Feeding Selenium-rich Fermented Palm Kernel Cake to Laying Hens (B. Sundu et al,) 37 J I T A A Journal of the Indonesian Tropical Animal Agriculture Accredited by Ditjen Riset, Teknologi dan Pengabdian kepada Masyarakat No. 164/E/KPT/2021 J. Indonesian Trop. Anim. Agric. pISSN 2087-8273 eISSN 2460-6278 http://ejournal.undip.ac.id/index.php/jitaa 48(1):37-46, March 2023 DOI: 10.14710/jitaa.48.1. 37- 46 Feeding selenium-rich fermented palm kernel cake to laying hens produces selenium-rich eggs, increases egg production and quality B. Sundu*, Hafsah, M. Pamulu, A. Adjis, U. Hatta, E. Kala’langi, G. Sapu, S. Arifuddin, Damry, and I.G. Putra Faculty of Animal Husbandry and Fisheries, Tadulako University, Palu, Central Sulawesi. *Corresponding e-mail: b_sundu@yahoo.com Received August 24, 2022; Accepted February 06, 2023 ABSTRACT A study was conducted to determine the effect of selenium (sodium selenite) added to palm kernel cake (PKC) before fermentation on production, selenium content, and quality of eggs. The PKC was added with 0.1% sodium selenite and 1% baking yeast (Fermipan®). The mixture was added with ster- ile distilled water to increase the water content of the substrate. The substrates were fermented at room temperature for 5 days. The fermented products of selenium-rich fermented palm kernel cake (SRFPKC) were dried and fed to the laying hens. The experimental diets used were T-0: without SRF- PKC, T-1: 0.25% SRFPKC, T-2: 0.50% SRFPKC, T-3: 0.75% SRFPKC and T-4: 1.0 % SRFPKC. The diets were given to 180 laying hens aged 22 weeks for 14 weeks. Data on egg production, feed intake and feed conversion ratio were recorded. Feed digestibilities of dry matter and protein were measured based on the method of total fecal collection. Egg qualities and egg weight loss were done using eggs stored for 1 and 30 days. Selenium and cholesterol contents of eggs were also measured. This study used a completely randomized design and was analyzed by analysis of variance. The results showed that the addition of SRFPKC increased egg production, hen day, egg weight, egg selenium, feed digest- ibility, improve FCR (P<0.05) and inhibit the process of decreasing the quality and weight of eggs stored for 30 days (P<0.05). In conclusion, the addition of SRFPKC increased egg production, feed digestibility, and egg selenium, improve FCR and slow down the deterioration of egg quality stored for 30 days. Keywords: Egg production, Fermentation, Palm kernel cake, Selenium, Yeast INTRODUCTION Covid 19 has attacked more than 200 coun- tries with more than 44 million deaths (WHO, 2020). The world health organization (WHO) stated that the SARS Cov-2 virus will remain for a long time, therefore a healthy lifestyle, both in terms of avoiding contact with viruses and con- suming functional foods, should be sought to prevent the disease. One of the functional nutri- ents that can play a role in the formation of the body's immune system is the mineral selenium (Se). This trace mineral has various health func- tions, including preventing infection and disease caused by viruses (Beck et al., 2003), as an anti- oxidant in the form of Glutathione peroxidase mailto:b_sundu@yahoo.com 38 J. Indonesian Trop. Anim. Agric. 48(1):37-46, March 2023 (GSH-Px) (Cai et al., 2019), can prevent cancer (Chen et al., 2013), prevent heart disease (Flores -Mateo et al., 2006), increase immunity (Huang et al., 2012), and increase sperm fertility (Ahsan et al., 2014). This mineral can also inhibit viral mutations causing viruses to become more viru- lent (Beck et al., 2003). The emergence of sever- al relatively virulent variants of the Covid 19 virus indicates that the SARS Cov-2 virus con- tinues to mutate and the prevention process can be carried out by giving Se. Zhang et al. (2020) reported that there was a correlation between the healing of Covid-19 disease and the Se content of hair in the cases in China. The efficacy of Se in promoting growth, production, and modulating the immune system of poultry has been well accepted. An increased egg production (Liu et al., 2020), maintained egg quality during storage (Hatta et al., 2020) and increased sperm fertility (Ahsan et al., 2014) are some positive effects of Se for laying hens, along with its beneficial property in improving the health status of poultry (Surai, 2006). Therefore, feeding the selenium-rich feed to the laying hens can not only increase the production, egg quality, and health of chickens but at the same time can also produce selenium-rich eggs that are benefi- cial to humans, especially in the current Covid- 19 pandemic era. Studies on the production of selenium-rich coconut meal for broiler chicken through the bioconversion process of inorganic Se into or- ganic have been done by a number of workers (Sundu et al., 2019; Mozin et al., 2019). Howev- er, data on the use of baking yeast Saccharomy- ces cerevisiae to bio-convert toxic sodium sele- nite into organic Se by using palm kernel cake as the solid media and its effect on egg production and the quality of 30 days of storage have not been available. A study was carried out to deter- mine the effect of feeding selenium-rich fer- mented palm kernel cake on feed intake, FCR, feed digestibility, egg production, egg quality, selenium-rich egg, and egg cholesterol. MATERIALS AND METHODS Preparation of Substrate and Fermentation Process Palm kernel cake (PKC) was used as a sub- strate and baking yeast Saccharomyces cere- visiae (Fermipan®) as a starter or equivalent to Table 1. Basal diet Feed ingredients Concentration (%) Soybean meal 16.2 Corn 52.0 Fish meal 8.0 Rice bran 11.0 Palm kernel cake 10.0 Calcium Carbonate 3.0 Dicalcium phosphate 1.0 Table salt 0.3 Premixes 0.3 Methionine 0.1 Lysine 0.1 Calculated nutrients Crude protein (%) 17.9 Metabolizable energy (kcal/kg) 2741 Calcium (%) 2.00 Phosphorus (%) 0.62 Selenium (%) 0.21 Methionine (%) 0.47 Lysine (%) 1.07 Feeding Selenium-rich Fermented Palm Kernel Cake to Laying Hens (B. Sundu et al,) 39 346 CFU/g. Palm kernel cake was finely ground. The fermentation method on solid media (Sundu et al., 2019) was used in this study. The fine ground substrate was autoclaved for 20 minutes at a pressure of 20 psi and then cooled to room temperature. The substrate was mixed with 0.1% sodium selenite and then incubated with 1% bak- ing yeast (Fermipan®) and added with sterile distilled water to produce 80% moisture content. The mixture was placed into a plastic that has been perforated with a needle. Substrates were stored for 5 days at room temperature. On day 5, the substrate was harvested and dried in an oven at 60 o C for 24 hours. The fermentation products were analyzed for proximate fractions (AOAC, 1990), selenium content (Almeida et al., 2015), and cholesterol using the Liebermann Burchard method (Kleiner and Dotti, 1962). Animals and Cages The protocol of the study has been approved by the animal ethics committee of the Faculty of Animal Husbandry and Fisheries, Tadulako Uni- versity with the approval number: 35/ AEC/5/2021. The study used a total of three hun- dred 20-weeks-old laying hens. The laying hens were kept in the individual battery pens for 14 weeks. Prior to the data collection, vaccination against New Castle Disease was done a week after the arrival of the hens and was repeated after three months. Two weeks of adaptation pe- riod was carried out to accustom the hens to the pen and to select the hens based on two weeks of egg production was done. A total of 180 selected hens were used for research. The selection was based on the initial egg production. The feeder was located outside of the front pen. Nipple- shaped drinker was placed above the pen. The pen and the surroundings of the experimental house were cleaned and disinfected whenever necessary. Experimental Diets An experimental basal diet (Table 1) was formulated using the UFFF software (Pesti et al., 1986). All the feed ingredients were locally pur- chased at a poultry shop. Diets mixture was done every two weeks to maintain the freshness of the diet. The treatment diets were arranged according to the increasing levels of Se in the diets by sup- plementing Se-rich fermented palm kernel cake (SRFPKC). All the treatments are presented in Table 2. Parameters and Data Analysis The productive performance parameters measured were: egg production (egg weight, total production, and hen day production), feed intake, feed conversion ratio (FCR), digestibilities of dry matter, and protein, excreta dry matter, egg yolk index, Haugh unit (HU), percentages of yolk, albumen and shell, the thickness of the shell, yolk color, and egg weight loss after storage of 1 and 30 days. Selenium content was analyzed by using the procedure of Almeida et al. (2015) and Liebermann and Burchard method was used to measure the cholesterol content of the meat (Kleiner and Dotti, 1962). The HU, the egg yolk index and egg weight loss are measured based on the following formula: Table 2. Experimental diets Treatments Selenium (ppm) Replication Hens Basal 0.21 6 6 Basal + 0.25% SRFPKC 0.87 6 6 Basal + 0.50% SRFPKC 1.53 6 6 Basal + 0.75% SRFPKC 2.20 6 6 Basal + 1.00% SRFPKC 2.86 6 6 SRFPKC: selenium-rich fermented PKC containing 265 ppm of selenium and untreated PKC contains 0.186 ppm selenium Egg weight loss (%) = egg weight on collection day – egg weight on measurement day X 100 egg weight on collection day 40 J. Indonesian Trop. Anim. Agric. 48(1):37-46, March 2023 HU= 100*Log (h+7.57) – (1.7 * W 0.37) Where h: albumen height and W: egg wight Egg yolk index = Yolk height / yolk diameter This study used a completely randomized design with 5 treatments and 6 replications (Steel and Torrie, 1980). Data were analyzed by the variance analysis. Any differences detected by the analysis of variance were further tested by the Tukey test. RESULTS AND DISCUSSION The effect of treatment on egg production, feed consumption, FCR, dry matter (DM) of ex- creta, DM digestibility, protein digestibility, egg selenium, and egg cholesterol can be seen in Ta- ble 3. Effect of treatment on egg shape index, egg weight loss, percentage of yolk, albumen and eggshell, albumen and yolk profiles, and shell thickness of eggs stored for 1 day and 30 days at room temperature are shown in Tables 4 and 5. The treatment had a significant effect (P<0.05) on egg production, hen day production, egg weight, FCR, dry matter digestibility, and egg selenium, but the treatment did not have a significant effect (P>0.05) on feed consumption, excreta dry matter and egg cholesterol content (Table 3). The effect of treatment on eggs stored for 1 day on all egg quality parameters had no significant effect (P>0.05). Storage of eggs for 30 days reduces egg quality, but eggs produced from hens fed a diet containing Se-rich ferment- ed PKC (SRFPKC) can slow down the process of decreasing egg quality (albumen height, Haugh unit, yolk height, and yolk index), and decreased egg weight loss during storage (P<0.05). Egg index, percentage of yolk, albu- men and eggshell, shell thickness, and yolk color were not affected (P>0.05) by the addition of SRFPKC. Sodium selenite contains 45.7% selenium, adding 0.1% of this compound to the palm ker- nel cake (PKC) before fermentation, mathemati- cally, can increase the Se concentration of the PKC to 457 ppm. The fermentation process of PKC for 5 days with S. cerevisiae can only pro- duce 265 ppm selenium. This means that 58% of the Se added to the PKC before fermentation remained in the PKC or may have turned into yeast Se, while 42% of the Se was lost during the fermentation process. This loss may indicate that yeast metabolizes inorganic Se through the selenite methylation process which can produce hydrogen selenite as a waste product and gase- ous product which is released freely into the air. The very strong and toxic odor smelled in this study can be an indicator of the production of hydrogen selenite during the fermentation pro- cess and this also indicates that there is a bio- conversion process of inorganic Se into Se pro- tein, either seleno-cysteine or seleno- methionine. According to Demirci et al. (1999), about 0.3% of Se can be converted to seleno- methionine by the yeast S. cerevisiae. The high- er content of Se contained in the fermentation process with the addition of sodium selenite than the findings of Demirci et al. (1999) may indi- cate that some of the Se present in fermented PKC were still in inorganic form. Studies on the effect of the addition of Se in poultry feed on egg production have been re- ported by many researchers (Payne et al., 2005; Leeson et al., 2008; Suchy et al., 2014; Han et al., 2017). The previous findings showed incon- sistent results on the effect of Se in the diet on egg production. This inconsistency was due to a couple of factors affecting egg production, such as the concentration of Se in the diet and the source of Se (Arpasova et al., 2009). A study from Payne et al., (2005) showed that the addi- tion of Se in the diet, either in the form of sodi- um selenite or Se yeast did not increase egg pro- duction. Leeson et al. (2008) found that increas- ing Se concentration from 0.1 ppm to 0.3 ppm in the feed increased egg production from 64.9 to 72.3%. In this present study, the addition of fer- mented PKC with the addition of Se (T1 to T4) increased egg production from 412 eggs (T-0) to between 430 and 438 eggs (T-1 to T-4). Henday production, egg weight, and total egg production during the study also increased with the addition of Se in the form of SRFPKC. Feeding Selenium-rich Fermented Palm Kernel Cake to Laying Hens (B. Sundu et al,) 41 The increase in total egg production follows a logarithmic pattern with Y = 570.78ln(x) + 21404 and R² = 0.9446. Total egg production increased dramatically when the diet was supple- mented with 0.87 ppm Se (T-1) and further addi- tion of 2.86 ppm Se (T-4) produced only a very small increase in total egg production. The same logarithmic pattern was also shown in other egg production parameters such as hen day and egg weight. The non-significant differences in all egg production parameters between the addition of Se with a concentration of 0.87 ppm in T-1 and 2.86 ppm in T-4 (Table 2) may indicate that a concentration of 0.87 ppm is sufficient to opti- mize egg production, adding more than this level could not increase egg production. Although the addition of Se at concentra- tions exceeding 0.87 ppm did not increase egg production, the Se content of eggs increased with increasing Se concentrations in the feed. Laying hens fed SRFPKC with a concentration of 2.86 ppm (T-4) produced eggs with the highest Se concentration. These findings indicate that the bioconversion of inorganic to organic Se occurs in this study with an indicator of Se stored in eggs. Liu et al (2020) found that the addition of Se in the feed can increase the Se content of eggs. The effect of additional treatment of Se concentration in the feed did not affect egg cho- lesterol in this present study. Even though cho- lesterol deposition in the egg can be affected by nutrition, particularly fatty acid content (Shahid et al., 2015), the unchanged lipid content in the present experimental diet might be the reason why the cholesterol content of the eggs was unaf- fected due to the addition of selenium to the diet. Table 3. Effect of diets on egg production, feed intake, FCR, dry matter excreta, feed digestibility, egg selenium, and egg cholesterol Parameters Treatment diets T-0 T-1 T-2 T-3 T-4 P- Value SEM Egg production (egg) 412 b 430 a 431 a 432 a 438 a >0.001 1,84 Henday production (%) 81,8 b 85,3 a 85.6 a 85.7 a 86.9 a >0.001 0,366 Total production (g) 20423 b 21558 a 21640 a 21715 a 22008 a >0.001 117 Egg weight (g/egg) 49,6 b 50.1 a 50.2 a 50.3 a 50.3 a 0.027 0,085 Feed intake (g) 50933 51779 52080 51624 52401 0.055 167 FCR 2.49 a 2.40 ab 2.41 ab 2.38 b 2.38 b 0.008 0,012 DM excreta (%) 20.9 22.1 22.6 22.6 22.7 0.956 0,772 DM digestibility (%) 79.8 b 81.9 a 81.7 a 81.7 a 81.6 a >0.001 0,183 Prot. digestibility (%) 81.7 b 83.7 a 83.9 a 83.7 a 83.8 a >0.001 0,191 Egg selenium (mcg/100g) 53.4 c 80.7 b 80.6 b 81.8 b 90.7 a >0.001 2,42 Egg cholesterol (mg/100g) 773 712 842 698 630 0.076 25,2 FCR: feed conversion ratio; DM: dry matter; Prot: protein; SEM: Standard error of means Table 4. Egg quality of hens stored for 1 day at room temperature Parameters Experimental diets T-0 T-1 T-2 T-3 T-4 P- Value SEM Index of egg shape 0.0135 0.0128 0.0126 0.0125 0.0123 0.077 0.0037 Loss of egg weight (%) 1.353 1.284 1.255 1.252 1.229 0.989 0.0733 Egg yolk (%) 25.05 24.84 24.50 22.90 24.38 0.347 0.3360 Egg albumen (%) 63.30 62.55 63.74 66.01 64.01 0.681 1.0300 Eggshell (%) 11.65 12.61 11.76 11.09 11.61 0.064 0.1680 Height of albumen (mm) 6.64 6.59 6.68 6.79 6.88 0.796 0.0790 Height of yolk (mm) 13.43 13.23 13.50 13.21 13.65 0.742 0.1150 Eggshell thickness (mm) 0.38 0.37 0.39 0.34 0.36 0.189 0.0064 Yolk colour 8.0 8.8 8.2 8.0 9.3 0.323 0.2430 Index of yolk 0.310 0.311 0.316 0.313 0.317 0.954 0.0032 Haugh unit 83.60 83.71 83.68 83.79 83.75 1.000 0.4360 42 J. Indonesian Trop. Anim. Agric. 48(1):37-46, March 2023 This finding is supported by a study by Mohiti- Asli et al (2010). The increase in total egg production by 5.6 – 7.8% due to the addition of Se before the fer- mentation process in this study, was not caused by the increase in feed intake. The FCR was also affected by the addition of selenium-rich PKC. This study was not in line with previous research from Han et al. (2017) who found that the addi- tion of Se in the diet did not affect the FCR. An increase in egg production without being accom- panied by an increase in feed intake indicates that there might be an increase in income over feed cost which is the main target in the live- stock business. The addition of SRFPKC increased dry mat- ter digestibility of the diets from 80% to 82% and protein digestibility from 82% to 84%. Alt- hough there was improved feed digestibility, the increased feed intake to produce more eggs led to the unimproved FCR. This might indicate that more digested nutrients in hens fed the supple- mental selenium diets were not fully compen- sated in egg production. The increase in digesti- bility may be due to two mechanisms. First, fer- mentation on a substrate rich in fiber and man- nose-based polysaccharides can produce several enzymes, such as cellulase (Hatta et al., 2014) and mannanase (Bahri et al., 2019). These two enzymes are responsible for the breakdown of cellulose and mannan which are the main com- ponents of fibrous substances in PKC (Sundu et al., 2012). A study by Bahri et al. (2019) on the fermentation process of coconut meal having similar profiles in non-starch polysaccharides also indicated that fermentation of coconut meal produced a product in the form of mannose and the highest product of mannose was produced when the coconut meal was fermented for 5 days. The conversion of mannose-based polysac- charides into simple and easily digestible prod- ucts in the form of mannose and the presence of enzyme products enabled the diets containing fermented PKC to have a higher digestibility than the control diet in this study. Therefore, this condition could increase the digestible dry matter intake and the digestible protein intake. Second, the addition of Se from SRFPKC can improve the health status of the digestive tract. Read- Snyder et al. (2009) found longer small intestinal villi in the Se-fed chickens than the intestinal villi of chickens without the addition of Se. Im- proving the health of the digestive tract allows the hens to be able to absorb nutrients in the in- testinal villi. Although there was an increase in digestibility, the water content of the excreta was not affected by the addition of Se in this study. Although there was an increase in egg pro- duction due to the addition of SRFPKC, the per- centage of each part of the egg (yolk, albumen, and eggshell) was not affected. This finding was in agreement with the previous findings of Gjor- govska et al. (2012). Our results also indicated that egg quality measured one day after egg col- lection was statistically the same. This means that the influence of external factors such as tem- Table 5. Egg quality of hens stored for 30 days at room temperature Parameters Experimental diets T-0 T-1 T-2 T-3 T-4 P- Value SEM Index of egg shape 0.787 0.772 0.815 0.778 0.768 0.672 0.0106 Loss of egg weight (%) 5.13 b 4.22 a 4.37 a 4.34 a 4.24 a 0.039 0.111 Egg yolk (%) 26.6 28.8 25.5 25.0 24.3 0.358 0.732 Egg albumen (%) 61.6 58.3 62.3 63.3 63.2 0.208 0.757 Eggshell (%) 11.9 12.9 12.2 11.7 12.5 0.359 0.207 Height of albumen (mm) 3.09 c 3.55 bc 3.60 bc 3.79 ab 4.18 a >0.001 0.862 Height of yolk (mm) 7.48 b 8.39 a 8.67 a 8.89 a 9.12 a >0.001 0.132 Eggshell thickness (mm) 0.458 0.368 0.420 0.412 0.403 0.245 0.0124 Yolk colour 7.8 7.2 7.5 7.3 7.5 0.559 0.124 Index of yolk 0.164 b 0.197 a 0.196 a 0.197 a 0.211 a >0.001 0.0038 Haugh unit 51.91 b 60.45 a 60.47 a 60.75 a 62.42 a 0.001 0.942 Feeding Selenium-rich Fermented Palm Kernel Cake to Laying Hens (B. Sundu et al,) 43 perature and storage time in this study was mini- mal or not even detected on 1 day of storage. It is believed that albumen height and Haugh unit are affected by selenium (Pappas et al., 2005) storage time, and storage temperature (Gravena et al., 2011). Storage of eggs for 30 days affected the albumen height and Haugh unit of eggs fed SRFPKC diet. The Haugh unit value of eggs without SRFPKC stored for 30 days at room temperature was 51.91 and the addition of SRFPKC could maintain the Haugh unit value in the range between 60 and 62. Albumen height, yolk height, and yolk index also showed the same trend where the addition of SRFPKC could maintain the quality of albumen and yolks at 30 days of storage. This study showed that the high selenium content of eggs fed with SRFPKC plays a role in protecting the internal quality of eggs (Leeson et al., 2008). The increased Se con- centration in the diets increased linearly the albu- men thickness of eggs stored at ambient temper- ature for 30 days with a linear equation of Y = 0.3649x + 3.0822 and R 2 = 0.9346. Selenium has been believed to play a role in the production and activity of glutathione peroxidase (GSH-Px). The yolk index of poultry was better fed on diets supplemented with Se (T-1, T-2, T-3, and T-4) than those of control eggs (T-0). This is probably due to the production and activity of GSH-Px as an antioxidant enzyme and this enzyme functions to maintain cell integrity and protect the eggs from yolk lipid oxidation. Measurement of thio- barbituric acid reactive substances (TBARS) to determine fatty acid peroxidation in egg yolk lipids was carried out by Gajcevic et al. (2009) who found that the concentration of TBARS in egg yolk lipids as an indicator of lipid peroxida- tion was lower in chicken eggs fed with Se. Research on the effect of storage time on egg weight reduction has been carried out by Hatta et al. (2020). They found that fermentation slowed down the egg weight loss during 28 days of storage. The results of this study also showed that the effect of fermentation with the addition of sodium selenite could suppress the decrease in egg weight during 30 days of storage. The de- crease in egg weight may indicate that water evaporation occurs and maximum water evapora- tion occurs in eggs produced by chickens fed diets without SRFPKC supplementation. Since egg weight loss is related to the number and size of the pores of the eggshell, the addition of SRF- PKC might reduce the number and size of the pores of the eggshell and thus reduce the evapo- ration of water in the albumen and egg yolk. Studies on the effect of Se supplementation in laying hens’ diet on yolk color and egg shape index have been carried out by a number of au- thors (Renema and Sefton 2004; Arpasova et al., 2009; Han et al., 2017; Liu et al., 2020). They found non-significant differences in yolk color (Han et al., 2017; Arpasova et al., 2009) due to dietary supplementation with Se. It has long been believed that yolk coloration is much related to the carotenoid content of the diet (Rezaei et al., 2019). The similar yolk color found, in all eggs might indicate that there was not much change in the carotenoid content of the experimental diets due to the supplementation of SRFPKC. Since the egg shape index is influenced not by the diets but by genotype (Shaker et al., 2017), age of hens, and ambient temperature (Nikolova and Kocevski, 2006), it is expected that the effect of supplementation of SRFPKC in the diet on egg shape index is statistically undetected in this pre- sent study. This finding is in accordance with the study of Liu et al. (2020). CONCLUSION Palm kernel cake fermentation with the ad- dition of sodium selenite as a source of selenium can increase the selenium content of palm kernel cake, increase egg production, feed digestibility, egg selenium content, improve feed conversion, egg quality of both the yolk and albumen and slow down the egg weight loss stored for 30 days at room temperature. ACKNOWLEDGMENT We would like to thank the Ministry of Edu- cation, Culture, Research, Technology, and Higher Education for the research funding assis- 44 J. Indonesian Trop. Anim. Agric. 48(1):37-46, March 2023 tance so that this research can be carried out. We also thank the Rector of Tadulako University and the Dean of the Faculty of Animal Husbandry and Fisheries for the research facilities. We also thank the field laboratory staff and students for all their help. REFERENCES Ahsan, U., Z. Kamran, I. Raza, S. Ahmad, W. Babar, M. H. Riaz and Z. Iqbal. 2014. Role of Selenium in male reproduction: A review. Anim. Reprod. Sci. 146: 55-62 Almeida, I. M. C., M . T . Oliva-Teles, J. S a n- tos, C . Delerue-Matos and M . B . P . Oliveira. 2015. Total selenium content of commercial food supplements: Label ac- curacy evaluation. Austin J. Nutr. Food Sci. 3: 4. AOAC. 1990. Association of Official Analyti- cal Chemist Official Methods of Anal- yses. Third Edition. AOAC. Washington DC. Arpasova, H., V. Petrovic, M. Mellen, M. Ka- caniova, K. Cobanova and L. Leng. 2009. The effects of supplementing sodium sele- nite and selenized yeast to the diet for lay- ing hens on the quality and mineral con- tent of eggs. J. Anim. Feed Sci. 18: 90- 100 Bahri, S., B. Sundu and M. R. Aprianto. 2019. Mannanase activity Produced through fer- mentation of coconut flour at various pH by Aspergillus niger. J. Physics, Conf. series. 1242. 012009. Doi: 10.1088/1742- 6596/1242/1/012009. IOP. Publishing. Beck, M. A., D. Williams-Toone and O. A. Levander. 2003. Coxsackievirus B3- resistant mice become susceptible in Se/ vitamin E deficiency. Free Radic. Biol. Med. 34: 1263–1270. Cai, Z., J. Zhang and H. Li. 2019. Selenium, aging and aging-related diseases. Aging Clin Exp Res. 31:1035‐1047. Chen, Y. C., K . S . Prabu and A . M . Mas- tro. 2013. Is selenium a potential treat- ment for cancer metastasis? Nutrients, 5: 1149-1168. Demirci, A., A. L. Pometto and D. J. Cox. 1999. Enhanced organically bound selenium yeast production by feed-batch fermenta- tion. J. Agric. Food Chem. 47: 2496-2500. Flores-Mateo, G., A. Navas-Acien, R. Pastor- Barriuso and E. Guallar. 2006. Selenium and coronary heart disease: a meta- analysis. Am J Clin Nutr. 84:762-73. Gajcevic, Z., G. Kralik, E. Has-Schon and V. Pavic. 2009. Effects of organic selenium supplemented to layer diet on table egg freshness and selenium content, Italian J. Anim. Sci. 8: 189-199. Gjorgovska, N., F. Kiril, L. Vesna and K. Tosho. 2012. The effect of different levels of sele- nium in feed on egg production, egg quali- ty and selenium content in yolk. Lucr. Sti- int. 57:270-274. Gravena, R. A., R. H. Marques, J. Roccon, J. Picarelli, F. H. Hada, J. D. T. Da Silva, S. A. De Quiroz and V. M. B. De Moraes. 2011. Egg quality during storage and dep- osition of minerals in eggs from quails fed diets supplemented with organic selenium, zinc and manganese. Rev. Bras. Zootec. 40: 2767-2775. Han, X. J., P. Qin, W. X. Li, Q. G. Ma, C. Ji, J. Y. Zhang and L. H. Zhao. 2017. Effect of sodium selenite and selenium yeast on performance, egg quality, antioxidant ca- pacity, and selenium deposition of laying hens. Poult. Sci. 96: 3973-3980. Hatta, U., O. Sjofjan, I. Subagiyo and B. Sundu. 2014. Effects of fermentation on nutritive value of copra meal, cellulase activity and performance of broiler chickens. Livest. Res. Rural Dev. 26: 4. Hatta, U., S. Mozin, A. Adjis and B. Sundu. 2020. Fermentation of Selenium-added coconut dregs improve chicken egg pro- duction and slow down the deterioration of egg quality during 28 days storage. Livest. Res. Rural Dev. 32: 12 Huang, Z., A. H. Rose and P . R . Hoffmann. 2012. The role of Selenium in inflamma- tion and immunity: from molecular Feeding Selenium-rich Fermented Palm Kernel Cake to Laying Hens (B. Sundu et al,) 45 mechanisms to therapeutic opportunities. Antioxid. Redox Signal. 16: 705-743. Kleiner, I. S. and L. B. Dotti. 1962. Laboratory instruction in Biochemistry. 6 th edition. The C. V. Mosby Company, New York Leeson, S., H. Namkung, L. Caston, S. Durosoy and P. Schlegel. 2008. Comparison of selenium levels and sources and dietary fat quality in diets for broiler breeders and layer hens. Poult. Sci. 87: 2605-2612. Liu, H., Q. Yu, C. Fang, S. Chen, X. Tang, K. M. Ajuwon and R. Fang. 2020. Effect of selenium source and level on perfor- mance, egg quality, egg selenium content and serum biochemical parameters in lay- ing hens. Foods, 9: 68. Mohiti-Asli, M., F. Shariatmadari, and H. Lot- follahian, 2010. The influence of dietary vitamin E and selenium on egg production parameters, serum and yolk cholesterol and antibody response of laying hen ex- posed to high environmental temperature. Arch. Geflügelk. 74: 43-50 Mozin, S., U. Hatta, S. Sarjuni, M. Gobel and B. Sundu. 2019. Growth performance, feed digestibility and meat selenium of broilers fed fungi-fermented rice bran with addi- tion of inorganic selenium. Int. J. Poult. Sci 18: 438-444 Nikolova, N. and D. Kocevski. 2006. Forming egg shape index as influenced by ambient temperatures and age of hens. Biotechnol. Anim. Husb. 22. 119-125. Payne, R. L., T. K. Lavergne and L. L. South- ern. 2005. Effect of inorganic versus or- ganic selenium on hen production and egg selenium concentration. Poult. Sci. 84: 232-237. Pesti, G. M., B. R. Miller and R. Chambers. 1986. User-Friendly feed Formulation Program (UFFF) version 1.11 – 256 k. Department of Poultry Science and Agri- cultural economics. The University of Georgia Atlanta. Read-Snyder, J., F. W. Edens, A. H. Cantor, A. J. Pescatore and J. L. Pierce. 2009. Effect of dietary selenium on small intestine villus integrity in reovirus-challenged broilers. Int. J. Poult. Sci. 8: 829-835. Renema, R. A. and A. E. Sefton. 2004. Dietary selenium sources can affect egg produc- tion, shell quality and fertility traits of broiler breeders. XXII World’s Poult. Congress, 8-13 June, Istanbul Turkey. Rezaei, M., S. Zakizadeh, and N. Eila. 2019. Ef- fects of Pigments Extracted from the Mari- gold Flower on Egg Quality and Oxidative Stability of the Egg Yolk Lipids in Laying Hens. Iran. J. Appl. Anim. Sci. 9: 541– 547. Shaker, A. S., S. M. S. Kirkuki, S. R. Aziz, and B. J. Jalal. 2017. Influence of Genotype and Hen Age on the Egg Shape Index. Int. J. Biochem. Biophys. Mol. Biol. 2: 68-70. Steel, R. G. D. and J . A . Torrie. 1980. Princi- ples and procedures of statistics. New York, McGraw Hill. Suchy, P., E. Strakova and I. Herzig. 2014. Sele- nium in poultry nutrition: a review. Czech J. Anim. Sci. 59: 495-503 Shahid, S., C. Naila, R. U. Khan, S. M. Suhail, N. A. Khan. 2015., "Alternations in Cho- lesterol and Fatty Acids Composition in Egg Yolk of Rhode Island Red x Fyoumi Hens Fed with Hemp Seeds (Cannabis sativa L.)". J. Chem. Article ID 362936. Sundu, B., U. Hatta and A. S. Chaudhry. 2012. Potential use of beta mannan from copra meal as a feed additive for broilers. World’s Poult. Sci. J. 68: 707- 716. Sundu, B., U. Hatta, S. Mozin and A. Adjis. 2019. The effect of fermented coconut dregs with the addition of inorganic sele- nium on feed digestibility, growth perfor- mance and carcass traits of broiler chick- ens. Livestock Res. Rural Dev. 31: 11. Surai, P. 2006. Selenium in nutrition and Health. Nottingham University Press. Notting- ham. WHO, 2020. WHO Coronavirus (COVID-19) Dashboard. https://covid19.who.int/. Ac- cessed on 25 th of October 2020. Zhang, J., E. W. Taylor, K. Bennett, R. Saad, and M. P. Rayman. 2020. Association https://scholar.google.com/citations?view_op=view_citation&hl=id&user=QS_znkAAAAAJ&citation_for_view=QS_znkAAAAAJ:tOudhMTPpwUC https://scholar.google.com/citations?view_op=view_citation&hl=id&user=QS_znkAAAAAJ&citation_for_view=QS_znkAAAAAJ:tOudhMTPpwUC https://scholar.google.com/citations?view_op=view_citation&hl=id&user=QS_znkAAAAAJ&citation_for_view=QS_znkAAAAAJ:tOudhMTPpwUC https://scholar.google.com/citations?view_op=view_citation&hl=id&user=QS_znkAAAAAJ&citation_for_view=QS_znkAAAAAJ:tOudhMTPpwUC https://covid19.who.int/ https://covid19.who.int/ javascript:; javascript:; javascript:; javascript:; javascript:; 46 J. Indonesian Trop. Anim. Agric. 48(1):37-46, March 2023 between regional selenium status and reported outcome of COVID-19 cases in China. The American J. Clin. 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