Journal

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Tropical Animal Science

Faculty of Animal Science Building, IPB University (Bogor Agricultural University) Jln. Agatis, Kampus IPB Darmaga, Bogor Indonesia 16680

Phone/Fax: +62 251 8421692

E-mail: [email protected]; [email protected] Website: http://journal.ipb.ac.id/index.php/tasj

FORM B

PREQUALIFICATION REVIEW

Paper Title: Feeding Value of Fermented Coconut Dregs With Ammonium Sulfate Addition in Broiler Diets

Comments (please use additional paper if more space is needed)

No Comments Author’s response

1 Title:

The term “Feeding value’ is not suitable with the content of the manuscript. The author should focus on variables measured in the treatment, such as fermentation quality and performance of broliler

The title has been revised, being

“Fermented coconut dregs quality and their effects on performance of

broiler”

2 Introduction :

 Why choose coconut dregs?

 Author did not explain what the potency of coconut dreg, nutrient content or the use of coconut dreg in the broiler diet.

 Author only focus on fermentation

technique and ammonium sulfate addition

 What the correlation between coconut dreg and ammonium sulfate addition?

 Author should also write the no novelty statement in the introduction

- Information on the reason of using coconut dregs has been added into the introduction section.

- Nutrients content of coconut dregs has also been inserted.

- Thes study did focuss on fermentation and the use of ammonium sulfate.

- Low concentration of protein in coconut dregs is the reason of using ammonium sulfate.

- Novelty of the study has been clearly added into the text.

3 Data Comprehensiveness and Presentation

 There was no replication measurement (standar deviation) on fermented product (Nutrient content and amino acid/ Table 4 &

4)?

 Please check the decimal?? It should be written in dot ( . ) not comma ( , ).

 Please make standard table for the factorial design (Table 5 & 6). Please see other published article on how to write Table with factorial design or consult with statisticians.

- The fermented coconut dregs were analysed in duplicate samples and thus expressed withou standard deviation . Information on

duplicate sample has been added in the Material and Methods.

- The written expression of decimal has been revised to use dot, instead of comma.

- The table of factorial design has

been modified.

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Tropical Animal Science

Journal

Faculty of Animal Science Building, IPB University (Bogor Agricultural University) Jln. Agatis, Kampus IPB Darmaga, Bogor Indonesia 16680

Phone/Fax: +62 251 8421692

E-mail: [email protected]; [email protected] Website: http://journal.ipb.ac.id/index.php/tasj

4 Conclusion:

Please do not use number in the conclusion.

Conclusion should be written briefly in single paragraph, but reflects the experimental results obtained.

Conclussions has been revised according to the journal’s guidelines

5 References:

a) Please rewrite References according to the journal’s guidelines.

b) Please add the last 10 year journal publications. According to the journal

guidelines, it should be more than 80% of the total references.

References has been checked and revised and some of the relatively old referneces have been taken out and changed to the more current

references.

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September 2020 219 HAFSAH ET AL. / Tropical Animal Science Journal 43(3):219-226

PROOF

p-ISSN 2615-787X e-ISSN 2615-790X

Accredited by Directorate General of Strengthening for Research and Development No: 30/E/KPT/2018

Tropical Animal Science Journal, September 2020, 43(3):219-226 DOI: https://doi.org/10.5398/tasj.2020.43.3.219 Available online at http://journal.ipb.ac.id/index.php/tasj

INTRODUCTION

Application of fermentation technology in poultry nutrition is widely established for the improvement of the feed quality. Mechanisms behind the improved feeding value of diets were through several modus operandi. Production of simple substances, bioconversion of inorganic minerals into an organic fraction (Sugiharto

& Rantjitkar, 2019; Sukaryana et al., 2010), elimination of toxic compounds (Nyamete et al., 2016), and improved aroma (Sukaryana et al., 2010; Saunshia et al., 2018) were some of the fermentation benefits when fermentation technologies were applied in feed technology. Among the existed fermentation technologies, a solid-state fermentation has been widely used due to its practicality, environmentally friendly, and relatively low cost (Kapilan, 2015; Abhiney et al., 2012). The utilization of agricultural by-products as a solid substrate provides nutrient and physical support for the growth of microorganisms (Kumar & Kanwar, 2012).

Coconut dreg (CD) is one of the agricultural waste products that are abundantly available in Indonesia.

Of 60.8 million tons of world coconut production, Indonesia produced 31.2% of global coconut, being the

Fermented Coconut Dregs Quality and Their Effects on the Performance of Broiler Chickens

Hafsah*, H. B. Damry, U. Hatta, & B. Sundu

Animal Husbandry Department, Faculty of Animal Husbandry and Fisheries, Universitas Tadulako, Palu, Central Sulawesi, Indonesia

*Corresponding author: email: [email protected] (Received 23-12-2019; 09-04-2020; Accepted 21-04-2020)

ABSTRACT

This study was conducted to determine the effects of the fermentation duration of coconut dregs (CD) by Saccharomyces cerevisiae and the addition of ammonium sulfate on the growth performance, feed digestibility, carcass, and digestive organ developments. A finely ground CD was autoclaved at 20 psi for 20 minutes and added distilled water to meet 80% moisture content. The autoclaved substrate was added with different concentrations of ammonium sulfate and fermented with Saccharomyces cerevisiae to produce Saccharomyces cerevisiae-fermented CD. A total of 192 day-old- unsexed Cobb broiler chicks were used and kept for 6 weeks. The birds were fed experimental diets ad-libitum. The experimental diets were produced by two durations of fermentation (5 days and 7 days) and three levels of ammonium sulfate (0%, 0.2%, and 0.4%) in 4 replicates. The experimental diets were offered ad-libitum and water were available at all times. Fermentation decreased lipid and crude fiber content of CD and the addition of ammonium sulfate increased protein content and amino acid concentration of CD. The bodyweight gain of birds increased when the CD was fermented for 5 days and with the addition of 0.2% ammonium sulfate. Dry matter digestibility and protein digestibility were improved when CD was added with 0.2% ammonium sulfate.

In conclusion, fermenting CD for 5 days increased body weight gain and the addition of 0.2%

ammonium sulfate improved the feeding value of the diet and growth of birds.

Keywords: ammonium sulfate; coconut dregs; fermentation period; poultry; Saccharomyces cerevisiae

world’s largest producer in 2017 (FAO, 2017). Since this waste product was of low quality with 36.7% crude fiber and 5.7% protein (Sundu et al., 2019), it uses in animal feed, particularly in poultry diet, is strictly limited or even scarce. An effort to increase its quality through solid-state fermentation has been made by Sundu et al.

(2019) with promising results. A solid-state fermentation technology requires fungi to utilize chemical compounds in the substrate and convert them into the more digestible nutrients.

The potential of this technology to bio convert inorganic minerals that might be toxic for monogastric animals into digestible organic substances has been reported by Mozin et al. (2019) and Sundu et al. (2019).

Saccharomyces cerevisiae and Aspergillus niger were the two fungi used to bio convert poisonous sodium selenite into the more absorbable minerals (Mozin et al., 2019) when rice bran was used as a solid substrate. The logic was based on the fact that microorganisms in the gut of ruminants could utilize poisonous non-protein nitrogen to generate microbial proteins that are beneficial for the host. Accordingly, when nitrogen and sulfur were sup- plied in the form of ammonium sulfate prior to fermentation, the microbes could convert these two minerals

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into amino acids, particularly sulfur-containing amino acids such as methionine and cysteine, in the substrate.

This hypothesis becomes the novelty of the study and differentiates this study from previous studies reported in the database.

Ammonium sulfate is an inorganic mineral containing nitrogen and sulfur in high concentrations, being 21% and 24%, respectively. Nitrogen is the main component of protein, while sulfur is the raw material for the synthesis of amino acids containing sulfur, methionine, and cysteine. Since microorganisms possess the capability to convert nitrogen into protein microbes, it is possible that fermenting coconut dregs as a low protein substrate with the addition of minerals containing nitrogen and sulfur could increase the amino acid concentration and thus improve the feeding value of the diet. Improving the quality of coconut dregs in the aspect of amino acid concentration is the main target and being the novelty of this study. Therefore, this study was conducted to determine the influence of ammonium sulfate levels and the fermentation duration of CD on the quality of CD, growth performance, carcass percentage, and the development of the digestive organ in broiler chickens.

MATERIALS AND METHODS Fermentation Procedure

Coconut dregs were purchased from the traditional local market and oven-dried at 50^oC for four consecutive days. The use of low temperatures in oven-drying was aimed at protecting the protein from Maillard reaction that could downgrade its quality. The oven-dried CD was finely ground to a size of 1-2 mm. The fine CD was used as a solid substrate for fermentation. The bakery yeast Saccharomyces cerevisiae (Fermipan^®) was purchased from the local supermarket. The fermentation process was carried out using a method of Jacob &

Prema (2006). The finely dried CD was then autoclaved for 20 minutes at 20 psi and then cooled to room temperature. The cooled substrates were added ammonium sulfate with concentrations of 0%, 0.2%, and 0.4% coconut dregs dry matter prior to the inoculation with 346 CFU/g of Saccharomyces cerevisiae or equivalent to 0.1%.

Total yeast was measured by using a culture method for the total viable count (Nissen et al., 2003). The substrates and ammonium sulfate were thoroughly mixed.

The addition of sterile distilled water into the mixture was conducted to meet an 80% moisture content. The mixtures were put in 2-kg transparent plastic bags and aerobically incubated. The fermentation was terminated on days 5 and 7. Also, the fermented substrate was collected and oven-dried at 50^oC for 48 hours. The fermented substrates were subject to the analysis of proximate (AOAC, 1990), bulk density, and water holding capacity (Kyriazakis & Emmans, 1995).

Experimental Diets

This study was designed with a 2 x 3 factorial arrangement of treatments with two different durations

of fermentation (5 and 7 days as used by Mozin et al., 2019) and three different levels of ammonium sulfate (0%, 0.2%, and 0.4%). All feed ingredients used were obtained from a local poultry shop. Full fat soybean was roasted for 5 minutes with a temperature of 100^oC to minimize the negative effect of trypsin inhibitor. A hammer mill with a screen size of 4.0 mm was used to grind the corn and roasted full fat soybean. Basal diets (Table 1) were formulated to meet the major nutrients requirements as recommended by NRC (1994) by using UFFF software. Experimental diets mixed by using a cement mixer were: 1) was Basal diet + 0.5% CD fermented for 5 days with 0% ammonium sulfate addition, 2) was Basal diet + 0.5% CD fermented for 5 days with 0.2%

ammonium sulfate addition, 3) was Basal diet + 0.5%

CD fermented for 5 days with 0.4% ammonium sulfate addition, 4) was Basal diet + 0.5% CD fermented for 7 days with 0% ammonium sulfate addition, 5) was Basal diet + 0.5% CD fermented for 7 days with 0.2% ammonium sulfate addition, and 6) was Basal diet + 0.5%

CD fermented for 7 days with 0.4% ammonium sulfate addition.

Birds and Cage

The experimental protocol was presented and approved by the Animal Ethics Committee of the Faculty of Animal Science and Fisheries, Tadulako University, Palu, Indonesia. A total of 192–day old unsexed Cobb broiler chicks were used in this study. The chicks were kept in 6 electrically heated brooder pens for seven days. The spread of New Castle Diseases was controlled by vaccinating the birds on day 3 using Vaksimune^®ND B1. The chicks were then transferred into 20 pens on day 7 and kept the chicks from day 7 to 42. The broilers were fed the experimental diets ad-libitum and water was available throughout the study, also data collection was

Table 1. Experimental basal diet

Ingredients Quantity (%)

Starter diet Grower diet

Full fat soybean meal 25.0 24.5

Corn 50.0 50.4

Fish meal 13.3 11.0

Rice bran 10.0 13.4

Dicalcium phosphate 0.80 1.10

Methionine 0.20 0.10

Lysine 0.20 0.10

Salt 0.20 0.20

Mineral and vitamin mix 0.30 0.20

Calculated nutrients

Crude protein 23.08 21.19

Metabolizable energy

(kcal/kg) 3141 3154

Methionine 0.66 0.51

Lysine 1.49 1.28

Selenium 0.26 0.23

Calcium 1.70 0.94

Phosphorus 0.71 0.66

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started from day 7. A plastic feeder and drinker were allocated inside each pen. The drinkers and pens were routinely cleaned.

Chemical and Physical Analysis

Representatives of fermented CD, feed, and excreta were sampled for determination of dry matter, protein, lipid, crude fiber, and ash using a standard method (AOAC, 1990). All samples were ground to pass through a screen size of 0.5 mm. Analysis of amino acids was based on the procedure used by Sundu et al., 2008. A method of Kyriazakis and Emmans (1995) was adopted to measure the bulk density of the CD. The measurement units are stated in g/cm³. Water holding capacity (WHC) was measured based on the method of Kyriazakis & Emmans (1995). One g oven-dried CD was placed in a 15 mL tube and was soaked with distilled water for one day. The soaked samples were centrifuged at 6000 G for 15 minutes. After centrifugation, the liquid was decanted and the solid residue was freshly weighed and oven-dried at 50^oC for 48 hours. The dried samples were weighed and calculated for WHC, and the WHC was expressed as g water/g CD. All the analysis was done in duplicate.

Digestibility Study

On day 35, two broilers from each experimental cage were randomly taken and put them in 24 metabolic pens for measurements of parameters of digestibility for a week. The birds were continuously offered the experimental diets for 7 days. To collect the fecal discharges, a plastic tray matching the size of each metabolic cage was individually placed underneath the cage. The collection of feces was carried out from days 38 to 41 from 07.00 am. The feces from each cage were individually weighed after discarding any feed particles, feathers, and the other contaminations by hand-picking. The uncontaminated feces were oven-dried at 50^oC for 3 days to measure the moisture content. The dried feces from each experimental cage were pooled and ground. The ground samples were analyzed for proximate fractions.

The measurements of feed digestibility were based on the total fecal collection method (Kong & Adeola, 2014).

Carcass and Digestive Organs Dimensions At the end of the study, all experimental broilers were sacrificed by cervical dislocation. The length of duodenum, jejunum, ileum, and the weight of the empty gizzard were individually measured. The dimensions of the digestive tract and organs were expressed as cm/

kg BW for the length of the small intestine and g/kg BW for gizzard. Removals of feathers, shank, neck, digestive tract, and organs were conducted to measure carcass, breast, and abdominal fat percentages (Jensen, 1984).

Statistical Analysis

The study used a completely randomized factorial design with two different durations of fermentation and three different concentrations of ammonium sulfate.

Data on nutrients profile due to fermentation and the addition of ammonium sulfate were descriptively analyzed while body weight gain, feed intake, FCR, carcass, abdominal fat, digestibility, and relative weight of digestive organs were subject to the analysis of variance to determine the two main effects and their interaction effects on the parameters measured (Seltman, 2018).

Significant effects detected by analysis of variance were further tested by least significant difference (LSD) test using a Minitab Statistical Program.

RESULTS

Data on nutrient profiles, bulk density, and water holding capacity of Saccharomyces cerevisiae-fermented CD are presented in Tables 2 and 3. Coconut dregs had 31.57% lipid content. Fermentation of CD without the addition of ammonium sulfate decreased lipid contents between 21.6% and 27.2%. The addition of ammonium sulfate further decreased lipid concentrations about 44.2% to 50.4%. Crude fiber of CD decreased, whereas crude protein of CD increased due to fermentation.

Physical properties such as bulk density and water holding capacity were improved due to the changes in nutritional concentration of fermented CD.

Amino acid concentrations increased as a result of fermentation. The addition of ammonium sulfate in the CD prior to fermentation expectedly increased amino

Table 2. Nutrients content, bulk density, and water holding capacity of coconut dregs or fermented coconut dregs

Nutrients Coconut

dregs

Treatments

FCD + 0% AS FCD + 0.2% AS FCD + 0.4% AS

5 days 7 days 5 days 7 days 5 Days 7 Days

Lipid (%) 31.57 24.76 22.96 15.64 17.59 18.67 17.69

Crude protein (%) 6.19 7.71 8.54 7.26 10.13 11.02 7.58

Crude fiber (%) 33.96 18.52 25.58 29.26 28.71 26.55 31.69

Ash (%) 3.60 2.83 5.21 2.2 1.63 2.14 1.22

Moisture (%) 6.51 5.82 6.35 7.00 8.64 8.52 8.21

Bulk density (g substrate/cm³) 0.222 0.250 0.270 0.251 0.274 0.273 0.272

WHC (g water/g substrate) 5.75 5.08 4.13 4.37 4.49 4.40 4.39

Note: FCD= Fermented coconut dregs; AS= Ammonium sulfate; WHC= Water holding capacity.

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acids containing sulfur, cysteine, and methionine, from undetected concentration (12 mg/kg for methionine and 161 mg/kg for cysteine) to detectable concentrations.

Growth performance, carcass percentage, and abdominal fat are presented in Table 4. The effect of duration of fermentation on body weight gain was statistically significant (p<0.05) in which fermenting CD for 5 days produced a better body weight gain. The addition of 0.2% ammonium sulfate in the medium increased body weight gain and FCR. Interaction between the du-

ration of fermentation and levels of ammonium sulfate did not significantly affect all parameters.

Data on feed digestibility, the relative length and weight of digestive tracts and organs of broiler chickens are presented in Table 5. Duration of fermentation did not produce any significant difference on digestibility of dry matter, protein, relative weight of gizzard, and relative length of the small intestine. Dry matter and protein digestibility were improved due to the addition of 0.2% ammonium sulfate in the CD before fermentation.

Table 3. Amino acids profile of coconut dregs and fermented coconut dregs (mg/kg)

Amino acids Coconut dregs

Treatments

FCD + 0% AS FCD + 0.2% AS FCD + 0.4% AS

5 days 7 days 5 days 7 days 5 days 7 days

Serine 1229 1869 3686 2747 5202 2695 2655

Phenylalanine 869 1266 2677 1682 3645 1962 1668

Isoleucine 738 1410 2742 1974 2783 2008 1690

Valine 1121 1958 3766 2799 4018 2892 2706

Alanine 1202 2167 4371 3302 3892 3100 2821

Arginine 1933 2181 4069 3106 5551 3489 2745

Glycine 1011 1665 3396 2447 4296 2347 2299

Lysine 1102 2282 4111 3738 3600 3482 3160

Leucine 1327 2359 4416 3072 4443 3184 2708

Tyrosine 485 717 1548 1125 2441 1219 1119

Threonine 982 1720 3712 2598 4751 2742 2759

Histidine 324 609 1198 908 1877 918 896

Cysteine UD UD UD UD 302 UD 183

Methionine UD UD UD 278 UD 210 UD

Tryptophan 488 667 805 815 861 849 854

Note: FCD= Fermented coconut dregs; AS= Ammonium sulfate; UD= undetected

Table 4. Growth performance of birds fed the experimental diets

Variables Fermentation Levels of ammonium sulfate (%)

Average**

0 0.2 0.4

Body weight gain (g) 5 days 1953±21.6 2019±67.7 1913±35.1 1962±61.8ᵃ

7 days 1898±8.26 1974±24.8 1900±58.0 1924±49.6ᵇ

Average* 1925±33.2ᵇ 1997±53.1ᵃ 1906±44.9ᵇ

Feed Intake (g) 5 days 3499±212 3389±571 3407±77 3431±324

7 days 3582±127 3198±510 3453±187 3411±335

Average* 3540±168 3293±511 3430±135

FCR 5 days 1.79±0.12 1.67±0.24 1.78±0.05 1.75±0.15

7 days 1.89±0.06 1.62±0.25 1.82±0.07 1.78±0.18

Average* 1.84±0.10ᵃ 1.65±0.23ᵇ 1.80±0.06ᵃ

Carcass (%) 5 days 66.2±3.67 65.4±6.67 69.5±2.64 67.0±4.61

7 days 70.4±0.81 65.7±5.10 69.2±4.39 68.4±6.33

Average* 68.3±3.37 65.5±8.15 69.4±3.36

Breast (%) 5 days 21.0±1.63 20.2±1.26 22.5±3.06 21,2±2.17

7 days 21.9±1.79 25.2±4.49 22.3±1.71 23.1±6.32

Average* 21.4±1.66 22.9±8.02 22.4±2.30

Abdominal fat (%) 5 days 2.26±0.46 1.64±0.91 1.88±0.41 1.93±0.63

7 days 1.00±0.19 2.09±0.47 1.75±0.41 2.05±0.42

Average* 2.29±0.32 1.87±0.71 1.81±0.39

Note: *= Means in the same row with different superscripts differ significantly (p<0.05); **= Means in the same column and in the same variable with different superscripts differ significantly (p<0.05).

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Organ dimensions (relative weight and length) were not affected by the addition of ammonium sulfate. There was no interaction between the duration of fermentation and the levels of ammonium sulfate on the digestibility of dry matter and protein, gizzard weight, and intestinal length.

DISCUSSION

Nutrient Profiles and Physical Properties of Fermented Coconut Dregs

It is expected that fermentation could lower the lipid content of the CD. This might indicate that the yeast Saccharomyces cerevisiae utilized the fat content of CD for a source of nutrients. The decreased fat concentration in CD due to fermentation was also reported by Mozin et al. (2019), who found that the fat content of rice bran decreased when it was fermented either by Saccharomyces cerevisiae or Aspergillus niger. The addition of ammonium sulfate into the CD prior to fermentation either at the level of 0.2 or 0.4% could further decrease the fat content of CD.

The crude fiber content of CD was relatively high, being 34%. The high concentration of crude fiber was dependent upon the contamination of a nutshell of coconut since the content of a nutshell was mainly lignin (Sundu et al., 2009). According to Mozin et al.

(2019), fermentation could decrease the fibrous fraction of the substrate. During fermentation of the CD, mannanase enzyme was produced to break down the fiber into simpler carbohydrates (Bahri et al., 2019) and thus decreased the concentration of crude fiber in the CD.

Since dietary fiber was bio-converted into a simple frac-

tion, the substrate becomes heavier, as was indicated by a high bulk density. This current finding indicated that bulk density increased due to the fermentation process.

Since fiber had the capacity to bind water (Ngoc et al., 2012), reducing the fiber content of the substrate could lower the capacity of the substrate to bind more water.

This logic assumption was supported by these current findings that fermentation decreased water holding capacity from 5.75 to between 4.13 and 5.08 g water/g substrate.

Although there was an increase in protein content due to fermentation, the addition of ammonium sulfate into the CD prior to fermentation could further increase the protein content of the substrate, particularly in CD supplemented with 0.2% ammonium sulfate fermented for 7 days and CD supplemented with 0.4% ammonium sulfate fermented for 5 days (Table 3). The same pattern was found in the concentrations of amino acids in which CD supplemented with 0.2% ammonium sulfate fermented for 7 days and CD supplemented with 0.4%

ammonium sulfate fermented for 5 days had a higher number of amino acids. Unexpectedly, the addition of more ammonium sulfate (0.4%) in the CD prior to fermentation could not produce higher concentrations of protein and amino acids. It can be stated here that the ideal concentration of ammonium sulfate supplementation to increase amino acids concentration was 0.2%. It is possible that the higher number of nitrogen in the CD supplemented with 0.4% ammonium sulfate fermented for 5 and 7 days were converted into ammonia and released to the air.

Amino acids containing sulfur (cysteine and methionine) present in CD were undetectable that was below 12 mg/kg for methionine and 161 mg/kg for cys- Table 5. Feed digestibility and digestive organs of broilers fed the experimental diets

Variables Fermentation Levels of ammonium sulfate (%) Average**

0 0.2 0.4

DMD (%) 5 days 80.3±0.36 83.5±0.81 82.9±0.52 82.2±1.55

7 days 80.2±1.71 82.3±0.74 81.8±2.04 81.5±1.71

Average* 80.3±1.14ᵇ 82.9±0.97ᵃ 82.4±1.49ᵃ

Protein digestibility (%) 5 days 84.0±0.82 86.2±1.20 86.2±1.11 85.5±1.44

7 days 83.2±0.39 85.3±0.85 84.1±3.01 84.2±1.86

Average* 83.6±0.72ᵇ 85.8±1.09ᵃ 85.1±2.37^ab

Gizzard (g/kg BW) 5 days 1.64±0.18 1.59±0.17 1.62±0.14 1.62±0.15

7 days 1.60±0.06 1.73±0.11 1.69±0.09 1.67±0.09

Average* 1.62±0.13 1.66±0.15 1.65±0.11

Duodenum (cm/kg BW) 5 days 9.4±1.41 8.2±1.18 9.5±1.61 9.0±1.42

7 days 8.2±0.99 9.5±0.50 9.7±1.64 9.1±1.24

Average* 8.8±1.30 8.8±1.09 9.6±1.51

Jejunum (cm/kg BW) 5 days 33.9±3.14 30.6±2.04 35.4±1.83 33.3±3.00

7 days 33.1±2.88 38.4±10.1 37.1±4.03 36.2±6.50

Average* 33.5±2.82 34.5±7.91 36.2±3.56

Ileum (cm/kg BW) 5 days 30.9±4.00 28.7±2.73 32.2±1.33 30.6±3.01

7 days 28.5±1.45 33.9±6.82 36.3±7.94 32.9±6.49

Average* 29.7±3.08 31.4±5.57 34.2±5.71

Note: DMD= Dry matter digestibility; BW= Body weight; *= Means in the same row with different superscripts differ significantly (p<0.05); **= Means in the same column with different superscripts differ significantly (p<0.05).

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teine. Fermenting the CD without ammonium sulfate supplementation still produced undetected methionine and cysteine. The addition of ammonium sulfate at the levels of 0.2 and 0.4% could increase the number of amino acids containing sulfur. Interestingly, the duration of fermentation could differently produce amino acids containing sulfur where cysteine was produced when the CD supplemented with ammonium sulfate was fermented for 5 days. Fermenting the substrate for 7 days produced a higher number of methionine as amino acid containing sulfur. These findings indicated that sulfur present in the ammonium sulfate was bio converted into an organic form of amino acids containing sulfur (methionine or cysteine) since sulfurs in methionine or cysteine amino acids might be originated from sulfur in ammonium sulfate supplemented in the CD.

Growth Performance, Abdominal Fat, and Carcass Percentage

Supplementation of diets with fermented substrate could produce heavier birds (Yasar et al., 2016). This result is related to the role of fermentation that could improve the feeding value of diets through the production of an enzyme (Kapilan, 2015). Since the duration of fermentation could affect the production of enzymes, the quality of the substrate relied on the duration of fermentation. It was clear that fermentation of CD for 5 days produced a better quality of the substrate since birds fed ration supplemented with fermented CD for 5 days had higher body weights. However, the mechanism of increased performance of birds fed ration supplemented with fermented CD was unclear since the digestibility of the diets was not affected by the duration of fermentation. It can be speculated that birds fed ration supplemented with CD fermented for 7 days could utilize more nutrients than birds fed ration supplemented with CD fermented for 5 days that converted the nutrients into waste products such as CO₂ and heat.

Feed intake, FCR, abdominal fat, carcass, and breast percentages of experimental birds were not affected by the duration of fermentation.

Feeding the experimental birds with a diet containing 0.2% ammonium sulfate and fermented CD increased the bodyweight gain of birds by about 3.7%.

This increase in body weight gain of birds might be related to the increase in dry matter and protein digestibility (Table 5), coupled with the increase in protein and amino acid concentrations. However, when the concentration of ammonium sulfate was increased to 0.4% included in the CD before fermentation, the body weight gain of birds fed the 0.4% ammonium sulfate diet was not improved compared to the birds fed the fermented CD that was not supplemented with ammonium sulfate.

This result is an anomaly since the dry matter digestibility of the ration increased. The possible reason might be that the inclusion of 0.4% ammonium sulfate could not enhance protein digestibility. It is possible that the addition of 0.4% ammonium sulfate in the substrate was too much in the sense of improving feeding value and thus

could not be recommended in the fermentation process when CD was used as substrates.

Since the experimental birds fed ration supplemented with 0.2% ammonium sulfate in the substrate were heavier while the birds consumed the same amount of feed as others, FCR of the diet was better. However, this bodyweight difference could not produce a higher percentage of carcass. Breast and abdominal fat of birds were also unaffected by the treatments.

Digestibility of Dry Matter, Protein, and Digestive Organs Dimensions

The effect of diets containing a fermented CD with the addition of ammonium sulfate on feed digestibility has not been reported in the database. The current findings indicated that dry matter digestibility of the diet was increased as a result of the addition of ammonium sulfate before fermentation. Ammonium sulfate might play a role in increasing the growth of the yeast.

Schmidt & Furlong (2012) found that the addition of ammonium sulfate in the medium could increase biomass production of fermented rice bran. The increase in the population and proliferation of Saccharomyces cerevisiae might improve the production of enzymes to hydrolyze and utilize the fiber fraction of CD for the maintenance of the yeasts. Bahri et al. (2019) found that when coconut waste product was fermented, a mannanase enzyme was produced. Early study of Hatta et al. (2014) also indicated the production of cellulase enzyme when copra or coconut meal was fermented using Trichoderma viride.

These two enzymes are responsible for the degradation of cellulose and non-starch polysaccharides rich in man- nose that are the main components of dietary fiber in coconut meal (Ngoc et al., 2012; Sundu et al., 2012). Once the digestibility of the dietary fiber of CD increased, the overall digestibility of dry matter was improved.

It has been well accepted that the addition of nitrogen in the medium could increase the production of protein (Akintomide & Antai, 2012). The supplementation of white yam peels as a substrate with ammonium sulfate before fermentation with Saccharomyces cerevisiae increased protein yield (Akintomide & Antai, 2012). Since solid-state fermentation aimed at producing enzymes, the enzymes produced were dependent upon the concentration of nutrients (Kapilan, 2015). Using coconut in the present study with a high concentration of lipid and the addition of ammonium sulfate, as a medium of fermentation with Saccharomyces cerevisiae might produce protease and lipase enzymes. Masyithah (2017) used coconut milk and fermented with Saccharomyces cerevisiae in her study found that lipase and protease enzymes were produced to break down molecules to produce coconut oil. The production of protease during fermentation and the addition of ammonium sulfate might generate more protease and thus increased protein digestibility in the current study.

Digestive organ dimensions, either gizzard and small intestine relative weights were not affected by the duration of fermentation and levels of ammonium

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sulfate. According to Sundu et al. (2009), digestive organ dimensions were partly caused by the dietary fiber of the diet, along with the live body weight of birds. The enlarged gizzards of birds fed copra meal-based diets were a response to accommodate more fibrous digests passing through the gizzard. Accordingly, the addition of only 1% fermented CD could not affect much the crude fiber concentration of the current diets. It thus could not produce any significant difference in the digestive organs dimension.

CONCLUSION

Fermentation at both 5 days and 7 days decreased lipid and the crude fiber content of coconut dregs. The addition of ammonium sulfate in the medium of coconut dregs increased protein and amino acids concentration. Moreover, the bodyweight gain, feed conversion ratio, dry matter digestibility, and protein digestibility improved due to ammonium sulfate addition in the coconut dregs before fermentation.

CONFLICT OF INTEREST

Burhanudin Sundu serves as an editor of the Tropical Animal Science Journal, but has no role in the decision to publish this article. The authors assure that this article has no conflict of interest with the funding body and any producers or institutions mentioned in this article.

ACKNOWLEDGEMENT

The authors would like to express our sincere thanks to the Ministry of Research, Technology and Higher Education through the Universitas Tadulako for providing the financial supports, enabling us to do this research. We would also like to thank the Faculty of Animal Husbandry and Fisheries for the research facilities used in this study. Our gratitude also goes to the students involved in this study for their supports in taking care of the birds and cleaning up the pens.

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org/10.5713/ajas.2014.r.02

Kumar, A. & S. S. Kanwar. 2012. Lipase production in solid- state fermentation (SSF): recent developments and biotech- nological applications. Dyn Biochem, Process Biotechnol.

Mol. Biol. 6:13-27.

Kyriazakis, I. & G. C. Emmans. 1995. The voluntary feed intake of pigs given feed based on wheat bran, dried citrus pulp and grass meal, in relation to measurements of feed bulk. Brit. J. Nutr. 73: 191-207. https://doi.org/10.1079/

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Masyithah, Z. 2017. Parametric study in production of virgin coconut oil by fermentation method. Oriental J. Chem. 33:

3069-3076. https://doi.org/10.13005/ojc/330647

Mozin, S., U. Hatta, S. Sarjuni, M. Gobel, & B. Sundu. 2019.

Growth performance, feed digestibility and meat selenium of broilers fed fungi-fermented rice bran with addition of inorganic selenium. Int. J. Poult. Sci. 18: 438-444. https://

doi.org/10.3923/ijps.2019.438.444

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& M. Pushpa. 2018. Improved fermentation of cocoa beans with enhanced aroma profiles. Food Biotechnol, 32: 257- 272. https://doi.org/10.1080/08905436.2018.1519444 Schmidt, C. G. & E. B. Furlong. 2012. Effect of particle size and

ammonium sulfate concentration on rice bran fermentation with the fungus Rhizopus orizae. Bioresource Technol.

123: 36-41. https://doi.org/10.1016/j.biortech.2012.07.081 Seltman, H. J. 2018. Experimental design and Analysis. Carnegie

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Sundu. B., A. Kumar, & J. Dingle. 2008. Amino acids digestibility of palm kernel meal in poultry. J. Indonesian Trop.

Anim. Agric. 33: 139-144.

Sundu, B., A. Kumar, & J. Dingle. 2009. Feeding Value of copra meal for Broilers. World’s Poult. Sci. J. 65: 481-492. https://

doi.org/10.1017/S0043933909000348

Sundu, B., U. Hatta, & 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. https://doi.

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Sundu, B., U. Hatta, S. Mozin, & A. Adjis. 2019. The effect of fermented coconut dregs with the addition of inorganic selenium on feed digestibility, growth performance and carcass traits of broiler chickens. Livest. Res. Rural Dev.

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org/10.3906/vet-1505-44

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Fermented Coconut Dregs Quality and Their Effects on Performance of Broiler 1

Chickens 2

ABSTRACT 3

ThisA study was done to determine the effects of duration of fermentation of coconut dregs 4

(CD) by Saccharomyces cerevisiae and the addition of ammonium sulfate on growth 5

performance, feed digestibility, carcass and digestive organ developments. A finely ground 6

CD was autoclaved at 20 psi for 20 minutes and added distilled water to meet 80% moisture 7

content. The autoclaved substrate was added with different concentration of ammonium 8

sulfate and fermented with Saccharomyces cerevisiae to produce Saccharomyces 9

cerevisiae-fermented CD. A total of 192 day-old-chicks were used and kept for 6 weeks.

10

The birds were fed experimental diets ad-libitum. The experimental diets were two 11

durations of fermentation (5 days and 7 days) and three levels of ammonium sulfate (0, 0.2 12

and 0.4%) in 4 replicates. The experimental diets were offered ad-libitum and water 13

available at all times. Each pen was equipped with a drinker and a feeder. The study used a 14

completely randomized factorial design with 2 different duration of fermentation, three 15

levels of ammonium sulfate and 4 replications. Fermentation could lowered the crude fibre 16

content of CD and addition of ammonium sulfate increased protein content and amino acid 17

concentration of CD. Bodyweight gain of birds was increased when the CD was fermented 18

for 5 days and with the addition of 0.2% ammonium sulfate. Dry matter and protein 19

digestibilities were improved when CD was added with 0.2% ammonium sulfate. In 20

conclusions, fermenting CD for 5 days increased body weight gain and the addition of 0.2%

21

ammonium sulfate could improved the feeding value of the diet and growth of birds.

22

Keywords: Ammonium sulfate, Coconut dregs, Fermentation, Poultry, Yeast 23

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2

INTRODUCTION 24

Application of fermentation technology in poultry nutrition is widely established for 25

the improvement of the feed quality. Mechanisms behind the improved feeding value of 26

diets were through several modus operandi. Production of simple substances, bioconversion 27

of inorganic minerals into an organic fraction (Sukaryana et al., 2010), elimination of toxic 28

compounds (Nyamete et al., 2016) and improved aroma (Sukaryana et al., 2010; Saunshia 29

et al., 2018) are to name some of the fermentation benefits when applied in feed 30

technology. Of fermentation technologies, a solid-state fermentation has been widely used 31

due to its practicality, environmentally friendly and relatively low cost (Kapilan, 2015;

32

Abhiney et al., 2012). Utilization of agricultural by-product as a solid substrate provides 33

nutrient and physical support for the growth of micro organisms (Kumar and Kanwar, 34

2012).

35

Coconut dregs (CD) is one of agricultural waste products that is abundantly 36

available in Indonesia. Of 60.8 million tonnes of coconut production, Indonesia produced 37

31.2% of global coconut, being the world’s largest producer in 2017 (FAO, 2017). Since 38

this waste product was of low quality with 36.7% crude fibre and 5.7% protein (Sundu et 39

al., 2019), its used in in animal feed, particularly in poultry diet, is strictly limited or even 40

scarce. An effort to increase its quality through solid-state fermentation has been made by 41

Sundu et al. (2019) with promising results. A solid-state fermentation technology requires 42

fungi to utilize chemical compounds in the substrate and convert them into more digested 43

nutrients.

44

The potential of this technology to bioconvert inorganic minerals that might be 45

toxic for monogastric animals into digestible organic substances has been reported by 46

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Mozin et al. (2019) and Sundu et al. (2019). Saccharomyces cerevisiae and Aspergillus 47

niger were the two fungi used to bioconvert poisonous sodium selenite into more 48

absorbable minerals (Mozin et al., 2019) when rice bran was used as a solid substrate. The 49

logic was based on the fact that micro organsms in the gut of ruminants could utilize 50

poisonous non-protein nitrogen to generate microbial proteins that are beneficial for the 51

host.

52

Ammonium sulfate is an inorganic mineral, containing Nitrogen nitrogen and 53

Ssulfur in high concentration, being 21% and 24% respectively. Nitrogen is the main 54

component of protein while sulfur is the raw material for sulfur-containing amino acids;

55

methionine and cysteine. Since micro organisms possess the capability to convert nitrogen 56

into protein microbes, it is possible that fermenting coconut dregs as a low protein substrate 57

with the addition of nitrogen and sulfur containing minerals could increase the amino acid 58

concentration and thus improve the feeding value of the diet. Improved the quality of 59

coconut dregs in the aspect of amino acid concentration is the main target and being the 60

novelty of this study. Therefore, a study was conducted to determine the influence of levels 61

of ammonium sulfate and duration of fermentation of CD on the quality of CD, growth 62

performance, carcass percentage and digestive organ development of broiler chickens.

63

. 64

MATERIALS AND METHODS 65

Fermentation procedure 66

Coconut dregs were purchased from the traditional local market and oven-dried at 67

50^oC for four consecutive days. The use of low temperatures in oven-drying was aimed at 68

protecting the protein from Maillard reaction that could downgrade its quality. The oven- 69

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4

dried CD was finely ground to a size of 1-2 mm. The fine CD was used as a solid substrate 70

for fermentation. The bakery yeast Saccharomyces cerevisiae (Fermipan^®) was purchased 71

from the local Supermarket. The fermentation process was carried out using a method of 72

Jacob and Prema (2006). The finely dried CD was then autoclaved for 20 minutes at 20 psi 73

and then cooled to room temperature. The cooled substrates were added ammonium sulfate 74

with different concentrations of 0, 0.2 and 0.4% prior to the inoculation with 346 CFU/g of 75

Saccharomyces cerevisiae or equivalent to 0.1%. The substrates and ammonium sulfate 76

were thoroughly mixed. The addition of sterile distilled water into the mixture was aimed at 77

meeting 80% moisture. The mixtures were put in 2-kg transparent plastic bags and 78

aerobically incubated. The fermentation was terminated on days 5 and 7. The fermented 79

substrate was collected and oven-dried at 50^oC for 48 hours. The fermented substrates were 80

subject to analysis of proximate (AOAC, 1990), bulk density and water holding capacity 81

(Kyriazakis and Emmans, 1995).

82

Experimental diets 83

This study was designed with a 2 X 3 factorial arrangement of treatments with two 84

different durations of fermentation (5 and 7 days) and three different levels of ammonium 85

sulfate (0, 0.2 and 0.4%). All the feed ingredients used were obtained from a local poultry 86

shop. Full fat soybean was roasted for 5 minutes with a temperature of 100^oC to minimize 87

the negative effect of trypsin inhibitor. A hammer mill with a screen size of 4.0 mm was 88

used to grind the corn and roasted full fat soybean. Basal diets (Table 1) were formulated to 89

meet the major nutrients requirements as recommended by NRC (1994) by using UFFF 90

software. The experimental diets (Table 2) were mixed by using a cement mixer.

91

Birds and cage 92

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The experimental protocol was presented and approved by the Animal ethics 93

committee of the Faculty of Animal Science and Fisheries, Tadulako University, Palu, 94

Indonesia. A total of 192 –day old unsexed broiler chicks were used in this study. The 95

chicks were kept in 6 electrically heated brooder pens for seven days. New Castle Diseases 96

spread was controlled by vaccinating the birds at day 3 using Vaksimune^®ND B1. The 97

chicks were then transferred into 20 pens for day 7 and kept the chicks from day 7 to 42.

98

The broilers were fed the experimental diets ad-libitum and water was available throughout 99

the study. A plastic feeder and drinker were allocated inside each pen. The drinkers and 100

pens were routinely cleaned.

101

Chemical and physical analysis 102

Representative fermented CD, feed and excreta were sampled for determination of 103

the dry matter, protein, lipid, crude fibre, and ash using a standard method (AOAC, 1990).

104

All the samples were ground to pass through a screen size of 0.5 mm. A method of 105

Kyriazakis and Emmans (1995) was adopted to measure the bulk density of the CD. The 106

measurement units are stated in g/cm³. Water holding capacity (WHC) was measured based 107

on the method of Kyriazakis and Emmans (1995). A 1 g oven-dried CD was placed in a 15 108

ml tube. The CD was soaked with distilled water for 1 day. The soaked samples were 109

centrifuged at 6000 G for 15 minutes. After centrifugation, the liquid was decanted. The 110

solid residue was freshly weighed and oven-dried at 50^oC for 48 hours. The dried samples 111

were weighed and calculated for WHC. The WHC was expressed as g water/ g CD. All the 112

analysis were done in duplicate.

113

Digestibility study 114

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On day 35, two broilers from each experimental cage were randomly taken and put 115

them in 24 metabolic pens for digestibility parameters for a week. The birds were 116

continuously offered with the experimental diets throughout 7 days. To collect the fecal 117

discharges, a plastic tray matching to the size of each metabolic cage were individually 118

placed underneath the cage. The collection of feces was carried out from days 38 to 41 at 119

07.00 am. The feces from each cage was individually weighed after discarding any feed 120

particles, feathers and other contaminations by hand-picking. The uncontaminated feces 121

were oven-dried for at 50^oC for 3 days to measure the moisture content. The dried feces 122

from each experimental cage were pooled and ground. The ground samples were analyzed 123

for proximate fractions. The measurements of feed digestibilities were based on the total 124

fecal collection method.

125

Carcass and digestive organs dimensions 126

At the end of the study, all the broilers were sacrificedkilled by cervical dislocation.

127

The length of duodenum, jejunum, ileum and the weight of empty gizzard were 128

individually measured. The dimensions of the digestive tract and organs were expressed as 129

cm/ kg BW for the length of the small intestine and g/kg BW for gizzard. Removals of 130

feathers, shank, neck digestive tract and organs were done to measure carcass, breast 131

abdominal fat percentages.

132

Statistical analysis 133

The study used a completely randomized factorial design with two different 134

durations of fermentation and three different concentrations of ammonium sulfate. Data on 135

nutrients profile due to fermentation and the addition of ammonium sulfate were 136

descriptively elucidated while body weight gain, feed intake, FCR, carcass, abdominal fat, 137

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digestibility and relative weight of digestive organs were subject to the analysis of variance 138

to determine the two main effects and their interaction effect (Seltman, 2018). Significant 139

effects detected by analysis of variance were further tested by least significant difference 140

(LSD) test using a Minitab Statistical Program.

141 142

RESULTS 143

Data on nutrient profiles, bulk density and water holding capacity of Saccharomyces 144

cerevisiae-fermented CD are presented in Tables 3 and 4. Coconut dregs had 31.57 % lipid 145

content. Fermentation of CD without addition of ammonium sulfate decreased lipid content 146

between 21.6 and 27.2%. The addition of ammonium sulfate could further decreased lipid 147

concentration by about 44.2 to 50.4%. Crude fibrer of CD was also decreased, whereas 148

crude protein of CD increased due to fermentation. An increased protein was found when 149

CD was fermented. Physical properties such as bulk density and water holding capacity 150

were improved due to the changes in nutritional concentration of fermented CD.

151

Amino acids concentration were increased as a result of fermentation. The addition 152

of ammonium sulfate in the CD prior to fermentation expectedly increased sulfur 153

containing amino acids, cysteine and methionine from undetected concentration (12 mg/kg 154

for methionine and 161 mg/kg for cysteine) to deteactable figures.

155

Growth performance, carcass percentage and abdominal fat are shown in Table 5.

156

The effect of duration of fermentation on bodyweight gain was statistically significant 157

(P<0.05) in which fermenting CD for 5 days produced a better bodyweight gain. The 158

addition of 0.2% ammonium sulfate in the medium increased body weight gain and FCR.

159

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Interaction between duration of fermentation and levels of ammonium sulfate did was not 160

significantly affect all paramaters.

161

Data on feed digestibility, the relative length and weight of digestive tract and organ 162

of broiler chickens can be seen in Table 6. Duration of fermentation did not produce any 163

significant difference on digestibilities of dry matter, protein, relative weight of gizzard and 164

relative length of small intestine. Dry matter and protein digestibilities were improved due 165

to the addition of 0.2% ammonium sulfate in the CD before fermentation. Organ 166

dimensions (relative weight and length) were not affected by the addition of ammonium 167

sulfate. There was no interaction between duration of fermentation and levels of 168

ammonium sulfate on digestibilities of dry matter and protein, gizzard weight and intestinel 169

length.

170 171

DISCUSSIONS 172

Nutrient profiles and physical properties of fermented coconut dregs 173

It is expected that fermentation could lower the lipid content of the CD. This might 174

indicate that the yeast Saccharomyces cerevisiae utilized the fat content of CD for a source 175

of nutrients. The decreased fat concentration in CD due to fermentation was also reported 176

by Mozin et al. (2019), who found that the fat content of rice bran decreased when it was 177

fermented either by Saccharomyces cerevisiae and Aspergillus niger. The addition of 178

ammonium sulfate into the CD either 0.2 or and 0.4% prior to fermentation could further 179

decrease the fat content of CD.

180

The crude fibrer content in CD was relatively high, being 34%. The high 181

concentration of crude fibrer was dependent upon the contamination of the nutshell of 182

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coconut as the nutshell was mainly lignin (Sundu et al. 2009). According to Mozin et al.

183

(2019) fermentation could decrease the fibrous fraction of the substrate. During 184

fermentation of the CD, mannanase was produced to break down the fibre into simpler 185

carbohydrates (Bahri et al., 2019) and thus decreased the concentration of crude fiber in 186

CD. Since more dietary fibrer was bioconverted into a simple fraction, the substrate 187

becomes heavier as indicated by high bulk density. This current finding indicated that bulk 188

density increased due to fermentation. As fibre had the capacity to bind water (Ngoc et al., 189

2012), reducing fibrer content of the substrate could lower the capacity of the substrate to 190

bind more water. This logic was supported by these current findings as fermentation 191

decreased water holding capacity from 5.75 to between 4.13 and 5.08 g water/g substrate.

192

Although there was an increase in protein content due to fermentation, the addition 193

of ammonium sulfate into the CD prior to fermentation could further increase the protein 194

content of the substrate, particularly in 0.2% ammonium sulfate fermented for 7 days and 195

0.4% ammonium sulfate fermented with 5 days (Table 3). The same pattern was found in 196

the concentration of amino acids in which 0.2% ammonium sulfate fermented for 7 days 197

and 0.4% ammonium sulfate fermented with 5 days had more amino acids. It is unexpected 198

that addition more ammonium sulfate (0.4%) in the CD prior to fermentation could not 199

generate more protein and amino acids. It can be stated here that the ideal concentration of 200

ammonium sulfate to increase amino acids concentration was 0.2%. It is possible that more 201

nitrogen in ammonium sulfate present in 0.4% ammonium sulfate fermented for 5 and 7 202

days was converted into ammonia and released to the air.

203

Sulfur containing amino acids (cysteine and methionine) present in CD was 204

undetectable as below 12 mg/kg for methionine and 161 mg/kg for cysteine. Fermenting the 205

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CD without ammonium sulfate supplementation still produced undetected methionine and 206

cysteine. The addition of ammonium sulfate 0.2 and 0.4% could increase sulfur-containing 207

amino acids. Interestingly, the duration of fermentation could differently produce sulphur 208

amino acids where cysteine was produced when the ammonium sulfate - added coconut 209

dregs was fermented for 5 days. Fermenting the substrate to 7 days produced more 210

methionine as sulfur amino acids. These findings indicated that sulfur present in 211

ammonium sulfate was bioconverted into an organic form of sulfur amino acids 212

(methionine or cysteine) as sulfur in methionine or cysteine in the amino acids might be 213

from sulfur in ammonium sulfate.

214

Growth performance, abdominal fat and carcass percentage 215

Supplementation of diets with fermented substrate could produce heavier birds 216

(Yasar et al., 2016). This is because fermentation could improve the feeding value of diets 217

through the production of an enzyme (Kapilan, 2015). Since the duration of fermentation 218

could affect the production of enzymes, the quality of the substrate relied on the duration of 219

fermentation. It seems that fermentation of CD for 5 days produced a better quality of the 220

substrate as birds fed the 5-days-fermented CD produced heavier birds. The mechanism of 221

increased performance of birds was unclear as the digestibility of the diets was unaffected 222

due to the duration of fermentation. Feed intake, FCR, abdominal fat, carcass and breast 223

percentages were not affected by the duration of fermentation.

224

Feeding the birds with diet containing the 0.2% ammonium sulfate - fermented CD 225

increased body weight gain of birds by about 3.7%. This increase in bodyweight gain of 226

birds might be related to the increase in dry matter and protein digestibilities (Table 5), 227

coupled with the increase in protein and amino acid concentration. However, when the 228

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concentration of ammonium sulfate was increased to 0.4% included in the CD before 229

fermentation, the body weight gain of birds fed the 0.4% ammonium sulfate diet was not 230

improved compared to the birds fed the fermented CD not unsupplemented with 231

ammonium sulfate. This is an anomaly as dry matter digestibility increased. The possible 232

reason might be that inclusion 0.4% ammonium sulfate could not enhance protein 233

digestibility. It is possible that the addition of 0.4% ammonium sulfate in the substrate was 234

too much in the sense of improving feeding value and thus could not be reccommended in 235

the fermentation process when CD were used as substrates.

236

Since the birds fed the 02% ammonium sulfate in the substrate were heavier while 237

the birds consumed the same amount of feed as others, FCR of the diet was better.

238

However, this bodyweight difference could not produce a higher percentage of the carcass.

239

Breast and abdominal fat of birds were also unaffected by the treatments.

240

Digestibilities of dry matter, protein and digestive organs dimensions 241

The effect of diets containing fermented CD with the addition of ammonium sulfate 242

on feed digestibility has not been reported in the database. The current findings indicated 243

that dry matter digestibility of the diet was increased as a result of the addition of 244

ammonium sulfate prior to fermentation. Ammonium sulfate might play a role in increasing 245

the growth of the yeast. Schmidt and Furlong (2012) found that the addition of ammonium 246

sulfate in the medium could increase biomass production of fermented rice bran. The 247

increase in the population and proliferation of Saccharomyces cerevisiae might improve the 248

production of enzymes to hydrolyze and utilize the fibrer fraction of CD for the 249

maintenance of the yeasts. Bahri et al. (2019) found that when coconut waste product was 250

fermented, a mannanase enzyme was produced. Early study of Hatta et al. (2014) also 251