Growth Coefficient Research Articles

Stock assessment of barred spiny eel, Macrognathus pancalus (Hamilton, 1822) in a wetland ecosystem, northwestern Bangladesh: A fundamental approach to ensure sustainability and conservation

This research delved into the management approach for Macrognathus pancalus within the Gajner Beel of northwestern Bangladesh, employing a comprehensive array of length-based indicators. The study encompassed an investigation into population structure, growth parameters (including asymptotic length (L∞), asymptotic weight (W∞), growth coefficient (K), and age at zero length (t0)), mortality parameters, growth performance indices, recruitment pattern, exploitation rate (E), relative yield per-recruit (Y'/R), optimum catchable length (Lopt), longevity, biomass, and maximum sustainable yield (MSY). The TL and BW ranged from 5.00 to 16.20 cm and 0.49 g–17.20 g for males, and 7.80–18.80 cm and 1.25–29.75 g for females. The overall b value of LWR indicated positive allometric growth for both males and females. The size at first sexual maturity (Lm) was measured 9.74 cm for males and 11.16 cm for females in TL, while calculated age at first sexual maturity (tm) (year) was 0.83 for males and 0.84 for females. The L∞ and W∞ values were determined as 17.15 cm, 23.20 g for males and 19.86 cm, 41.40 g for females. Growth performance indices for males and females were found to be 2.26 and 2.60, respectively. The longevity of males and females was estimated at 4.84 and 4.76 years, respectively. Lopt values were recorded as 9.65 for males and 11.14 cm for females. Calculated M values were 0.95 year−1 for males and 0.97 year−1 for females, while F was determined as 1.29 year−1 and 1.51 year−1 for males and females, respectively. Total mortality (Z) was found to be 2.24 year−1 and 2.48 year−1 for male and female M. pancalus populations. The E were calculated at 58% and 61%, while the MSY indicated 46% and 49%, underscoring the need for a 12% reduction in fishing pressure for both males and females to prevent overexploitation. The findings offer valuable insights for the sustainable management of M. pancalus in the Gajner Beel and its surrounding habitats, underlining the urgency of conservation efforts.

Utilization of an insect-based diet by a herbivorous fish (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus)

An 8-week feeding trial was conducted to evaluate the effect of Alates termite (Macrotermes falciger) based diet in a herbivorous (Oreochromis mossambicus) and an opportunistic predator (Clarias gariepinus). Five diets were formulated to replace fishmeal at 0, 10, 30, 50, and 70 % and were denoted D1, D2, D3, D4, and D5, respectively. Clarias gariepinus sub-adults (209.24 ± 2.41 g/fish) were stocked at 5 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Oreochromis mossambicus juveniles (7.4 ± 4.78 g/fish) were randomly stocked at 10 fish per tank in recirculating fibreglass tanks (400 L) in triplicates. Fish were fed their allocated diets, twice a day to apparent satiation. Growth performance indices (specific growth rate, thermal-unit growth coefficient) were lowest at inclusion level above 50 % in both species (P < 0.05). The nutrient utilization indices (feed intake, protein efficiency ratio) were lowest at inclusion level above 50 % in both species. The organosomatic indices (condition factor, hepato-somatic index, viscero-somatic index) were not influenced by the inclusion of Alates termite meal in both species. The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not influenced by Alates termite meal in O. mossambicus (P > 0.05). However, AST and ALT levels significantly increased at inclusion levels above 50 % in C. gariepinus (P < 0.05). The triglyceride, cholesterol, and glucose levels showed no significant difference across diets in both fish species (P > 0.05). The study showed that both species may utilize an insect-based diet up to 50 % inclusion levels without adverse effects on growth performance and nutrient utilization.

Relationships between the specific growth rate and the thermal-unit growth coefficient applied to cultured juvenile fish

The growth of cultured juvenile fish is usually quantified by two indexes, the specific growth rate or SGR, and the thermal-unit growth coefficient or TGC. The SGR is a relative growth index based on logarithms of body weights, and it decreases with body weight. The classical TGC is based on one-third powers of body weights and the summation of temperature over time. It can also depend on body weight, but it is possible to release this dependency by empirically adjusting the power function in its mathematical definition. These two indexes are usually presented in the same article to compare the growth attained by different groups of fish subjected to different experimental treatments. However, no formal framework linking both indexes is available for researchers up to the moment, the meanings of SGR and TGC remaining unrelated. The present work shows that the TGC of a group of fish growing at a given temperature can be expressed as a function of the SGR. In addition, the relationship between SGR and TGC here reported provides the basis to re-defined the TGC as a size-independent index with application to fish culture.

Population Dynamics of Gudusia chapra (Hamilton, 1822) from Lake Kaptai, Bangladesh

Aims: This study aimed to assess the population dynamics of Gudusia chapra in Lake Kaptai, Bangladesh, utilizing FiSAT II software for comprehensive analysis. The key objective was to determine growth parameters, mortality rates, exploitation status, and length-weight relationships to inform policy.&#x0D; Study Design: The study employed a quantitative approach, utilizing length frequency data collected from Lake Kaptai. FiSAT II software facilitated the estimation of population dynamics parameters, employing the Von Bertalanffy growth equation and other relevant analyses.&#x0D; Place and Duration of Study: The research was conducted in Lake Kaptai, Bangladesh, focusing on the intricate aquatic ecosystem from November 2003 to October 2004. Data collection and analysis spanned an extensive duration, providing a robust understanding of the population dynamics of G. chapra.&#x0D; Methodology: FiSAT II software was utilized for population dynamics estimation, with a particular focus on growth parameters, mortality rates, and exploitation status using Von Bertalanffy growth equation. Length-weight relationships were also determined. Recruitment patterns were observed, and key indices, including the growth performance index calculated.&#x0D; Results: The estimated asymptotic length (L∞) and growth coefficient (K) of G. chapra were found to be 19.95 cm and 0.89 year-1 respectively. Natural mortality (M), fishing mortality (F) and total mortality (Z) rates were 1.85, 2.21 and 4.06 year-1 respectively. The exploitation rate (E) indicated overfishing, with a value of 0.54, which exceeded the optimum E (E=0.5). The growth performance index (φ´) of 2.54 was recorded, and the recruitment pattern occurred between April and July.&#x0D; Conclusion: The study concludes that G. chapra in Lake Kaptai is experiencing overfishing, as indicated by the elevated exploitation rate. Understanding the growth parameters and mortality rates is vital for sustainable fisheries management in the region.&#x0D; Implication: The findings have significant implications for fisheries management, highlighting the urgent need for measures to mitigate overfishing of G. chapra in Lake Kaptai. Implementing conservation strategies and monitoring recruitment patterns are crucial for ensuring the long-term sustainability of this important fish species.

Age and growth estimates for the nurse shark (Ginglymostoma cirratum) over 17 years in Bimini, The Bahamas

Age and growth estimates are essential for life history modeling in elasmobranchs and are used to inform accurate conservation and management decisions. The nurse shark (Ginglymostoma cirratum) is abundant in coastal waters of the Atlantic Ocean, yet many aspects of their life history remain relatively understudied, aside from their reproductive behavior. We used mark-recapture data of 91 individual G. cirratum from Bimini, The Bahamas, from 2003 to 2020, to calculate von Bertalanffy (vB) growth parameters, empirical growth rate, and age derived from the resulting length-at-age estimates. The Fabens method for estimating growth from mark-recapture methods was applied through a Bayesian framework using Markov chain Monte Carlo (MCMC) methods. This provided growth parameters with an asymptotic total length (L∞) of 303.28 cm and a growth coefficient (k) of 0.04 yr-1. The average growth rate for G. cirratum was approximately 8.68 ± 6.00 cm yr-1. This study also suggests that the previous maximum age for G. cirratum is likely underestimated, with the oldest individual predicted to be 43 years old. Our study is the first to present vB growth parameters and a growth curve for G. cirratum. It indicates that this species is slow-growing and long-lived, which improves our understanding of their life history.

Risk Factors of Cardiovascular and Cerebrovascular Events in Patients With Uraemia Complicated With Hypertension During Maintenance Haemodialysis Treatment.

This study aimed to investigate the risk factors associated with major adverse cardiovascular (group of events that affect heart and blood vessels) and cerebrovascular (events affecting blood vessels supplying the brain) events (MACCE) in patients with uraemia complicated with hypertension who required maintenance haemodialysis (MHD) treatment. Clinical dataand laboratory indicators of 156 uraemia patients complicated with hypertension were collected and retrospectively analysed. The patients were admitted to a tertiary care hospital (Abbas Institute of Medical Sciences AIMS) in Muzaffarabad, Pakistan, from February 2018 to February 2022. The data was collected through consecutive sampling and patients were recruited after following the inclusion and exclusion criteria. Eighty-one out of 156 patients were not complicated with MACCE, and 75 patients were complicated with MACCE during the MHD treatment cycle, with an incidence of 48.08%. Compared to the non-MACCE group, the MACCE group's diabetes, body mass growth rate, triglyceride (TG), NT-proBNP, standard deviation and coefficient of variance for systolic and diastolic blood pressure (SBP-SD, SBP-CV, DBP-SD, and DBP-CV) showed significant differences (P<0.05) between the groups. Diabetes, body mass growth rate, TG, NT-proBNP, SBP-SD, SBP-CV, DBP-SD, and DBP-CV with odds ratios of 3.074, 3.202, 2.188, 2.512, 2.357, 2.431, 2.299, and 2.062 respectivelywere risk factors for MACCE in uraemia patients with hypertension. From the results of this study, we inferred that patients with uraemia and hypertension complicated by MACCE in the treatment cycle of MHD were related to diabetes, body mass growth rate, TG, NT-proBNP, SBP-SD, SBP-CV, DBP-SD, and DBP-CV.

Smoltification, seawater performance, and maturation in Atlantic salmon (Salmo salar) fed different fat levels

IntroductionThe use of recirculating aquaculture systems (RAS) to produce Atlantic salmon smolts has resulted in exceptionally high fish growth rates. However, there are potential negative trade-offs between fast growth and key physiological processes, such as inadequate smoltification and early sexual maturation, which can both be linked to body energy reserves.MethodsThis study determined the effect of i) dietary fat levels on Atlantic salmon whole-body fat and fatty acids composition, growth performance and smoltification and ii) a previous dietary regime on seawater growth performance and male early sexual maturation. In freshwater RAS, salmon parr (~19g) were fed 3 fat levels (20, 24, and 28%) over a 14-week period at 12°C. Subsequently, in seawater flow-through systems, smolt (~96g) were fed a control diet (26%) for 12 weeks at 2 temperatures (12 and 16°C).ResultsDietary fat levels resulted in differences in k-factor, fish whole-body fat and fatty acids composition; the low fat diet resulted in fish with a 23% lower whole-body fat when compared to the other two dietary groups at the end of the freshwater phase. These differences in whole-body fat faded at the end of the seawater phase. During the freshwater phase, all three feeds resulted in a comparable growth performance and smoltification indicator values, including k-factor, gill Na+, K+-ATPase, blood serum chloride and smolt index score. In contrast, water temperature resulted in fish body weight differences, where groups reared at 16°C were larger than those reared at 12°C. Nevertheless, both temperature regimes supported a similar thermal growth coefficient. Smolts grown at 16°C showed a higher level of the sex steroids androstenedione compared to those at 12°C. However, 11-ketotestosterone and testosterone levels did not differ despite a trend for higher levels at 16°C. Furthermore, testis histology at the final sampling indicated that some individuals showed initial signs of maturation (stage 3).DiscussionIn conclusion, varying dietary fat levels (20 - 28%) during the freshwater phase did not influence smoltification or male early sexual maturation during the subsequent grow-out phase. However, a temperature increase from 12 to 16°C resulted in larger fish and appeared to stimulate early male maturation in some fish individuals.

Stock Assessment and Virtual Population Analysis of Carassius auratus (Linnaeus, 1758) in the Al-Diwaniya River, Middle of Iraq

A total of 1128 individuals of C. auratus were collected from the Diwaniyah River, Iraq. Samples were collected between November 2016 and October 2017 using different fishing gears aiming to assess the stock assessment and virtual population analysis. Fish length ranged from 8.0 to 33.0 cm, with a length-weight relationship exhibiting positive allometric growth. Asymptotic length (L∞) was estimated at 33.0 cm, the growth coefficient (K) was 0.16, and the growth performance index (Ǿ) was 2.241. The values of total (Z), natural (M) and fishing (F) mortality rates were 0.89, 0.47, and 0.42, respectively. The exploitation rate (E) was 0.48. Length with a 50% probability of capture (LC50) was estimated at 18.7 cm and was higher than the length at first maturity (Lm50). The recruitment consisted of one seasonal pulse from April to July. The exploitation rate (E) was below the biological target reference points (E0.1 and Emax), indicating the stock was under exploitation state. The result of the virtual population analysis revealed that most of the fishing mortality happened in mid-lengths (18-26 cm) with a maximum rate at a length of 25 cm. Natural losses were highest among individuals within the length range of 8.0 to 15 cm and then decreased gradually to the length group of 30. For management purposes, this study suggests that more yields can be obtained by increasing the fishing activities on this invasive species, such as increasing the number of fishing boats and decreasing the mesh size to decline its abundance in the long term.

Comparative Study on the Effects of Four Plant Protein Sources on the Liver and Intestinal Health of Largemouth Bass, Micropterus salmoides.

The effects of plant protein sources (PPSs) on the health of the liver and intestine of the largemouth bass, Micropterus salmoides, were compared to verify the potential damaging effects of dietary fiber (DF). A diet containing 55% fish meal (FM) was used as the control. The test diets contained 25% soybean meal (SBM), rapeseed meal (RSM), cottonseed meal, or peanut meal, and the FM content was decreased to 30%. The protein and lipid contents of these five diets were balanced by casein and oil. Fish were raised for 8 weeks. The fish fed the diet containing PPS showed a trend of decreasing growth and apparent digestibility coefficients. The contents of total bile acid, lipid, and collagen in the liver were increased, and the mRNA expression levels of genes encoding inflammatory factors and enzymes involved in de novo fatty acid synthesis and bile acid synthesis were upregulated. Both the lipid and collagen contents in the liver were positively correlated with the DF content in the diet significantly. Morphology and histology showed reduced liver size, hepatic steatosis, and fibrosis in fish fed diets containing PPS. The lowest hepatosomatic index was observed in fish fed the SBM diet, and the most severe damage was observed in fish fed the RSM diet. No obvious histological abnormalities were observed in the hindgut. The bile acid profile in the liver could be used to distinguish the types of PPS very well by Fisher discriminant analysis. These results indicated that 25% of each of the four PPSs in the diet exceeded the tolerance range of largemouth bass and caused liver damage, which might be mediated by bile acid. DF in PPS might be an important agent contributing to liver damage.

In situ experimental investigation of fiber orientation kinetics during uniaxial extensional flow of polymer composites

The demand for fiber-filled polymers has witnessed a significant upswing in recent years. A comprehensive understanding of the local fiber orientation is imperative to accurately predict the mechanical properties of fiber-filled products. In this study, we experimentally investigated the fiber orientation kinetics in uniaxial extensional flows. For this, we equipped a rheometer with a Sentmanat extensional measurement device and with an optical train that allows us to measure the fiber orientation in situ during uniaxial extension using small angle light scattering. We investigated an experimental system with glass fibers for the suspended phase (L/D=8−15), and for the matrix either low density polyethylene, which shows strain hardening in extension, or linear low density polyethylene, which shows no strain hardening. For these two polymer matrices, the fiber orientation kinetics were investigated as a function of fiber volume fraction (ϕ=1%, 5%, and 10%) and Weissenberg number (by varying the Hencky strain rate, ϵ˙H=0.01−1s−1). We found that all these parameters did not influence the fiber orientation kinetics in uniaxial extension and that these kinetics can be described by a multiparticle model, based on Jeffery’s equation for single particles. Our results show that, in uniaxial extension, fiber orientation is solely determined by the applied strain and that, up to the concentrated regime (ϕ≈D/L), fiber-fiber interactions do not influence the fiber orientation. The extensional stress growth coefficient of these composites, which is measured simultaneously with the orientation, shows high agreement with Batchelor’s equation for rodlike suspensions.

Weak approximation schemes for SDEs with super-linearly growing coefficients

We propose a new class of weak approximation schemes for stochastic differential equations with coefficients of suplinearly growth. Both the modified weak Euler schemes and the drift-implicit weak Euler scheme are studied. Under certain non-globally Lipschitz conditions, the proposed schemes are proved to have first-order convergence in the weak sense. Numerical experiments are included to confirm the theoretical results.

Age, growth, reproduction and mortality of Xenocypris argentea (Günther,1868) in the lower reaches of the Tangwang River, China.

To investigate various population biological parameters of Xenocypris argentea in the lower reaches of the Tangwang River (China), a comprehensive study was conducted for the first time. A total of 1,003 samples were collected from April to November 2022. The collected samples revealed that female X. argentea had total lengths ranging from 12.4 cm to 25.7 cm (weighing 15.86 g to 159.55 g), and male X. argentea had total lengths ranging from 10.8 cm to 23.9 cm (weighing 9.27 g to 121.06 g). The age of the samples was determined using otolith analysis, indicating that the ages ranged from 1 to 5 years old in both females and males. The length-weight relationships were further analyzed, uncovering the allometric growth index (b) was 3.1296 for females, indicating a positive allometric growth pattern. Differently, males exhibited a b value of 3.0274, suggesting an isometric growth pattern. Furthermore, the von Bertalanffy growth formula provided insights into the growth characteristics of X. argentea, revealing an asymptotic total length (L∞) of 36.096 cm and a growth coefficient (K) of 0.121. The analysis of the gonadal somatic index (GSI) and ovarian development period indicated that the spawning period occurred from April to July, with peak spawning in June. The study also explored fecundity-related traits, finding that individual absolute fecundity (FA) ranged from 11,364 eggs to 56,377 eggs, while eviscerated body weight relative fecundity (FW) ranged from 209 eggs/g to 823 eggs/g. The exploitation rate (E) for X. argentea was calculated as 0.574, suggesting that the population of X. argentea has been overexploited. By revealing previously unknown data on the key life history traits of X. argentea, this study has provided valuable insights that are crucial for the development of conservation strategies and policies.

Length-based growth, mortality, and biological reference points of Chrysichthys nigrodigitatus (Lacepède, 1803) from the Yeji arm of Lake Volta, Ghana

Individuals of Chrysichthys nigrodigitatus from Lake Volta, Ghana (West Africa), were examined between January and December 2020 for growth, mortality, and exploitation rate using total length measurement. Monthly length-frequency data were collected from 244 samples and analysed using the FiSAT II Tool. The estimated asymptotic total length (L∞), the coefficient of growth (K), and the calculated growth performance index (phi) were 27.3 cm, 0.57, and 2.63 pear year, respectively. The total mortality rate (Z), natural mortality rate (M), and fishing mortality rate (F) were 1.57, 0.92, and 0.66 pear year, respectively. The exploitation rate (E = 0.42) was below the optimum level of 0.5, which indicates that the species is underexploited. Based on the Emsy (0.56) value, analyses show that the exploitation rate is below the sustainable limit, hence the need for continuous monitoring of fishing efforts to ensure that the limit reference point is not exceeded.

Model of biodiversity and plant sustainability based on quantum variational optimization

Plant biodiversity plays an important role in the sustainability of ecosystems and human societies. The resilience of plants in the context of biodiversity relates to their ability to adapt to changing environmental conditions, provide ecosystem services and meet human needs. This article examines the influence of quantum variational optimization on the solution of a system of differential equations for a model of plant biodiversity and sustainability, taking into account the interaction between two populations. The system of equations models the dynamics of changes in the density of plant populations of types and over time, consider the influence of interaction, growth coefficients and the intensity of the impact of diseases and pests. The numerical integration method is used to solve the system of equations, and quantum variational optimization is also introduced. Quantum variational optimization is performed with the goal of minimizing the error obtained from a quantum computational experiment. An analysis is made of the optimal parameters found using quantum optimization and their impact on population dynamics. The article provides a comprehensive approach to studying the influence of quantum variational optimization on the solution of differential equations, and discusses the potential prospects for using this method in environmental and biological models.

On the government revenue on economic growth of Sub-Saharan Africa: Does institutional quality matter?

As studies report inconclusive results, the linkage between government revenue and economic growth remains a topic of debate in economic literature. This study investigates the effect of government revenue on the economic growth of Sub-Saharan African countries with the main objective of whether institutional quality matters. The panel data for 43 SSA countries were obtained from dependable data sources: World Development Indicator and Heritage Economic Freedom Index for the period of 2012–2022. The result from system GMM estimation reveals that government revenue adversely affects economic growth while institutional quality positively enhances economic growth before interacting with each other. However, the interactive coefficient of government revenue and economic growth positively affected the real GDP growth rate of SSA countries over the study periods. Precisely, before interacting with institutional quality, a percentage change in government revenue, keeping all other things constant, leads to a 0.0866% decline in economic growth while it marks a 0.2329% upsurge in economic growth in the presence of institutional quality. The result of the study further revealed that government revenue promotes the economic growth of the region when combined with institutional quality. On the other hand, foreign direct investment and openness to trade were the key sources of economic growth whereas the population growth rate adversely impacted economic growth in SSA countries during the study period under consideration. The policy implication of the study is that SSA needs to strengthen government revenue management. Further, the finding of the study implies that SSA countries need to improve institutional quality through promoting efficiency of the regulatory quality and the size of the SSA governments. In addition to this, the fast real GDP growth rate of SSA countries demands improved institutional quality indicators such as the rule of law and extended access to the open market.

Impact of fishing activities on the population dynamics of European whitefish in four peri-alpine lakes

Inland fisheries play a crucial role in socio-economic activities and food production. However, these fisheries are often less intensively monitored and studied than marine fisheries. In the past two decades, important fluctuations in European whitefish (Coregonus lavaretus) landings have been observed in four peri-alpine lakes in France and Switzerland. To better gauge the impact of fishing removal, a multi-lakes Delay-Difference model was developed and adapted to these fisheries. A hierarchical state-space Bayesian framework was used to integrate stochasticity for each process and incorporate diverse data. The model gave estimates of time series for biomass, recruitment, stage-structured landings, and fishing mortality, as well as estimates of natural mortality rate, Brody growth coefficient and mean recruitment productivity. Differences in the estimates of variables predicted by the model were observed among lakes. Negative impacts of exploitation have been highlighted for Lakes Geneva, Bourget, and Annecy. Low levels of biomass under high fishing mortality rates were observed, while landings tended to increase under lower mortality rates. Lakes Geneva and Bourget outputs suggest stocks were impacted by fishing activities and that fishing effort reduction could ultimately increase yields. Lake Annecy abundance and landings trends increased after 2010, suggesting management strategies that focused on effort reduction were successful. Lake Neuchâtel stock abundance was low after 2017 and probably more fragile due to low biomass levels and recruitment. The observed changes in European whitefish biomass cannot be attributed solely to fishing, suggesting that environmental factors may also influence recruitment success alongside the impacts of fishing pressure.

Synchronous magnetization to weaken the hindrance of surfactants to droplet coalescence during electric dehydration

Electric dehydration is the most widely used physical technology for separating water from crude oil. However, natural surfactants stabilize the oil–water interface, resulting in low dehydration efficiency and failure of the electric dehydrator due to electric field collapse. To explore the physical methods of weakening the influence of surfactants on electric dehydration, this study synchronously increased magnetization during the electric dehydration. Based on high-speed microscopy experiments, it has been demonstrated that synchronous magnetization weakens the hindrance of surfactants to droplet coalescence during electric dehydration. Within the experimental conditions, the influence of magnetization on the growth coefficient C1 ranges from 2.9% to 26.6%. In addition, based on molecular dynamics simulation, the mechanism of magnetization weakening the influence of surfactants was studied at the molecular level. It was found that water molecules and surfactant molecules undergo significant molecular clusters after magnetization, reducing the influence degree of surfactants on unit area. When the surfactant concentration increases, the decrease in the influence degree is balanced by the increase in the number of molecules, which also explains the law that the improvement rate ΔC1 decreases with the increase in surfactant concentration. The results of this work will be potentially valuable for weakening surfactant barriers to demulsification and oil–water separation.

Realization of reproductive qualities of cows and productivity of young stock.

For the first time, on the basis of complex research, scientifically based and experimentally proven zootechnical feasibility of using the Prevention-N-A biologics developed by us based on the polysaccharide complex of yeast cells Saccharomyces cerevisiae and the aminoglycoside group bactericidal preparation in the technology of obtaining and growing calves in comparison with the previously approved PS-2 preparation. It is proved that three-time intramuscular injection of PS-2 and Prevention-N-A biologics to down-calvers 45-40, 25-20 and 15-10 days before calving in a dose of 10 ml prevents gynecological diseases and increases reproductive function. Under the influence of preparations in cows, the time of separation of the fetal membranes was reduced by 6.0 and 6.4 hours, retention of placenta, post-parturient complications and breast diseases were prevented. The risk of subinvolution of the uterus and endometritis in the first case decreased by 3.0 and 2.0 times, respectively, and in the second - was excluded (P<0.05). Against the background of immunocorrection in cows, the time of onset of heat by 11.6 and 14.2 days, the insemination index by 1.6 and 1.8 times, the service period by 22.4 and 28.4 days, and fertilization in 1 oestrus increased by 2.5 and 3.0 times (P<0.05-0.01). It was found that twice intramuscular injection of PS-2 and Prevention-N-A to calves on 2...3rd and 7... 9th day of life in a dose of 3 ml stimulates their growth and development, reduces the incidence. By the end of the growing period, the animals of the 1st and 2nd experimental groups were superior in live weight to control peers by 4.6 and 7.0 kg, rearing - 13.8 and 17.0 kg, and fattening - by 19.4 and 24.2 kg, respectively (P<0.05-0.01). A similar pattern occurred in the nature of changes in exterior measurements and the growth coefficient of animals of the compared groups. In calves of the experimental groups, the incidence of respiratory and digestive organs decreased by 2.3 and 7.0 times, the recovery time - by 1.3 and 4.3 days, respectively, compared to the control (P<0.05).

Population Dynamics of Indian Makerel (Rastrelliger kanagurta) in Northern Bone Bay Waters, Indonesia

This study aims to analyze the parameters of Rastralliger kanagurta population dynamics in the waters of Northern Bone Bay. To analyze the parameters of population dynamics, measurements were made of the total length of the sample fish in centimeters. The research was conducted in March – September 2022 at the Palopo City Pontap Fish Landing Site. Sampling is carried out every two weeks. The results of the growth parameter analysis obtained each value of growth coefficient = 0.84 per year, asymptotic length = 30.5 cm and to = -0.189 years. Furthermore, for mortality parameters, natural mortality was obtained at 1.64 per year, capture mortality = 2.47 per year, and total mortality at 4.11 peryear and exploitation rate at 0.6%. The results show that the growth rate of Rastralliger kanagurta is very high and can reach maximum length at a relative age of 15 years. Mortality parameters show that Rastralliger kanagurta mortality in northern Bone Bay waters is higher from fishing than natural mortality. The exploitation Rastralliger kanagurta in the waters of northern Bone Bay is 60% greater than the maximum exploitation rate of 50%. Based on the results of this study, management of fishery resources is needed so that the population is not disturbed.

Effect of hot-electron preheating on the multimode bubble-front growth of the ablative Rayleigh–Taylor instability

Hot electrons (HEs) generated via parametric instabilities at high laser intensities are a critical concern of laser-driven inertial confinement fusion (ICF), which can significantly impact the ICF performance by preheating the target. In this paper, the effects of HE preheating with moderate HE energy on the evolution of two-dimensional multimode ablative Rayleigh–Taylor instability (ARTI) up to the self-similar growth stage are studied through numerical simulations with a multigroup diffusion model. It is found that HE preheating stabilizes the linear growth of multimode ARTI and delays the onset of the self-similar growth regime. This time delay is more significant for the short-wavelength mode ARTI and higher energy HE cases. It is also shown that the variation of self-similar growth coefficients under HE preheating is not very significant. The delay to the onset of the nonlinear stage of multimode ARTI by HE preheating with moderate energy may be beneficial to ICF implosions.