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Protecting the Turkey Industry: Diseases to Watch

HPAI, aMPV, and Turkey REO virus crucial to understand and manage


15 September 2024


4 minute read

The U.S. turkey industry plays a significant role in the nation’s agricultural economy, with over 216 million turkeys produced annually, contributing to an economic impact of $103.4 billion (National Turkey Federation, 2019). Leading production states include Minnesota, North Carolina, and Arkansas, collectively yielding 5.55 billion pounds of turkey meat in 2023. Turkey meat production in 2021 was recorded at 5.558 billion pounds, underscoring its importance as a dietary staple (USDA ERS, 2024). With key export markets in Mexico and Canada, the industry remains a crucial component of U.S. agriculture. To maintain industry health, it is essential to understand diseases such as Highly Pathogenic Avian Influenza (HPAI), Avian Metapneumovirus (aMPV), and Turkey REO virus.

Highly Pathogenic Avian Influenza (HPAI) in Turkeys

HPAI, caused by influenza Type A viruses, leads to high mortality rates and substantial economic losses. Infected turkeys show symptoms such as sudden death, lethargy, lack of appetite, decreased egg production, swelling of the head, neck, and eyes, coughing, sneezing, and nasal discharge (Mumu et al., 2020; Swayne et al., 2000). The disease progresses rapidly, often resulting in significant flock mortality.

Since the outbreak began on February 8, 2022, approximately 90.89 million birds have been affected by HPAI across the United States, with 1,139 flocks (486 commercial and 653 backyard) spanning 48 states (USDA APHIS, 2024b). By the end of 2023, turkeys represented over 70% of the affected birds, causing significant financial strain due to the depopulation of millions of birds (Patyk et al., 2023). In 2024, the virus continues to spread, particularly in Minnesota, North Carolina, and Indiana, with severe economic repercussions impacting turkey product availability and livelihoods within the industry (USDA APHIS, 2024b).

Transmission of HPAI occurs through direct contact with infected birds or contaminated environments, with risk factors including poor biosecurity and wild birds near poultry farms. Depopulation remains the primary outbreak management method, while stringent biosecurity measures are crucial for protecting flocks from infection (Patyk et al., 2023).

Avian Metapneumovirus

Avian Metapneumovirus (aMPV) causes respiratory illness and reproductive issues in turkeys. Identified in the 1970s, aMPV has four known serotypes: A, B, C, and D (MacLachlan et al., 2017). Infected birds show respiratory distress, nasal discharge, swollen sinuses, and decreased egg production (Amine et al., 2023; Pringle, 1998), with high mortality rates and significant economic losses associated with outbreaks (Rautenschlein, 2020).

Diagnosis involves serology and PCR tests. There is no specific treatment for aMPV, making prevention and control paramount. Strategies include biosecurity, vaccination, and managing secondary bacterial infections with antibiotics (Nicholds et al., 2020). Both live and inactivated vaccines are used in areas where aMPV is common. Recent outbreaks have been reported in Virginia, North Carolina, and California, with increased serologic positives noted since early fall 2023. The National Veterinary Services Laboratories (NVSL) confirmed Avian Metapneumovirus subtype B in turkeys and broilers from Virginia, North Carolina, and subtype A in turkeys from California. The increase in serologic positives since late 2023 has been linked to high mortality events. Ongoing surveillance, improved diagnostics, and effective biosecurity practices are essential to mitigate the disease’s impact (USDA APHIS, 2024a).

Turkey REO Virus

The REO virus is a significant concern due to its widespread impact and limited treatment options. This virus primarily affects the leg joints of turkeys, causing lameness (Sharafeldin et al., 2016), swelling, and increased joint fluid. Symptoms include difficulty walking, lethargy, and swollen hocks, leading to welfare issues and economic losses due to increased culling, mortality, and reduced growth rates (Porter, 2018).

A survey by the National Turkey Federation (NTF) indicated that the REO virus consistently ranks among the top concerns for turkey producers. In 2019, approximately 2% of turkeys and 5% of toms were affected, resulting in higher production costs due to increased mortality and reduced feed efficiency (Graber, 2024). Transmission occurs vertically and horizontally, with oral exposure allowing the virus to infect intestinal epithelial cells and potentially spread to the heart, liver, intestines, and tendons (Nicholds et al., 2020).

Currently, turkeys have no specific treatment for the REO virus (Kumar et al., 2022). Management focuses on prevention and control through biosecurity measures, improved flock management, and ongoing vaccination research. The NTF Foundation actively funds research to develop better diagnostic tools and vaccines to reduce REO virus prevalence and impact (Graber, 2024).

Conclusion

The U.S. turkey industry’s fight against HPAI, aMPV, and REO virus underscores the need for stringent biosecurity, advanced research, and innovative technologies. Comprehensive biosecurity protocols are crucial for preventing outbreaks, while investment in vaccines and diagnostic tools enhances disease management. These efforts are vital for safeguarding flock health, maintaining productivity, and ensuring the industry’s economic viability. Continuous advancements in prevention and control will sustain and strengthen turkey production against emerging health challenges.





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Weekly global protein digest: Chinese meat exports decline, 1st US H5N1 case with no known animal exposure

Livestock analyst Jim Wyckoff reports on global protein news


13 September 2024


12 minute read

Weekly USDA US beef, pork export sales

Beef: Net US sales of 11,400 MT for 2024 were down 31 percent from the previous week and 41 percent from the prior 4-week average. Increases were primarily for South Korea (3,200 MT, including decreases of 300 MT), Mexico (1,900 MT, including decreases of 100 MT), Japan (1,500 MT, including decreases of 200 MT), Canada (1,100 MT), and Taiwan (1,000 MT, including decreases of 100 MT). Exports of 11,800 MT were down 21 percent from the previous week and 16 percent from the prior 4-week average. The destinations were primarily to South Korea (3,100 MT), Japan (2,600 MT), China (1,800 MT), Mexico (1,200 MT), and Taiwan (600 MT).

Pork: Net US sales of 29,700 MT for 2024 were up 43 percent from the previous week and 15 percent from the prior 4-week average. Increases were primarily for Mexico (14,200 MT, including decreases of 200 MT), Japan (4,300 MT), Colombia (2,400 MT, including decreases of 100 MT), China (2,000 MT, including decreases of 200 MT), and Canada (1,400 MT, including decreases of 700 MT). Total net sales of 100 MT for 2025 were for the Dominican Republic. Exports of 25,700 MT were down 8 percent from the previous week and 10 percent from the prior 4-week average. The destinations were primarily to Mexico (10,700 MT), Japan (3,800 MT), China (3,200 MT), Colombia (1,700 MT), and South Korea (1,600 MT).

Chinese meat imports have declined significantly compared to previous years

Through the first eight months of 2024, China imported 4.40 million metric tons (MMT) of meat products, down 13.9% from the same period in 2023. In August 2024, China imported 565,000 MT of meat, which was 9.9% lower than August 2023. Beef imports have been particularly affected, with volumes down 27% year-over-year in July 2024.

Several factors are contributing to lower Chinese meat imports in 2024:

  • Economic headwinds are impacting consumption of both pork and beef.
  • China has ample domestic meat supplies after building up stocks in 2023.
  • Pork production in China remains high, reducing import needs.
  • Chinese consumers are seeking cheaper protein options due to economic slowdown.

Import bans on some U.S. meat facilities have restricted supply.

Pork

  • Pork imports may grow marginally to offset a forecasted 3% decline in domestic production.
  • China’s pork output fell 0.4% year-over-year in Q1 2024, the first quarterly decline in nearly 4 years.

Beef

  • Beef imports are expected to decline in 2024 due to high year-end inventory and flat demand.
  • China’s share of global beef imports is forecast to be 5% below 2023 levels.

Poultry

  • Poultry meat imports accounted for $282 million in July 2024, resulting in a negative trade balance.

Impact on global trade

  • The U.S. has seen a fall in meat exports as China scales back imports.
  • Brazil has increased beef exports to China, up 10.2% in the first half of 2024.
  • Australia has shifted more beef exports to the U.S. and Japan as Chinese demand weakens.

Bottom line: While there have been some month-to-month fluctuations, overall Chinese meat imports remain well below 2023 levels as domestic production remains high and economic factors dampen demand. This has led to shifts in global meat trade flows, with exporters like the U.S., Brazil and Australia adjusting to changing Chinese import patterns.

Highlights of US pork group virtual briefing on key challenges

Bottom line issues for National Pork Producers Council:

Brian Humphreys, CEO of the National Pork Producers Council, said: We’re here to find solutions, not just discuss challenges. We need a 2024 Farm Bill — not an extension. We need a legislative fix to California’s Prop 12, resolutions to the labor shortage, and an active trade agenda. NPPC says moving a new farm bill this year with language restricting state animal welfare rules is the group’s top priority.

  • Need for new farm bill: “With all the stress on farmers now, it’s important that we get this moved now while we’ve got the opportunity,” Duane Stateler, president-elect of NPPC, said in the virtual briefing. “If the farm bill goes into next year, it starts all over. We have many good things in this farm bill which makes it imperative we get it done in 2024,” Lori Stevermer, NPPC president, said in the briefing.
  • Proposition 12: “The 2024 Farm Bill is a golden opportunity to address a top issue for pork producers across the country – California Prop 12,” Stevermer said. Proposition 12, a 2018 California ballot initiative, prohibits the sale of uncooked whole pork meat not produced according to the state’s arbitrary housing dimensions. The initiative places the cost and compliance burden on pork producers, who are nearly all located outside of California, and puts the industry at risk of significant consolidation, NPPC argues. The Supreme Court of the United States said this is an issue for Congress to solve, and NPPC has been urging passage of the farm bill which includes a federal solution to Prop 12. “We cannot continue down a path of unscientific rules and regulations,” Humphreys said on the call. “It’s not a question about what has happened, but it’s a question of how do we move forward and protect the U.S. from this patchwork of regulations? We appreciate the bipartisan solution in the farm bill to make that happen.” Stevermer said Prop 12 impacts extend beyond producers as it has also resulted in higher prices for consumers. “Pork prices are up on average 20% since Prop 12 went into place, and the supply is down about 20% so that’s not good for consumers, and it’s not good for farmers either,” she said.
  • Labor issues remain a concern, with the group presses for improvements to the TN skilled guestworker visa program. NPPC said policy concerns include addressing the persistent ag labor shortage and contending with inflationary impacts on production costs. While ag labor discussions often focus on the H-2A ag guestworker program for low-skilled farm laborers, pork industry officials said they also face difficulty using the TN visa program, which allows businesses to procure skilled workers from Mexico and Canada. The State Department recently made changes to the program aimed at streamlining it, but NPPC officials said they have effectively closed off the ability to use TN visas by the pork sector. “It just seems like every day there’s less and less TNs approved,” said NPPC Vice President Rob Brenneman. He explained that the program has become more important in helping producers secure the workers skilled in utilizing new production technologies that are difficult to find in the domestic labor market. “I think it’s absolutely absurd that we just keep getting TNs denied … we’ve been to the State Department, and we’ve been to the White House and had conversations, and it just seems like they’re doing everything in their power to do the opposite of what we’re asking because nothing’s changed,” Brenneman said.
  • Cost of production. NPPC officials said that besides labor shortages, producers also continue to grapple with higher production costs, though the growth in costs has slowed in areas like feed. Other fixed costs like transport, labor and utility bills mean overall production costs remain roughly 25% higher than they were three years ago, officials stressed. “While we’re getting a little relief on the feed side, we’re still seeing elevated costs of production,” said NPPC board member Scott Hays.
  • CAFOs: Officials were asked to weigh in on a lawsuit from environmental groups seeking to compel EPA to act on their petition seeking an overhaul of how the agency regulates concentrated animal feeding operations (CAFOs). NPPC and other livestock and poultry interests are backing EPA’s decision to deny the petition, as the question heads to federal court later this week. Calling the CAFO lawsuit “an attack on ag by activist groups,” NPPC’s Statler said, noting EPA was right to deny the petition. “What they’ve asked EPA to do was illegal.” Stateler praised EPA for engaging with stakeholders including NPPC on the issue to gather information before considering any additional action. “They decided to take a look and look at the facts, and they turned it over to explore the issues that are really involving all CAFOs and the ag groups, including NPPC, are participating in that process,” he added, saying the group looks forward to finding a solution that works for all involved.
  • Trade policy: NPPC continues to urge new trade agreements, but acknowledges new FTAs are unlikely. “We know that’s not how things are being done — in the manner that maybe they were, you know, 10 or 15 years ago,” Stevermer said regarding new FTAs, but she added that such agreements are not an end all be all for trade. Trade programs like the Generalized System of Preferences (GSP) and African Growth and Opportunity Act (AGOA), both pending renewal, are also important for the sector, she said.

US confirms first H5N1 case with no known animal exposure

A Missouri resident has been confirmed as the first case of the H5N1 virus with no known exposure to sick animals, according to the CDC. The individual, who was hospitalized and has since recovered, had no work-related contact with animals. The infection was identified through routine flu surveillance, rather than the targeted H5N1 program typically used for farm workers. This marks a shift in how the virus is being monitored and may indicate new patterns of transmission.

FAO food price index slips again in August

The UN Food and Agriculture Organization global food price index slipped 0.5% in August, the second straight small monthly decline, as decreases in sugar, meat and cereal grains outweighed increases for vegoils and dairy products. The August index was down 1.1% from last year. Compared to year-ago, prices declined 12.0% for cereal grains and 23.1% for sugar, while they rose 3.6% for meats, 14.3% for dairy and 8.1% for vegoils.

Weekly USDA dairy report

CME GROUP CASH MARKETS (9/06) BUTTER: Grade AA closed at $3.1750. The weekly average for Grade AA is $3.1594 (-0.0226). CHEESE: Barrels closed at $2.2750 and 40# blocks at $2.2700. The weekly average for barrels is $2.2588 (+0.0473) and blocks $2.2363 (+0.1083). NONFAT DRY MILK: Grade A closed at $1.3650. The weekly average for Grade A is $1.3550 (+0.0435). DRY WHEY: Extra grade dry whey closed at $0.5875. The weekly average for dry whey is $0.5725 (+0.0120).

BUTTER HIGHLIGHTS: In the West, butter demand varies from steady to stronger for the retail and food service sectors. In the Central region, butter demand is stronger for both as well with seasonal strength gathering. For the East, retail demand is stronger, and food service demand is steady. Cream supplies are looser with the holiday weekend contributing to market availability of loads. However, not enough to make cream volumes abundantly available throughout the country. Stakeholders convey cream availability remains relatively tight in the East. Butter production paces mostly vary from steady to stronger. Bulk butter overages range from minus 7 to 10 cents above market, across all regions.

CHEESE HIGHLIGHTS: Contacts relay cheese production schedules vary from steady to lighter throughout the U.S. In the East, milk availability for Class III processors is tempered by strong Class I bottling demand. Labor Day weekend freed up some spot milk temporarily, but contacts continue to share seasonally steady to lighter cheese manufacturing activity. In the Central region, contacts report spot milk prices ranging from $1/cwt to $2.50/cwt over Class III. That said, some cheesemakers relay getting no spot milk offers, and cheese production remains seasonally lighter. Some processors share they are shifting production focus away from blocks and back into barrels. Contacts in the West are running steady cheese production schedules despite tight spot milk availability. Some manufacturers share there are limited cheese inventories available for interested spot purchasers.

FLUID MILK: The unceasing milk production carried on across the country despite the holiday weekend. Farm level milk production proceeds to weaken over much of the East and Midwest. Processors there are feeling the pinch in production. Reported spot milk prices in the Midwest ranged from $1-over to $2.50 over Class III. Cooler temperatures are being seen over some parts of both regions, and farmers are anticipating the effects in the coming weeks. Arizona and the Pacific Northwest are also experiencing a dip in milk levels. Most of the mountain states have generally steady production. Increased levels of milk are being seen in California and New Mexico. Nationwide, school schedules have pushed Class I demand for bottling to its peak. Class II and III production is mixed as Class I draws on available milk supplies. Demands for cream and condensed skim are steady to strong. Spot loads of condensed skim are a rarity in most of the country. Cream supplies remain tight, but a small gain in cream availability was seen over the holiday weekend. It is not expected to last long, but Class IV manufacturers are making the most of it. Cream multiples range from 1.15 – 1.50 in the East, 1.16 – 1.34 in the Midwest, and 1.10 – 1.30 in the West.

DRY PRODUCTS: Low/medium heat nonfat dry milk (NDM) prices moved up at every facet in all regions this week. Clearly, markets have found some bullish tailwinds with stronger demand and tightening supplies. Dry buttermilk prices were steady in the Central/East regions, while moving higher in the West. Dry buttermilk Q4 demand has begun to stir potential market bulls. Central and West whey prices were steady to higher, while East whey prices held steady. Whey supplies are noted as very tight according to a number of processors. Lactose prices were steady to slightly lower, as international demand has been less consistent recently. Whey protein concentrate (WPC) 34% prices edged higher at every point this week on renewed interest from end users, particularly those who can alternate between WPC 34% and NDM. Dry whole milk prices were higher this week, as interest remains steady, but inventories are, and have been, noticeably tight. Rennet and acid casein prices were steady on quiet trading activity.

ORGANIC DAIRY MARKET NEWS: The first publication of the Pennsylvania Monthly Organic Dairy Report was released on September 6, 2024. The Vermont Monthly Organic Dairy Report covering June 2024 showed the weighted average price for fluid milk decreased from May, while the total volume and average daily production per cow also decreased. The USDA AMS National Organic Program (NOP) Organic Insider sent out on August 30th discussed an upcoming meeting of the National Organic Standards Board (NOSB) in Portland, Oregon in October 2024. Monthly export volumes for organic milk during July 2024 were up from the month prior, and up from July 2023. Total organic dairy ads increased in the week 36 retail ad survey. Every organic commodity present in last week’s survey, except sour cream, appeared in more ads this week. This week’s most advertised organic dairy product was milk. Organic cottage cheese, cream cheese, and ice cream appeared in this week’s retail ad survey after not being present last week.

US RETAIL REPORT: Conventional dairy advertisement totals slid 11 percent lower, while organic retail dairy ad totals increased 42 percent during week 36. Conventional ice cream, in 48-to-64-ounce containers, for the second consecutive week was not the most advertised dairy item, as that item’s ad totals decreased 43 percent from last week. Conventional sliced cheese in six-to-eight-ounce packages was the most advertised item this week, while half-gallon milk returned to its normal top spot among organic dairy items, after a 65 percent increase from last week’s ad totals.





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China yellow broiler production decline bottoming out – GAIN

Live poultry market closures led to a decline in 2019


13 September 2024


2 minute read

China’s USDA post forecasts yellow broiler production in 2025 will be nearing the end of its decline and be relatively stable, according to a recent US Department of Agriculture (USDA) Global Agricultural Information Network (GAIN) report. Yellow broilers previously dominated the market and flocks were maintained with domestic genetics. Due to live poultry market closures – the major market platform for yellow broiler sales – yellow broiler production has been in decline since 2019 and accounted for less than 30% of the market in 2023.

According to industry sources, yellow broiler production continued to decline through the first half of
2024. Though some large-scale producers increased production, a greater number of producers have
lowered production or exited the market. Lower production volumes have resulted in higher yellow
broilers prices in the first half of 2024. Due to higher yellow broiler prices and lower feed costs (see
Chart 2), operations have generally become profitable in 2024.

In China, there are three large-scale, publicly traded yellow broiler breeding companies. According to
their 2024 semi-annual financial reports, all the three are profitable and one reported almost 200%
year on year profit growth. The three large-scale companies continued expanding production while small- and medium-sized yellow broiler producers exited the market. The total market share of the three producers was estimated at 50% in 2023 and post forecasts the overall production of the three producers will continue to expand in 2025. In the second half of 2024, there are more holidays and periods of increased consumption.

Assuming no outbreaks or shocks to feed prices or large capital expenditures, the companies should
remain profitable through 2024 and will continue to gain market share. Post forecasts production gains in commercial operations will be offset by shrinking production volumes of numerous smaller producers, resulting in a bottoming out of the decline in total yellow broiler production in 2025. Smaller producers seemingly have lower production efficiencies and increased costs and some challenges meeting environmental regulations. Also, many of the smaller firms reportedly had prolonged losses in 2023 and less financing available to them to weather the difficult market conditions.





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Brazil chicken meat exports reach highest average price in two years

Average value of exports exceeds $200,000 dollars/ton


13 September 2024


2 minute read

The average price of Brazilian chicken meat exports exceeded the level of $2,000 per ton, according to a survey by the Brazilian Animal Protein Association (ABPA). In August, the average price per ton exported reached US$ 2,089, 8.9% higher than that recorded in the same period last year, of $1,918. It is the highest average price since August 2022, at $2,106 per ton.

In total, 379.8 thousand tons were shipped in August, a volume 12.3% lower than in the same period last year, with 433.3 thousand tons. In revenue, the drop was smaller, 4.5%, with $793.6 million recorded in August this year, against $831 million in the same period last year. Revenue in Reais grew 8.1%, with R$4.406 billion in August this year, against R$4.074 billion in the eighth month of 2023.

In the year (January to August), the volume of chicken meat shipped reached 3.432 million tons, a volume 1.8% lower than the same period last year, with 3.495 million tons. Revenue recorded in the first eight months of 2024 reached $6.319 billion, a balance 7.8% lower than the same period last year, with $6.858 billion. Revenue in Reais accumulated in the year totaled R$33.004 billion, a balance 4.1% lower than the previous year, with R$34.412 billion.

“The flow of shipments recorded so far follows a monthly average equivalent to that of the 12 months of 2023, settling at around 430 thousand tons,” said Ricardo Santin, president of ABPA.

In the survey by destination, the United Arab Emirates took first place, with 39.2 thousand tons imported from Brazil in August, a figure 17% lower than in the same period last year. At a different pace, shipments to Japan grew 32%, reaching 39 thousand tons. Next came South Africa, with 28.1 thousand tons (+11%), Saudi Arabia, with 26.9 thousand tons (-28%) and China, now in fifth place, with 16.3 thousand tons (-69%).

In the survey by state, Paraná continues to lead exports, with 161.2 thousand tons exported in August (-2.7%), followed by Santa Catarina, with 84.2 thousand tons (-14.1%), Rio Grande do Sul, with 37.8 thousand tons (-42.5%), São Paulo, with 23.8 thousand tons (-3.1%) and Goiás, with 17.8 thousand tons (+4.3%).

“The average price was strongly influenced by the growth in shipments to high value-added markets, such as Japan,” said Santin. “On the other hand, there was a loss of shipping windows in certain ports, especially in Paranaguá, where there is a large backlog of logistics flow. Specific effects of Newcastle Disease also contributed to the lower result, especially in shipments to China and Mexico.”





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Hy-Line shares technical expertise with US visitors

New vitamin and trace mineral recommendations discussed


12 September 2024


1 minute read

In June, Hy-Line had the honor of hosting 90 U.S. commercial egg managers, veterinarians, and nutrition experts in central Iowa as part of Hy-Line North America’s technical school. Hy-Line International technical and research staff alongside Hy-Line North America technicians presented on various topics, including nutrition, egg quality, genetic improvements, and lighting at Hy-Line’s Dallas Center campus, as well as the Iowa State University Feed Mill.

Technical School attendees visited the Iowa State University Feed Mill

Global Technical Services Manager Vitor Arantes explained new vitamin and trace mineral recommendations along with a phase feeding program for Hy-Line varieties. Dr. Kaylee Rowland shared genetic improvements in egg quality which drive Hy-Line varieties to match market demands of birds through long 100-week cycles.

These include maintaining strong shells; optimizing egg shell color; and the measurement process that supports Hy-Line’s industry-leading internal egg quality. Diagnostics Laboratory manager Stephanie Schultzen discussed the testing done on Hy-Line and customer flocks for maintaining and supporting top health status. 

Stephanie Schultzen explained the Diagnostic Lab’s testing capabilities

Dr. Ian Rubinoff and Darrin Eckhard of Hy-Line North America presented the science of the chicken’s ability to perceive different day lengths, color, and intensity of lighting, and how it affects productivity and egg weight profiles.

Dr. Ian Rubinoff and Darrin Eckhard led a lighting lab demonstration

Hy-Line values these customer interactions as the valuable feedback assists us to adjust our approach and properly apportion trait selection emphasis to continue to provide the laying hens which most closely match the environmental conditions in the field and customer requirements.





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Immune-complex vaccines pair with vector vaccines to cool IBD challenges

Reasearch and methodology behind immune-complex vaccines for IBD


11 September 2024


3 minute read

When it comes to protecting flocks from infectious bursal disease (IBD), poultry producers and veterinarians have several strategies available, including immune-complex vaccines that may be included in a rotation strategy with recombinant HVT-IBD vaccines.

Immune-complex vaccines provide unique attributes in the IBD protection toolbox. These vaccines contain an IBD virus vaccine coated by antibodies, which must first degrade before the vaccine virus is released in the bird, delaying the stimulate a robust immune response compared with classic live vaccines.

Often used in cases of high field-virus pressure, immune-complex vaccines are useful for “cooling down the house” and keeping the field pressure low for subsequent flocks, said Leticia Frizzo da Silva, DVM, PhD, senior principal scientist, Zoetis.

They do this by colonizing the bursa and blocking early replication of the field virus. The introduction and repeated use of immune-complex vaccines can repopulate a house with the vaccine virus, creating a “diluting” effect, she added.

Over time, this approach can replace the field virus to the point where the farm mostly has the vaccine virus.

Vector and live vaccine comparisons

Because of the way the immune-complex vaccine is manufactured, it cannot be immediately neutralized by maternally derived antibodies as conventional live vaccines can, said Frizzo da Silva.

This delayed release brings at least three major advantages:

  1. The robust vaccine-induced active immune response reduces the high chance of neutralization of vaccine virus by maternal antibodies.
  2. The onset of immunity is naturally adapted to when each individual bird is ready to respond, due to the active vaccine-induced immunity starting as passive immunity decreases.
  3. The immunosuppression often seen with the use of conventional live vaccines is reduced.1 Whether the birds are vaccinated in ovo or at day of age, the immune-complex vaccine gradually dissociates in the bird’s body and releases the live vaccine virus, which stimulates a robust immune response without being immediately neutralized by maternally derived antibodies.

Vectored IBD vaccines – based on herpesvirus of turkey (HVT) – and immune-complex vaccines have complementary roles. While vectored HVT-IBD vaccines cushion the bursa better and tackle clinical disease effectively, they cannot replace field virus to reduce the environmental load or lower the overall infection pressure in the long run. This makes rotation of the two approaches a sensible option, said Frizzo da Silva.

Options for different field scenarios

The IBD virus is genetically diverse, with seven different genogroups falling into classical virulent, antigenic variant and very virulent types.2 Different field challenges can call for different immune-complex formulations.

A Zoetis vaccine based on the Winterfield 2512 classical virus strain is one such formulation, which has been tested against a high, early IBD challenge, she said.

Another alternative is an immune-complex vaccine based on the V877 IBD strain, which is also considered intermediate plus and distinctly categorized as Genogroup 7,2 Frizzo da Silva added. This option brings a unique mix of efficacy and safety, based on additional research.

A rotation strategy of immune-complex and vector vaccines could offer an option for controlling IBD. In broiler chickens, immune complex vaccines based on the Winterfield 2512 strain and the V877 strain can be used, while the V877 strain can be used in layer chickens.

Reach out to your Zoetis representative to find out more.

References
References
1 Muniz EC, Ressende MS, et al. Histopathology and serology reaction to an immune complex infectious bursal disease vaccine (V811 strain) in SPF and commercial birds. ARS Veterinaria. 2018;34(2):69-76. AR-20693.
2 Michel LO, Jackwood DJ. Classification of infectious bursal disease virus into genogroups. Arch Virol. 2017;162:3661-3670. AR-13682.





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AAAP: Novel APEC serogroup pathogenicity

Novel APEC serogroups O152 and O145 caused the highest embryonic mortality


11 September 2024


2 minute read

[Excerpts of a poster presentation by Klao Runcharoon and colleagues, Department of Population Health, College of Veterinary Medicine, University of Georgia, during the 2024 annual conference of the American Association of Avian Pathologists]

Avian Pathogenic Escherichia coli (APEC) causes colibacillosis resulting in systemic or localized infections in poultry including airsacculitis, septicemia, pericarditis, perihepatitis, salpingitis, and cellulitis. Serogrouping based on the detection of somatic O-antigens is a useful tool to classify APEC and relate to disease pathogenicity. There are approximately 188 E. coli serogroups and the most common types associated with colibacillosis include O1, O2, and O78.

However, our APEC collection from avians diagnosed with colibacillosis in Georgia poultry populations has identified emerging serogroups with limited information on their pathogenicity. Therefore, the pathogenicity features of these emerging serogroups were evaluated using multiple approaches including the serum resistance assay, embryo lethality assay, and chick challenge assay.

We selected 10 novel APEC strains from our collection which included serogroups O25, O15, O91, O152, O161, O86, O88, O115, O62/O68 and O45. We tested their ability to grow in chicken serum in 96 well-plates. A bacterial suspension was added to the chicken serum and adjusted to a concentration of 106 colony-forming units (CFU/mL). Serum was removed from each well at 0 and after 4 hours incubation at 40◦C. The suspensions were diluted and plated and the CFU was determined after 24 hours of incubation. All selected APEC serogroups except O25 were resistant to serum.

For the assay, 12 day of age embryonic eggs were injected with 300-500 CFU/0.1 mL of each strain via the allantoic fluid. Embryos were candled daily for five consecutive days, and deaths were recorded. The results showed that the highest mortality (100%) was found for APEC serogroups O152 and O145, while O88 caused only 50% mortality. Further assessment of the pathogenicity in chicks was also performed using a chick challenge assay. Twelve one-day-old chicks per group were inoculated subcutaneously with 108 CFU/0.1 mL of the bacterial strain. Times of death and clinical scores were combined to give pathogenicity scores.

E. coli isolates that killed >50%, 10%-50%, and 0-10% of chicks were considered as virulent, moderately virulent, and avirulent, respectively. Analysis found that O15, O91, and O88 had significantly lower (p< 0.05) pathogenicity scores than the positive control group APEC O18. Serogroups O25, O152, O115, and O45 had numerically higher pathogenicity scores than the positive control group.

Overall, the novel APEC strains exhibited different degrees of pathogenicity in both in vivo and in vitro assays. Some strains showed high virulence in all assays while some were less virulent warranting further investigation of their pathogenicity in older birds to establish new protection plans against these emerging serogroups.





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