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Better Intestinal Integrity improves ADG and FCR by increasing digestion and nutrient intake while reducing energy waste.

Gut health and Intestinal Integrity (I2) support bird and flock production efficiency. The the core functions of the intestinal tract are digestion, secretion, nutrient absorption and nutrient transport. Disrupting the function of the intestinal system inhibits performance, average daily gain and feed conversion.  
Good intestinal health:
  • Supports uptake of needed nutrients
  • Promotes optimal bird growth and weight gain
  • Encourages efficient energy use and reduces the need for internal repair
  Intestinal Integrity (I2) snapshot: 2020
  • Globally birds had a mean score of more than 95 (out of 100)
  • 90% of birds scored above 90 but the lowest score was 23.84
  • 25% of birds had almost perfect scores 98-100


Intestinal Integrity (I2) Index

The Intestinal Integrity (I2) index is a weighted report, unique to HTSi, that analyzes the overall intestinal health of flocks. The index can function as a driver of broiler health and performance as a link has been established between better Intestinal Integrity and improved average daily gain (ADG), feed conversion ratio (FCR) and European production efficiency factor (EPEF).3 The score established in the I2 index is based on evaluation of 23 key lesions reviewed, including coccidia, during healthy bird necropsies. Data from the lesions tracked are used to calculate an I2 score and provide performance indicators to producers. A perfect Intestinal Integrity (I2) index score of 100 means no potential loss from gut health was detected. The review also monitors intestinal health over time, which allows interventions to be employed, and can be used to establish what is “normal” for an area, farm or season.



A perfect Intestinal Integrity (I2) index score of 100 means no potential loss from gut health detected at this time.



Intestinal Integrity (I2) in-depth (I2 for 10 years)

Globally, Intestinal Integrity (I2) have averaged 94.97 for the last 10 years, however, during that period regional results were bookended by Asia Pacific and Latin America on the low and high sides, respectively.

In the last 10 years measures of intestinal health demonstrated the consistency producers in different parts of the globe are experiencing. Producers in several regions have witnessed slight improvements in gut health year by year, while those in Asia Pacific have seen the most positive development.



Asia Pacific producers have seen the most consistent improvement in the last decade, while other regions presented more consistency and smaller, slower improvement from 2010. However, some regions like North America and Europe, Middle East, and Asia saw peak performance at the mid-point of the decade.



I2 by bird age

Bird Intestinal Integrity (I2) can be influenced by age as some intestinal diseases occur earlier than others.

Birds tracked using the HTSi system can vary in age. Bird information is recorded on about day 26 of production. However, in 2020, the information posted applied to birds ranging from 5 days post-hatch to 65 days old. Bird age can influence health tracking as some diseases occur earlier or later in production and I2 index tend to decline from days 0-25 before leveling off. However, some regions will see continued decline further into the production period.



Bird health tends to vary wildly toward the end of the production period when new disease outbreaks can occur. This could bring particular challenge for producers working with slow growth birds.





While gut health tends to decline until birds reach about 30 days of age, extreme variation at the end of production cycles could indicate new disease breaks and provide particular concern for producers in Europe, Middle East and Africa and Asia Pacific. Lesion scores for E. acervulina, E. maxima, E. tenella and E. necatrix range from 0-4 where 0 indicates no lesion.



Coccidiosis damage

Coccidiosis is one of the most expensive broiler diseases, potentially costing global producers up to £13 billion ($18.1bn) annually.2 Coccidiosis is a major driver of intestinal damage present in multiple geographic regions. Unfortunately, attempts to eradicate the disease have not been successful. Its presence is linked to reduction in bird performance and reductions in welfare, which make the disease an ongoing concern. It also has been tied to the development of necrotic enteritis. It is considered one of, if not the most, costly disease faced by poultry producers. In 2016, it was calculated that the total losses for producers in the UK was £99.2m ($138.1m) and, on a more global level, ranged from £7.7-£13 billion ($10.7 - $18.1bn) based on losses in three areas:2

  • Losses due to mortality
  • Losses from decreased final bird weights
  • Losses due to worse feed conversion

Coccidiosis in-depth

Three strains of coccidia – Eimeria acervulina, E. maxima and E. tenella – cause the majority of problems for producers globally, while a fourth – E. necatrix – brings challenges to producers in Asia Pacific.

While coccidia overall presents a primary challenge for poultry producers, the four main strains of the pathogen appear with differing frequency and severity depending on region. Each coccidia strain generates distinct lesions and targets specific sites in the gut, which can be used to identify the strain and assess severity of the infection.



Lesion scores for E. acervulina, E. maxima, E. necatrix, and E. tenella range from 0 - 4 where 0 indicates no lesion.



The four main strains include:

  • Eimeria acervulina generates white, plaque-like lesions in the duodenum and interferes with FCR. It is most common in Europe, Middle East and Africa where it affects almost 30% of birds. It also is the most common strain of the disease found in the region most sensitive to coccidiosis overall – almost 52% of birds display signs of the disease. The strain also has been linked more often to more severe lesions than others and is one of the quickest to develop.
  • Eimeria maxima is the largest species allowing it to develop deeper in tissues and cause localized hemorrhages and it inhibits FCR. It has been found in multiple regions, but it causes the most challenge for producers in the Asia Pacific region., where more than 18% of birds are affected, followed by those in Europe, the Middle East and Africa, where about 15% are. This strain of the disease also peaks later in the production cycle – 30-40 days – meaning it could be more of a problem for producers working with slower-growing birds.
  • Eimeria necatrix only affects about 3.4% of birds in the Asia Pacific region. However, it is not found so commonly in other areas. The strain typically is found later in the production cycle as it appears after day 40 and may be more of a problem for slower-growing birds.
  • Eimeria tenella  causes lesions in the cecal pouches. It has the highest pathogenicity at the bird level. It has limited presence in North America – where less than 1% of birds are affected by it - compared to other parts of the globe. It is most common in Asia Pacific, where it troubles less than 1/6 of the birds tracked.


The presence of specific strains of coccidiosis brings different challenges for producers based on where they are raising birds and the production methods being used.



Coccidiosis throughout the year

Most regions show consistent levels of intestinal health throughout the year. However, Asia Pacific tends to see a peak in E. Maxima in early summer while Europe, the Middle East and Africa and North America see higher levels of E. acervulina throughout the year.

Coccidia remain a common challenge for poultry producers throughout the year and many regions see consistent levels of challenge regardless of disease strain or season. However, producers in North America and Europe, the Middle East and Africa may face additional challenges at specific times. Assessing mean Intestinal Integrity (I2) data month by month for a period of several years highlights the need for additional proactive interventions during early spring for – for Europe, the Middle East and Africa and North America - and in June for the Asia Pacific region.



Both Europe, the Middle East and Africa and North America tend to see higher average levels of acervuline regardless of month, but producers in all regions indicate that coccidiosis remains a year-round challenge.



I2 Beyond coccidiosis



Lesion scores for Feed Passage, Watery Content, Cellular Sloughing and Mucus range from 0 - 1. A "0" score indicates no presence of the condition. A score of "1" indicates the presence of the condition. For more on each lesion, see detailed information below.



In addition to cocci, there are other challenges that cause damage to I2 and carry identifiable pathology, even if the root cause is harder to track. Some of these include cellular sloughing, excessive intestinal fluid or watery content, and gizzard erosion.

About Cellular Sloughing (CS)

HTSi® definition

Presence of excessive cellular debris in the proximal intestine. It may be mixed with excessive mucus. Typically a white pasty consistency in the proximal intestine and it may be mixed with orange digested mucus more distally.

  • Score 0. Absence of the condition
  • Score 1. Presence of excessive cellular debris in the proximal intestine, possibly mixed with excessive mucus.




Looking region by region, producers in Asia Pacific and Latin America have been lowering scores from cellular sloughing.



About Excessive Intestinal Fluid (WC)

HTSi® definition

The presence of excessive fluid in the intestinal tract upon opening, or noticeably increased content in droppings. It may be evaluated by other diagnostics.

  • Score 0. Absence of the condition
  • Score 1. Presence of excessive fluid in the intestinal tract, or noticeably increased content in droppings.




Producers in NA and Asia Pacific have more room to improve in dealing with generation of watery content, however, Latin America and Europe, the Middle East and Africa have demonstrated more success.



About Gizzard Erosion (GIZ)

HTSi® definition

Examination of the gizzard lining for evidence of erosions and ulcerations. Even though the lining of the gizzard is very tough, certain toxic compounds associated with feed can erode it. Biogenic amines result from spoilage or improper processing of certain proteins, especially meat meals and fish meals. Increased amounts of copper sulfate can increase gizzard erosion. Ingredient quality is the most effective strategy in prevention of gizzard erosion.





While the Asia Pacific region has seen improvement in average GIZ lesion scores, Europe, the Middle East and Africa have seen a steady increase in average lesion score.



About Intestinal Mucus

HTSi® definition

The presence of excessive mucus in the intestine. Although mucus production is a normal digestive function, certain disease agents (coccidia, bacteria, viruses) and feed toxins can stimulate excessive mucus production. Research has shown that Clostridium perfringens, the leading cause of necrotic enteritis, can use mucus as a growth medium and energy source, further exacerbating bacterial enteritis.

  • Score 0. Absence of the condition.
  • Score 1. Presence of excessive mucus in the intestine.




Looking at mucus as an indicator of intestinal health indicates that producers in several regions have more work to do.



About Feed Passage

HTSi® definition

The presence of undigested feed in the large intestine or feces, comprising greater than 25% content. Feed passage is an indicator that digestion is sub-optimal or transit time is too fast and adversely affects caloric conversion.

  • Score 0. No presence of undigested feed at the end of the gastrointestinal (GI) tract.
  • Score 1. Presence of undigested feed in the large intestine or feces, comprising greater than 25% content.




Mucus production and feed passage are indicators of intestinal health, which have been trending negatively for producers in some regions even as Asia Pacific and Latin America regions improve.



Evaluating necrotic enteritis

HTSi® definition

The diagnosis of necrotic enteritis due to Clostridium perfringens. Clinical necrotic enteritis results in substantial intestinal erosions and can lead to marked increase in mortality. The performance and financial significance is readily recognizable. These clinical flocks will also suffer from uniformity issues due to high levels or morbidity. Subclinical necrotic enteritis presents the larger challenge for the poultry industry. This condition develops from compromised Intestinal Integrity and reduces performance without overt signs or mortality or even morbidity.

  • Score 0. No presence of undigested feed at the end of the gastrointestinal (GI) tract.
  • Score 1. Presence of undigested feed in the large intestine or feces, comprising greater than 25% content.


There are regional variations in the levels of Necrotic Enteriris reported across the last decade, however most regions are seeing improvement.






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