Original title: The impact of application of Ruikexin on the health problems of weaned piglets with different PRRSV infection status
Pig breeding and respiratory syndrome (PRRS) is still one of the most economically significant viral diseases affecting pig farms in my country. In order to restore production capacity to the post-African swine fever era, many large-scale pig farms quickly put a large number of young reserve sows that have not been domesticated with strict blue ear disease into the production group, making PRRSV popular in the pig herd in an unstable state, and PRRSV spread to piglets through production sows. According to Rao Jihong et al. (2019) reports that PRRSV antigen was detected in serum of weaned piglets from 15 pig farms in 38 large-scale pig farms in China, indicating that PRRSV showed persistent infection of [1] in weaned piglets in pig farms in my country. Weaned piglets often show clinical symptoms such as eyelid edema, tear spots, shortness of breath, wheezing, body temperature rise, slow growth, lymph node swollen and increased mortality after infection with PRRSV. According to the feedback from the breeder who visited the outbound pig farm, these weaned piglets usually look healthy, but they appear clinical symptoms of blue ear disease 2 to 4 weeks after weaning. At the same time, the mortality rate increases, the average daily weight gain, the increase in treatment costs per pig, and the reduction in feed conversion rate due to infection with multiple pathogens (viruses and bacteria). Based on PRRS, a viral disease, there is currently no specific treatment method. However, it has been reported that if relevant auxiliary prevention and control measures can reduce the loss caused by PRRSV, according to M McCaw (2001) that the management measures carried out to extend antibiotic use time and reduce contact with bacteria to reduce losses during the entire acute outbreak can reduce the mortality rate of weaned piglets in a state of PRRSV viremia [2]. To this end, this study uses Ruikexin's unique triple effects of antibacterial, anti-inflammatory and immune regulation to explore the impact of Ruikexin on the health performance of weaned piglets in different PRRSV infection states, aiming to provide data support for effective prevention and control of PRRSV and promote the healthy development of the pig farming industry.
01 Production overview and health status of the target pig farm
A large-scale breeding farm in Guangxi has a basic sow inventory of 2,000, self-raised boars, and self-sufficiency of semen. This production model in the farm is a two-point production of self-bred and self-raising, mainly selling about 7-15kg of piglets. The sow herds are exempt from the vaccination of swine fever and pseudo-rabies live vaccines four times a year, and the breeding pigs and piglets are not immune to live attenuated vaccines or inactivated vaccines for blue ear disease.
First of all, starting from early January 2021, sows experienced uninterrupted miscarriage in the late stage of pregnancy, with a miscarriage rate of 6%-12%. It was not stable until mid-February. Secondly, customers who purchased the weaned piglets in February reported that they had died two weeks after entering the site, with depression, obvious eye boredom, severe joints swollen, and pale hair. At the same time, the remaining weaned piglets increased their death rate of conservation pigs three weeks after weaning and reincarnation, and their clinical manifestations were cough and asthma, clusters, shortness of breath, arthritis, and gradual weight loss. If not treated in time, the death rate will be as high as more than 15%. The tissue disease materials of 6-week-old sick pigs were collected and maintained in April were diagnosed by Zoten Laboratory. Based on the sequence comparison analysis results and the evolutionary tree constructed, preliminary judgments can be made. There may be HP-PRRSV-like strains in the samples sequenced at this site.
02 Exported weaned piglets
According to the requirements of the surrogate customer, each batch of piglets must be randomly drawn to blood test for antigens such as PRRSV, ASFV, PCV2, etc. The test results are shown in Table 1. At the same time, both African swine fever virus and circovirus type 2 antigens are negative. In order to ensure the survival rate of weaned piglets in the first month, the farm provides relevant health care based on the test results. For details of the specific health care plan, see Table 1. The concurrent farm will thoroughly clean, disinfect and dry the pens before entering the seedlings to prevent the pathogens present in the pig house from being transmitted to newly weaned piglets. The temperature in the house should be adjusted to provide a warm, dry, clean and comfortable living environment for piglets. Do a good job of ventilation to ensure fresh air in the house.
The author tracked three batches of weaned piglets, and each batch was divided into two groups for follow-up observation, and evaluated the death rate of each batch one month after entering the site. Combined with relevant testing indicators and health care plans, the health care plan for purchasing piglets in this farm is optimized, see Table 1.
Table 1 Pig herd background and corresponding treatment methods before the implementation of different health care plans in weaning group
03 Tracking results and analysis
1 month after the author followed three batches of weaned piglets and found that the first batch of weaned piglets began to have a small number of diseases the next day. The piglets had a fever, were depressed, and had a loss of appetite, and gradually increased in the future. As the course of the disease prolongs, the onset of piglets cough and asthma, breathe rapidly, and some joints are swollen. The smaller the weight, the earlier, faster, and more serious the disease. Death Tao began to appear a week after entering the market. Since each batch of PRRSV infection status is different, the death rate of one month after entering the market has different degrees of performance. The dead rate of each batch was tested by Chi-square statistics, see Table 2, Figure 1, Figure 2, Figure 3, and Figure 4 for details.
Table 2 The death rate of the weaning transgenic group within one month after the implementation of different health plans
P1 The death rate of the Ruikexin health care group was significantly lower than that of the domestic long-acting cephalosporin + feed mixed medicine health care group, with extremely significant differences (P＜0.01). As shown in Figure 1.
Figure 1 The death rate of different health care plans in the weaning transgenic group of P1 group within one month was marked with different letters (a, b). The χ2 test was statistically different between groups (P 0.01).
, and the P2 Ruikexin Healthcare Group's death rate was significantly lower than that of the domestic long-acting cephalosporin + feed mixed medicine healthcare group, with a very significant difference (P＜0.01). As shown in Figure 2.
Figure 2 The death rate of different health care plans in the weaning group P2 group within one month was marked with different letters (a, b). The χ2 test was statistically different between groups (P 0.01).
At the same time in PRRSV antigen-negative weaned piglets, the P3 Ruikexin Health Group's death rate was significantly lower than that of the domestic long-acting cephalosporin + feed mixed medicine health care group, with a very significant difference (P＜0.01). As shown in Figure 3.
Figure 3 The death rate of different health care plans in the P3 group within one month after the implementation of different health care plans were marked with different letters (a, b). There were statistical differences between groups by χ2 test (P 0.01).
Overall, it can be seen that the death rate of weaned piglets with PRRSV antigen negative one month after entering the site was lower than that of weaned piglets with antigen positive one (P <>
Figure 4 The average mortality rate within one month after the implementation of different health care plans for different batches of weaning groups was marked with different letters (a, b, c). There were statistical differences between groups by χ2 test (P 0.01).
Overall, it can be seen that the death rate of the three batches of Ruikexin Health Care Group was significantly lower than that of the domestic long-acting cephalosporin and feed mixed medicine health care group, with a very significant difference (P <>
04 Analysis and discussion
4.1 The impact of the infection status of blue ear disease on the later mortality rate of weaned piglets
Post-weaning mortality rate is one of the main reasons for the economic loss of my country's pig farming industry. According to Julio Alvarez et al. (2015), the status of pig breeding and respiratory syndrome viruses during weaning has a significant impact on respiratory problems and mortality after weaning. When PRRSV is detected during weaning on sow farms, the mortality rate of piglets after weaning will increase during the care period. The death rate of piglets in positive batches will be 34% higher than the expected target of the pig farm, while the death rate of piglets in negative batches will be 1.8% [3]. This is consistent with the tracking results of this study. Through this study, it was also found that the mortality rate of piglets with low CT value during weaning is higher than that of piglets with high CT value, indicating that the clinical manifestations of weaned piglets with high viremia are more serious. reported from the on-site breeder that piglets with low CT values are prone to cough and asthma, joint swollen, thick and messy hairs.Therefore, the infection status of blue ear disease during weaning has a significant impact on the later death rate.
In addition to infectious factors, according to Jordan T Gebhardt et al. (2020) reports that other factors such as genetic and management-related factors may also be determinants of piglets' post-weaning mortality rate and promote the influence of infectious factors. Such as cold weather, poor ventilation in the pen, and mixed infection with other pathogens, it will also promote the increase in the death rate of weaned piglets [4][5].
Therefore, establishing an evaluation-tracking system in is an important strategy that we can currently do and can effectively improve the prevention and control of blue ear disease. We can use PCR detection to evaluate the viral infection profile and judge the viral load of the sample by Ct value. At the same time, the delivery room treatment liquid can also be collected (that is, collect testicular samples from the testicles processed after birth and castration after newborn piglets are collected, and serum is extracted for QPCR testing) is a sampling method we use in large quantities. It is simple and cheap, allowing farmers to monitor the activity of PRRSV infection in the pig herd every week, and predict the infection profile of weaned piglets before weaning, and strive for prevention and control opportunities for PRRSV prevention and control.
4.2 Ruikexin can improve the health performance of weaned piglets with different blue ear infection status
According to domestic and foreign studies, the infection of PRRSV destroys the phagocytic and bactericidal functions of macrophages, which in turn promotes the clinical manifestations of other diseases. Potential PRRSV viremia in weaned piglets can infect multiple pathogens (viral and bacterial properties) and increase the rate of death. severe pig farms can cause a 20-30% death rate. Strategic application of antibiotics is the fastest measure. Since the viremia of PRRSV lasts for a relatively long time in piglets, some drugs are quickly eliminated by people due to their short efficacy, low blood-pulmonary drug concentration, and uneven blood-drug levels caused by oral administration. According to Y Panuwat et al. (2012) reported that there were bacterial infections such as polyoxic Pasteurium, Streptococcus suis, Haemophilus parasoporum, and single-injection intramuscular injection of Ruikexin significantly reduced the death rate of conserved pigs (P <>[6]. In controlling the anti-infection of PRRSV, Ruikexin not only showed strong antibacterial ability, but also found that Ruikexin® has anti-inflammatory effects on blue ear virus. R.Moges et al. (2019) In an experiment of blue ear virus (PRRSV) in vitro infection of macrophages, it was found that PRRSV significantly promoted IL-8 secretion (6-fold increase), inhibited the production of the anti-inflammatory factor IL-10, and produced a large amount of mitochondrial reactive oxygen species (ROS). However, macrophages infected with PRRSV were treated with Ruikexin® (0.5 mg/mL), and it was found that the production of the pro-inflammatory chemokine IL-8 was significantly inhibited (P0.05), the effect of PRRSV inhibiting IL-10 production was eliminated, and the production of mitochondrial reactive oxygen species (ROS) was greatly reduced. It can be seen from this that Ruikexin® can interrupt the cascade of inflammation by inhibiting the production of proinflammatory factors, thereby effectively controlling the development of inflammation. This study also found that Recoxin® can inhibit PRRSV-induced macrophage morphological changes (elongated phenotype of cytoplasmic pseudofocal), restoring the non-regulatory phagocytosis of PRRSV-infected macrophages. This improves the bactericidal function of macrophages. This effect cooperates with the bactericidal effect of Recoxin® to prevent secondary infection of bacterial infection [7] after PRRSV infection. Therefore, the triple effects of RICKIN®'s unique antibacterial, anti-inflammatory and immune-regulating effects among many antibiotics make RICKIN® the first choice for the treatment of related diseases caused by PRRSV. The main is used in the key stages of pig farming to prevent and treat bacterial respiratory infections in individuals or groups of pigs, mainly including key stages such as delivery room, weaning, conservation, entry-level isolation period, and early mixed group stage. The purpose is to use medicine before the pigs have no clinical symptoms, which can greatly reduce the death rate of piglets and improve the growth performance of piglets . This is also the current pig farming production system has always adopted a preventive medication model to improve the survival rate of piglets.This clinical study has confirmed that Ruikexin significantly improved the health performance of weaned piglets with PRRSV antigen positive.
In short, the health of weaned piglets is the result of the complex interactions between pathogens, environment and management. Flexible application of Ruikexin can not only control and prevent weaned piglets from local epidemic major bacterial infections, but also alleviate the clinical symptoms of blue ear disease and pathogenic bacteria infection. Since this study is limited to the stage of weaned piglets, it is far from enough to successfully control the prevalence of PRRSV in the entire pig herd. At the same time, it is difficult to purify blue ear disease in the complex pig farming environment in my country at this stage. Therefore, blue ear disease prevention and control can be achieved through three key areas, namely, through the vaccination of live attenuated vaccines, to reduce the detoxification of breeding pigs, to obtain antigen-negative piglets, to strengthen biosecurity to prevent external viruses and bacteria from entering the pig farm, and to pay attention to daily management to minimize the spread of viruses on the farm.
References:
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[3] Julio Alvarez, Javier Sarradell, Barry Kerkaert, et al.Association of the presence of influenza A virus and porcine reproductive and respiratory syndrome virus in sow farmers with post-weaning mortality. Preventive Veterinary Medicine,Volume 121, Issues 3–4,2015,Pages 240-245.
[4] Jordan T Gebhardt, Mike D Tokach, Steve S Dritz, et al. Postweaning mortality in commercial swine production II: review of infectious contributing factor
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[5] Jordan T Gebhardt, Mike D Tokach, Steve S Dritz, et al. Postweaning mortality in commercial swine production. I: review of non-infectious contributing factors, Translational Animal Science, Volume 4, Issue 2, April 2020, Pages 462–484,
[6] Y Panuwat.Y Terdsuk. P Parp. et al., effect used of tulathromycin between outbreaks of HP-PRRS into the farm of Northeast Thailand. Proceedings of the 22nd IPVS Congress.2012.
[7] Desmonts de Lamache D, Moges R, Siddiq A, Allain T, Feener TD, Muench GP, et al. (2019) Immuno-modulating properties of Tulathromycin in porcine monocyte-derived macrophages infected with porcine reproductive and respiratory syndrome virus. PLoS ONE 14(8): e0221560.
Article source: Zoten Pig Industry
