Research Article

Local Maluku Feed Supplemented with Tenebrio molitor Meal Improves Metabolic Status and Reproductive Performance in Sows

Marchie Astrid da Costa1,2, Zuprizal Zuprizal3, Herdis Herdis2, Santoso Santoso2, Procula Rudlof Matitaputty2, Pradita Iustitia Sitaresmi2, Dio Fico Felsidan Diatmono1, Fransisca Gani Padmawati1, Ririn Novita4, Diah Tri Widayati1*

1Department of Animal Breeding and Reproduction, Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia; 2Research Center for Animal Husbandry, National Research and Innovation Agency, Cibinong Science Center, West Java 16915, Indonesia; 3Department of Animal Nutrition and Feed Science, Faculty of Animal Science, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia; 4Department of Animal Husbandry, Faculty of Agriculture, Musi Rawas University, Lubuklinggau, South Sumatera 31661, Indonesia.

Received | February 08, 2026; Accepted | February 28, 2026; Published | March 31, 2026

*Correspondence | Diah Tri Widayati, Department of Animal Breeding and Reproduction, Faculty of Animal Science, Fauna Street No. 3, UGM Campus Bulaksumur, Caturtunggal, Depok, Sleman 55281, Yogyakarta, Indonesia; Email: [email protected]

Citation | Costa MA, Zuprizal Z, Herdis H, Santoso S, Matitaputty PR, Sitaresmi PI, Diatmono DFF, Padmawati FG, Novita R, Widayati DT (2026). Local maluku feed supplemented with Tenebrio molitor meal improves metabolic status and reproductive performance in sows. Adv. Anim. Vet. Sci., 14(4):758-767.

DOI | https://dx.doi.org/10.17582/journal.aavs/2026/14.4.758.767

ISSN (Online) | 2307-8316

Copyright: 2026 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

INTRODUCTION

Reproductive performance of sows (Sus scrofa domesticus) determines both productivity and sustainability of pig farming enterprises (Chidgey et al., 2015). Reproductive success depends not only on conception rates (CR) and litter size, but also on physiological readiness during the mating period. During this phase, the hypothalamic–pituitary–ovarian (HPO) axis regulates follicular development, gonadotropin secretion, and estrus expression (Koketsu et al, 2017; Costermans et al., 2020). Pre–mating nutrition maintains metabolic and endocrine balance essential for folliculogenesis and steroidogenesis, including gonadotropin regulation, follicle–stimulating hormone (FSH), and estradiol (Christian and Moenter, 2010). Conversely, nutritional imbalances has been associated with altered ovarian function, shorten estrus duration, prolonged or irregular estrous cycles, reduce ovulation, and pregnancy rates (Knox, 2023).

Blood metabolite profiles provide objective indicators of physiological responses to pre–mating nutrition, reflecting metabolic efficiency and reproductive readiness (Kumala et al., 2022). Total protein reflects overall nutritional and metabolic status, directly influencing hormone synthesis and reproductive tissue function (da Costa et al., 2019). Glucose is an indicator of energy balance relevant to HPO axis activity, while cholesterol and triglycerides serve as energy substrates and steroid hormone precursors (Mahardika et al., 2023; Diatmono et al., 2024). Blood urea nitrogen (BUN) serves as a key indicator of dietary protein utilization efficiency. While physiological BUN levels reflect optimal protein metabolism tailored to reproductive requirements, excessive concentrations indicate nutritional imbalance and may impair fertility (Sitaresmi et al., 2023).

Pre–mating nutrition directly modulates reproductive hormones. FSH stimulates follicular growth, granulosa cell proliferation, and ovulation preparation (Knox, 2023). Adequate energy and protein availability, reflected by balanced blood profiles, enhances FSH secretion and estradiol synthesis (Zhang et al., 2025). Elevated estradiol extends estrus duration and intensifies behavioral expression (Christian and Moenter, 2010). Estrus duration and estrous cycle length serve as sensitive functional indicators responsive to nutritional and hormonal status. Short estrus or irregular cycles are indicative of ovarian dysfunction resulting from energy or protein deficiencies (Langendijk, 2021).

In Maluku, an archipelago in eastern Indonesia, commercial feed dependence constrains smallholder pig production through high costs, limited distribution, and price volatility. Local carbohydrate sources and fishery by–products offer potential but contain insufficient protein and essential amino acids for reproduction. Based on these considerations, it is necessary to incorporate protein–rich feed ingredients such as Tenebrio molitor (mealworm), which can optimize the digestibility of dry matter (DM) and crude protein (CP) while maintaining stable BUN levels (Jin et al., 2016). Tenebrio molitor meal has been investigated as an alternative protein source in livestock nutrition and is characterized by high CP and lipid content. Furthermore, on a DM basis, Tenebrio molitor contains approximately 44% CP, 38% crude fat, 11% fiber, 22% chitin, 3% crude ash, and 2% nitrogen–free extract (NFE), suggesting potential application in reproductive feeding strategies (Toviho and Bársony, 2022).

Integrating Tenebrio molitor meal with indigenous Maluku feedstocks offers a strategic approach to enhancing the nutritional profile and cost–effectiveness of pre–mating diets within smallholder production systems. While the supplementation of Tenebrio molitor has gained significant research interest, existing studies such as those by Jin et al. (2016) and Zacharis et al. (2024) have primarily focused on the growth performance, average daily gain (ADG), and blood metabolite status of weaning pigs. Consequently, the physiological impact of Tenebrio molitor supplementation in local Maluku diets, specifically regarding hormonal status and estrus characteristics, remains uncharacterized. Previous evidence from Jin et al. (2016) indicates that a 6% inclusion (the highest supplementation level) of Tenebrio molitor yields optimal performance in weaning pigs, suggesting that higher inclusion rates may further enhance physiological outcomes for sows. This study examined the physiological responses to 7% Tenebrio molitor supplementation, providing a scientific foundation for sustainable pig production through the utilization of local resources in tropical archipelagic environments.

MATERIALS AND METHODS

Experimental animals and procedures

The study was conducted at a community farm in Suli Village, Central Maluku Regency. Forty–five Dutch Landrace sows, all primiparous, older than one year, and with a body condition score (BCS) between 2.0 and 3.0 based on a scale of 1 to 5 (Soni et al., 2019). BCS assessments were performed by three independent observers, with the final score for each sow calculated as the mean of these observations. The sows were then randomly assigned to one of three dietary treatment groups (n=15 per group), ensuring that the initial mean BCS across all groups showed no significant differences: T0 (BCS 2.56±0.09), consisting of the traditional feed provided by local farmers; T1 (BCS 2.40±0.10), representing a conventional feed formulated according to industry standards and common farming practices; and T2 (BCS 2.48±0.09), a local Maluku feed supplemented with 7% Tenebrio molitor meal. Dietary nutrient compositions, blood metabolites, and reproductive hormone profiles were analyzed at the Laboratory of Tropical Animal Research Center (TARC), Faculty of Animal Science, Universitas Gadjah Mada. The ingredient composition for each treatment is presented in Table 1, while the corresponding nutrient compositions are detailed in Table 2.

 

Table 1: Feed formulation and ingredient proportions for sows by dietary treatment.

Feed composition	Feeding treatment
	T0 (%)	T1 (%)	T2 (%)
Tofu by product	60.00	-	-
Household waste*	25.00	-	-
Fruit (papaya)	15.00	-	-
Commercial concentrate**	-	15.00	-
Cornstarch	-	25.00	36.00
Bran	-	60.00	16.00
Sago***	-	-	29.00
Fish meal***	-	-	10.00
Tenebrio molitor meal	-	-	7.00
Mineral mix	-	-	2.00

 

*, household waste component comprised leftover cooked rice, vegetable trimmings, and fish processing by–products; **, Commercial concentrate consists of soybean meal (SBM), palm kernel cake (PKC), meat bone meal (MBM), and copra meal; ***, indicating local Maluku feed ingredients; T0, traditional feed provided by local farmers; T1, conventional feed formulated according to industry standards and common farming practices; and T2, local Maluku feed supplemented with 7% Tenebrio molitor meal.

 

Table 2: Nutrient composition of daily diets for sows across experimental treatment groups.

Daily feed nutrients	Feeding treatment
	T0 (n=15)	T1 (n=15)	T2 (n=15)
Crude protein (%)	10.52	13.65	16.43
Extract ether (%)	5.16	4.30	5.19
Crude fiber (%)	16.45	13.40	10.03
Ash (%)	5.23	12.50	7.09
Calcium (%)	0.32	0.60	0.91
Phosphor (%)	0.17	0.30	0.60
Metabolic energy (kcal/kg)	2,424.25	2,690.00	2,822.82

 

n, number of sows per group; T0, traditional feed provided by local farmers; T1, conventional feed formulated according to industry standards and common farming practices; and T2, local Maluku feed supplemented with 7% Tenebrio molitor meal.

 

Feeding and estrus synchronization protocol

The experimental diets were provided twice daily at 07:30 and 15:00, with a total feed allowance of 2.5 kg per head per day, and ad libitum access to clean drinking water throughout the study. Sows underwent a 7–day adaptation period before treatment to allow for acclimatization to the housing conditions and feeding regimen, baseline measurements included, BCS and general clinical health. The 15–day pre– and post–estrus feeding period is thought to maximize reproductive readiness via enhanced energy and protein intake. Estrous synchronization was performed by administering two intramuscular injections of 2 mL prostaglandin F2alpha (PGF2α) on days 3 and 15 of the dietary treatment period. This 12–day interval was implemented because the porcine corpus luteum (CL) is highly resistant to PGF2α–induced luteolysis before day 12 of the estrous cycle (de Rensis et al., 2012). The PGF2α utilized in this study was Lutalyse™ (Zoetis, Belgium), which contains 5 mg/mL of dinoprost tromethamine.

Estrus monitoring and blood sampling

Estrus characteristics were observed one day following the second administration of PGF2α. The recorded estrus characteristics included vaginal temperature, measured using a digital thermometer (OMRON, China), as well as estrus duration and estrous cycle length. Blood samples were collected from the sows upon the onset of behavioral estrus symptoms. Approximately 1.5 mL of blood was drawn from the marginal ear vein (vena auricularis) using a sterile syringe (OneMed, Indonesia) and collected into ethylenediaminetetraacetic acid (EDTA) tubes (Vaculab®, Sweden). The samples were centrifuged at 3,000 rpm for 15 minutes to separate the plasma (Diatmono et al., 2025). The resulting plasma was aliquoted into three microtubes and stored in a freezer at -20°C until analyzed for blood metabolite levels and reproductive hormone profiles (Ma et al., 2020).

Blood metabolite and hormonal profiling

Plasma biochemical parameters were analyzed via spectrophotometry (Thermo Scientific, Germany) using commercial clinical chemistry kits (Dumolab, Austria) according to previously described methods (Widayati et al., 2024; Diatmono et al., 2025). Specifically, total protein was quantified by the biuret method (540 nm; g/dL). Glucose, cholesterol, and triglycerides were determined using enzymatic colorimetric methods (GOD–PAP and CHOD–PAP, respectively) at 500 nm (mg/dL). Plasma BUN concentrations were measured using the urease–GLDH kinetic method at 340 nm (mg/dL). Reproductive hormone concentrations were quantified via enzyme–linked immunosorbent assay (ELISA) according to the manufacturer’s instructions (DRG International, Germany). FSH (mIU/mL) was measured using kit No. EIA1288, while estradiol (pg/mL) levels were determined using kit No. EIA2693. For both assays, absorbance was read at a wavelength of 450 nm (Hudaya et al., 2020; Sitaresmi et al., 2023).

Statistical analysis

Data were analyzed using one–way analysis of variance (ANOVA) with diet as the fixed factor. When significant differences were detected (p<0.05), means were compared using Tukey’s b test. Results are presented as means ± standard error of the mean (SEM). The statistical analyses were performed using SPSS software, version 26.0 (IBM Corp., USA).

RESULTS

Blood metabolite profiles

Dietary treatments significantly influenced the blood metabolite levels of the sows (Table 3). Total protein levels were significantly higher in the T2 group compared to T0 group (p<0.05), while T1 showed no significant differences from either T0 or T2 groups (p>0.05). Regarding cholesterol levels, T1 and T2 groups did not differ significantly from each other (p>0.05), but were both significantly different from T0 group (p<0.05). BUN levels in the T0 were significantly higher (p<0.05) than those in both the T1 and T2 groups (p>0.05). Conversely, triglyceride levels differed significantly across all treatments (p<0.05), with the highest concentration observed in T2 and the lowest in T0. Additionally, no significant differences in glucose levels were detected among the treatment groups (p>0.05). Overall, sows in the T2 group maintained optimal blood metabolite concentrations, whereas the T0 group recorded the least favorable levels (Table 3).

Reproductive hormone concentrations

The inclusion of local Maluku feed ingredients supplemented with Tenebrio molitor significantly influenced reproductive hormone levels in sows (Table 4). Specifically, FSH levels in the T2 group were significantly higher than those in the T0 group (p<0.05). However, FSH levels in the T1 group showed no significant differences compared to either the T0 or T2 groups (p>0.05). Regarding estradiol levels, significant differences were observed across all treatment groups (p<0.05), whereas the T2 group exhibited the highest estradiol concentrations, while the T0 group recorded the lowest.

Estrus characteristics of sows

The results demonstrated significant variations in estrus characteristics (Table 4). Specifically, the T2 group exhibited a significantly longer estrus duration than the T0 group (p<0.05), whereas did not differ significantly from T1 group (p>0.05). Estrous cycle length was shorter in T2 sows than both the T0 and T1 groups (p<0.05). There was no significant difference in estrous cycle length between the T0 and T1 groups (p>0.05). Furthermore, it was observed that vaginal temperature during estrus did not differ significantly across the dietary treatment groups (p>0.05).

 

Table 3: Blood metabolite levels of sows across different dietary treatment groups (mean ± SEM).

Blood metabolite profiles	Feeding treatment			F Value	P Value
	T0 (n=15)	T1 (n=15)	T2 (n=15)
Total protein (g/dL)	6.28a±0.47	7.50ab±0.45	8.28b±0.47	5.137	0.010
Glucose (mg/dL)	92.96±3.51	100.67±4.82	104.49±4.93	1.713	0.193
Cholesterol (mg/dL)	87.29a±6.56	116.64b±6.09	120.37b±6.10	8.392	0.001
BUN (mg/dL)	18.97b±0.93	15.40a±0.75	14.99a±0.99	5.939	0.005
Triglycerides (mg/dL)	29.35a±1.35	36.03b±1.55	42.00c±1.62	17.454	<0.001

 

abc, different superscripts within the same row indicated significant differences (p<0.05); F Value, the ratio of the mean square between groups to the mean square within groups; p Value, the probability of obtaining the observed results under the null hypothesis; BUN, blood urea nitrogen; g, gram; mg, milligram; and dL, deciliter.

 

Table 4: Reproductive hormone profiles and estrus characteristics of sow (mean ± SEM).

Reproductive hormone and estrus characteristics	Feeding treatment			F value	P value
	T0 (n=15)	T1 (n=15)	T2 (n=15)
FSH (mIU/mL)	1.87a±0.18	2.08ab±0.17	2.63b±0.25	3.548	0.038
Estradiol (pg/mL)	24.11a±1.67	31.74b±1.38	39.27c±2.04	19.300	<0.001
Vaginal temperature (°C)	38.20±0.09	38.36±0.08	37.89±0.65	0.3864	0.682
Estrus duration (h)	70.40a±1.42	72.53ab±1.57	76.46b±1.81	5.725	0.006
Estrous cycle length (d)	20.60b±0.13	20.66b±0.25	19.73a±0.20	6.603	0.003

 

abc, different superscripts within the same row indicated significant differences (p<0.05); F Value, the ratio of the mean square between groups to the mean square within groups; p Value, the probability of obtaining the observed results under the null hypothesis; mIU, mili-international units; pg, picogram; mL, mililiter; °C, degree Celcius; h, hour; and d, day.

 

DISCUSSION

This study shows that feeding sows a local Maluku feed supplemented with Tenebrio molitor meal improves both the physiological status and reproductive performance of sows. These improvements corresponded with higher blood metabolite concentrations (Table 3), increased reproductive hormone levels, and more pronounced estrus characteristics (Table 4). The results indicated that local Maluku feed formulations supplemented with Tenebrio molitor can outperform traditional feeding practices. This formulation is a viable alternative to conventional industry–standard diets and was superior in several aspects.

Sows fed the T2 diet had higher total blood protein concentrations (Table 3). This suggests the T2 diet provided an adequate supply of protein and essential amino acids to support plasma protein synthesis. Furthermore, the results indicate that total protein levels in the T1 and T2 groups are consistent with the findings of Mahardika et al. (2023) with average levels of 7.93±0.53 g/dL, whereas the T0 group exhibited slightly lower concentrations. According to Diatmono et al. (2024), the level of total protein in the blood reflects the efficiency of feed metabolism, where high values indicate that nutrient intake, especially protein and energy, is optimally utilized for anabolism. High total protein levels in T2 treatment indicate an increase in the capacity of plasma protein synthesis by hepatocytes, which is the result of a balance between optimal protein intake, energy, and metabolic status (Bogolyubova et al., 2022). These results may indicated that the local Maluku based diet supplemented with Tenebrio molitor meal can provide an amino acid profile that is close to the physiological needs of sows. As explained by Wu et al. (2014), essential amino acids play a crucial role in the synthesis of structural proteins, hormones, and metabolic enzymes that are indispensable in the process of reproduction and growth.

Elevated blood protein levels are intrinsically linked to metabolic status, organ condition, and reproductive performance. Plasma proteins facilitate the transport of essential nutrients and hormones to ovarian tissue, providing the necessary substrates for steroidogenesis, including the enzymatic conversion of cholesterol into estradiol and progesterone (Sitaresmi et al., 2023; Diatmono et al., 2025). This is consistent with van Milgen and Dourmad (2015), who reported that maintaining optimal protein status in sows stabilizes reproductive hormone levels, thereby shortening the postpartum estrus interval and increasing pregnancy success. High levels of total protein indicate the synchronization of organ condition and hormonal metabolism, which plays an important role in maintaining efficient reproductive functions (Bogolyubova et al., 2022; Frolov et al., 2025). Total protein concentrations also reflect the blood’s capacity for molecular transport (Bogolyubova et al., 2022). Increased total blood protein levels following T2 treatment indicate that liver function and the body’s homeostatic mechanisms are working efficiently, supporting the improvement of metabolic and endocrine systems.

Blood glucose concentrations did not show significant differences across the groups (Table 3), whereas levels remained within the normal range and were consistent with findings previously reported by Mahardika et al. (2023), who observed average glucose levels of 101.55±5.53 mg/dL. Glucose is the main source of energy for almost all tissues of the body, including those that play a direct role in the reproductive system, such as the ovaries, and HPO axis (Schulthess et al., 2025). Glucose plays an important role in supporting the activity of granulosa and theca cells, which are responsible for the synthesis of steroid hormones, such as estradiol and progesterone (Widayati et al., 2019; Hudaya et al., 2020). Glucose serves as a critical metabolic signal within the reproductive system (Scaramuzzi et al., 2015). Stable blood glucose levels within the normal physiological range reflect a positive energy balance (Costermans et al., 2020).

Elevated cholesterol levels were observed in the T1 and T2 groups compared to the T0 group. Nevertheless, cholesterol concentrations across all treatment groups remained within the normal physiological range, consistent with findings by Ezea and Ezike (2024), who observed that blood cholesterol levels in pigs ranged from 107.17±5.85 mg/dL. The elevated plasma cholesterol compared to T0 group, suggest efficient lipid metabolism, wherein dietary fat and energy were effectively partitioned for reproductive hormone synthesis and cellular structural integrity rather than resulting in excessive systemic lipid accumulation (Wang et al., 2022). Cholesterol serves a vital physiological role as the primary precursor for the biosynthesis of steroid hormones, including progesterone, testosterone, and estradiol (Kumala et al., 2022; Diatmono et al., 2025). These hormones play vital roles in regulating the estrous cycle, ovulation, luteal function, and maintenance of pregnancy (Hudaya et al., 2020; Sitaresmi et al., 2023).

Cholesterol is an essential precursor in the ovarian steroidogenesis pathway (Shen et al., 2016). Higher cholesterol levels in T1 and T2 groups than T0 group (Table 3) indicated that substrates for steroid hormone synthesis were available in optimal amounts. Consequently, further increases in plasma cholesterol were unnecessary. This reflects a state of lipid homeostasis, in which cholesterol production and consumption are effectively synchronized with the body’s endocrine demands (Vázquez-Gómez et al., 2018; Roszkos et al., 2023). Cholesterol also serves as a primary structural component of cell membranes, where it maintains fluidity and stability (Zhang et al., 2025). The stability of granulosa and oocyte cell membranes is essential for effective intercellular communication, oocyte maturation, and fertilization. Thus, adequate cholesterol availability supports the structural integrity of ovarian cells and overall oocyte viability (Sitaresmi et al., 2023; Widayati et al., 2024; Zhang et al., 2025).

BUN concentrations were significantly higher in the T0 group compared to the T1 and T2 groups (Table 3), reflecting inefficient dietary protein utilization and elevated hepatic amino acid catabolism (Sitaresmi et al., 2023; Diatmono et al., 2025). Plasma BUN is the primary end product of amino acid catabolism, where amino groups (-NH2) released during hepatic deamination are converted into ammonia (NH3). This toxic ammonia is subsequently detoxified into urea via the ornithine cycle and excreted by the kidneys (Ma et al., 2020; Kumala et al., 2022). The increased BUN levels in the T0 group indicate a metabolic state where amino acids were oxidized for energy, likely due to an imbalanced amino acid profile or insufficient non–protein energy in the traditional feed formulation rather than being utilized for anabolic processes. The most critical negative impact of elevated BUN levels pertains to reproductive performance, particularly in sows (Kim et al., 2023).

While BUN concentrations remained within the normal physiological range, the levels observed in the T0 group were higher than those reported in previous studies by Kim et al. (2023), with BUN levels ranging from 12.76±2.30 mg/dL. High systemic urea concentrations can induce microenvironmental alterations within the reproductive tract, such as a reduction in uterine fluid pH, which can be embryotoxic. Such conditions may inhibit blastocyst development and increase the incidence of early embryonic death during the initial stages of gestation (Kim et al., 2023; Widayati et al., 2024; Sanz-Fernández et al., 2024). Furthermore, metabolic stress resulting from an excessive nitrogen load can disrupt the endocrine balance regulating ovarian function, thereby reducing the long–term productivity of the livestock (Sitaresmi et al., 2023; Widayati et al., 2024). Consequently, the lower BUN levels observed in the T1 and T2 groups suggest that the diets can effectively optimized nitrogen retention and provided a more favorable physiological environment for reproductive success.

Triglyceride levels differed markedly across the T0, T1, and T2 groups, with the highest concentrations observed in the T2 group. Despite this increase, the observed triglyceride levels remained relatively low compared to standard reference ranges. However, the values in the T2 group were consistent with those previously reported by Mahardika et al. (2023), which reported triglyceride levels of 47.16±4.18 mg/dL. As the primary medium for energy storage, these lipids are stored as droplets in adipose tissue (Ghio et al., 2011). The higher tryglicerides levels at T2 indicates that energy obtained from the feed likely exceeded immediate metabolic requirements, thereby promoting a positive energy balance. Such stored reserves are vital for ovarian function, providing the metabolic support necessary for folliculogenesis and the successful maturation of follicles (Yu et al., 2024). This reflects the role of triglycerides as metabolic signals of metabolic integration within the reproductive system (Qing et al., 2022; Herdis et al., 2025).

The higher triglycerides observed in T2 (Table 3), while remaining within physiological limits, suggest a state of positive energy balance rather than lipid overload. This distinction is critical, while moderate levels support function, chronic hyperlipidemia is known to impair energy metabolism, induce insulin resistance, and trigger oxidative stress in reproductive tissues (Yang et al., 2023). Furthermore, triglycerides serve as a primary energy substrate for steroidogenesis within granulosa cells (Gugliucci, 2023). The energy derived from lipid oxidation is essential for the conversion of cholesterol into vital steroid hormones (Przygrodzka et al., 2024; Diatmono et al., 2025). Ultimately, this heightened metabolic activity reflects an optimization of ovarian function, directly contributing to improved estrus quality and higher ovulation success rates.

Dietary treatments influenced FSH and estradiol concentrations (Table 4). These findings are comparable to those of Noguchi et al. (2013), who reported that FSH levels in sows during estrus averaged 2.50±0.22 mIU/mL, while estrogen levels reached 33.50±4.50 pg/mL. In the present study, FSH concentrations were highest in the T2 group, suggesting that the specific dietary equilibrium of energy and protein in this treatment served as a primary driver for bolstering reproductive endocrine activity along the HPO axis (Herdis et al., 2025). This optimized metabolic profile likely acted as a systemic signal, stabilizing the pulsatile secretion of gonadotropin–releasing hormone (GnRH) from the hypothalamus and enhancing pituitary sensitivity to endogenous stimuli (Knox, 2023; Sitaresmi et al., 2023). This enhanced pituitary sensitivity likely facilitates the recruitment of primordial follicles and the subsequent selection of the dominant follicle (Knox, 2023). At the cellular level, FSH stimulates granulosa cell proliferation and the critical upregulation of luteinizing hormone (LH) receptors, which primes the follicle for the ovulatory surge (Kishi et al., 2018; Padmanabhan and Cardoso, 2020).

Estradiol concentrations were higher in T2 sows than in T0 or T1 sows (Table 4), the levels observed in the T1 and T2 groups were comparable to those reported in a previous study by Noguchi et al. (2013). This suggests that these sows entered a more robust and mature follicular phase, marked by heightened biosynthetic activity within the granulosa cells (Costermans et al., 2020). This suggests the T2 diet, which combined Maluku local ingredients with Tenebrio molitor provided the requisite protein, energy, and essential fatty acids to adequately fuel ovarian steroidogenesis. Such a surge in estradiol synthesis is likely a direct consequence of increased aromatase enzyme activity, reflecting a highly sensitive response to FSH stimulation and confirming that the dominant follicles reached peak maturation (Schütz and Batalha, 2024). The observed hormonal patterns within the HPO axis suggest a coordinated transition from follicle recruitment to selection, coinciding with nutrient availability that appears sufficient to support the energetic requirements of steroidogenesis (Costermans et al., 2020).

The significantly higher estradiol concentrations observed in the T2 group may provide the endocrine environment necessary to facilitate the preovulatory LH surge. Previous studies indicate that elevated systemic estradiol is a prerequisite for ovulation and the subsequent development of a functional CL (Christian and Moenter, 2010; Costermans et al., 2020). Beyond these internal mechanisms, the elevated estradiol levels in T2 group also manifested in stronger behavioral indicators of estrus (Sitaresmi et al., 2020). By stimulating estrogen receptors within the central nervous system, this hormonal peak drives the physical expressions of mating readiness, including vulvar swelling and the lordosis reflex (Glencorse et al., 2025). Consistent with Noguchi et al. (2010), this robust behavioral expression serves as a reliable proxy for successful ovulation, indicating that the T2 treatment successfully optimized both the physiological and behavioral components of reproductive performance.

Vaginal temperature did not differ significantly across all treatment groups (Table 4). These consistent values likely reflect the intensified endocrine activity and metabolic demands inherent to the estrus phase, regardless of dietary treatment (Weng, 2020; Glencorse et al., 2025). This thermal shift is a direct physiological consequence of surging preovulatory estradiol, which drives peripheral vasodilation and enhances blood flow to the reproductive tract (Simões et al., 2014). This increased perfusion facilitates the rapid delivery of oxygen and metabolic substrates to the ovaries and vaginal tissues while simultaneously increasing local heat transfer, thereby raising the localized temperature. Such fluctuations align with established physiological responses to the hormonal peaks preceding ovulation (Sitaresmi et al., 2020; Weng, 2020). Estradiol–induced capillary expansion and increased endothelial permeability lead to interstitial fluid accumulation and a concomitant rise in vulvar and vaginal heat (Scolari et al., 2011). The increased vaginal temperature across all groups is consistent with reports that these thermal changes occur prior to ovulation, coinciding precisely with the peak secretion of estradiol and LH in the follicular phase compared to the luteal phase (Simões et al., 2014; Glencorse et al., 2025).

The duration of estrus was significantly extended in the T2 compared to the T0 group, while the T1 di not differ significantly from both T0 and T2 sows (Table 4). These results suggesting a more stable and synchronized endocrine profile. This reflects higher preovulatory estradiol concentrations, which sustain sexual receptivity by maintaining persistent hormonal signaling during the preovulatory window (Madej et al., 2005; Simões et al., 2014). Mechanistically, estradiol serves as a key regulator of the estrus phase, exerting positive feedback on the hypothalamus to increase GnRH pulse frequency and stimulate the LH secretion required for ovulation (Noguchi et al., 2010; Clarke, 2018). This longer estrus duration suggests increased hypothalamic sensitivity to circulating estrogens, where the activation of estrogen receptors in key neural pathways modulates sexual behavior to expand the window of receptivity (Madej et al., 2005). Consequently, the superior estradiol profile in the T2 group not only facilitates the physiological trigger for ovulation but also intensifies the behavioral cues essential for effective reproductive management and timing of insemination.

The estrous cycle length was significantly reduced in the T2 group compared to T0 and T1 groups (Table 4), suggesting heightened efficiency in follicular recruitment and ovarian turnover. Consistent with (Knox, 2019), this abbreviated cycle suggests superior hormonal synchronization between FSH, LH, and estradiol, facilitating a rapid transition to follicular development following CL regression. Such a rapid recovery rate is likely underpinned by the favorable metabolic and endocrine environment observed in T2 group. Close coordination between gonadotropins and steroid hormones is necessary for maintaining regular reproductive cyclicity, as disruptions in luteolysis or GnRH pulsatility typically extend the inter–estrus interval (Soede et al., 2011; Knox, 2019). The shorter estrous cycle in T2 sows coincided with optimal concentrations of blood metabolite profiles, evidenced by higher circulating levels of total protein, glucose, cholesterol, and triglycerides (Table 3). This metabolic profile effectively facilitates the transition between cycles by accelerating follicle recruitment and maturation (Bogolyubova et al., 2022; Knox, 2023). Consequently, the shortened estrous cycle interval observed in the T2 group serves as a hallmark of high endocrine efficiency, indicating a physiological system effectively primed for successive ovulatory events.

CONCLUSIONS AND RECOMMENDATIONS

This study shows that feeding sows a local Maluku feed containing 7% Tenebrio molitor meal during the mating period optimizes blood metabolite profiles and augments reproductive hormone secretion. These physiological changes were accompanied by more pronounced estrus signs, including longer estrus duration, and shorter estrous cycle. This feed formulation is a viable alternative to conventional commercial feeds, and outperformed traditional diets. Therefore, further study is warranted to evaluate the impact of local Maluku diets and Tenebrio molitor supplementation on the overarching productivity of sows.

ACKNOWLEDGMENTS

The authors are grateful to the National Research and Innovation Agency of Indonesia (BRIN) for supporting this study through its Degree by Research (DBR) program. We also thank the local farmers in Suli Village and the Tropical Animal Research Center Laboratory (TARC), Faculty of Animal Science, UGM, for providing facilities for this study.

NOVELTY STATEMENT

This study combines local Maluku feed ingredients with Tenebrio molitor supplementation for sows during the mating period. We compared this indigenous–based diet against both traditional farm diets and commercial feeds. By assessing blood metabolic profiles, including total protein, glucose, cholesterol, BUN, and triglycerides with key reproductive hormones, including FSH and estradiol, also clinical estrus responses, this study offers a new perspective on optimizing porcine reproductive efficiency through sustainable local resources.

AUTHOR’S CONTRIBUTION

DTW, ZZ, HH, and MAdaC conceptualized and designed the study. Fieldwork and experimental procedures were carried out by MAdaC, SS, PRM, and PIS. Data curation, formal analysis, literature search, and the initial drafting of the manuscript were performed by MAdaC, DFFD, PIS, and FGP. Results interpretation, revision, and final editing were conducted by RN, DFFD, FGP, MAdaC, and DTW. Project supervision was conducted by DTW, ZZ, and HH, while resource coordination was managed by DTW.

Ethical approval

All procedures involving animals in this study were reviewed and formally approved by the Animal Ethics Committee of the National Research and Innovation Agency (BRIN) of the Republic of Indonesia (Approval No. 048/KE.02/SK/3/2025). The experimental protocols were conducted in strict accordance with institutional and national guidelines for the care and use of livestock. These measures were implemented to ensure compliance with animal welfare standards throughout the study period.

Generative AI and AI assisted technology statement

Generative AI was used to assist with language editing and clarity. The authors manually reviewed and edited the manuscript to produce the final version.

Conflict of interest

The authors have declared no conflict of interest.

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