Cage Density Research Articles

Development of innovative scorecard for assessment of welfare and production performance of commercial layer birds reared at different stocking densities in cages

A methodology to assess the welfare of laying birds maintained in cages was developed using innovative scorecardmethod without compromising the production and economics in Indian scenario. To develop scorecard, specific keyparameters such as production, economics, egg quality, welfare and behaviour were considered. The scores for these key parameters were assigned on the basis of the performance of the commercial laying hens maintained in different stocking densities in cages (387, 484, 548 and 645 cm2/b) for an experimental period of 20 weeks. The range for each parameter was decided and based on it four groups were formed and the treatment with the best performance received the highest weightage, that is how scoring of each treatment was done according to the range they fitted in. The scoring, weightage and guidelines were devised by Delphi technique, by a panel of national experts from the academics and experts working in the poultry industry. At the end of the experimental period, laying birds maintained at stocking density of 548 cm2/b scored the highest weightage with 84 out of total 100; 48 weightage for production and economics, 12 weightage for egg quality and 40 weightage for welfare and behaviour. From all above results, it could be summarized that this innovative scorecard can be used to determine the best performance of laying birds taking welfare into consideration.

Production Performance of Layer Strain Hy-Line Brown in Different Cage Locations in Closed House

The aim of this study was to determine the production performance of layer hen strain Hy-Line Brown in different cage locations in closed house. The research material was 5,051 laying hens of the Hy-Line strain aged 28 weeks. House system was closed house, cage arranged to form frame A. Hy-Line Brown layer were housed at cage densities of 500 cm2 per hen. Research feed is complete feed code 324 KJ produced by PT. Charoen Pokphand Indonesia. The research method is comparative, comparing the production performance on the location of the cage in zone 1 (inlet), zone 2 (middle), and zone 3 (outlet) of a closed cage. The research sample is 10% of the total population. Observations were carried out on 6 cages which were randomly selected in each cage zone. The average density of cages is 20 birds/m2. Tabulated research data are Hen Day Production (%), egg weight (g), egg mass (kg), and feed conversion. Data analysis is analysis of variance analysis (One-Way ANOVA). Based on the results of the study, there were significant differences in the the production performance of layer hen strain Hy-Line Brown in different cage locations in closed house. The highest production performance is the cage located close to the inlet (Zone 1).

Comparison of performance parameters, stress, and immunity levels of native and commercial layers reared in different cage densities in Turkey

In this study, production performance, stress, and immunity levels of native Turkish and imported commercial laying hens were investigated in two different cage densities. In the trial, a total of 06 groups were formed by using two different cage densities (312.50 and 468.75 cm$^{2}$/hen) on each of 03 different laying hen hybrids of Isa Brown (IB), Atak-S (A-S) and Novogen White (NW). The trial was carried out with 09 replicates in each group having 10 birds per replicate making 540 birds in total. Water and feed were provided as ad libitum. It was found that the native hybrid showed lower performance in comparison to the foreign hybrids in terms of production performance such as egg production (EP), feed consumption (FC) and feed conversion ratio (FCR) (p < 0.01), while its growth variables such as livability (L) and body weight (BW) were higher. In terms of stress and immunity levels, the native hybrid showed similar values to those of the brown foreign hybrid, while the stress levels were lower and immunity levels were higher in the white laying hens (p < 0.001). It was observed that the yield characteristics and stress levels were affected negatively in higher cage density (p < 0.01), while immunity levels were not affected (p > 0.05). It was concluded that the yield characteristics of the native hybrid were relatively lower in comparison to those of the foreign hybrids, while its stress and immunity levels were similar, and cage density decreased yield, increased stress and did not significantly affect immunity levels.

PERTUMBUHAN BURUNG PUYUH (COTURNIX COTURNIX JAPONICA) UMUR 3 MINGGU DENGAN PERBEDAAN KEPADATAN DI DALAM KANDANG

The purpose of this study was to determine the growth of quail aged 3 weeks, based on different cage densities. Completely randomized design was used during the study, with the density of quails in cages were 11 (P1), 13 (P2), 16 (P3), and 20 (P4). The results showed that differences in quail density in cages affected (P0.05) body weight, consumption, and conversion of quail during rearing. the number of quail in the cage is 11 for a cage size of 35x30x40 cm. Body weight, consumption, and conversion of feed produced at 3 weeks of age were: 95.52 gr, 12.53 gr, 0.13

Clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion: comparisons between unilateral and bilateral cage insertion

BackgroundAlthough the original technique involves inserting two cages bilaterally, there could be situations that only allow for insertion of one cage unilaterally. However, only a few studies have compared the outcomes between unilateral and bilateral cage insertion. The purpose of this study was to compare the clinical and radiological outcomes in patients who underwent posterior lumbar interbody fusion (PLIF) between unilaterally and bilaterally inserted cages.MethodsAmong 206 eligible patients who underwent 1- or 2-level PLIF, 78 patients were 1:3 cohort-matched by age, sex, and operation level (group U, 19 patients with unilateral cages; and group B, 57 patients with bilateral cages). Fusion status was evaluated by computed tomography (CT) scans at postoperative 1 year. Clinical outcomes were measured by visual analog scale (VAS), Oswestry Disability Index (ODI), and EQ-5D. Radiological and clinical parameters were compared between the two groups. Risk factors for pseudarthrosis were also analyzed by multivariate analysis.ResultsThe demographic data were not significantly different between the two groups. However, previous laminectomy, asymmetric disc collapse, and fusion at L5-S1 level were more frequently found in group U (P = 0.003, P = 0.014, and P = 0.014, respectively). Furthermore, pseudarthrosis was more frequently observed in group U (36.8%) than in group B (7.0%) (P = 0.004). Back pain VAS was higher in group U at postoperative 1 year (P = 0.033). Lower general activity function of EQ-5D was observed in group U at postoperative 1 year (P = 0.035). Older age (P = 0.028), unilateral cage (P = 0.007), and higher bone mineral density (P = 0.033) were positively correlated with pseudarthrosis.ConclusionsUnilaterally inserted cage might be a possible risk factor for pseudarthrosis when performing PLIF, which could be related with the difficult working conditions such as scars due to previous laminectomy or asymmetric disc collapse. Furthermore, suboptimal clinical outcomes are expected following PLIF with unilateral cage insertion at postoperative 1 year regardless of similar clinical outcomes at postoperative 2 year. Therefore, caution is advised when inserting cages unilaterally, especially under above-mentioned conditions in terms of its possible relationship with symptomatic pseudarthrosis.

Performance Of Nile Tilapia Oreochromisniloticus (L) In Cages of Varied Stocking Densities

Cage culture is a new venture in Tanzania, and the knowledge of stocking density in cages is still needed. Growth performance of Nile tilapia, Oreochromis niloticus (L) stocked in cages of varied stocking densities and their impacts on waters were evaluated for 212 days in Shirati Bay of Lake Victoria. We started with fingerlings of 18.0±2.1 g, 19.9±14.7 g, and 18.5 ± 8.0 g mean weights. They were raised in cages at stocking densities of 70 (Treatment I), 100 (Treatment II), and 130 fish/ m3 (Treatment III) each in triplicates. We recorded monthly fish weights and lengths, total nitrogen, total phosphorus, ammonia, and micro-benthos. Parameter such as dissolved oxygen, pH, temperature, and transparency were all monitored weekly. The final average fish weights were 374.1±59.8g in treatment I, (194.8 ± 63.7g) in II, and (273.2±20.6g) in III. Percentage fish survival was the highest in treatment I (76.7%), followed by II (65.4%) and III (54.3%). Specific growth rate, production and yield was the highest in treatment I, and significantly different from treatments II and III (p &lt;0.05). This indicates that Nile tilapia flourished well in the lowest stocking density. Water quality parameters were within the range of fish culture throughout the study and observation of water depth, distance from the shoreline, and the prevailing water currents showed lack of adverse environmental effect caused by fish cage culturing

Effects of Stocking Density in Group Cages on Egg Production, Profitability, and Aggressive Pecking of Hens

ABSTRACT There is an increasing concern about welfare issues related to battery cages, which are commonly used in Vietnam, and requires a modified cage that improves hen welfare while retaining its economic and management advantages. We combined adjacent conventional cages to form group cages to examine the effects of stocking density on egg production, economic returns, and aggressive pecking of hens. The control group included triplicate conventional cages with four birds/single cage (12 hens per three cages) or 450 cm2 area per hen. Three group cage treatments were set up with 10, 12, and 14 birds per group cage or 540, 450, and 386 cm2 of floor area per hen, respectively. Compared to 14 birds per cage, hens housed at 10 birds per group cage had a higher hen-day production, consumed less feed, and thus had a better feed conversion ratio/dozen eggs. Reducing the stocking density to 10 birds per group cage resulted in additional production cost, but it was compensated for by a high egg income, and significantly decreased aggressive pecks. Group cages benefit hen performance, profitability, and welfare when decreasing the stocking density to 10 birds per cage with 540 cm2/hen.

Serum clinical biochemical markers of Hy-Line W-36 laying hens under the influence of increased stocking densities in cages of multilevel batteries

Today, the organism of hens is constantly exposed to numerous technological stressors in the conditions of industrial poultry farming, the least studied of which are long-term, which can cause the development of chronic stress. One of such stressors is the increased stocking density of hens, which is also a way of saving resources in egg poultry and is often used by producers to obtain more eggs per 1 m2 of poultry area. The aim of this study was to examine the effect of overcrowding, as a factor of chronic stress development, on the body of hens of a modern high-performance cross, which is necessary to select the best ways to keep them. Four groups of hens were formed for this purpose, which were kept at different stocking densities, according to European standards, Ukrainian standards and with increasing overcrowding. In this way, the gradually increasing intensity of the technological stressor was modeled. Long-term keeping of laying hens at high stocking density did not affect the content in the serum of total protein, albumin, urea and cholesterol, which were within the physiological norm. It was found that the increase in the stocking density of hens to Ukrainian standards, compared to the European, was accompanied by an increase in the activity of lactate dehydrogenase in the serum of their blood. With an increase in stocking density above European and Ukrainian standards, namely to 25.3 birds/m2, there was an increase in the activity of three enzymes – lactate dehydrogenase, aspartate aminotransferase and gamma-glutamyltransferase. It is proved that further overcompaction of hens to 26.7 birds/m2 is accompanied by an increase in serum glucose, creatinine, as well as a decrease in the ratio of calcium and phosphorus, which was confirmed by an increase in alkaline phosphatase activity. Also, increased activity of aspartate aminotransferase, lactate dehydrogenase and gamma-glutamyltransferase was observed. Thus, the main effects of chronic stress caused by prolonged keeping of hens at high stocking densities are reflected in the biochemical parameters of their serum, namely in the increase of glucose, creatinine, enzyme activity, as well as the violation of the ratio of calcium and phosphorus.

Effect of cage density on growth rate, carcass traits, muscle amino acid profile, and antioxidant biomarkers of commercial rabbits.

The objective of this work was to elucidate the impact of cage density on growth efficiency, carcass yield, and muscle amino acid profile of fattening rabbits. In total, 96 weaned rabbits were assigned into three cage densities: low cage density (LCD) = 1425 cm2/rabbit; medium cage density (MCD) = 850 cm2/rabbit; high cage density (HCD) = 625 cm2/rabbit. Compared with the HCD, the body gain and feed conversion ratio were better in the LCD and MCD groups (P = 0.003 and 0.004, respectively). The MCD and HCD groups had lower hot carcass weight (P = 0.012) and dressing percentage (P = 0.022) than the LCD group. Compared with the HCD group, the LCD and MCD groups exhibited greater serum GSH (P = 0.029) and SOD (P = 0.032), but significantly lower levels of serum cortisol and cholesterol (P = 0.001 and 0.026, respectively). Regarding the amino acid profile of longissimus dorsi and leg muscles, the LCD group had significantly higher levels of muscle lysine and threonine than the HCD and MCD groups (P˂0.05). The current study indicates that the MCD (850 cm2/rabbit) could maintain an acceptable growth performance, carcass traits, and welfare-related parameters. Furthermore, only the low cage density (1425 cm2/rabbit) may preserve the levels of essential (lysine, isoleucine, and threonine) and nonessential (histidine, proline, and glysein) amino acids in the longissimus dorsi and leg muscles of growing rabbits.

Molecular characterization of polyOAPS-imide isomer hyper-cross-linked membranes: Free-volume morphologies and sorption isotherms for CH4 and CO2

PolyPOSS-imides are hybrid hyper-cross-linked networks based on inorganic octa(aminopropyl)silsesquioxane (POSS) cages covalently bonded via organic imide bridges. They were initially developed for separations under harsh conditions, but they cannot be used above 300 °C due to the decomposition of their –(CH2)3– propyl linkers. Replacing the aliphatic-arm POSS with its phenyl-arm derivative, octa(aminophenyl)silsesquioxane (OAPS), should thus increase their resistance. However, OAPS has three possible isomers depending on the meta, para or ortho position of the –NH2 group on the phenyl ring. To pre-screen the most interesting structures before attempting synthesis, molecular dynamics (MD) simulations were recently used to compare twenty-two model networks based on the OAPS isomers, the initial POSS and several imide precursors at high temperatures. Six phenyl-arm polyOAPS-PMDA and polyOAPS-6FDA and two aliphatic-arm polyPOSS-PMDA and polyPOSS-6FDA were selected for further analyses of their CH4 and CO2 sorption isotherms at 35 °C. All of them have an average number of ~5 links per cage and cross-linking densities of ~3.8. In terms of connectivities and free-volume morphologies, both the metaOAPS and paraOAPS networks are found to be open structures with many low-energy sites and high penetrant solubilities. On the other hand, the ortho functionalization leads to denser morphologies associated to lower solubilities, which makes it closer to the POSS networks. Differences are enhanced when the inorganic precursor is associated to a rigid organic linker such as PMDA.The iterative GCMC (Grand Canonical Monte Carlo)-MD sorption-relaxation technique was used to predict the single-gas uptakes of CH4 and CO2 in the networks over an extended 0–60 bar pressure range at 35 °C. The sorption capacities varied in the order paraOAPS > metaOAPS > orthoOAPS > POSS for the inorganic precursor, and PMDA > 6FDA for the organic precursor (except for the orthoOAPS). All correlate directly to the accessible free-volume, but the CO2/CH4 ideal sorption selectivities remained essentially the same over the whole pressure range. Compared to POSS, OAPS showed less swelling at equivalent penetrant concentrations in the matrix. It is also more resistant to other mechanical deformations such as isotropic dilation or uniaxial tension. This confirms that the polyOAPS-imides can indeed be used under harsher conditions than the current polyPOSS-imides, without loss of the CO2/CH4 sorption selectivities.

PRODUKTIVITAS PEMELIHARAAN AYAM BROILER DI KAMPUNG BEBANIR BANGUN KECAMATAN SAMBALIUNG

The research aims to determine the productivity of broiler chickens' maintenance in broiler breeder business with a partnership pattern in Sei Bebanir Bangun Village, Sambaliung District, Berau Regency. This research was conducted for two months, from October to December 2016. The research method was quantitative descriptive. Data collection techniques with purposive sampling with census sampling. Data analysis using Microsoft Excel and mathematical calculations. The results showed that data on cage density were density &lt;10 heads of chicken/m2, ± 10 head of chicken/m2, and&gt; 15 heads of chicken/m2. Chicken mortality is still high, more than 1%, the lowest is at a density of ± 10 heads of chicken/m2, at 2.69 heads of chickens/m2. Production at a density of &lt;10 heads of chicken/m2 with an average weight of 1.71 kg, at a density±10 heads of chickens/m2 with an average weight of 1.80 kg, and at a density of&gt;15 head/ m2 with an average weight of 1.81 kg. At densities&gt;15 heads of chicken/m2, it is more efficient in using a cage but has higher mortality than those with densities &lt;10 heads of chicken/m2, ± 10 heads of chicken/m2

Effects of Laboratory Housing Conditions on Core Temperature and Locomotor Activity in Mice.

Drug developers worldwide assess compound safety and efficacy using measures that include mouse core temperature and locomotor activity. Subtle differences in animal housing conditions between institutions can alter these values, impacting scientific rigor and reproducibility. In these studies, adult male NIH Swiss mice were surgically implanted with radiotelemetry probes that simultaneously monitored core temperature and locomotor activity across various housing conditions. In the first study, ambient temperature was varied between 20 °C and 28°C in groups of singly housed mice. Additional studies held the mice at a constant ambient temperature and examined the effects of cage density (housing animals singly or in groups of 3 or 6), bedding change and provision of nesting material, and the availability of a running wheel on core temperature and locomotor activity. Mice overwhelmingly maintained species-typical core temperatures across all ambient temperatures, across all housing conditions, when bedding was fresh or old, and with or without the provision of cotton squares as nesting material. However, engaging in wheel running and the combination of fresh bedding and cotton squares transiently increased core temperatures beyond the species-typical range. Similarly, the circadian distribution of locomotor activity was significantly disrupted by placing animals in cages with fresh bedding or nesting material, or by performing both of these manipulations concurrently during the light period. These findings suggest that standard husbandry practices and common housing conditions may transiently affect core temperature in adult mice. Furthermore, these practices may have profound and relatively long-lasting effects on motor activity and the regulation of circadian rhythms.

Effect of stocking density on performance, meat quality and cecal bacterial communities of yellow feather broilers

Totally, 315 42-day-old male Xueshan chickens were allocated into 3 caging densities, 14, 21 and 28 birds/m2. Each treatment was represented by 5 replicates. The body weight (BW), slaughter performance, meat quality, behavioral assessment, and the cecal microorganisms were detected at the market age. The results showed that the BW of broilers in the low- and medium-density groups was significantly higher (p < 0.05) than that of the high-density group from the age of 10 weeks. Only the feather quality of the broilers in the low-density group improved significantly (p < 0.05) compared with those of the other two groups. And, the abdominal fat percentage and the fat content of thigh muscle of broilers in the low- and medium-density groups were higher (p < 0.05) than those in the high-density group. No significant difference (p > 0.05) was noted in the other traits. The abundance of some microbial like Akkermansiaceae, Lactobacillaceae and Faecalibacterium may be correlated with the BW and fat content of broilers. The findings of this study suggest that increasing the stocking density decreased the final BW, fat content and the feather quality, whereas no evidence was found that stocking density caused changes in other parameters.

Aktivitas Antioksidan, Kadar Serat dan Karakteristik Fisik Beras Hitam Pecah Kulit Pratanak dengan Variasi Lama Waktu Perendaman

Black rice has a better bioactive component than white rice. The quality of black rice can be increased, among others, through the process of the broken skin grinding . B lack br oken r ice has a better nutritional and bioactive component than polished rice. But b lack b roken rice skin is easily damaged. One that can be done is processing into parboiled rice. The purpose of this study in general was to determine antioxidant activity, fiber content and the characteristics of black rice broken pre pared skin. The experimental design used was a monofactor Completely Randomized Design (RAL) with variations in the length of immersion time (0, 30, 60, 90, 120, 150 and 180 minutes). Analysis was carried out on antioxidants, fiber content and physical characteristics (cage density, air absorbency, development ratio, bulk angle and broken grain) black broken rice skin with parboiled. The results of the study stated that the treatment of soaking black rice caused a decrease in antioxidant activity and crude fiber. The highest decreased in the 180 minutes immersion treatment with a decrease in presentation was 35% and 10,2% respectively, the results of testing on physical characteristics showed immersion treatment had an effect on decreasing in the kamba density test, development ratio, bulk angle and broken grain. However, the water absorption test experienced an increase. The best treatment is in a variation of 30 minutes soaking time.

Effect of oregano (Oreganum syriacum L.) essential oil and cage density on performance parameters, egg quality criteria, some blood biochemical parameters, blood antioxidant capacity, and intestinal histopathology in laying hens

Although many methods have been developed in order to reduce the negative effects in laying hens reared at high cage density, researches on effects of dietary supplementation of oregano (Oreganum syriacum L., OEO) essential oil as a feed additive to the diets are extremely sparse. This study investigated the effects of OEO and caging density on performance parameters, egg quality criteria, some blood biochemical parameters, blood antioxidant capacity, and intestinal histopathology of laying hens. We used 276 white Lohmann laying hens aged 38–40 weeks in the experiment. The animals were divided to positive control (600 cm2 hen/cage, PC), negative control (360 cm2 hen/cage, NC), negative control+ 200 mg/kg OEO (NC+O2), negative control+ 400 mg/kg OEO (NC+O4), and negative control+ 600 mg/kg OEO (NC+O6). In this study, it was determined that egg weight and egg shell weight increased at higher caging density, but they did not change with dietary supplementation of OEO. In addition, the plasma calcium and phosphorus decreased with the higher caging density and dietary supplementation of OEO. Supplemented OEO to the diets of the laying hens reduced lipid peroxidation and improved antioxidant capacity and intestinal histopathology of laying hens. As a result, it was determined that OEO decreased the negative effects of high caging density. While this positive effect was found to be at a maximum dose at 400 mg/kg of OEO, it was determined that a dose of 600 mg/kg of OEO had a toxic effect, if even numerically.

Strong effects of a mutualism on freshwater community structure.

Numerous mutualisms have been described from terrestrial and marine communities and many of these mutualisms have significant effects on community structure and function. In contrast, there are far fewer examples of mutualisms from freshwater habitats and there is no evidence that any mutualism has community-wide or ecosystem-level consequences. Northern hemisphere crayfish are host to a variety of ectosymbiotic worms called branchiobdellidans. The association between some of these "crayfish worms" and their hosts is a mutualism. The outcome of the association is context dependent and can be influenced by host size, symbiont number, and the environment. Here we document in two experiments that the mutualism between crayfish and these worms alters the effect of crayfish on stream community structure and sediment deposition, an important ecosystem variable. We enclosed crayfish stocked with 0 worms and intermediate (3-6) and high worm densities (12) in cages in streams in Boone, North Carolina and Clemson, South Carolina, United States. At both locations, there was a negative relationship between initial worm density and final macroinvertebrate abundance. There was a significant effect of worm treatment on macroinvertebrate community structure in both the Boone and Clemson experiments. In Boone, there were effects on both overall macroinvertebrate abundance and community composition, whereas in Clemson, changes to community structure were primarily driven by changes in total abundance. There was a negative relationship between benthic sediment volume and initial worm density in both experiments, primarily later in the experiments, though these effects were influenced by sediment deposition rates. Our results are the first to demonstrate strong effects of a mutualism on freshwater communities. Both members of this mutualism are found throughout the northern hemisphere, so similar impacts may occur in many other waterways. Given that various species in addition to crayfish function as keystone species and ecosystem engineers in freshwater systems throughout the world, mutualisms involving these strongly interacting species may be as important to the structure and functioning of freshwater systems as comparable mutualisms in marine and terrestrial systems.

Histological and ultrastructural changes in turkey liver under intensive rear-ing and influence of xenobiotics

Liver problems of various etiologies in turkeys have been reported in many countries for the last 20 years. Poultry dies having no clinical manifestations of the disease, and at pathological autopsy, diffuse haemorrhages and marked dystrophic changes of the organ are noted. To date, there are several factors that can cause such changes, these are unbalanced amino-acid feed, insufficient calcium, biotin, selenium, the very high energy content of feed; zootechnical factors – limited mobility of birds due to cage density violations, high temperature; genetic factors – the influence of estrogens; infectious factors – E. coli, Clostridium, and viruses of Picornaviridae family. The article describes the histopathological and ultrastructural changes in the turkey liver under the influence of various factors. The material for the research was obtained from a farm where turkeys of the “Hybrid Converter” cross are grown, same age, fed with a standard diet that changed according to the technological map of cultivation. On the 50th day of life, a pathological autopsy of the dead poultry was performed, pieces of liver were selected for histological and ultrastructural examination. The visual assessment revealed significantly enlarged liver, the colour from dark red to light brown, flabby consistency. In some cases, diffuse fatty infiltrations of hepatocytes were histologically revealed, in other cases, focal necrosis with the growth of the connective tissue and the formation of massive perivascular couplings were registered. Large vacuolar fatty degeneration of hepatocytes with subsequent development of fibrosis indicates chronic intoxication, probably caused by slow breakdown of fatty acids in cells due to insufficient oxidative phosphorylation, as well as reduced levels of lipotropic factors: choline, methionine and the vitamins. At the ultrastructural level, a large number of lipid inclusions of various sizes, dystrophic changes in mitochondria were observed, which indicates a decrease in the synthetic activity of cells.

Prevention not cure: a review of methods to avoid sea lice infestations in salmon aquaculture

AbstractThe Atlantic salmon aquaculture industry still struggles with ectoparasitic sea lice despite decades of research and development invested into louse removal methods. In contrast, methods to prevent infestations before they occur have received relatively little research effort, yet may offer key benefits over treatment‐focused methods. Here, we summarise the range of potential and existing preventative methods, conduct a meta‐analysis of studies trialling the efficacy of existing preventative methods and discuss the rationale for a shift to the prevention‐focused louse management paradigm. Barrier technologies that minimise host–parasite encounter rates provide the greatest protection against lice, with a weighted median 76% reduction in infestation density in cages with plankton mesh ‘snorkels’ or ‘skirts’, and up to a 100% reduction for fully enclosed cages. Other methods such as geographic spatiotemporal management, manipulation of swimming depth, functional feeds, repellents and host cue masking can drive smaller reductions that may be additive when used in combination with barrier technologies. Finally, ongoing development of louse‐resistant salmon lineages may lead to long‐term improvements if genetic gain is maintained, while the development of an effective vaccine remains a key target. Preventative methods emphasise host resistance traits while simultaneously reducing host–parasite encounters. Effective implementation has the potential to dramatically reduce the need for delousing and thus improve fish welfare, productivity and sustainability in louse‐prone salmon farming regions.

Fluorescence indices of dissolved organic matter as early warning signals of fish farming impacts in a large tropical reservoir

Abstract Dissolved organic matter (DOM) can be an important source of energy and nutrients in aquatic ecosystems and play important roles in carbon and nutrient dynamics of natural and impacted environments. In order to assess the effects of early stage fish farming on dissolved organic carbon (DOC) concentrations as well as DOM fluorescence indices, we took water samples along transects from six fish farms towards reference sites in a large tropical reservoir (Furnas Reservoir, Southeast Brazil) between April 2013 and December 2016. While DOC concentrations did no change along transects, small but significant changes in fluorescence indices were detectable in up to 100 m from fish farms. Higher fluorescence index (FI) values near fish farms pointed to small increases in microbial production due to fish farming. Only in the more pristine of the two main reservoir branches, small differences in the freshness index (β:α) and the peak T/peak C ratio along transects indicated that the relative contribution of recently produced DOM and the biochemical oxygen demand of DOM increased due to aquaculture. The humification index did not respond to fish farming. In summary, current early-stage fish farming did not appear to cause major impacts on DOM quantity and quality, but future increases in net cage and fish farm densities, as well as longer operation times may change this assessment. The fluorescence indices FI, β:α and peak T/peak C ratio may be useful early warning signals for monitoring fish farm impacts in tropical reservoirs.

PENGARUH KEPADATAN KANDANG TERHADAP KONSUMSI RANSUM, PERTAMBAHAN BERAT TUBUH, DAN KONVERSI RANSUM BROILER UMUR 14-28 HARI DI CLOSED HOUSE

This research aimed : 1) to investigate the effect of stocking density on feed consumption, body weight gain, and feed conversion rate of broiler aged 14—28 days in closed house; 2) to determaine the best stocking density on feed consumption, body weight gain, and feed conversion ratio of broiler aged 14—28 days in closed house. This research was conducted in closed house of PT. Charoen Pokphand (Kandang Bandara 2) located in Bangun Sari area of Way Sari village, Natar district, South Lampung regency. This research was conducted for 28 days, with rearing broiler from day 1st—13th was without treatment, and then from day 14th—harvest with treatments, that was conducted in April 2019—May 2019. This research used completely randomized design with 4 treatments (15, 17, 19, and 21 stocking density of chickens m-2) and 5 replications. Data obtained was analyzed using analysis on variance at 5% levels of significance and followed by Duncan’s Multiple Range Test. Results showed that different stocking density of 15, 17, 19, and 21 chickens m-2 affected (P&lt;0.05) on feed consumption (with feed consumption of broiler of stocking density of 15 chickens m-2 was significantly (P&lt;0.05) lower than those of 17, 19, and 21 chickens m-2), but it did not affect (P&gt;0.05) on body weight gain and feed conversion ratio of broiler in closed house.&#x0D; &#x0D; Keywords: Body weight gain, Closed house, Feed consumption, Feed convertion rate, Cage density