INTRODUCTION

Dietary energy is a fundamental and economically important component of broiler feed formulation because of its substantial influence on production costs, growth performance, feed efficiency, and carcass quality. Energy is typically the most expensive nutrient in poultry diets and often accounts for the largest proportion of feed-related expenditures [1]. Optimizing dietary energy levels can improve profitability by enhancing feed conversion ratio (FCR) and growth rate while reducing feed intake (FI) and associated production costs. Furthermore, precise energy formulation may reduce environmental impacts through lower nitrogen excretion, thereby supporting sustainable poultry production systems [2]. Reducing dietary energy while supplementing diets with emulsifiers has emerged as an effective nutritional strategy to maintain or improve growth performance, nutrient digestibility, and feed efficiency while lowering feed costs. Emulsifiers, including lecithin-based and synthetic compounds, improve fat emulsification and absorption, thereby compensating for the lower energy density of reduced-energy diets [3]. Feed emulsifiers function by reducing the size of dietary fat globules, increasing their surface area for enzymatic hydrolysis by intestinal lipase, and promoting micelle formation, which facilitates lipid transport across the intestinal epithelium. Consequently, emulsifiers improve fat utilization and enhance the absorption of fat-soluble vitamins [4].

Numerous studies have demonstrated that emulsifier supplementation can improve growth performance, nutrient digestibility, and feed efficiency in broilers and laying hens fed energy-restricted diets [5, 6]. Enhanced ileal digestibility of crude fat, dry matter, and energy, together with increased apparent metabolizable energy (AME), further demonstrates the beneficial effects of emulsifiers on nutrient utilization [4]. In addition, emulsifiers may modulate lipid metabolism by reducing serum cholesterol and triglyceride concentrations and regulating the expression of genes associated with lipid utilization [7, 8]. Although improvements in carcass traits have been inconsistent, with only minor effects reported on dressing percentage, liver weight, and breast muscle characteristics, the principal benefits of emulsifier supplementation are associated with enhanced growth and metabolic efficiency rather than changes in carcass composition [5, 6]. These findings highlight the potential of emulsifiers to support sustainable poultry production by improving nutrient utilization and reducing feed costs. However, their biological efficacy and economic value depend on several factors, including emulsifier type, composition, dietary energy level, and feeding strategy.

The efficacy of feed emulsifiers in broiler nutrition is influenced by their chemical characteristics and mode of application. Lecithin, a naturally derived emulsifier obtained primarily from plant sources, has been widely recognized for its role in enhancing lipid metabolism, reducing serum cholesterol concentrations, and improving intestinal morphology, all of which contribute to improved nutrient absorption and physiological health in broilers [9]. Furthermore, lecithin supplementation has been associated with a reduced incidence of fatty liver hemorrhagic syndrome in laying hens, indicating broader physiological benefits. In contrast, synthetic emulsifiers have shown particular effectiveness in reduced-energy diets, where they improve fat digestibility, body weight gain, and FCR [10]. Moreover, combinations of synthetic emulsifiers with monoglycerides and lysolecithin have been reported to improve litter quality and welfare indicators, including footpad condition [11–13]. Comparative studies suggest that although synthetic emulsifiers may provide greater improvements in growth efficiency, lecithin-based emulsifiers may offer additional physiological benefits, including improved gut morphology and plasma lipid profiles [14]. Therefore, the selection of an appropriate emulsifier should align with specific production objectives, as lecithin-based products primarily support physiological health, whereas synthetic emulsifiers may be more effective at enhancing productive performance under suboptimal dietary energy conditions.

Dietary emulsifier supplementation has also been reported to influence carcass yield and fat deposition in broilers, although the magnitude of these responses depends on the type of emulsifier, dietary fat source, and dietary energy concentration. By enhancing lipid digestion and absorption, emulsifiers may improve nutrient availability for tissue accretion, thereby influencing carcass characteristics. The present study evaluated a ternary emulsifier blend composed of sorbitan esters, lysolecithin, and de-oiled lecithin. Sorbitan esters are non-ionic surfactants derived from sorbitol and fatty acids that facilitate dietary fat emulsification, thereby improving lipase accessibility and micelle formation within the gastrointestinal tract [15]. Lysolecithin, a hydrolyzed derivative of lecithin rich in lysophospholipids such as lysophosphatidylcholine, possesses superior emulsifying properties and has been associated with improved intestinal morphology, increased villus height, enhanced nutrient transport, and improved absorption of fat-soluble vitamins [16]. In addition, lysolecithin contributes to gut health and membrane permeability. De-oiled lecithin, a concentrated phospholipid fraction with reduced oil content, provides moderate emulsification capacity while improving lipid dispersion, nutrient digestibility, and feed efficiency. It also offers technological advantages, including improved heat stability and ease of feed manufacturing [17]. Collectively, these emulsifying agents may enhance lipid utilization, improve growth performance, and support carcass development in broilers fed reduced-energy diets.

Previous studies have primarily focused on single-component emulsifiers or binary emulsifier combinations, particularly lecithin, lysolecithin, and synthetic emulsifiers, administered at fixed inclusion rates throughout the production cycle [10–14]. Although these studies have demonstrated improvements in fat digestibility and growth performance, limited information is available on the efficacy of ternary emulsifier systems combining sorbitan esters, lysolecithin, and de-oiled lecithin. Furthermore, little attention has been paid to phase-specific supplementation strategies that adjust emulsifier inclusion levels in line with the physiological development of broilers. Young broilers exhibit limited endogenous bile secretion and lípid-digestion capacity, whereas digestive efficiency progressively improves with age. Therefore, a constant level of emulsifier inclusion throughout the entire production cycle may not be the most biologically efficient or economically optimal feeding strategy. In addition, data regarding the effects of ternary emulsifier blends on nutrient utilization, gastrointestinal function, and carcass characteristics in broilers fed reduced-energy diets remain scarce. Consequently, there is a need to evaluate whether a phase-specific supplementation approach can maximize the benefits of emulsifier supplementation while improving cost-effectiveness under practical commercial production conditions.

Therefore, this study was conducted to evaluate the effects of a ternary emulsifier blend comprising sorbitan esters, lysolecithin, and de-oiled lecithin on growth performance, nutrient utilization, gastrointestinal retention time, and carcass characteristics in broilers fed reduced-energy diets. In addition, the study investigated a phase-specific supplementation strategy in which higher emulsifier inclusion levels were provided during the starter and grower phases and reduced during the finisher phase. The objective was to determine whether this adaptive feeding approach could partially compensate for reduced dietary energy, improve nutrient utilization efficiency, and maintain productive performance while offering a practical and economically sustainable strategy for commercial broiler production.