Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol81.Issue1-2.Sep1999:
Animal Feed Science and Technology
81 (1999) 43±56
Comparison of the nutritive value for laying hens of
diets containing azolla (Azolla pinnata) based on
formulation using digestible protein and digestible
amino acid versus total protein and total amino acid
A. Khatuna, M.A. Alib,*, J.G. Dingleb
a
Department of Animal Husbandry, Hajee Md. Danesh Agriculture college, Bashirhat, Dinajpur, Bangladesh
b
School of Veterinary Science and Animal Production, Gatton College, University of Queensland, Lawes,
Qld 4345, Australia
Received 18 November 1997; received in revised form 24 November 1998; accepted 22 May 1999
Abstract
Azolla (Azolla pinnata) was assessed for nutrient content and feeding value in laying hen diets.
Proximate analysis, together with the estimates of digestible protein, ADF, NDF and metabolizable
energy indicated that it was a fair source of plant protein (285.4 g kgÿ1) with a digestible protein
value of 219.8 g kgÿ1 and a metabolizable energy value of 7.59 MJ kgÿ1 (906 g kgÿ1 DM).
The feeding value of azolla in laying hens was studied in two feeding trials of 16 and 8 weeks
duration, respectively. Azolla meal was included at a level of 50 or 100 g kgÿ1 diet at the expense of
sesame meal in diets formulated on a total protein and total amino acid, or digestible protein and
digestible amino acid basis (Trial 1). In Trial 2, 150 and 200 g kgÿ1 azolla meal was included in
diets formulated using a total protein and total amino acid, or digestible protein and digestible
amino acid basis. L-lysine HCl and DL-methionine were added to the diets formulated using
digestible nutrients to adjust the digestible lysine and methionine contents to those in the wheat
sesame meal based control diet.
It was found that azolla meal could replace sesame meal on a digestible protein and digestible
amino acid basis up to 200 g kgÿ1 diet with egg production as the parameter, while it could replace
only up to 150 g kgÿ1 sesame meal in the diet based on total protein and total amino acids. Egg
mass output and feed conversion ratio were significantly better with up to 200 g kgÿ1 azolla meal in
the diet when included on a digestible protein and digestible amino acid basis but not when the diets
were formulated on a total protein and total amino acid basis. Feeding azolla on a digestible protein
*
Corresponding author. Tel.: +61-754-601-251; fax: +61-754-601-444
E-mail address: maa@warigal.uqg.uq.edu.au (M.A. Ali)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 7 1 - 1
44
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
and digestible amino acid basis maintained or improved protein efficiency. Feeding azolla on a total
or digestible nutrient basis had no affect on egg quality except egg size and yolk colour. Egg size
improved when the diets were formulated on a digestible protein and digestible amino acid basis.
Yolk colour was significantly improved with increasing levels of azolla meal and a longer period of
feeding. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Azolla; Composition; Layers; Feeding value; Digestible protein; Digestible amino acid
1. Introduction
Azolla (Azolla pinnata) is an aquatic fern found abundantly in ponds, ditches and
paddy fields in tropical and subtropical regions of the world. It contains 140±300 g kgÿ1
CP (Subudhi and Singh, 1978; Sreemannaryana et al., 1993) and can be used as a feed
ingredient for ruminants and non-ruminants (Subudhi and Singh, 1978; Tamang and
Samanta, 1993; Ali and Leeson, 1995). It is also a good source of pigments.
Nutritionists are now becoming interested in formulating diets on the basis of
digestible protein and digestible amino acids (Vogt, 1988; Rhone Poulenc Animal
Nutrition, 1989; Fernandez et al., 1995). The amino acid availability of feed ingredients
varies depending upon processing, fibre content, protease inhibitors and the presence of
complexes (Carpenter and Booth, 1973; Raharjo and Farrell, 1984; Han et al., 1991;
Parsons et al., 1992). The performance of laying hens improved when the feed
formulation was based on digestible lysine and digestible methionine concentration rather
than total lysine and total methionine concentration (Bougon and Joly, 1990). Rostagno
et al. (1995) demonstrated that there was considerable benefit in feeding cheap byproducts to broilers when diets were balanced with respect to digestible amino acids. It
has been demonstrated that the digestible lysine or methionine measured in roosters
reasonably reflects the availability of the respective amino acid in a chick growth assay
(Han et al., 1991; Parsons et al., 1992). Ali and Leeson (1995) found lower digestible
protein and amino acids in azolla meal than in rice polish and snail meal. Reports on the
feeding value of azolla in the diet of laying hens are scanty. Variation in composition and
lack of information of azolla meal makes incorporation in the diet of laying hens more
difficult.
The present study was therefore undertaken to determine the chemical composition,
metabolizable energy and digestible protein contents and subsequently the feeding value
of azolla meal on a total protein and total amino acid basis, compared with a digestible
protein and digestible amino acid basis for laying hens.
2. Materials and methods
2.1. Feed source
Fresh azolla was harvested from local ponds and then sun-dried. It was ground (4 mm
screen) and stored in air-tight plastic bags until used.
45
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 1
Composition of experimental diets for determination of protein digestibility in layers
Ingredients
Starch
Azolla
Sawdust
Bone meal
Salt
Vitamin mineral premixa
Purified diets (g kgÿ1)
A
B
757.5
200
10
25
5
2.5
897.5
±
60
35
5
2.5
a
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
2.2. Metabolizable energy
The apparent metabolizable energy value of azolla was calculated by the chemical
method of Sibbald et al. (1963).
2.3. Protein digestibility
Protein digestibility of azolla meal was measured by including the ingredient at
200 g kgÿ1 as the sole source of protein in a purified diet, together with a control diet
which was essentially nitrogen-free (McNab and Shannon, 1972) except that some
sawdust was incorporated instead of alphafloc (cellulose). The composition of the diets is
shown in Table 1. Chromic oxide was added at a level of 5 g kgÿ1 diet as an indigestible
marker.
Each diet was fed ad libitum to ten 12-week-old Rhode Island Red cockerels. The birds
were given an adjustment period of 5 days on the diet. On day 6, birds were killed by
cervical dislocation. Immediately after death, the abdomen was opened and the ileum
removed. Digesta were collected from the fifth segment of the ileum, about 10 cm
anterior to the ileo-caecal junction to avoid potential contamination with urine. Protein
digestibility was calculated by the method of Lodhi et al. (1970) with endogenous N
correction determined from chickens fed the nitrogen-free diet.
2.4. Diet formulations
Diets were formulated on a total protein and total amino acids versus digestible protein
and digestible amino acids basis. Nutrients in the diets were adjusted close to the
requirements of brown egg layers (NRC, 1994) while the digestible protein and digestible
lysine contents were similar to Vogt (1988). Digestible protein content was calculated
from the analysed crude protein values of the ingredients and from their digestibility
coefficients of protein/nitrogen except for azolla which was the determined value. The
digestible amino acid contents of the ingredients were calculated from the digestibility
46
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
coefficients of amino acid and total amino acid values of the ingredients (NRC, 1994)
except for processed full-fat-soybean (Scragg, 1994) and azolla meal (Ali and Leeson,
1995) with adjustment for the increased protein content of our azolla meal. The
digestibility coefficients of nitrogen and amino acids used were those found for wheat and
processed full-fat-soybean (Scragg, 1994) sesame meal (NRC, 1994) rice polishings and
azolla meal (Ali and Leeson, 1995) with adjustment of the amino acid digestibility
coefficients for the increased nitrogen digestibility of azolla meal.
2.5. Layer trials
The feeding value of azolla meal was determined in two feeding trials using 579
Shaver Starcross commercial layers. In Trial 1, diets were prepared by including azolla
meal at a level of 50 and 100 g kgÿ1 formulated on a total protein and total amino acid
basis, and on a digestible protein and digestible amino acid basis by replacing some
sesame meal and full-fat-soybean to adjust the digestible protein, and digestible lysine
and methionine (Table 2).
In Trial 2, diets were prepared with 150 and 200 g kgÿ1 azolla meal on the same basis
as in Trial 1. Synthetic L-lysine HCl and DL-methionine were added to the diets
formulated on a digestible nutrient basis to adjust the digestible lysine and methionine
contents (Table 3).
In Trial 1, 60 laying pullets 43-week-old and in Trial 2, 80 laying pullets 28-week-old
were used. In Trial 1, each diet was applied to three replications of four birds, while in
Trial 2, each diet was applied to four replications of four birds. The birds were reared in
individual cages in an open house. All mash dry feed was supplied ad libitum throughout
the experimental period. 16 h light was maintained during the experimental periods. Prior
to the experiment all birds were adjusted in cages for 2 weeks with a common layer diet.
The experiments continued for 16 and 8 weeks for Trials 1 and 2, respectively.
During the experiments, daily egg production, egg weight and weekly feed
consumption were recorded. In Trial 1, one egg from each replicate was collected for
the first 3 days and last 3 days of weeks 4, 8, 12 and 16 and in Trial 2, one egg from each
replicate was collected on the last 3 days of weeks 4 and 8 to determine egg quality. The
eggs were weighed after collection. The external egg quality characteristics measured
were shape index (Reddy et al., 1979) egg shell breaking strength (Ar et al., 1979) shell
surface area (Carter, 1975) per cent shell and shell thickness. The internal egg quality
characteristics measured were Haugh Unit (Haugh, 1937) albumen index (Heiman and
Carver, 1936) albumen dry matter, yolk colour score (Roche Yolk Colour fan) yolk index
(Wesley and Stadelman, 1959) and yolk dry matter. Hen-day egg production, egg mass
output and feed conversion ratio (feed consumed per unit of egg mass produced) were
determined from the recorded data. Protein efficiency ratio was calculated as per Nagra
and Virk (1986) using the value of 0.12 g protein in 1 g whole egg (Lodhi et al., 1980).
2.6. Chemical analysis
Azolla meal was analysed for proximate composition using standard procedures
(AOAC, 1990). Acid detergent fibre (ADF) and neutral detergent fibre (NDF) were
47
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 2
Composition of layer diets containing graded levels of azolla meal (Trial 1)
Ingredients
Wheat
Rice polish
Sesame meal
Full-fat soybean (processed)
Azolla meal
Oyster shell
Bone meal
Salt
Vitamin mineral premixc
Nutrient composition (fresh basis)
Crude protein (g kgÿ1)
Digestible protein (g kgÿ1)
Total lysine (g kgÿ1)
Digestible lysine (g kgÿ1)
Total methionine (g kgÿ1)
Digestible methionine (g kgÿ1)
ME (MJ kg±1)
Crude fibre (g kgÿ1)
Calcium (g kgÿ1)
Av. phosphorus (g kgÿ1)
Level of azolla meal (g kgÿ1)
0 (Control)
50 (TPTAa)
50 (DPDAb)
100 (TPTA)
100 (DPDA)
490
190
115
120
±
65
15
5
+
490
190
95
90
50
65
15
5
+
470
180
110
105
50
65
15
5
+
480
180
65
90
100
65
15
5
+
470
180
70
95
100
65
15
5
+
178.7
156.3
7.87
6.72
3.80
3.42
11.57
47.6
32.1
3.5
174.0
150.2
7.05
5.95
3.48
3.09
11.35
50.6
32.2
3.4
180.9
156.6
7.55
6.36
3.73
3.32
11.33
50.9
32.5
3.5
176.0
150.3
6.88
5.69
3.15
2.74
11.20
53.7
32.3
3.4
178.5
152.6
7.24
5.95
3.44
3.04
11.20
54.7
32.8
3.5
a
TPTA = Total protein and total amino acids.
DPDA = Digestible protein and digestible amino acids.
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12 mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
b
c
determined by the methods of Goering and Van Soest (1970). The starch content of azolla
was determined by the method of Lane and Eynon (1923). Free sugar was estimated by a
colorimetric method (Dubois et al., 1951). Chromic oxide content in feed and excreta was
measured using the method described by Hill and Anderson (1958).
2.7. Statistical analysis
Data were subjected to analysis of variance (Steel and Torrie, 1980) and significant
differences between treatments were identified by least significant difference.
3. Results and discussion
3.1. Chemical composition
Air dried azolla meal was analysed for its nutrient content. It contained dry matter
(905.89 g kgÿ1) which was similar to Ali and Leeson (1995) and Tamang and Samanta
48
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 3
Composition of layer diets containing graded levels of azolla meal (Trial 2)
Ingredients
Wheat
Rice polish
Sesame meal
Full-fat Soybean (Processed)
Azolla meal
Oyster shell
Bone meal
Salt
Soybean oil
L-lysine HCl
DL-methionine
Vitamin mineral premixc
Nutrient Composition (fresh basis)
Crude protein (g kgÿ1)
Digestible protein (g kgÿ1)
Total lysine (g kgÿ1)
Digestible lysine (g kgÿ1)
Total methionine (g kgÿ1)
Digestible methionine (g kgÿ1)
ME (MJ kg±1)
Crude fibre (g kgÿ1)
Calcium (g kgÿ1)
Av. phosphorus (g kgÿ1)
Level of azolla meal (g kgÿ1)
0 (Control)
150 (TPTAa) 150 (DPDAb)
200 (TPTA) 200 (DPDA)
490
190
115
120
±
65
15
5
±
±
±
+
447
160
60
75
150
65
15
5
23
±
±
+
432.45
140
75
90
150
65
15
5
26
0.95
0.60
+
428
145
50
60
200
65
15
5
32
±
±
+
404.9
140
55
80
200
65
15
5
33
1.3
0.8
+
178.7
156.3
7.87
6.72
3.80
3.42
11.57
47.6
32.1
3.5
175.0
148.0
6.41
5.24
3.11
2.67
11.57
56.3
32.8
3.5
182.2
155.3
7.67
6.70
3.89
3.44
11.57
55.8
33.1
3.5
175.0
146.5
6.35
5.14
3.03
2.56
11.57
59.1
33.2
3.5
183.0
154.0
8.00
6.72
3.82
3.42
11.57
59.6
33.4
3.5
a
TPTA = Total protein and total amino acids.
DPDA = Digestible protein and digestible amino acids.
c
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12 mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
b
(1993). Crude protein (285.4 g kgÿ1) was similar to sesame meal (Rahman, 1992) and
grain legumes (Rahman, 1981). The analysed crude protein content of azolla was similar
to the values reported by Buckingham et al. (1978) and Singh et al. (1983) but higher than
the values reported by others (Tamang and Samanta, 1993; Ali and Leeson, 1995).
Digestible protein (219.8 g kgÿ1) was higher than the values of Tamany et al., (1992) and
Ali and Leeson (1995). Crude fibre (123.8 g kgÿ1) was similar to the values reported by
Sreemannaryana et al. (1993) and Ali and Leeson (1995) but slightly higher than the
values of Subudhi and Singh (1978) and lower than the values of Querubin et al. (1986)
and Tamang and Samanta (1993). ADF (334.1 g kgÿ1) was similar to the values reported
by Buckingham et al. (1978) but lower than those of Tamang and Samanta (1993) and Ali
and Leeson (1995). NDF (445.7 g kgÿ1) was lower than the reported value of others
(Querubin et al., 1986;Tamang and Samanta, 1993; Ali and Leeson, 1995). Ash
(169.2 g kgÿ1)was lower than most reports (Singh et al., 1983; Querubin et al., 1986;
Tamang and Samanta, 1993; Ali and Leeson, 1995) but similar to that of Buckingham
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
49
et al. (1978). The metabolizable energy (7.59 MJ kgÿ1) was comparable to that of duck
weed (Akter, 1995) but higher than reported previously for azolla meal (Ali and Leeson,
1995). These differences indicate that the azolla meal used in these trials was of a higher
quality.
3.2. Egg production
The performance of laying hens in Trial 1 and 2 is shown in Tables 4 and 5
respectively. Feeding azolla meal on a digestible protein and digestible amino acid basis
produced better egg production than with the control diet or diets formulated on a total
protein and total amino acid basis. Hen-day egg production with 50 g kgÿ1 azolla meal
using digestible protein and digestible amino acid was improved by 6.4 and 9.9% over the
control diet and the diet with 50 g kgÿ1 azolla meal on total protein and total amino acids
(Trial 1) while with 100 g kgÿ1 azolla meal on digestible protein and digestible amino
acid egg production improved by 2.0 and 5.7% over the control diet and 100 g kgÿ1
azolla meal on total protein and total amino acid. However, those effects were not
significant at p < 0.05. In Trial 2, hen-day egg production of birds fed 200 g kgÿ1 azolla
meal on total protein and total amino acid was significantly lower than that of hens fed
the control diet or 150 or 200 g kgÿ1 azolla meal on digestible protein and digestible
amino acid basis. These results indicate that azolla meal can be used up to 150 g kgÿ1 on
a total protein and total amino acid basis for laying hen but egg production was reduced at
200 g kgÿ1 level. The results are consistent with those of Bastian (1987) but disagree with
those of Singh and Subudhi (1978). However, when azolla meal was fed at 150 and
200 g kgÿ1 on a digestible protein and digestible amino acid basis egg production
significantly improved by 5.5 and 4.3% over that obtained when azolla meal was fed at
150 and 200 g kgÿ1 on a total protein and total amino acid basis. Better egg production in
diets formulated on digestible protein and digestible amino acid basis might be due to
better precision of diet formulation. These results suggest that azolla meal can replace
sesame meal on a digestible protein and digestible amino acid basis at up to 200 g kgÿ1
diet of laying hens but only to 150 g kgÿ1 diet when the diet is formulated on a total
protein and total amino acid basis.
3.3. Egg mass output
The egg mass output (g egg/day) of hens fed diets with 50 and 100 g kgÿ1 azolla meal
on a digestible protein and digestible amino acid basis improved over the control diet and
diets formulated with a similar level of azolla meal on a total protein and total amino acid
basis (Trial 1). However, the differences were not significant (p > 0.05). At 150 and
200 g kgÿ1 azolla meal fed on a digestible protein and digestible amino acid basis the egg
mass output significantly improved over the control diet and 150 and 200 g kgÿ1 azolla
meal on a total protein and total amino acid basis (Trial 2). The results confirm earlier
observations of improved egg mass output in laying hens when fed diets formulated on
the basis of digestible protein and digestible amino acids (Bougon and Joly, 1990; Joly,
1994).
50
Performance (Mean SE)
Hen-day egg production (%)
Egg mass output (g egg/bird/day)
Feed consumption (g/bird/day)
Feed efficiency
PER
Livability (%)
a
*
Level of azolla meal (g kgÿ1)
0 (Control)
50 (TPTA)
50 (DPDA)
100 (TPTA)
100 (DPDA)
75.7 3.5
49.5 2.5
118.5 2.8
2.42 0.66
28.1 0.3 b
100.0
72.2 0.8
48.3 1.4
118.6 3.6
2.47 0.01
26.4 0.1 c
100.0
82.1 2.2
52.7 1.5
119.4 1.4
2.28 0.04
29.5 0.4 a
100.0
72.0 5.3
47.3 2.6
118.2 2.0
2.52 0.13
26.3 0.3 c
100.0
77.7 1.0
50.9 0.4
119.2 0.4
2.36 0.16
27.9 0.2 b
100.0
Means in the rows bearing similar letters do not differ significantly.
p < 0.05.
CV
(%)
Lsd values and level
of significance
6.3
5.4
3.5
4.13
1.7
NS
NS
NS
NS
1.3*
NS
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 4
Performance of laying hens fed a diet containing 50 or 100 g kgÿ1 azolla meal on the basis of total protein and total amino acids, or digestible protein and digestible
amino acids (Trial 1)a
Performance (Mean SE)
Hen-day production (%)
Egg mass output (g egg/day)
Feed consumption (g/bird/day)
Feed efficiency
PER
Livability (%)
a
*
Level of azolla meal (g kg±1)
0 (Control)
150 (TPTA)
150 (DPDA)
200 (TPTA)
200 (DPDA)
73.5 1.3 ab
39.6 0.7 c
107.3 2.2 c
2.75 0.09 b
25.1 0.9 bc
100.0
70.8 1.3 bc
38.2 1.1 c
112.6 1.5 ab
2.99 0.07 a
23.2 0.6 c
100.0
76.3 0.4 a
44.5 0.2 a
108.2 1.2 bc
2.43 0.03 c
27.5 0.3 a
100.0
69.4 1.1 c
38.9 0.5 c
113.6 0.6 a
2.95 0.03 a
22.9 0.3 c
100.0
73.7 0.9 ab
42.1 0.5 b
107.3 1.3 c
2.56 0.03 c
26.1 0.3 ab
100.0
Means in the rows bearing similar letters do not differ significantly.
p < 0.05. ** p < 0.01.
CV (%)
Lsd values and level
of significance
2.7
3.0
2.9
4.07
4.2
3.0*
1.9*
4.9**
0.16*
2.3*
NS
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 5
Performance of laying hens fed a diet containing 150 or 200 g kgÿ1 azolla meal formulated on the basis of total protein and total amino acids, or digestible protein and
digestible amino acids (Trial 2)a
51
52
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
3.4. Feed consumption
Feed consumption was similar in all dietary treatments in Trial 1 but it significantly
increased for hens fed diets with 150 and 200 g kgÿ1 azolla meal on a total protein and
total amino acids basis compared with hens fed the control diet in Trial 2. Feed
consumption of birds fed diets containing 150 and 200 g kgÿ1 azolla meal on a digestible
protein and digestible amino acid basis was similar to that of birds fed the control diet.
The results partially agree with Querubin et al. (1986) who observed increased feed
consumption of birds fed diets containing up to 150 g kgÿ1 azolla meal on a total protein
and total amino acid basis but they disagree with those of Bastian (1987).
3.5. Feed efficiency
It is evident from Tables 4 and 5 that better feed efficiencies were found when azolla
meal was fed at 50 and 100 g kgÿ1 (Trial 1) but significantly improved over the control
when fed at 150 and 200 g kgÿ1 when formulated on a digestible protein and digestible
amino acid basis (Trial 2) but it was poorer when the diets were formulated on a total
protein and total amino acid basis. Improved feed efficiency in diets formulated on a
digestible nutrient basis is mainly due to better egg production. The results are similar to
earlier observations (Bougon and Joly, 1990; Johnson, 1992; Joly, 1994) of higher feed
efficiency when fed on a digestible nutrient basis and confirm the reduced feed efficiency
found in a broiler study (Querubin et al., 1986) when they were formulated on a total
protein and total amino acids basis.
3.6. Protein efficiency ratio
Protein efficiency ratio (PER) improved (p < 0.05) for the 50 and 150 g kgÿ1 azolla
meal diet formulated on the basis of digestible protein and digestible amino acid
compared with the PER of the control diet or the diets with a similar level of azolla meal
and formulated on the basis of total protein and total amino acid (Tables 4 and 5). PER for
100 and 200 g azolla meal on a digestible protein and digestible amino acid basis
improved (p < 0.05) when compared to similar levels of azolla meal on a total protein and
total amino acid basis but was similar to the control diet. Feeding azolla meal on a
digestible protein and digestible amino acid basis maintained or improved protein
efficiency but it was significantly reduced when fed on total protein and total amino acid
basis.
3.7. Livability
No bird died in any treatment during the experiments indicating that azolla meal had no
deleterious effect on livability. The results were consistent with Singh and Subudhi
(1978) and Castillo et al. (1981) who found no effect on the livability of chicks and
broilers.
Egg quality
Egg weight (g)
Yolk
Colour
Score
a
*
Experiment
No.
28-dayPeriod/week
Levels of azolla meal (g kgÿ1)
0 (Control)
50/150
(TPTA)
50/150
(DPDA)
100/200
(TPTA)
100/200
(DPDA)
CV
(%)
Lsd
values and level
of significance
1
1
1
1
1
1st
2nd
3rd
4th
Mean
62.1 0.5
65.0 0.7
67.0 0.7
67.0 1.0
65.3 0.7
63.3 0.8
66.9 0.7
68.7 1.2
68.9 1.5
67.0 1.2
61.9 1.5
63.9 1.0
65.9 1.2
65.4 1.2
64.3 1.1
62.6 2.1
65.6 2.9
67.4 3.1
67.4 3.3
65.8 2.8
63.1 0.7
65.2 0.8
67.4 0.8
66.1 0.4
65.5 0.6
0.5
4.5
4.4
4.9
4.2
NS
NS
NS
NS
NS
2
2
2
1st
2nd
Mean
54.5 0.6 b
56.6 0.7 b
55.6 0.6 b
53.6 0.8 b
53.4 0.4 c
54.3 0.6 c
56.4 0.6 a
58.8 0.5 a
57.6 0.4 a
54.3 0.5 b
55.7 0.6 b
55.0 0.6 b
56.3 0.2 a
57.6 0.7 ab
57.0 0.4 ab
2.2
2.2
2.0
1.8**
1.9**
1.3**
1
1
1
1
1
Starting
4th week
8th week
12th week
16th week
1.3 0.2
0.7 0.1
1.0 0.0
1.0 0.0
1.3 0.3
2.0 0.1
2.4 0.3
3.0 0.3
3.3 0.1
3.8 0.3
1.8 0.2
2.4 0.5
2.7 0.3
3.3 0.1
3.5 0.5
2.3 0.1
3.4 0.3
4.0 0.2
4.6 0.2
5.4 0.3
a
a
a
a
a
24.4
27.3
13.9
10.1
14.0
0.6*
0.9*
0.6*
0.5*
0.9*
2
2
4th week
8th week
1.3 0.1 c
1.3 0.1 c
9.1 0.3 a
9.6 0.4 a
7.2
10.5
1.5*
1.1*
c
c
d
c
c
Values in the rows bearing similar letters do not differ significantly.
p < 0.05. ** p < 0.01.
b
b
c
b
b
7.0 0.5 b
8.1 0.2 b
b
b
c
b
b
6.8 0.3 b
8.1 0.3 b
ab
a
b
a
a
8.9 0.2 a
8.9 0.1 ab
2.7 0.1
3.7 0.2
4.9 0.1
5.0 0.1
5.2 0.2
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 6
Egg quality characteristics of laying hens fed diets containing azolla meal formulated on the basis of total protein and total amino acids, or on digestible protein and
digestible amino acids basis (Trials 1 and 2)a
53
54
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
3.8. Egg quality
The external and internal characteristics of eggs in feeding Trials 1 and 2 are presented
in Table 6. It is evident that, apart from egg weight and yolk colour, egg quality
characteristics were not affected by the dietary treatments. Feeding azolla meal on a
digestible protein and digestible amino acid basis improved egg weight (Trial 2). The
improved egg size for diets formulated on a digestible nutrient basis might be due to
better critical amino acid balance (Morris and Gous, 1988). The results were similar to
the earlier observations of Bougon and Joly (1990) and Joly (1994). The yolk colour
significantly improved with increasing levels of azolla meal and period of feeding
whether fed on a total or on a digestible protein and amino acid basis. These results were
similar to the observations of Singh and Subudhi (1978) and Bastian (1987).
The results of our study indicated that azolla meal was a fair source of plant protein
and metabolizable energy for laying hens. When azolla meal replaced sesame meal (wt./
wt.) on a digestible protein and digestible amino acid basis performance was improved
over that obtained when the replacement was on the basis of total protein and amino
acids.
Acknowledgements
We gratefully acknowledge the provision of facilities by the Department of Poultry
Science, Bangladesh Agricultural University, Mynensingh, Bangladesh. The help of Mr.
S. C. Das during the experiments is greatly appreciated.
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81 (1999) 43±56
Comparison of the nutritive value for laying hens of
diets containing azolla (Azolla pinnata) based on
formulation using digestible protein and digestible
amino acid versus total protein and total amino acid
A. Khatuna, M.A. Alib,*, J.G. Dingleb
a
Department of Animal Husbandry, Hajee Md. Danesh Agriculture college, Bashirhat, Dinajpur, Bangladesh
b
School of Veterinary Science and Animal Production, Gatton College, University of Queensland, Lawes,
Qld 4345, Australia
Received 18 November 1997; received in revised form 24 November 1998; accepted 22 May 1999
Abstract
Azolla (Azolla pinnata) was assessed for nutrient content and feeding value in laying hen diets.
Proximate analysis, together with the estimates of digestible protein, ADF, NDF and metabolizable
energy indicated that it was a fair source of plant protein (285.4 g kgÿ1) with a digestible protein
value of 219.8 g kgÿ1 and a metabolizable energy value of 7.59 MJ kgÿ1 (906 g kgÿ1 DM).
The feeding value of azolla in laying hens was studied in two feeding trials of 16 and 8 weeks
duration, respectively. Azolla meal was included at a level of 50 or 100 g kgÿ1 diet at the expense of
sesame meal in diets formulated on a total protein and total amino acid, or digestible protein and
digestible amino acid basis (Trial 1). In Trial 2, 150 and 200 g kgÿ1 azolla meal was included in
diets formulated using a total protein and total amino acid, or digestible protein and digestible
amino acid basis. L-lysine HCl and DL-methionine were added to the diets formulated using
digestible nutrients to adjust the digestible lysine and methionine contents to those in the wheat
sesame meal based control diet.
It was found that azolla meal could replace sesame meal on a digestible protein and digestible
amino acid basis up to 200 g kgÿ1 diet with egg production as the parameter, while it could replace
only up to 150 g kgÿ1 sesame meal in the diet based on total protein and total amino acids. Egg
mass output and feed conversion ratio were significantly better with up to 200 g kgÿ1 azolla meal in
the diet when included on a digestible protein and digestible amino acid basis but not when the diets
were formulated on a total protein and total amino acid basis. Feeding azolla on a digestible protein
*
Corresponding author. Tel.: +61-754-601-251; fax: +61-754-601-444
E-mail address: maa@warigal.uqg.uq.edu.au (M.A. Ali)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 7 1 - 1
44
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
and digestible amino acid basis maintained or improved protein efficiency. Feeding azolla on a total
or digestible nutrient basis had no affect on egg quality except egg size and yolk colour. Egg size
improved when the diets were formulated on a digestible protein and digestible amino acid basis.
Yolk colour was significantly improved with increasing levels of azolla meal and a longer period of
feeding. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Azolla; Composition; Layers; Feeding value; Digestible protein; Digestible amino acid
1. Introduction
Azolla (Azolla pinnata) is an aquatic fern found abundantly in ponds, ditches and
paddy fields in tropical and subtropical regions of the world. It contains 140±300 g kgÿ1
CP (Subudhi and Singh, 1978; Sreemannaryana et al., 1993) and can be used as a feed
ingredient for ruminants and non-ruminants (Subudhi and Singh, 1978; Tamang and
Samanta, 1993; Ali and Leeson, 1995). It is also a good source of pigments.
Nutritionists are now becoming interested in formulating diets on the basis of
digestible protein and digestible amino acids (Vogt, 1988; Rhone Poulenc Animal
Nutrition, 1989; Fernandez et al., 1995). The amino acid availability of feed ingredients
varies depending upon processing, fibre content, protease inhibitors and the presence of
complexes (Carpenter and Booth, 1973; Raharjo and Farrell, 1984; Han et al., 1991;
Parsons et al., 1992). The performance of laying hens improved when the feed
formulation was based on digestible lysine and digestible methionine concentration rather
than total lysine and total methionine concentration (Bougon and Joly, 1990). Rostagno
et al. (1995) demonstrated that there was considerable benefit in feeding cheap byproducts to broilers when diets were balanced with respect to digestible amino acids. It
has been demonstrated that the digestible lysine or methionine measured in roosters
reasonably reflects the availability of the respective amino acid in a chick growth assay
(Han et al., 1991; Parsons et al., 1992). Ali and Leeson (1995) found lower digestible
protein and amino acids in azolla meal than in rice polish and snail meal. Reports on the
feeding value of azolla in the diet of laying hens are scanty. Variation in composition and
lack of information of azolla meal makes incorporation in the diet of laying hens more
difficult.
The present study was therefore undertaken to determine the chemical composition,
metabolizable energy and digestible protein contents and subsequently the feeding value
of azolla meal on a total protein and total amino acid basis, compared with a digestible
protein and digestible amino acid basis for laying hens.
2. Materials and methods
2.1. Feed source
Fresh azolla was harvested from local ponds and then sun-dried. It was ground (4 mm
screen) and stored in air-tight plastic bags until used.
45
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 1
Composition of experimental diets for determination of protein digestibility in layers
Ingredients
Starch
Azolla
Sawdust
Bone meal
Salt
Vitamin mineral premixa
Purified diets (g kgÿ1)
A
B
757.5
200
10
25
5
2.5
897.5
±
60
35
5
2.5
a
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
2.2. Metabolizable energy
The apparent metabolizable energy value of azolla was calculated by the chemical
method of Sibbald et al. (1963).
2.3. Protein digestibility
Protein digestibility of azolla meal was measured by including the ingredient at
200 g kgÿ1 as the sole source of protein in a purified diet, together with a control diet
which was essentially nitrogen-free (McNab and Shannon, 1972) except that some
sawdust was incorporated instead of alphafloc (cellulose). The composition of the diets is
shown in Table 1. Chromic oxide was added at a level of 5 g kgÿ1 diet as an indigestible
marker.
Each diet was fed ad libitum to ten 12-week-old Rhode Island Red cockerels. The birds
were given an adjustment period of 5 days on the diet. On day 6, birds were killed by
cervical dislocation. Immediately after death, the abdomen was opened and the ileum
removed. Digesta were collected from the fifth segment of the ileum, about 10 cm
anterior to the ileo-caecal junction to avoid potential contamination with urine. Protein
digestibility was calculated by the method of Lodhi et al. (1970) with endogenous N
correction determined from chickens fed the nitrogen-free diet.
2.4. Diet formulations
Diets were formulated on a total protein and total amino acids versus digestible protein
and digestible amino acids basis. Nutrients in the diets were adjusted close to the
requirements of brown egg layers (NRC, 1994) while the digestible protein and digestible
lysine contents were similar to Vogt (1988). Digestible protein content was calculated
from the analysed crude protein values of the ingredients and from their digestibility
coefficients of protein/nitrogen except for azolla which was the determined value. The
digestible amino acid contents of the ingredients were calculated from the digestibility
46
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
coefficients of amino acid and total amino acid values of the ingredients (NRC, 1994)
except for processed full-fat-soybean (Scragg, 1994) and azolla meal (Ali and Leeson,
1995) with adjustment for the increased protein content of our azolla meal. The
digestibility coefficients of nitrogen and amino acids used were those found for wheat and
processed full-fat-soybean (Scragg, 1994) sesame meal (NRC, 1994) rice polishings and
azolla meal (Ali and Leeson, 1995) with adjustment of the amino acid digestibility
coefficients for the increased nitrogen digestibility of azolla meal.
2.5. Layer trials
The feeding value of azolla meal was determined in two feeding trials using 579
Shaver Starcross commercial layers. In Trial 1, diets were prepared by including azolla
meal at a level of 50 and 100 g kgÿ1 formulated on a total protein and total amino acid
basis, and on a digestible protein and digestible amino acid basis by replacing some
sesame meal and full-fat-soybean to adjust the digestible protein, and digestible lysine
and methionine (Table 2).
In Trial 2, diets were prepared with 150 and 200 g kgÿ1 azolla meal on the same basis
as in Trial 1. Synthetic L-lysine HCl and DL-methionine were added to the diets
formulated on a digestible nutrient basis to adjust the digestible lysine and methionine
contents (Table 3).
In Trial 1, 60 laying pullets 43-week-old and in Trial 2, 80 laying pullets 28-week-old
were used. In Trial 1, each diet was applied to three replications of four birds, while in
Trial 2, each diet was applied to four replications of four birds. The birds were reared in
individual cages in an open house. All mash dry feed was supplied ad libitum throughout
the experimental period. 16 h light was maintained during the experimental periods. Prior
to the experiment all birds were adjusted in cages for 2 weeks with a common layer diet.
The experiments continued for 16 and 8 weeks for Trials 1 and 2, respectively.
During the experiments, daily egg production, egg weight and weekly feed
consumption were recorded. In Trial 1, one egg from each replicate was collected for
the first 3 days and last 3 days of weeks 4, 8, 12 and 16 and in Trial 2, one egg from each
replicate was collected on the last 3 days of weeks 4 and 8 to determine egg quality. The
eggs were weighed after collection. The external egg quality characteristics measured
were shape index (Reddy et al., 1979) egg shell breaking strength (Ar et al., 1979) shell
surface area (Carter, 1975) per cent shell and shell thickness. The internal egg quality
characteristics measured were Haugh Unit (Haugh, 1937) albumen index (Heiman and
Carver, 1936) albumen dry matter, yolk colour score (Roche Yolk Colour fan) yolk index
(Wesley and Stadelman, 1959) and yolk dry matter. Hen-day egg production, egg mass
output and feed conversion ratio (feed consumed per unit of egg mass produced) were
determined from the recorded data. Protein efficiency ratio was calculated as per Nagra
and Virk (1986) using the value of 0.12 g protein in 1 g whole egg (Lodhi et al., 1980).
2.6. Chemical analysis
Azolla meal was analysed for proximate composition using standard procedures
(AOAC, 1990). Acid detergent fibre (ADF) and neutral detergent fibre (NDF) were
47
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 2
Composition of layer diets containing graded levels of azolla meal (Trial 1)
Ingredients
Wheat
Rice polish
Sesame meal
Full-fat soybean (processed)
Azolla meal
Oyster shell
Bone meal
Salt
Vitamin mineral premixc
Nutrient composition (fresh basis)
Crude protein (g kgÿ1)
Digestible protein (g kgÿ1)
Total lysine (g kgÿ1)
Digestible lysine (g kgÿ1)
Total methionine (g kgÿ1)
Digestible methionine (g kgÿ1)
ME (MJ kg±1)
Crude fibre (g kgÿ1)
Calcium (g kgÿ1)
Av. phosphorus (g kgÿ1)
Level of azolla meal (g kgÿ1)
0 (Control)
50 (TPTAa)
50 (DPDAb)
100 (TPTA)
100 (DPDA)
490
190
115
120
±
65
15
5
+
490
190
95
90
50
65
15
5
+
470
180
110
105
50
65
15
5
+
480
180
65
90
100
65
15
5
+
470
180
70
95
100
65
15
5
+
178.7
156.3
7.87
6.72
3.80
3.42
11.57
47.6
32.1
3.5
174.0
150.2
7.05
5.95
3.48
3.09
11.35
50.6
32.2
3.4
180.9
156.6
7.55
6.36
3.73
3.32
11.33
50.9
32.5
3.5
176.0
150.3
6.88
5.69
3.15
2.74
11.20
53.7
32.3
3.4
178.5
152.6
7.24
5.95
3.44
3.04
11.20
54.7
32.8
3.5
a
TPTA = Total protein and total amino acids.
DPDA = Digestible protein and digestible amino acids.
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12 mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
b
c
determined by the methods of Goering and Van Soest (1970). The starch content of azolla
was determined by the method of Lane and Eynon (1923). Free sugar was estimated by a
colorimetric method (Dubois et al., 1951). Chromic oxide content in feed and excreta was
measured using the method described by Hill and Anderson (1958).
2.7. Statistical analysis
Data were subjected to analysis of variance (Steel and Torrie, 1980) and significant
differences between treatments were identified by least significant difference.
3. Results and discussion
3.1. Chemical composition
Air dried azolla meal was analysed for its nutrient content. It contained dry matter
(905.89 g kgÿ1) which was similar to Ali and Leeson (1995) and Tamang and Samanta
48
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 3
Composition of layer diets containing graded levels of azolla meal (Trial 2)
Ingredients
Wheat
Rice polish
Sesame meal
Full-fat Soybean (Processed)
Azolla meal
Oyster shell
Bone meal
Salt
Soybean oil
L-lysine HCl
DL-methionine
Vitamin mineral premixc
Nutrient Composition (fresh basis)
Crude protein (g kgÿ1)
Digestible protein (g kgÿ1)
Total lysine (g kgÿ1)
Digestible lysine (g kgÿ1)
Total methionine (g kgÿ1)
Digestible methionine (g kgÿ1)
ME (MJ kg±1)
Crude fibre (g kgÿ1)
Calcium (g kgÿ1)
Av. phosphorus (g kgÿ1)
Level of azolla meal (g kgÿ1)
0 (Control)
150 (TPTAa) 150 (DPDAb)
200 (TPTA) 200 (DPDA)
490
190
115
120
±
65
15
5
±
±
±
+
447
160
60
75
150
65
15
5
23
±
±
+
432.45
140
75
90
150
65
15
5
26
0.95
0.60
+
428
145
50
60
200
65
15
5
32
±
±
+
404.9
140
55
80
200
65
15
5
33
1.3
0.8
+
178.7
156.3
7.87
6.72
3.80
3.42
11.57
47.6
32.1
3.5
175.0
148.0
6.41
5.24
3.11
2.67
11.57
56.3
32.8
3.5
182.2
155.3
7.67
6.70
3.89
3.44
11.57
55.8
33.1
3.5
175.0
146.5
6.35
5.14
3.03
2.56
11.57
59.1
33.2
3.5
183.0
154.0
8.00
6.72
3.82
3.42
11.57
59.6
33.4
3.5
a
TPTA = Total protein and total amino acids.
DPDA = Digestible protein and digestible amino acids.
c
Vitamin mineral premix provided per kg diet: vitamin A 12,000 IU; vitamin D3 2000 IU; vitamin E 15 IU;
vitamin K3 2 mg; vitamin B1 1 mg; vitamin B2 4 mg; vitamin B6 3 mg; nicotinic acid 25 mg; pantothenic acid
12 mg; vitamin B12 0.01 mg; folic acid 0.5 mg; biotin 0.05 mg; cobalt 0.4 mg; copper 8 mg; iron 32 mg; iodine
0.05 mg; manganese 64 mg; zinc 40 mg; selenium 0.16 mg; choline chloride 250 mg.
b
(1993). Crude protein (285.4 g kgÿ1) was similar to sesame meal (Rahman, 1992) and
grain legumes (Rahman, 1981). The analysed crude protein content of azolla was similar
to the values reported by Buckingham et al. (1978) and Singh et al. (1983) but higher than
the values reported by others (Tamang and Samanta, 1993; Ali and Leeson, 1995).
Digestible protein (219.8 g kgÿ1) was higher than the values of Tamany et al., (1992) and
Ali and Leeson (1995). Crude fibre (123.8 g kgÿ1) was similar to the values reported by
Sreemannaryana et al. (1993) and Ali and Leeson (1995) but slightly higher than the
values of Subudhi and Singh (1978) and lower than the values of Querubin et al. (1986)
and Tamang and Samanta (1993). ADF (334.1 g kgÿ1) was similar to the values reported
by Buckingham et al. (1978) but lower than those of Tamang and Samanta (1993) and Ali
and Leeson (1995). NDF (445.7 g kgÿ1) was lower than the reported value of others
(Querubin et al., 1986;Tamang and Samanta, 1993; Ali and Leeson, 1995). Ash
(169.2 g kgÿ1)was lower than most reports (Singh et al., 1983; Querubin et al., 1986;
Tamang and Samanta, 1993; Ali and Leeson, 1995) but similar to that of Buckingham
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
49
et al. (1978). The metabolizable energy (7.59 MJ kgÿ1) was comparable to that of duck
weed (Akter, 1995) but higher than reported previously for azolla meal (Ali and Leeson,
1995). These differences indicate that the azolla meal used in these trials was of a higher
quality.
3.2. Egg production
The performance of laying hens in Trial 1 and 2 is shown in Tables 4 and 5
respectively. Feeding azolla meal on a digestible protein and digestible amino acid basis
produced better egg production than with the control diet or diets formulated on a total
protein and total amino acid basis. Hen-day egg production with 50 g kgÿ1 azolla meal
using digestible protein and digestible amino acid was improved by 6.4 and 9.9% over the
control diet and the diet with 50 g kgÿ1 azolla meal on total protein and total amino acids
(Trial 1) while with 100 g kgÿ1 azolla meal on digestible protein and digestible amino
acid egg production improved by 2.0 and 5.7% over the control diet and 100 g kgÿ1
azolla meal on total protein and total amino acid. However, those effects were not
significant at p < 0.05. In Trial 2, hen-day egg production of birds fed 200 g kgÿ1 azolla
meal on total protein and total amino acid was significantly lower than that of hens fed
the control diet or 150 or 200 g kgÿ1 azolla meal on digestible protein and digestible
amino acid basis. These results indicate that azolla meal can be used up to 150 g kgÿ1 on
a total protein and total amino acid basis for laying hen but egg production was reduced at
200 g kgÿ1 level. The results are consistent with those of Bastian (1987) but disagree with
those of Singh and Subudhi (1978). However, when azolla meal was fed at 150 and
200 g kgÿ1 on a digestible protein and digestible amino acid basis egg production
significantly improved by 5.5 and 4.3% over that obtained when azolla meal was fed at
150 and 200 g kgÿ1 on a total protein and total amino acid basis. Better egg production in
diets formulated on digestible protein and digestible amino acid basis might be due to
better precision of diet formulation. These results suggest that azolla meal can replace
sesame meal on a digestible protein and digestible amino acid basis at up to 200 g kgÿ1
diet of laying hens but only to 150 g kgÿ1 diet when the diet is formulated on a total
protein and total amino acid basis.
3.3. Egg mass output
The egg mass output (g egg/day) of hens fed diets with 50 and 100 g kgÿ1 azolla meal
on a digestible protein and digestible amino acid basis improved over the control diet and
diets formulated with a similar level of azolla meal on a total protein and total amino acid
basis (Trial 1). However, the differences were not significant (p > 0.05). At 150 and
200 g kgÿ1 azolla meal fed on a digestible protein and digestible amino acid basis the egg
mass output significantly improved over the control diet and 150 and 200 g kgÿ1 azolla
meal on a total protein and total amino acid basis (Trial 2). The results confirm earlier
observations of improved egg mass output in laying hens when fed diets formulated on
the basis of digestible protein and digestible amino acids (Bougon and Joly, 1990; Joly,
1994).
50
Performance (Mean SE)
Hen-day egg production (%)
Egg mass output (g egg/bird/day)
Feed consumption (g/bird/day)
Feed efficiency
PER
Livability (%)
a
*
Level of azolla meal (g kgÿ1)
0 (Control)
50 (TPTA)
50 (DPDA)
100 (TPTA)
100 (DPDA)
75.7 3.5
49.5 2.5
118.5 2.8
2.42 0.66
28.1 0.3 b
100.0
72.2 0.8
48.3 1.4
118.6 3.6
2.47 0.01
26.4 0.1 c
100.0
82.1 2.2
52.7 1.5
119.4 1.4
2.28 0.04
29.5 0.4 a
100.0
72.0 5.3
47.3 2.6
118.2 2.0
2.52 0.13
26.3 0.3 c
100.0
77.7 1.0
50.9 0.4
119.2 0.4
2.36 0.16
27.9 0.2 b
100.0
Means in the rows bearing similar letters do not differ significantly.
p < 0.05.
CV
(%)
Lsd values and level
of significance
6.3
5.4
3.5
4.13
1.7
NS
NS
NS
NS
1.3*
NS
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 4
Performance of laying hens fed a diet containing 50 or 100 g kgÿ1 azolla meal on the basis of total protein and total amino acids, or digestible protein and digestible
amino acids (Trial 1)a
Performance (Mean SE)
Hen-day production (%)
Egg mass output (g egg/day)
Feed consumption (g/bird/day)
Feed efficiency
PER
Livability (%)
a
*
Level of azolla meal (g kg±1)
0 (Control)
150 (TPTA)
150 (DPDA)
200 (TPTA)
200 (DPDA)
73.5 1.3 ab
39.6 0.7 c
107.3 2.2 c
2.75 0.09 b
25.1 0.9 bc
100.0
70.8 1.3 bc
38.2 1.1 c
112.6 1.5 ab
2.99 0.07 a
23.2 0.6 c
100.0
76.3 0.4 a
44.5 0.2 a
108.2 1.2 bc
2.43 0.03 c
27.5 0.3 a
100.0
69.4 1.1 c
38.9 0.5 c
113.6 0.6 a
2.95 0.03 a
22.9 0.3 c
100.0
73.7 0.9 ab
42.1 0.5 b
107.3 1.3 c
2.56 0.03 c
26.1 0.3 ab
100.0
Means in the rows bearing similar letters do not differ significantly.
p < 0.05. ** p < 0.01.
CV (%)
Lsd values and level
of significance
2.7
3.0
2.9
4.07
4.2
3.0*
1.9*
4.9**
0.16*
2.3*
NS
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 5
Performance of laying hens fed a diet containing 150 or 200 g kgÿ1 azolla meal formulated on the basis of total protein and total amino acids, or digestible protein and
digestible amino acids (Trial 2)a
51
52
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
3.4. Feed consumption
Feed consumption was similar in all dietary treatments in Trial 1 but it significantly
increased for hens fed diets with 150 and 200 g kgÿ1 azolla meal on a total protein and
total amino acids basis compared with hens fed the control diet in Trial 2. Feed
consumption of birds fed diets containing 150 and 200 g kgÿ1 azolla meal on a digestible
protein and digestible amino acid basis was similar to that of birds fed the control diet.
The results partially agree with Querubin et al. (1986) who observed increased feed
consumption of birds fed diets containing up to 150 g kgÿ1 azolla meal on a total protein
and total amino acid basis but they disagree with those of Bastian (1987).
3.5. Feed efficiency
It is evident from Tables 4 and 5 that better feed efficiencies were found when azolla
meal was fed at 50 and 100 g kgÿ1 (Trial 1) but significantly improved over the control
when fed at 150 and 200 g kgÿ1 when formulated on a digestible protein and digestible
amino acid basis (Trial 2) but it was poorer when the diets were formulated on a total
protein and total amino acid basis. Improved feed efficiency in diets formulated on a
digestible nutrient basis is mainly due to better egg production. The results are similar to
earlier observations (Bougon and Joly, 1990; Johnson, 1992; Joly, 1994) of higher feed
efficiency when fed on a digestible nutrient basis and confirm the reduced feed efficiency
found in a broiler study (Querubin et al., 1986) when they were formulated on a total
protein and total amino acids basis.
3.6. Protein efficiency ratio
Protein efficiency ratio (PER) improved (p < 0.05) for the 50 and 150 g kgÿ1 azolla
meal diet formulated on the basis of digestible protein and digestible amino acid
compared with the PER of the control diet or the diets with a similar level of azolla meal
and formulated on the basis of total protein and total amino acid (Tables 4 and 5). PER for
100 and 200 g azolla meal on a digestible protein and digestible amino acid basis
improved (p < 0.05) when compared to similar levels of azolla meal on a total protein and
total amino acid basis but was similar to the control diet. Feeding azolla meal on a
digestible protein and digestible amino acid basis maintained or improved protein
efficiency but it was significantly reduced when fed on total protein and total amino acid
basis.
3.7. Livability
No bird died in any treatment during the experiments indicating that azolla meal had no
deleterious effect on livability. The results were consistent with Singh and Subudhi
(1978) and Castillo et al. (1981) who found no effect on the livability of chicks and
broilers.
Egg quality
Egg weight (g)
Yolk
Colour
Score
a
*
Experiment
No.
28-dayPeriod/week
Levels of azolla meal (g kgÿ1)
0 (Control)
50/150
(TPTA)
50/150
(DPDA)
100/200
(TPTA)
100/200
(DPDA)
CV
(%)
Lsd
values and level
of significance
1
1
1
1
1
1st
2nd
3rd
4th
Mean
62.1 0.5
65.0 0.7
67.0 0.7
67.0 1.0
65.3 0.7
63.3 0.8
66.9 0.7
68.7 1.2
68.9 1.5
67.0 1.2
61.9 1.5
63.9 1.0
65.9 1.2
65.4 1.2
64.3 1.1
62.6 2.1
65.6 2.9
67.4 3.1
67.4 3.3
65.8 2.8
63.1 0.7
65.2 0.8
67.4 0.8
66.1 0.4
65.5 0.6
0.5
4.5
4.4
4.9
4.2
NS
NS
NS
NS
NS
2
2
2
1st
2nd
Mean
54.5 0.6 b
56.6 0.7 b
55.6 0.6 b
53.6 0.8 b
53.4 0.4 c
54.3 0.6 c
56.4 0.6 a
58.8 0.5 a
57.6 0.4 a
54.3 0.5 b
55.7 0.6 b
55.0 0.6 b
56.3 0.2 a
57.6 0.7 ab
57.0 0.4 ab
2.2
2.2
2.0
1.8**
1.9**
1.3**
1
1
1
1
1
Starting
4th week
8th week
12th week
16th week
1.3 0.2
0.7 0.1
1.0 0.0
1.0 0.0
1.3 0.3
2.0 0.1
2.4 0.3
3.0 0.3
3.3 0.1
3.8 0.3
1.8 0.2
2.4 0.5
2.7 0.3
3.3 0.1
3.5 0.5
2.3 0.1
3.4 0.3
4.0 0.2
4.6 0.2
5.4 0.3
a
a
a
a
a
24.4
27.3
13.9
10.1
14.0
0.6*
0.9*
0.6*
0.5*
0.9*
2
2
4th week
8th week
1.3 0.1 c
1.3 0.1 c
9.1 0.3 a
9.6 0.4 a
7.2
10.5
1.5*
1.1*
c
c
d
c
c
Values in the rows bearing similar letters do not differ significantly.
p < 0.05. ** p < 0.01.
b
b
c
b
b
7.0 0.5 b
8.1 0.2 b
b
b
c
b
b
6.8 0.3 b
8.1 0.3 b
ab
a
b
a
a
8.9 0.2 a
8.9 0.1 ab
2.7 0.1
3.7 0.2
4.9 0.1
5.0 0.1
5.2 0.2
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
Table 6
Egg quality characteristics of laying hens fed diets containing azolla meal formulated on the basis of total protein and total amino acids, or on digestible protein and
digestible amino acids basis (Trials 1 and 2)a
53
54
A. Khatun et al. / Animal Feed Science and Technology 81 (1999) 43±56
3.8. Egg quality
The external and internal characteristics of eggs in feeding Trials 1 and 2 are presented
in Table 6. It is evident that, apart from egg weight and yolk colour, egg quality
characteristics were not affected by the dietary treatments. Feeding azolla meal on a
digestible protein and digestible amino acid basis improved egg weight (Trial 2). The
improved egg size for diets formulated on a digestible nutrient basis might be due to
better critical amino acid balance (Morris and Gous, 1988). The results were similar to
the earlier observations of Bougon and Joly (1990) and Joly (1994). The yolk colour
significantly improved with increasing levels of azolla meal and period of feeding
whether fed on a total or on a digestible protein and amino acid basis. These results were
similar to the observations of Singh and Subudhi (1978) and Bastian (1987).
The results of our study indicated that azolla meal was a fair source of plant protein
and metabolizable energy for laying hens. When azolla meal replaced sesame meal (wt./
wt.) on a digestible protein and digestible amino acid basis performance was improved
over that obtained when the replacement was on the basis of total protein and amino
acids.
Acknowledgements
We gratefully acknowledge the provision of facilities by the Department of Poultry
Science, Bangladesh Agricultural University, Mynensingh, Bangladesh. The help of Mr.
S. C. Das during the experiments is greatly appreciated.
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