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Geology topics

S. G. Hughes

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

At least 19 recordsLinked to original sources
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

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↗
USGS1988

Assessment of lupin flour as a diet ingredient for rainbow trout (Salmo gairdneri)

Studies were conducted to determine the value of lupin flour as a replacement for full-fat soybean meal (FFSM) in the diet of rainbow trout ( Salmo gairdneri ). Energy and digestibility values for lupin were determined using a metabolism chamber and it was found that trout utilize lupin well. The gross energy, metabolizable energy, and the percent digestibilities of protein and energy for lupin were found to be 4757 kcal/kg, 2797 kcal/kg, 85.2%, and 66.1%, respectively. When plant protein (either FFSM or lupin flour) was used as a supplemental dietary protein source to fish meal, or when the plant protein was the primary dietary protein source, fish fed diets where lupin completely replaced FFSM gained 99–106% of the weight of those fed the FFSM and had statistically equal feed efficiency ratios ranging from 80 to 83%. Although some minor dietary alterations may be needed (e.g., lowering the fat content of the diet) to maintain the economic advantage of lupin over soybean meal, lupin appears to be a useful source of protein for trout and may represent another economical plant protein alternative to fish meal.

Aquaculture↗
USGS1988

Effect of dietary propylene glycol on growth, survival, histology, and carcass composition of Atlantic salmon

Atlantic salmon ( Salmo salar ) were fed diets containing 0, 5, 10, 15, or 25% propylene glycol (a compound used to maintain high dietary moisture levels) to determine beneficial or detrimental effects. Weight gain and feed conversion efficiency were better for fish fed the diets containing 5–15% propylene glycol than in those fed diets containing either 0 (control) or 25% propylene glycol. No histological aberrations were noted in fish from any treatment. These results indicate that propylene glycol can effectively be used to elevate moisture level in diets for Atlantic salmon and may enhance diet palatability by improving texture, flavor, or moisture content.

Progressive Fish-Culturist↗
USGS1984

Effects of dietary excesses of branched-chain amino acids on the metabolism and tissue composition of lake trout ( Salvelinus namaycush )

1. Excesses of either leucine, isoleucine or valine were fed in separate experiments to determine if the branched-chain amino acid antagonism reported in other animals occur in trout ( Salvelinus namaycush ). 2. Parameters measured include growth rate, feed utilization efficiency, plasma and muscle-free amino acids, carcass composition and branched-chain amino acid aminotransferase. 3. Dietary excesses of leucine or isoleucine caused an increase in the valine requirement. 4. The inability of leucine and isoleucine supplementations to ameliorate the effects of excess dietary valine are interpreted as a valine toxicity rather than an antagonism.

Comparative Biochemistry and Physiology, Part A: P↗