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S. G. Hughes

Publications and source records attributed to S. G. Hughes.

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↗
USGS2003

Phosphorous digestibility and activity of intestinal phytase in hybrid tilapia, Oreochromis niloticus X O. aureus

Experiments were conducted to determine the degree to which phytate-bound phosphorus from plant protein sources could be used by hybrid tilapia (Oreochromis niloticus X O. aureus). Utilizing an inert marker technique with chromic oxide, hybrid tilapia in our study were effective at utilizing both inorganic and phytate phosphorus as evidenced by average apparent digestibility values of 93.2% and 90.0% for total and phytate phosphorus, respectively. Analysis of the intestinal brush border membrane of the tilapia revealed enzyme activity that was capable of hydrolyzing phytic acid. The presence of phytic acid hydrolyzing enzyme activity in the intestinal brush border provides a probable mechanism by which these hybrid tilapia are able to utilize phytate phosphorus effectively. ?? 2003 by The Haworth Press, Inc. All rights reserved.

Journal of Applied Aquaculture↗
USGS1995

Protein retention and liver aminotransferase activities in Atlantic salmon fed diets containing different energy sources

Atlantic salmon ( Salmo salar ) fingerlings (14.4 g) were fed diets containing either glucose, dextrin, raw corn starch and lipid, or a high protein U.S. Fish and Wildlife Service open-formula diet (ASD2-30) for 12 weeks. Significant differences in weight gain and feed: gain ratio were not observed among salmon fed the diets containing glucose, dextrin or ASD2-30. Diets containing dextrin and glucose supported greater protein retention and reduction in alanine aminotransferase activity than the other diets. Activity of aspartate aminotransferase was not affected by the dietary treatment. Protein retention correlated highly with alanine aminotransferase activity.

Comparative Biochemistry and Physiology, Part A: P↗
USGS1993

Effects of feeding a high level of D-glucose on liver function juvenile white sturgeon (Acipenser transmontanus)

Juvenile white sturgeon ( Acipenser transmontanus ) were fed three isonitrogenous and isoenergetic diets containing either 35% D-glucose (HC), a mixture of 20% dextrin and 10% cellulose (MC), or 23% cellulose (LC), to investigate the effects of dietary carbohydrate on liver function. After 8-week feeding, body weight gain of fish fed the HC diet was consistently higher than that of fish fed the MC and LC diets, but was not significantly different from the MC-fed fish. Fish fed the HC diet had significantly (p < 0.05) higher feed efficiencies and liver glycogen concentrations than fish fed the MC and LC diets. Sturgeon were injected intravenously with 10 mg kg -1 body weight of sulfobromophthalein (BSP) and post-injection blood taken from the caudal vein at 15, 30, 60, and 120 min. No significant differences in plasma BSP concentrations were found among the treatments at these times. Plasma hemoglobin and activities of aspartate and alanine aminotransferase were not affected by the diets. This study suggests that the HC diet does not adversely affect liver function or weight gain. Inclusion of high dietary levels of digestible and inexpensive carbohydrates in commercial sturgeon feeds seems promising, but long-term feeding trials should be conducted to confirm this assertion.

Fish Physiology and Biochemistry↗
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

Single-feeding response of chinook salmon fry to potential feed intake modifiers

A study was conducted to determine the effects of various potential feed intake modifiers on initial feed consumption by spring chinook salmon ( Oncorhynchus tshawytscha ). Feed intake was immediately and significantly influenced when glycine, trimethylamine, or betaine was added to experimental diets. Results support the notion that glycine enhances feed intake, whereas trimethylamine and betaine decrease it. The reduced consumption of diets containing betaine, which has often been described as a feeding attractant, may have been a response to the chemical form of this compound used in this study (betaine hydrochloride) and may not occur if the free form of betaine is used.

Progressive Fish-Culturist↗
USGS1992

Development of a practical diet for juvenile striped bass

We formulated four diets that simulated the amino acid profiles of eggs of striped bass Morone saxatilis , carcasses of larval striped bass, eggs of rainbow trout Oncorhynchus mykiss , or nauplii of Artemia salina ; a fifth diet contained a high concentration (33.6%) of shrimp meal. These diets were fed to juvenile striped bass for 14 weeks. Striped bass grew best when fed diets with an amino acid pattern that simulated the patterns of rainbow trout eggs or Artemia salina . Fish fed these two diets grew as well as, and had carcass compositions and protein efficiency ratios similar to those of, control fish fed the federally specified ASD2‐30 salmon diet. No histological or morphological abnormalities were noted. These two diets, which have potentially lower production costs and contain slightly less protein than ASD2‐30, may be used as prototype diets specifically for striped bass. Through further minor refinements, the diets could be used in production hatcheries.

Transactions of the American Fisheries Society↗
USGS1991

Use of lupflour as a replacement for full-fat soy diets for rainbow trout (Oncorhynchus mykiss)

A 12-week feeding study was conducted to determine if either whole or dehulled lupin flour could be used as an economical replacement for full-fat soybean meal (FFSM) in a ration for rainbow trout ( Oncorhynchus mykiss ) and to determine if it was necessary to replace the soybean oil lost when FFSM was omitted from the ration. The results of the trial indicated that lupin can be used as a substitute for FFSM without the soy oil supplements used in a previous study. Total percentage weight gains of fish fed the diets containing soy, lupin, or lupin with added oil for 12 weeks all fell within the range 170–180. In addition, in fish fed the diets containing the higher-protein lupin, growth was at least equal to and up to 15% greater than that shown by the fish fed the soy diets. This interpretation of the data would indicate that the economics of using lupin (at the quoted prices) favors its use over FFSM in the test ration and that the dehulled (higher-protein) lupin may be even more desirable for use in feeds for salmonids.

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↗
USGS1991

Response of first-feeding spring chinook salmon to four potential chemical modifiers of feed intake

The feed intake of first‐feeding spring chinook salmon ( Oncorhynchus tshawytscha ) changed significantly when the amino acid glycine or the ammonium‐containing trimethylamine was added to experimental diets in a 2‐week feeding trial. Glycine enhanced feed consumption, whereas trimethylamine (which occurs in rancid fish meals and oils) decreased it. This effect of trimethylamine may indicate that the fish were sensitive to it as an indicator of the freshness of their feed; this possible sensitivity may play a role in the apparent aversion that salmonids and other fish show toward highly oxidized meals and oils.

Progressive Fish-Culturist↗
USGS1990

Use of triticale as a replacement for wheat middlings in diets for Atlantic salmon

A study was conducted to determine the value of triticale (a hybrid between rye and wheat) as a substitute for wheat middlings in the diet of Atlantic salmon ( Salmo salar ). Data on growth and carcass composition of fish fed the experimental diets containing triticale were comparable to those of fish fed the control diet with wheat middlings. No differences in diet acceptability were apparent when triticale was substituted for wheat middlings in the basal ration. Though the effect of triticale substitution on pellet quality (i.e., durability) is not known, the results indicated that this hybrid grain can be used as a nutritional substitute for wheat middlings in the diet of salmonids, and that further evaluation of this potential feed ingredient is warranted.

Aquaculture↗