Nyamplung Seed Meal (Calophyllum inophyllum) as an agro-industrial by-product feed resource: Impact on nutrient utilization and lactation performance in sapera dairy goats

Edi Prayitno, Agung Purnomoadi, Endang Purbowati and Rudy Hartanto

Department of Animal Science, Faculty of Animal and Agricultural Sciences, Universitas Diponegoro, Semarang, Central Java, Indonesia 50275
e.prayitno.undip@gmail.com

Abstract

Nyamplung seed meal is an abundant agro-industrial by-product in Indonesia with potential application as an alternative feed resource for lactating dairy goats. This study was conducted to determine the effect of graded inclusion levels of nyamplung seed meal (NSM) in the diet of lactating Sapera goats on feed intake, nutrient digestibility, milk production and milk composition. Five complete pelleted diets were formulated with graded inclusion levels of NSM as a partial replacement of the basal diet at 0%, 15%, 20% and 25% of dry matter, designated as Control, NSM15, NSM20 and NSM25, respectively. Twenty-eight lactating Sapera goats aged 2–2.5 years, with body weights (BW) ranging from 52.75–80.50 kg, an average day in milk (DIM) of 60 ± 5 days and milk production ranging from 550–1942 g/day, were assigned to a randomized complete block design (RCBD) with 4 treatments and 7 replicates. Goats were blocked based on daily milk production. Data were analyzed using one-way analysis of variance followed by Tukey's test. The findings indicated that NSM inclusion significantly increased the intake of dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF) and total digestible nutrients (TDN) (p<0.05). Apparent digestibility of DM, CP, crude fiber (CF), EE and TDN was also significantly affected by NSM inclusion (p<0.05). Milk production, milk protein content, lactose and total solids (TS) were greater in NSM-inclusion goats relative to the control, with milk production efficiency increasing significantly with increasing NSM inclusion levels (p<0.05). This study found that NSM is a suitable alternative feed ingredient for Sapera dairy goats and its inclusion at up to 25% DM is recommended, as it improves milk production efficiency and milk quality relative to the control. Furthermore, the use of NSM in dairy goat diets represents a promising and sustainable alternative feed source.

Keywords: Nyamplung seed meal, feed consumption, feed digestibility, milk production, milk production efficiency

Introduction

Goat farming plays a strategic role in the food security system of many developing countries due to its high adaptability and relatively rapid reproductive cycle. This sector not only supports the community's nutritional needs but also serves as an economic pillar for small-scale farmers in various rural areas. Sapera goats are a breed resulting from the crossbreeding of Saanen goats and Peranakan Ettawa (PE), which have been widely raised for their advantages in milk production and environmental adaptability (Prayitno et al 2021). The milk production of Sapera goats can reach 0.558-2.46 kg/day (Nuswantara et al 2024; Prima et al 2025; Supriyati et al 2016).

The sustainability of the ruminant livestock sub-sector is currently threatened by limited access to high-quality, sustainable feed resources, a consequence of climatic conditions and resource scarcity (Cherdthong, 2025). Farmers require affordable, locally sourced feed to improve the productivity and profitability of their livestock operations (Liang & Paengkoum, 2019; Purbowati et al 2025). The utilization of agro-industrial by-products as feed ingredients for ruminants has become a strategic issue in the development of sustainable livestock systems to meet animal nutritional needs, maximize local resources and reduce environmental impact (Alimi et al 2024; Priyanka et al 2024).

A considerable amount of agro-industrial by-products with high potential as alternative ruminant feedstocks is generated by the Indonesian vegetable oil processing sector. A prominent example is nyamplung (Calophyllum inophyllum) seed meal or NSM, which is obtained as a co-product of the seed oil extraction activity. Agricultural and agro-industrial residues have gained increasing attention as alternative feedstocks due to their widespread availability, cost-effectiveness and potential contribution to sustainable livestock production systems (Purbowati et al 2025). Nyamplung seed meal (NSM) is characterized by a high fiber content and the presence of plant secondary metabolites, particularly phenolic compounds, which can modulate methanogenic archaea populations, thereby altering ruminal fermentation patterns and mitigating methane emissions (Paradhipta et al 2025)

Chemical analysis shows that NSM contains crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) at approximately 21.93%, 6.7% and 42.32%, respectively. In addition, NSM contains total phenols (3.37-6.58%), total flavonoids (1.13-1.65%), saponins (0.57-0.87%), condensed tannins (0.23-0.44%) and hydrolyzable tannins (0.21-0.51%) (Prayitno et al 2025; Umroni et al 2024). Previous in vitro studies have also shown that using NSM at levels up to 25% (dry matter basis) in the diet can improve feed digestibility and reduce methane emissions without adversely affecting rumen fermentation (Paradhipta et al 2023; Prayitno et al 2025).

The potential of NSM as a ruminant feed has been reported in previous studies; however, to date, it has been limited to in vitro analysis and a systematic evaluation of its effects on digestibility, production performance and goat milk composition has not yet been conducted. Therefore, this study was conducted to examine the effect of NSM inclusion in the diet of lactating Sapera goats on feed intake, digestibility, production performance and milk composition. The results of this study are expected to inform a new strategy for supplying alternative feeds to dairy goats using local resources.

Materials and methods

Ethics committee and experiment location

The study was conducted at the UD Mitra Agroabadi goat farm located in Barukan Village, Semarang Regency, Central Java, Indonesia (7°21'43.7" S, 110°32'24.8" E, 182 m above sea level). This study was conducted in accordance with animal welfare regulations and procedures approved by the Animal Ethics Committee of the Faculty of Animal and Agricultural Sciences, Diponegoro University (Ethical Approval Number: No 60-12).

Nyamplung management

Nyamplung (Calophyllum inophyllum) is a well-known tropical forest tree in Indonesia, prized for its timber in construction and its seeds for biodiesel production (Photo 1).

a. Nyamplung tree	b. Nyamplung fruit	c. Dried nyamplung fruit
Photo 1. Calophyllum inophyllum L. (nyamplung) tree observed during field research. Source: Photograph by the authors.

Figure 1. Extraction of Nyamplung Oil and Its By-Product (Nyamplung Seed Meal)

The extraction of seed oil generates a dense residue known as nyamplung seed meal (NSM) (Figure 2), which serves as an alternative feedstuff for livestock. For this experiment, NSM was sourced as an agro-industrial by-product from a processing plant in Cilacap Regency, Central Java. The processing workflow involved dehulling, cleaning and drying the seeds prior to mechanical extraction via a screw expeller. The experimental diets containing the processed NSM were subsequently pelletized using a 6-mm die configuration. Following pelletization, the feeds were air-dried and maintained in hermetic containers until the animal feeding trials. To guarantee nutritional uniformity and experimental consistency, the remaining basal ingredients—comprising dried water spinach, peanut hulls, wheat pollard, cassava meal, soybean meal (SBM) and a mineral premix—were purchased Andini Store (Semarang Regency, Indonesia)

Animals and experimental design

The study used 28 lactating Sapera goats aged 2-2.5 years, with body weights ranging from 52.75 to 80.50 kg, an average day in milk (DIM) of 60 ± 5 days and milk production ranging from 550 to 1942 g/day. The goats were grouped based on daily milk production. The experiment employed a randomized complete block design (RCBD) with four dietary treatments and seven goat groups. The dietary treatments were randomly assigned to the animals within each group.

The study lasted for 42 days and included a 14-day adaptation period for the goats to adjust to their environment, management and experimental feed; the experiment itself was conducted over 28 days. All goats were individually placed in metabolic cages, in which clean water was always accessible. The feeding routine was established for 07:00 and 16:00 each day. Milking was performed manually at 06:00 and 15:00 and teat dipping with 0.5% iodine-glycerin was performed before and after milking. Milking and hygiene protocols to prevent udder infections were implemented in accordance with the procedures described by Prayitno et al (2023).

Sample preparation and chemical analysis

Feed ingredient samples were dried in a forced-air oven at 55 °C until constant weight was achieved, ground to a uniform particle size and passed through a 1 mm mesh sieve prior to chemical analysis. The proximate composition of the feed ingredients used in the present study is summarized in Table 1.

Proximate composition, encompassing dry matter (DM), ash, crude protein (CP), ether extract (EE) and crude fiber (CF), was determined following the standard analytical procedures outlined by the Association of Official Analytical Chemists (AOAC, 2005). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents were analyzed according to the sequential detergent fiber method described by Van Soest et al (1991).

Pelleted diet preparation and experimental feed formulation

Pelleted diets were prepared by accurately weighing all feed ingredients according to each treatment formulation, with NSM incorporated as the partial replacement ingredient. All dry ingredients were ground to pass through a ±1 mm sieve and thoroughly blended before water was added at approximately 15–20% of total weight to achieve the appropriate moisture content for pellet manufacturing. The conditioned feed mash was then processed through a pellet mill equipped with a ±6 mm die. Pelleting was carried out under moderate temperatures produced by mechanical friction, without additional heating or excessive pressure, to minimize potential nutrient degradation. The resulting pellets were dried in a forced-draft oven at 60 °C for 24 h until a stable moisture content was reached, cooled to room temperature, sealed in airtight containers and stored under dry conditions until use in the in vivo trial.

The experimental diets were formulated with graded inclusion levels of NSM as a partial replacement of the complete feed, with all dietary treatments expressed on a dry matter basis and designed to meet the nutrient requirements for maintenance and lactation in dairy goats as recommended by NRC (2007). The proximate and fiber composition of each dietary treatment is presented in Table 2.

Intake and apparent digestibility of nutritional components

The experimental feed was formulated as a total mixed ration (TMR) in pellet form on a dry matter (DM) basis to meet the daily milk production requirements of lactating does. Feed allowance was set at 3% of body weight (BW) on a DM basis, ensuring adequate nutrient supply while maintaining uniform feed intake and avoiding palatability-related bias. Dry matter (DM) intake was determined by complete feed consumption, quantified in g/day. To determine the nutrient intake for crude protein (CP), crude fiber (CF), neutral detergent fiber (NDF) and acid detergent fiber (ADF), one must multiply dry matter intake by the relevant nutrient concentration in grams per day. Digestibility assessment utilized the total collection method over 7 days during the experimental phase. Throughout this interval, all feed and droppings were amassed, sampled and assessed for their chemical elements. The digestibility figure is derived by evaluating the ratio of the nutrients that have been digested, defined as the total nutrient intake minus the fecal output, divided again by the nutrient intake, with the outcome expressed in percentage terms (Tillman et al 1984).

Production, composition and quality of the milk

Milk production was determined by aggregating morning and afternoon yields. A 500-g milk sample was procured from each goat, representing a composite of both milking sessions. The milk sample was placed in a plastic bottle and stored in a cooler box for transport to the laboratory for analysis. The milk protein content, fat, lactose, specific gravity, total solids (TS) and solid non-fat (SNF) were analyzed using a milk analyzer at the Meat and Dairy Production Laboratory, Faculty of Animal and Agricultural Sciences, Diponegoro University. Milk production corrected for 4% fat (4%FCM) was calculated using the following formula (NRC, 2001): 4%FCM (fat-corrected milk) = 0.4 × milk production (g) + 15 × milk fat (g).

Data analysis

The obtained data were analyzed using analysis of variance (ANOVA) at a 5% significance level. If significant results were found, Tukey’s post hoc test was conducted using Jamovi 2.7 (Jamovi, 2025).

Results and discussion

Intake and apparent digestibility

Overall, the inclusion of NSM significantly increased the intake of most nutrients. Intake of CP, CF, EE and NDF differed significantly (p< 0.05) with NSM treatment, whereas DM intake did not differ significantly (p=0.748). The inclusion of NSM in the feed resulted in an increasing trend in the intake of CP, CF, EE and NDF. The NSM25 group showed significantly different intakes compared with the control, with CP, CF, EE and NDF intakes of 331.57, 447.49, 123.43 and 960.50 g/day, respectively. This is because NSM contains higher nutrient levels than the basal diet. The content of CP, CF, EE and NDF (NSM vs. basal diet) was, respectively, 21.9% vs. 14.3%; 25.1% vs. 20.8%; 6.70% vs. 3.53%; and 42.3% vs. 38.6%, so the inclusion of NSM increased the nutritional content of the feed, which ultimately affected the amount of nutrients consumed. In this study, TDN intake differed significantly (p=0.047) among the treatments, with the highest TDN intake observed in the NSM20 treatment (1508.43 g/day). This indicates that nutrient intake is influenced by the nutrient content of the ration, which, in turn, affects TDN intake.

All digestibility parameters differed among treatments (p<0.05), confirming that NSM inclusion has a structural impact on feed utilization efficiency. DM, CP and CF digestibility peaked in the NSM20 treatment and tended to decrease slightly with the increase of NSM to 25%. The NSM20 treatment yielded the highest DM digestibility (p=0.005) among all treatments. Differences in feed composition due to NSM inclusion led to variations in digestibility. As NSM inclusion increased to 20%, DM digestibility also increased; however, with NSM25, digestibility began to decline. It is presumed that the 20% inclusion level in this study provided a nutrient composition (CP, NDF and TDN) that resulted in optimal digestibility.

The digestibility of CP in NSM15, NSM20 and NSM25 was higher (p=0.000) compared to the control (80.82%, 82.85% and 81.35% vs. 77.62%). The same trend was observed in CF digestibility, as NSM inclusion affected rumen fiber digestion. NSM inclusion produced higher CF digestibility in NSM20 and NSM25 (p=0.000) than in the control (57.92% and 53.95% vs. 32.95%). The high CF digestibility in NSM20 and NSM25 was attributable to a more favorable fiber fraction profile, particularly the NDF-to-ADF ratio. A higher hemicellulose content relative to cellulose and lignin facilitated fermentation by rumen microbes, whereas NSM15 and the control showed a poorer fiber fraction profile than NSM20. This phenomenon is consistent with the findings of Da Cruz et al. (2021) and Weimer (2022), which report that lignin in ADF acts as a limiting factor in fiber digestion because it can associate with fiber components, thereby limiting microbial access and reducing fiber digestibility. Ismartoyo et al. (2022) affirmed that the NDF and ADF profiles of feed are closely related to feed digestibility in goats, particularly the fiber component.

NSM inclusion resulted in different EE consumption (p=0.000). The inclusion of NSM at up to 20% did not negatively affect DM digestibility. EE consumption in the control, NSM15 and NSM20 groups (68.08, 74.79 and 90.14 g/day, respectively) was lower than that reported by Ferreira et al. (2022), who stated that EE consumption up to 107.8 g/day in dairy goats does not affect DM digestibility; on the contrary, digestibility is more influenced by substrate characteristics, particularly NDF and ADF content. However, in the NSM25 group, with EE consumption of 123.45 g/day (6.33% DM), digestibility began to decline. This is consistent with the reports by Frank et al. (2022) and Hussein et al. (2024), who state that feed fat concentrations above 6% DM can reduce overall feed digestibility.

Calcium (Ca) and phosphorus (P) intake among the treatments did not differ significantly (p > 0.05). Ca intake ranged from 29.89 to 31.68 g/day, while P intake ranged from 14.27 to 15.13 g/day, with a Ca:P ratio of 2:1. The goats consumed sufficient amounts of Ca and P, exceeding the National Research Council (NRC) recommendations, which are 9.5-11 g/day for Ca and 6.5-7.5 g/day for P (NRC, 2001). Ca and P are essential macro-minerals for physiological processes, growth, metabolism, milk production and animal health, as they serve as cofactors in carbohydrate, protein and fat metabolism, as well as in animal immunity (Wu, 2022).

Milk Production and Composition

Overall, NSM inclusion increased milk production in Sapera goats compared with the control. Milk production in this study ranged from 1105 to 1408 g/day, which was slightly higher than the results reported by Hermawati and Nuraeni (2024), who recorded Sapera goat milk production of 1020-1150 g/day. Increasing the level of NSM inclusion had a significant positive effect on milk production volume, beginning at NSM20 (p=0.000). Milk production at NSM15 did not differ significantly from that at the control (1106 g/day), with a trend toward higher values at NSM20 (1418 g/day) and NSM25 (1408 g/day). In contrast, the production of fat-corrected milk (4% FCM) also showed a similar trend, with significantly higher values (p=0.000) at NSM25 (1591 g/day) and NSM20 (1497 g/day) compared to NSM15 (1159 g/day) and the control (1051 g/day).

This finding supports the hypothesis that NSM can enhance the nutritional value of feed, thereby increasing CP and TDN intake, which, in turn, results in higher milk production in the control group. The TDN intake data (Table 3) support the observed milk production levels in this study. The NSM20 treatment showed the highest TDN intake (p=0.047) and resulted in higher milk production compared to the control and NSM15 (p=0.003). According to NRC (2007), the nutrient requirements for lactating goats with an average body weight of 65 kg and a milk production of 1.5 L/day are 250 g/day of CP and 1,250 g/day of TDN, respectively. The TDN intake in this study followed the NRC recommendations, with CP intake ranging from 275.40 to 328.47 g/day and TDN intake ranging from 1264.95 to 1508.43 g/day. TDN and CP levels in goat feed strongly determine milk production. Vicente et al. (2020) reported that goats fed diets containing 70-75% TDN produced more milk than those fed 65% TDN.

The results showed that the inclusion of NSM resulted in a positive trend in the composition of the goat milk produced, as reflected in higher levels of protein, lactose, total solids (TS) and solid non-fat (SNF) (p<0.05) in the feed treatments with NSM inclusion compared to the control (Table 4). There was a fluctuation in protein content, with the highest protein level numerically obtained in the NSM15 treatment (3.90%). However, at a higher level (NSM25), the protein level decreased to 3.63%, which is still equivalent to that of the control. The milk fat content showed no significant difference (p=0.127) among the treatments. However, the numerical trend increased from 4.21% (control) to 4.85% (NSM25). This is a positive finding, as it indicates that NSM does not interfere with rumen fermentation and that it produces sufficient acetic acid as a precursor for milk fat. Total solids (TS) increased further with the inclusion of NSM (p=0.007). The increase in TS indicates that the milk produced contains better nutrients than that of the control. The overall improvement in TS and SNF, therefore, reflects not only better milk quality but also a more productive lactation response. Figure 4 further demonstrates this trend, showing that daily milk production increased quadratically with higher NSM inclusion levels (R² = 0.83), confirming the beneficial role of NSM as a dietary supplement in supporting both milk quality and quantity in Sapera dairy goats.

Figure 2. Effect of nyamplung seed meal (NSM) inclusion level (%) on daily milk production (g/day) in Sapera dairy goats

Milk production efficiency represents the relationship between milk yield and DM intake. The inclusion of NSM in the feed increased the nutrient content of the feed, as reflected in the CP and TDN content and intake. An increase in TDN intake is reflected in an increase in milk production, with milk production efficiency in NSM25 being better than that in the control (0.72 g/gDMI). Milk production efficiency was indirectly greatly influenced by TDN intake, as shown by the results of this study. This condition is similar to that reported by Kholif et al (2020), namely that milk production efficiency in dairy goats is greatly influenced by TDN intake.

Conclusions

The use of NSM in the diets of lactating goats improved nutrient intake, apparent digestibility, milk production and several milk composition traits. In general, NSM enhanced the nutritional value of the ration and supported better lactation performance than the control diet.

Therefore, the inclusion of up to 25% DM in dairy goat feed is recommended, as NSM can produce better production efficiency and milk quality compared to the control. These findings indicate that NSM is a promising agro-industrial by-product feed resource for dairy goats and may contribute to more sustainable feeding systems based on locally available feed resources in tropical areas.

Acknowledgement

The authors are grateful for the financial support from the Indonesian Education Scholarship (grant number: 02163/BPPT/BPI.06/9/2023), provided by the Center for Higher Education Funding and Assessment (BPPT), Ministry of Higher Education, Science and Technology and the Endowment Fund for Education Agency (LPDP), Ministry of Finance of the Republic of Indonesia

References

Alimi N, Assani, A S, Sanni Worogo, H, Baco, N M and Traoré, I A 2024 Livestock feed resources used as alternatives during feed shortages and their impact on the environment and ruminant performance in West Africa: A systematic review. Frontiers in Veterinary Science, 11, 1352235. https://doi.org/10.3389/fvets.2024.1352235

AOAC 2005 Official Methods of Analysis of the Association of Official Analytical Chemists (17th ed.). Association of Official Analytical Chemists Inc.

Cherdthong, A 2025 An Overview of Alternative Protein Sources for Ruminants in the Tropical Area. Annals of Animal Science, 25(1), 103-118. https://doi.org/10.2478/aoas-2024-0049

Da Cruz C, H, Santos S A, De Carvalho G G P, Azevedo J A G, Detmann E, Valadares Filho, S D C, Mariz L D S, Pereira E S, Nicory I M C, Tosto M S L and Alba H D R 2021  Estimating digestible nutrients in diets for small ruminants fed with tropical forages. Livestock Science, 249, 104532. https://doi.org/10.1016/j.livsci.2021.104532

Ferreira F G, Leite L C, Alba H D R, Pina D D S, Santos S A, Tosto M S L, Rodrigues C S, De Lima Júnior D M, De Oliveira J S, De Freitas Júnior J E, De C. Mesquita B M A and De Carvalho G G P 2022 Palm Kernel Cake in Diets for Lactating Goats: Intake, Digestibility, Feeding Behavior, Milk Production and Nitrogen Metabolism. Animals, 12(18), 2323. https://doi.org/10.3390/ani12182323

Frank E, Livshitz L, Portnick Y, Kamer H, Alon T and Moallem U 2022 The Effects of High-Fat Diets from Calcium Salts of Palm Oil on Milk Yields, Rumen Environment and Digestibility of High-Yielding Dairy Cows Fed Low-Forage Diet. Animals, 12(16), 2081. https://doi.org/10.3390/ani12162081

Hartadi H, Reksohadiprodjo S and Tillman A D 2005 Tables of Feed Composition for Indonesia. Gadjah Mada University Press.

Hermawati N F and Nuraeni N 2024 Studi Bobot Badan Ternak Terhadap Produksi Susu Kambing Sapera (Capra aegagrus hircus) di Peternakan El Farm Yogyakarta:  Jurnal Ilmiah Ilmu-Ilmu Peternakan, 27(1), 80-86. https://doi.org/10.22437/jiiip.v27i1.32674

Hussein S M, Aguerre M J, Jenkins T C, Bridges W C and Lascano G J 2024 . Screening Dietary Fat Sources and Concentrations Included in Low- and High-Forage Diets Using an In Vitro Gas Production System. Fermentation, 10(10), 506. https://doi.org/10.3390/fermentation10100506

Ismartoyo I, Syahriani S, & Sarwan S 2022 The Feed ADF and NDF Digestibility of Goat Fed Four Difference Diets. Hasanuddin Journal of Animal Science (HAJAS), 4(1), 41-47. https://doi.org/10.20956/hajas.v4i1.20192

Jamovi 2025 Jamovi (Version 2.7) [Computer software]. https://www.jamovi.org.

Kholif A E, Gouda, G A and Hamdon H A 2020 Performance and Milk Composition of Nubian Goats as Affected by Increasing Level of Nannochloropsis oculata Microalgae. Animals, 10(12), 2453. https://doi.org/10.3390/ani10122453

Liang J B and Paengkoum P 2019 Current status, challenges and the way forward for dairy goat production in Asia - conference summary of dairy goats in Asia. Asian-Australasian Journal of Animal Sciences, 32(8), 1233-1243. https://doi.org/10.5713/ajas.19.0272

NRC 2001 Nutrient Requirements of Dairy Cattle: Seventh Revised Edition, 2001 (p. 9825). National Academies Press. https://doi.org/10.17226/9825

NRC 2007 Nutrient Requirements of Small Ruminants: Sheep, Goats, Cervids and New World Camelids (p. 11654). National Academies Press. https://doi.org/10.17226/11654

Nuswantara L K, Pangestu E, Christiyanto M, Pratomo S D and Muhtaromah E Z 2024 Digestibility and Milk Production of Dairy Goat Fed Concentrate Contain Tree Legumes at Various Levels. Advances in Animal and Veterinary Sciences, 12(2). https://doi.org/10.17582/journal.aavs/2024/12.2.355.362

Paradhipta D H V, Hanim C, Agus A, Leksono B, Umroni A, Maharani S, Wardani A R D and Anam M S 2023 Study of nyamplung (Calophyllum inophyllum) kernel cake as an alternative protein source for ruminant feed and its effect on methane emission through in vitro. 35. https://www.lrrd.org/lrrd35/11/cont3511.html

Paradhipta D H V, Firdaus N, Ashshaadiq I H, Agus A and Leksono B 2025 Effects of Tamanu Kernel Cake from Plantation By-product on Ruminal Digestibility and Methane Emission.Pertanika Journal of Tropical Agricultural Science, 48(4). https://doi.org/10.47836/pjtas.48.4.06

Prayitno E, Hartanto R and Harjanti D W 2021 Physicochemical and Microbiological Appearance of Sapera Goat’s Milk on Frozen Storage. Jurnal Sain Peternakan Indonesia, 16(4), 308-314. https://doi.org/10.31186/jspi.id.16.4.308-314

Prayitno E, Hartanto R and Harjanti D W 2023 Budidaya Kambing Perah Di Daerah Tropis (1st ed.). Deepublish Publisher.

Prayitno E, Purnomoadi A, Hartanto R, Purbowati E, Adiwinarti R and Zidane A 2025 Nyamplung seed cake as a dietary supplement for dairy goats: In vitro digestibility and fermentability analysis. Journal of Advanced Veterinary Research, 15(6), 771-775. Scopus. https://www.scopus.com/inward/record.uri?eid=2-s2.0-105025234707&partnerID=40&md5=5131d54578c89142144d77c3ef70c73a

Prima A, Prayitno E, Hidyatulloh A, Harjanti D W and Hartanto R 2025 Nutritional drivers of milk yield and composition in Sapera dairy goats: Insights from smallholder farms in Central Java, Indonesia. Journal of Advanced Veterinary Research, 15(6), 909-912. Scopus. https://www.scopus.com/inward/record.uri?eid=2-s2.0-105025229428&partnerID=40&md5=3782d869494cba43d8d35d5fe1ec95bc

Priyanka G, Singiri J R, Adler-Agmon Z, Sannidhi S, Daida S, Novoplansky N and Grafi G 2024 Detailed analysis of agro-industrial byproducts/wastes to enable efficient sorting for various agro-industrial applications. Bioresources and Bioprocessing, 11(1), 45. https://doi.org/10.1186/s40643-024-00763-7

Purbowati E, Adiwinarti R, Rianto E, Arifin M, Purnomoadi A and Restitrisnani V 2025 The effect of using agricultural industrial waste to replace grass on the efficiency of sustainable lamb production. 37. https://www.lrrd.org/lrrd37/4/3760rest.html

Supriyati, Krisnan R, Budiarsana I G M and Praharani L 2016 Effect of different protein and energy levels in concentrate diets on nutrient intake and milk yield of Saanen x Etawah Grade goats. Jurnal Ilmu Ternak Dan Veteriner, 21(2), 88-95. https://doi.org/10.14334/jitv.v21i2.1356

Tillman AD, Hartadi H, Reksohadiprodjo S, Prawirokusumo S and Lebdosoekodjo S 1984 Ilmu Makanan Ternak Dasar. Gadjah Mada University Press.

Umroni A, Rianawati H, Rahayu A A D, Krisnawati, Leksono B and Paradhipta D H V 2024 Chemical Compositions and Plant Secondary Metabolites of Nyamplung (Calophyllum inophyllum L) Oilseed Press-cake from Different Locations. IOP Conference Series: Earth and Environmental Science, 1360, 012001. https://doi.org/10.1088/1755-1315/1360/1/012001

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for Dietary Fiber, Neutral Detergent Fiber and Nonstarch Polysaccharides in Relation to Animal Nutrition. Journal of Dairy Science, 74(10), 3583-3597. https://doi.org/10.3168/jds.S0022-0302(91)78551-2

Vicente S L A, Nogueira D M, Voltolini T V, Yamamoto S M, Lopes Júnior E S e Moraes, S A 2020 Avaliação on-farm dos níveis de energia na dieta sobre a produção e a composição físico-química de leite de cabras. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 72(4), 1424-1432. https://doi.org/10.1590/1678-4162-11357

Weimer P J 2022 Degradation of Cellulose and Hemicellulose by Ruminal Microorganisms. Microorganisms, 10(12), 2345. https://doi.org/10.3390/microorganisms10122345

Wu G 2022 Nutrition and Metabolism: Foundations for Animal Growth, Development, Reproduction and Health. In G. Wu (Ed.), Recent Advances in Animal Nutrition and Metabolism (Vol. 1354, pp. 1-24). Springer International Publishing. https://doi.org/10.1007/978-3-030-85686-1_1