Geology Reports⌕ Search

Geology topics

G. L. Rumsey

Publications and source records attributed to G. L. Rumsey.

At least 19 recordsLinked to original sources
USGS2007

Use of dietary yeast Saccharomyces cerevisiae nitrogen by lake trout

In a 12 week experiment, lake trout ( Salvelinus namaycush ) were fed diets in which 50% of the nitrogen was provided by one of six preparations of Saccharomyces yeast. Fish fed baker's yeast with disrupted cell walls grew at a rate equal to that of fish fed the control diet and faster than fish fed intact yeast cells. Fish fed a diet containing disrupted yeast cells previously washed in a saline solution did not perform as well. The results of this study indicated that it may be possible to use more than 50% yeast in the diets of salmonid fishes.

Journal of the World Aquaculture Society↗
USGS1994

History of early diet development in fish culture, 1000 B.C. to A.D. 1955

This paper traces the observations and speculations of early fish culturists as they sought to define the feeds necessary to keep hatchery fish alive. Although prescientific ideas about feeding fish existed in Egypt and China over three millennia ago, it was not until the 1700s that scientific studies of feeding and digestion by fish were documented. Aside from several books that provided early anecdotal accounts of feeds and feeding, much of the technical literature up to the 1930s is found in a few journals and relatively obscure bulletins. Such was the state of knowledge regarding the feeding of fish until about 1927 when Clive McCay, a professor at Yale University, and Abram Tunison, a hatchery worker, began some part‐time research on the nutritional requirements of trout at Connecticut's Burlington Fish Hatchery. In June 1932, these men founded an experimental hatchery, designed to study the nutrition, feeds, and feeding of fish, at Cortland, New York; this hatchery was operated under the auspices of the federal Bureau of Fisheries, the Conservation Department of New York State, and Cornell University. Over the next 25 years, it was research from this hatchery as well as from other federal, state, and university facilities that led to the development of purified test diets and the identification of the (unknown) growth factors in fresh meat, both essential criteria for scientific diet formulation, The first nutritionally complete diets appeared about 1955.

Progressive Fish-Culturist↗
USGS1993

Chemical and nutritional evaluation of soya protein preparations as primary nitrogen sources for rainbow trout (Oncorhynchus mykiss)

Five soya-bean preparations that had been subjected to various physicochemical processing procedures were chemically defined in respect to proximate analysis, amino acid analyses, protease inhibitor activity, soluble oligosaccharides and antigenicity. These soya preparations were then formulated, along with a low-temperature fish meal control, into six isonitrogenous and isocaloric experimental diets. The diets were fed to rainbow trout ( Oncorhynchus mykiss ) in feeding trials as well as in tests using specially constructed metabolic chambers. Based on the chemical and biological results, we concluded that soya-bean oligosaccharides do not have to be removed or modified for maximum growth or nitrogen utilization by rainbow trout. Likewise, the protease or trypsin inhibitor activity, which was low for all experimental treatments, did not appear to be a major factor in determining fish performance. Although the results regarding naturally occurring soya antigens only suggested allergenicity, it is concluded that more attention should be focused on these heat-stable proteins with antigenic or allergenic potential in fish diets.

Animal Feed Science and Technology↗
USGS1993

Fish meal and alternate sources of protein in fish feeds: Update 1993

Close to 12% of the world's 6.5 million metric tons of fish meal is used for aquaculture feeds. If current trends continue, roughly 20% to 25% of total world fish meal production could be used for aquaculture by the year 2000. Fish stocks used in fish meal reduction, however, appear to be in worldwide decline. A growing fish farming industry and a stagnating, if not diminishing, supply of fish meal have sobering economic and technologic implications for fish culture. Unless suitable alternate protein sources are found or other animal feeds begin to rely less on fish meal, fish production costs can be expected to increase dramatically. A precedent was set by the poultry industry, the most economically successful and competitive of the animal agriculture industries. Twenty years ago, the poultry industry consumed up to 80% of fish meal supplies. Through deliberate and well-organized research into alternate protein sources, the industry now uses less than 40% of supplies, and the trend is toward complete independence from fish meal. A comparable research effort is needed for aquaculture. Considering the biotechnologies available, plant proteins, processed to remove enzyme inhibitors and other antinutritional factors and properly supplemented with essential amino acids and minerals where needed, could produce results at least equivalent to those obtained with fish meal.

Fisheries↗
USGS1992

Nutritional value of dietary nucleic acids and purine bases to rainbow trout (Oncorhynchus mykiss)

Rainbow trout were fed diets with graded levels (0.6%, 1.6%, 2.5%, and 4.1%) of a yeast nucleic acid extract corresponding to dietary Saccharomyces cerevisiae levels of 7.5%, 20%, 30% and 50% or diets supplemented isonitrogenously (0.8% N) with free purines (adenine, guanine, xanthine, and hypoxanthine) in two 12-week studies. Fish fed increasing levels of yeast extract manifested significant ( P < 0.05) corresponding incremental increases in growth and nitrogen retention. No negative effects on feed intake were observed. When fish were fed supplemental free purines, adenine was shown to be a potent inhibitor of feed intake and growth. While supplementation with the remaining purines did not negatively affect feed intake or growth, carcass nitrogen retention was significantly depressed, indicating the lack of a nitrogen-sparing effect. Our results indicate that the nutritional significance of free dietary adenine versus nucleic acid-bound adenine in yeast or yeast nucleic acid is an important consideration in evaluating the suitability of single cell proteins in fish feed formulations.

Aquaculture↗
USGS1991

Choline-betaine requirements of rainbow trout (Oncorhynchus mykiss)

A series of experiments with rainbow trout ( Oncorhynchus mykiss ) were conducted to quantify the dietary requirement for choline as well as to determine whether betaine or methionine could spare the trout's choline requirement. Fish weighing 1.4 and 3.2 g, which were acclimated to a choline-deficient semipurified diet for 14 days before the start of the experiments, were shown to have a choline requirement of 813 and 714 ppm, respectively. When an excess of betaine was added to the choline-deficient basal diet, the choline requirement was reduced to about 400 ppm. These results suggest that about half of the trout's choline requirement must be met by choline itself, whereas the other half can be supplied by betaine. However, the requirement for choline itself must first be met before a response to betaine can be obtained. The addition of betaine to a choline-deficient diet resulted in no improvement in weight gain. Likewise, the addition of L-methionine, isomethyl to 1000 ppm choline, was without effect on growth in a basal diet marginally adequate in sulfur amino acids — suggesting that the trout's requirement for choline is not replaceable by methionine. Because the effects of dietary choline on liver lipid were variable and difficult to interpret, it was demonstrated that growth was more sensitive than liver lipid as an indicator of choline status.

Aquaculture↗
USGS1991

Effect of high dietary concentrations of brewer's dried yeast on growth performance and liver uricase in rainbow trout (Oncorhynchus mykiss)

The potential of using yeast nitrogen in fish feeds to replace proteins from conventional sources is an attractive option to nutritionists, feed manufacturers and fish farmers. Experiments were conducted to determine the effects of high dietary levels of brewer's dried yeast, with 20% of its protein represented by nucleic acid nitrogen, on the growth, feed conversion efficiency and uric acid metabolism of rainbow trout ( Oncorhynchus mykiss ). Growth and liver uricase activities were monitored in trout fed diets containing 0, 25, 50 or 75% yeast. Growth was faster and feed conversion more efficient in fish fed diets consisting of 25% yeast; the diets containing 50 and 75% yeast were seemingly unpalatable to trout. Liver uricase activity, present in all fish, was directly correlated with the dietary level of nucleic acids. It was concluded that although feed intake was depressed at yeast levels greater than 25%, the fish did not appear to be adversely affected physiologically by high dietary levels of nucleic acid nitrogen.

Animal Feed Science and Technology↗
USGS1991

Digestibility and energy values of intact, disrupted and extracts from brewer's dried yeast fed to rainbow trout (Oncorhynchus mykiss)

Although fish meal has historically been used as the primary source of protein in fish feeds, brewer's dried yeast (BDY) is presently being investigated as a primary replacement for fish meal. As little is known about the ability of fish to utilize BDY, studies were conducted to study bioavailability of intact BDY as well as several fractions derived from the disrupted yeast to rainbow trout. Dried BDY was fed to rainbow trout and digestibility and energy values were determined. When the yeast cells were fully disrupted, the absorption of nitrogen increased by more than 20% and the metabolizable energy of the yeast by more than 10%. Energy and nitrogen digestibility were further increased after the removal of all wall material and separation of nitrogen into amino acid and nucleic acid fractions. Disruption of the cell wall significantly increased the nutritional value of BDY for salmonid fishes. The findings suggest that further research be conducted on the use and economy of BDY as a primary nitrogen source in fish feeds.

Animal Feed Science and Technology↗
USGS1990

Effects of dietary a-linolenic acid on n-3 fatty acids of rainbow trout lipids

The effects of α-linolenic acid enriched diets on the lipid composition of rainbow trout ( Oncorhynchus mykiss ) muscle and liver were determined. Diets containing 0, 4, 10 or 20% (wt/wt) linseed oil were fed to 280 trout for up to 64 days. Linolenic acid levels in total lipid, neutral lipid and phospholipid of liver and muscle increased with duration of intake. The linolenic acid content of total lipid in muscle increased from 10 mg to 355 mg/100 g flesh. There was no significant increase in the elongated desaturated products, i.e., eicosapentaenoic or docosahexaenoic acids, in either tissue during the feeding period.

Lipids↗