Growth Performance, Carcass Characteristics and Meat Quality of Grower Native Chicken (Gallus gallus domesticus L.) fed with Superworm (Zophobas morio F.) as Protein Source Substitute to Soybean Meal (Glycine max L.)

Anthony G Magsalay, Chelie L Carnoso and Richelle A Niepes*

College of Agriculture, Forestry and Environmental Sciences, Mindanao State University at Naawan, Naawan, Misamis Oriental, Philippines 9023
* richelle.niepes@msunaawan.edu.ph

Abstract

Insects have gained attention as alternative protein sources in broiler chicken diets, but their potential for native chickens remains understudied. This research investigated the effects of substituting Superworm ( Zophobas morio) as a protein source for Soybean meal (Glycine max) in the diets of grower native chickens (Gallus gallus domesticus). The study evaluated growth performance, carcass characteristics, and meat quality parameters. Forty-eight 6-week-old grower native chickens were divided into four treatment groups: T1 (control), T2, T3, and T4, with varying proportions of Superworm and Soybean meal. The results showed that feed intake was highest in T1 (5% Superworm, 10% Soybean meal) and lowest in the control group. Treatment T2 (10% Superworm, 5% Soybean meal) exhibited the highest body weight gain, and T2 and T3 (15% Superworm, 0% Soybean meal) showed the best feed conversion ratio. Carcass characteristics indicated no significant differences (p>0.05) in carcass weight and dressing percentage among the treatments. Meat quality analysis revealed improved water holding capacity and sensory attributes (juiciness, aroma, tenderness, and overall liking) in Superworm-based diets, particularly in T3. These findings suggest that Superworm can be a potential alternative protein source in poultry feed, enhancing growth performance and improving meat quality in grower native chickens.

Keywords: alternative protein source, carcass yield, insect meal, native chicken, sensory attributes

Introduction

In the Philippines, the native chicken industry has a special place in both rural and urban households (DOA 2021). Revered for its unique taste, distinctive flavor, and texture, as well as its lower fat content, the native chicken, or Gallus gallus domesticus, is a beloved poultry choice among Filipinos (Peralta et al 2020). Additionally, native chicken meat and eggs are considered healthier due to their lower cholesterol content (DOA 2021). For farmers, raising these chickens is more than just a cultural tradition; it is an opportunity for supplementary income. Despite the slower growth rate compared to commercial poultry, native chickens remain a popular choice due to their culinary advantages (Cabarles 2013). Moreover, the government recognizes the industry's significant economic contribution, extending resources and attention to improve the native chicken farming sector.

The diet of native chickens is crucial to their growth and meat quality, with protein being a pivotal nutritional component. In commercial poultry farming, protein is a paramount ingredient that significantly influences the growth performance, quality of meat production. Soybean meal, in particular, has long been the go-to protein source for farm animals. It represents a large portion of global protein feedstuff output and has a feeding value that surpasses any other plant protein source. makes it inaccessible for local farmers, and the unavailability of soybeans in the Philippines further complicates its usage. As a result, there is a pressing need to find an affordable, high-quality, and locally available substitute. This leads to the utilization of insect diets such darkling beetles, commonly known as superworms ( Zophobas morio F.). These insect larvae, often reaching lengths of 2 inches, are an excellent source of protein for several types of birds, including chickens.

Studies have shown that insects can be effective alternative protein sources in the diets of broiler chickens, impacting growth performance, meat quality and carcass yield yield (Murawska et al 2021; Benzertiha et al 2020; Kieronczyk et al 2023). However, most studies have focused on the impact of insects on broiler chickens and have overlooked their potential for native chickens. In the case of native chickens, their nutritional requirements are often overlooked, resulting in slower growth rates. Therefore, this study aims to evaluate the effect of gradual substitution (5-15% Superworm) to the growth performance, carcass characteristics and meat quality of the grower Native Chicken.

Materials and methods

The study strictly adhered to the animal welfare guidelines. Forty-eight (48) heads of 6-week-old grower phase Basilan strain native chicken (Gallus gallus domesticus) utilized in the study. The birds housed into four treatments, each replicated four times with three chickens per replicate. The experiment was laid out in a completely randomized design. The experimental treatments were: Treatment 1 (T1) served as the control group, where the feed consisted solely of 15% Soybean meal (SBM). Treatment 2 (T2) was comprised of 5% Fresh Super Worm (FSW) and 10% SBM. Treatment 3 (T3) included 10% FSW and 5% SBM, while Treatment 4 (T4) consisted of 15% FSW. The experimental treatments formulation was presented in Table 2. The chickens were reared in wire cages measuring 2×1×0.5 m.

The Superworms ( Zophobas morio F.) were purchased at the College of Agriculture in MSU-Main Marawi City. A stock culture of newly emerged Z. morio adults was allowed to mate and oviposit their eggs on corrugated cardboard strips. The newly hatched Superworms (Zophobas morioF.) were reared in a secured container with sufficient height to prevent escape. The container covers were equipped with drilled holes on the top to prevent mold growth. Vegetable scraps were provided as substrate, and the substrates were changed every 2-3 days when signs of mold appeared. Once the Superworms transformed into larvae, they were used as live feedstuff to feed the six-week-old Basilan chickens in different treatment groups. Superworms were subjected to proximate analysis to determine its nutrient composition (see Table 1).

Fresh Superworms were utilized to replicate the practices of native chicken growers and free-range systems, where insects are typically served fresh rather than processed into powder or meal. This approach aimed to emulate the real-life conditions and practices of these traditional systems while minimizing the economic expenses associated with the processing of Superworms into powder or meal. By using fresh Superworms directly, the study sought to mirror the natural feeding habits of native chickens and ensure that the results would be applicable and relevant to native chicken production in a cost-effective manner. The native chickens were fed twice daily, at 6:00 am-7:00 am and 3:00 pm-4:00 pm. To prevent dehydration, they were provided with an ample supply of water ad libitum. During feeding, the feeders and waterers were thoroughly cleaned with soap and water before adding a new set of feeds to ensure no contamination in the feed material. The feeding trial lasted for 4 weeks (6 ^th to 10 ^th week age of native chicken).

Data on growth performance such as feed intake, body weight gain and FCR were collected. At the end of the 4th week of the feeding trial, forty-eight (48) native chickens were slaughtered to assess the carcass characteristics and meat quality. Chickens were individually slaughtered following standard procedures to ensure humane handling and minimize stress.

Dressing percentage is a measure of the proportion of the live weight of the animal that is retained as the dressed carcass weight after the removal of non-edible parts during the slaughter process. It indicates the efficiency of the dressing process and can vary depending on factors such as breed, age, and management practices.

To calculate the dressing percentage, the dressed carcass weight is divided by the live weight of the animal and multiplied by 100.

Meat cut-up weights and organ weights refer to the weights of specific meat cuts obtained from the carcass, such as breast, thighs, wings, backbone, neck, feet, head, proventriculus, gizzard, liver, spleen, pancreas, heart, small intestine and large intestine and were measured using a digital weighing scale. Meat cut-up yield and organ yield represents the proportion of meat/organ obtained from a specific part of the carcass in relation to its initial weight. It provides information on the efficiency of utilizing meat/organ from different portions of the animal.

To calculate the yield, the weight of a specific cut/organ is divided by the initial weight of the carcass and multiplied by 100.

The native chicken breast meat samples were obtained from the right pectoralis muscle and were analyzed after the post-slaughter period. The pH values of the breast meat samples were measured to assess their acidity levels at two time points: 45 minutes post-mortem, known as the initial pH level, and at 24 hours post-mortem. Prior to pH measurement, the skin was carefully removed to expose the breast meat. An incision was made in the right breast meat portion to create an opening gap between the muscles, allowing for the insertion of a pH probe to determine the pH value.

Water holding capacity (WHC) refers to the ability of meat or muscle tissue to retain water within its structure. A total of five grams of minced meat were weighed, and eight milliliters of a 0.6 ml NaCl solution were added to a 13-milliliter centrifuge tube. After centrifugation, the supernatant's volume was measured with a 10 ml volumetric graduated cylindrical container, and the findings were expressed as the fluid the sample had kept using the formula given below.

In the sensory quality procedure, specific cuts of native chicken meat from the breast area were boiled without spices or seasonings for 30 minutes to ensure proper cooking. The cooked samples were sliced into bite-sized cuts for evaluation. A panel of 20 trained individuals was selected based on health criteria and sensory perception ability. Each meat sample was coded with random alphanumeric labels to prevent bias during evaluation. The panelists assessed the sensory attributes using a 5-point hedonic scale, independently rating taste, juiciness, aroma, tenderness, and overall liking without prior knowledge of the sample's characteristics. The scale ranged from 1 (dislike very much) to 5 (like very much).

The gathered data were subjected to one-way analysis of variance (ANOVA) and analyzed using SPSS software. Differences among treatments were determined by performing Tukey's post-hoc test. A significance level of p<0.05 was considered to indicate statistical significance.

Results and discussion

Growth performance

The higher feed intake observed in the treatment groups with increasing levels of Superworm inclusion can be attributed to the nutritional composition of Superworms compared to the control group (see Table 3). Superworms are rich in protein, essential amino acids, and other important nutrients, which can stimulate feed intake in poultry. One study by Dragojlovic et al., in 2022 investigated the nutritional composition of Superworms (Zophobas morio) and found that they contain high levels of crude protein, essential amino acids, and energy. The researchers reported that Superworms have a crude protein content of approximately 20-40%, making them a valuable protein source for animal feed. Amino acids contribute to enhancing feed palatability through various mechanisms, ultimately making the feed more appealing to poultry. One-way amino acids enhance palatability is through taste perception. Certain amino acids, such as glutamic acid and aspartic acid, contribute to the savory or umami taste sensation. These amino acids can enhance the overall taste profile of the feed, making it more enjoyable for poultry to consume (Alagawany et al 2020). Furthermore, amino acids are involved in the production of neurotransmitters in the brain. Neurotransmitters regulate appetite, feeding behavior, and food intake. By providing an adequate supply of essential amino acids, the production of neurotransmitters involved in appetite stimulation can be enhanced, resulting in increased feed intake (Dodd et al 2015).

Moreover, based on present study, it can be inferred that varying levels of fresh Superworm as a protein substitute to Soybean meal (SBM) in the diet of grower native chickens had no significant effect on their body weight gain (BWG), and feed conversion ratio (FCR). It can be observed that the FCR in the present study is high 10.20 to 12.30 which is slightly higher on the normal FCR values of native chicken. Genetic selection plays a crucial role, as broilers have been selectively bred for traits that promote rapid growth and efficient feed utilization. This genetic advantage, combined with their faster growth rate, higher metabolic rate, increased appetite, and specific muscle composition, enables broilers to convert feed into body weight more efficiently. Native chickens, on the other hand, have not undergone extensive breeding for such traits, resulting in a comparatively higher FCR. Native chickens under backyard production system reported FCR to be higher (Mapiye et al 2008).

Another factor is that the chickens were still at the early stages of growth (6-10 weeks) by which the growth performance was not properly exhibited. Younger chickens, especially during their early growth stages, might have a higher FCR as they are still developing and not yet at their peak growth performance. This is because young chickens expend more of their energy for maintenance and development rather than weight gain.

While the growth parameters (FI, BWG, FCR) were not significantly affected by the proportion of FSW in the diets, it is also important to consider potential effects on meat quality, immune response, and overall health of the chickens. Some studies have shown that the inclusion of insect meal in poultry diets can positively affect meat quality attributes, such as the fatty acid profile and oxidative stability (Biasato et al 2018), while others have suggested a potential improvement in immune response (Altmann et al 2018).

Carcass characteristics

The table 4 presents the results of a study examining the carcass characteristics of grower native chickens (Gallus gallus domesticus) from 6 to 10 weeks of feeding trial, specifically when fed with varying levels of fresh Superworm (Zophobas morio) as a protein substitute to Soybean meal (Glycine max).

The mean carcass weights and dressing percentages showed a general increase when fresh superworm meal was used to replace soybean meal. The protein content of superworms is reported to be between 42-54% of dry matter, making them a robust source of protein (Finke 2002). Protein is a vital macronutrient needed for muscle development and growth in poultry, thus a high-protein diet could result in heavier carcass weights. Additionally, superworms are rich in other essential nutrients, including certain amino acids, fatty acids, vitamins, and minerals (Finke 2002). These nutrients are crucial for the overall health and growth of chickens, which could also contribute to increased carcass weight and dressing percentage.

In the recent study, it is noticeable that treatment T3, where chickens were fed with a diet consisting of 15% Superworm and 0% Soybean meal, generally resulted in higher meat cut weights. This observation is in line with several studies that have explored the use of insect-based protein sources in poultry diets. For example, Biasato et al 2018 found comparable growth performance and carcass traits in broiler chickens fed with mealworm meal and those fed traditional soybean meal. Furthermore, Marco et al (2015) showed that broiler chickens fed diets with Tenebrio molitor larvae exhibited no significant differences in growth performance or carcass traits compared to chickens fed conventional diets.

It can be observed that the small intestine weight and yield was improved at T2, where chickens were fed with a diet consisting of 10% Superworm and 5% Soybean meal. The mechanism by which insect meal, such as Superworm (Zophobas morio), increases small intestine weight and yield in animals like chickens is not yet fully elucidated, and ongoing research aims to better understand this phenomenon. However, several potential factors could contribute to the observed effects. Firstly, insect meals, including Superworms, are highly nutritious and rich sources of high-quality protein. When animals are fed insect-based diets, they receive a concentrated source of essential amino acids, which serve as the building blocks of proteins. This increased protein content in the diet may stimulate intestinal cell proliferation and the growth of the intestinal lining, leading to an increase in small intestine weight and yield (Colombino et al., 2021)

Meat quality

The inclusion of fresh Superworm at higher levels led to higher pH levels in breast meat (see Table 5). This finding in the present study is consistent with a study by Elahi et al 2022 on broiler chickens fed with insect meal, where they observed that higher inclusion levels of insect meal resulted in elevated pH levels of breast meat. The inclusion of fresh Superworm, particularly at the highest level, resulted in lower pH levels in breast. The improved water holding capacity (WHC) observed in the breast meat of chickens with Superworm inclusion can be attributed to several factors. Insect-based proteins, like those found in Superworm, have been reported to possess a higher water-binding capacity owing to their unique protein structure and composition (Pan et al 2022). The presence of high levels of soluble proteins and chitin in Superworm may have contributed to the enhanced water-holding properties in the breast meat. This increased WHC in the meat could have a direct impact on the sensory attributes, such as juiciness and tenderness, making the meat more succulent and desirable to consumers. Additionally, the higher WHC could also contribute to the improved overall liking of the meat as it enhances the eating experience and contributes to greater consumer satisfaction. Thus, the relationship between improved water holding capacity and sensory attributes highlights the potential of Superworm as a valuable protein source in poultry feed, leading to enhanced meat quality and palatability.

Conclusion

The research demonstrates that incorporating Superworm (Zophobas morio) as a protein substitute in the diet of grower native chickens has the potential to positively influence their growth performance and meat quality. Among the different treatments, Treatment T2, which included 10% Superworm and 5% Soybean meal, showed the highest body weight gain and the best feed conversion efficiency. Superworm-based diets also improved water holding capacity and sensory attributes such as juiciness, aroma, tenderness, and overall liking of the meat, with Treatment T3, consisting of 15% Superworm and 0% Soybean meal, receiving the highest scores in these attributes.

References

Alagawany M, Elnesr S S, Farag M R, Tiwari R, Yatoo M I, Karthik K , Michalak I and Dhama K 2020 Nutritional significance of amino acids, vitamins and minerals as nutraceuticals in poultry production and health - a comprehensive review. The veterinary quarterly, 41(1), 1-29. https://doi.org/10.1080/01652176.2020.1857887

Altmann B A, Neumann C, Velten S, Liebert F and Mörlein D 2018 Meat Quality Derived from High Inclusion of a Micro-Alga or Insect Meal as an Alternative Protein Source in Poultry Diets: A Pilot Study. Foods (Basel, Switzerland) , 7(3), 34. https://doi.org/10.3390/foods7030034

Benzertiha A, Kieronczyk B, Kolodziejski P, Pruszynska-Oszmalek E, Rawski M, Józefiak D and Józefiak A 2020 Tenebrio molitor and Zophobas morio full-fat meals as functional feed additives affect broiler chickens' growth performance and immune system traits. Poultry science, 99(1), 196-206. https://doi.org/10.3382/ps/pez450

Biasato I, Gasco L, De Marco M, Renna M, Rotolo L, Dabbou S, Capucchio M T, Biasibetti E, Tarantola M, Sterpone L, Cavallarin L, Gai F, Pozzo L, Bergagna S, Dezzutto D, Zoccarato I and Schiavone A 2018 Yellow mealworm larvae (Tenebrio molitor) inclusion in diets for male broiler chickens: effects on growth performance, gut morphology, and histological findings. Poultry science, 97(2), 540-548. https://doi.org/10.3382/ps/pex308

Cabarles J C 2013. Production potentials of native chickens (Gallus gallus domesticus L.) of Western Visayas, Philippines. Tropical animal health and production , 45(2), 405-410. https://doi.org/10.1007/s11250-012-0230-1

Colombino E, Biasato I, Ferrocino I, Bellezza Oddon S, Caimi C, Gariglio M, Dabbou S, Caramori M, Battisti E, Zanet S, Ferroglio E, Cocolin L, Gasco L, Schiavone A and Capucchio M T 2021 Effect of Insect Live Larvae as Environmental Enrichment on Poultry Gut Health: Gut Mucin Composition, Microbiota and Local Immune Response Evaluation. Animals : an open access journal from MDPI, 11 (10), 2819. https://doi.org/10.3390/ani11102819

DOA (Department of Agriculture) 2021 Native Chicken Industry Roadmap 2020-2030. Retrieved from https://www.da.gov.ph/wp-content/uploads/2021/05/WEB-NATIVE-CHICKEN-ROADMAP.pdf

Dodd G T, Decherf S, Loh K, Simonds S E, Wiede F, Balland E, Merry T L, Münzberg H, Zhang Z Y , Kahn B B, Neel B G, Bence K K, Andrews Z B, Cowley M A and Tiganis T 2015 Leptin and insulin act on POMC neurons to promote the browning of white fat. Cell, 160(1-2), 88-104. https://doi.org/10.1016/j.cell.2014.12.022

Dragojlovic D, Ðuragic O, Pezo L, Popovic L, Rakita S, Tomicic Z and Spasevski N 2022 Comparison of Nutritional Profiles of Super Worm (Zophobas morio) and Yellow Mealworm (Tenebrio molitor) as Alternative Feeds Used in Animal Husbandry: Is Super Worm Superior?. Animals : an open access journal from MDPI , 12(10), 1277. https://doi.org/10.3390/ani12101277

Elahi U, Xu C C, Wang J, Lin J, Wu S G, Zhang H J and Qi G H 2022 Insect meal as a feed ingredient for poultry. Animal bioscience, 35(2), 332-346. https://doi.org/10.5713/ab.21.0435

Finke M D 2002 Complete nutrient composition of commercially raised invertebrates used as food for insectivores. Zoo Biology, 21 , 269-285. DOI: 10.1002/ZOO.10031

Kieronczyk B, Rawski M, Mikolajczak Z, Szymkowiak P, Stuper-Szablewska K and Józefiak D 2023 Black Soldier Fly Larva Fat in Broiler Chicken Diets Affects Breast Meat Quality. Animals : an open access journal from MDPI, 13(7), 1137. https://doi.org/10.3390/ani13071137

Kongsup P, Lertjirakul S, Chotimanothum B, Chundang P and Kovitvadhi A 2022 Effects of eri silkworm (Samia ricini) pupae inclusion in broiler diets on growth performances, health, carcass characteristics and meat quality. Animal bioscience, 35(5), 711-720. https://doi.org/10.5713/ab.21.0323

Mapiye C, Mwale M, Mupangwa J F, Chimonyo M, Foti R and Mutenje MJ 2008 A research review of village chicken production constraints and opportunities in Zimbabwe. Asian-Australasian Journal of Animal Sciences 2008;21(11): 1680-1688. DOI: https://doi.org/10.5713/ajas.2008.r.07

Marco M D, Martínez S, Hernández F, Madrid J, Gai F, Rotolo L, Belforti M, Bergero D, Katz H, Dabbou S, Kovitvadhi A, Zoccarato I, Gasco L and Schiavone A 2015 Nutritional value of two insect larval meals (Tenebrio molitor and Hermetia illucens) for broiler chickens: Apparent nutrient digestibility, apparent ileal amino acid digestibility and apparent metabolizable energy. Animal Feed Science and Technology, 209 , 211-218. DOI: 10.1016/J.ANIFEEDSCI.2015.08.006

Murawska D, Daszkiewicz T, Sobotka W, Gesek M, Witkowska D, Matusevicius P and Bakula T 2021 Partial and Total Replacement of Soybean Meal with Full-Fat Black Soldier Fly (Hermetia illucens L.) Larvae Meal in Broiler Chicken Diets: Impact on Growth Performance, Carcass Quality and Meat Quality. Animals, 11(9), 2715. MDPI AG. Retrieved from http://dx.doi.org/10.3390/ani11092715

Pan J, Xu H, Cheng Y, Mintah B K, Dabbour M, Yang F, Chen W, Zhan Z, Dai C, He R and Ma H 2022 Recent Insight on Edible Insect Protein: Extraction, Functional Properties, Allergenicity, Bioactivity, and Applications. Foods (Basel, Switzerland) , 11(19), 2931. https://doi.org/10.3390/foods11192931

Schiavone A, De Marco M, Martínez S, Dabbou S, Renna M, Madrid J, Hernandez F, Rotolo L, Costa P, Gai F and Gasco L 2017 Nutritional value of a partially defatted and a highly defatted black soldier fly larvae ( Hermetia illucens L.) meal for broiler chickens: apparent nutrient digestibility, apparent metabolizable energy and apparent ileal amino acid digestibility. Journal of animal science and biotechnology , 8, 51. https://doi.org/10.1186/s40104-017-0181-5