Formulation Insights for Broiler and Layer Nutrition

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Introduction      

The field of poultry nutrition has dramatically evolved from backyard practices to sophisticated, computer-controlled systems, driven by the identification of individual nutrients and their metabolic roles. Since the 1950s, significant strides have been made in protein nutrition, focusing on digestible amino acids, and metabolizable energy (ME) has been a key concept since the 1940s (Elwinger et al., 2016).

The primary goal of broiler nutrition is to meet the increasing nutrient demands of modern genotypes to maximize their productive potential. While agencies like the Agricultural Research Council (ARC) and National Research Center (NRC) historically provided nutrient requirements, breeder companies now largely recommend nutritional specifications for their high-producing strains.

Modern Broilers

Modern broilers exemplify this genetic advancement: in 1957, a 42-day-old broiler weighed 586g with a 2.8 FCR, whereas today it reaches 2,900g with an FCR under 1.70. This remarkable progress underscores the critical role of precise nutrition in realizing the birds’ full genetic potential.

Nutritional Development

Conventionally, poultry nutrition focused on basic nutrients like energy, protein, and phosphorus. However, with fast-growing strains, the focus shifted to amino acid composition and the ideal protein concept, allowing for more targeted formulations and the use of unconventional protein sources. Despite inconsistencies, metabolizable energy (ME) values remain standard for energy content.

Given the emphasis on body weight gain, digestive efficiency has remained largely unchanged (Tallentire et al., 2016), but the gut size relative to the bird’s mass has decreased. As feed is a major cost, the poultry industry urgently needs sustainable and innovative practices to conserve resources and improve nutrient utilization for both protein and energy. Inefficient nitrogen utilization poses a serious environmental concern due to water pollution and soil acidification (Bouwman et al., 2002; Méda et al., 2011).

How Broiler Nutrition has changed:

Broiler nutrition has shifted significantly worldwide, including in India, with substantial changes in nutrient specifications, ingredients, and additives due to increased genetic potential and reduced marketing age (Aftab U 2019). To optimize feed costs without compromising performance, strategies are being incorporated. The expert team, for instance, provides extensive feed formulations, observing trends in cost optimization, balanced nutrient levels, and sustained profit margins. A few of the salient features observed while evaluating these formulations are depicted below:

Broiler Nutrition Evolution: Key Segments

1. Breed/Strain:

• Indian market dominated by high-yielding strains: Ven Cobb, Ross, and Hubbard (over 90%).
• These strains require nutrient-dense feed (amino acids, ME).
• Ross strains generally have higher nutrient recommendations from breeders.
• Ven Cobb can perform well on slightly lower diet densities, though it may extend marketing age and FCR, a strategy used for cost optimization in volatile markets.
• Amino acid fluctuations impact performance more than ME fluctuations.
• High nutrient densities can cause metabolic disorders (ascites, visceral gout), requiring careful adjustment.2. Environmental Diversity & Geographical Locations:

• Climate Adaptation: India’s diverse climate (extreme summer >45⁰C, winter <2⁰C) necessitates significant dietary adjustments for broilers, including nutrient levels, electrolytes, and specialized additives to manage heat and cold stress.
• Dietary Electrolyte Balance (dEB): It measures important electrolytes in the diet – sodium (Na), potassium (K), and chloride (Cl) which is critical for maintaining osmotic pressure and acid-base balance, especially in high temperatures/humidity when panting causes respiratory alkalosis. Optimal dEB values of 240 (mEq/Kg) prevents poor FCR, low body weight, leg weakness, increased fecal moisture, and metabolic disorders like ascites or bone or eggshell quality.

Geographical Variations in India:

• Diet Density: Highest in South, then West, East, and North (descending order).
• Nutrient Levels (ME & Digestible Lysine): Average difference of 20-30 Kcal/Kg ME and 5 points Digestible Lysine between regions, with highest levels in South and lowest in North.
• Dietary Costs: Highest in South, least in North.
• Alternate Ingredient Usage: More prevalent in North (10-15% alternate protein and 20%+ alternate energy) and East (e.g., 7-10% alternate protein and 10-20%+ alternate energy), minimal in West and South. This includes protein alternates like MBM, Rice DDGS, Maize Gluten, Poultry Meal, Deoiled cakes, and energy alternates like Bajra, Jowar, Broken Rice, and Wheat.
• Enzyme Matrix Application: Northern India often considers maximum enzyme matrix (ME, CP, Dig AA’s, Ca, Av P, Na) near product claimable values, followed by East, West, and finally South, where enzymes are mostly applied on top.
• Nutrient Wastage: Highest in South, then West, East, and North.
• FCR (Feed Conversion Ratio): Generally similar across regions (1.55-1.65 for 2 Kg body weight), despite integrators dominating East, West, and South. High market competition in North leads to least-cost broiler and layer diets.

3. Cost Optimization

Feeding represents the largest single expense in broiler production, directly impacting profitability (Tahir et al., 2012). In India, broiler feed primarily uses corn and soybean meal, but their rising prices, with soybean meal nearly doubling, have severely squeezed profit margins for producers.

• Alternate Feed Ingredients
• To combat high costs, the industry explores “non-conventional” feed ingredients as alternatives to expensive corn and soybean meal. These include Distiller’s Dried Grains with Solubles (DDGS), mustard deoiled cake (MDOC), sunflower deoiled cake (SFDOC), Bajra, and Broken rice. The goal is to incorporate small quantities of these ingredients without negatively affecting bird growth or performance, thereby maintaining feed quality while reducing costs.
• However, these alternative ingredients often contain anti-nutritional factors like Non-Starch Polysaccharides (NSPs) and phytate, and alternate protein sources can have low protein digestibility.
• NSPs (e.g., arabinoxylans, β-glucans, pectins) increase digesta viscosity in the intestine, reducing contact between endogenous enzymes and nutrients. It reduces the digestibility and limits the apparent metabolizable energy (AME) (Kocher et al., 2003). This impairs the digestibility of starch, proteins, and lipids, leading to reduced performance and apparent metabolizable energy (AME). Increased viscosity also alters the gut ecosystem (Choct et al., 1996), promoting fermentative microflora (Wagner and Thomas, 1978).
• While corn-soybean meal diets have high protein digestibility, non-conventional animal-derived meals often have lower digestibility (Freitas et al., 2011). A wide range of endogenous proteases are synthesized and released in the gastrointestinal tract of the bird, and these are generally considered sufficient to optimize feed protein utilization (Nir et al., 1993). However, some amount of protein passes through the GI tract without being completely digested, (Lemme et al., 2004). Undigested protein reaching the hindgut stimulates the growth of nitrogen-utilizing microbiota (Reid and Hillman 1999), leading to increased levels of toxic compounds like biogenic amines, phenols, and cresols (Apajalahti and Vienola 2016), which negatively impact performance and enteric health (Thomke and Elwinger 1998).

How to Use Alternate Raw Materials Effectively?

• Exogenous enzymes are key to effectively utilizing alternate raw materials and improving nutrient efficiency. Kemin nutritionists use a range of enzymes to unlock nutrients the bird cannot utilize on its own, improving productivity and saving costs.
• NSPases and proteases are crucial. NSPases degrade NSPs by breaking the fibre chains in the cell wall into smaller fragments (Wyatt et al., 2008), reducing intestinal viscosity, and increasing digestibility (Choct et al., 1999).
• Proteases enzymes typically work by hydrolyzing proteins or peptides, thus improving the protein digestibility (Thorpe and Beal, 2001). While endogenous proteases exist, some protein remains undigested. A multi-protease approach (acid, alkaline, and neutral) is more comprehensive due to the two-stage nature of protein digestion (Bedford et al., 2018). A gastric stage occurs in acidic pH via pepsin and the second stage occurs in a neutral environment in the gut via trypsin, and chymotrypsin resulting in faster transit time of digesta (Kamel et al., 2015). A more comprehensive approach is using a multi-protease (acid, alkaline & neutral) which can complement the protein digestion throughout the gut (Chandrasekar et al., 2017). This not only improves protein digestibility but also enhances gut health by reducing undigested protein entering the distal gut, thereby limiting harmful microbial proliferation. The efficacy of protease depends on the ingredients used in the diets (Kocher et al., 2003); diets with less digestible proteins (like DDGS, MDOC) provide more substrate, making protease activity more efficient and contributing to cost reduction.

4. Evolving Nutrient Parameters and Their Impact Over Time

Over the past 10 to 15 years, poultry feed formulation practices in India have significantly evolved, driven by advancements in breed requirements and genetic developments.

Shift in Amino Acid Focus

The focus has largely shifted from crude protein (CP) to digestible amino acids (Dig AAs). Beyond essential amino acids, Serine and Glycine are now considered conditionally essential, especially in low CP diets. Additionally, Isoleucine, Valine, and Leucine have gained prominence alongside previously considered essential AAs. While Dig AA ratios, particularly concerning Dig Lysine, have changed, the ideal AA ratios and the extent of each essential AA in diets have been maintained. Notably, there’s been a significant reduction of 50 to 70 Kcal in metabolizable energy (ME) while maintaining optimal Dig Lysine to Calorie ratios. This adjustment is based on observations that bird productivity and uniformity heavily rely on essential AA inclusion, with slight ME reductions not significantly impacting performance. However, for layers and breeders, ME continues to play a significant role in productivity and uniformity, with less change in ME considerations over the last decade.

Importance of Dietary Electrolyte Balance (DEB)

Dietary Electrolyte Balance (DEB) has emerged as a crucial factor in poultry nutrition over the past decade. There’s been an increase in intracellular electrolytes, specifically sodium (Na) and potassium (K), with minimal changes in chloride (Cl) levels, thereby elevating the overall DEB. For instance, Na levels in pre-starter and starter diets have increased from roughly 0.19% to 0.21% for improved feed intake and conversion (Mustak et al., 2005).

Changing Calcium and Phosphorus Paradigms

The traditional approach of high calcium (Ca) and available phosphorus (Av P) in all broiler and layer diets has been re-evaluated. Research suggests that high levels of Ca and Av P are critical for broiler development only during the first three weeks. Beyond this period, higher levels do not significantly impact performance and can negatively affect the binding of other nutrients, including oil and trace elements (Nollet et al., 2024). Consequently, broiler finisher diets (after week 3) now ideally contain around 0.7% Ca or less and 0.4% Av P or less for better nutrient absorption and performance. Similarly, for commercial layers, the practice of incorporating excessively high Ca levels in phase diets is changing, with ideal limits close to or below 4.1% in phase 1 diets being adopted to mitigate negative effects on energy deprivation (Dijkslag MA et al., 2023).

5. Increased Emphasis on Feed Additives for Gut Health and Meat Quality

The last decade has seen a paradigm shift in the consideration of essential additives for stronger gut health, overall bird health, and immunity across the Indian subcontinent.

Gut Health Focus

• The use of probiotics, including multi-strain varieties, has increased, with Bacillus subtilis species proving particularly predominant and efficacious. Producers are investing in additives like Butyrates, short-chain fatty acids (SCFAs), medium-chain fatty acids (MCFAs), and Glycan products to modulate gut microbiota and enhance intestinal health. Additionally, there’s growing interest in Quinolone molecules (CHQ) and herbal antidiarrheals to regulate digesta flow and prevent non-specific diarrhea. Despite official bans on certain systemic and gut-acting antibiotics like colistin and BMD, some feed manufacturers are judiciously using other Antibiotic Growth Promoters (AGPs) and systemic antibiotic feed supplements on a rotational basis, coupled with proper cocci control programs, to maintain holistic bird and intestinal health.

Improving Carcass Quality

• Over the past five to six years, there’s been a concerted effort to improve carcass quality parameters such as tenderness, juiciness, Myofibrillar fragmentation index, shear strength, and shrinkage loss. Additives that enhance these parameters are now carefully considered, especially for end producers. The use of Betaine as an osmolyte, alongside an improved DEB, is becoming standard industry practice (Ahmad et al., 2006). The judicious use of high-quality probiotics, Selenium, and Vitamin E, coupled with minimal antibiotic use, is also common. Furthermore, Phytobiotics, gut acidifiers, and antioxidants indirectly contribute to better carcass quality. In recent years, an emphasis has been placed on optimizing levels of Lysine, Methionine, Threonine, Tryptophan, and Histidine, given their significant role in breast muscle development. Kemin’s feed formulations are also adjusted to reflect these changes and customer interests.

Conclusion

Based on these recent advancements, the following practical conclusions can be drawn:

• Broiler nutrition has undergone significant changes since its inception, with continuous efforts to precisely match the birds’ nutrient requirements.
• Newer concepts like digestible amino acids, optimal amino acid ratios, and DEB are crucial for maximizing the bird’s genetic potential while ensuring flock livability.
• Broiler nutrition should prioritize cost-effectiveness through innovative approaches, including the use of alternative raw materials, optimized enzyme matrices, and necessary diet density to prevent nutrient leakage and deficits.
• Close attention should be paid to the degradation of anti-nutritional factors in broiler diets to avoid compromising productive performance.
• Correctly considering nutrients that support health and immunity is vital for enhanced productivity and performance, even with lower diet density, leading to optimized costs and sustainability.

References are available upon request.