Evaluation of giving complete wafers containing lamtoro leaves-cassava leaves to sheep

Mahirah Firdaus, Yuli Retnani and Didid Diapari

¹ Department of Nutrition and Feed Technology, Faculty of Animal Science, IPB University, Bogor 16680, Indonesia
yuli_retnai@apps.ipb.ac.id

Abstract

Legumes and agricultural waste can be used as substitutes for forage. An example of Leguminosae is lamtoro leaves, and an example of agricultural waste is cassava leaves. This study aimed to evaluate the quality of wafer feed containing lamtoro leaves-cassava leaves by feeding wafers with different percentages. This research used five treatments with four replications. The treatments given were WF = conventional feed (forage), WF25 = conventional feed + 25% wafer feed, WF50 = conventional feed + 50% wafer feed, WF75 = conventional feed + 75% wafer feed, WF100 = 100% wafer feed. Data were analysed using ANOVA and Duncan's test. Based on the physical quality, as seen from the water content, water activity, density, and durability, the wafer feed has better quality. This experiment showed that feed treatments affected (p<0.05) consumption feed, body weight gain, and feed efficiency. This research indicates that giving wafer feed will increase the consumption of nutrients DM, CP, CF and EE in sheep feed. The best result of body weight gain is that feeding wafers is treated by WF100 with the value of 116,74 g head^-1day^-1. The best result of feed efficiency and IOFC from this research is that WF100 trades feeding wafers with a value of 13,37 % for feed efficiency and Rp. 395.583 for IOFC.

Keywords: feed wafers, nutrient quality, physical quality, sheep performance

Introduction

Livestock in Indonesia, especially local farms, generally carry out traditional breeding activities by providing forage in the form of forage. This also happened at the research location in Cinangka Village, which has a habit of feeding with forage. The fluctuating forage availability makes it difficult for farmers to obtain forage continuously. In the dry season, ruminants, especially goats, consume the driest natural grass (standing hay) with quality and quantity that has yet to be fulfilled. As a result, there is a decrease in livestock productivity due to a need for adequate nutrition in the feed given (Paga et al 2008). Substitution of other sources of feed raw materials is a way to meet feed needs. Forage substitution can come from legumes and agricultural waste. One of the potentials for leguminosae and agricultural waste that has yet to be utilised optimally, especially in Cinangka Village, is lamtoro and cassava leaves.

Substitution of raw materials is one way of fulfilling feed. Substitution for the use of grass substitutes as forage can come from agricultural waste and legumes. Leguminous that can be used is in the form of lamtoro. Lamtoro has a protein content of up to 24.4% (Paga et al 2008), so it can increase livestock productivity and has high palatability. Lamtoro leaves alone can produce as much as 8.1 tons of BK/ha (Nulik et al 2004). In lamtoro leaves, paying attention to its use in livestock is necessary because it contains an anti-nutritional substance, namely mimosine. Mimosin levels in lamtoro are 7.19% (Argadyasto et al 2015).

Cassava leaves are rich in crude protein (CP), which is 29-36% (Hermanto and Fitriani 2018). Cassava leaves are one of the many plants found in Indonesia. The part of cassava leaves that can be used as animal feed is the old part of the leaf that can no longer be used as food. The Ministry of Agriculture (2019) noted that the harvested area of cassava plants in Indonesia in 2018 reached 792,952 ha, with cassava leaf production reaching 0.92 tons/ha/year of dry matter (Lebdosukoyo 1983). The availability of cassava leaves in Indonesia is 729,516 tonnes/year. The high production of cassava leaves has yet to be used optimally as animal feed. Cassava leaves are identified as a source of protein, minerals and vitamins. In addition, cassava leaves have a high energy content in the rumen which is easy to degrade and acts as a protein by-pass (Fasae and Yusuf 2022). However, hydrocyanic acid (HCN) and tannins' high content limit cassava leaf use in animal feed (Soto-Blanco and Górniak 2010).

The presence of anti-nutritional substances in lamtoro leaves and cassava leaves is necessary to process feed to reduce these anti-nutrients so that they are safe to be given to livestock. Processing that can be done is in the form of wafer processing. According to Retnani et al (2020), feeding in wafers can increase nutrient consumption and body weight in livestock. Cinangka Village has the potential to substitute feed ingredients and feed processing. In the previous research, the exploration of agricultural waste feed raw materials in Cinangka Village was also carried out and processed into silage and wafers. The best results of earlier research, namely processing in the form of wafers with raw materials of lamtoro leaves and cassava leaves, have a higher CP nutrient content and have a good effect on livestock performance.

Application of feed processing technology can be used to produce ruminant feed that is durable, easy to handle, easy to distribute, easy to give to livestock, and available throughout the season. Feeding is done with different percentages to see the results with the best percentage of wafer feeding. In this study, the measurement of feed quality was carried out to see the physical quality of the feed and the effect it had on the physiological condition of livestock, nutrient consumption, and performance in livestock. Physical tests on wafer feed can be carried out, are water content, water activity, specific gravity, and impact resistance tests. Performance parameters in livestock measured in this study were daily body weight gain (ADG), feed efficiency, and Income Over Feed Cost (IOFC).

Substitution of feed ingredients and processing feed ingredients are several solutions for providing feed, especially during the dry season. However, with the use of lamtoro leaves and cassava leaves, which are processed into wafer feed, it is not known what percentage of the best feed is given to livestock that is used for foraging feed. Therefore, it is necessary to provide wafer feed with different percentages to determine the effect of livestock used to being given forage feed. In addition, physical testing was carried out on the wafer feed to determine the physical quality, which represents the quality of feed on wafer feed.

The purpose of this study was to identify the physical quality and nutrient quality of wafer feed containing lamtoro leaves and cassava leaves and evaluate the effectiveness of substitution of lamtoro-cassava leaf feed ingredients and wafer feed processing on performance in livestock.

Materials and methods

Ethical approval

The experiment had been approved by Faculty of Animal Science, Bogor Agricultural University, Indonesia and followed the protocol for handling and care of animals, according to the IPB University Animal Ethics Committee.

Feed processing

The feed formulation in this study was based on Kearl (1982) for sheep with a body weight of 20 kg and a body weight gain of 150 g head ^-1 day^-1. The formulation was carried out using a trial-and-error method. The composition of feed ingredients and nutritional content during the study is shown in the following table.

The forages used in this study were field grass (Megathyrsus maximus), odot grass (Pennisetum purpureum cv. Mott), elephant grass (Pennisetum purpureum). Feed production is carried out based on the feed formulation that has been selected to become wafer-shaped feed. Wafer feed production process through grinding, mixing, pressing and heating with a temperature of 120°C for 10 minutes. The process of making complete feed uses lamtoro leaves, and cassava leaves as the main substitution ingredients. Feed production is carried out based on the formulation in Table 1. Lamtoro leaves, and cassava leaves are processed through chopping, drying and grinding. Next, all the ingredients are mixed according to the formulation (Table 1) with a mixer machine. After mixing, feed will be produced on wafer machine with a temperature of 120°C for 10 minutes.

Animals and experimental design

A total of 20 rams with an average body weight of 20 kg were randomly given 5 different feed processing treatments, namely WF: Forage, WF25: forage+ 25% wafer feed, WF50: forage+ 50% wafer feed, WF75: forage+ 75% wafer feed, WF100: wafer feed consisting of 4 replicates with one tail per repetition. Sheep are kept in individual pens. The feed given consisted of forage and feed wafers according to the presentation in each treatment. Every day the sheep are given food in the morning and evening with drinking water given ad libitum. The composition and nutrient content of the research feed can be seen in Table 1. Sheep were kept in individual pens for 2 months carrying out a feed adaptation period for the first 1 week. Prior to the adaptation period, 2 mL of Albendazole was administered orally to each lamb to minimize disease due to worm infection. The remaining feed from each treatment will be weighed every day by separating the forage and feed wafers.

Sampling and measurements

Feed wafers are subjected to physical tests to see the physical quality of the feed and to test the nutrient content. The physical tests included moisture content using the Grain Moisture Tester PM-650, water activity type Rotronic HWF503-AW-A-SET-40, and specific gravity using the Lopez et al (1996), namely dividing the weight of the feed (g) by the change in volume of distilled water (L) and chemical testing was carried out to determine the nutrient content of the feed according to the standard method of the Association of Official Analytical Chemists (AOAC 2005). Evaluation of sheep performance is measured through, consumption of feed nutrients, and livestock performance. Consumption of nutrient feed is calculated based on consumption of feed with nutrient content in it. Measurement of nutrient consumption consists of dry matter (DMI), crude protein (CP), ether extract (EE), crude fiber (CF) and nitrogen-free extract (NFE). Livestock performance includes body weight gain, feed efficiency, and IOFC (Income Over Feed Cost). The sheep’s average body weight gain (ADG) is done every 2 weeks to determine body weight gain. Efficiency values are obtained from feed consumption and body weight gain during rearing. The IOFC value is calculated to determine the profit obtained after the rearing process, based on the sheep's buying and selling prices and the cost of feed during the study period. Buying and selling prices for sheep are obtained from prices in effect in June 2022 at the Bogor market, West Java, Indonesia.

Statistical analysis

Data obtained from this study were analysed using ANOVA (analysis of variance) through SPSS v 20.0, and the significantly different data among treatment groups were determined by using the Duncan's Multiple Range Test (DMRT) and considered at p<0.05.

Results and discussion

Influence of Physical Properties

The physical characteristics of the feed are closely related to the quality of the feed. In addition, the characteristics of the feed are closely related to how to handle the feed. The physical characteristics of the feed are shown in Table 3.

The water content in the feed can affect the storage of the feed, so it is necessary to measure the water content and water activity to determine the water content in a feed. The wafer water content in this study was 9.39 ± 0.08%. The average value of this water content, when compared to the Indonesian National Standard (2016) of 14%, is still below the maximum and safe limit for feed storage. Wafer water activity in this study was 0.61 ± 0.02. The water activity levels obtained are susceptible to exposure to microbes in storage without proper handling. This is in accordance with Kayadoe et al (2020) that the water activity value is 0.6-0.7 indicating that mould growth can occur. Each microbe has a minimum limit for growth, so as a prevention it requires handling in packaging and feed storage locations. Specific gravity values are known to see the density of a feed (Khalil 1999). Mixing feed ingredients with different shapes and particle sizes can affect the value of specific gravity.

The value of the wafer-specific gravity in this study was 1.28 ± 0.12 g mL-1. According to (Yana et al 2018), wafers that have a high specific gravity will result in increased space capacity. Factors that affect the specific gravity because there is a considerable difference between the particles making up the wafer. According to Salam (2017), materials with the same particle size or not greatly affect the value of the specific gravity of the wafer, by mixing the same particle size the two materials used can bind each other well so that the specific gravity value is high. According to (Mustafa et al 2022) that the ratio consists of particles that have a large difference in specific gravity, the mixture will be unstable and tends to separate easily again. Impact resistance is important to determine the resistance of wafers during the transportation process so that the wafers are not damaged during transit. The impact resistance of the wafer feed in this research is 95.92 ± 1.71%. According to Syahri et al (2018), the best wafer physical properties have an impact resistance value of 94.45%. Based on the literature, the impact resistance of the wafers made is good. Impact resistance is closely related to density, where a high density means that the particle cavities will get smaller and will be more resistant to impact, another thing that also influences the manufacturing process and manufacturing standards (Jaelani et al 2016).

Effect of treatment on nutrient consumption

The results showed a very significant effect of the feed given on dry matter consumption, consumption of crude protein, consumption of crude fat, consumption of crude fiber, consumption of BETN, and consumption of TDN (p<0.05).

The forages used in this study were field grass (Megathyrsus maximus), odot grass (Pennisetum purpureum cv. Mott), elephant grass (Pennisetum purpureum). In this study, the results of DM consumption during the maintenance period were significantly different (p<0.05) based on the results of the ANOVA test for all treatments given. The research shows that giving wafers with different percentages affects dry matter consumption at each addition. The highest DM consumption was in the WF100 treatment (100% wafer feeding) which was 962.14 ± 2.14 g tail-1 day-1. The high consumption of DM in the treatment of 100% wafer feed (WF100) was due to the DM content of wafer feed being higher than the DM content in the other treatments. Consumption of CP nutrients obtained in this study based on the ANOVA test was significantly different (p<0.05). CP consumption in the feeding treatment in the wafer addition treatment met the needs based on the needs of Kearl (1982), which required 72.86-105.10 g tail-1 day-1. However, in the control feeding treatment, namely conventional feed (WF), CP consumption has not been achieved according to the needs of Kearl (1982). The CP requirement was not met because the CP content in the control treatment was lower than the PK content in the other treatments. Tarmidi (2004) stated that the low consumption of dry matter caused the shortage of crude protein. The crude protein consumption in this study was directly proportional to the dry matter consumption. The higher consumption of CP can be caused by giving wafers with different percentages so that the nutrients contained are also different.

Consumption of EE nutrients also had significant differences (p<0.05) based on statistical analysis between treatments such as DM consumption and CP. The lowest EE consumption was in the control feed which was very different from the other treatments. The nutrient content in each different treatment affects the consumption of nutrients in livestock. The results of the consumption of crude fat in the feeding treatment were in accordance with the opinion of Jayanegara et al (2017) which stated that the consumption requirement for EE of local rams ranged from 6-120 g head-1 day-1, but in the control treatment it was still below this requirement. Consumption of crude fiber in Table. 4 showed significantly different results (p<0.05) between the treatments based on statistical tests. CF nutrient consumption is also influenced by the nutrients eaten by livestock. The treatment of feeding 100% wafer feed (WF100) showed a higher CF consumption value, this was influenced by the nutrient content of DM which was also higher than the others. The need for crude fiber in sheep according to Parakkasi (1999) is between 12-14% of the dry matter consumption of the ration.

The consumption of BETN (Nitrogen-Free Extract Material) had a significantly different effect (P<0.05) on the treatment given. in Table. 4 shows that the more the percentage of wafers fed, the higher the consumption of BETN in livestock. According to Parakkasi (1999) the BETN needed by local sheep is between 39% -94% of BK consumption. The study’s results obtained 49-65% of the consumption of BK so that it can be stated that the consumption of BETN during the study met the needs of the sheep. After being tested through statistical tests, TDN consumption was significantly different (p<0.05) to the treatment given. The TDN consumed by the study sheep was 191.70 – 728.66 g head-1 day-1. So that the WF treatment (conventional feeding) was not in accordance with NRC (2006) but other treatments or those given the addition of feed wafers were appropriate, namely 200 - 600 for sheep weighing 10-20 kg. Based on Table. 4 it can be seen that the greater the increase in wafer feed, the greater the consumption of TDN so that the greater the energy intake used for basic living needs and growth. The higher the TDN value of the feed, the better the feed quality consumed because the more nutrients can be digested.

Effect of treatment on performance

Livestock performance can be measured in several ways: body weight, Daily Body Weight Gain, feed efficiency, and IOFC. The following is a table showing information regarding performance in livestock.

Figure 1. Effect of feeding treatments on Average Daily Weight

Based on the results in Table. 4 shows that the highest PBB (Body Weight Gain) is in the treatment of 100% wafer feed (WF100). Daily Body Weight Gain in this study ranged from -18.08 to 116.74 g of tail-1 day-1. ADG in this study was higher than the results of Tanuwiria's study (2013) ranging from 49-88 g of tail-1 day-1. The WF treatment (conventional feeding) PBBH obtained minus because there was no increase in body weight in this treatment. It can be seen that feeding only with forage cannot meet the nutritional needs of livestock to be able to grow. The forages used in this study were field grass (Megathyrsus maximus), odot grass (Pennisetum purpureum cv. Mott), elephant grass (Pennisetum purpureum). Table. 4 It is also known that the more concentration of wafer form feeding, the greater the PBBH obtained. The increase in body weight is influenced by the feed nutrients contained in the feed consumed.

Based on Table. The 4 highest efficiency was in the treatment of 100% wafer feed (WF100) with a value of 13.37%. Wafers are able to have high efficiency because they have a high dry matter content so they can increase body weight quite high with a small amount of excess consumption. The level of consumption of dry matter can affect the supply of other nutrients so as to meet the basic needs of livestock (Mathius et al. 2002). The research results must influence livestock so that it is necessary to calculate profits to see opportunities for research development in the business sector. Income over feed cost (IOFC) is an economic analysis used to calculate the economic benefits obtained from the results of calculating income minus the cost of feed during livestock raising. According to Setyowati (2005) livestock with low feed consumption but able to increase body weight can be able to generate large income. Based on the results of the data in Table. 5 it was found that the treatment that produced the greatest profit was the feed treatment of 100% wafer feed (WF100). The highest IOFC value is in the wafer treatment (WF100) because it has high feed efficiency so that a little feed can significantly increase the body weight of the sheep (Ulfa et al. 2019). IOFC has proven that the 100% wafer feed (WF100) treatment is more beneficial than other feeding treatments.

Conclusion

• Wafer feed contains nutrients in the form of DM, CP, CF, EE, BETN, TDN which is higher than conventional feed.
  
  
• The in vivo test results based on statistical tests showed that the optimum ADG was in the WF75 treatment (conventional feed + 75% wafer feed) with a value of 105.80 g tail-1 day-1.
  
  
• The value of feed efficiency in the WF50 treatment (conventional feed + 25% wafer feed) was significantly different with a value of 7.40%. Followed by the highest IOFC value in the WF100 treatment (wafer feeding) with a value of Rp. 395,583.

Acknowledgement

The author thanks the LPDP Scientific Research, which has provided funding for this research by the Agreement/Contract Number: 052/E4.1/AK.04.RA/2021

References

AOAC 2005 Official methods of analyses (17th ed.). Washington (US): Association of Official Analytical Chemists.

Argadyasto D, Retnani Y, Diapari D 2015 Pengolahan Daun Lamtoro Secara Fisik Dengan Bentuk Mash, Pellet dan Wafer terhadap Performa Domba. Buletin Makanan Ternak.102(1): 19-26

Fasae O A, Yusuf A O 2022 Cassava leaves and peels: Nutritional value and potential productivity in West African dwarf breeds of sheep and goats– A review. Niger J Anim Prod. 49(3):305–315. doi: 10.51791/njap.v49i3.3562

Hermanto dan Fitriani 2018 Pengaruh Lama Proses Fermentasi Terhadap Kadar Asam Sianida (HCN) dan Kadar Protein pada Kulit dan Daun Singkong. JRTI. 12(2):10-22.

Irawan A, M Hartono, AK Wijaya, S Suharyati 2022Pengaruh suplementasi tepung krokot (Portulaca oleracea) terhadap sel darah merah, hemoglobin, dan packed cell volume pada kambing jawarandu (Capra aegagrus hircus). JRIP. 6(1): 37-43.

Jaelani A, Dharmawati S, Wacahyono 2016 Pengaruh tumpukan dan lama masa simpan pakan pelet terhadap kualitas fisik . Ziraa’Ah. 41(2):261–268.

Jayanegara A, Ridla M, Astuti D A, Wiryawan K G, Laconi E B, Nahrowi 2017 Determination of energy and protein requirements of sheep in Indonesia using a meta-analytical approach. Media Peternak. 40(2):118–127. doi:10.5398/medpet.2017.40.2.118.

Kayadoe M, Sinaga S, Rochana A, Tanuwiria U H 2020 Kajian Kualitas Fisik Ransum Pelet dalam Upaya Rekayasa Ransum Bagi Kuskus Bertotol Biasa. J Sain Peternak Indones. 15(1):7–17. doi:10.31186/jspi.id.15.1.7-17.

Kearl L C 1982 Nutrient requirements of ruminants in developing countries. International feedstuffs institute Utah agriculture experiment station. Utah (US): Utah State University.

Kementrian Pertanian 2019 Luas Panen Ubi Kayu Menurut Provinsi. Kementrian Pertanian.

Khalil 1999 Pengaruh kandungan air dan ukuran partikel terhadap perubahan perilaku sifat fisik bahan pakan lokal. Media Peternakan. 22(1):33-42

Lebdosukoyo S 1983 Pemanfaatan limbah pertanian untuk menunjang kebutuhan pakan ruminansia. Pertemuan Ilmiah Ruminansia Besar. Bogor (ID): Puslitbang Peternakan.

Lopez G, G Ros, F Rincon, M J Periago, M C Martinez, J Ortuno 1996 Relationship between physical and hydration properties of soluble and insoluble fiber of artichoke.J.Agric. Food Chem. 44: 2773-2778

Mathius I-W, Gaga I B, Sutama I-K 2002 Kebutuhan Kambing PE Jantan Muda akan Energi dan Protein Kasar. J Ilmu Ternak dan Vet. 7(2):99–109.

Mustafa H K, Zamhir R, Widyastuti R M, Susilawati I 2022 Inovasi Pengawetan Berbentuk Wafer Dari Campuran Turiang Padi Dan Legum Gamal Sebagai Pakan Ruminansia. J Nutr Ternak Trop dan Ilmu Pakan. 3(3):87–94. doi:10.24198/jnttip.v3i3.37408.

Nathalie H, Bourge`s-Abella, BS Reynolds, AGeffre´, J-P Braun, C Trumel 2009 Validation of the medonic CA620/530 Vet 20-ml microcapillary sampler system for hematology testing of feline blood. J Vet Diagn Invest. 2: (364-368). doi: 10.1177/104063870902100311

Nulik J, DK Hau PTh Fernandez, S Ratnawati 2004 Adaptasi beberapa Leucaena species di Pulau Timor dan Sumba, Nusa Tenggara Timur. Hlm 825-831. Prosiding Seminar Nasional Teknologi Peternakan dan Veteriner Bogor. 2004 Augt 4-5. Pusat Penelitian dan Pengembangan Peternakan, Bogor.

NRC 2006 Nutrient Requirement Of Small Ruminant: Sheep, Goats, Cervids, And New World Camelids. Washington (US): Natl Academy Pr.

Retnani Y, NN Barkah, A Saenab, Taryati 2020 Teknologi Pengolahan Wafer Pakan untuk Meningkatkan Produksi dan Efisiensi Pakan. Wartazoa. 30(1): 37-50.

Retnani Y, H A Sukria, I Wijayanti, D Diapari, M D Erlangga, M F Ibsyah, Taryati, N N Barkah, N Qomariyah 2023 Sheep Performance on Valuable Silage and Wafer from Agricultural Waste. 11(3) : 417-423.

Paga A, B Bernadete, N Theresia 2008 Pemanfaatan Wafer Leguminosa sebagai Pakan Alternatif Ternak Kambing di Daerah Lahan Kering. Partner. 2(15): 185-191.

Parakkasi A 1999 Ilmu nutrisi dan makanan ternak ruminansia. Jakarta (ID) : Universitas Indonesia Press.

Salam R M 2017 Sifat fisik wafer dari bahan baku lokal sebagai bahan pakan ternak ruminansia.. J Ilm Peternak. 5(2):108–114.

Sastradipradja D, SHS Sikar, R Widjayakusuma, A Maad, T Unandar, H Nasution, R Suriawinata, K Hamzah 1989 Penuntun Praktikum Fisiologi Veteriner. Bogor (ID): Pusat Antar Universitas IlmuHayati.

Setyowati A 2005 Pengaruh limbah mediaproduksi jamur pelapuk kayu isolat HS terhadap konsumsi, produksi dan efisiensi pakan pada ternak domba[skripsi]. Bogor(ID): Institut Pertanian.

Soto-Blanco B dan Górniak S L 2010 Toxic Effects Of Prolonged Administration Of Leaves Of Cassava (Manihot esculenta Crantz) to Goats. Exp Toxicol Pathol. 62(4):361–366.

Syahri M, Retnani Y, Khotijah L 2018 Evaluasi Penambahan Binder Berbeda Terhadap Kualitas Fisik Mineral Wafer. Bul Makanan Ternak. 16(1):24–35.

Tarmidi A R 2004 Pengaruh pemberian pakan yang mengandung ampas tebu hasil biokonversi oleh jarum tiram putih (Pleurotus ostreatus) terhadap performa domba priangan. JITV. 9(3): 157-163.

Tanuwiria U H 2013Efek suplementasi kompleks mineral-minyak dan mineralorganik dalam ransum terhadap kecernaan ransum, populasi mikroba rumen dan performa produksi domba jantan. Seminar Nasionaldan Kongres Asosiasi Ahli Nutrisi dan Pakan Ternak Indonesia 2007 Juli 27; Yogyakarta, Indonesia. Yogyakarta (ID): Fakultas Peternakan Universitas Gadjah Mada. Hlm 327-334.

Trisyulianti E, Suryahadi, Rakhma V 2003 Pengaruh penggunaan molases dan tepung gaplek sebagai bahan perekat terhadap sifat fisik wafer ransum komplit. Med Pet. 26(1): 35-40.

Ulfa E M, Ali U, Muwakhid B 2019Pengaruh Penggunaan Daun Kaliandra Merah (Calliandra calothyrsus) dalam Complete Feed untuk Penggemukan Domba Ekor Gemuk. J Rekasatwa Peternak. 1(1):6–13.

Winarno FG, S Fardiaz, D Fardiaz 1980 Pengantar Teknologi Pangan. Jakarta (ID): Gajah Mada University Press

Yana S, Ziriful, Priambudiman Y, Panjaitan I 2018 Karakteristik fisik pakan wafer berbasis bungkil inti sawit. Di dalam: Beni Hidayat, editor. Seminar Nasional Pengembangan Teknologi Pertanian; 2016 Okt 08; Lampung, Indononesia. Lampung (ID): UP Politeknik Negeri Lampung. Hlm 401-404.