Effects of stocking density on growth and skin quality of grower Nile crocodiles (Crocodylus niloticus)

Intensive Nile crocodile (Crocodylus niloticus) farming operates with considerable variation in housing and stocking density. In this study, current commercial stocking densities for crocodilians were investigated using 261 grower-phase crocodiles (15 months old, average total body length 94.5 cm, and average weight 2.7 kg). Low (2.60 m2 per crocodile), medium (1.24 m2 per crocodile), and high (0.41 m2 per crocodile) stocking densities were tested. Growth, morphometric measures, Fulton’s condition scores and skin qualities were assessed over a six-month (May - November 2017) period. High stocking density had no adverse effects on the growth of grower Nile crocodiles. Crocodiles stocked at medium and high densities outperformed those that were stocked at low density in Fulton’s body condition scores, change in body condition from the start to the end of the trial, and feed conversion efficiencies. However, the high and, to a lesser extent, the medium stocking densities resulted in lower skin quality scores compared with those in the low-density treatment because of teeth marks from more aggressive behaviour. The results indicated that the medium pen density treatment is closer to the ideal than either the high or low stocking density groups. Stocking densities that provide 0.41 m2 per crocodile or less should be avoided because of lower skin quality scores, which weigh more heavily than growth and feed efficiency responses in the financial viability of commercial crocodile farming in typical South African production systems.

Bone deleterious effects of different nrtis in treatment-naïve HIV patients after 12 and 48 weeks of treatment

Background: Bone alterations have been observed in the course of HIV infection, characterized by a marked decrease in bone mineral density (BMD) and an increase in the frequency of fractures as a result of fragility. We aim to evaluate early changes in bone metabolic profile and the possible association with tenofovir and other nucleoside and nucleotide reverse transcriptase inhibitors (NRTIs) in treatment-naïve HIV patients. Methods: We conducted a prospective study in naïve HIV infected adults (under 50 years), separated into three groups according to NRTI therapy: tenofovir disoproxil fumarate (TDF); tenofovir alafenamide (TAF) and abacavir (ABC). BMD and epidemiological, immunological and metabolic bone parameters were evaluated. Bone markers were analyzed in plasma at baseline, 12 and 48 weeks after initiating treatment. Results: Average age of patients was 34.8 years (± 9.6). 92.4% of them with CD4 count > 200 cel/μL. At week 12 after starting treatment, both TDF [increase in PN1P (31.7%, p = 0.004), TRAP (11.1%, p = 0.003), OPN (19.3%, p = 0.045) and OC (38.6%, p = 0.001); decrease in OPG (-23.4%, p = 0.003)] and TAF [increase in 42.6% for CTX (p = 0.011), 27.3% for OC (p = 0.001) and 21% for TRAP (p = 0.008); decrease in OPG (-28.8%, p = 0.049)] presented a deep resorption profile compared to ABC, these differences in bone molecular markers, a tendency to equalize at week 48, where no significant differences were observed. Patients treated with TDF showed the greatest decrease in Z-score in both lumbar spine (LS) and femoral neck (FN) at week 48 without statistically significant differences. Conclusions: Treatment-naïve HIV patients have a high prevalence of low bone density. Treatment with TDF is associated with greater bone deterioration at 12 and 48 weeks. TAF seems to present similar early bone deterioration at 12 weeks which disappears at 48 weeks.

Investigating sea urchin densities critical to macroalgal control on degraded coral reefs

Summary There is an assumption that tropical sea urchins are macroalgal grazers with the ability to control macroalgal expansion on degraded coral reefs. We surveyed abundances of Echinothrix calamaris, an urchin species common in the western Indian Ocean on 21 reefs of the inner Seychelles and predicted their density using habitat predictors in a modelling approach. Urchin densities were greatest on patch reef habitat types and declined with increasing macroalgal cover. Next, we experimentally investigated the macroalgae-urchin relationship by penning two sea urchin densities on macroalgal fields. Over six weeks, the highest density treatment (4.44 urchins m−2) cleared 13% of macroalgal cover. This moderate impact leads us to conclude that controlling macroalgal expansion is not likely to be one of the main functions of E. calamaris in the inner Seychelles given the current densities we found in our surveys (mean: 0.02 urchins m−2, maximum: 0.16 urchins m−2).

Metarhizium brunneum Petch Fungi is Effective as a Bioinsecticide Against Coptotermes curvignathus Holmgren Termite Pests in the Laboratory

Nutmeg is a plantation crop and has high economic value. Currently, the cultivation of nutmeg is experiencing many obstacles. One of them is termite pests. So far, the control is carried out using chemical insecticides and hurts the environment. Therefore it is necessary to control other environmentally friendly ways, and one of them is by using the fungi M. brunneum as an ecologically friendly bioinsecticide. The purpose of this study was to analyze the effectiveness of M. brunneum as a bioinsecticide against the termite C. curvignathus as an essential pest in nutmeg plantations. This research using a completely randomized design (CRD). The results showed that the mean percentage viability of M. brunneum conidia at each observation time was classified as useful. The germination of conidia increased to 89.78 % after 72 hours of observation. Conidia density 103/ mL distilled water. The highest mortality rate of C. curvignathus was found at a density of 1010 conidia/ mL of distilled water. The mean time of death for C. curvignathus after application of conidia density treatment of 1010/ mL of distilled water was 2.15 days and the death of C. curvignathus was 3.35 days using conidia density treatment 103/ mL of distilled water. 1 day after application reaches 33.20 % and increases to observation at 5 days after application reaches 100 %. The highest food inhibition occurred in treatment 1010/ mL distilled water (65.81 %) which was significantly different from treatment 105/ mL distilled water (43.23 %), and 103/ mL distilled water (41.61 %) and control (0.00).Abstrak: Pala merupakan tanaman perkebunan dan bernilai ekonomi tinggi. Pada saat ini budidayanya mengalami banyak hambatan. Satu diantaranya adalah serangan hama rayap. Selama ini pengendalian hama rayap dilakukan dengan menggunakan insektisida kimia dan berpengaruh negatif terhadap lingkungan. Oleh karenanya perlu pengendalian cara lain yang ramah lingkungan dan satu diantaranya dengan menggunakan cendawan M. brunneum sebagai bioinsektisida yang ramah lingkungan. Tujuan dari penelitian ini adalah menganalisis efektivitas M. brunneum sebagai bioinsektisida terhadap hama rayap C. curvignathus. Penelitian ini dilaksanakan di Laboratorium Hama Tanaman dan Laboratorium Dasar Proteksi Tanaman Program Studi Proteksi Tanaman Fakultas Pertanian Universitas Syiah Kuala, sejak bulan Februari hingga September 2018, dengan menggunakan Rancangan Acak Lengkap (RAL). Hasil penelitian menunjukkan bahwa persentase viabilitas rata-rata dari konidia M. brunneum pada setiap waktu pengamatan tergolong efektif. Perkecambahan konidia semakin meningkat hingga mencapai 89,78 % setelah diamati pada jam yang ke 72. Rata-rata waktu kematian rayap C. curvignathus setelah aplikasi perlakuan kerapatan konidia 1010/ mL akuades adalah 2,15 hari dan terjadi kematian rayap C. curvignathus 3.35 hari dengan menggunakan perlakuan kerapatan konidia 103/ mL akuades. Rata-rata mortalitas tertinggi rayap C. curvignathus ditemukan pada perlakuan kerapatan konidia 1010/mL aquades. 1 HSA mencapai 33,20% dan meningkat hingga pengamatan pada 5 HSA mencapai 100%. Daya hambat makan tertinggi terjadi pada perlakuan 1010/ mL aquades (65,81%) yang berbeda nyata dengan perlakuan 105/mL aquades (43,23%) dan 103/ mL aquades (41,61%) serta kontrol (0,00%).

Application of Doehlert design for optimization of the electroflotation method for the treatment of wastewater from poultry slaughtering and processing

In this work, an electroflotation (EF) method for the treatment of poultry slaughterhouse effluent was proposed, and its efficiency in reducing chemical oxygen demand (COD) was investigated. The following operating conditions were optimized through Doehlert design: [Al2(SO4)3], pH, treatment time, and current density. Treatment of the effluent was carried out in a reactor with TiO2–RuO2 (anode) and iron (cathode) electrodes. The optimum process conditions were obtained with a pH 9, current density of 60 A m–2, electrolysis time of 80 min, and [Al2(SO4)3] of 1.8 mg L–1. Under these operating conditions, turbidity, COD, and biochemical oxygen demand (BOD) removal efficiencies of 93.1%, 80.7%, and 89.7%, respectively, were obtained. The operating cost of the process was calculated at 0.9 USD per m³. The EF method combined with chemical coagulation was shown to be a suitable process for the treatment of effluent from the slaughter and processing of poultry.

The effect of Elymus nutans sowing density on soil reinforcement and slope stabilization properties of vegetation–concrete structures

Elymus nutans is an herbaceous plant that can be used to restore degraded alpine and subalpine ecosystems. Here, we evaluated how sowing density affects soil reinforcement and slope stabilization properties of vegetation–concrete structures. To investigate the optimal sowing density of E. nutans in vegetation–concrete applications for slope protection, six experimental treatments were established with different plant densities: control, I (1100 seeds/m2), II (2200 seeds/m2), III (3300 seeds/m2), IV (4400 seeds/m2), and V (5500 seeds/m2). Several parameters of plant growth in addition to soil reinforcement and slope stabilization properties were measured in each treatment, as well as the associations among parameters. As density increased, aboveground biomass continually increased, and plant heights, root surface areas, root lengths, and underground biomass all first increased and then decreased. In contrast, tiller numbers and the average root diameter gradually decreased with increasing density. Increased density also resulted in increased maximum water interception levels by aboveground stems and leaves. The maximum water interception by the aboveground stems and leaves was 41.75% greater in the highest density treatment (V) compared to the lowest density treatment (I). However, the enhancement of erosion resistance and soil shear strength first increased and then decreased as density increased, with maximal values observed in the medium-high density treatment (IV). Sowing density was highly correlated with aboveground biomass, plant heights, tiller numbers, and the maximum level of water interception by stems and leaves. Thus, sowing density directly influenced soil reinforcement and slope stabilization properties of aboveground plant components. However, density was not significantly correlated with belowground biomass, root lengths, root surface areas, the enhancement of erosion resistance, and soil shear strengths. Therefore, sowing density indirectly influenced soil reinforcement and slope stabilization of belowground plant components. Following from these results, we suggest that the optimal sowing density of E. nutans is approximately 4400 plants/m2 in their application within vegetation–concrete structures used for slope protection.

Development of Redwood Regeneration after Conifer Partial Harvest and Hardwood Management

Harvesting of commercial conifer species from conifer-hardwood mixtures can leave residual stands dominated by hardwoods. Removing unwanted hardwoods by cutting or herbicide makes growing space available to residual trees and regeneration and can restore conifer dominance. Forest managers of north coastal California need guidance on how such treatments affect subsequent growth of planted redwoods (Sequoia sempervirens [D. Don.] Endl.) or natural regeneration, as well as proliferation of undesirable species. Our observational study reconstructed growth of 108 regenerating redwoods in 26 treated stands. Residual stand density was the main driver of height and diameter growth in the new cohort of redwoods, irrespective of whether hardwoods were cut or received herbicide frill treatment (prevents resprouting). At lower residual stand densities, there were higher densities of natural regeneration (ingrowth) of conifers and hardwoods, which affected diameter at breast height (dbh) growth of regenerating redwoods. After heavier cutting of hardwoods, this ingrowth comprised a greater proportion of unwanted hardwood regeneration. Therefore, frill treatment is recommended when the objective of management is to reduce hardwood stocking and regeneration. Combining partial harvesting of conifers with cutting or frill treatment of hardwood is another option that reduces stand density to promote height and dbh growth of regenerating redwoods. Study Implications Redwood is a valuable commercial species in California Coast Range forests, but its regeneration often competes with unwanted hardwoods. The most influential solution is reducing stand density. Treatment choice is less influential, giving managers some flexibility. For example, stand density can be reduced by cutting a mix of conifers and hardwoods, or by herbicide frill treatment of hardwoods to release conifers, or some combination of these two treatments. After cutting, hardwoods resprout, leading to higher hardwood densities in the understory and slightly slower regeneration of redwood. Conversely, herbicide frill treatment promotes conifer dominance by removing hardwood trees and regeneration.

Masculinization of Tropical Eel Anguilla bicolor McClelland in Different Population Density

In general, female eel dominates the results of catching eel in the river. Male fish dare rarely found in nature, therefore masculinization is necessary for obtaining in males. The administration of 17α-methyltestosterone to masculinize Anguilla bicolor McClelland. It is a synthetic anabolic-androgenic steroid which has potential to endocrine disrupter that disturbed function of normal reproduction in human or animal. It urgently needed that a masculinization technique needs to study the use of an environmental factor. Population density is one of the environmental factors that influence gender determination (ESD-environmental dependent sex determination). This will result in increased cortisol secretion, which will further stimulate the synthesis of 11-KT steroids that affect male gonad differentiation. This study aims to induce masculinization in tropical eel Anguilla bicolor McClelland in different density. Three treatments and three replicates conducted the research. The treatments were one fish.48 L-1, two fish.48 L-1 and three fish.48 L-1. Eels size was approximately similar, at 16,78 g±0,62 in weight, and 25,38 cm±0,15 in length were either culture in brackish water for eight weeks. The results showed that density population treatment significantly increased the Fin Index (P<0.05), but no sign for Eye Index, GSI, HSI, and testosterone level. The highest male population (77,8%) achieves at the highest density treatment, three fish.48 L-1 population density. It can be concluded, based on reproductive observations, population density does not affect gonad maturity/puberty, but the high population density (3 fish.48 L-1)stimulates Anguilla bicolor McClelland masculinization.