- Interactive effects between vitamins C and E on performance
of juvenile golden shiners Notemigonus crysoleucas fed
purified diets.
Rebecca Lochmann and Harold Phillips
A feeding trial was conducted in a flow-through system to
investigate the interactive effects of dietary vitamins C and E on
growth and health of juvenile golden shiners Notemigonus
crysoleucas in aquaria. Triplicate groups of 30 uniform fish
initially averaging 0.79 g were fed eight purified diets
supplemented with 23, 43, 98, or 222 mg of AA
(L-ascorbyl-2-monophosphate=Vitamin C) and either 0 or 38 mg of
DL-α-tocopherol acetate (αTA=Vitamin E) using a 4x2 factorial
design. Fish were raised in 110-L aquaria using dechlorinated
municipal water with a water temperature of 27 ± 2 C, and fed
twice daily to apparent satiation for 19 weeks. The average
individual weight gain and survival in the groups fed the
αTA-unsupplemented diets were lower than those of the groups fed
the αTA-supplemented diets at 19 and 14 weeks, respectively. The
effects were most pronounced in fish fed the αTA-unsupplemented
diet with 23 mg of AA/kg. Fish fed the αTA-unsupplemented diets
began to show vitamin-E-deficiency signs including muscular
dystrophy characterized by flesh loss on the dorsum, dermal
melanization, anemia, exudative diathesis, external hemorrhaging,
and elevated whole-body moisture after 10 weeks. Many muscle
fibers were atrophic and necrotic, and surrounded by various
mononuclear cells in connective tissues. Elevated dietary AA
increased total ascorbic acid (TAA) and dehydroascorbic acid (DHA)
concentrations in visceral tissues. Fish fed the
αTA-unsupplemented diets had very low α-tocopherol content in
viscera, and reduced whole-body total lipid and dry matter,
hematocrit, hemoglobin, lymphocyte percentage, alternative
complement activity (ACH50), and survival following exposure to a
stressful water temperature (37 C). The percentage of
thrombocytes and other leucocytes (dominated by neutrophils) were
relatively higher, and mean corpuscular hemoglobin concentration (MCHC)
was not different among treatments. The ACH 50 increased in the
groups of fish fed the αTA-supplemented diets with increasing
dietary AA levels to 98 mg/kg and leveled off between 98 and 222
mg/kg.
A sparing effect of vitamin E on vitamin C was found in fish fed
the αTA-unsupplemented diets. Regardless of αTA level, different
levels of dietary AA did not influence α-tocopherol content in
viscera. Elevated dietary AA reduced the incidence and severity of
vitamin-E-deficiency signs in a dose-dependent manner, as seen
from growth (after 19 weeks), percentage of melanized fish,
hematology, whole-body moisture, and survival following heat
stress. A strong interaction between dietary vitamins C and E was
evident in the ACH50. In this study, a level of αTA (31 mg/kg dry
diet) was sufficient to prevent vitamin-E-deficiency signs and
support normal growth.
- Preliminary In vivo investigation on the effect of
isopropyl methyl phosphonic acid on acetylcholine esterase and
xenobiotic metabolizing enzymes of channel catfish, Ictalurus
Punctatus.
Rebecca Lochmann and Harold Phillips
The Pine Bluff Arsenal is charged with the incineration of stored
chemical weapons, including sarin gas. Isopropyl methylphosphonic
acid (IMPA) is a hydrolysis product of the nerve agent Sarin that
could persist in an aqueous environment for years. This study was
designed to understand the effects of IMPA on acetyl
cholinesterase and hepatic xenobiotic-metabolizing enzymes, namely
ethoxy resorufin O-dethylase (EROD), total microsomal cytochrome
P-450's, uridine diphospho-glucoronyl transferase (UDPGT) and
glutathione-S- transferase (GST) of channel catfish, Ictalurus
punctatus. This species was chosen because it is found
naturally in waters near the PBA, and it is cultured in areas that
could be impacted by routine or catastrophic events related to
chemical incineration. Channel catfish were given a single
injection intraperitoneally (IP) of either 0.1, 1.0, 10.0 and
100.0 mg of IMPA per kg body weight or pH-adjusted water as a
carrier control. Fish were collected at 3, 7 and 10 days
post-injection and samples of liver, brain, gills and muscle were
frozen (liquid nitrogen and/or ultracold freezer at –70oC) for
later analysis. All the fish except one at the highest exposure
level survived the 10-day IP period. Localized ulcers on the
ventral side of the abdomen exposing the viscera were observed in
all the fish at the highest exposure level. The results of pending
enzyme analyses will facilitate an understanding of the mechanisms
of toxicity, metabolism and disposition of IMPA in channel catfish
and thereby provide inputs to any future risk assessment programs
related to IMPA.
- Growth, yield and survival of tank-hatched golden shiner
fry fed two practical diets
Rebecca Lochmann and Harold Phillips
A 10-week pond study was conducted to evaluate the growth and
production of tank hatched golden shiner fry fed diets containing
isonitrogenous levels of either fish meal + blood meal, or poultry
meal. Newly hatched fry were stocked on May 7 into 12, 0.1-acre
earthen ponds at a rate of 405,000/acre. During the week prior to
stocking fish, ponds were filled to ˝ of maximum depth
(approximately 1/3rd of total volume) with well water and
fertilized with cottonseed meal at 100 lb/acre and 10-30-0 liquid
fertilizer at a rate of 1 gallon/acre. A second application of
liquid fertilizer at the same rate was made on May 16. Reservoir
water was added slowly to the ponds until they were completely
full on May 23, two weeks after stocking. Two practical diets
simulating commercial minnow meals (36% protein) were made. The
diets contained approximately 8% total of fish meal (FM) plus
blood meal, or poultry meal (PM). Fish were fed twice daily at a
rate of 5 lb/acre/day initially, and the rate was increased to 7
lb/acre/day for the second half of the study. In each pond, pH was
measured every afternoon for the first week, then weekly.
Temperature and dissolved oxygen were measured several times per
week. Zooplankton samples were collected, identified and counted,
and ammonia and Secchi depth were measured weekly. Subsamples of
fish were collected weekly from each pond to track growth using an
image analysis system.
At harvest (July 16-18), all fish were removed from each pond and
bulk-weighed. Individual weights and lengths of fifty fish from
each pond were also determined for calculation of condition. Total
yield did not differ between treatments (538 ± 170 lb/acre and 522
± 119 lb/acre for FM and PM diets, respectively). Feed conversion
averaged 0.9 ± 0.2 for both treatments. Fish fed the FM diet
averaged 3.1 lb/1000 (1.4 ± 0.8 g) at harvest, and were larger (P
= 0.08) than the fish fed the PM diet (1.8 lb/1000 fish, or 0.8 ±
0.2 g). Survival of fish fed the PM diet (79 ± 21%) was higher (P
= 0.09) than that of fish fed the FM diet (54 ± 25%). However, on
the day of stocking, afternoon pH readings were 9.0 to 9.2 in six
ponds and survival at the end of the study was inversely related
to pH on this first day (R2 = 0.71). Of the ponds randomly
assigned to the poultry meal diet, by chance, 5 of the 6 ponds had
first day pH levels below 8.9, while 5 of the 6 ponds assigned to
the fish meal + blood meal diet had pH levels above 9.0. Thus it
is possible that afternoon pH on the day of stocking, or factors
related to the pH, may have contributed to the differential
survival found in the two diet treatments. Condition of fish fed
the PM diet (107 ± 11) was better (P < 0.0001) than that of fish
fed the FM diet (102 ± 9). One week after harvest, groups of 10
fish from each pond that had been retained in the lab and fed
their experimental diets were placed into water with a pH of 10 to
test their stress resistance. Mortalities were counted every 15
minutes for 1 hour. Statistical analysis, taking into account the
difference in average fish weight between the two diets, showed
that fish fed the PM diet had higher mortality (90%) than those
fed the FM diet (68%)(P = 0.05).
- Effect Of ataxanthin on coloration and production
characteristics of goldfish reared in ponds
Rebecca Lochmann and Harold Phillips
Feeder goldfish (Carassius auratus) constitutes nearly $9
million of US aquaculture industry. The market demand is for
appropriately sized goldfish that are red, orange and gold.
Goldfish when hatched are olive-green to bronze and their color
changes at 2-4 months of age. Early onset of color is a desirable
characteristic. The color change is due to accumulation of
carotenoids like astaxanthin in the skin of the goldfish. Goldfish
like other animals cannot synthesize carotenoids de novo and must
obtain it through their food. Astaxanthin in diets are known to
increase color in large goldfish, however information on the
dynamics of pigmentation of juvenile goldfish fed astaxanthin is
limited. This study investigated the effect of astaxanthin in
juvenile goldfish reared in ponds and stability of the color
change when transferred indoors. Three experimental diets
containing 2.8 or 66 or 100 mg/kg of astaxanthin were fed to
duplicate groups of 100 juvenile goldfish (average initial weight
0.8 g) per netpen stocked in 2 ponds for 71 days. Lightness (L*),
redness (a*), yellowness (b*), chroma (C*) and hue (H*) was
measured on 5 fish sampled every week. In addition, the
chlorophyll content of the ponds were measured each week to
quantify natural productivity. There was an increase in L*, a*,
b*, C* and H* as the color of the goldfish turned from olive green
to bright red. However, after 71 days there were no significant
difference (P>0.05) in average individual weight gain, L*, a*, b*,
C* and H* among the different treatments. Seven days after the
initial (outdoor) study, 2 fish from each netpen were stocked in
12 indoor conical tanks. Half of them were fed the same feed as
before while the other half were fed the control diet (2.8-mg
astaxanthin/kg of feed). After 32 days there was a decrease in
color in both the groups, however there were no significant
differences (P>0.05) among treatments within each group. A study
is presently been conducted to evaluate the response of juvenile
goldfish reared in an indoor system to diets containing graded
levels of carotenoids.
- Cortisol response of golden shiner Notemigonus
crysoleucas fed diets differing in lipid content
Rebecca Lochmann and Harold Phillips
The golden shiner (Notemigonus crysoleucas) is the
predominant fish species raised for bait for recreational fishing
in the US. Baitfish are marketed as live products, and they
undergo frequent handling during production and transport to
distribution points. Nutritional enhancement of stress resistance
is probably more important for baitfish than diets that maximize
growth. However, common stress parameters such as the serum
cortisol response have not been studied in this species. The
purpose of this study was to characterize the serum cortisol
response in golden shiners under crowding stress, and to determine
whether dietary lipid composition affects the cortisol response.
In experiment 1, triplicate groups of golden shiners were fed
diets with 4 or 13% menhaden fish oil, or 4 or 13% poultry fat at
3% body weight for 4 weeks before the crowding stress. In
experiment 2, fish were fed diets with10% lipid from cottonseed
oil (CSO), cod liver oil (CLO), soybean oil (SBO), or soybean+cod
liver oil for 6 weeks before the stress test. The diets
represented a wide range of n-3 to n-6 fatty acid ratios (0.0 to
16.7). Serum cortisol was measured initially, two hours after the
stressor was applied, and two hours after the stressor was
removed. Golden shiners were at the upper end of the range of
“intermediate responders” with respect to their cortisol response
relative to other fish species. There were no differences in
cortisol response due to diet.
- Identification of key nutrients in baitfish broodstock
diets to improve egg and larval quality
Rebecca Lochmann and Harold Phillips
Spawning and survival of baitfish fry in captivity is variable.
Tank spawning and hatching methods for golden shiners and fathead
minnows are being developed to increase the supply of high-quality
fry. Maternal nutrition affects the quality and quantity of eggs
and larvae. A series of feeding trials is being conducted to
develop diets to optimize spawning success in golden shiners and
fathead minnnows. In trial 1 (Spring 2002) fathead minnow
broodstock in outdoor pools were fed practical diets containing
10% lipid as soybean oil (SBO), cod liver oil (CLO), a 50/50%
mixture of SBO and CLO, or a 50/50% mixture of SBO and soybean
lecithin. Fish received the diets for approximately 2 months prior
to spawning. A companion study was also stocked in indoor tanks.
However, essentially no spawning occurred in the indoor tanks.
Reasons for this are being investigated. The eggs spawned from
fathead minnows in pools had fatty acid compositions that were
strongly influenced by the prepared diets. Egg hatch rates and
morphometric data on eggs and fry are still being analyzed. Fry
resulting from these eggs were subjected to stress tests in which
they were exposed to high pH (9) for 1 hour. Mortality was highly
variable and no consistent diet effect was seen across tests.
- Apparent digestible energy and nutrient digestibility
coefficients of diet ingredients for pacu Piaractus brachypomus
Rebecca Lochmann and Harold Phillips
The digestible energy and apparent nutrient digestibility
coefficients of common diet ingredients were determined for pacu
Piaractus brachypomus (370.21+17.56g). Fish were fed with pelleted
practical diets to apparent satiation and the feces were collected
by siphoning. The digestibility value for each ingredient was
determined by comparison of the digestibility of a test diet with
a reference diet (26% crude protein and 1% chromic oxide). The
digestible energy values of soybean meal (SBM), fish meal (FM),
corn (CN) and wheat bran (WB) were 2382, 3826, 3353 and 1784
kcal/kg, respectively. The apparent dry matter digestibility
coefficients were 83.72, 90.14, 89.13, and 82.05 % for SBM, FM, CN,
and WB, respectively. The apparent crude protein digestibility
coefficients were 75.88, 90.49, 85.06 and 61.62% for SBM, FM, CN,
and WB, respectively. The apparent lipid digestibility
coefficients were 63.03, 77.00, 83.01 and 82.45% for SBM, FM, CN,
and WB, respectively. The digestibility of protein, lipid, and
energy from SBM were somewhat low compared to values for other
warmwater omnivorous fishes. Otherwise, the nutrient availability
of the ingredients to pacu was similar to that of other fish. This
information will be useful in formulating nutritious, economical
diets for pacu.
- Comparison of regular and hi-fat feeds for golden
shiners
R. Lochmann, N. Stone, H. Phillips and M. Bodary
Golden shiners in fertilized pools were fed one of 3 diets: 1) A
28% protein commercial feed (with about 4% fat), 2) The commercial
feed top-dressed with 9% menhaden fish oil, or 3) The commercial
feed top-dressed with 9% poultry fat. Poultry fat is commonly
included in commercial baitfish diets, but the diets are very low
in n-3 fatty acids which can affect fish performance. The menhaden
fish oil is a rich source of n-3 fatty acids. Both of the
top-dressed diets contained about 13% total fat. Each diet was fed
to fish in six 4137-L pools. Each pool was stocked with shiners
weighing 0.7 g initially at a rate of 750,000 fish/ha (500
fish/pool). Fish were fed 6% b.w. daily in two feedings from
7/30/02 to 10/30/02 (3 mos.). At the end of the study average
individual weight gain was highest in fish fed the regular
commercial feed. However, survival and net yield were
significantly higher in fish fed either high-fat diet (with no
differences due to fat source). Groups of fish from each pool were
kept on the same diets for 1 week after harvest. Then subsets of
these fish were subjected to either sudden or gradual increases in
water temperature (max. 34-36oC), or a sudden drop in temperature
(20 to 10oC) followed by maintenance at 6-7oC for 48 h. There were
no differences due to diet in the cold stress test. However, fish
fed the hi-fat menhaden fish oil diet had higher survival in both
heat stress tests relative to fish fed the regular or hi-fat
poultry fat diets.
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