Optimizing carcass yield through lysine-supplemented diets with locally sourced kepayang (Pangium edule) oil in broilers

Wiwaha Anas Sumadja, Noferdiman and Nurhayati

Department of Animal Husbandry, Faculty of Animal Science, University of Jambi, Indonesia
wiwahasumadja@unja.ac.id

Abstract

This study investigated the effects of lysine supplementation in broiler diets containing kepayang (Pangium edule) oil on growth performance and carcass traits. Two hundred day-old broiler chicks (initial BW: 48.52 g) were assigned to a completely randomized design with four dietary treatments and five replicates of 10 birds each. The treatments were: T1 = control diet (no kepayang oil or lysine), T2 = 2% kepayang oil + 0.4% lysine, T3 = 4% kepayang oil + 0.8% lysine and T4 = 6% kepayang oil + 1.2% lysine. Feed intake, body weight gain, feed conversion ratio (FCR), slaughter weight, carcass weight, abdominal fat and internal organ traits were recorded. Data were analyzed using ANOVA and significant differences were tested using Duncan's multiple range test. Lysine supplementation in diets containing kepayang oil significantly reduced feed intake during the finisher phase and overall period (p<0.05), with no significant effect during the starter phase. Body weight gain and FCR were not significantly affected across all periods. Slaughter and carcass weights were significantly improved in T3 (p<0.05), while relative carcass weight and internal organ weights showed no significant differences, except heart weight (p=0.057). These findings suggest that 4% kepayang oil combined with 0.8% lysine can enhance carcass yield without adverse effects on performance.

Keywords: carcass yield, growth performance, internal organs, Kepayang oil

Introduction

In many rural areas of developing countries, poultry farming plays a vital role in household income, nutrition and food security. However, high feed costs—particularly for energy and protein sources—remain a major constraint to productivity and profitability. Since feed can account for up to 70% of total production costs, identifying affordable and locally available feed resources is critical to improving the sustainability of smallholder poultry systems (Thirumalaisamy et al 2016).

Vegetable oils are effective energy sources in broiler diets. They improve feed palatability, support fat-soluble vitamin absorption and contribute essential fatty acids that enhance feed efficiency and energy utilization (Baião and Lara 2005; Poorghasemi et al 2015; Attia et al 2019). While palm, soybean and coconut oils are commonly used, their cost and availability can be limiting in rural communities. Exploring alternative oils derived from local plants may provide a cost-effective solution.

Kepayang (Pangium edule Reinw) is a native tree found widely in Southeast Asia, including in rural Indonesia, where its seeds are traditionally used in food after proper detoxification. Oil extracted from kepayang seeds is rich in unsaturated fatty acids, especially α-linolenic acid, which supports energy metabolism and may enhance the nutritional quality of poultry meat (Cakrawati 2006; Fauzi et al 2008). Despite its availability, kepayang oil has received little attention as a feed ingredient.

In addition to energy, amino acid balance is essential in poultry diets. Lysine, often the second limiting amino acid in corn–soybean diets, is critical for protein synthesis, muscle growth and immune function (Siqueira et al 2013). Supplementing lysine in diets containing alternative energy sources may improve overall feed utilization and growth performance.

This study investigates the combined effects of kepayang oil and lysine supplementation on growth performance and carcass traits in broilers. The goal is to assess the potential of this locally available oil as a practical and sustainable feed ingredient for rural poultry production

Materials and methods

Experimental design, birds and diets

A total of 200 unsexed day-old broiler chicks (strain CP 707) with uniform initial body weights were randomly allocated to four dietary treatments in a completely randomized design (CRD). Each treatment consisted of five replicates with ten birds per replicate. The birds were housed in floor pens under standardized management, hygienic and environmental conditions for the entire duration of the 35-day trial.

The kepayang oil used in this study was obtained from a local market in Sarolangun Regency, Jambi Province, Indonesia. The oil was traditionally produced by local communities living around the forest area, using seeds extracted from the ripe fruits of kepayang trees (Photo 1 and Photo 2). This locally sourced oil represents a typical product utilized in traditional practices and was chosen to reflect the potential of indigenous resources in poultry feed applications.

Photo 1. Kepayang (Pangium edule Reinw) Trees Source: https://trubus.id/kepayang-menjaga-alam/	Photo 2. Kepayang (Pangium edule Reinw) Fruits Source: https://gemapos.id/25581/mengenal-pohon-kepayang-si-penghasil-kluwek-dan-minyak-yang-sehat#google_vignette

The experimental diets were formulated with graded levels of kepayang (Pangium edule Reinw) oil and supplemental lysine as follows:

T1: Basal diet without kepayang oil or lysine supplementation (control),

T2: Basal diet + 2% kepayang oil + 0.4% lysine,

T3: Basal diet + 4% kepayang oil + 0.8% lysine,

T4: Basal diet + 6% kepayang oil + 1.2% lysine.

The compositition of feed ingredients in research diets and nutrients content of treatment diets are presented in Tables 1 and 2 respectively. All diets were formulated to be isoenergetic and isonitrogenous and to meet or exceed the nutrient requirements recommended by the NRC (1994) for broiler chickens. Feed and water were provided ad libitum throughout the study.

Growth performance measurement

Growth performance was evaluated across two feeding phases: the starter phase (1–21 days) and the finisher phase (22–35 days). Parameters recorded included body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR). Feed intake was calculated as the difference between the feed offered and feed refused, while FCR was computed as the ratio of feed intake to body weight gain.

Carcass evaluation

At the end of the feeding trial (day 35), two birds from each replicate (closest to the replicate's average body weight) were selected for carcass analysis. Birds were fasted for 12 hours, humanely slaughtered, defeathered and eviscerated. Carcass traits recorded included live body weight, slaughter body weiht and carcass weight. In addition, the weights of internal organs such as liver, heart and gizzard, proventriculus and pancreas were recorded and lengths of the duodenum, jejunum, ileum were measured. Abdominal fat deposition also was measured.

Statistical analysis

Data were subjected to analysis of variance (ANOVA) according to the CRD model using SAS software (Version 9.3; SAS Institute Inc., Cary, NC, USA). When significant differences (p < 0.05) were detected, treatment means were compared using Duncan’s multiple range test. All results are presented as means ± standard error of the mean (SEM).

Results and discussion

Growth performances

The effects of dietary treatments on growth performance are presented in Tables 3. During the starter period (1–21 days of age), no significant differences (p > 0.05) were observed among treatments for feed intake, body weight gain (BWG), or feed conversion ratio (FCR). These findings align with those reported by Nájera-Pedraza et al (2023), who observed no effects of palm oil supplementation on broiler performance during early growth. Similarly, Mardhotillah et al (2020) and Al-Abdullatif et al (2023) reported that the inclusion of dietary oils such as rice bran or palm oil did not influence broiler BWG in the initial three weeks. The lack of effect observed in this study may be attributed to the isonitrogenous and isoenergetic nature of the experimental diets, as well as the possibility that birds prioritize lean tissue development over fat accumulation during early growth stages. Moreover, the nutritional modifications (e.g., added lysine and kepayang oil) may not have exerted substantial influence due to adequate baseline nutrient levels in starter diets.

During the finisher period (22–35 days of age), feed intake was significantly influenced by dietary treatments ( p < 0.05). Birds fed diets with higher levels of kepayang oil and lysine consumed less feed, which could be attributed to the increased energy density of the diet or altered palatability and digestibility. Nurmi et al (2018) and Ahiwe et al 2018 emphasized that metabolizable energy levels strongly influence feed intake in broilers. The findings are also consistent with those of Prayogi (2007) and Ayed et al (2015), who reported that increasing oil inclusion levels reduced voluntary feed intake. Despite this reduction, BWG and FCR were not significantly affected (p > 0.05), suggesting that broilers were able to maintain growth and feed efficiency through more effective nutrient utilization from the energy-dense diets. However, it is important to note that FCR did not improve, indicating efficient but not enhanced nutrient assimilation.

In the overall period (1–35 days), feed intake was significantly lower ( p < 0.01) in treatments receiving higher kepayang oil and lysine levels. This reduction may reflect the improved nutrient density and utilization efficiency of the diets. Once the birds’ energy and amino acid requirements were met, feed intake naturally declined. These findings are in agreement with El-Bahr et al (2021) and Prayogi (2007), who noted a similar pattern of decreased intake in high-energy or lysine-supplemented diets. BWG and FCR remained unaffected (p> 0.05), indicating that reduced intake did not compromise growth performance. Nonetheless, the absence of improvement in FCR reinforces the interpretation that while birds consumed less, they maintained—not enhanced—growth efficiency.

The absence of significant effects on BWG, feed intake and FCR across all periods is consistent with Kiani et al (2017), who found no performance response to canola oil and lysine inclusion across different growth phases. However, it contrasts with Alcicek et al (2004), who observed performance improvements with herbal essential oils. The current findings suggest that while kepayang oil and lysine supplementation do not impair broiler performance, they may not provide additional benefits under nutritionally balanced conditions. It is also possible that interactions between high levels of dietary lipids and amino acids with other feed components may have modulated nutrient availability, minimizing their efficacy.

Carcass traits and internal organ

Carcass data (Table 4) showed that both slaughter weight and carcass weight were significantly increased (p < 0.05) in birds receiving higher levels of kepayang oil and lysine. This suggests improved growth and nutrient assimilation potentially driven by enhanced energy and amino acid availability. These findings are in agreement with Poorghasemi et al (2013), who demonstrated that mixed fat sources (tallow and vegetable oils) improved carcass yields in broilers. However, the carcass yield (relative carcass weight) was not significantly affected (p > 0.05), likely due to proportional increases in other body components such as internal organs, bone, or fat mass. This explanation aligns with Konieczka et al (2021), who reported no effect of lysine inclusion on carcass yield despite increased body weight in turkeys.

In contrast to the improved carcass traits, most internal organ parameters (lengths of the duodenum, jejunum, ileum; weights of the liver, gizzard, proventriculus and pancreas) in Table 5 were unaffected by the dietary treatments. These traits are often more closely associated with genetic factors, bird age and health status rather than dietary fat or lysine levels. However, there was a trend toward significant reduction in heart weight was observed (p = 0.057). This may suggest a localized nutrient imbalance or altered tissue distribution in response to high dietary supplementation. Excessive levels of kepayang oil and lysine may disrupt the balance of other essential nutrients, leading to reduced development of certain organs, including the heart. This highlights the need for cautious formulation to avoid oversupplying nutrients that may interfere with physiological development.

Abdominal fat deposition was not significantly affected by dietary treatments. This result may reflect a complex balance between energy intake, expenditure and metabolic regulation. Even with higher energy density in the diet, broilers may have maintained energy equilibrium, thereby preventing excess fat accumulation. Similar observations were made by Sterling et al (2006), who found no significant changes in abdominal fat with increased lysine supplementation. This outcome contrasts with findings from Crespo and Esteve-Garcia (2002) and González-Ortiz et al (2013), who noted reduced abdominal fat in birds fed diets rich in unsaturated fatty acids (e.g., linseed oil). The absence of a similar response in this study could be due to differences in the fatty acid composition of kepayang oil, which may not influence lipid metabolism to the same extent as omega-3-rich oils.

Numerous studies have explored the effects of oil types and levels on broiler performance and carcass traits. Palm oil, for instance, increases palmitic and oleic acids in muscle tissue, improving meat stability (Saminathan et al 2022), whereas oils high in erucic acid (e.g., rapeseed oil) have been associated with reduced performance (Attia et al 2020). Insect oil and essential oils from garlic or lemongrass have also shown positive effects on performance and immunity (Benzertiha et al 2019; Elbaz et al 2022). The current study contributes to this body of knowledge by demonstrating that supplementation with kepayang oil and lysine—particularly at the highest level (T3)—can enhance slaughter and carcass weights without negatively impacting feed efficiency or most physiological parameters.

Conclusion

Supplementing broiler diets with kepayang (Pangium edule Reinw) oil and graded levels of lysine affected performance outcomes and carcass characteristics. The inclusion of 6 % kepayang oil and 1.2 % lysine reduced feed intake without compromising growth or feed conversion, while the combination of 4 % kepayang oil with 0.8 % lysine (T3) was optimal for improving slaughter and carcass weights. Internal organ development and abdominal fat deposition remained unaffected, indicating no adverse effects on health parameters. These findings support the use of kepayang oil, particularly when combined with appropriate lysine levels, as a promising alternative energy and amino acid source in broiler nutrition strategies aimed at improving carcass yield without compromising performance.

Acknowledgments

The authors express their gratitude to the Faculty of Animal Science, University of Jambi, for providing facilities and funding. Special thanks are extended to the technical staff and students who assisted during the feeding trial and data collection.

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