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© 2025 by the authors; licensee Asian Online Journal Publishing Group 
 

Agriculture and Food Sciences Research 
Vol. 12, No. 2, 100-109, 2025 

ISSN(E) 2411-6653/ ISSN(P) 2518-0193 
DOI: 10.20448/aesr.v12i2.7312 

© 2025 by the authors; licensee Asian Online Journal Publishing Group 

 
 

 
 
 
Effects of additives and ensiling period on groundnut shell silage and in sacco 
rumen degradability characteristics 

 
Abba Ibrahim Abubakar1   

Abubakar Masud2   

Muktar Umar Muktar3   

Bilkisu Ahmad4   

Tukur Sani Tajo5    

Sani Ibrahim6   

Mahmud Suraj Abdullahi7   

 

 
( Corresponding Author) 

 
1,2,3,4Department of Animal Health and Production Technology, Federal Polytechnic, Kabo, Kano State, Nigeria. 
1Email: abbamusa35@yahoo.com   
2Email: masudabk79@gmail.com     
3Email: muktarumarmuktar91@gmail.com 
4Email: ummanabba122@gmail.com  
5Department of Science Laboratory Technology, Federal Polytechnic, Kabo, Kano, State, Nigeria. 
5Email: sanitajo88@gmail.com  
6Department of Animal Health Technology, Audu Bako College of Agriculture Dambatta, Kano State, Nigeria. 
6Email: ibrahimsanirogo@gmail.com 
7Department of Animal Science, Bayero University Kano, Nigeria.  
7Email: mahmudsuraj70@gmail.com  

 
Abstract 

This study evaluated the effects of additives and ensiling periods on the chemical composition and 
in sacco rumen degradability of groundnut shell (GNS). In phase one, a 3 × 5 factorial CRD was 
used with three ensiling periods (3rd, 5th, and 7th weeks) and five additives (control, urea, yeast, 
molasses, and NaOH). In phase two, in sacco degradability was determined using a 3 × 3 switch-
over design. Chemical composition was analyzed following AOAC procedures, and data were 
subjected to ANOVA. pH decreased with longer ensiling periods, reaching desirable levels (3.8–
5.0). Additives, period, and their interactions significantly (p<0.05) influenced proximate 
constituents and fibre fractions but not dry matter (DM) degradability. Urea and yeast increased 
crude protein (8.97% and 7.15%, respectively), while dry matter (DM) and crude fibre decreased 
after ensiling with additives. Crude protein rose and crude fibre declined with longer ensiling. The 
highest crude protein (9.58%) was from urea-treated GNS at 7 weeks. After 48 hours of 
incubation, DM disappearance peaked at 7 weeks for all additives, with urea and yeast yielding the 
highest potential degradability (100%). It is concluded that urea- or yeast-treated GNS ensiled for 
7 weeks improves nutrient quality and degradability, presenting a practical feed option for farm 
animals. 

 
Keywords: Additives, Ensiling, Degradability, Groundnut shell, Silage, In sacco, Rumen. 

 
Citation | Abubakar, A. I., Masud, A., Muktar, M. U., Ahmad, B., 
Tajo, T. S., Ibrahim, S., & Abdullahi, M. S. (2025). Effects of 
additives and ensiling period on groundnut shell silage and in sacco 
rumen degradability characteristics. Agriculture and Food Sciences 
Research, 12(2), 100–109. 10.20448/aesr.v12i2.7312 
History: 
Received: 28 March 2025 
Revised: 8 August 2025 
Accepted: 19 August 2025 
Published: 26 August 2025 
Licensed: This work is licensed under a Creative Commons 

Attribution 4.0 License  
Publisher:  Asian Online Journal Publishing Group 

Funding:  This study received no specific financial support. 
Institutional Review Board Statement: Not applicable. 
Transparency: The   authors   confirm   that   the   manuscript   is   an   
honest, accurate, and transparent account of the study; that no vital features of 
the study have been omitted; and that any discrepancies from the study as 
planned have been explained. This study followed all ethical practices during 
writing. 
Competing Interests: The authors declare that they have no competing 
interests. 
Authors’ Contributions: All authors contributed to the conception and 
design of the study. All authors have read and agreed to the published version 
of the manuscript. 

 

Contents 
1. Introduction .................................................................................................................................................................................... 101 
2. Materials and Methods ................................................................................................................................................................. 101 
3. Results and Discussion ................................................................................................................................................................. 102 
4. Conclusion ....................................................................................................................................................................................... 108 
References ............................................................................................................................................................................................ 108 
 

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mailto:muktarumarmuktar91@gmail.com
mailto:ummanabba122@gmail.com
mailto:sanitajo88@gmail.com
mailto:ibrahimsanirogo@gmail.com
mailto:mahmudsuraj70@gmail.com
https://creativecommons.org/licenses/by/4.0/
https://creativecommons.org/licenses/by/4.0/
https://www.doi.org/10.20448/aesr.v12i2.7312
https://orcid.org/0000-0001-9763-4795
https://orcid.org/0009-0009-4312-1156
https://orcid.org/0009-0008-6397-3877
https://orcid.org/0009-0004-5235-6348
https://orcid.org/0009-0001-2792-863X
https://orcid.org/0009-0001-0514-4172
https://orcid.org/0009-0000-6132-4680


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Contribution of this paper to the literature 

This work provides novel evidence that urea- or yeast-treated groundnut shells, when ensiled 
for seven weeks, significantly improve crude protein content and rumen degradability. It 
establishes an efficient, low-cost method or technique for upgrading an underutilized agro-
industrial by-product into a high-quality ruminant feed. 

 

1. Introduction 
Processing crops to obtain desired products typically generates large amounts of residues as by-products. In 

ruminant nutrition, many of these residues are valuable because they supply nutrients to animals, especially during 
periods of feed scarcity [1]. One such crop residue is the groundnut shell (GNS), which is produced in large 
quantities in many communities. 

An average of 1018 kg/ha of groundnut shell (GNS) is produced annually in Nigeria  [2]. With the exception 
of a small quantity used as fuel or mulching material, most are discarded as waste. It is common practice in Nigeria 
to either burn or leave them on the farm to decompose. Burning GNS contributes to global warming; therefore, 
there is a need to convert it into a useful feed resource [3]. However, one of the disadvantages of crop residues as 
feed is generally low palatability, low degradability, and low nutrient content [4]. 

Improved management of crop residues enables their efficient utilization as valuable feed resources. One 
important way of achieving protein self-sufficiency for the growing Nigerian population is through enhanced 
utilization of crop residues [5]. Improving the digestibility of poor-quality forages using physical, biological, or 
chemical methods contributes greatly to this goal [6]. 
Physical, biological, and chemical treatments disrupt the bonds between cellulose, hemicellulose, and lignin in plant 
cell walls. This disruption increases the surface area available for microbial attachment, thereby improving 
digestibility [7, 8]. 

The in sacco technique of feed evaluation was developed to enable the routine assessment of different feeds. 
Rumen degradability is commonly determined using this method, which involves incubating feed samples in nylon 
bags placed in the rumen. The in sacco technique is a robust tool widely applied in ruminant nutrition studies [9]. 
It is particularly valuable for describing the degradability characteristics of proteins and other feed fractions in 
forages, as well as in rumen simulation studies [10]. The in-situ method is the most frequently used approach for 
estimating the degradability of dry matter (DM), organic matter (OM), protein, fiber, and other nutrients [11]. 
The rate and extent of DM fermentation in the rumen are critical factors influencing nutrient availability to 
ruminants [12]. 
 

2. Materials and Methods 
2.1. Study Area 

The experiment was conducted at the Laboratory and Research Farm of the Department of Animal Science, 
Bayero University, Kano. The facilities are located at the new site campus of the university, about 13 km from Kano 

metropolis, in Ungogo Local Government Area of Kano State. Kano State lies between longitude 9°30′ and 12°30′ 

East, and latitude 8°42′ and 9°30′ North, within the semi-arid region of northern Nigeria [13]. The state occupies a 

total land area of 24,400 km² [14] with mean annual rainfall ranging from 600 to 1000 mm [15]. The climate is 
characterized by 4–8 months of dry season, with average maximum and minimum temperatures of 33.0°C and 
15.2°C, respectively. 
 

2.2. Experimental Design 
The experiment was laid out in a 3 x 5 factorial arrangement in a completely randomized design, with five (5) 

different additives (Control, Molasses, Sodium hydroxide, Urea, and Yeast) and three ensiling periods (3rd, 5th, and 
7th week). In sacco degradability was laid out in a 3 x 3 switch-over design. 
 

2.3. Ensiling Procedure 
Before ensiling, 31.5 kg of groundnut shells were ground into smaller pieces of about 1 cm using a medium 

crusher with a 2 mm size. Five combinations of groundnut shell, treated with molasses, urea, laboratory yeast, 
sodium hydroxide, and untreated groundnut shell were used. Forty-five bottles were employed, each filled with 
either treated or untreated groundnut shell, compressed using a wooden stick to remove air and tightly closed. 
Grease was applied at the brim to ensure an airtight condition after filling with silage materials and compression. 
Each bottle was replicated three times and divided into three ensilage periods of 3rd, 5th, and 7th weeks, stored 
under shade. At the end of each ensilage period, samples were sun-dried and prepared for chemical analysis and 
degradability studies. 

 An untreated (Control) groundnut shell was prepared by adding 3000 ml of distilled water to 1 kg of 
groundnut shell and ensiling it. Molasses at 5% of groundnut shells was diluted in 3000 ml of water (50 ml of 
molasses was diluted in 3 liters of water to treat 1 kg of GNS) and mixed with groundnut shells. Good silages have 
been reported when molasses is applied at 3-5% [16]. Urea at a level of 2% of groundnut shell was dissolved in 
3000 ml of distilled water (20 g of urea was dissolved in 3 liters of water to treat 1 kg of GNS) and mixed with 
groundnut shell as described in the procedure Roy and Rangnekar [17]. 

Yeast at 1% of groundnut shell was dissolved in 3000 ml of distilled water (10 g of yeast was dissolved in 3 
liters of water to treat 1 kg of GNS) and mixed with groundnut shell as described in the procedure of Gattass et al. 
[18]. Sodium hydroxide at 1% of groundnut shell was dissolved in 3000 ml of distilled water (10 g of NaOH was 
dissolved in 3 liters of water to treat 1 kg of GNS) and thoroughly mixed with groundnut shell. 
 

2.4. Quality Determination of Ensiled Groundnut Shell 
Ensiled materials were opened at the 3rd, 5th, and 7th weeks after ensiling. At opening, pH, colour, and aroma 

were determined, and quality characteristics were assessed according to Babayemi et al. [19]. Immediately after 



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opening, a laboratory thermometer was inserted to determine the temperature. The pH was measured by adding 
100 ml of distilled water to 25 g of each treatment in a beaker, and a pH meter was used to determine the pH. 
Colour and aroma were assessed by descriptive statistics. The conditions were scored for aroma and colour by 
three independent panelists on a scale of 1-4 (Table 1).   
 
Table 1. Description of colour and aroma rating used as indices of silage quality. 

Rating Colour Aroma 

1 Dark or deep brown Putrid or rancid 
2 Light brown Pleasant 
3 Pale yellow Sweet 
4 Yellowish green Very sweet 

Source:  Muhammad, et al. [20]. 

     

2.5. In Sacco Degradability Study 
Degradability study of groundnut shell was carried out using three fistulated Kano Brown bucks with an 

average age of 48 months, according to the nylon bag technique described by Ørskov et al. [21]. The animals were 
given a ten-day period for adaptation to the new feed and housing conditions prior to the suspension of bags. 
Samples were shade-dried and ground through a 2 mm sieve before rumen incubation. Duplicate samples of about 5 

g each were placed in nylon bags (bag size 80 mm x 140 mm; pore size 45 μm) and suspended in the rumen of three 
fistulated bucks for 8, 12, 18, 24, 36, and 48 hours as outlined by Ørskov and McDonald [22].  

After removal from the rumen, the bags were immediately dipped into cold water to stop microbial activity, 
then washed under running water to remove rumen contents from the outside of the bags. They were subsequently 
rinsed for 30 minutes to ensure thorough cleaning. Zero-hour samples were prepared by washing the bags 
containing test samples for 30 minutes without rumen incubation. The residues remaining in the bags were oven-
dried at 60°C for 48 hours, following the procedure of Nocek [23]. The bags were then cooled, weighed, and the 
data obtained were used to calculate the percentage dry matter loss. The results from the in sacco study were fitted 
to the model of Ørskov and McDonald [22] (P = a + b (1 – e^(-ct))) to determine the degradation characteristics of 
the incubated samples. 
Where, 

P = Potential degradability after time ‘t’. 
a = Water Soluble Fraction (Zero hour). 
b = Insoluble but degradable fraction after time ‘t’. 
c = Rate of degradation of the slowly degradable fraction b. 
t = Incubation length, i.e. 8, 12, 18, 24, 36, and 48 hrs. 
e = exponential. 

 

2.6. Statistical Analysis 
Descriptive statistics were used to assess silage quality. For in sacco data, analysis of variance (ANOVA) was 

performed using the General Linear Model procedure of SPSS (SPSS Version 21.0). Differences among means were 
separated using LSD at a 95% probability level. 
 

2.7. Chemical Composition of Groundnut Shell 
Samples ensiled (GNS) were analyzed for proximate composition (CP, CF, EE, DM, Nitrogen-free extract and 

Ash) according to procedures of AOAC (Association of Official Analytical Chemists) [24]. Neutral detergent Fibre 
(NDF) and acid detergent Fibre (ADF) were determined according to procedures outlined by Van Soest and 
Robertson [25].  
 

3. Results and Discussion 
3.1. Results 
3.1.1. Effects of Additives on Groundnut Shell Silage Characteristics 

The result of additives on GNS characteristics is shown in Table 2. The pH values ranged from 5.63 – 3.87 and 
there was a significant (p<0.05) difference among the treatments. The silage made with NaOH had a higher pH 
value (5.63), while the lowest value was recorded in yeast treatments. The silage treated with additives had pH 
values less than 6.0. 
 
Table 2. Effects of additives on groundnut shell silage characteristics. 

Parameter 

Treatment Ph Colour Aroma 

Untreated GNS 4.67b Light brown Pleasant 
Urea+GNS 4.55b Pale yellow Sweet 
Yeast+GNS 3.87c Pale yellow Sweet 
Molasses+GNS 4.55b Pale yellow Sweet 
NaOH+GNS 5.63a Light brown Pleasant 
SEM 0.043 - - 
Note: Means with different superscripts (a, b, c) within the same column are significantly different (P<0.05). 

   

3.1.2. Effect of Ensiling Period on Groundnut Shell Silage Characteristics 
The results of the ensiling period on GNS silage characteristics are presented in Table 3. The pH values of 

silages were significantly affected (P<0.05) by the ensiling period. The pH values ranged from 4.39 at 7 weeks, 4.58 
at 5 weeks, and 4.98 at 3 weeks. In terms of colour and aroma, all silage produced at different periods was light 
brown with a pleasant aroma at 3 weeks, and pale yellow with a sweet aroma at 5 and 7 weeks, respectively. 



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Table 3. Effects of ensiling period on groundnut shell silage characteristics. 

Parameter 

Period   pH Colour Aroma 

Week 3 4.98a Light brown Pleasant 
Week 5 4.58b Pale yellow Sweet 
Week 7 4.39c Pale yellow Sweet 
SEM 0.033     -    - 
Note: Means with different superscripts (a, b, c) within the same column are significantly different (P<0.05). 

 

3.1.3. Interaction Effect of Additives and Ensiling Period on Groundnut Shell Silage Characteristics 
Results of additives and the ensiling period on GNS silage characteristics are shown in Table 4. The result 

revealed that urea and yeast GNS treatment had a pale yellow colour with a sweet aroma. Control and yeast 
treatment had a combination of both pale yellow and light brown colours with a sweet and pleasant aroma in all the 
periods of ensiling. Meanwhile, sodium hydroxide had a light brown colour with a pleasant aroma and a pH range 
of 3.62–5.21 across all treatments and periods of ensiling. 

 
Table 4. Interaction effects between additives and ensiling period of groundnut shell (GNS) silage characteristic. 

Parameters 

Treatments Period pH Colour Aroma 

Untreated GNS 3 4.66 Light brown Pleasant 
5 4.73 Light brown Pleasant 
7 4.62 Pale yellow Sweet 

Urea+GNS 3 4.59 Pale yellow Sweet 
5 4.55 Pale yellow Sweet 
7 4.50 Pale yellow Sweet 

Yeast+GNS 3 4.16 Pale yellow Sweet 
5 3.38 Pale yellow Sweet 
7 3.62 Pale yellow Sweet 

Molasses+GNS 3 4.72 Light brown Pleasant 
5 4.72 Pale yellow Sweet 
7 4.20 Pale yellow Sweet 

NaOH+GNS 3 5.21 Light brown Pleasant 
5 5.10 Light brown Pleasant 
7 5.03 Light brown Pleasant 

SEM  0.075   
T X P  * - - 

Note: T x P = Treatment x period interaction. 

 

3.1.4. Effect of Additives on Chemical Composition of Groundnut Shell Silage 
The results of additives on the chemical composition of GNS silage are shown in Table 5.  
The result revealed that there was a significant (p<0.05) difference among all the parameters evaluated. 

Percent Dry Matter (DM) of silage made from GNS (control) has the highest value of 92.60%, while the lowest 
value of 90.77% was recorded from the silage made from GNS (yeast). Treatment (urea) had the highest crude 
protein (CP) content at 8.97%, and the lowest CP at 4.33% was recorded in the control, followed by NaOH. Crude 
fibre (CF) was higher in the control at 51.42%, while the lowest value of 33.71% was recorded from silage made 
from GNS (urea). The treatment with yeast and molasses had the highest value of NFE, and the lowest value was 
recorded in the control. The lowest value of Acid Detergent Fibre (ADF) was recorded in the urea treatment, while 
the highest ADF was in the control. The lowest Neutral Detergent Fibre (NDF) was recorded in the urea 
treatment, and the highest NDF was in the control. 
 
Table 5. Effects of additives on chemical composition (%) of groundnut shell silage. 

Parameters 

Treatment DM Ash CP CF EE NFE ADF NDF 

Untreated GNS 92.60a 4.78b 4.33c 51.42a 0.99d 38.45d 57.71a 75.04a 
Urea+ GNS 90.89b 5.45a 8.97a 33.71d 3.41c 39.36c 41.25d 65.19d 
Yeast+ GNS 90.77bc 4.59c 7.15b 39.49c 4.88a 43.90a 52.09b 71.39b 

Molases+GNS 90.86c 3.91d 7.01b 46.88b 3.71b 42.58b 46.19 b 72.29b 
NaOH+GNS 90.81bc 3.91d 7.00b 47.88b 3.64b 38.47d 43.23b 67.24c 

SEM 0.032 0.37 0.210 0.157 0.063 0.204 0.427 0.431 
Note: Means with different superscripts (a, b, c, d) within the same column are significantly different (P<0.05).  

DM: Dry matter, CP: Crude protein, CF: Crude fibre, EE: Ether extract, NFE: Nitrogen free extract, ADF: Acid detergent fibre, NDF: Neutral 
detergent fibre. 

 

3.1.5. Effect of Ensiling Period on Chemical Composition of Groundnut Shell Silage 
The effects of the ensiling period on chemical compositions of GNS silage are shown in Table 6. The 

parameters evaluated are DM, ASH, CP, CF, EE, NFE, ADF, and NDF, and they were all significant (p<0.05) at 
all the ensiling periods. The DM percentage was highest at the 3rd week of the ensiling period (91.35%) compared 
to the 5th and 7th weeks, respectively. Ash content was highest at the 7th week (5.26%) and lowest at the 3rd week 
(3.84%). Crude protein (CP) content was highest at the 7th week (7.35%), while the lowest CP content was observed 
at the 3rd week (6.50%). Crude fiber (CF) content was highest at the 3rd week (47.36%) and lowest at the 7th week of 
the ensiling period (40.26%). 
 
 
 
 



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Table 6. Effects of ensiling period on chemical composition (%) of GNS-treated silage. 

Parameter 

Period    DM Ash CP CF EE NFE ADF NDF 

Week 3 91.35a 3.84a 6.50b 47.36a 2.78c 37.84b 72.06a 67.81a 
Week 5 91.24a 4.52b 6.82b 43.41b 3.03b 41.95a 70.88b 74.80b 
Week 7 91.06b 5.26c 7.35a 40.26c 4.17a 41.87a 68.06b 71.46c 

SEM 0.025 0.028 0.163 0.122 0.49 0.158 0.334 1.040 
Note: Means with different superscripts (a, b, c) within the same column are significantly different (P<0.05).   

DM: Dry matter, CP: Crude protein, CF: Crude fibre, EE: Ether extract, NFE: Nitrogen-free extract, ADF: Acid detergent fibre, NDF: Neutral 
detergent fibre. 

 

3.1.6. Interaction between Additives and Ensiling Period on Chemical Composition of Groundnut Shell Silage 
The effect of interaction between additives and the ensiling period on the chemical composition of GNS silage 

is shown in Table 7. Additives and the ensiling period significantly affect the chemical composition of silage. The 
percentage of dry matter (DM) in silage made without additives (control) at the 3rd week of the ensiling period was 
highest at 92.74%, while at the 7th week, yeast-treated silage had the lowest DM content at 90.57%. The percentage 
of ash shows an increasing trend as the ensiling period progresses, with the highest value recorded at the control at 
week 7 and the lowest at molasses at week 3. The crude protein (CP) content was highest in urea-treated silage at 
the 7th week, reaching 9.58%, and lowest in the control at 3.50% during the same period. The lowest crude fiber 
(CF) interaction was observed in urea at week 7, at 29.14%. The highest ether extract was found in yeast-treated 
silage at week 7, at 5.67%, while the lowest was in the control at week 3, at 0.45%. The nitrogen-free extract (NFE) 
was highest in molasses at week 7, at 45.94%, and lowest in the control at week 7, at 36.28%. These findings 
highlight the influence of different additives and the duration of ensiling on the chemical composition of silage, 
which is crucial for optimizing feed quality and nutritional value. The interaction between additives and ensiling 
period on the chemical composition of GNS was significantly (p<0.05) different for all parameters evaluated. 

 
 7. Interaction effects between additives and ensiling period on chemical composition (%) of groundnut shell silage. 

Parameters 

Treatment Period DM ASH CP CF EE NFE ADF NDF 

Untreated GNS  3 92.74 3.72 3.50 54.00 0.45 37.63 59.42 75.19 
5 92.56 4.33 4.20 51.19 0.62 40.29 57.93 76.40 
7 92.52 6.34 5.29 49.05 1.89 36.28 55.77 73.54 

Urea +GNS  3 90.98 4.61 8.44 39.37 2.28 37.42 59.71 69.14 
5 90.94 5.61 8.88 32.66 3.64 40.21 32.41 64.27 
7 90.75 6.13 9.58 29.14 4.31 41.58 31.60 62.18 

Yeast +GNS  3 90.81 4.18 7.24 43.26 4.18 42.03 57.23 76.39 
5 90.92 4.43 7.38 38.15 4.78 45.29 45.37 73.64 
7 90.57 5.15 8.02 37.08 5.67 44.30 53.66 68.35 

Molasses + GNS  3 90.96 3.34 6.34 50.07 3.15 36.92 47.17 72.66 
5 90.92 4.12 6.72 47.55 3.49 44.48 46.09 73.81 
7 90.69 4.33 7.07 43.04 4.48 45.94 45.32 69.88 

NaOH + GNS 3 90.93 4.21 7.18 47.55 3.95 38.00 44.41 67.78 
5 90.92 4.32 7.08 43.04 4.48 41.68 41.93 65.51 
7 90.76 4.46 7.28 42.21 5.24 38.03 53.63 68.08 

SEM  0.055 0.633 0.364 0.273 0.109 0.354 0.740 0.747 
T X P  * * * * * * * * 

Note:  T= Treatment x period interaction, 3= Weeks 3, 5= Weeks 5, 7= Weeks 7. 

 

3.1.7. Dry Matter (DM) Disappearance (%) of Untreated Groundnut Shell 
The results of dry matter disappearance of untreated GNS at different ensiling period is presented in Figure 1. 

The untreated GNS disappearance curve revealed that the 7th week silage had the greatest disappearance values 
during 0-48 hours of incubation, followed by the 5th week, and finally, the least was the 3rd week silage. 
 

 
Figure 1. Dry matter disappearance (%) of untreated groundnut shell. 

 



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3.1.8. Dry Matter (DM) Disappearance (%) of Urea Treated Groundnut Shell 
The results of dry matter disappearance of urea treated GNS are shown in Figure 2. The urea dry matter curve 

revealed that GNS treated with urea and ensiled at 7th week produced slightly higher DM disappearance values 
after a 48-hour incubation period, followed by the 5th week, and the least was at the 3rd week ensiling period. 

 

 
Figure 2. Dry matter disappearance (%) of groundnut shell treated with urea. 

 

3.1.9. Dry Matter Disappearances (%) of Groundnut shell Treated with Yeast 
Figure 3 the analysis revealed that GNS treated with yeast at the 7th week exhibited the highest dry matter 

(DM) disappearance, followed by the 5th week, while the lowest was recorded at the 3rd week ensiling period after a 
48-hour incubation period. 

 

 
Figure 3. Dry matter disappearance (%) of groundnut shell treated with yeast. 

 

3.1.10. Dry Matter Disappearance (DM) of Groundnut Shell Treated with Molasses 
The results of dry matter disappearance of molasses treated GNS at different ensiling period are shown in 

Figure 4. The dry matter disappearance curve revealed that molasses-treated GNS at 7th weeks produced the 
greatest DM disappearance after 48 hours, followed by 5th weeks, and the least was at three weeks after the 48-
hour incubation period. 
 



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Figure 4. Dry matter disappearance (%) of groundnut shell treated with molasses. 

 

3.1.11. Dry Matter Disappearance (DM) of Groundnut shell Treated with NaOH 
The results of dry matter disappearance of NaOH treated GNS at different ensiling period are shown in Figure 

5. The dry matter disappearance curve revealed that NaOH-treated GNS at 7th weeks produced the greatest DM 
disappearance after 48 hours, followed by 5th weeks, and the least was at three weeks after the 48-hour incubation 
period. 
 

 
Figure 5. Dry matter disappearance (%) of groundnut shell treated with NaOH. 

 

3.1.12. Effect of Additives on Dry Matter Degradability of Groundnut Shell Silage 
 The results of the rumen degradation characteristics of treated and untreated GNS silage are shown in Table 

8. Groundnut shell shows no significant difference (p>0.05) between treatments. The results indicate that yeast has 
a higher quickly soluble fraction ‘a’ (45.55), while urea has a higher ‘b’ slowly degradable fraction (328.79). The 
degradation rate constant ‘c’ was higher in the control (0.048) and lower in yeast and molasses (0.002). The highest 
potential degradability (PD) was recorded in yeast (100%), and the lowest was in NaOH (88.61%). 

The highest effective degradability (ED2, ED5, and ED8) was recorded in molasses (67.50%, 53.17%, and 
48.81%, respectively), and the lowest was obtained in the control (54.07%, 44.78%, and 41.58%, respectively). 
 
Table 8. Effect of additives on dry matter degradation characteristics of groundnut shell silage. 

Parameters 

Treatments  A b C A B PD ED2 ED5 ED8 

Untreated GNS 29.27 189.98 0.048 28.77 66.24 95.03 54.07 47.54 41.58 
Urea + GNS 31.33 328.79 0.041 32.43 66.70 99.14 59.88 44.78 46.07 
Yeast + GNS  45.55 271.32 0.041 30.18 69.81 100.00 57.74 49.58 46.73 
Molasses+ GNS  23.58 286.82 0.002 35.42 54.61 90.67 67.50 53.17 48.81 
NaOH + GNS 9.52 295.19 0.002 30.92 57.71 88.61 59.70 47.64 44.24 
 SEM 15.76 123.17 0.028 1.379 4.453 4.267 1.99 3.05 3.22 

Note: Means with different superscripts within the same column are significantly different (P<0.05). a- quickly soluble fraction; b- slowly degradable 
fraction; c- degradation rate constant (Fraction/Hour); A- washing lost, B- rumen degradability fraction, PD- potential degradability; ED- effective 
degradability (%). 



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3.1.13. Effect of Ensiling Period on Dry Matter (DM) Degradation Characteristics of Groundnut Shell Silage 
The results of the effects of the ensiling period on DM degradation characteristics are presented in Table 9. 

The results revealed that no significant difference was observed for all the parameters evaluated. From the results 
obtained, period 7 had a higher value of the ‘a’ quickly soluble fraction; the ‘b’ slowly degradable fraction was 
higher at period 5, while the ‘c’ degradation rate constant was higher at period 3. The potential degradability (PD) 
obtained at the 7th week was higher (99.15%) compared to the 3rd and 5th weeks (92.25% and 92.67%, respectively). 

 
Table 9. Effect of ensiling period on dry matter (DM) degradation characteristics of groundnut shell silage. 

Period   Parameters 

a B C A B PD ED2 ED5 ED8 

Week 3  6.81 230.46 0.054 33.53 58.55 92.25 56.64 44.77 41.04 
Week 5  43.68 400.94 0.003 29.13 63.32 92.67 60.87 50.17 46.96 
Week 7  33.18 311.85 0.026 32.00 67.18 99.15 61.83 48.72 44.87 
SEM 12.204 95.413 0.022 1.068 3.449 3.305 1.546 2.360 2.498 
Note: Means with different superscripts within the same column are significantly different (P<0.05). a- quickly soluble fraction; b- slowly degradable 

fraction; c- degradation rate constant (Fraction/Hour); A- washing lost, B- rumen degradability fraction, PD- potential degradability; ED- effective 
degradability (%); 

 

3.1.14. Interaction Effect between Additives and Ensiling Period on Dry Matter Degradation Characteristics of 
Groundnut Shell Silage 

Table 10 presents the interaction effects between additives and ensiling period on the dry matter (DM) 
degradation characteristics of groundnut shell silage. The results show that neither additives nor the ensiling 
period significantly affected parameters a, b, or c across treatments. However, urea- and yeast-treated silages at 7 
weeks generally exhibited higher potential degradability (PD = 100%) compared to other treatments, while 
molasses-treated silage showed the highest effective degradability (ED2, ED5, and ED8). These findings suggest 
that treatment type and storage duration influence degradability patterns, with urea and yeast improving potential 
degradability and molasses improving effective degradability. 

 
Table 10. Interaction effect between additives and ensiling period on dry matter degradation characteristics of groundnut shell silage 

Treatment Period a B c A B PD ED2 ED5 ED8 

Untreated GNS 
  

3 30.00 348.59 0.001 26.37 73.63 100 54.08 40.03 36.37 
5 36.67 113.04 0.006 32.77 52.33 85.10 53.17 43.86 41.20 
7 21.15 108.31 0.125 27.23 72.77 100 54.97 49.53 47.17 

Urea + GNS 3 50.19 164.41 0.141 22.07 66.67 100 51.53 43.73 40.97 
5 39.39 323.71 0.002 29.33 70.47 100 63.07 49.33 45.70 
7 39.36 397.48 0.001 27.10 72.90 100 64.50 49.87 46.07 

Yeast +GNS 3 35.31 229.84 0.003 38.43 61.57 100 63.33 47.43 43.07 
5 31.27 357.04 0.002 22.07 75.34 100 54.87 41.13 37.46 
7 28.00 399.46 0.002 36.80 63.20 100 61.47 45.06 39.70 

Molasses + GNS 3 10.23 162.67 0.119 34.53 49.83 85.33 59.23 51.63 47.93 
5 41.16 244.76 0.003 36.87 48.73 86.33 70.50 53.93 49.50 
7 39.80 453.04 0.002 34.87 65.27 100 72.76 53.97 49.00 

NaOH + GNS 3 29.15 246.81 0.006 34.37 41.63 75.93 55.03 41.00 36.87 
5 69.93 966.19 0.005 24.40 69.73 94.13 62.73 62.60 60.93 
7 37.58 200.95 0.002 34.00 61.77 95.76 55.47 45.17 42.40 

SEM  27.28 213.35 0.05 2.39 7.71 7.39 3.46 5.28 5.58 
Note: Means with different superscripts within the same column are significantly different (P<0.05). a- quickly soluble fraction; b- slowly degradable 

fraction; c- degradation rate constant (Fraction/Hour); A- washing lost, B- rumen degradability fraction, PD- potential degradability; ED- effective 
degradability (%). 

 

3.2. Discussion 
pH is widely used as a simple indicator of silage quality, with well-fermented silages typically exhibiting low 

pH values. Kung and Shaver [26] reported that tropical grass and legume silages generally have pH values 
ranging between 4.3 and 4.7. In this study, the pH of groundnut shell (GNS) silage decreased with increasing 
ensiling duration, reflecting progressive fermentation. Sodium hydroxide treated silage maintained a relatively 
higher pH (5.21), which agrees with Henderson et al. [27]. In contrast, urea-, yeast-, and molasses-treated silages 
had lower pH values (3.62–5.21), indicating effective fermentation and good preservation quality. 

The colour and aroma of GNS silage further supported these findings. All silages appeared pale yellow to light 
brown, with pleasant or sweet odours. According to Kung and Shaver [26] a sweet aroma is an indicator of well-
fermented silage, while Oduguwa et al. [28] emphasized that silage resembling the original forage colour and 
having a pleasant smell reflects desirable fermentation. These observations suggest that additives contributed 
positively to the physical quality of GNS silage. 

Proximate composition results revealed slight variations across treatments, which may be attributed to 
differences in additives, crop variety, cultivation methods, and environmental factors, as previously noted by Larbi, 
et al. [29]. Untreated silages recorded higher dry matter (DM) content than treated silages, possibly due to 
reduced fermentation losses [30]. Urea and yeast treatments resulted in significantly higher crude protein (CP) 
contents, consistent with earlier studies demonstrating that ammoniation enhances protein levels in crop residues 
[31, 32]. In contrast, crude fibre contents decreased with urea, yeast, molasses, and NaOH treatments, supporting 
the view that these additives disrupt lignocellulosic bonds, thereby improving digestibility [33]. 

The fibre fractions (ADF and NDF) of GNS silage also declined with additive treatment and longer ensiling 
periods. This observation is in agreement with Tadesse et al. [34], who reported reductions in fibre fractions of 
ensiled crop residues following chemical and biological treatment. Such reductions suggest improved availability of 
nutrients for microbial fermentation in the rumen. 



Agriculture and Food Sciences Research, 2025, 12(2): 100-109 

108 
© 2025 by the authors; licensee Asian Online Journal Publishing Group 

 

 

The in sacco degradability trial demonstrated that both the ensiling period and additives influenced the 
degradability characteristics of GNS. Dry matter (DM) disappearance rates increased with longer incubation times, 
with the highest degradability observed after 48 hours of rumen incubation. Urea- and yeast-treated silages ensiled 
for 7 weeks showed markedly higher potential degradability (100%), indicating that these treatments improved 
rumen breakdown of the silage. Molasses-treated silages, however, recorded the highest effective degradability 
across different passage rates, suggesting that molasses enhanced the readily fermentable fraction of the silage. 

These findings are consistent with reports by Ørskov and McDonald [22] who highlighted the usefulness of 
the in sacco method in estimating degradability parameters. Similar improvements in degradability following urea 
treatment have also been reported in crop residues such as maize stover and wheat straw [35]. Yeast 
supplementation has likewise been associated with increased microbial activity and improved fibre utilization [36]. 
The present results confirm that biological and chemical additives can significantly enhance the degradability of 
groundnut shell, a by-product that is otherwise poorly utilized in animal feeding. 

Overall, the study demonstrates that both the ensiling period and additive type influence the fermentation 
quality, proximate composition, and degradability characteristics of GNS silage. Urea and yeast were most effective 
in improving crude protein and potential degradability, particularly after 7 weeks of ensiling, while molasses 
improved effective degradability. These findings suggest that groundnut shell, when properly treated and ensiled, 
can serve as a valuable feed resource for ruminant production. 
 

4. Conclusion 
This study demonstrated that both additive type and ensiling duration significantly influence the fermentation 

quality, proximate composition, and degradability of groundnut shell silage. Urea and yeast treatments produced 
the highest crude protein contents and markedly improved potential degradability, particularly after seven weeks 
of ensiling. Molasses treatment enhanced effective degradability, while sodium hydroxide maintained higher pH 
values. Overall, the results confirm that groundnut shell, a widely available agricultural by-product, can be 
transformed into a valuable ruminant feed resource when properly ensiled with suitable additives. 
 
4.1. Recommendations 

Based on the results and drawbacks of this research work, the following recommendations are made: Silage 
made from urea or yeast ensiled at the 7th week period is recommended for feeding farm animals. Further 
investigation needs to be conducted using feeding trials with groundnut shell ensiled with urea or yeast. 

 

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