Total Ammonia Nitrogen Excretion Rates Research Articles

Dietary glycerol inclusion decreases growth performance and nitrogen retention efficiency in rainbow trout (Oncorhynchus mykiss)

Glycerol is an inexpensive source of dietary energy, although its inclusion in compound feeds has been barely investigated in fish. The effects of dietary refined glycerol inclusion on growth performance, nitrogen and energy balance, as well as its digestibility and intestinal digestive enzyme activities was studied in rainbow trout. Fish (initial BW 20.2 ± 0.1 g, mean ± SE) were divided into nine tanks (1.66 kg m−3), each one assigned to the experimental diets, in triplicates. Fish were fed twice a day to apparent satiation for 60 days three diets including 0, 25, or 50 g kg−1 of refined glycerol (G0, G25, and G50, respectively) with similar digestible protein to energy ratios (22 mg kJ−1). A digestibility trial was conducted in parallel to the growth trial by using a Choubert System to collect feces, in triplicates. Refined glycerol was well digested (ADCglycerol > 99.7%) when included up to 50 g kg−1. Specific growth rate (SGR) decreased as glycerol inclusion levels increased in the diet (P = 0.029). Feed intake was enhanced with increasing dietary inclusion levels of glycerol (P = 0.013). The feed efficiency decreased linearly as the glycerol inclusion levels increased in the diet, reflected in a higher FCR ratio, particularly in the G50 group compared to the G0 or G25 groups (1.04 ± 0.02, 0.90 ± 0.02 and 0.91 ± 0.02, respectively). Total ammonia nitrogen excretion rate (TANER) was measured in trout at the end of the growth trial, displaying increased values with higher dietary glycerol inclusion levels (P < 0.001). As a result, trout fed G25 or G50 diets displayed an increased energy intake, which was not reflected in a reduction of the nitrogen excretion rate. Contrary to expected, glycerol had a negative effect on nitrogen efficiency, indicating that dietary inclusion of this compound does not spare the use of proteins as a metabolic fuel. In addition, amylase, but not proteases and lipase, was altered in the intestine of trout by refined glycerol inclusion, as this digestive enzyme activity increased 6 h post-feeding in trout fed G25 and G50 diets. In conclusion, dietary refined glycerol inclusion on rainbow trout was not reflected in beneficial effects on fish performance or in the quantity of nitrogen waste products excreted to the environment by this carnivorous species.

Effect of some common West African farm-made feeds on the oxygen consumption and ammonia excretion rates of Nile tilapia, Oreochromis niloticus

The effects of two common West African farm-made feeds on postprandial metabolism were assessed in adult Nile tilapia (Oreochromis niloticus) by quantifying the oxygen consumption rates (MO2) and total ammonia-nitrogen (TAN) excretion over a 24-h period. Measurements followed the ingestion of a single meal of a fishmeal-based control diet and two diets containing 30% copra (CM) or palm kernel meal (PKM) inclusions by groups of 15 adult O. niloticus per tank. The mean net MO2 (postprandial oxygen consumption corrected for routine metabolic rate) during digestion for the different tilapia groups varied narrowly between 112.2 ± 9.9 and 129.9 ± 20.4 mg O2 kg−1 h−1 with the fish fed the CM diet recording a significantly lower (p = 0.04) net MO2 response relative to the other two diets. Net TAN excretion rates of the different dietary groups varied between 3.4 ± 1.4 and 4.4 ± 1.6 mg TAN kg−1 h−1. Under the standardized experimental conditions, copra and PKMs appeared to be promising candidates as partial replacements to fishmeal in tilapia diets as far as rates of oxygen consumption and ammonia-nitrogen excretion are concerned.

Excreción de nitrógeno amoniacal total a diferentes densidades de siembra de Cyprinus carpio en condiciones de laboratorio

En sistemas acuícolas la excreción de nitrógeno amoniacal total (NAT) está determinada por varios parámetros biológicos y fisicoquímicos como la densidad de siembra. Si no hay un adecuado control de NAT el consumo de alimento y el crecimiento disminuye eventualmente conduciendo a la muerte. Por lo tanto, definir la relación entre la densidad de siembra y la tasa de excreción de NAT, es importante para establecer las condiciones adecuadas para el crecimiento. En el presente trabajo se utilizó como modelo experimental la carpa común (Cyprinus carpio). Se evaluaron dos tratamientos: T1, 30 individuos y T2, 60 individuos por unidad experimental (acuarios de 40 l) con tres repeticiones. Los cuales fueron medidos (peso, longitud total y estándar) al inicio y cada 14 días. Semanalmente se realizó seguimiento de pH, temperatura, dureza de carbonatos y general. Para el registro del NAT y oxígeno disuelto, se tomaron muestras cada cuatro días. La tasa de excreción de NAT fue calculada por periodos de 14 días. Los resultados obtenidos para la tasa de excreción de NAT fueron: el día 14 para el T1 = 0.69±0.009 µg g-1 hora-1, con una biomasa de 18.33±0.13 g; para el T2 = 0.40±0.02 µg g-1 hora-1 y biomasa de 34.66±0.33 g; el 28 para el T1 = 0.53±0.02 µg g-1 hora-1, con una biomasa de 24.8±0.3g; para el T2 = 0.28±0.03 µg g-1 hora-1 y biomasa de 48.99±2.58 g; y el 42 para el T1 = 0.47±0.02 µg g-1 hora-1, con una biomasa del 32.3±1.7 g; para el T2 = 0.26±0.02 µg g-1 hora-1 y biomasa de 69.81±7.04 g. Después de estos resultados se puede concluir que a mayor densidad de siembra la tasa de excreción de amonio total por gramo disminuye.

温度和体重对克氏双锯鱼仔鱼代谢率的影响

The clownfishes,or sea anemonefishes,of the genus Amphiprion and Premnas with approximately 30 species,belong to the Subfamily Amphiprioninae,the Family Pomacentridae.Many clownfishes are popular in the tropical marine ornamental fish trade.In recent years,the clownfishes remain the Ranking One in the trade based on the estimated annual amount of individuals sold.Hatchery-based larviculture and grow-out of clownfishes have been developed in several countries.In China,at least six species can be hatchery-produced and grown up to marketable sizes of 3—5 cm total length,including Yellowtail clownfish A.clarkii,Tomato clownfish A.frenatus,Orange clownfish A.percula,Pink Skunk Clownfish A.perideraion,Saddleback clownfish A.polymnus and Maroon Clownfish P.biaculeatus. Metabolic rate indicates the efficiency of food and energy intake,conversion and allocation,and is influenced by fish body condition and environmental factors.Respiration and excretion are the two main components of metabolism.Respiration rate can be calculated through the measurement of total oxygen consumption,and excretion rate can be calculated through the measurement of total ammonia nitrogen excretion.Based on the oxygen/nitrogen ratio,the energy sources that fish utilized mainly for somatic growth can be determined. This study was conducted to investigate the effects of water temperature and body weight on respiration and excretion of Yellowtail clownfish Amphiprion clarkii during its larval development from newly-hatched to the complement of metamorphosis.Larvae were reared at three water temperatures of 23,26 and 29℃ in captivity.Individual respiration rate(RR,μg O2 ind-1 h-1) and individual total ammonia nitrogen excretion rate(ER,μg N ind-1 h-1) of A.clarkii were measured,respectively.The results showed that RR and ER increased with body weight(W,mg) as a power function of R = aWb at all three water temperatures.The b-values were 0.8873,0.9033 and 0.9323 for RR,and 0.7625,0.8012 and 0.8278 for ER,at 23,26 and 29℃,respectively.RR and ER at 29℃ were significantly higher than those at 23 and 26℃(P0.01).Multiple regression analyses showed the variability in the integrated effects of temperature(T,℃) and W on RR and ER: RR= 0.042W0.889×e0.122T and ER = 0.002W0.797×e0.115T.At the same water temperature,both respiration rate per body weight(RR′,μg O2 mg-1 h-1) and total ammonia nitrogen excretion rate per body weight(ER′,μg N mg-1 h-1) in larvae of A.clarkii decreased with the increase of W.With the increase of water temperature,RR′ and ER′ increased.RR′ and ER′ at 29℃ were significantly higher than those at 23 and 26℃(P0.05).The oxygen/nitrogen ratios(O/N) in larvae of A.clarkii were around 52-57 at all three water temperatures,and showed no difference(P0.05),indicating that the main energy sources for larval development are protein,fat and carbohydrate.High temperature effects(Q10) for both respiration and excretion were found over the water temperature range of 23—26℃,with 3.70 and 4.01,respectively.Low Q10 for respiration was found at 26—29℃ with a value of 2.40,and low Q10 for excretion was found at 23—29℃ with a value of 2.5.This study reveals that the optimal water temperature for larval development of A.clarkii lies between 26 and 29℃.

Effects of Temperature and Stocking Density on the Ammonia Excretion Rate of Red Seabream, Pagrus major

An experiment was conducted to investigate the effects of temperature and stocking density on daily patterns and rates of total ammonia nitrogen (TAN) excretion in juvenile red seabream Pagrus major (mean body weight: 29.0 g) under fasting and feeding conditions. Fish were acclimated over 7 days under four different temperatures (10, 15, 20, and <TEX>$25^{\circ}C$</TEX>) and at two different densities (5.5 and <TEX>$11.0\;kg\;m^{-3}$</TEX>). Each treatment had three replicates and a total of 216 fish were used. After 72 hours starvation, endogenous TAN excretion was measured for each temperature and density. To investigate exogenous TAN excretion, fish were handfed a commercial diet containing 51.6% crude protein twice a day for 7 days, at 08:00 and 16:00. Water was sampled from both inlets and outlets of chambers every 2 hours over a 24 hour period. Both endogenous and exogenous TAN excretion increased with increases in temperature and density (P<0.05). Mean daily endogenous TAN excretion rates at 10, 15, 20, and <TEX>$25^{\circ}C$</TEX> were 88.8, 101.1, 125.0, and <TEX>$143.3\;mg\;TAN\;kg^{-1}\;d^{-1}$</TEX> at low density, and 105.2, 119.2, 141.5, and <TEX>$168.8\;mg\;TAN\;kg^{-1}\;d^{-1}$</TEX> at high density, respectively. Mean daily exogenous TAN excretion rates at 10, 15, 20, and <TEX>$25^{\circ}C$</TEX> were 343.5, 403.7, 535.7, and <TEX>$601.7\;mg\;TAN\;kg^{-1}\;d^{-1}$</TEX> at low density, and 391.9, 479.7, 611.9, and <TEX>$683.4\;mg\;TAN\;kg^{-1}\;d^{-1}$</TEX> at high density, respectively. The exogenous TAN excretion rate peaked 10~12 hours after the first feeding under all temperatures and densities. The TAN loss for ingested nitrogen increased with increases in temperature and density (P<0.05), ranging from 27.9 to 50.1% at low density and 31.7 to 56.9% at high density. This study provides empirical data for estimating ammonia excretion and managing the culture of red seabream under the given temperatures and densities.

볼락 Sebastes inermis 치어의 암모니아 배설에 미치는 수온의 영향

A study was carried out to investigate the effect of water temperature on daily pattern and rate of total ammonia nitrogen (TAN) excretion in juvenile dark-banded rockfish Sebastes inermis (mean body weight: <TEX>$14.8{\pm}0.3g$</TEX>) under fasting and feeding conditions. Fish were acclimated over 10 days under three different water temperatures (15, 20 and <TEX>$25^{\circ}C$</TEX>). After 72 hours of starvation, fasting TAN excretion was measured at each temperature. To investigate post-prandial TAN excretion, fish were hand-fed with a commercial diet containing 47.7% crude protein for 7 days, two times daily at 09:00 and 17:00 hr. Water was sampled from both the inlet and outlet of each chamber every 2 hrs over a 24 hr period. Both fasting and post-prandial TAN excretion increased with increase in water temperature (P<0.05). Mean fasting TAN excretion rates at 15, 20 and <TEX>$25^{\circ}C$</TEX> were 8.1, 9.0 and 9.2 mg TAN kg <TEX>$fish^{-1}h^{-1}$</TEX>, respectively. The value of <TEX>$15^{\circ}C$</TEX> was lower than those of 20 and <TEX>$25^{\circ}C$</TEX> (P<0.05), but there was no significant difference between <TEX>$20^{\circ}C$</TEX> and <TEX>$25^{\circ}C$</TEX> (P>0.05). Mean post-prandial TAN excretion rates at 15, 20 and <TEX>$25^{\circ}C$</TEX> were 20.1, 22.9 and 23.4 mg TAN kg <TEX>$fish^{-1}h^{-1}$</TEX>, respectively. A peak post-prandial TAN excretion rate occurred after 12 hrs from the first feeding at <TEX>$15^{\circ}C$</TEX> (mean 28.7 mg TAN kg <TEX>$fish^{-1}h^{-1}$</TEX>), <TEX>$20^{\circ}C$</TEX> (33.7 mg TAN kg <TEX>$fish^{-1}h{-1}$</TEX>) and <TEX>$25^{\circ}C$</TEX> (36.8 mg TAN kg <TEX>$fish^{-1}h{-1}$</TEX>), respectively. The TAN loss for ingested nitrogen at <TEX>$15^{\circ}C$</TEX> (36.2%) was lower than that of <TEX>$20^{\circ}C$</TEX> (40.8%) and <TEX>$25^{\circ}C$</TEX> (41.7%). Based on overall results, water temperature exerts a profound influence on the nitrogen metabolism of juvenile dark-banded rockfish.

Ammonia excretion dynamics in the east coast rock lobster Panulirus homarus rubellus

An understanding of the ammonia excretion dynamics of the east coast rock lobster Panulirus homarus rubellus is necessary to inform suitable holding, growout and transport protocols. The effect of body weight, emersion, daily rhythm, feeding and ambient ammonia on the total ammonia nitrogen (TAN) excretion rate was investigated. Body weight (range of 16.8 g–322 g; n = 16) was positively correlated to daytime TAN excretion rate (mg h − 1 ) according to the equation: log 10 (log 10TAN + 2) = 1.176 log 10 (log 10 W) − 0.316 ( r 2 = 0.68, F = 30.24, P < 0.0001). Re-immersion after 1 h emersion in a moist environment was characterized by a significant increase in TAN excretion rate for the first hour compared to pre-immersion levels. The amount of TAN excreted during this period was as expected if basal TAN excretion rates were maintained during emersion. TAN excretion rates returned to pre-emersion levels by the end of the second hour. There was no evidence of a daily rhythm in TAN excretion rate for P. h. rubellus. TAN excretion rates were elevated following feeding. An initial peak in TAN excretion rate after 7 h (7.58 pre-feeding rate) was followed by a smaller peak after 13 h (6.69 times pre-feeding rate). Following ingestion of feed, the TAN excretion rate was initially significantly different from pre-feeding levels after 23 h and consistently returned to pre-feeding levels after 42 h. The TAN excretion rates of lobster exposed for 2 h to an ambient TAN concentration of 1.02±0.10 mg l − 1 ( t = 0.54, P = 0.59, n = 9) and 2.3 ± 0.2 mg l − 1 (Mann–Whitney U Test, Z = 1.46, P = 0.16) were not significantly different from TAN excretion rates recorded at low ambient water TAN (0.02 ± 0.02 TAN mg l − 1 ) prior to exposure. Exposure to an ambient TAN concentration of 4.45 ± 0.78 mg l − 1 (Mann–Whitney U Test, Z = 3.58, P = 0.0003) had a significant effect on the TAN excretion rate, with pronounced ammonia uptake occurring for all animals at this concentration.

Nitrogen Excretion in Fed and Fasted Lake Sturgeon

AbstractLake sturgeon Acipenser fulvescens are imperiled throughout their native range, and hatchery‐reared fish are often stocked to facilitate population restoration. However, the rearing of hatchery fish requires knowledge of nitrogenous excretion rates for efficient culture system design and maintenance. Total ammonia nitrogen (TAN) and urea nitrogen (UN) excretion rates were quantified in age‐0 lake sturgeon that were either fasted or fed brine shrimp Artemia spp. In the first experiment, fish of three different size‐classes (small [10–20 g], medium [50–65 g], and large [100–120 g]) were fasted for 5 d, and their nitrogenous excretions were measured at the end of this period. In the second experiment, lake sturgeon from different size‐classes were fed low (0.5% of body weight [BW] on a dry‐matter basis, 4.2% BW on a wet‐weight basis), and high (1% BW on a dry‐matter basis, 8.3% BW on a wet‐weight basis) rations of Artemia. No UN was detected in fasted lake sturgeon. Endogenous TAN excretion rates varied inversely with fish size. The mean endogenous TAN excretion rate in fasted small lake sturgeon (37.42 mg·kg−1·d−1) was significantly higher than the TAN excretion rates in medium (13.72 mg·kg−1·d−1) and large (6.02 mg·kg−1·d−1) fish. The mean TAN excretion rate in fed small fish (117.34 mg·kg−1·d−1) was significantly higher than the rates in medium (33.69 mg·kg−1·d−1) and large (26.29 mg·kg−1·d−1) fish. Ration size did not significantly affect TAN excretion rates, and mean UN excretion rates in fed fish were not significantly affected by either fish size or ration size. These results suggest that lake sturgeon, like most teleost fishes, predominantly excrete ammonia. The estimates for nitrogen excretion from this study will aid in determining rearing densities for juvenile lake sturgeon in culture systems.

Elevated oxygen uptake and high rates of nitrogen excretion in early life stages of the cobia Rachycentron canadum (L.), a fast‐growing subtropical fish

Physiological energetics of cobia Rachycentron canadum were quantified for 18 to 82 days post‐hatch (dph) hatchery‐reared juveniles to better understand energy transformation and its implications in growth and survival. Mean oxygen consumption rates (; mg O2 h−1) of fish fed ad libitum and fish that were starved significantly increased with increasing wet mass (M; g), = 1·4291M0·8119 and = 1·1784M0·7833, respectively, with a significant reduction in mean metabolic rates of starved fish (19 to 27% specific dynamic action; SDA). Total ammonia nitrogen excretion rates (AMM, μmol h−1) also scaled with M and significantly decreased after starvation. Mean mass‐specific AMM and urea excretion rates are the highest reported in the literature, with urea accounting for approximately half the total nitrogen excretion measured in both fed and starved fish. Relatively high energetic rates may allow cobia to develop rapidly into pre‐juveniles and be less susceptible to predation and starvation at a comparatively early age.

Ammonia and urea excretion rates of California halibut ( Paralichthys californicus, Ayres) under farm-like conditions

In the design and optimization of aquaculture water recirculation and treatment technologies, it is important to know the nitrogen excretion rates of the fish being cultured. Rates of total ammonia nitrogen (TAN) and urea-N excretion were measured for California halibut of 4.2, 7.2, 10.4, 20.1, 112 and 199 g mean mass. The fish were fed with a feed of a size-appropriate pellet containing 43–45% protein continuously over 12 h during the light hours (photoperiod of 16 h daylight and 8 h dark). Feeding was started 2 h into the light period after the tanks had been cleaned and routine water analyses had been made. Daily average TAN excretion rates ranged from 4.3 to 8.5 mg TAN/g feed, and urea-N excretion rates ranged from 0.8 to 1.8 mg urea-N/g feed. Corresponding values relative to fish mass were between 91 and 113 mg TAN/kg fish d and between 13 and 20 mg urea-N/kg fish d. Peaks of TAN excretion occurred 4–6 h after feeding had started and 6–10 h after conclusion for the 4–20 g fish. Corresponding values for the 112 and 199 g fish were 10–12 h after feeding had started and 8–10 h after feeding ended. Some minor fluctuations in the urea excretion rates were noted, but there were no consistent peaks. TAN excretion accounted for 81.6 to 88.1% of the total daily urea-N plus TAN excretion by California halibut with the balance consisting of urea-N excretion. Although urea-N makes up a relatively small portion of the total daily nitrogen excretion by California halibut, there were times during the day during when the hourly urea-N excretion rate was similar to or larger than the corresponding TAN excretion rate. All excretion measurements were made under farm-like conditions with fish reared in a marine recirculating system.

Ammonia and urea excretion of the nemertean Procephalothrix simulus Iwata: effects of salinity, temperature, body weight and amputation

The total ammonia nitrogen (TAN) and urea nitrogen excretion of the nemertean Procephalothrix simulus Iwata was determined under different conditions. Both of its ammonia and urea excretion rates increased with the elevation of water temperature, and the relationship between the TAN excretion rate and water temperature could be described by TAN (μg N g − 1 h − 1 ) = 20.510 e 0.071 t ( R 2 = 0.943, F = 83.47, P < 0.001). When the salinity was elevated from 10‰ to 45‰, the ammonia excretion rate firstly increased and then decreased, with the peak value being obtained at 20‰. The urea excretion, however, showed a positive relationship with salinity. The whole animal TAN excretion increased with the increase of body weight [TAN (μg N h − 1 ) = 15.853 W 0.65 ( R 2 = 0.871, F = 458.73, P < 0.001)], while the weight specific rate of TAN excretion was negatively related with body weight [TAN (μg N g − 1 h − 1 ) = 15.858 W − 0.35 ( R 2 = 0.661, F = 132.55, P < 0.001)]. When worms were bisected, the anterior body fragments had lower and the posterior body fragments had higher TAN excretion rate, suggesting that most of the ammonia was not eliminated by the excretory organs in this nemertean species. Results also showed that the anterior body fragments were faster than the posterior body fragments in regaining the normal level of ammonia excretion.

한국산 선발 계통, 일본산 양식 계통 그리고 이들 두 계통간 잡종 계통 참돔 치어의 총 암모니아성 질소 배설률 및 분 배출률을 통한 사료내 단백질 이용 효율 비교

An experiment was conducted to investigate the differences of total ammonia nitrogen (TAN) excretion rates and feces production rates among the offsprings from cultured Japanese strain (JJ, mean BW; ), intraspecific hybrid strain between cultured Japanese and selected Korean strain (JK, mean BW: ) and selected Korean strain(KK, mean BW: ) of red sea bream in order to compare their dietary protein utilization efficiency. Fish were hand-fed with a commercial diet containing 46.7% crude protein for 2 weeks, three times daily 09:00, 13:00 and 17:00. After daily feeding, the TAN excretion rates reached peaks of 49.03, 58.75 and 36.26mg/kg fish/hr for the JJ, JK and KK strain, respectively, during the daytime. The value of the KK strain was significantly lower than that of the JJ and JX shuin (P0.05). When fish were fed at satiation after 4 days of starvation, TAN excretion rates reached the maximum values 4 hours after the feeding fur the KK (31.23 mg/kg fish/hr) and 6 hours after the feeding fur the JJ (44.19 mg/tg fish/hr) and JK strain (41.70 mg/kg fish/hr). After 3 days of starvation, the daily endogenous TAU excretion rates (ETE) for the JJ, JK. and KK strain were 286.91, 215.66 and 179.29mg/kg fish/day, respectively. The value of the KK strain was lower than that of the JJ and JK strain (P

Nitrogen and phosphorus digestibility and excretion of different-sized groups of milkfish (Chanos chanosForsskal) fed formulated and natural food-based diets

This study determined the digestibility of nitrogen and phosphorus, and the excretion rate of different-sized groups of milkfish fed a commercial diet, a SEAFDEC formulated diet or lab-lab (natural food-based diet). Fish (31.2–263.0 g) were stocked in 12 units of 300-L fibreglass tanks filled with aerated seawater. The postprandial total ammonia-nitrogen (TAN) and phosphate (PO4-P) excretion of fish were estimated from changes in TAN and PO4-P concentrations in water for 24 h. Digestibility was determined from the nitrogen, phosphorus and Cr2O3 content of the diets, and pooled faeces after the fish had been fed diets marked with chromic oxide. TAN excretion rate (mg TAN kg−1 fish day−1) was significantly lowest (P < 0.05) in medium to very big fish fed the lab-lab diet (60.8–124.4) and highest in small and medium fish fed the SEAFDEC diet (333.3–331.6) and small fish fed the commercial diet (280.1). Regardless of size, fish fed lab-lab excreted (mg PO4-P kg−1 fish day−1) significantly lower PO4-P (36.2) but did not differ with fish fed the commercial diet (64.8). Excretion rates decreased exponentially as fish weight increased but positively increased with feed ration. Excretion pattern of milkfish revealed two peaks: the first peak occurred 6 h after feeding and the second peak at 18 h for TAN and 21 h for PO4-P, coinciding with the start of the daylight hours. TAN and PO4-P excretion accounted for 20.5–34.6% of total N consumed and 18.7–42.6% of P consumed respectively. Approximately 27.9–42.5% of N consumed and 47.2–58.5% of P consumed were lost as faeces. Total nutrient losses were lower using the lab-lab diet (0.31 g N and 0.14 g P kg−1 fish) compared with the formulated diets (0.47–0.48 g N and 0.17–0.19 g P kg−1 fish); the losses decreased per kg of fish as fish size increased. Results suggest that the diet and size of fish influence wastage of N and P to the environment with greater losses in small fish and when artificial diets are used. Such measurements will provide valuable information for the preparation of N and P budgets for milkfish in grow-out systems.

Ammonia Nitrogen Excretion Rate - An Index For Evaluating Protein Quality Of Three Feed Fishes For The Black Sea Turbot

Total ammonia nitrogen excretion rates were measured in young Black Sea turbot (74.79 g avg wt) reared in brackish water (17 ppt salinity) at 11±0.3°C. Duplicate groups of turbot were fed a fixed quantity of teleosts, either anchovy (Engraulis encrasicolus), goby (Gobius sp.) or whiting (Merlangius merlangus). Feeds were offered to the turbot as wet feed. Cumulative ammonia-N excretion over a 6-hour period was significantly lower (p&lt;0.05) in fish fed goby (3.64±0.27 mg- N/100 g fish) and whiting (3.83±0.13 mg-N/100 g fish) than that in fish fed anchovy (4.48±0.06 mg-N/100 g fish). The ammonia-N excretion rate in all groups peaked two hours after feeding, but the peak value in the group fed anchovy was significantly higher (p&lt;0.05) than in the other two groups. No differences were observed among diets in samples taken 3, 4, 5 and 6 hours after feeding. Significantly lower excretion levels in the goby and whiting groups could be relat- ed to the protein quality of these species which may be higher than that of the anchovy for tur- bot nutrition.

Feeding has the largest effect on the ammonia excretion rate of the southern rock lobster, Jasusedwardsii, and the western rock lobster, Panuliruscygnus

The total ammonia nitrogen (TAN) excretion of spiny lobsters Jasus edwardsii and Panulirus cygnus, was determined in relation to temperature, body weight, emersion, daily rhythm and feeding. Temperature and body weight had large influences on the rate of TAN excretion. Exponential relationships were found between temperature ( T) and TAN excretion of both species. These were described by the following equations: J. edwardsii Log 10 TAN=0.041 T−3.57 ( r 2=0.979, F=143.2, P=0.001), P. cygnus Log 10 TAN=0.057 T−3.90 ( r 2=0.987, F=302.2, P<0.001). TAN excretions of both species were positively correlated to body weight ( W), and the relationships were described by the following equations: J. edwardsii Log 10 TAN=0.473 log 10 W−1.704 ( r 2=0.42, F=14.05, P=0.001), P. cygnus Log 10 TAN=0.499 log 10 W−1.346 ( r 2=0.69, F=44.18, P<0.001). TAN excretion increased significantly when lobsters were re-immersed after a 30 min period of emersion. However, it returned to pre-emersion levels by the second hour of re-immersion. Daily rhythm resulted in a significantly higher nocturnal TAN excretion rate for J. edwardsii; no daily rhythm was observed for P. cygnus. Feeding had the largest influence on TAN excretion, with maximum increases of 6.28 ( J. edwardsii) and 5.60 ( P. cygnus) times the pre-feeding level. TAN excretion rates remained significantly higher than the pre-feeding levels for an extended period (26 h, J. edwardsii; 30 h, P. cygnus). Implications for the use of purging tanks in lobster holding facilities and for the design of biofiltration systems are discussed.

Effects of dietary carnitine and protein energy:nonprotein energy ratios on growth, ammonia excretion and respiratory quotient in African catfish,Clarias gariepinus(Burchell) juveniles

Two separate feeding experiments were carried out to determine the effects of dietary carnitine supplements on growth rates, total ammonia nitrogen (TAN) excretion and respiratory quotient rates (RQ) in the African catfish, Clarias gariepinus (Burchell), juveniles fed various diets differing in protein energy:nonprotein energy ratio (PE:NPE). In Experiment 1, 540 fish (20.9 ± 1.0 g) were evenly distributed into six dietary groups and fed in duplicate aquaria (N = 12 aquaria) to apparent satiation over a 41-day period, until all fish attained an individual final weight of 156.9 ± 10.8 g. Diets were formulated to contain two levels of carnitine (80 and 660 mg kg−1) and three levels of PE:NPE (0.7, 0.9 and 1.4). Sampling was divided into two size ranges, according to the predicted individual end-weight of 60 g (days 0–16) and 160 g (days 16–41). In Experiment 2, 240 fish (16.5 ± 0.2 g) were distributed in four 140-L aquaria connected to a respirometer and preconditionally fed twice a day at a restricted feeding level of 24 g kg−0.8 day−1 for a 25-day period (final weight of 77.5 ± 1.5 g). Four isonitrogenous diets (368 g kg−1 crude protein) were formulated to contain two levels of fat (85 and 175 g kg%−1) and two levels of carnitine (40 and 600 mg kg−1), in a 2 × 2 factorial design. From days 20–25, three respirometric trials were carried out, during which total ammonia nitrogen (TAN) and RQ were determined over 24 h. In both experiments, carnitine supplemented fish accumulated 2.5−4 times more carnitine in their tissues than fish fed a basal level (P < 0.05). In Experiment 1, the smallest fish (<60 g) fed 660 mg carnitine showed significantly higher growth rates and lower feed conversion rates than 80 mg carnitine supplemented fish only when the dietary PE:NPE ratio was low (0.7). Additionally, dietary carnitine significantly increased protein:fat ratios in the whole body, suggesting a protein-sparing action. In Experiment 2, high carnitine supplements decreased both TAN excretion and RQ rates in fish <80 g.

Waste excretion characteristics of Manila clams ( Tapes philippinarum) under different temperature conditions

Water recirculating systems have been used in the shellfish industry for depuration and wet-storage. Knowledge of shellfish excretion characteristics is critical to recirculating system design. In this study, the excretion rate of total ammonia nitrogen (TAN), total Kjeldahl nitrogen (TKN), and 5-day biochemical oxygen demand (BOD 5) from Manila clams ( Tapes philippinarum) were investigated under both laboratory and commercial conditions. The laboratory tests were conducted under temperatures ranging from 3 to 30°C. The experimental results showed that temperature was a key factor in determining the excretion rate of all the above parameters. The relationship between TAN excretion rate ( R TAN) and temperature ( T) can be represented by an exponential function ( R TAN=0.57×1.25 T ). For the temperature range between 3 and 20°C, the daily mean excretion rates of TAN, TKN and BOD 5 ranged between 1.5–46.1, 4.8–131.0 and 57.4–219.4 mg per kilogram of the clams (wet weight with shell on), respectively. There were linear correlations between TAN, TKN and BOD 5 production rates. The data presented in this paper can be used to estimate waste generation from a given shellfish processing operation and to size the waste treatment components for a recirculating depuration (or wet-storage) system.

Northern quahog, Mercenariamercenaria, seed clam waste characterization study: precursor to a recirculating culture system design

The high demand and price of the northern quahog, Mercenaria mercenaria, enable this species to be an excellent commercial aquaculture candidate for coastal Georgia. The most economical method to grow clams is in the natural environment at controlled densities. Commercial nurseries grow small seed from the hatchery (1–2 mm) to a size suitable for planting in the field (8–10 mm). The pivotal role of the nursery phase to the success of bivalve mariculture has prompted research into improving nursery culture systems. Utilizing recirculation technology can contribute to the development and success of land-based nursery systems that offer higher survival and faster growth than field-based systems. This paper presents baseline excretion data that can be useful in the design of a recirculating system for culturing bivalve Mercenaria seed clams in a land-based system. The total ammonia nitrogen excretion rate based on a 24-h isolation period ranged from 20.0 to 89.4 μg NH 4N g clam −1 day −1 for Mercenaria seed clams with a shell length ranging from 3.0 to 12.6 mm. The low ammonia production rate combined with the high ammonia tolerance limits of bivalves minimizes the need for a biofilter unit. The BOD 5 loading rate was highly variable and ranged from 0.05 to 0.32 mg l −1-O 2 g clam −1 day −1. For the seed clams that were less than 8 mm in shell length, the effluent total suspended solids concentration was three times greater than the larger size clams (10–12 mm shell length). Results indicated the importance of a solids removal mechanism to decrease the BOD 5 loading rate and reduce potential psuedofaeces production.

Effects of body weight, water temperature and ration size on ammonia excretion by the areolated grouper ( Epinephelus areolatus) and mangrove snapper ( Lutjanus argentimaculatus)

The effects of body weight, water temperature and ration size on ammonia excretion rates of the areolated grouper Epinephelus areolatus and the mangrove snapper Lutjanus argentimaculatus were investigated. Under given experimental conditions, L. argentimaculatus had a higher weight-specific ammonia excretion rate than E. areolatus. Weight-specific ammonia excretion rates of fasted individuals of both species showed an inverse relationship with body weight ( W, g wet wt.), but a positive relationship with water temperature ( t, °C). The relationships for total ammonia nitrogen (TAN) were: E. areolatus: TAN (mg N kg −1 d −1)=21.4·exp 0.11 t · W −0.43 ( r 2=0.919, n=60); L. argentimaculatus: TAN (mg N kg −1 d −1)=121.5·exp 0.12 t · W −0.55 ( r 2=0.931, n=60). Following feeding, the weight-specific ammonia excretion rate of E. areolatus increased, peaked at 2 to 12 h (depending on temperature), and returned to pre-feeding levels within 24 h. A similar pattern was observed for L. argentimaculatus, with a peak of TAN excretion being found 6 to 12 h after feeding. Stepwise multiple regression analysis indicated that weight-specific TAN excretion rates of both species increased with increasing temperature and ration ( R, percent body wt. d −1): E. areolatus: TAN (mg N kg −1 d −1)=22.8· t−28.8· R−378.2 ( r 2=0.832, n=24); L. argentimaculatus: TAN (mg N kg −1 d −1)=22.9· t−25.4· R−216.4 ( r 2=0.611, n=24). The effect of body weight on weight-specific postprandial TAN excretion was not significant in either species ( p>0.05). This study provides empirical data for estimating ammonia excretion of these two species under varying conditions. This has application for culture management.

Kemp's Ridley Sea Turtle Waste Characterization Study: Precursor to a Recirculating Holding System Design

AbstractThe decreasing population of the endangered Kemp's ridley sea turtle (Lepidochelys kempi) has necessitated research into more cost effective captive nurseries. Captive nurseries are an attempt to increase the survival of the Kemp's ridley past the first year of life. Presently, Kemp's ridleys are reared in captivity at the Headstart rearing facility in Galveston, Texas. This facility consists of a labor intensive, flow‐through system. Alternatively, recirculating systems permit development of inshore facilities with decreased labor and operating costs. This paper presents baseline excretion data necessary for designing filtration units required for water quality maintenance in recirculating holding systems. The total ammonia nitrogen excretion rate based on a 24 hour isolation period (fed) was fairly constant at 0.19 mg N/g‐turtle‐day, while the BOD5 loading rate was highly variable, averaging nearly 0.50 mg O2/g‐turt1e‐day. In addition, comparisons of filtered versus nonfiltered samples suggest that a suspended solids removal mechanism prior to the filtration unit would dramatically decrease BOD5 and, thus, improve filter efficiency and increase its capacity.