High Breeding Density Research Articles

Effects of stocking densities on growth, organ index, serum biochemistry, gut morphology and microbiota of young ducks in a rice-duck-crayfish coculture system.

The rice-duck-crayfish (RDC) coculture system, an ecologically efficient breeding method, supports ducks' natural habits and enhances duck welfare. However, the optimal stocking density and its influence on duck health in this system remains undetermined. The study examined the effects of stocking densities on growth, organ index, serum biochemistry, gut morphology and microbiota of ducks in RDC system. A total of five hundred and forty 20-day-old Nonghu No. 2 ducks were randomly divided into low-density (8 birds/666.67 m2, LD), medium-density (12 birds/666.67 m2, MD) and high-density (16 birds/666.67 m2, HD) groups, with three replicates in each group, and the symbiosis period was up to 40 days until rice tasselling. There were no significant differences in final body weight, average daily gain, or feed:gain ratio between groups (p>0.05); the liver and spleen indices of ducks in HD group were significantly greater than in LD group (p<0.05); the serum albumin concentration in HD group decreased, whereas creatine kinase activity increased (p<0.05); the ileal crypt depth significantly increased; and the ileal villus height and villus/crypt ratio significantly decreased in ducks in MD and HD groups than in LD group (p<0.05). Additionally, the abundance of cecal Deferribacterota and Spirochaetota increased significantly (p<0.05), while the abundance of Firmicutes decreased significantly (p<0.05) with increasing stocking density. Moreover, the increase in stocking density significantly decreased the abundance of some beneficial bacteria (Faecalibacterium and Fournierella) and increased the abundance of some harmful bacteria (Mucispirillum and Brachyspira) (p<0.05). These preliminary results suggest that moderately high-density breeding doesn't significantly affect duck growth, but increased stocking density led to changes in cecal microbiota and dysbiosis. Reducing stocking density positively affects immune parameters and ileum morphology.However, due to the limited number of total replicates of the study, further research is needed to validate the reliability of the results.

Trends in greater sage‐grouse lek counts relative to existing wind energy development in Wyoming

AbstractRapid increases in wind energy development globally highlight the need to evaluate how electricity generation may impact wildlife. The greater sage‐grouse (Centrocercus urophasianus; hereafter, sage‐grouse) has experienced range‐wide population declines, primarily due to habitat loss and degradation. Studies have documented a negative association between oil and gas development and sage‐grouse populations. However, potential sage‐grouse population declines associated with wind energy development have not been adequately addressed. We investigated the relationship between wind energy infrastructure and changes in male sage‐grouse counted on leks from 2000–2020 in Wyoming, USA, using Bayesian state‐space models. Our study was conducted in central and southwest Wyoming in the vicinity of 10 wind energy facilities that were in proximity to sage‐grouse leks occurring outside of Wyoming's Core Areas (i.e., areas of high breeding densities of sage‐grouse designated for restricted development by the State of Wyoming) and dominated by big sagebrush (Artemisia spp.) communities. Facilities became operational between 1998 and 2010 and had an average of 67 turbines. Covariates describing wind energy infrastructure included distance to the nearest wind turbine, and the number and distribution (clustering) of turbines within 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 km. We also explored whether males attending leks exhibited lagged responses of 1–7 years following development. We used counts from 78 leks located within 15 km of the 10 wind energy facilities, consisting of 288 counts before and 845 counts after development. We expected that trends in male lek attendance would experience a delayed negative response following wind energy development like other forms of anthropogenic features. However, we failed to detect a relationship between male sage‐grouse lek attendance and proximity to, density of, or distribution of wind turbines following development in all models. Our findings were based on the average lek in our analysis being 6.5 km from a wind turbine and most turbines were clustered such that undisturbed habitat surrounding leks remained. Therefore, interpretation of our results should be restricted to siting practices of the facilities that we evaluated because direct habitat removal and fragmentation resulting from any form of energy development is unlikely to benefit sage‐grouse populations. Our study evaluated the response of low‐density, peripheral populations of sage‐grouse to wind energy development outside or near the edge of Core Areas. As such, our results should not be extrapolated to higher density sage‐grouse populations occurring in Core Areas.

The evolution of sex roles: The importance of ecology and social environment

Males and females often have different roles in reproduction, although the origin of these differences has remained controversial. Explaining the enigmatic reversed sex roles where males sacrifice their mating potential and provide full parental care is a particularly long-standing challenge in evolutionary biology. While most studies focused on ecological factors as the drivers of sex roles, recent research highlights the significance of social factors such as the adult sex ratio. To disentangle these propositions, here, we investigate the additive and interactive effects of several ecological and social factors on sex role variation using shorebirds (sandpipers, plovers, and allies) as model organisms that provide the full spectrum of sex role variation including some of the best-known examples of sex-role reversal. Our results consistently show that social factors play a prominent role in driving sex roles. Importantly, we show that reversed sex roles are associated with both male-skewed adult sex ratios and high breeding densities. Furthermore, phylogenetic path analyses provide general support for sex ratios driving sex role variations rather than being a consequence of sex roles. Together, these important results open future research directions by showing that different mating opportunities of males and females play a major role in generating the evolutionary diversity of sex roles, mating system, and parental care.

Diel spatio-temporal patterns of humpback whale singing on a high-density breeding ground.

Humpback whale song chorusing dominates the marine soundscape in Hawai'i during winter months, yet little is known about spatio-temporal habitat use patterns of singers. We analysed passive acoustic monitoring data from five sites off Maui and found that ambient noise levels associated with song chorusing decreased during daytime hours nearshore but increased offshore. To resolve whether these changes reflect a diel offshore-onshore movement or a temporal difference in singing activity, data from 71 concurrently conducted land-based theodolite surveys were analysed. Non-calf pods (n = 3082), presumably including the majority of singers, were found further offshore with increasing time of the day. Separately, we acoustically localized 217 nearshore singers using vector-sensors. During the day, distances to shore and minimum distances among singers increased, and singers switched more between being stationary and singing while travelling. Together, these findings suggest that the observed diel trends in humpback whale chorusing off Maui represent a pattern of active onshore-offshore movement of singers. We hypothesize that this may result from singers attempting to reduce intraspecific acoustic masking when densities are high nearshore and avoidance of a loud, non-humpback, biological evening chorus offshore, creating a dynamic of movement of singers aimed at increasing the efficiency of their acoustic display.

Irruptive fall migrations are linked to elevated breeding abundance but are not associated with body condition or stopover duration in Northern Saw-whet Owls

Abstract Bird species that undertake irruptive migrations are good candidates for assessing density-dependent effects on stopover ecology because the number of birds using stopover sites varies considerably from year to year. Using morphometric data from a 9-year banding program and radiotelemetry (n = 25 females), we found that increases in the annual density of Northern Saw-whet Owls (NSWO; Aegolius acadicus) encountered at a fall stopover site in Nova Scotia, Canada, were not linked to female body condition or minimum stopover duration. Rather, most NSWO spent no more than 1 or 2 full days at the stopover site following radio-tagging and during their return visits to the site. Body condition indices were highest for NSWO captured near the end of the migration monitoring season, possibly reflecting birds that had recently established wintering ranges and were elevating energy stores. We used breeding abundance indices derived from Birds Canada’s Atlantic Nocturnal Owl Survey to help test the hypothesis that irruptive fall migrations in NSWO were driven by elevated breeding productivity and dispersal of immature birds (breeding success hypothesis). Indeed, irruptive fall migrations were characterized by elevated densities of immatures, but not adults, and mean breeding abundance indices for the Maritime provinces during years with irruptive migrations were higher than those for non-irruptive years. We hypothesize that prey abundance during years with irruptive migrations was sufficient to enable high breeding densities and minimize effects of elevated fall densities of NSWO on rates of mass gain and stopover duration.

White Storks nest at high densities near landfills changing stork nesting distributions in the last four decades in Central Spain

AbstractHuman-induced environmental changes are the main drivers of the ongoing redistribution of biodiversity. The millions of tons of organic waste that is added daily to landfills can increase the carrying capacity of ecological systems with direct effects on species’ population sizes and/or distributions. Understanding the effect of landfills on bird distribution is essential to assess management decisions. Our aim was to determine the role of landfills in the distribution of the breeding population of White Storks (Ciconia ciconia) in the last 4 decades. For that purpose, we used historical and current census data of breeding pairs before and after landfill exploitation. In this study, we found that landfills have altered the distribution of the breeding population over the last 4 decades in the province of Madrid, Spain. We found that birds occupied new nesting sites near landfills independently of habitat quality as defined by prey abundance and quality according to the previous studies. Nest density was higher near landfills and increased after the landfills began to be utilized by this species. Population growth and extremely high breeding densities may translate into conflicts with humans, particularly when new nesting sites are in urban areas, and possibly alter the perception of this bird species by the human population. Landfill closures, mandated by the European Landfill legislation, are an opportunity to reduce the effects of landfills on animal populations, and reduce human–wildlife conflicts. However, there must be a process of transition and a preliminary evaluation of habitat quality and suitability in the region to avoid a dramatic decline of the White Stork population.

Determinants of departure to natal dispersal across an elevational gradient in a long-lived raptor species.

Attributes of natal habitat often affect early stages of natal dispersal. Thus, environmental gradients at mountain slopes are expected to result in gradients of dispersal behavior and to drive elevational differences in dispersal distances and settlement behavior. However, covariation of environmental factors across elevational gradients complicates the identification of mechanisms underlying the elevational patterns in dispersal behavior. Assuming a decreasing food availability with elevation,we conducted a food supplementation experiment of red kite (Milvus milvus) broods across an elevational gradient toward the upper range margin and we GPS-tagged nestlings to assess their start of dispersal. While considering timing of breeding and breeding density across elevation, this allowed disentangling effects of elevational food gradients from co-varying environmental gradients on the age at departure from the natal home range. We found an effect of food supplementation on age at departure, but no elevational gradient in the effect of food supplementation. Similarly, we found an effect of breeding density on departure age without an underlying elevational gradient. Supplementary-fed juveniles and females in high breeding densities departed at younger age than control juveniles and males in low breeding densities. We only found an elevational gradient in the timing of breeding. Late hatched juveniles, and thus individuals at high elevation, departed at earlier age compared to early hatched juveniles. We conclude that favorable natal food conditions, allow for a young departure age of juvenile red kites. We show that the elevational delay in breeding is compensated by premature departure resulting in an elevational gradient in departure age. Thus, elevational differences in dispersal behaviour likely arise due to climatic factors affecting timing of breeding. However, the results also suggest that spatial differences in food availability and breeding density affect dispersal behavior and that their large-scale gradients within the distributional range might result in differential natal dispersal patterns.

The Microorganism Concern in the Aquaponics System

Aquaponics system (AP) is a promising form for mass-produced food in the future. The system reduces the mass water demand for food production. It solves the problem of nitrogenous waste removal from the recirculating aquaculture systems (RAS) by connecting with the hydroponic system (HP) in series. Microorganisms are essential in biochemical activities in an aquaculture system, such as nitrogen cycling, waste decomposition, and detoxification. However, excessive microorganisms in the system will increase the disease risk for aquatic organisms and plants. In the RAS system, high-density breeding enriches nutrients. That microbial management is even more critical. Through the design of zone isolation, the system confines different biochemical reactions to specific intervals, enhances its performance by shaping the dominant bacterial phase with environmental advantages, and simultaneously reduces the disturbance of microorganisms to the cultured organisms. Aquaponics farming, which emphasizes the symbiotic relationship between plants, aquatic organisms, and microorganisms, would create a more diverse and complex microbiota than the RAS system. Relevant studies have shown that the uncoupled aquaponics system using microbial zone management may be the right way to reduce management risks and increase production capacity. Research on the microbial phase of aquaponic systems is still minimal; limited research shows that the microbiota in the aquaponics system may vary considerably with the seasons and the geographical location of the farm. More active bacterial research and the establishment of effective management measures are the core technologies of future aquaculture management.

Water quality indicators in high-density cage farming of trout

Trout fishing means raising fish in water whose temperature does not exceed +18°C under completely or partially artificial conditions. Today, several fish belonging to the salmon family are bred in cold water fisheries in the world. These are river trout (Rainbow trout - Oncorhynchus mykiss), brook trout (Brown trout - Salmo trutta), and brown trout (Brook trout - Salvelinus fontinalis). Currently, river trout breeding dominates global production. Its cultivation has been mastered in almost all regions [8]. In the article, the water quality indicators were studied during high-density breeding of trout in the cage method at the “Golden Fish” fishery LLC, located in the Khojakent reservoir in the Tashkent region of Uzbekistan. This includes water temperature, dissolved oxygen content, and water hydrogen potential, as well as information on fish growth, development, nutrition, and reproduction.

An analysis on the preliminary benefits of aquaculture smart aeration control

Aquaculture in Taiwan is characterised by high breeding densities of up to five times higher than the normal breeding densities. Pollution in the breeding environment and its adjacent waters have exacerbated the occurrence of disease outbreaks in fish, shrimp and shellfish, which greatly impacted the economy. Therefore, the parameters pertaining to water quality status, especially dissolved oxygen are particularly important. In addition to the rising cost of labour, land, infrastructure and other materials, the capital needed to engage in aquaculture has risen, whereas the profits have decreased. This limits the growth of aquaculture and fisheries. To overcome this problem, it is essential to shift towards efficient and ecologically precise smart aquaculture. The application of industrialised and smart systems in the vertical diffusion and in-depth integration of aquaculture facilitates decision-making, improves the level of intelligence in breeding, and enhance aquaculture's contribution to Taiwan's economy.

Aerial Drones Reveal the Dynamic Structuring of Sea Turtle Breeding Aggregations and Minimum Survey Effort Required to Capture Climatic and Sex-Specific Effects

Quantifying how animals use key habitats and resources for their survival allows managers to optimise conservation planning; however, obtaining representative sample sizes of wildlife distributions in both time and space is challenging, particularly in the marine environment. Here, we used unoccupied aircraft systems (UASs) to evaluate temporal and spatial variation in the distribution of loggerhead sea turtles (Caretta caretta) at two high-density breeding aggregations in the Mediterranean, and the effect of varying sample size and survey frequency. In May–June of 2017 to 2019, we conducted 69 surveys, assimilating 10,075 inwater turtle records at the two sites. Optimal time interval between surveys to capture the dynamics of aggregations over the breeding period was &amp;lt;2-week intervals and &amp;gt;500 turtles (from the combined surveys). This minimum threshold was attributed to the core-area use of female turtles shifting across surveys in relation to wind direction to access warmer nearshore waters and male presence. Males were more widely distributed within aggregations than females, particularly in May when mating encounters were high. Most males were recorded swimming and oriented parallel to shore, likely to enhance encounter rates with females. In contrast, most females were generally stationary (resting on the seabed or basking), likely to conserve energy for reproduction, with orientation appearing to shift in relation to male numbers at the breeding area. Thus, by identifying the main factors regulating the movement and distribution of animals, appropriate survey intervals can be selected for appropriate home range analyses. Our study demonstrates the versatility of UASs to capture the fine-scale dynamics of wildlife aggregations and associated factors, which is important for implementing effective conservation.

Bacterial polyarthritis in post-weaning pigs in a high-density swine breeding area in Italy.

We assessed the bacterial agents found in 8-12-wk-old post-weaning pigs with arthritis. The bodies of 178 post-weaning pigs from 90 farms (average of 2 pigs/farm) with recurrent problems of lameness and swollen joints in a high-density breeding area were submitted for autopsy and sampled for further bacterial investigation. The most common articular gross lesions and histopathologic findings were serofibrinous (95 of 178; 53%) or serous (65 of 178; 37%) arthritis; suppurative lesions were less frequent (18 of 178; 10%). In 133 of 178 (74.7%) cases, a bacterial agent was detected in joints. Mycoplasma hyorhinis was the most common bacterium detected (82 of 133; 61.6%). Haemophilus parasuis and Streptococcus spp. were observed in 27 of 133 (20.3%) and 24 of 133 (18.0%) cases, respectively. Other bacteria in the 113 cases, considered less important, in order of their low frequency, were Mycoplasma spp. (13; 9.8%), Trueperella pyogenes (11; 8.2%), Mycoplasma hyosynoviae (4; 3.0%), Staphylococcus spp. (3; 2.2%), Escherichia coli (2; 1.5%), and Actinobacillus spp. (2; 1.5%). Our results highlight the primary role of M. hyorhinis compared to other microorganisms involved in young pigs with arthritis.

Real-time detection and tracking of fish abnormal behavior based on improved YOLOV5 and SiamRPN++

In recirculating aquaculture system, the abnormal behavior of fish is usually caused by poor water quality, hypoxia or diseases. Delayed recognition of this behavior will lead to large number of fish deaths. Thus, real-time detection and tracking of fish that behaviors abnormally is an effective way to promote the fish welfare and to improve the survival rate as well as economic benefits of aquaculture. However, due to the high-density breeding, the targets in the fish images are often quite small and in occlusion, which causes high false detection and target loss rate. This article proposes a combined end-to-end neural network to detect and track the abnormal behavior of porphyry seabream. The detection algorithm passes the initial value of the target into the tracking algorithm, and the tracking algorithm tracks subsequent frames to achieve end-to-end abnormal fish behavior detection and achieve high-speed and accurate tracking of abnormal behavior individuals.In the target detection part, YOLOV5s is improved by incorporating multi-level features and adding feature mapping. Compared with the original network, the detection precision AP50:95 is increased by 8.8% while AP50 reaches 99.4%. In the target tracking part, this paper achieves multi-target tracking of abnormal fish based on single-target tracking algorithm SiamRPN++. The tracking precision is 76.7%. By combining the two approaches, individual fish with abnormal behavior can be detected precisely and tracked in real time.

The Long-Term Monitoring of Bird Populations on Kolguev Island in the Barents Sea

Kolguev Island (69˚05′ N 49˚15′ E) is located in the Pechora Sea, the southeastern part of the Barents Sea. The island’s ecosystem is unusual due to the total absence of rodents and specialized predators such as weasels, while non-specialized predators such as Arctic (Vulpes lagopus) and red (V. vulpes) foxes and Rough-legged Hawk (Buteo lagopus) are common. Currently, 111 bird species have been registered here, of which 58 are nesting. The absence of rodents and the relatively stable predation pressure have resulted in the high abundance of many bird species: Willow Ptarmigan (Lagopus lagopus), several goose species, some waders, and passerines. Over the 125-year history of ornithological studies on Kolguev, the island avifauna has changed significantly. The trend of an increase in the proportion of widespread and Siberian species together with a decrease in the proportion of Arctic species was observed. Since 2006, a thorough monitoring of Kolguev avifauna has been carried out, during which the dynamics of the bird population densities have been traced. The abundance of Black-bellied Plover (Pluvialis squatarola) and Dunlin (Calidris alpina) decreased, while the numbers of Barnacle Goose (Branta leucopsis) have increased sharply since the 1980s. The breeding density of Rough-legged Hawk has also increased in recent years. The long-term monitoring of Kolguev ecosystems has indicated the high international conservation value of the island due to the high breeding density of many bird species. Our study, covering more than a century of avifaunal studies with almost annual monitoring over the past three decades, provides an unusually long and detailed time-series for an Arctic island.

A detection method of the turned white belly fish based on improved SSD

Aquaculture water pollution and fish disease caused the phenomenon of fish turning white belly. The accurate detection of the phenomenon of fish turning white belly was of great significance for emergency warning, reducing loss and improving the quality of aquatic products. There were few studies on the detection of the turned white belly fish in the fish swarm. The current research was mainly to identify single the turned white belly fish under a simple background, which was not applicable in the real aquaculture environment. In order to solve the above problems, a detection method of the white belly fish based on improved SSD was proposed in a complex environment. Crucian carp was taken as the experimental object and the proposed detection method of the turned white belly fish had been tested on the real dataset. The results showed that the average detection accuracy of white-bellied fish was 99.8%, and the average detection accuracy of normal fish was 98.8%, which was suitable for the complex environment with high breeding density and many interferences.

The MallardAnas platyrhynchosin Slovenia: a review with an estimation of its current population

AbstractAlthough the Mallard is one of the most numerous and best-studied waterbirds in the world, it received almost no attention in Slovenia. It is one of the most frequently observed waterbirds in our country, with frequency often reaching 100%. Sites with lower frequency either freeze in winter or have a low number of individuals to start with. The Mallard is also the most dominant species (17.5% and 89.0%) with higher dominance at sites less suitable for waterbirds due to the lack of available shoals. Mallards reach their maximum numbers during fall migration and winter. Spring migration has no discernible peak and has been significant only for Lake Cerknica. On shallow waters, the maximum is reached in August and September, a month before fall migration begins, indicating local movement to food-rich sites. Females make up only 36.7% of the observed Mallards and reach the maximum proportion (41.5%) in winter and the lowest in April and May (14.7%), when they nest. The breeding season in Slovenia lasts from mid-January to early December, with the majority of females rearing broods from April to July. Average brood size is 6.2 ± 2.66 and declines with season, age of young and altitude. It varies between habitat types and is highest on Treatment and Coastal Wetlands (7.3) and lowest on deep waters such as Reservoirs (5.7) and Lakes (5.6). No really high breeding densities were found in Slovenia and were similar to those in other countries. Breeding densities are higher on smaller Ponds (&lt; 8 ha), on sites with isolated islands and breeding colonies of gulls and terns (e.g. Lake Ptuj). Breeding density also decreases with elevation. Slovenian breeding population is estimated at 1,473–3,763 bp and wintering population averages 22,237 (10,376–32,010) individuals. Data suggest a decline in the wintering population most likely due to warmer winters. The majority of Mallards winter in NE Slovenia, where eight of eleven sites have a maximum of more than 1,000 Mallards. Most Mallards winter on the Drava river with Ptuj and Ormož lakes, where the highest numbers of Mallards were also recorded (Lake Ptuj: 8,330 ind., Lake Ormož: 5,400 ind.). The highest number of individuals during spring migration was recorded on Lake Cerknica (4,581) and during autumn migration on Medvedce reservoir (3,379). Apart from standing waters, the highest density of wintering Mallards is found in urban sections of slow-flowing rivers, probably due to higher safety and food availability.72,731 Mallards were hunted between 2001 and 2018, mainly in NE Slovenia (28% in the Pomursko hunting management district). The number of Mallards hunted is declining in all hunting areas and has declined by 64% since 2001 and even more since the 1990s. According to hunt data, hunting is by far the most important cause of the Mallard mortality in Slovenia (97.4%), followed by predation (1.1%). The Mallard mortality in Slovenia is largely unstudied and natural mortality is most likely underestimated, not only because it does not include mortality in the pre-fledging period, a period with the lowest survival, but also because the detectability of natural mortality is considerably lower. In contrast to the hunted numbers, there have been only nine recoveries of ringed individuals from abroad in the last 100 years, suggesting that hunters may not be reporting recoveries to the ringing centre. Apart from the 1972–1975 period, when 87% of Mallards were ringed, the intensity of ringing of Mallards in Slovenia is low, resulting in only seven Mallards recovered abroad. The longest distance of a Mallard ringed in Slovenia comes from Ukraine (1,290 km), while the longest distance between ringing and recovery sites is 2,075 km from an individual ringed in Finland. The only colour morphs documented in Slovenia are Mallards with paler feathers, attributed to one of the colour aberrations resulting from lower melanin productivity. Only few hybrids and mixed pairings with other wild duck species were observed.

Grassland bird species in mountain pastures Zaprikraj and Zapleč in the southern Julian Alps, Slovenia

AbstractGrassland birds were surveyed in two mountain pastures (Zaprikraj and Zapleč) in the southern part of the Julian Alps, Slovenia. The survey was carried out during the mornings between 26 and 30 June 2005. Due to the incomplete survey (only one visit, no nocturnal or targeted surveys and late season survey), the surveyed birds’ breeding density is only a rough estimate. 167 pairs belonging to 12 species were counted, with Tree (average density of 1.64 p/10 ha) and Water Pipit (average density of 1.60 p / 10 ha) being the most abundant. Both were observed in all altitudinal belts. The highest density in individual altitudinal belt was calculated for Red-backed ShrikeLanius collurio(3.78 p/10 ha) and Water Pipit (3.61 p/10 ha). In well preserved grasslands in the study area, most species reached high breeding densities compared to other parts of Slovenia and all were recorded higher than during the 1992 survey, although still mostly within limits of the elevations elsewhere in Slovenia. Breeding density of SkylarkAlauda arvensisdecreased with the elevation. WhinchatSaxicola rubetra, Skylark and Red-backed Shrike used significantly gentler slopes, while Pipits showed no preference for particular slopes.

Causes of swine polyserositis in a high-density breeding area in Italy

We assessed the causes of polyserositis in pigs, categorized by causative agents and ages of animals affected. In a 3-y study, 246 pigs from 80 different farms with recurrent problems of polyserositis, in a high-density breeding area, were submitted for autopsy; 154 pigs with typical fibrinous serosal lesions were sampled for further bacterial and viral investigation. The most common gross lesions were pleuritis and pericarditis (141 of 154; 92%). The animals most affected were weaned pigs (139 of 154; 90%). Haemophilus parasuis and Mycoplasma hyorhinis were the most common bacteria detected and were present at the same rate (85 of 154; 55%). Other bacteria isolated were Streptococcus sp. (44 of 154; 29%), Pasteurella multocida (21 of 154; 14%), Escherichia coli (19 of 154; 12%), Actinobacillus pleuropneumoniae (7 of 154; 5%), and Trueperella pyogenes (4 of 154; 3%). Porcine reproductive and respiratory syndrome virus (PRRSV; 119 of 154; 77%) predominated among the viruses detected, followed, with lesser prevalence, by porcine circovirus 2 (40 of 154; 26%) and swine influenza A virus (19 of 154; 12%). Bacterial coinfection and coinfection of bacteria and viruses were common (128 of 154; 83%). A strong positive correlation was found between coinfection by H. parasuis and M. hyorhinis and also by H. parasuis with PRRSV.

Evaluation of novel inactivated vaccines for the SAT 1, SAT 2 and SAT 3 serotypes of foot-and-mouth disease in pigs

BackgroundThe foot-and-mouth disease (FMD) virus is classified into seven serotypes, of which the South African types have South African Territories (SAT)1, SAT2, and SAT3 that are prevalent in Africa. Especially SAT2 have spread to Arabian Peninsula and the Palestinian Autonomous Territories. Of these viruses, the incidence of SAT2 is the highest. It is important to prepare for the spread of the virus to other continents, even though most FMD viruses are bovine-derived. In particular, due to the high breeding density of pigs in Asia, more attention is usually paid to the immunity and protection of pigs than cattle. For this reason, this study investigated the immunity and protection of pigs against the SAT viruses.MethodsSpecific vaccines were developed for SAT1, SAT2, and SAT3 serotypes. These vaccine viruses were designed to be distinguished from the wild-type strain. An immunogenicity test was conducted using these vaccines in both cattle (n = 5/group) and pigs (n = 20/group).ResultsHigh virus-neutralizing titer of antibodies (> 1:100) was induced in only 2 weeks after the immunization of cattle with the individual vaccine for SAT1, SAT2 or SAT3, and a clear immune response was induced after the second immunization in pigs. When the vaccinated pigs (n = 4–5/group) were challenged by the homologous wild-type virus strain 4 weeks after immunization, all the pigs were protected from the challenge.ConclusionsThis study confirmed that these vaccines can be used against SAT1, SAT2, and SAT3 viruses in cattle and pigs. The vaccine strains developed in this study are expected to be used as vaccines that can protect against FMD in the event of a future FMD outbreak in pigs in consideration of the situation in Asia.

Hematological and immune genes responses in yellow catfish (Pelteobagrus fulvidraco) with septicemia induced by Edwardsiella ictaluri

Yellow catfish (Pelteobagrus fulvidraco) has been an economically important freshwater species in China because of its good meat quality. In present, the high-density breeding industry has suffered great damage from bacterial infections, in especial, the rapid illness and death of fish caused by bacterial septicemia leads to huge economic losses. Therefore, it is urgent and important to identify pathogenic bacteria and study its pathogenicity. In this study, we isolated a bacterial strain from the yellow catfish with typical septicemia and named it E. 719, then, by morphological observations, regression infection, biochemical identification, 16S rDNA sequence analysis and triple PCR identification, E. 719 was determined to be Edwardsiella ictaluri. Further, we infected yellow catfish with E. ictaluri to study its effects on mortality rate, hematological, histopathological disturbances and expression of immune genes. The mortality results showed that E. ictaluri was highly pathogenic, all infected fish died after 14 days post injection, and the distribution of bacteria in body kidney, spleen, liver, head kidney and brain of fish was continuously detected by measuring the amount of bacteria in the tissues. In addition, the number of red blood cells decreased significantly with the time of infection, while the number of white blood cells and thrombocytes increased. In particular, the number of monocytes and neutrophils increased significantly in the differential leucocyte count (DLC). Histopathologic changes observed by HE staining showed similar results, gill, intestine, spleen and head kidney showed obvious inflammation, bleeding and necrosis. Besides, checking by real time quantitative RT-PCR assays, in both spleen and head kidney tissues which were the major immune organs, mRNA expressions of immune gene IL-1β, TNF-α, and MR significantly increased in the early and middle stages of infection, which suggested that the infection of E. ictaluri caused a strong immune response in yellow catfish. This study provides a preliminary basis for the diagnosis and treatment of pathophysiology septicemia in yellow catfish induced by E. ictaluri.