197 Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016
Feeding value of cassava products supplemented with
earthworm meal in diets of growing rabbits
O.O.Kuforiji, J.A.Agunbiade, H.A.Awojobi* and O.O.Eniolorunda
Department of Animal Production, Olabisi Onabanjo University
Yewa Campus, P.M.B 0012, Ayetoro, Ogun State, Nigeria
*Corresponding Author E-mail: [email protected]
An eight week feeding trial was conducted to evaluate the effect of earthworm meal supplementation in various cassava
based products in growing rabbit diets. Nine isocaloric and isonitrogenous diets were formulated such that each diet
contained a constant amount of Soybean Meal, SBM (50%) and Cassava Leaf Meal, CLM (25%) as part of the protein
component. The remaining 25% protein of animal origin was supplied by Fish Meal (FM) and Earthworm Meal (EWM) in
varying proportions as follows: Diet 1 (100% whole cassava root meal (WCRM), 12.5% FM protein, 12.5% EWM protein);
Diet 2 (50% WCRM, 50% cassava peel meal (CPM), 12.5% FM protein, 12.5% EWM protein); Diet 3 (50% WCRM, 50%
cassava chaff meal (CCM), 12.5% FM protein, 12.5% EWM protein); Diet 4 (25% WCRM, 75% CPM, 12.5% FM protein,
12.5% EWM protein); Diet 5 (25% WCRM, 75% CCM, 12.5% FM protein, 12.5% EWM protein); Diet 6 (50% WCRM,
50% CPM, 6.25% FM protein, 18.75% EWM protein); Diet 7 (50% WCRM, 50% CCM, 6.25% FM protein, 18.75% EWM
protein); Diet 8 (25% WCRM, 75% CPM, 6.25% FM protein, 18.55% EWM protein); Diet 9 (25% WCRM, 75% CCM,
6.25% FM protein, 18.55% EWM protein). Twenty seven (27) growing rabbits of mixed breeds and sexes were allotted to
the nine dietary treatments such that each was replicated three times and were fed and watered ad libitum. Data collected
included feed intake, weight gain, feed conversion ratio, as well as carcass characteristics, organ weights and gut dimension.
Results showed that feed intake was not significantly (P>0.05) affected by dietary treatments but weight gain and FCR were
both enhanced (P<0.05). Treatment effects on carcass characteristics, organ weights and gut dimensions were not
significant. The results suggested that EWM protein can replace 50% of FM protein in rabbit diets without any adverse
effects.
Keywords: Cassava products, growing rabbit, performance, carcass characteristics, fish meal, earthworm meal
Rabbits are efficient converters of feed to meat
and can utilize up to 30% crude fiber as against
10% by most poultry species (Egbo et al.
2001). Its meat which is white is high in quality
protein with low fat and cholesterol levels;
hence it is good for those with fat related
diseases like hypertension (Nodu et al. 2003).
Rabbit also has a reproductive potential that is
legendary. Despite the advantages enumerated,
studies on the production system showed that
other factors affect it, especially feeding,
which is the major limiting factor in achieving
optimal performance in rabbit. Although
rabbits do survive on forage pasture alone,
because of their limited forage utilization, it
was suggested that for maximum productivity
conventional feed should be used (Onwudike
1995). However the high cost of the feed
ingredients and the poverty level among the
citizenry call for alternative sources of
ingredient than the conventional ones. For
example, maize grain which is the main source
of carbohydrate and metabolisable energy in
conventional feed is a seasonal crop which is
in high demand by other sectors of the
economy either as food for human
consumption or industrial raw material for
production purposes. This high demand is
responsible for high cost of maize. There is
therefore need for an alternative source of
energy which would be cheaper, readily
available all year round and less competitive.
The search for this has led to discovery of
suitable alternatives, which include cassava
and its by products. Nigeria is ranked as the
highest producer of cassava in the world
producing around 34 million tonnes (FAO
2002). Most of the cassava produced is mainly
used for human consumption with little left for
processing. Furthermore, the Federal
government of Nigeria has effected legislation
that all flour mills must have a 10% inclusion
of cassava flour in all wheat flour that enters
the Nigerian market with effect from 1st July
0041-3216/2016/030197-12 © 2016 Trop. Agric. (Trinidad)
Cassava products with earthworm meal supplementation for rabbit feeding; O.O. Kuforiji et al
Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016 198
2006. The implication of this is that about
200,000 metric tonnes of unfermented cassava
will be required annually since about 2 million
metric tonnes of wheat flour is released into
Nigeria market by the currently operational 27
flour mills in the country. Because of the recent
government interest in cassava production, this
might make cassava peel and chaff, which are
often discarded during cassava processing into
“Fufu”, “Gari” and other cassava products,
suitable energy sources for non ruminant feed
in place of cassava root meal. Cassava starchy component compares
favorably with that of maize but at a much reduced price, cassava also has the singular advantage of good yield on poor soil as it can withstand drought better, thus making it a more suitable alternative source of livestock feed (IITA 2005). Cassava products are low in protein, amino acids and other nutrients and therefore they are used mainly as sources of energy. Hence the need to supplement cassava products with additional protein sources (Agunbiade et al. 2002). The animal protein source should not be expensive as in conventional feeds since it has been reported that protein, especially fish meal, is the most expensive feed stuff in animal feed formulation (Yaqub 1997). Other alternative sources of protein, such as shrimp waste meal had been successfully incorporated into broiler diets at various level of substitution for fishmeal (Agunbiade et al. 2004; Okonkwo et al. 2007). Cassava based feed product can also be cheaply fortified with cassava leaf meal as reported by Agunbiade and Susenbeth (2006). Other research findings have shown the replacement of fish meal with hatchery waste as reported by Agunbiade et al. (2007) for broiler finisher diets but the current work focuses on use of earthworm meal as replacement for fish meal at certain graded levels.
The challenge was to formulate rations for grower rabbits with the energy content supplied by maize replaced by whole cassava root, cassava chaff (cassava sievate) and cassava peel while improving on the amino
acid content and additional source of protein to improve the nutritional value of the diet by using earthworm meal. The objectives of the study are: 1. To determine the effect of earthworm meal
in combination with cassava chaff and peel on the performance of grower rabbits.
2. To evaluate the effect of the feeds on carcass composition, organ weights and gut dimensions.
3. To undertake a cost evaluation of the use of earthworm meal supplemented cassava products based diets for rabbit.
Materials and methods Study location The experiment was conducted at the Teaching and Research Farm, College of Agricultural Sciences, Olabisi Onabanjo University, Yewa Campus, Ayetoro, Ogun State, Nigeria. The university campus is located in a deciduous/derived savannah zone of Nigeria at latitude 7o 15’N and longitude 3o 3’E. Climate is sub-humid tropical with an annual rainfall of 1,909.3mm. Rainy season is between early April and late October. Rainfall pattern is bimodial with two peaks in June and September. Maximum temperature varies between 29oC during the peak of the wet season and 340C at the onset of the wet season and mean annual relative humidity is 81% (Onakomaiya et al. 1992).
Test materials To obtain the Whole Cassava Root Meal (WCRM), cassava roots were washed with clean water to free them from soil debris. They were sliced with peel intact and then sun dried until practical dryness was achieved after seven days. The dried whole cassava was then milled to pass through a 2.00 mm screen and bagged, as whole cassava root meal.
Fresh cassava leaves were harvested
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199 Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016
without the petioles and chopped into small sizes before wilting overnight. The wilted leaves were sun dried until dryness was achieved after four days. The leaves were milled to obtain Cassava Leaf Meal (CLM).
Fresh cassava peel and cassava chaff were obtained from “fufu” processing centers. Each was separately sun dried until dryness was achieved after five sunny days. The peels and the chaff were separately milled with hammer mill of particle size of 2.0 mm screen to obtain Cassava Peel Meal (CPM) and Cassava Chaff Meal (CCM) respectively.
Earthworm Meal (EWM) was prepared in batches as they were collected daily from soil in the university community and river banks in the environs. Each batch of earthworms collected was first washed with clean water and placed on sieve mesh of size 5.00 mm on top of a tray in the sun. The earthworms moved through the mesh into the trays away from the sun, after which they were washed again to free them from as much soil debris as possible. They were then blanched on a cooking stove for three minutes to immobilize them and render them tender for easy digestibility. The blanched worms were then sun-dried to dryness and milled and bagged as earthworm meal.
Other ingredients like soybean meal (SBM), fish meal (FM), wheat offal (WO), bone meal (BM), vitamins and mineral premixes, vegetable oil and salt were bought from feed millers. The materials were stored in a cool dry place before mixing.
Experimental diets
Nine experimental diets (Table 1) were
formulated to be isocaloric and isonitrogenous
in composition with a basal diet as the control
and the other eight diets contained proportions
of the basal diet and varying portions of
earthworm meal protein replacing the fish
meal protein as shown below:
Diet 1 was the control diet consisting of
100% WCRM as the major source of
energy, 50% SBM, 25% CLM protein,
12.5% FM protein and 12.5% EWM
protein.
Diet 2 consisted of 50% WCRM, 50% CPM,
50% SBM protein, 25% CLM protein,
12.5% FM and 12.5% EWM protein.
Diet 3 consisted of 50% WCRM, 50% CCM,
50% SBM protein, 25% CLM protein,
12.5% FM protein and 12.5% EWM
protein.
Diet 4 consisted of 25% WCRM, 75% CPM,
50% SBM protein, 25% CLM protein,
12.5% FM protein and 12.5% EWM
protein.
Diet 5 consisted of 25% WCRM, 75% CCM,
50% SBM protein, 25% CLM protein,
12.5% FM protein and 12.5% EWM
protein.
Diet 6 consisted of 50% WCRM, 50% CPM,
50% SBM protein, 25% CLM protein,
6.25% FM protein and 18.75% EWM
protein.
Diet 7 consisted of 50% WCRM, 50% CCM,
50% SBM protein, 25% CLM protein,
6.25% FM protein and 18.75% EWM
protein.
Diet 8 consisted of 25% WCRM, 75% CPM,
50% SBM protein, 25% CLM protein,
6.25% FM protein and 18.75% EWM
protein.
Diet 9 consisted of 25% WCRM, 75% CCM,
50% SBM protein, 25% CLM protein,
6.25% FM protein and 18.75% EWM
protein.
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Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016 200
Table 1: Composition (g/kg) of experimental diets
Ingredient 1 2 3 4 5 6 7 8 9 WCRM 470 235.0 235.0 117.5 117.5 235.0 235.0 117.5 117.5 CPM - 235 - 352.8 - 235.0 - 352.8 - CCM 235.0 - 352.5 - 235.0 - 352.5 - 352.5 SBM 160 160 160 160 160 160 160 160 160 CLM 160 160 160 160 160 160 160 160 160 WO 86 86 86 86 86 86 86 86 86 FM 24 24 24 24 24 12 12 12 12 EWM 30 30 30 30 30 42 42 42 42 Veg Oil 25 25 25 25 25 25 25 25 25 BM 30 30 30 30 30 30 30 30 30 OS 5 5 5 5 5 5 5 5 5 Salt 5 5 5 5 5 5 5 5 5 Premix 5 5 5 5 5 5 5 5 5 WCRM= Whole Cassava Root Meal CPM= Cassava Peel Meal CCM= Cassava Chaff Meal CLM = Cassava Leaf
Meal SBM= Soyabean Meal WO= Wheat Offal FM= Fish Meal EWM= Earthworm Meal Veg Oil= Vegetable Oil
BM = Bone Meal OS = Oyster shell. Premix containing per kg diet: Vit. A 3.2 × 106 I.U; Vit.D 8.0 × 105 I.U; Vit. E
4 × 103 I.U; Vit. B1 400mg; Vit. B2 800mg; Vit. B3 300mg; B6 400mg; B12 3mg; Niacin 600mg; Panthothenic
acid1000mg; Folic acid 140mg; choline chloride 5.75 × 104 mg; Zinc 1.6 × 105 mg; Co 85mg; Mn 200mg; Ethoxyquine
650mg.
Experimental Animals
A total of twenty seven (27) rabbits of mixed
breeds (reciprocal crosses of New Zealand
White and Chinchilla) and sexes were
procured for the experiment. The animals were
placed on the same proprietary rabbit growers
mash until two weeks before the
commencement of the experiment. They were
weighed and randomly distributed into nine
groups (dietary treatments), adjustments were
made for weights and sexes within each group
having a total of three rabbits. The animals
were housed individually in three two-tier
cages (60cm x 30cm x 50cm). The animals
were fed recorded quantities of the
experimental diets daily for a two-week
preliminary period in order to adapt the
animals to the various ingredients in the
experimental diets.
Experimental Procedure
The various experimental diets were fed to the
rabbits for a period of eight weeks. During this
period feed and cool fresh water were provided
ad libitum. Feed for each day was given twice
(008-009h and 017-018h).The quantities of
feed given were measured daily while weight
gains were recorded on a weekly basis. At the
end of the experiment all the rabbits were
slaughtered by severing the jugular veins after
stunning. The skin of the rabbits was removed
and evisceration done.
Data Collection
Daily feed intake, weekly live weight changes
and Feed Conversion Ratio (FCR) expressed
as grammes feed consumed per gramme
weight gain were calculated.
Slaughter records were kept on wholesale
cuts (shoulder, loin, rack and thigh) by
products (head, wet skin, legs and gut) as well
as the visceral organs (heart and liver). These
were weighed separately and various gut
dimensions considered and recorded. The
dressing percentage of rabbits in each
treatment was calculated as: Dressing % = Dressed weight / Live weight × 100
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201 Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016
Proximate and Chemical Analysis
The oven-dried samples of feed were analysed
for residual moisture, crude protein, ether
extract, crude fibre (AOAC 1995), acid
detergent fibre (ADF) and Neutral detergent
fibre (NDF) (Van Soest and Robertson 1985).
Statistical Analysis
Data collected were subjected to the analysis
of variance (ANOVA) for a completely
randomized design (SAS 1999). Differences
between the treatment means were tested using
the Duncan’s Multiple Range Test (SAS 1999)
Results
Composition of test ingredients and
experimental diets
The proximate and gross energy composition
of the test ingredients used in this study are
shown in Table 2. The proximate composition
of cassava by- products showed low levels of
crude protein for WCRM, CPM and CCM
ranging from 1.79% to 3.46%. The crude fibre
values were CPM (15.27%), CCM (18.75 %)
and CLM (16.38%). The energy value of
cassava products ranged from 11.70 to 14.51
MJ/kg. The crude protein value obtained for
earthworm meal (EWM) in this study was
67.41%, with an ash content of 5.24%. Table 3
shows the proximate composition of the
experimental diets. The values of crude protein
determined for experimental diets were
isonitrogeous ranging from 20.4% in the
control diet to 21.7% in Diet 8, while the crude
fibre range was 5.76% in the control to 7.06 %
in Diet 9. The ether extract range of
experimental diets was 3.57 % to 3.84 % while
the ash range in percentage was from 11.28%
in Diet 2 to 13.94% in Diet 8. The gross energy
content for the experimental diets was
isocaloric ranging from 13MJ/kg in Diet 2 to
13.12MJ/kg in Diet 8.
Table 2: Gross energy (MJ/kg), proximate (g/kg) and detergent fibre (g/kg) component of test
ingredients
Test Ingredient
WCRM CPM CCM CLM EWM
Gross Energy 11.80 11.70 11.80 14.51 10.53
Dry Matter 886.2 870.8 886.2 891.5 881.3
Crude Protein 26.5 34.6 17.9 153.4 674.1
Crude Fibre 17.9 152.7 187.5 163.8 21.4
Ether extract 8.6 15.8 9.3 59.7 5.63
Ash 23.7 31.8 30.6 142.9 52.4
Nitrogen Free Extract 809.5 635.9 640.9 371.7 77.1
Acid Detergent Fibre 465 342.5 229.5 326.8 38.2
Neutral Detergent Fibre 305.2 598.9 605.5 548.1 95.8
WCRM= Whole Cassava Root Meal ; CPM= Cassava Peel Meal ; CCM= Cassava Chaff Meal
CLM = Cassava Leaf Meal ; EWM= Earthworm Meal
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Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016 202
Table 3: Gross energy (MJ/kg), proximate (g/kg) and detergent fibre (g/kg) component of
experimental diets
Experimental Diets
1 2 3 4 5 6 7 8 9
Gross Energy
Dry matter
Crude Protein
Crude Fibre
Ether extract
Ash
Nitrogen Free
Extract
Acid Detergent Fibre
Neutral Detergent
Fibre
13.7
903.2
203.9
57.6
36.1
120.4
485.2
407.8
404.7
13.00
907.2
206.9
58.6
35.9
112.8
493
368
522.4
13.06
904.8
207.7
59.1
35.7
115.7
486.3
331.5
524.7
13.05
906.6
204.7
59.8
36.9
117.9
487.3
340.8
581.3
13.04
905.2
210.5
68.5
36.5
118.7
471
297.2
585.6
13.08
905.3
212.2
69.4
37.7
124.9
461.3
368
526.3
13.03
906.5
214.3
69.7
37.4
123.6
461.5
349.2
529.5
13.12
903.4
216.7
69.7
37.9
139.4
439.8
358
585.2
13.10
902.1
215.8
70.6
38.4
138.5
438.8
303.4
589.5
Table 4: Performance characteristics of rabbits fed experimental diets
Experimental Diets
1 2 3 4 5 6 7 8 9 SEM
Daily feed Intake (g) 73.02
Daily Weight gain (g) 11.25ab
Feed conversion ratio 6.71bc
73.02
11.25ab
6.71bc
72.37
8.93b
8.10ab
72.95
8.45b
8.63a
73.07
12.14a
6.11c
74.18
10.36ab
7.23abc
76.08
10.30ab
7.50abc
71.98
9.52ab
7.72abc
72.57
11.90a
6.15c
76.00
11.31ab
6.78abc
1.95
1.24
0.80
* a b c: Means within the same row bearing different superscripts are significant (P<0.05).
Live performance characteristics of rabbits fed experimental diets The average daily weight gain, feed intake and feed efficiency are presented in Table 4. Daily feed intake ranged between 72.37g in Diet 2 to 76.08g in Diet 6. Treatment effects on feed intake were not significantly (P>0.05) different. Dietary treatments however, significantly (P<0.05) influenced daily weight gain and feed conversion ratio with rabbits on diets 4 and 8 gaining significantly more weight than those on diets 3 and 2. Other dietary treatments had values comparable with Diets 4 and 8 for weight gain. Variation in weight gain between rabbits on the control diet and those of the other diets were not significant. The best feed conversion ratio was observed in rabbits on Diet 4 which also had the best weight gain. The poorest feed conversion ratio was in rabbits on Diet 3 and the value was significantly (P<0.05) lower than that of the
control and Diet 4. Rabbits on Diet 3 also had the lowest weight gain. Apart from Diet 3, the control diet had comparable (P>0.05) values with other dietary treatments for feed conversion ratio. Carcass yield, organs and wholesale cuts The carcass and organ characteristics of rabbits fed experimental diets are shown in Table 5. Apparent differences in the values for dressed weight, percentage dressed weight, shoulder, thigh, rack, liver and heart were not significant (P>0.05). However rabbits fed control diet had significantly (P<0.05) higher loin than those fed Diets 2 and 7. Also the control diet fed rabbits had significantly (P<0.05) higher head weight than those fed Diets 6 and 8. The skin weight of rabbits fed Diets 7 and 9 was significantly (P<0.05) higher, while those fed Diet 2 were significantly (P<0.05) lower than those fed the other diets.
Cassava products with earthworm meal supplementation for rabbit feeding; O.O. Kuforiji et al
203 Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016
Table 5: Effect of dietary treatment on edible parts in percentage dress weight and body organs,
product in percentage live weight
Treatment
1 2 3 4 5 6 7 8 9 SEM
Live
weight(g)
1706.6 1580.6 1624.1 166.06 1563.8 1754.2 1592 1802.8 1744.1 1.76
Dressed
weigh(g)t
868 797.3 827.3 869.3 780 888.1 795.7 904.3 923 1.64
Dressed
Percentage
50.86 50.44 50.94 52.18 49.88 50.66 49.98 50.16 52.92 1.05
Shoulder(g) 227.42 183.58 202.85 219.32 197.11 225.64 119.74 232.41 231.58 1.32
% Dress wt 26.20 23.02 24.52 25.47 25.23 25.39 24.48 25.70 25.09 1.36
Thigh(g) 317.69 312.94 308.33 309.56 284.78 328.55 300.62 360 343.17 1.96
% Dress wt 36.60 39.25 37.27 35.65 36.51 36.97 37.78 39.81 37.18 1.83
Loin(g) 219.95a 152.04c 189.45ab 197.59ab 177.45ab 198.00ab 174.82b 196.3ab 218.66ab 1.54
% Dress wt 25.34 19.07 22.90 22.73 22.75 22.28 21.97 21.71 23.69 1.27
Rack(g) 116.66 107.95 110.78 120.83 103.27 123.35 111.08 119.19 128.39 1.14
% Dress wt 13.44 13.54 13.39 13.90 13.24 13.99 13.96 13.18 13.91 0.96
Liver(g) 45.7 35.27 43.8 43.3 46.5 43.1 37.7 41.2 43.3 0.51
% Live wt 2.68 2.23 2.70 2.60 2.97 2.46 2.37 2.29 2.48 0.4
Heart(g) 4.0 3.2 3.8 4.77 3.8 5.02 4.13 4.97 5.11 0.09
% Live wt 0.23 0.20 0.23 0.29 0.24 0.286 0.26 0.28 0.29 0.05
Head(g) 154c 155.8bc 154.6bc 153.6cd 145.1cd 135.8d 153dc 201.1a 184.4ab 0.51
% Live wt 9.02 9.86 9.52 9.22 9.28 7.74 9.61 11.20 10.57 0.49
Skin(g) 151.4ab 136.3d 133.8b 135.6b 144.3b 141.1b 166.4a 142.7b 178.7a 0.85
% Live wt 8.87 8.62 8.24 8.14 9.23 8.04 10.45 7.92 10.25 0.81
Leg(g) 32.57bcd 29.7cd 34.3abc 31.1d 32.9abcd 33.6cd 35.8ab 41.7a 35.7abcd 0.14
% Live wt 1.91 1.88 2.11 1.87 2.10 1.90 2.25 2.31 2.05 0.12
* Means within the same row bearing different superscripts are significant (p<0.05)
Gut weight and dimension
The effect of dietary treatments on gut weight
(g) and gut dimension (cm) of the experimental
rabbits are shown in Table 6. There were
significant differences (P<0.05 ) for the weight
of the entire GIT with the rabbits on Diet 5
having the highest value of 285.3g (20.85% of
the live weight) while rabbits fed diet 6 had the
least weight of GIT 213.23g (12.12% live
weight). The full weight of small intestine was
also significantly (P<0.05) influenced by
dietary treatment with rabbits fed Diet 6 having
the highest value of 48.7g (3.01% live weight)
and rabbits fed Diet 3 having the lowest value
of 24.1 (1.11% live weight). The full weight of
caecum followed the same trend being
influenced significantly (P<0.05) by treatment
with rabbits fed Diet 5 having 102.3g (8.83%
live weight) while rabbitS fed Diet 6 have the
lowest value of 82.1 (5.08% live weight).
Similarly caecal length was significantly
(P<0.05) affected by dietary treatments. The
length of small intestines increased from Diet
1 until Diet 5, when the longest length of
198.2cm was recorded. Thereafter, the length
decreased until the shortest length was attained
in Diet 9.
Cassava products with earthworm meal supplementation for rabbit feeding; O.O. Kuforiji et al
Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016 204
Table 6: Effect of dietary treatment on organ weight (g) and gut dimension (cm) of experiment
rabbits
Dietary Treatment
1 2 3 4 5 6 7 8 9 SEM Weight of entire GIT
Full weight of small intestine
Empty wt of small intestine
Full weight of caecum
Empty weight of caecum
Length of small intestine
Length of caecum
228.01c
33.7b
20.96bc
90.20cd
41.46b
184.3ab
52.15ab
221.6c
31.2c
21.2ab
87.03cd
46.9b
183.7ab
48.4ab
250.27c
24.1a
20.5bc
105.7d
36.12cd
178.3e
47.7d
258.2c
33.1bcd
22.5ab
110.2b
45.3b
185.7bcd
47.2cd
285.3a
47.2a
24.27a
121.77a
40.2bcd
198.2a
47.0bc
213.23c
48.7d
16.2c
82.1bc
51.7a
141.1de
42.6d
219.36c
24.9cd
15.03d
88.2cd
23.6c
188bcd
49.3bc
220.7c
39.7cd
15.4d
88.74d
27.6c
151.3bcd
50.8ab
278.73ab
34.4bc
23.00ab
115b
43.7b
108.9bcd
54.06a
0.511
0.186
0.129
0.318
0.27
0.609
4.26
Cost-benefit analysis of experimental diets
Table 7 shows the cost of individual feed
ingredients. The result of the economic studies
of the feeding trials is presented in Table 8. The
percentage cost reduction on feed savings of
each diet, using the control diet as an index
progressively increases from diets 2 – 9 due to
minimal cost of the cassava based by-products.
The feed cost analysis suggested that the cost
of feed per unit of weight gain is reduced at
higher levels of cassava replacement with
either cassava peel or cassava chaff. The cost
of daily feed intake per weight gain was best
for animals on diet 9 (0.255) and highest for
those on diet 3 (0.411) as compared with the
control. The economic efficiency (feed
cost/weight gain) of weight gain reveals that
rabbits on diet 9 were significantly (P<0.05)
better than those on diets 1, 2. 3, 5, 6 and 7.
Table 7: Market Price of feed ingredients at
time of experiment
Ingredients cost (N/kg)
Whole cassava root
Cassava peel
Cassava chaff
Soya bean meal
Wheat offal
Fish meal
Born meal
Oyster shell
Vitamin/mineral permits
Salt
Vegetable oil
Earthworm
Cassava leaf
20
4
4
95
32
370
27
13
450
50
400
50
2
Milling at N50 per 30kg feed.
Table 8: Cost benefit analysis of feeding experimental diets to rabbits
Dietary Treatment
1 2 3 4 5 6 7 8 9 SEM
Cost/kg diet
% cost reduction relative to control diet
Average daily feed intake (g/d)
Cost of daily feed intake (N/d)
Average daily weight gain (g/d)
Economic efficiency of weight gain
feed cost (N) weight gain (g)
51.43
-
73.02
3.76
11.25ab
0.334bc
47.67
7.31c
72.37
3.45
8.93b
0.386bc
47.67
7.31c
72.95
3.48
8.45b
0.411c
45.79
10.97bc
73.07
3.35
12.14a
0.275ab
45.79
10.97bc
74.18
3.40
10.36ab
0.328bc
43.73
14.97ab
76.08
3.33
10.30ab
0.323bc
43.73
14.97ab
71.98
3.15
9.52ab
0.331bc
41.85
18.63a
72.54
3.04
11.90ab
0.281ab
41.85
18.63a
76.00
3.18
11.31ab
0.255a
0.95
2.54
1.95
0.65
1.24
0.78
*a,b, c = means within the same row bearing different superscripts are significant (p<0.05)
Cassava products with earthworm meal supplementation for rabbit feeding; O.O. Kuforiji et al
205 Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016
Discussion
The values obtained for the proximate analysis
of test ingredients of cassava by-products were
similar to those reported by Smith (1992) and
Kehinde et al. (2007). The utilization of
cassava and its products can be impaired by
high crude fibre (Agunbiade et al. 2007) which
were 15.27, 18.75 and16.38% for CPM, CCM
and CLM respectively. The highest bulk fibre
(NDF) was recorded for CCM (60.55%)
followed by CPM (59.89%) and 54.95% for
CLM, the least value of 30.52% was recorded
for WCRM. The percentage neutral detergent
fibre is directly related to crude fibre content of
feedstuffs but its utilization according to
Ranjhan (2001) is greatly affected by its acid
detergent fibre content which is related to fibre
digestibility. The lowest level of ADF of
22.95% recorded for CCM makes it potentially
more digestible than peel and leaf. The low
value of ADF for CCM could be attributed to
the different processing technique that the
feedstuff had undergone such as pressing,
soaking, fermentation and grinding which
according to Agunbiade et al. (2002) would
have led to reduction of its cyanide content
below the toxic level for livestock feed. The
crude protein value obtained for earthworm
meal (EWM) in this study was 67.41% which
makes it comparable with fish meal (FM) thus
making it a good source of protein and a
suitable substitute for FM. However this value
was higher than those reported by Mekada
(1979) and Orozco-Almanza et al. (1988) with
reported average value of 57.25%. The values
of crude protein determined for experimental
diets were isonitrogeous ranging from 20.4%
in the control diet to 21.7% in diet 8. These
values for crude protein diets fall within the
range of 18-22% recommended by Omole
(1982) for the efficient production of rabbits in
a tropical environment. The crude fibre range
for the experimental diets was 5.76% in the
control diet to 7.06% in diet 9, the values here
are lower than the recommended value of at
least 9% for normal growth of rabbits by
Champe and Maurice (1983).
The feed intake range of 71.80 -
76.08g/day was higher than 60.08 –
62.86g/day reported by Agunbiade et al.
(1999) in an experiment with cassava peel and
leaves in diet of rabbits but slightly lower than
the range of 71.00 – 80.10g/day reported by
Agunbiade et al. (2002) for performance
characteristics of weaner rabbits on cassava
peel balanced diets. The reason for this
difference in feed intake could be attributed to
the fact that CCM is better digested than CPM.
The values obtain for weight gain of rabbits in
this experiment were lower than those reported
by Agunbiade et al. (2002).
Replacing 75% WCRM by CPM in diets in
which between 0 and 50% of FM protein was
replaced by EWM protein did not bring about
significant difference in daily weight gain and
efficiency of feed conversion of rabbits for
diets 4 and 8 versus the control diet 1. The
results of this study indicate that up to 50% of
WCRM can be replaced by either CPM or
CCM, when 50% of FM protein is replaced by
EWM protein in cassava product based diets.
This result supports the findings of Agunbiade
et al. (2002) which suggest that cassava peels
can completely replace maize without
deleterious effects on growth and efficiency of
feed conversion in growing rabbits. The daily
weight gain of 8.45 – 12.14 is similar to 10.1g
reported by Adama and Nma (2002) when
groundnut leaves were fed to rabbits and 12.3g
reported by Omole and Ajayi (1976) who fed
dried brewer grains to rabbits. The general non significant effect of
dietary treatments on the majority of the carcass quality attributes observed in this study is an indication that the experimental diets were equally effective as the control diet in influencing carcass quality of rabbits. Similar observations on the influence of cassava-based diets in equally affecting carcass components of rabbits have been reported by Agunbiade et al. (1999). The dressing percentage in this trial was between 49.88% and 52.92%. This is in agreement with that reported for overall
Cassava products with earthworm meal supplementation for rabbit feeding; O.O. Kuforiji et al
Trop. Agric. (Trinidad) Vol. 93 No. 3 July 2016 206
dressing percentage of about 50% obtained by Osei and Doudu (1988). The percentage range of shoulder in this experiment is between 23.02 – 26.02%, higher than that reported by Rao et al. (1978) whose range was 17.10 – 18.70%. The difference observed might be due to differences in breed, sex or method of cutting. The percentage range for liver in the experimental rabbit which was 2.29 – 2.79 is lower than 3.18 -3.29 as reported by Essien and Udedibe (2007) for growing rabbit fed jack beans. The liver is one of the major organs involved in nutrient metabolism of the animal but since no significant difference (P>0.05) was observed between rabbits fed control diets and experimental diets, this shows that the different dietary treatments did not affect the experimental animals.
The significant effect of dietary treatments
on pelt % (skin) could be due to different levels
of sub-cutaneous fat deposition. Sobayo et al.
(2007) reported the value of 9.12 – 9.55%,
while in this trial 10.45% was recorded when
75% CCM replaced WCRM. This may
probably be due to the method of processing
CCM which could influence the fat available
to the animal when compared with the other
diets.
There was a significantly heavier weight of
the entire gastrointestinal tract (GIT) and full
weights of the small intestine and caecum
recorded for rabbits on diets 4, 5 and 9
compared with the control diet. This seems to
imply that ingesta stayed for a longer time in
the gut of these rabbits than those of other
experimental animals. Since fibre, particularly
hemicellulose component, is known to hasten
digester movement in the GIT, it would appear
that the lower ADF component in CPM and
CCM as WCRM is replaced, provided lower
fibre content, which could be responsible for
delayed transit time of digesta, as it moved
through the GIT.
Conclusion
There is a high level of competition between
man and livestock for grains like maize and
millets. Fish meal, a source of dietary protein
is also expensive. Animal production scientists
are therefore searching for cheaper but
available alternative feedstuffs. The findings
of this experiment showed that cassava peel
and cassava chaff can replace whole cassava
root meal as a main source of energy. Similarly
earthworm meal has been demonstrated to
have great potential as an inexpensive protein
substitute for fish meal in grower rabbit diets.
Further research should be conducted on the
possibility of the whole energy source of the
diet being supplied by cassava by-products
such as cassava peel and chaff with the entire
protein also supplied by earthworm meal
which are of no dietary importance to man.
Efforts should also be geared towards
encouraging vermiculture.
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