Modern nutritional paradigms in swine production: A comprehensive review of global concepts and their relevance to the Indian Industry

Introduction

The global swine industry has undergone a dramatic transformation over the past few decades, transitioning from the production of slow-growing, fat animals to lean, efficient genotypes bred for maximum meat output and high prolificacy. While this genetic progress has significantly increased productivity, it has simultaneously created complex metabolic demands that traditional "onesize-fits-all" group-feeding strategies can no longer satisfy. In modern production systems, it is now common for hyperprolific sows to give birth to more than 20 piglets, placing extreme metabolic strain on the sow, particularly during the last third of gestation when fetal growth and mammary development accelerate (Feyera et al., 2021; Johannsen et al., 2024a) [2,5] . Past nutritional standards and studies conducted on sows with lower reproductive performance are increasingly viewed as inapplicable to these modern highperformance herds (Johannsen et al., 2024a) [5] . At the center of this nutritional evolution is the concept of precision pig feeding, which represents a paradigm shift toward providing the accurate amount of feed with a tailored composition at the exact time required by each individual animal (Gaillard et al., 2020; Pomar and Remus, 2019; Koley et al., 2023) [3,9,6] . This approach is identified as a breakthrough for sustainability, capable of reducing feeding costs by more than 4.6% and decreasing nitrogen (N) and phosphorus (P) excretion by over 38% (Pomar et al., 2009; Koley et al., 2023) [10,6] . Such efficiency is particularly critical for emerging markets like India, where feed costs represent the maximum input expense (65-75%) and where the industry faces growing environmental challenges, including nitrate pollution of aquifers from pig manure (Pomar and Remus, 2019; Koley et al., 2023) [9,6] . Integrating precision feeding is essential for the Indian swine sector to augment its competitiveness and sustainability while transitioning away from traditional standards, such as the Bureau of Indian Standards (BIS, 1986) [1] , which may not adequately reflect the requirements of modern genotypes (Koley et al., 2023) [6] . Beyond precision delivery, modern nutritional paradigms emphasize the specialized management of critical life stages and gastrointestinal health. For hyper-prolific sows, research indicates that a standardized ileal digestible (SID) lysine intake of 16.0 to 16.7 g/d is required in late gestation to optimize N utilization and maximize backfat gain without the metabolic cost of excessive protein oxidation (Johannsen et al., 2024) [5] . Simultaneously, the weaning transition remains the most critical period in pig management, characterized by "weaning anorexia" and profound morphological changes in the small intestine, such as a 75% reduction in villus height within 24 hours (Hampson, 1986; Zheng et al., 2021) [4,13] . To combat these challenges, www.extensionjournal.com functional feed additives-including protein hydrolysates, probiotics, and exogenous enzymes-are being utilized to restore intestinal balance and enhance nutrient absorption (Zheng et al., 2021) [13] . Furthermore, advanced feed processing technologies, such as particle size optimization (aiming for 485 to 600 μm) and thermal treatments like pelleting or extrusion, are vital for maximizing nutrient bioavailability and managing costs (Rojas and Stein, 2015) [11] . Finally, the role of micronutrients has been re-evaluated; vitamins are now recognized as the "unknown heroes" of swine health, requiring precision supplementation to support immune function and productivity under modern environmental pressures like heat stress, which is prevalent in the Indian climate. This review aims to synthesize these modern nutritional concepts-precision feeding, functional gut health management, advanced sow requirements, and feed processing-while specifically examining their relevance to the Indian swine industry. By bridging global scientific advancements with local production challenges, this article provides a comprehensive roadmap for enhancing both the economic profitability and environmental sustainability of pork production in the region.

Precision Pig Feeding -Individualized Real-Time Nutrition Precision pig feeding represents a paradigm shift from traditional group-based nutritional standards to an individualized, data-driven approach (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . Historically, feeding programs relied on factorial methods, such as those from the National Research Council or the Bureau of Indian Standards (BIS, 1986) [1] , which estimate nutrient requirements for large groups of animals over long production phases (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . However, these "one-size-fits-all" strategies often lead to nutrient excesses or deficiencies, as individual animals within a herd vary significantly in their behavioral and physiological responses (Koley et al., 2023) [6] . The modern concept of precision feeding aims to provide the accurate amount of feed with the exact composition required by each individual pig daily (Pomar and Remus, 2019) [9] . Implementation of this system in commercial farms requires the integration of three core actions: automatic data collection, real-time data processing, and automated control systems (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . Data collection is achieved through an array of sensors, including RFID tags for movement monitoring and noninvasive 3D video cameras equipped with depth sensors to track body weight gain (Koley et al., 2023) [6] . These data are then processed through mathematical models like InraPorc, which predict real-time requirements by combining empirical elements with mechanistic factorial equations (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . Finally, automated feeders mix high-nutrient-dense and lownutrient-dense diets in real-time to match the pig's calculated daily demand (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . The economic and environmental impacts are profound; precision feeding can reduce feeding costs by more than 4.6% while decreasing nitrogen (N) and phosphorus (P) excretion by more than 38% (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . Advanced biological models suggest that excretion reductions could eventually exceed 60% (Pomar and Remus, 2019) [9] . This is achieved by supplying individual pigs with daily customized diets that require less crude protein (CP) than traditionally fed pigs (Koley et al., 2023) [6] . By controlling individual animal variations, producers can drastically reduce the industry's environmental footprint, particularly concerning nitrate pollution of aquifers (Koley et al., 2023; Pomar and Remus, 2019) [6,9] .

Nutritional Management of Hyper-Prolific Sows

Modern swine production is defined by the rise of hyperprolific sows, which frequently give birth to litters exceeding 20 piglets (Johannsen et al., 2024; Zheng et al., 2021) [5,13] . This prolificacy places extreme metabolic strain on the sow, especially during the last third of gestation (day 84 to 108), when fetal growth and mammary development accelerate (Johannsen et al., 2024) [5] . During this phase, it is estimated that sow body weight (BW) increases by 16 kg due to the growth of the conceptus and mammary glands (Johannsen et al., 2024) [5] . If the sow is fed below her nutrient requirements during this window, she must mobilize body protein to support the litter (Johannsen et al., 2024) [5] . Excessive mobilization is associated with an increased weaning-to-estrus interval and reduced litter size in subsequent cycles (Johannsen et al., 2024) [5] . Recent research indicates that multiparous hyper-prolific sows require 16.0 to 16.7 g/d of SID Lysine (Lys) in late gestation to optimize nitrogen utilization and maximize backfat (BF) gain (Johannsen et al., 2024) [5] . While sow BW gain plateaus at 5.63 g/kg of SID Lys, BF gain reaches its peak at a lower concentration of 4.85 g/kg (Johannsen et al., 2024) [5] . Feeding protein in excess of these requirements leads to amino acid oxidation and energy-costly urea excretion, which reduces the energy available for fat retention (Johannsen et al., 2024) [5] . A highly effective strategy is the use of low-protein diets supplemented with crystalline amino acids (cAA) (Johannsen et al., 2024) [5] . By providing essential amino acids like Lys, Met, Thr, Trp, and Val while reducing overall CP, producers can meet the sow's requirements without the metabolic cost of deaminating excess protein (Johannsen et al., 2024) [5] . Research has shown that sows fed high-cAA diets gain more body protein and have significantly reduced urea excretion compared to those on traditional high-protein diets (Johannsen et al., 2024) [5] . This strategy also significantly reduces the climate footprint of the feed by lowering reliance on soybean meal (Johannsen et al., 2024) [5] .

Enhancing Intestinal Health and the Weaning Transition

The weaning transition is a critical period characterized by "weaning anorexia" and severe gastrointestinal challenges (Zheng et al., 2021) [13] . Upon weaning, pigs move from liquid sow milk to solid cereal-based feeds, which often results in depressed growth and diarrhea (Zheng et al., 2021) [13] . Morphological changes to the small intestine are profound; within 24 hours of weaning, villus height can reduce by 75%, leading to a loss of absorptive surface area (Zheng et al., 2021) [13] . Furthermore, weaning compromises the paracellular barrier function by decreasing the expression of tight junction proteins, allowing the entry of www.extensionjournal.com toxins and pathogens into circulation (Zheng et al., 2021) [13] . To mitigate these effects, modern nutrition emphasizes functional feed additives (Zheng et al., 2021) [13] . Protein hydrolysates, such as spray-dried porcine plasma, are highly digestible and enhance barrier function while reducing immune system activation (Zheng et al., 2021) [13] . Prebiotics and probiotics modulate the intestinal microbiota to suppress pathogens like E. coli while stimulating beneficial Lactobacilli (Zheng et al., 2021) [13] . Probiotics improve host health by maintaining epithelial integrity, while prebiotics provide the necessary substrate for beneficial microbial growth (Zheng et al., 2021) [13] . Other critical interventions include organic acids and exogenous enzymes (Zheng et al., 2021) [13] . Organic acids are used to decrease gastric pH, which is essential because the optimum pH for vegetable protein digestion is 2.0-3.5, whereas newly weaned pigs often range between 2.6 and 5.0 (Zheng et al., 2021) [13] . Feed enzymes like xylanases and proteases break down nonstarch polysaccharides and allergenic proteins (such as glycinin in soy), which reduces digesta viscosity and gut inflammation (Zheng et al., 2021) [13] . These interventions are vital for preventing the morbidity associated with early weaning stress (Zheng et al., 2021) [13] .

Advanced Feed Processing Technologies

Feed processing is a critical lever for maximizing nutrient bioavailability, particularly when using high-fiber alternative ingredients (Rojas and Stein, 2015) [11] . Particle size optimization is the first step; reducing the mean particle size of cereal grains increases the surface area for enzyme action, improving the digestibility of energy and starch (Rojas and Stein, 2015) [11] . Research suggests that a particle size range of 485 to 600 μm provides the best balance for nutrient utilization (Rojas and Stein, 2015) [11] . However, grinding grains too finely (< 400 μm) or pelleting finely ground diets can increase the risk of esophagogastric ulcers due to increased mixing in the stomach and faster gastric emptying (Rojas and Stein, 2015) [11] . Thermal treatments such as pelleting, extrusion, and expansion offer further benefits (Rojas and Stein, 2015) [11] . Pelleting uses steam and pressure to create durable feed forms, which can increase feed conversion by 4% to 12% (Rojas and Stein, 2015) [11] . These improvements are largely due to the gelatinization of starch during the heating process, making it more accessible to digestive enzymes (Rojas and Stein, 2015) [11] . Extrusion results in more severe physicochemical changes and is particularly beneficial for ingredients with high fiber concentrations (Rojas and Stein, 2015) [11] . Chemical treatments are also gaining traction for high-fiber co-products (Rojas and Stein, 2015) [11] . Treating cereal co-products with Sodium Hydroxide (NaOH) or ammonia can solubilize hemicellulose and lignin fractions, increasing the energy contribution from fiber (Rojas and Stein, 2015) [11] . While these technologies require careful management to avoid palatability issues, they represent a significant opportunity to improve the digestibility of alternative feed ingredients, thereby reducing reliance on traditional corn-soybean meal diets (Rojas and Stein, 2015) [11] .

Micronutrients

While swine nutrition has traditionally focused on macronutrients like protein and energy, the extreme metabolic demands of modern, high-productivity genotypes necessitate a reevaluation of vitamin supplementation levels (NRC, 2012) [8] . Modern hyper-prolific sows frequently give birth to more than 20 piglets, placing extreme strain on maternal reserves during late gestation when fetal growth and mammary development accelerate (Feyera et al., 2021; Johannsen et al., 2024a) [2,5] . Deficiencies in these essential micronutrients are associated with poor growth performance and increased vulnerability to disease challenges (NRC, 2012) [8] . Specific vitamins play critical roles in supporting health: Vitamin A supports vision and immune function, while Vitamin D3 is essential for bone development and overall skeletal health (NRC, 2012) [8] . Vitamin E acts as a powerful antioxidant, protecting cells from oxidative damage and enhancing the overall immune response (NRC, 2012) [8] . B-complex vitamins, including Niacin, Biotin, and B12, are critical for supporting energy metabolism and enzyme function in rapid-growth animals (NRC, 2012) [8] . Furthermore, ascorbic acid (Vitamin C) is utilized for stress reduction and immune support, as it has been shown to reduce direct and indirect oxidative stress in porcine intestinal cell models (Vergauwen et al., 2015; Zheng et al., 2021) [12,13] . Current advancements in precision nutrition aim to provide updated recommendations based on real-world field pressures rather than traditional static standards (Pomar and Remus, 2019) [9] . Modern challenges such as environmental heat stress increase the animal's metabolic requirements for antioxidant vitamins, necessitating adjustments in supplementation to maintain efficiency (NRC, 2012; Koley et al., 2023) [8,6] . Additionally, feed processing technologies must be carefully managed to ensure vitamin retention and stability against heat and oxidation during pelleting (Lewis et al., 2015a; Rojas and Stein, 2015) [7,11] . Ultimately, precision delivery allows producers to fine-tune vitamin intake to meet the specific requirements of individual animals, reducing environmental waste while maximizing herd productivity (Pomar and Remus, 2019; Koley et al., 2023) [9, 6] .

Relevance to the Indian Swine Sector

The Indian swine industry is transitioning toward highperformance production systems while facing unique local challenges (Koley et al., 2023) [6] . Feed costs constitute 65-75% of total input costs in India, making the adoption of modern nutritional concepts an economic imperative (Koley et al., 2023) [6] . One of the most significant hurdles is the continued reliance on traditional standards like BIS (1986), which may not adequately reflect the metabolic needs of the modern, hyper-prolific genotypes now being introduced into the country (Koley et al., 2023) [6] . Integrating precision pig feeding is identified as an essential means to augment competitiveness and sustainability in India (Koley et al., 2023) [6] . By supplying daily customized diets to individual animals, Indian farmers can notably decrease the environmental load and reduce feed costs (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . This is particularly relevant given India's concerns regarding nitrate pollution of aquifers and surface water eutrophication from pig manure (Koley et al., 2023; Pomar and Remus, 2019) [6,9] . www.extensionjournal.com Furthermore, the move toward low-protein, amino-acidsupplemented diets offers a path to reducing nitrogen excretion (Koley et al., 2023; Johannsen et al., 2024) [6,5] . India's tropical climate also necessitates a specialized focus on mitigating heat stress (DSM-Firmenich, 2025). Seasonal temperature spikes increase oxidative stress, making the integration of precision vitamin nutrition-specifically higher levels of Vitamins A, C, and E-essential for maintaining productivity. Additionally, given the high cost of energy, adopting advanced feed processing technologies and exogenous enzymesis critical for maximizing nutrient bioavailability from locally available feedstuffs (Rojas and Stein, 2015; Zheng et al., 2021) [11,13] . By bridging global modern concepts with the local production context, the Indian swine industry can ensure a future that is both economically profitable and environmentally responsible (Koley et al., 2023) [6] .

Conclusion

The evolution of swine nutrition toward modern, datadriven paradigms is essential to meet the complex metabolic demands of today's high-productivity genotypes. Precision pig feeding represents a breakthrough for sustainability, providing a system that delivers individualized nutrition to reduce feed costs and decrease nitrogen and phosphorus excretion by over 38%. For India, where feed represents the primary production cost (65-75%), adopting these strategies alongside low-protein, crystalline amino-acid-supplemented diets is an economic and environmental imperative to mitigate nitrate pollution and enhance industry competitiveness.

Simultaneously, the specialized management of hyper-prolific sows and the mitigation of weaning-associated intestinal disorders through functional additives are critical for maintaining animal welfare and productivity. By integrating advanced feed processing technologies to optimize particle size and precision vitamin nutrition to combat environmental stressors like heat stress, the industry can further maximize nutrient bioavailability. Ultimately, transitioning from traditional standards, such as BIS (1986), toward these global concepts will provide the Indian swine sector with a comprehensive roadmap for a sustainable, efficient, and profitable future.

References

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