Introduction
Indian poultry production standards have improved by leaps and bounds in the past decades, a tribute to continuous genetic development, precise nutritional formulations, and improved management practices. However, one issue that has lately gained significant attention from producers is the contraction in profit margins experienced across the categories: Broiler, Breeder, and Layers. This calls for continuous improvements in production efficiency for profitable enterprises, and undoubtedly, the path to this improvement goes through an ‘efficient gut health’ management program. ‘Gut Health,’ a term that emerged about a decade and a half ago in the poultry landscape, today holds more significance than ever before.
In the current context, producers are facing a double whammy to sustain. On one side, the
input factors, particularly the major conventional raw materials, are showing dynamic pricing trends, with associated challenges of availability and desired quality. On the other side, price realization is equally dynamic, eventually putting the producer in a tight spot. The situation becomes even more complicated due to the prevalence of subclinical infections, mycotoxin contamination, deteriorating water quality, and erratic environmental fluctuations.
Does this situation relate to the gut health of our birds? Definitely, yes. The changing trends in formulations, with higher and more diverse usage of unconventional raw materials, increased nutrient demands from birds, and the direct impact of diseases and the environment on poultry gut health, all require attention to specific areas that are impacting our birds’ gut health today. This calls for a sharp focus on the evolving challenges of poultry gut health.
Impending Challenge: Dual Threat of Necrotic Enteritis and Chronic Gut Inflammation (CGI)
Conventionally, Clostridium perfringens has been attributed to the causation of Necrotic
Enteritis (NE) (primarily subclinical, causing a loss of Rs 4-5 per bird), along with Eimeria species, as the primary reasons for gut-associated challenges. However, today the situation is more complicated than just NE due to the higher intensity of predisposing factors for NE, attributed to increased gut stressors. Consequently, increasing gut stressors continue to directly impact the bird by causing chronic intestinal inflammation, resulting in an additional loss of Rs 2-3 per bird. This impact of chronic intestinal inflammation is largely due to the increased demand for nutrients by the bird with chronically inflamed intestines.
Inflammation is the body’s response to any tissue injury. This becomes problematic from a producer’s standpoint when the response is undesired and exceeds the required level. In fact, when this response or inflammation of the intestines becomes a regular feature, often undesirable, it is termed low-grade ‘Chronic Intestinal Inflammation.’ The response comes at the expense of about 0.27 g of ideal protein per bird per day (Sandberg, F. B. et al., 2007; Klasing, K. C., 2007) when measured in simulated models. Translating commercially, the losses could be estimated at about 60g of feed lost per broiler bird.
Undesired intestinal inflammation weakens gut integrity, aggravates dysbiosis, promotes the translocation of pathogens from the gut into the system, and importantly, puts the gut under oxidative stress, further compromising the immune function associated with the gut.
Gut Stressors for NE & CGI (Chronic Gut Inflammation)
Gut stressors’ are factors that induce injury in the intestine, which serves as both a cause
for the further proliferation of Clostridium perfringens (acting as a predisposing factor for NE) and simultaneously results in intestinal inflammation, causing a direct loss of profitability. Broadly, these can be segregated into specific and non-specific causes.
Specific Factors
The pathogens harbored in the gut, both clinically and subclinically, inflict an inflammatory response and act as specific gut stressors. The increasing prevalence of bacterial and viral pathogens poses a challenge to address.
Non-specific Factors
These are the hidden challenges that are generally overlooked as substantial reasons for causing or aggravating gut health issues. Dietary factors are the major ‘gut stressors’ that contribute to chronic gut inflammation (CGI) in poultry. The use of higher and more diverse alternative raw materials, combined with higher diet densities and challenges in raw material quality, could be considered the overall reasons. However, when narrowing it down to specific aspects of poultry diets, the following emerge as major factors contributing to dietary gut stress.
Dietary “Gut Stressors”
- Non-Starch Polysaccharides (NSP)
These are largely the soluble fraction of carbohydrates that increase viscosity and form ‘hydrocolloids’ that cover feed ingredients. Higher digesta viscosity increases the proliferation of gut pathogens like E. coli and Clostridium perfringens, increasing inflammation in the gut.
- Mycotoxins and Pesticide residues
Apart from systemic effects, mycotoxins, even at low levels, damage the intestinal epithelium, induce oxidative stress, and damage junction proteins. Pesticide residues have remarkable cytotoxic effects that complicate the mycotoxin challenge. This damage induces inflammation in the gut, decreases absorption, and causes leaky gut.
Major responsible mycotoxins: Aflatoxin B1 (AFB1), Ochratoxin A (OTA), Fumonisins, and Trichothecenes.
- Proteins & Oxidized Lipids
Higher protein intake is correlated with inducing inflammation in the gut. Putrefactive fermentation, facilitated by higher protein, can produce metabolites such as ammonia and hydrogen sulfide, which have toxic effects on cells. Higher protein from animal-based sources comes with a high glycine content that promotes Clostridium perfringens growth (Necrotic Enteritis), which is highly inflammatory. Poor-quality and oxidized lipids containing peroxide components can damage the gut, resulting in injury and inflammation.
- Anti Nutritional Factors (ANF’s)
Many ANFs, such as enzyme inhibitors present in diets over time, are believed to disrupt digestive metabolism and possibly induce subsequent tissue injury. Higher usage of alternative raw materials and challenged raw material quality indicate the need for a cautious approach to keep gut inflammation in check due to ANFs.
Water Quality as “Gut Stressor”
Often an ignored aspect, deterioration in water quality serves as a definite ‘gut stressor.’ By and large, the impact can be classified into two areas. Firstly, due to the pathogenic load that varies because of management conditions, geography, and seasons, and is heavily influenced by water sanitation practices at the farm level. Secondly, the chemical properties of water (pH and hardness) significantly impact the birds directly by influencing normal physiology, but more importantly, by reducing the effectiveness of the water sanitation program in place. An estimate suggests that currently, the average pH and hardness of water used in poultry farms across India are 7.5 and 650 ppm, respectively, with values soaring as high as pH 8.6 and 1200 ppm in certain regions that have developed into intense pockets of the poultry industry.
Environmental “Gut Stressors”
Erratic fluctuations in the environment, lacunae in management, and intensified production conditions like high stocking densities create oxidative stress and associated gut inflammation.
Paving Further Course in Gut Health Management
Poultry gut health is definitely multifactorial and dynamic, and with time, its management is becoming even more complicated. Now, the influence of gut inflammatory factors is becoming increasingly important, alongside conventional pathogens. But how can we actually identify gut inflammation in commercial flocks? One such approach would be to explore the use of biomarkers. Biomarkers, which are chemicals released due to a damaged gut and can be identified in blood, feces, etc., could provide a broader picture of gut health, along with intestinal lesion scoring. The utilization of relevant biomarkers for commercial conditions and taking appropriate measures accordingly can be a strategy to ensure optimal gut health in poultry.
Moreover, from the perspective of gut health management, it is extremely important to take a holistic view and develop a specific gut health assurance program based on the producer’s needs. This program should focus on the regular monitoring of specific factors affecting the gut and dynamically design strategies to mitigate the challenges. It is imperative to have an in-depth understanding of factors impacting gut health, ranging from raw materials, gut pathogen prevalence, water quality, rearing environment, and associated specific and non-specific causes that influence poultry gut health. Eventually, implementing the correct solutions through specific additives against prevalent gut pathogens and addressing factors that aggravate gut challenges (predisposing factors) could pave the way forward.
Detailed references are available upon request.
