP AT VARIOUS LIFE‐CYCLE STAGES IN CONTROLLED ENVIRONMENT SYSTEMS

ABSTRACTInvestigations into the nutrient requirements of penaeid shrimp in controlled environment systems using extruded diets compounded from practical ingredients have shown that the protein requirement of the early postlarval animal exceeds 40% crude protein, but decreases to less than 30% crude protein in the later life‐cycle stages. Studies of the importance of protein quality, i.e., source and amino acid balance, indicate that when marine protein sources, e.g., fish meal and shrimp meal, exceed 40% of the finished ration performance of the animal suffers. The improbability of lysine and methionine being limiting amino acids in practical rations is discussed.In addition, the protein requirements of the Gulf of California brown shrimp, (Penaeus californiensis) is compared to non‐grooved shrimp, Penaeus stylirostris and Penaeus vannamei.

The influence of blue- and red-biased light spectra on the growth and development of plants

The various lighting systems used for studies of plant growth in controlled environment systems differ markedly in the proportions of blue and red waveband light emitted in the visible spectrum depending both on the types of lamp chosen and on the proportions of each lamp type used. A series of new high intensity lamp systems, which provided wide variations in blue/red waveband ratios were used in these studies to test at different irradiance levels, the effects of these different light spectra on the growth of four plant species ( Sorghum bicolor L., Glycine max L., Lolium perenne L., and Trifolium repens L.). The biased spectral treatments used, resulted in marked differences in dry-matter accumulation, affected the relative proportions of leaves and stems and influenced tiller and secondary stem development. For example, final shoot dry-weight and plant height were increased approximately two-fold and leaf area was increased by 46% with sorghum under the red-biased compared with blue-biased conditions at the low irradiance level tested. Blue-biased conditions also enhanced the concentrations of amino acids (particularly aspartic and glutamic acids) and protein whereas, in contrast, red-biased sources increased the concentrations of soluble sugars and starch in the leaf tissue. The implications of these results to controlled environment studies are discussed.

Engineering Aspects of Bivalve Molluscan Mariculture: Culture System Configurations

ABSTRACTThe University of Delaware Mariculture Project is working toward development of commercial, closed‐cycle, controlled environment shellfish mariculture. Thus far, three principal controlled environment system configurations have been designed and utilized. Each of these systems served a specific purpose.The technical feasibility of raising bivalve mollusks from egg to market size in a recirculating system with a diet of cultured algae has been demonstrated. Currently system optimization and cost reduction efforts are working toward achievement of an economically feasible system. Each of the principal system configurations is described and the essential differences among them discussed.

Controlled environment systems for experimental animals. II. A unidirectional air flow tent.

A horizontally ventilated tent for housing pathogen-free experimental animals in racks of conventional cages is described. Heating and refrigeration units may be incorporated without structural modification.

Controlled environment systems for experimental animals. I. A unidirectional air flow brooder for chicks.

A hot-air, 2-tier brooder has been designed for rearing and experimental work with 100 pathogen-free chicks up to the age of 3 weeks. It provides a high degree of protection against infection without having to resort to the inconvenience of isolator techniques. Filtered air is supplied horizontally at a constant velocity of 0.51 m/sec (100 ft/min). Temperature can be varied from ambient to 35°C (95°F) and can be controlled to within 0.5°C (1°F). In it chicks grew faster and more uniformly than in a conventional hot-panel brooder.

Evidence of a possible requirement for nickel by the chick.

SummaryAfter 3 weeks on a dried skim milk-corn meal-based low-nickel diet (<0.08 ppm Ni), chicks which were maintained in an all-plastic controlled environment system had the following symptoms: (1) a change in leg pigmentation; (2) thickening of the long bones; (3) swelling of the hock joint; and (4) a significantly reduced length:width ratio of the tibia. All symptoms were prevented by the supplementation of 5 ppm nickel to the diet. Also, chicks fed the low-nickel diet accumulated a significantly greater amount of 63Ni in the liver, spleen, aorta, and possibly bone during the 6 hr after oral dosage than did control birds. This evidence supports the hypothesis that nickel has a physiological role in the chick.

A Controlled Environment System for New Trace Element Deficiencies

An all-plastic, controlled environment system is described for animals such as rats. The system, consisting of an air filter assembly, isolator, caging, and accessories, minimizes extraneous trace element contamination. The isolator, a modification of germfree isolator models, can hold 25 rats in groups of 5/cage. Weanling rats fed laboratory ration in the controlled, but not germfree, environment grew as well as control animals maintained outside of the isolator in metal cages under conventional conditions. A new trace element deficiency was observed in rats fed amino acid diets supplemented with the known required trace elements inside the controlled environment. Inhibition of growth, seborrhea, and pronounced alopecia developed within 1 to 3 weeks. Death occurred within 2 to 6 weeks. Conventional outside controls fed the same diet grew more rapidly and showed no deficiency symptoms. Supplementation of 0.4% yeast ash prevented the deficiency symptoms and improved growth. The results indicate that the amino acid diet lacks unidentified inorganic trace factors which are supplied by the environment under conventional conditions of animal experimentation. The described technique coupled with modern, sensitive methods of analysis permits rigorous and definitive experiments on the essentiality of specific trace elements.

A controlled environment system for study of mammalian cell physiology.

A controlled environment system for study of mammalian cell physiology.

An Environment System for Plant Studies with Controlled Temperature, Humidity, and Light

NTEED for reliable information concerning the effects of environN5 ment on the response of plants to herbicides motivated the construction of the controlled environment system described herein. A unit suitable for such studies should have these general specifications: 1. a useful range of control of light, temperature, and relative humidity; 2. no recirculation of air, to avoid overall contamination of the unit by volatile herbicides; 3. capability of maintaining several sets of conditions simultaneously; and 4. a design which may be modified easily. The system described was constructed with these points in mind. A schematic diagram illustrates the major structural components of the environment system (Figure 1). Outside air enters the cooling

Preliminary Design Investigation of Controlled Environment Systems for Air Pollution Studies

Preliminary Design Investigation of Controlled Environment Systems for Air Pollution Studies