Stocking Density Research Papers - Academia.edu (original) (raw)

The HOBAS aeration system was tested to compare changes in environmental and bacteriological parameters in ponds growing Penaeus monodon during a single production cycle. The stocking density in the aerated pond was doubled to 12... more

The HOBAS aeration system was tested to compare changes in environmental and bacteriological parameters in ponds growing Penaeus monodon during a single production cycle. The stocking density in the aerated pond was doubled to 12 post-larvae (PL) m − 2 in contrast to the non-aerated pond with 6 (PL) m − 2. Microbial abundance in the ponds ranged between 105 − 6 cells ml − 1. Among the physiological groups of bacteria enumerated, the heterotrophs dominated with an abundance of 104 CFU ml − 1. Of the nitrogen and sulfur cycle bacteria, the nitrifiers flourished in the aerated pond and could maintain ammonia-N concentration within permissible levels. Bacterial activity also maintained sulfide concentrations at − 1. Non-aerated conditions promoted denitrification maintaining nitrate concentration between 0.32 and 0.98 μM NO3 − -N l − 1. However, a marked increase in ammonium content was observed in the non-aerated pond at the end of the culture period. Thus in high-density ponds, the aerators served to stimulate bacterial growth and activity which consequently maintained the quality of the water to match that of low-density ponds. Accordingly, these aerators could be effectively used to sustain higher yields. The effluent from the aerated pond is less likely to alter the redox balance of the receiving waters.

Redclaw crayfish, Cherax quadricarinatus, early juveniles were reared at different stocking densities in a closed recirculation system using 12-L plastic containers as rearing tanks. Initial stocking densities were 1.0, 1.5, 2.0, 2.5, and... more

Redclaw crayfish, Cherax quadricarinatus, early juveniles were reared at different stocking densities in a closed recirculation system using 12-L plastic containers as rearing tanks. Initial stocking densities were 1.0, 1.5, 2.0, 2.5, and 3.0 per liter (66, 89, 111, 133, and 156 crayfish/m2, respectively). Rearing period was 42 days. Each density was tested with five replicates. Shelter (0.112 m2) was added to double the surface area of rearing tanks. Animals were fed ad libitum twice a day with a commercial diet containing 35% crude protein. There were no significant differences (P < 0.05) in length and specific growth rate (SGR) among stocking densities. Final weight and daily weight gain, however, were significantly higher at the density of 66 per m2 (1.0 per liter). Total biomass at harvest increased with density. Survival was affected by stocking density from day 28 onward, decreasing with density from 62.7 ± 7.6% obtained at 66 crayfish/m2 to 44.85 ± 8.18% at 156 crayfish/m2.

Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different durations of culture (30, 45 and 60 days) in order to determine the growth rate... more

Kappaphycus striatum var. sacol was grown in two separate studies: (1) at two stocking densities, and (2) at four different depths, each for three different durations of culture (30, 45 and 60 days) in order to determine the growth rate of the seaweed and evaluate the carrageenan content and its molecular weight. The results demonstrated that stocking density, duration of culture and depth significantly (P K. striatum var. sacol. Decreasing growth rate was observed at both stocking densities and at four depths as duration of culture increased. A lower stocking density (500 g m−1line−1) showed a higher growth rate for the shortest durations, i.e. 30 days, as compared to those grown at a higher density. Likewise, decreasing growth rate was observed as depth increased, except at 50 cm after 60 days of culture. A 45-day culture period produced the highest molecular weight at both stocking densities (500 g m−1line−1 = 1,079.5 ± 31.8 kDa, 1,000 g m−1line−1 = 1,167 ± 270.6 kDa). ‘Sacol’ grown for 30 days at 50 cm (1,178 kDa) to 100 cm (1,200 kDa) depth showed the highest values of molecular weight of carrageenan extracted. The results suggested that K. striatum var. sacol is best grown at a stocking density of 500 g m−1line−1, at a depth of 50–100 cm, and for a duration of 30 days in order to provide the highest growth rate, carrageenan content and molecular weight.

We evaluated the performance of whiteleg shrimp Penaeus vannamei (Boone, 1931) in response to different stocking densities and acclimation periods. Shrimp postlarvae were acclimated from seawater (30 g L−1) to low-salinity well water... more

We evaluated the performance of whiteleg shrimp Penaeus vannamei (Boone, 1931) in response to different stocking densities and acclimation periods. Shrimp postlarvae were acclimated from seawater (30 g L−1) to low-salinity well water (<1.0 g L−1) at a constant hourly reduction rate of 40, 60, 80 and 100 h. After acclimation to low-salinity well water, postlarvae from each acclimation time treatment were stocked in three replicate tanks at densities of 50, 100, 150 or 200 shrimps m−2 for 12 weeks of growth. Salinity averaged <1.0 g L−1 for each growth study. The different treatments resulted in significant differences in both the final body weight and the survival rate (SR). Shrimp acclimated for 100 h showed substantially improved survival (83%) relative to shrimp acclimated for shorter periods. Shrimp yields for all cultured periods ranged from 0.32 kg m−2 in tanks stocked at 50 m−2 to 1.14 kg m−2 in tanks stocked at 200 m−2. We conclude that whiteleg shrimp can be successfully grown in low-salinity well water, and that the growth, production output and SRs are significantly higher when shrimp are acclimated for longer periods.

The Community-based Fish Culture in Seasonal Floodplains and Irrigation Systems (CBFC) project is a five year research project supported by the Challenge Program on Water and Food (CPWF), with the aim of increasing productivity of... more

The Community-based Fish Culture in Seasonal Floodplains and Irrigation Systems (CBFC) project is a five year research project supported by the Challenge Program on Water and Food (CPWF), with the aim of increasing productivity of seasonally occurring water bodies through aquaculture. The project has been implemented in Bangladesh, Cambodia, China, Mali and Vietnam, where technical and institutional options for community

Study on the effects of different stocking densities on growth, survival rate and economic return of prawns from postlarvae to juvenile stage in ponds was conducted in Tam Binh district, Vinh Long province. Experiment was designed with... more

Study on the effects of different stocking densities on growth, survival rate and economic return of prawns from postlarvae to juvenile stage in ponds was conducted in Tam Binh district, Vinh Long province. Experiment was designed with two treatments of 50 and ...

Two experiments were conducted to assess the effect of organic and inorganic fertilizers on natural food composition and performance of African catfish (Clarias gariepinus) fry produced under artificial propagation. In both experiments... more

Two experiments were conducted to assess the effect of organic and inorganic fertilizers on natural food composition and performance of African catfish (Clarias gariepinus) fry produced under artificial propagation. In both experiments chicken manure, di-ammonium phosphate and no fertilizer were used as treatments. The first experiment was conducted to determine the abundance and diversity of natural food produced in tanks fertilized with chicken manure and di-ammonium phosphate fertilizer. The second experiment was conducted to assess growth performance and survival of catfish fry produced in chicken manure and di-ammonium phosphate at 5fry/m2 and10fry/m2 stocking densities. Nine concrete tanks and eighteen concrete tanks were used in experiment 1 and 2, respectively. The results indicated that abundance of natural food (phytoplankton) were significantly higher (P<0.05) in di-ammonium phosphate (DAP) fertilizer applied tanks compared to other treatments. Zooplankton diversity was
higher in tanks applied with chicken manure, followed by tanks applied with DAP fertilizer and least in tanks with no fertilizer. Fry growth performance was higher in fertilized tanks compared to unfertilized tanks. At low stocking density (5fry/m2) fry had better growth performance compared to high stocking density (10fry/m2) across all fertilizer types. Survival rates were not significantly different (P>0.05) between chicken manure and DAP fertilized treatments across
stocking densities though significantly differed (P<0.05) from the control. Water quality parameters were found to be within the optimum range for cat fish in both experiments. In conclusion, the study indicated that higher phytoplankton abundance are attained with DAP fertilized tanks and zooplankton diversity were higher in chicken manure applied tanks. Therefore, it is recommended that for better growth and survival in aquaculture practices, catfish fry should be raised in DAP or chicken manure fertilized tanks at low stocking density as suggested by this study

A study was conducted in the Ebro valley in Spain to evaluate the utilization and intake of Atriplex halimus grazed by ewes and goats, as well as bush regrowth after 12 months of grazing. Ten Rasa Aragonesa ewes and ten Blanca Celtibérica... more

A study was conducted in the Ebro valley in Spain to evaluate the utilization and intake of Atriplex halimus grazed by ewes and goats, as well as bush regrowth after 12 months of grazing. Ten Rasa Aragonesa ewes and ten Blanca Celtibérica goats were allowed to browse an identical number (587) of A. halimus bushes for 5 weeks at a stocking density of 20 heads ha−1. Measurements were made of height (h) and width (d) of every bush before and after grazing and 12 months later to evaluate regrowth next season. Forage DM of bushes (y) was related to its volume () by the equation y(g) = 337.5 × (m3) + 162.37 (r = 0.92∗∗∗) that was used to estimate forage availability. Patterns of forage utilization were similar for goats and ewes, being 61% and 59% the level of utilization, respectively, after 4 weeks grazing. Differences in level of DM intake of goats (1430 g day−1) and ewes (1310 g day−1) were not significant. Reduction in volume of bushes consumed by goats (0.563 m3) was higher (P < 0.001) than by ewes (0.271 m3). The values appear to be associated with mean size of twigs eaten (4.58 vs 2.72 mm), used as a parameter to estimate differences in browsing ability between goats and sheep. Pregrazing plant dimensions were recovered 12 months after grazing, suggesting that A. halimus is tolerant to high grazing pressures in autumn. Browsing appeared to be mainly of annual regrowth, allowing the animals access again to the forage produced in the following season. Lack of effect on BW gain suggests that a sole diet of A. halimus may be used to maintain sheep and goats without an energy supplement until animal requirements are higher due to pregnancy and milk production.La capacidad de utilización y nivel de ingestión de Atriplex halimus por ganado ovino y caprino asi como la capacidad de rebrote del arbusto 12 meses despues del pastoreo fueron evaluados en un estudio llevado a cabo en el valle del Ebro. Se utilizaron 10 ovejas Rasa Aragonesa y 10 cabras Bianca Celtibérica que dispusieron de un mismo numero de arbustos (587) durante 5 semanas a una densidad de carga de 20 cabezas ha−1. Se tomaron medidas del diametro (d) y altura (h) de cada planta antes y despues del pastoreo y 12 meses mas tarde para valorar la capacidad de rebrote en la siguiente estación. La producción de MS forrajera de los arbustos (y) se relacionó con su volumen () mediante la ecuación, y(g) = 337.5 × (m3) + 162.37 (r = 0.92∗∗∗) que se utilizó para estimar la disponibilidad de forraje. La evolución de la utilización de los arbustos fue similar para ambas especies, resultando un nivel de utilización del 61% y del 59% para cabras y ovejas respectivamente, tras 4 semanas de pastoreo. Las diferencias en el nivel de ingestion entre cabras (1430g día−1) y ovejas (1310 g día−1) no fue significativo. La reducción del volumen de los arbustos consumidos por las cabras (0.563 m3) fue significativamente mayor (P < 0.001) que la de los consumidos por las ovejas (0.271 m3). Estos valores aparecen asociados con la sección media de los tallos consumidos (4.58 vs 0.272 mm), utilizada como un parametro para estimar diferencias en capacidad de ramoneo entre cabras y ovejas. Las dimensiones de los arbustos 12 meses despues del pastoreo sugieren que el A. halimus tolera bien elevadas presiones de pastoreo en otoño. El aprovechamiento de los arbustos, parece dirigirse principalmente hacia el rebrote anual, permitiendo el acceso de los animales al forraje producido en la siguiente estación. La falta de respuesta sobre peso vivo sugiere que el A. halimus puede ser utilizado como dieta exclusiva para mantener los animales sin necesidad de suplementación energética hasta que sus necesidades de gestación o lactación fueran mayores.Dans un étude realisé dans la vallée de l'Ebre la capacité d'utilisation et le niveau d'ingestion d'Atriplex halimus par des ovins et des caprins a étéévaluée ainsi que la capacité de repousse d'arbustre 12 mois après le pâturage. A telle fin ont été utilisés 10 ovins de la race Rasa Aragonesa et 10 chèvres de la race Blanca Celtibérica disposant du même nombre d'arbustes (587) pendant 5 semaines avec une charge de 20 animaux ha−1. Les mesures du diamètre (d) et de la hauteur (h) de chaque arbuste avant et après le pâturage et 12 mois après leur utilisation ont été prises afin d'évaluer la capacité de repousse dans la saison suivante. La production de MS de fourrage des arbustes (y) a été relationnée avec son volume () par l'équation y(g) = 337.5 × (m3) + 162.37 (r = 0.92***), utilisée pour estimer la disponibilité de fourrage. L'évolution de l'utilisation des arbustes fut similaire pour les deux espéces, avec un niveau d'utilisation du 61% et du 59% respectivement pour chévres et moutons, aprés 4 semaines de pâturage. Les différents niveaux d'ingestion entre chévres (1340 g jour−1) et moutons (1310 g jour−1) n'ont pas été pas significatifs. La reduction du volume des arbustes consommés par les chèvres (0.563 m3) a été significativement plus important (P < 0.001) que celle des arbustes consommés par les moutons (0.271 m3). Ces valeurs sont associés à la section moyenne des tiges consommees (4.58 vs 2.72) utilisées comme paramètre pour estimer les différences dans la capacité de broutage entre chèvres et moutons. Les dimensions des arbustes 12 mois après le pâturage suggérent que le A. halimus tolère bien des intensités de pâturage fortes à l'automne. L'utilisation des arbustes semble principalement orientée vers la repousse annuelle permettant l'accès des animaux au fourrage produit dans la saison suivante. Le manque d'évolution du PV suggère que l'utilisation de A. halimus peut etre exclusive sans apport de suplément energétique tant que les besoins de gestation ou de lactation des animaux ne seront plus importants.

To improve the production of Kappaphycus plantlets in tissue culture, optimum media concentrations of an Ascophyllum nodosum extract (Acadian Marine Plant Extract Powder, AMPEP), plant growth regulators (PGR), pH–temperature combinations,... more

To improve the production of Kappaphycus plantlets in tissue culture, optimum media concentrations of an Ascophyllum nodosum extract (Acadian Marine Plant Extract Powder, AMPEP), plant growth regulators (PGR), pH–temperature combinations, and explant density were determined. Kappaphycus alvarezii var. tambalang purple (PUR), kapilaran brown (KAP), vanguard brown (VAN), adik-adik (AA), tungawan green (TGR), and K. striatum var. sacol green (GS) were used as explants. Based on the shortest period for shoot emergence and the economical use of AMPEP, the optimum enriched media was 3.0 mg L−1 AMPEP and 0.1 mg L−1 AMPEP + PGR 1 mg L−1 each phenylacetic acid (PAA) and zeatin for PUR, 1.0 mg L−1 AMPEP + PGR for KAP and GS, 0.1 mg L−1 AMPEP + PGR for VAN, and 3.0 mg L−1 AMPEP and 0.001 mg L−1 AMPEP + PGR for AA and TGR. Results showed that the addition of PGR to low concentrations of AMPEP hastened shoot formation. pH–temperature combinations for the most rapid shoot formation were determined for the brown (KAP) and purple (PUR) color morphotypes of K. alvarezii var. tambalang and the green morphotype of K. striatum var. sacol (GS) cultured in 1.0 mg L−1 AMPEP + PGR. The brown morphotype produced the most number of shoots at pH 7.7 at 20°C after as little as 20 days. Purple K. alvarezii showed an increased shoot formation at pH 6.7 at 25°C and the green K. striatum morphotype at pH 8.7 at 25°C. The optimum number of explants added to the culture media was also determined for tungawan green (TGR), brown (KAP), and tambalang purple (PUR) varieties of K. alvarezii in 1.0 mg L−1 AMPEP + PGR. The number of explants and the volume of the culture media combination were also tested. The highest average number of shoots formed occurred in two explants:1 mL culture media (2:1) for KAP and PUR (35.00% and 16.67%, respectively) and 1 explant: 2 mL culture media for the TGR (100.00%) with a range of 0.5–3.0 mm shoot length after 40 days in culture. The earliest shoot formation was observed after 21 days for the brown and 9 days for both the green and purple color morphotypes of Kappaphycus, in all densities investigated. This indicated that within the range tested, the density of explants did not have a significant effect on the rate of shoot formation but did influence the average number generated from the culture. The rate of production of new and improved Kappaphycus explants for a commercial nursery stock was improved through the use of AMPEP with optimized culture media pH, temperature, and density conditions.

Effects of stocking densities on the growth, survival and production of mahseer (Tor putitora) fingerlings were examined in a single-stage nursery-rearing system. The experiment was conducted for 8 weeks in six earthen nursery ponds... more

Effects of stocking densities on the growth, survival and production of mahseer (Tor putitora) fingerlings were examined in a single-stage nursery-rearing system. The experiment was conducted for 8 weeks in six earthen nursery ponds having an area of 0.012 h each. Four-day-old hatchlings stocked at 0.6 million/ha was designated as treatment-1 (T1), 0.8 million/ha as treatment-2 (T2) and 1.0 million/ha as treatment-3 (T3). At stocking, all hatchlings were of same age group with a mean length and weight of 1.18 ± 0.04 cm and 0.012 ± 0.003 g, respectively. Hatchlings in all the treatments were fed with Saudi Bangla (SABINCO) commercial fish feed viz., nursery (32.06% crude protein) for the first 14 days and starter-I (31.53% crude protein) from days 15 to 56. Physico-chemical parameters (temperature, secchi disc transparency, dissolved oxygen, pH and total alkalinity) and plankton populations (phyto- and zooplankton) were at the optimum level for fish culture. Highest weight gain was observed in T1 and lowest in T3. Final length, final weight and survival of fingerlings also followed the same trends as weight gain. Fingerlings in T1 produced significantly higher specific growth rate than T3, but not than T2. Feed conversion ratio was significantly higher in T1 followed by T2 and T3 in that order. Significantly higher number of fingerlings was produced in T3 than in T2 and T1, respectively. Despite this, consistently higher net benefits were obtained from T1 than from T3 and T2. Overall, highest growth, survival and benefits of fingerlings were obtained at a density of 0.6 million hatchling/ha. Hence, of the three stocking densities, 0.6 million hatchling/ha appears to be the most suitable stocking density for rearing of mahseer fingerlings in single-stage nursery system.

Three potentially valuable red seaweeds, Chondrus crispus Stackhouse, Gracilaria bursa pastoris (S.G. Gmelin) P.C. Silva and Palmaria palmata (L.) O. Kuntze, collected in northern Portugal, were cultivated using the nutrient-rich... more

Three potentially valuable red seaweeds, Chondrus crispus Stackhouse, Gracilaria bursa pastoris (S.G. Gmelin) P.C. Silva and Palmaria palmata (L.) O. Kuntze, collected in northern Portugal, were cultivated using the nutrient-rich effluents from a local turbot (Scophthalmus maximus Linnaeus) and sea bass (Dicentrarchus labrax Linnaeus) farm. The algae were cultivated in a two level cascade system. Several arrangements of the cascade

The influence of genotype and stocking densities on growth performance, carcass qualities, and cost-benefits of broilers were examined in a 28-day trial. Two hundred and seven 4-week-old birds each of Anak Titan and Arbor Acre hybrid... more

The influence of genotype and stocking densities on growth performance, carcass qualities, and cost-benefits of broilers were examined in a 28-day trial. Two hundred and seven 4-week-old birds each of Anak Titan and Arbor Acre hybrid broiler types were randomly assigned to three stocking density treatments of 8.3, 11.1, and 14.3 birds/m2 in a 2 × 3 factorial arrangement. Final body weight, average weekly body weight and average weekly feed intake were affected (P < 0.05) by strain, with higher means recorded for Arbor Acres. However, average weekly body weight gain and feed conversion ratio were similar (P > 0.05) in both genetic groups. The effect of placement density on some growth parameters did not follow a linear trend. Arbor Acres had significantly (P < 0.05) higher relative (%) fasted body, carcass, back, neck, and wing weights compared to Anak Titans. Housing density effect (P < 0.05) was observed for relative (%) fasted body, shank, and wing weights of birds. However, the relative weights of visceral organs of birds were not significantly (P > 0.05) influenced by genotype and housing density. The economic analysis revealed that higher gross margin was recorded for Arbor Acres compared to Anak Titans (€2.76 versus €2.19; P < 0.05, respectively). Conversely, stocking rate did not exert any influence (P > 0.05) on profit margin. Genotype × stocking density interaction effect was significant for some of the carcass indices investigated. It is concluded that under sub-humid conditions of a tropical environment, the use of Arbor Acre genetic type as well as a placement density of 14.3 birds/m2 appeared to be more profitable.