Ernest Ross

Preliminary studies on the preparation and feeding of crustacean diets

Abstract An inexpensive, simple and effective method is described for preparing water-stable diets suitable for aquatic crustacean feeding experiments. Seven representative diets ranging from 25 to 40% total protein were prepared and tested for their dry weight loss in water for 1-, 3- and 5-hour periods. Dissolution was influenced by diet composition, and loss was greater in fresh water than in sea water. Diets were subsequently fed to both marine shrimp (Penaeus sp.) and fresh water Malaysian prawns (Macrobrachium rosenbergii) held under experimental conditions. Results of these trials showed that diets were capable of producing a 106–329% increase in weight in juvenile Penaeid shrimp over a 25-day period. Growth appeared to increase with amount of protein in the diet. Juvenile Malaysian prawns held under mass culture conditions for 60 days increased in length from 98 to 112% on three different diets. Juvenile Penaeus japonicus held under mass culture conditions for 75 days increased in weight 1877% on a 35% protein diet. In general, all prepared diets produced good growth with low mortality when compared with data reported by other workers.

Acute and subacute toxicity of insecticides to chicks

Abstract The effects of feeding insecticides on New Hampshire chicks were studied. The acute toxicity of 22 insecticides administered as single oral doses as well as the subacute toxicity of 16 insecticides given in the feed and 3 insecticides administered in the drinking water determined. Symptomatology, growth, and efficiency of feed utilization are discussed.

Acute and subacute toxicity of several organophosphorus insecticides to chicks

Abstract The acute and subacute toxicity to White Leghorn cockerels of 14 organophosphorus insecticides were studied. These included 2 phosphates, 8 phosphorothioates, 2 phosphorodithioates, a phosphoramidothioate, and a dithionopyrophosphate. Symptomatology, growth, and blood plasma cholinesterase activity are discussed.

Further studies on the acute and subacute toxicity of insecticides to chicks.

Abstract The acute and subacute toxicity to White Leghorn cockerels of 44 organic insecticides were studied. These included 6 phosphates, 6 phosphorothionates, 2 phosphorothiolates, 10 phosphorodithioates, a phosphorotrithioate, 3 phosphonothioates, 3 phosphonodithioates, 2 phosphonotrithioates, 9 carbamates, a carbonate, and a chlorinated hydrocarbon. Symptomology, growth, and blood plasma cholinesterase activity are presented.

Changes in dimensions and mechanical properties of bone in chicks fed high levels of niacin

Tibia dimensions and mechanical properties were determined in White Leghorn cockerels that had been fed from 0.1 to 2.0% niacin as a supplement to standard poultry diets. Four experiments of from 20 to 38 days were conducted. No significant differences due to niacin were found in weight gain, feed consumed or feed:gain ratios. Decreases in the exterior (P < 0.009) and interior (P < 0.015) diameters of the major axes of the tibiae were found at 0.75-2.0% niacin. Exterior (P < 0.005) and interior (P < 0.001) diameters of the minor axes of the tibia were decreased at levels of 0.75 and 1%. Changes occurred in lateral wall thickness of chicks fed 0.75% niacin for 20 days (P < 0.004) and 38 days (P < 0.023) and in anterior wall thickness of 6-month-old chickens fed 1.0% niacin for 28 days (P < 0.001). Ultimate force was decreased in young chicks fed 1.0 and 1.5% niacin (P < 0.014) and 6-month-old White Leghorn chickens fed 1.0% niacin (P < 0.004). The addition of high levels of niacin to chick rations resulted in changes in dimensions, bone strength and susceptibility to fracture.

Acute and subacute toxicity of several insecticides to chicks

The acute oral LD50s of 12 insecticides for male White Leghorn cockerels are presented, together with estimates of the dietary concentrations causing 50% inhibition of plasma cholinesterase at the end of 1 week of feeding.