Stocking Density Research Articles

Expression pattern of the fused in sarcoma gene and its contextual influence on the density-specific response of the growth hormone/insulin-like growth factor 1 axis in zig-zag eels (Mastacembelus armatus)

The fused in sarcoma (FUS) protein is a DNA/RNA binding protein from the ten-eleven translocation protein family that is associated with neurodegeneration, and it has been shown to promote cell proliferation through the growth hormone/insulin-like growth factor 1 (Gh/Igf-1) signaling pathway. The zig-zag eel (Mastacembelus armatus) is a newly discovered species exhibiting sexual dimorphism in growth, and the potential role of fus in the growth and development of this species remains largely unknown. Herein, we analyzed the homology, conserved domains, evolutionary characteristics, and conserved syntenies of fus in several teleost species. The expression of fus was predominant in the brain and exhibited sexual dimorphism in the brain, muscle, and liver of zig-zag eels. We found that microRNA (miR)-146-5p, miR-489-3p, and 24 other miRNAs were targeted to the fus 3′ untranslated region, which might affect muscle and bone development in adults. The igf1, insulin-like growth factor 1 receptor a (igf1ra), insulin-like growth factor 2 receptor (igf2r), growth hormone-releasing hormone-like receptor (ghrhrl), growth hormone secretagogue receptor type 1 (ghsr), and glucocorticoid receptor (gr) genes contained a higher abundance of GU-rich fus motifs compared to the other four genes analyzed in zig-zag eels. We also measured the expression of fus mRNA during fish culture at various stocking densities to further elucidate the relationship between fus expression and the Gh/Igf-1 axis. After 100 days of fish cultivation, the expression of fus and ghrhrl decreased and the expression of ghrh and gr increased as the culture density increased (p < 0.05). The expression of fus exhibited a remarkable positive correlation with a specific growth rate. These results indicate that fus mediates growth differences by regulating the expression of several growth-related genes including Gh/Igf-1 axis genes in zig-zag eels.

Bio-Organic Inputs, Height of Tier and Stocking Density: Their Effects on the Production Performance and Egg Quality of HISEX Layer Chicken

The objective of this study was to examine the impact of using natural bio-organic supplements, varying cage heights, and different stocking densities on the egg-laying performance and egg quality of layer chickens at the Poultry Project for Layer Chicken of JRMSU- Tampilisan Campus in Zamboanga del Norte. The study involved 162 eight-month-old layer chickens divided into six groups and replicated thrice. These chickens were housed in cages of different heights and stocking densities to evaluate their impact on egg production and quality. The results demonstrated that providing chickens with fermented plant juice in their water, derived from madre de agua (Trichanthera gigantea), significantly influenced egg weight and resulted in higher returns above feed and supplement costs. Furthermore, maintaining the cages at a height of 3 feet proved optimal for egg weight. The number of birds in a cage also played a significant role, with four birds per cage affecting egg production and feed and water intake. Interestingly, cages housing three birds exhibited the best feed conversion ratio. Regarding egg quality, the natural supplements did not yield significant differences, but cage height influenced the weight of the eggshells, favoring the 3-foot height. Moreover, the number of birds in a cage impacted the thickness of the yolk. Overall, the study underscored the crucial role of natural supplements, cage height, and stocking density in achieving optimal egg production and quality from layer chickens.

511 Assessing the carry-over effects of precision livestock technology on steer performance and carcass characteristics

Abstract Our objective was to evaluate how virtual fencing grazing management during the stocker phase influences steer growth performance, carcass traits, and enteric emissions during the finishing phase. Angus steers [n = 96; initial body weight (BW) = 375 ± 7.2 kg) grazed native rangeland from 07 June 2023 to 31 August 2023 in Cottonwood, SD at South Dakota State University’s Cottonwood Field Station. Following summer grazing, steers were transported to Brookings, SD and fed for 130-d at the South Dakota State University Cow-Calf Education and Research Facility. During the summer grazing season, steers were assigned to different stocking rates (Light, Moderate, and Heavy, at 0.32, 0.42, and 0.72 animal unit months, respectively), and grazing strategies [continuous (CG) or virtual fencing rotational (RG)] in a 2 × 3 factorial design. Steers were transitioned from a 30% roughage to a 10% roughage diet over 21-d. The finishing diet (13.7% CP, 17.2% NDF, 1.36 Mcal/kg NEg, and 30 g/907-kg monensin sodium) was manufactured twice daily and provided ad libitum. Feed consumption was tracked using precision monitoring equipment (Insentec, The Hague, Netherlands). Steers were individually weighed on d 1 (entry BW), 21, 63, 90, and 130 and administered a steroidal implant (200 mg trenbolone acetate and 20 mg estradiol; Revalor-200, Merck Animal Health, DeSoto, KS) on d 21. Enteric emissions, including methane and carbon dioxide, were monitored using the GreenFeed trailer system (C-Lock Inc., Rapid City, SD), growth performance, carcass traits, and categorical carcass traits were analyzed in a factorial design using a randomized complete block design with individual steer considered the experimental unit. Final BW was determined from hot carcass weight divided by 0.625. Steers from heavy-CG had greater feedlot entry BW (P ≤ 0.05) compared with all treatments except light-CG and light-RG. Light-CG and light-RG had greater entry BW compared with heavy-RG (P ≤ 0.05). Gain efficiency was greater for light-CG compared with light-RG, moderate-CG, and heavy-CG (P ≤ 0.05), while moderate-RG and heavy-RG were intermediate (P ≤ 0.05). Steers from moderate-RG had greater marbling scores compared with heavy-RG (P = 0.05), and all other treatments were intermediate. Neither stocking density (P ≥ 0.15) nor grazing management strategy (P ≥ 0.13) had any influence on other measures of growth performance, emissions (CH4 and CO2) production rate, or carcass traits. These findings suggest that stocking density and grazing-management strategy (CG vs. virtual fencing-RG) influence gains on pasture and alter feedlot entry BW, highlighting the need for further investigation into their implications for greenhouse gas emissions, as well as for determining optimal stocking densities and management strategies for ranchers

Pilot-scale investigation of an advanced biofloc technology for treating Pacific white shrimp effluent: Performance and insight mechanisms

Biofloc technology (BFT) is extensively used in the treatment of water quality in intensive shrimp aquaculture systems. However, the rapid accumulation of biofloc in middle-to-late culture stages poses challenges for system management, impacting the economic yield of aquaculture operations. To address this issue, an advanced biofloc system (A-BS) that integrates a moving bed biofilm reactor (MBBR) with BFT was constructed, and the biofloc system (BS) was used as a control group. During a 100-day pilot-scale operation, the A-BS group effectively regulated water quality and enhanced the growth rate of Pacific white shrimp (Litopenaeus vannamei). In the A-BS group, the average concentrations of ammonia, nitrite, chemical oxygen demand, and mixed liquor suspended solids were substantially reduced compared to those in the BS group, measuring 0.19, 0.55, 36.36, and 229 mg/L, respectively, across the middle-to-late culture stages. Notably, the final stocking density and survival rate of shrimp in the A-BS group, reached 7.04 kg/m3 and 81.22 %, surpassing those in the BFT group. Furthermore, microbial community and functional gene analyses revealed more in-depth insights into the related mechanisms. Bacterial abundance and diversity, as well as the presence of denitrification genes such as Unclassified_f_Rhodobacteraceae and Paracoccus, were markedly higher in the A-BS group than in the BS group. The integration of MBBR into A-BS significantly increased the abundance of amoA and nirK genes, which are crucial for water quality stability during later culture stages. This proof-of-concept investigation confirms that the MBBR–BFT coupling process in A-BS holds promise for advancing sustainable aquaculture practice and provides strategic guidance for the modernization of the industry.

Applying equineRSU and seasonal livestock correction to wider equine stud farm types

ABSTRACT To adjust for potential overestimations in the nitrogen excretion by horses within Overseer®, a revised stock unit system has been proposed (equineRSU). These equineRSU were generated and validated using a medium-sized equine farm as a model farm. The aim of this study was to test the application of the equineRSU and seasonal stock number adjustment on a more complex farming model. Livestock numbers and management data were captured prospectively for the base property (128.8 ha) of a large multi-property commercial breeding stud (3 support properties, 556 ha total area) between June 2022 and May 2023. The monthly on-farm metabolisable energy (ME) requirement and pasture demand were deterministically modelled with both a customised feed budget using livestock class and weight or using the equineRSU and monthly adjusted stock numbers. There were multiple complex movements of horses on and off the property in the different stock classes across the year, with stock management reflecting seasonal periods of high stocking density. There was good agreement (6% variance) between actual ME demand (complex feed budget) and estimated feed demand (simplistic equineRSU model) of 4,387,187 MJ vs 4,102,770 MJ. This suggests that the equineRSU could be used on complex equine farm systems within Overseer®.

Influence of stocking density and interaction variability on disease progression of white spot syndrome virus-infected shrimp under different risk scenarios

White spot syndrome virus (WSSV), the causative agent of white spot disease (WSD), is the most significant viral pathogen affecting farmed shrimp. As the culture model for whiteleg shrimp has evolved into a higher-intensity model, the need to study the influence of stocking density on disease progression in pond culture systems has been reinforced. Therefore, we assessed WSD progression by deriving a direct correlation between seasonal disease outbreak risk, stocking density, and viral shedding rate (WSSV genome copies/L/g) using three different stocking densities: high (210 shrimp/m2), medium (140 shrimp/m2), and low (70 shrimp/m2). In Experiment 1 (three stocking densities at 25 °C) and Experiment 2 (stocking density × temperature conditions), shrimp showed relatively high cumulative mortality within the temperature range of optimal WSSV replication (23–29 °C). Notably, the mortality trend, peak viral loads, and viral shedding of WSSV-infected shrimp occurred earlier under high-density conditions, regardless of temperature. Thereafter, this study established WSD risk scenarios based on water temperature conditions and confirmed a significant difference in mortality trends between vulnerable and less vulnerable water temperature scenarios under high- and low-density conditions. The vulnerable water temperature scenario included constant (25 °C), shifting-up (20 °C to 30 °C), and shifting-down (30 °C to 20 °C) conditions, whereas the less vulnerable water temperature scenario included constant 20 °C and 30 °C conditions. Based on mortality trends, the WSD risk scenarios revealed that the times to 50 % mortality for shrimp at high, medium, and low densities were 4, 5, and 6 days post-infection (dpi) in the vulnerable water temperature scenario, and 6, 7, and 9 dpi in the less vulnerable water temperature scenario. Viral shedding variability was evaluated based on the correlation between viral loads and viral shedding rate, and linear regression analysis revealed a significant positive correlation between viral shedding rates and viral loads in shrimp, regardless of WSD risk scenarios or stocking density conditions. Notably, a relatively enhanced viral shedding rate was observed at higher stocking densities (from low- to high-density conditions) and under vulnerable water temperature scenarios. This study suggests that increased stocking density and vulnerable water temperature scenarios could induce greater interactions among WSSV-infected shrimp. It also confirmed the potential role of risk scenarios, stocking density, and viral shedding in WSD progression, providing insights into the disease outbreak mechanisms on shrimp farms.

Productivity and competitive dominance of freshwater filamentous macroalgal cultivars for nutrient bioremediation of primary municipal wastewater

ABSTRACT Algal bioremediation using macroalgae is a promising approach to wastewater treatment. This study compared the productivity and bioremediation performance of the freshwater filamentous algal cultivars; Klebsormidium flaccidum, Oedogonium calcareum, and Oedogonium sp., in primary municipal wastewater in outdoor high-rate filamentous algal pond mesocosms. K. flaccidum had the highest biomass productivity (3.09 g dry weight m−2 day−1 ± 0.20 SE) and bioremediation performance, reducing total ammoniacal-N by 51% to 14.80 mg L−1 (± 0.81 SE), nitrate-N by 59% to 0.30 mg L−1 (± 0.02 SE), and dissolved reactive phosphorous by 15% to 3.52 mg L−1 (± 0.07 SE). This cultivar achieved the greatest reductions in total suspended solids (54%), carbonaceous biochemical oxygen demand (93%), and chemical oxygen demand (74%). K. flaccidum and Oedogonium sp. reduced Escherichia coli by 98%. Competitive dominance of K. flaccidum and Oedogonium sp. was assessed in bicultures at three stocking densities. By day 12, K. flaccidum's proportion increased from 50 to 64% (± 6.1 SE) and 73% (± 5.0 SE) at a stocking density of 0.25 g and 0.5 g FW L−1, respectively. Based on superior biomass productivity, bioremediation performance, and competitive dominance, K. flaccidum was identified as a target cultivar for bioremediation of primary municipal wastewater.

Culture Feasibility, Domestication and Breeding Potentiality of Penaeus indicus in the Southwest Region of Bangladesh

A preliminary observation was conducted on the culture potentiality, domestication at different stocking density and breeding competency of Chaka chingri (Penaeus indicus) in southwest region of Bangladesh from February to May in 2020 on Shrimp Research Station, Bagerhat for 120 days. There were three treatments with three replication of each where stocking density varied. Among the treatments, T3 (200 nos./dec) was found more suitable with higher growth than T2 (300 nos./dec) and T1 (400 nos./dec). In regular samples of wild Chaka taken from the regions of Bagerhat, Satkhira, and Khulna, histological investigation revealed that no oocyte was discovered during the reproductive period. The explanations for why the right big shrimp could not be located. Since P. indicus needs more salinity and profundity for the growth of gonadal tissue, the ecological conditions were similarly unfavorable. In this instance, the areas that have greater salinities and shrimp of a reasonable size ought to be chosen for a breeding program. After analysis, the approximate composition of P. indicus's flesh and shell was discovered to be below average. It's because P. indicus experiences prolonged stress and an adverse body condition due to reduced salinity, which has a significant impact on feeding and growth rates along with the rate at which dietary protein is converted to meat protein. Consequently, the current study suggests carrying out a breeding program and preserving the ideal natural conditions for Chaka chingri adaptation.

Social interactions of dairy cows and their association with milk yield and somatic cell count

The social environment experienced by livestock can have implications for their health, welfare, and subsequently, their productivity. Changes in the dairy industry have led to larger herd sizes and altered management of cows, which has impacted their social environment. Studies have shown that mixing of animals can lead to social instability of groups and expansion of herds can lead to high stocking densities resulting in social stress and negative effects on production. Yet few studies have assessed the putative impact of positive cow-cow interactions, such as proximity to preferred herd mates and engaging in grooming, on milk production and udder health. To address this, we used cattle proximity as a proxy for affiliative interactions between cows in three dairy herds in south-west England over one week study periods. We created proximity networks of dairy cows and measured cow-cow associations according to milk yield, somatic cell count (SCC; an indicator of mastitis), parity (number of lactations in the cow’s lifetime), and lactation stage (grouped by days in milk for current lactation). We then assessed associations between social factors and production and health measures (milk yield and SCC). In all three herds, cows interacted more with cows in the same parity, suggesting early social bonding may be evident later in life and that grouping animals in terms of parity might encourage affiliative interactions. Cows did not associate according to milk yield, SCC, or lactation stage. There was no significant association between milk production or SCC and the total time spent in social contact with other cows, the mean time spent with the four closest herd mates, or the number of closest herd mates of the same parity. We suggest that further research on positive social environments for dairy cattle is warranted in the interests of improving welfare and enabling a more robust assessment of the putative effects on production and health parameters

Contribution of the diatom Navicula sp. to the growth of Penaeus vannamei post-larvae in biofloc system: a quantitative stable isotope assessment

ABSTRACT The addition of Navicula sp. to shrimp nurseries can improve the growth of Penaeus vannamei reared in biofloc systems. However, the contribution of microalgae to the biofloc formation and the effective contribution to shrimp nutrition remain unknown. In this study, Navicula sp. was added to biofloc nursery systems of P. vannamei at distinct time frequencies for evaluating its nutritional contribution to shrimp growth. Nursery rearing was carried out in bioflocs for 35 days at a stocking density of 3000 post-larvae m−3. Shrimp were fed using a commercial feed plus fresh culture of Navicula sp. at different frequencies: no addition of Navicula sp. (WN – control), the addition of 10 × 104 cells mL−1 of the diatom every 5, 10 and 15 days (N5, N10 and N15, respectively). Food sources relative contribution to P. vannamei development was estimated using a Bayesian mixture model. The isotopic discrimination factor (Δ15N and Δ13C) for each food source was determined experimentally. After 35 days of culture, survival (∼93 %) was similar across all treatments but there was a significant difference in weight gain and feed conversion ratio. The N10 treatment (0.50 ± 0.05 g, 0.99 ± 0.01) exhibited better growth parameters when compared to the WN treatment (0.33 ± 0.07 g, 11.46 ± 0.30). Biofloc was the food source most assimilated by shrimp followed by Navicula sp. and commercial feed. Contribution of Navicula sp. was higher in the N5 treatment. In the treatments with diatom addition, an inverse correlation was observed between the relative contributions of biofloc and Navicula sp., indicating that Navicula sp. is not in the biofloc composition, but it is directly consumed by P. vannamei post-larvae. Biofloc and Navicula sp. exhibited larger contributions to the growth of shrimp, reinforcing the importance of natural food sources to the aquaculture of P. vannamei post-larvae.

Application Of Microbubble Technology To Increase Oxygen Content In The Aquaculture Of Tambaqui (Colossoma Macropomum)

The oxygen consumed is used to oxidize food substances to produce energy. Therefore, the metabolic rate is usually indicated by the rate of oxygen consumption per time unit. In most intensive aquaculture systems, oxygen content is widely used due to the high stocking density and maximum feeding rates. This study aimed to evaluate the growth performance of freshwater pomfret (Colossoma macropomum) treated with increased oxygen in two different systems. The study was conducted in a laboratory scale by applying T-test data analysis. The difference of treatment level applied in the comparison of aeration and microbubble consists of two treatments and three replications. The researcher used commercial floating pellets PF0 with 25% protein content, the feeding rate was 5% of the biomass. The feed was given daily during the culture for two times a day. Data of the study were analyzed using T-test on the Statistical Product and Service Solutions (SPSS) software Version 17.0. Results of the study showed that aeration system using microbubble resulted in dissolved oxygen (DO) of 6.5 ± 0.17, 100% pomfret fish survival rate (SR), Survival Growth Rate (SGR) of 1.83 ± 0.24, Feed Conversion Ratio (FCR) of 1.37 ± 0.17, Protein Efficiency Ratio (PER) of 2.79 ± 0.37, Feed Utilization Efficiency (FUE) of 0.67 ± 0.09, Absolute Weight Growth of 52.02 ± 1.60; it was better than using aeration. This study has developed a model of freshwater pomfret fish aquaculture to provide growth value.

Integration of IoT in Small-Scale Aquaponics to Enhance Efficiency and Profitability: A Systematic Review.

Aquaponics combines aquaculture and hydroponics to offer a sustainable approach to agriculture, addressing food security issues with minimal environmental harm. However, small-scale practitioners face challenges due to a lack of professional knowledge in water chemistry and system maintenance. Economic hurdles, such as operational costs and energy-intensive components, hinder the viability of small-scale aquaponics. Selecting suitable fish and plant species, along with appropriate stocking densities, is crucial. Media Bed (MB), Deep Water Culture (DWC), and the Nutrient Film Technique (NFT) are commonly used hydroponic techniques. This study outlines optimal conditions, including water quality, temperature, pH, and nutrient concentrations, essential for symbiotic fish and plant cultivation. Integrating IoT technology enhances efficiency and profitability by optimizing resource utilization, monitoring water quality, and ensuring optimal growth conditions. Knowledge sharing among practitioners fosters innovation and sustainability through collaborative learning and best practices exchange. Establishing a community for knowledge sharing is vital for continuous improvement, advancing small-scale aquaponics towards a more efficient and sustainable future.

Effect of stocking density and feeding regimes on physiological recovery in stunted Labeo rohita fingerlings reared in cages

Aim: To find out the physiological recovery status of stunted fingerling of Labeo rohita reared in floating net cages at different stocking densities and feeding rations in cages. Methodology: Stunted fingerling (8 months) of L. rohita with an average body weight of 38.23 ± 1.90 g and length 14.65 ± 0.30 cm were stocked in cages at different densities viz. T1 (10), T2 (15), T3 (20) and T4 (25) fish m-3 and varying levels of feeding rations such as 3, 4, 5 and 6% for 330 days with crude protein (28%) pellet were fed twice a day. The 4×4 factorial design was used, and each stocking density and feeding level were triplicated. A total of 48 numbers of square shaped floating net cage, made of HDPE, each measuring 27 m-3 with 6 mm mesh size were used for the experiment. Results: A significant physiological recovery was observed in the T1 (10*5 and 10*6) treatment groups, which showed highest Hb (11.23± 0.08 g d l-1), RBC (2.83 ± 0.03 ×106 cum m-1), PCV (45.76 ± 0.16 %) and lymphocyte (69.32 ± 0.12 %) content at the end of the experiment. Similarly, significant changes were observed in glucose, cortisol, and lactate dehydrogenase, which were highest in T4 and normal in T1 group as the experiment progressed. Interpretation: The result of present study recommends that cage culture of stunted Labeo rohita is possible in Indian reservoirs with lower stocking density 10 m-2 and feeding ration of 5% body weight which maintains better physiological conditions for optimal growth of fish. Key words: Cage culture, Feeding ration, Labeo rohita, Physiological parameters, Stunted, Stocking density

Influence of different stocking densities of pearlspot (Etroplus suratensis) on plankton diversity indices of biofilm-based rearing system

Aim: Biofilm-based aquaculture systems, proven cost-effective, reduce the need for expensive supplementary feed. The biofilm acts as a natural planktonic food source for reared organisms. Previous research highlighted the influence of fish stocking density and biomass on plankton diversity in different aquaculture settings, underscoring the significance of these factors in biofilm-based systems. Hence, the present study attempted to understand how varying stocking densities of pearlspot (Etroplus suratensis) influence plankton diversity indices in the biofilm-based aquaculture system. Methodology: The present experiment was designed in 5 Practical Salinity Unit (PSU) brackishwater with soil-bottomed FRP circular (500 L) tanks for 60 days. The sugarcane bagasse was used as a substrate forbiofilm production after fertilization with cow dung, urea, and lime. Fries of pearlspot (4.67 ± 0.04 mm 1.71 ± 0.03 g-1) were stocked at four different stocking densities in triplicates viz T1 (50 nos); T2 (100 nos), T3 (150 nos) and T4 (200 nos) fish fry m-3 in the biofilm-based rearing system. Plankton samples were collected from water and biofilm deposited on the substrate and analyzed for diversity indices. The Shannon Diversity Index, Simpson Diversity Index, Simpson Dominance Index, and Margalef Richness Index were used to compute the plankton diversity indices in different treatments using standard equations. Results: In the current investigation, lower stocking densities with lower fish biomass were associated with significantly higher (P≤0.05) Shannon Diversity Index, Simpson Diversity Index, and Margalef Richness Index in water. In contrast, the Simpson Dominance Index in water showed a significantly lower (P≤0.05) value for treatments with lower fish biomass than for treatments with higher biomass. Interpretation: The values obtained for various diversity indices indicated that a biofilm-rearing system with lower E. suratensis biomass produced more planktonic abundance, evenness, and species richness. Key words: Biofilm, Pearlspot, Plankton diversity, Stocking density

The influence of different stocking density on growth rate and survival rate koi larvae (Cyprinus carpio)

Abstract Stocking density has an important role in the survival and growth of fish larvae. The purpose of this study was to determine the optimal stocking density level for larval rearing with improved feed. Tubifex sp. which has a high protein content of about 57% and fat as much as 13%. The method used was the experimental method with a completely randomized design (CRD) on 4 different treatments of stocking density with 3 replications. The treatments given were P0/Control (1 individual/L), P1 (2 individuals/L), P2 (3 individuals/L), and P3 (4 individuals/L) maintained for 49 days. The results obtained during the study were the growth rate values of P0 (0.021 gram/day), P1 (0.017 gram/day), P2 (0.016 gram/day), and P3 (0.017 gram/day). The survival rates are P0 (90.00%), P1 (91.00%), P2 (90.33%), and P3 (87.50%). Absolute length values P0 (1.94cm ), P1 (1.70cm ), P2 (1.70cm), and P3 (1.77 cm) The quality of the water obtained is that the temperature ranges from 26–29, the pH is 6.8–8.1, and the DO is 5–6. The results showed that different stocking densities had no significant effect (p > 0.05) on the survival and growth rate of koi fish.

Long-term effects of pre-weaning social housing on response to a social and housing transition in pregnant heifers

Dairy cattle are routinely managed in social groups and subject to various management and social transitions, yet conventional approaches to rearing dairy calves limit social experience during early weeks of life. The objective of this study was to evaluate long-term effects of dairy calf social housing, with calves housed individually or in pairs, on long-term behavioral responses observed in pregnant heifers following social regrouping and introduction to a novel housing environment. Holstein heifers were raised during the milk-feeding period (provided 8 L/d milk replacer) in either individual pens (n = 20 heifers) or paired pens (n = 20 pens; 1 focal heifer/pen) and subsequently identically managed in groups on pasture from 9 weeks of age. At 30 d before expected calving, pregnant heifers were moved from pasture to a free stall barn, which represented introduction to a novel social group and an unfamiliar housing environment. Behavior was continuously recorded from video for 24 h, beginning at 0000 h on the day after introduction, to characterize feeding behavior, locomotor activity, and stall usage, as well as social proximity and competitive behavior surrounding the feed bunk and stall. Stocking density of the free stall barn fluctuated and was categorized as low (≤75%, 100 × animals in pen/available stalls), medium (>75%, 100%), or high (≥100%). Body weights obtained following calving indicated that previously PH heifers were heavier (632.3 vs. 593.4 kg; PH vs. IH), and body weight was included as a covariate in analysis of feeding behavior. Upon introduction to the free stall pen, previously PH heifers spent more time walking (1.9 vs. 1.3 min/h) with no effect of calf social housing on duration of lying time. However, stall use was subject to an interaction between previous housing treatment and stocking density and differed overall between previous housing treatments; previously PH heifers spent less time in the stall, particularly at high stocking density (29.4 vs. 48 min/h), due to shorter (29.6 vs. 95.7 min/visit) but marginally more frequent stall visits. Previously pair-housed heifers were also less likely to be displaced from a stall (44 vs. 85% of heifers replaced; PH vs. IH). Feeding behavior was similarly influenced by previous housing treatment particularly at high stocking density, with previously PH heifers spending more time feeding (8.2 vs. 4.2 min/h) and visiting the feed bunk more frequently (1.5 vs. 0.8 visits/h). These results suggest that preweaning social housing had long-term effects on behavior and ability to adapt to a novel environment which became most apparent under heightened competitive pressure.

Stocking density at feeders and drinkers and temporal feed restriction affects dairy cows' drinking behavior

Water is an essential resource for dairy cows and its consumption is closely linked to feed intake. Social competition can lead to changes in drinking behavior, especially for subordinate cows. We studied how changes in stocking density at the feeder (varied between 1 or 2 cows per feeder), and drinker (varied between 6 or 12 cows per drinker) and a temporal feed restriction (14 or 24 h access) impacts drinking in 4 groups of 6 cows each, following a Latin Square design. Within each group of 6 focal cows, we recorded drinking behavior and 2 were identified as most dominant, 2 as most subordinate, and the 2 others as intermediate, based on success in agonistic interactions at the drinker. Cows drank less water when feed availability was restricted (on average 5.3 L/d less ± 3.4; 4.5% average difference). Subordinate cows also spent less time drinking when overstocked (9.3 min/d less ± 6.7; 24.3% difference). During treatments with more competition, cows were more likely to be observed drinking in the hours after the peak in drinking observed for the control treatment. A high level of competition among group-housed animals is considered a welfare problem and can lead to injuries and reduced production. Our findings provide evidence that feed restriction and higher stocking density of cows at the drinker and feeders changes the drinking behavior of cows, with subordinate animals experiencing more pronounced effects.

High species richness of sheep-grazed sand pastures is driven by disturbance-tolerant and weedy short-lived species.

We selected 15 sheep-grazed sand pastures along a gradient of increasing grazing intensity to study the fine-scale patterns of main biomass fractions (green biomass, litter) and that of plant species and functional groups (life forms and social behaviour types). We classified them into five grazing intensity levels based on stocking density, proximity to drinking and resting places and the number of faeces. We aimed to answer the following questions: (i) How does increasing intensity of sheep grazing affect the amount of green biomass, the species richness and their relationship in sand pastures? (ii) How does increasing intensity of sheep grazing affect the biomass of perennial and short-lived graminoids and forbs? (iii) How does the disturbance value-expressed in the biomass ratio of disturbance-tolerant and ruderal species-change along the gradient of grazing intensity? A unimodal relationship between green biomass and species richness was detected; however, the ordination (canonical correspondence analysis, CCA) showed no clustering of pastures subjected to the same levels of grazing intensity. Along the grazing intensity gradient we found an increasing trend in species richness and significant differences in green biomass (decreasing trend), litter (decreasing trend), graminoids (decreasing trend) and short-lived forbs (increasing trend). We found an increasing amount of disturbance-tolerant and ruderal species with increasing grazing intensity. We suggest that we might need to use multiple scales for sampling and a fine-scale assessment of grazing intensity. Our findings might be instructive for pastures in densely populated regions, which are prone to the encroachment of disturbance-tolerant and ruderal species.

Effect of Stocking Density on the Growth of the Endangered Amazonian Fish Hypancistrus zebra (Siluriformes: Loricariidae)

ABSTRACTStocking density has a significant influence on animal homeostasis, and so is a crucial factor in the management of organisms in captivity and an important role in ex situ conservation of endangered species. Hypancistrus zebra is an endemic fish species from the Xingu River, Brazil—considered Critically Endangered since the early 2000s due to fishing pressure and, more recently, due to habitat changes resulting from the construction of the Belo Monte Hydroelectric Dam. The implementation of appropriate management in captivity is of utmost importance for its conservation, particularly in enhancing ex situ breeding techniques. This study aimed to evaluate the growth of juvenile H. zebra in aquaria with three different stocking density levels. The juveniles were distributed between three treatments, each with three replicates. We found no correlation between biomass and aquarium volume. The highest correlation coefficients were found between growth rates and densities related to the number of individuals per shelter area. Mortality rate was directly related to the initial number of fish in the aquariums, with larger populations showing higher mortality rates. The treatment with lower stocking density displayed the highest growth rate, while the treatment with higher density had the lowest growth rate, with a 23.38% difference between them.

The Effect Of Stocking Densities On Growth And Survival Rate Of Thai Mahseer (Tor Tambroides) During Nursery Stage.

Abstract Tor Fish are freshwater fisheries resources that have the potential to be found in Indonesia. Tor fish has been in high demand among entrepreneurs and the broader public. Tor tambroides (Sapan fish or Thai mahseer fish seed fish), Tor douronensis (Semah or Garing fish), Tor soro (Soro, Lempon, or Dewa fish), and Tor tambra are the four kinds of Tor fish native to Indonesia. Tor fish is a native indigenous freshwater fish from Indonesia that is on the verge of extinction. The Tor tambroides fish population in nature has declined and is on the verge of extinction as a result of widespread poaching for eating and trade as an ornamental fish. Thai mahseer fish seed fish cultivation activities include hatchery, nursery and enlargement. To protect populations of Thai mahseer fish seed fish from scarcity, Thai mahseer fish seed fish cultivation needs to do to prevent the scarcity of Thai mahseer fish seed fish in their natural habitat and Thai mahseer fish seed fish have high potential as freshwater fish in the aquaculture sector. This research aims to determine the impact of various stocking densities on growth and survival rates for Thai mahseer fish seeds, as well as the optimal density to support growth and survival rates. The study used a Random Design Complete (RDC) with four treatments and five replications. Feeding was provided ad libitum in the morning and evening. Given differences in the stocking density of Thai mahseer fish seeds, the results revealed a significant impact on all treatments. Treatment 1 had the greatest daily growth rate with a stocking density of 2 seeds/L and a yield of 0.015±0.003; specific growth rate. The highest absolute weight growth obtained was in Treatment 1 with a yield of 1.01gr; the highest absolute length growth obtained was in Treatment 1 with a yield of 2.9cm; and the highest survival rate for Thai mahseer fish seeds was obtained in Treatment 1 with a yield of 80%.