Lameness is a growing problem in modern poultry production that decreases bird performance and operation profitability. One of the major contributors to the worldwide poultry lameness issue is Bacterial Chondronecrosis and Osteomyelitis (BCO). BCO typically affects at least 1.5 percent of heavy broilers after 30 days of age, and an epidemic outbreak can impact up to 15 percent of a flock.
What is Bacterial Chondronecrosis with Osteomyelitis (BCO)?
BCO is caused by a bacterial infection in sites prone to microfractures (technically known as osteochondrosis), such as the proximal femoral and tibial growth plates, the radial zone supporting the growth of articular cartilage and the flexible thoracic vertebrae that are typically subjected to extreme torque and mechanical stress. The rapid growth of the bird within the first 30 days of life requires consistent and strong growth plates and articular cartilage. If there are not enough nutrients at the right time or trauma is accumulated this could results in thick, fragile growth plates that are susceptible to osteochondrosis, leading to a bacterial infection of the bone. Typically, the infection reaches these susceptible growth plates via pathogens that circulate in the blood stream after penetrating the gastrointestinal tract or respiratory system.
The infection restricts the birds’ natural movement, often reducing feed and water intake, and is a significant factor in morbidity and mortality. BCO often requires the use of an antibiotic treatment strategy, but recent research also concludes that a healthy gastrointestinal tract may help prevent or limit BCO.
Dr. Robert Wideman Jr. with the Center of Excellence for Poultry Science at the University of Arkansas is a widely recognized expert on BCO. He created a mechanical stress model using wire flooring to demonstrate the role stress, footing instability and a weak immune system can play in the development of BCO.
“BCO is a devastating lameness issue,” says Dr. Wideman. “The birds go from being clinically healthy one day to showing a hesitancy to stand up the next day. In three to four days the bird is completely incapacitated and upon post-mortem examination, they have large bacterial abscesses in the femoral head, tibial head and vertebrae.”
Significant mortality occurs starting around day 28, meaning the poultry operation is not only losing birds due to the infection, but these birds have consumed considerable feed and that is also a cost to the operation.
Strategies to Help Prevent or Manage BCO
Management is key. Poultry producers need to increase flock monitoring activities since BCO spreads rapidly, and take steps to enhance overall flock health.
“Recent epidemiological evidence suggests many BCO outbreaks are initiated by low-level vertical transmission of pathogenic bacteria, followed by a horizontal bird-to-bird spread in the broiler house,” says Dr. Wideman. “It appears very likely that in many cases the newly hatched chicks are carrying BCO pathogens from the hatchery to the broiler barns.”
This means hatchery sanitation is important in preventing potential contamination of the chicks. Floor eggs and soiled eggs should never be sent to the hatchery. Hatchery temperature management pre- and post-hatch must be monitored, as heat stress in the hatchers or post-hatch can make chicks more susceptible to BCO. Excessively high brooding temperatures also have been associated with subsequent susceptibility to BCO.
Dr. Wideman also recommends newly hatched chicks taken directly from the hatchery should be evaluated for existing femoral head necrosis and bacterial contamination of the spleen, as these are indices of vertical transmission.
Once the chicks are in the broiler house, it is important to focus on water quality and sanitation, as pathogens linked to BCO can be present as biofilms in water lines and drinkers. Maintaining excellent litter quality is important, as footing instability — demonstrated in Dr. Wideman’s research — can lead to growth plate micro-trauma and subsequent bacterial infection in the growth plates.
Poultry Nutrition can Reduce Spread of BCO
Since BCO follows a horizontal bird-to-bird spread, this requires an oral ingestion of bacterial pathogens — mainly from excreta in the litter but perhaps also from contaminated drinkers or nipples — followed by colonization of the bacteria in the gastrointestinal tract and translocation across the intestinal epithelium into the blood stream.
The lining of the intestinal tract is comprised of a layer of epithelial cells. These cells are bound to each other by complex protein structures, the main ones called “tight junctions,” and their role is to prevent bacteria, pathogens and toxins from passing through the intestinal lining and into the bloodstream.
Factors, such as heat stress, bacteria, feed contaminants, etc., can weaken the quality of the tight junctions, leading to a syndrome called “leaky gut.” This negative impact — leaky gut — allows molecules such as bacteria, pathogens and their toxins to pass in between the epithelial cells, resulting in cell damage or inflammation of the intestine.
Dr. Wideman’s research has revealed that probiotics and trace minerals help to tighten these cell junctions limiting the translocation of the bacterial pathogens from the gastrointestinal tract into the blood stream. Probiotics can reduce the vertical transmission of pathogens by broiler breeder hens, thereby reducing the likelihood that chicks will carry those pathogens into the broiler barns.
Performance trace minerals, such as zinc, copper and manganese also reduce the susceptibility of broilers to BCO by improving the tight junction integrity of the epithelial cells in the gastrointestinal tract and by helping to provide a more rapid immune response to the presence of bacterial pathogens.
In addition, extracellular copper is a key co-factor required by the enzyme Lysyl oxidase that is responsible for crosslinking — strengthening — collagen fibers within the cartilaginous portions of the growth plates. Zinc and manganese also play important roles on bone matrix formation and bone remodeling. Research also indicates that enhanced collagen crosslinking leads to lower incidences of osteochondritic micro-fracturing, and thus fewer wound sites available in the growth plates for bacterial infection. Dr. Wideman’s research also indicates that lower BCO lesion severity scores typically are observed when broilers are provided performance trace minerals.
To learn more about inflammation in poultry and how it may impact your operation, contact your Zinpro representative today.
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