Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol83.Issue3-4.Mar2000:
Animal Feed Science and Technology
83 (2000) 237±247
Effects of Spirulina platensis on growth
performance of weanling pigs$
G.S. Grinstead, M.D. Tokach, S.S. Dritz*,1,
R.D. Goodband, J.L. Nelssen
Department of Animal Sciences and Industry, Kansas State University,
Manhattan, KS 66506-0201, USA
Received 5 May 1999; received in revised form 8 October 1999; accepted 17 November 1999
Abstract
Three experiments were conducted to evaluate the in¯uence of an algae derived feed additive,
Spirulina platensis (SP), on weanling pig performance. In all experiments, pigs were blocked by
weight and allotted to one of four (experiments 1 and 3) or six (Experiment 2) dietary treatments.
Standard diets and feeding regimens were implemented in all three experiments and SP replaced
soybean meal on an equal lysine basis. Zinc oxide (3000 mg Zn kgÿ1) and medication were
included in the diets for only experiments 1 and 3. In Experiment 1, a control diet or diets
containing 2, 5, or 20 g SP kgÿ1 were fed in a pellet form from days 0 to 14 after weaning followed
by meal form from days 14 to 28 after weaning. From days 0 to 14, no differences in pig
performance were observed. From days 14 to 28, a cubic (p < 0.05) response was observed for ADG
and ADFI with pigs fed 20 g SP kgÿ1 having greater ADG than pigs fed the control diet. In
Experiment 2, dietary treatments (meal form) consisted of a control diet (no SP, fed for 6 weeks),
1 g SP kgÿ1 (fed for 6 weeks) or 2 g SP kgÿ1 (fed for 1, 2, 4, or 6 weeks). Pigs were switched to the
control diet at the end of each SP feeding regimen. From days 0 to 14 after weaning, no differences
in ADG or ADFI were observed. Pigs fed diets containing 1 or 2 g SP kgÿ1 for the entire 28 days
had better feed ef®ciency (p < 0.02) than the treatments in which SP had been removed from the
diet on day 7 or 14 after weaning. However, from days 0 to 42 after weaning, no differences in ADG
or ADFI were observed. In Experiment 3, dietary treatments were arranged in a 2 2 factorial with
the main effects of feed processing (meal versus pellet) with or without 2 g SP kgÿ1. From days 0 to
14 after weaning, adding SP to pelleted diets numerically tended to decrease ADG (SP feed
$
Contribution No. 99-360-J of the Kansas Agric. Exp. Sta., Manhattan 66506.
Corresponding author. Tel.: 1-785-532-4202; fax: 1-603-676-5543.
E-mail address: dritz@vet.ksu.edu (S.S. Dritz).
1
Food Animal and Health Management Center, College of Veterinary Medicine, Kansas State University,
Manhattan 66506-5606.
*
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 1 3 0 - 3
238
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
processing, p < 0.10), whereas adding SP to meal diets tended to improve ADG. From days 14 to 28
or days 0 to 28 after weaning, no differences in ADG, ADFI, or F/G were observed. In conclusion,
the response to SP was inconsistent and occurred only with meal diets. # 2000 Elsevier Science
B.V. All rights reserved.
Keywords: Pigs; Algae; Performance
1. Introduction
Two-thirds of the Earth's biomass is comprised of more than 25 000 species of algae
(Henrikson, 1997). Historians have discovered that alga were a major dietary component
of ancient cultures and are still consumed by people today (Kay, 1991). Algae can be
grouped into two categories: macroalgae (seaweeds); and microalgae (e.g. Chorella spp.
and Spirulina spp.). Both classes of algae are used for human food, animal feed,
fertilizers, biochemicals, and the development of pharmaceuticals (Henrikson, 1997).
Microalgae are considered as a suitable nutriental supplement because of their high
protein content (500±700 g CP/kg) and their abundance of vitamins and minerals (Kay,
1991). Spirulina platensis (SP) are a species of microalga that have not been evaluated
widely in animal feeding studies.
Spirulina platensis are grown organically in specialized ponds to provide a product that
is free of contaminants (Henrikson, 1997). Qureshi (1995) observed that young poults fed
1000 to 10 000 ppm SP had heavier spleen and thymus weights than poults fed a control
diet. Chicks fed SP also exhibited a higher clearance rate of Escherichia coli (intravenous
inoculation) from their circulation than did chicks fed a basal diet (Qureshi, 1995). Yap et
al. (1982) conducted an experiment replacing dried skim milk with Spirulina maxima.
Pigs fed high levels of S. maxima (140 g/kg diet) had similar performance as those fed the
diet containing skim milk.
Based on its potential to enhance growth, these experiments were designed to evaluate
the effect of dietary SP on weanling pig performance.
2. Materials and methods
2.1. Animal care and use
The experimental protocols used in these studies were approved by the Kansas State
University Institutional Animal Use Committee.
2.2. Animals and housing
Three experiments were conducted to evaluate the effects of SP on weanling pig
performance. Pigs (PIC, L326 C22) used in experiments 1 and 3 were reared in a
commercial swine operation in northeast Kansas. At weaning, pigs were placed in an
environmentally controlled nursery, in pens (1.2 1.5 m) with two nipple waterers, a six-
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
239
hole feeder, and woven wire ¯ooring. In Experiment 2, pigs (PIC, L42 L19) were
obtained from a closed production system located in central Kansas. Pigs were
transported in an enclosed stock trailer for 1 h without access to feed or water. They
were housed in an all-in-all-out, off-site, environmentally regulated, nursery facility
located a minimum of 0.8 km from other pig-rearing sites at Kansas State University. Pigs
were weighed on arrival and then allotted to their respective pens. Each pen
(1.2 m 1.2 m) contained one nipple waterer, a ®ve-hole feeder, and metal bar ¯ooring.
Nurseries were maintained at 348C for the ®rst week after weaning. Temperature was
reduced by 1.58C each week, and air ¯ow was regulated to maintain pig comfort. Animals
were provided ab libitum access to feed and water for the duration of the experiments.
2.3. Experiment 1
A total of 203 pigs (initially 3.7 0.85 kg and 11±12 days of age) were used in a 28day growth trial. Pigs were blocked by weight and allotted randomly to one of four
dietary treatments. There were eight or nine pigs/pen and six pens/treatment. In
formulating diets, the amino acid values for SP were provided by the supplier (Table 1)
and NRC (1988) values for soybean meal were used. The trial was divided into three
phases to approximate a nutritional program similar to that used in commercial
production. Three diets were used; the ®rst was fed from days 0 to 7 after weaning, the
second from days 7 to 14 after weaning, and the third from days 14 to 28 after weaning.
Pigs remained on their respective dietary treatments in all three phases.
All diets were maize±soybean meal based. The days 0±7 and 7±14 diets were fed in
pellet form (4 mm diameter; Table 2). The diets fed from days 14 to 28 were fed in a meal
form. Spirulina platensis (2, 5, and 20 g kgÿ1) replaced soybean meal on an equal lysine
Table 1
Composition of Spirulina platensisa
Item (g kgÿ1)
Spirulina platensisb
Protein
Fat
620 (610)
55
Amino acids
Arginine
Cystine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Tyrosine
Valine
a
b
43 (39)
6 (7)
10 (10)
35 (32)
54 (51)
29 (27)
14 (14)
28 (26)
32 (28)
9 (6)
30 (24)
40 (36)
Values shown on an as-fed basis.
Amino acid levels provided by the supplier, and analyzed values are provided in parentheses.
240
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
Table 2
Composition of basal diets (as-fed basis)
Dietary phases
Days 0±7a
Days 7±14b
Days 14±28c
Days 28±42d
Ingredient (g kgÿ1)
Maize
Dried whey
Soybean meale
Spray-dried animal plasma
Select menhaden ®sh meal
Soybean oil
Lactose
Spray-dried blood meal
Antibioticf
Monocalcium phosphate
Limestone
Zinc oxideg
Premixh
Salt
L-Lysine HCl
DL-Methionine
335.6
250.0
124.7
67.0
60.0
60.0
50.0
17.5
10.0
7.6
4.8
3.8
4.0
2.0
1.5
1.5
399.2
200.0
232.4
25.0
25.0
50.0
±
25.0
10.0
12.8
7.5
3.8
4.0
2.5
1.5
1.3
581.7
100.0
245.6
±
±
±
±
25.0
10.0
16.4
10.0
2.5
4.0
2.5
1.5
0.8
660.4
±
305.4
±
±
±
±
±
±
15.4
9.7
±
4.0
3.5
1.5
0.1
Chemical analysis (g kgÿ1)i
Experiment 1
Experiment 2
Experiment 3
223
218
222
224
228
220
206
200
200
±
203
±
a
Formulated to contain g per kg of diet: lysine 17, methionine 4.8, Ca 9, and P 8.
Formulated to contain g per kg of diet: lysine 16, methionine 4.4, Ca 9, and P 8.
c
Formulated to contain g per kg of diet: lysine 13, methionine 3.6, Ca 8.5, and P 7.5.
d
Formulated to contain g per kg of diet: lysine 12, methionine 3.2, Ca 7.5, and P 7 (Experiment 2).
e
Spirulina platensis replaced soybean meal on an equal lysine basis.
f
Provided 55 mg carbadox kgÿ1 experiments 1 and 3. In Experiment 2, additional maize replaced the
antibiotic.
g
Only included in experiments 1 and 3 to provide 3000 (days 0±14) or 2000 (days 14±28) mg Zn kgÿ1
of diet.
h
Premix provided per kilogram of complete diet: Mn, 40 mg; Fe, 165 mg; Zn, 165 mg; Cu, 16 mg; I, 0.3 mg;
Se, 0.3 mg; vitamin A, 11 025 IU; vitamin D3, 1103 IU; vitamin E, 44 IU; menadione (menadione sodium
bisulfate complex) 4.4 mg; ribo¯avin, 9.9 mg; d-pantothenic acid, 33 mg; niacin, 55 mg; choline, 166 mg; and
vitamin B12, 0.04 mg.
i
Values for each respective diet represent the mean of all treatments.
b
basis in the control diet to provide the additional experimental treatments. All diets
contained a medication (carbodox, 55 mg kgÿ1) and 3000 mg kgÿ1 (days 0±14) or
2000 mg Zn kgÿ1 (days 14±28) from zinc oxide for growth promotion. The pelleted diets
(experiments 1 and 3) were conditioned with a 10 s retention time at 608C using a Master
Model HD 1000 series California Pellet Mill equipped with a 3.2 cm effective thickness
die. The corresponding pellet exit temperatures averaged 688C. Average daily gain
(ADG), average daily feed intake (ADFI), and feed ef®ciency (F/G) were determined by
weighing pigs and measuring feed disappearance on days 7, 14, 21, and 28 after weaning.
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
241
2.4. Experiment 2
A total of 180 weanling pigs (initially 5.6 0.75 kg and 18 2 days of age) was used
in a 42-day growth trial to examine the effect of duration of SP feeding on growth
performance. Pigs were blocked by weight and allotted randomly to one of six dietary
treatments. There were ®ve pigs/pen and six pens/treatment. The trial was divided into
four phases: days 0±7, 7±14, 14±28, and 28±42 after weaning. Dietary treatments
consisted of a control diet (no SP) fed for 6 weeks; 1 g SP kgÿ1 fed for 6 weeks; and 2 g
SP kgÿ1 fed for 1, 2, 4, or 6 weeks. At the end of each SP feeding regimen, pigs were
switched to the control diet and remained on it for the remainder of the experiment.
The basal diets used for each phase were similar to those used in Experiment 1. The
days 28±42 diet was maize±soybean meal-based diet formulated to 12 g total lysine kgÿ1
and did not contain any specialty protein sources. All diets fed in this experiment were in
a meal form and did not contain growth promotional levels of Zn or a feed medication.
Average daily gain, ADFI, and feed ef®ciency were determined by weighing pigs and
measuring feed disappearance on days 7, 14, 21, 28, 35, and 42 after weaning.
2.5. Experiment 3
A total of 192 weanling pigs (initially 4.0 0.64 kg and 11±12 days of age) was used
in a 28-day growth trial. This experiment was designed to examine the effects of SP fed in
pelleted or meal-based diets on pig performance. Pigs were blocked by weight and
allotted randomly to one of four dietary treatments. There were eight pigs/pen and six
pens/treatment. The facilities, basal diets, feeding regimen, and experimental procedures
were the same as those used in Experiment 1. Pigs were fed a control diet or diets
containing 2 g SP kgÿ1 replacing soybean meal on an equal lysine basis. Both diets were
fed in pellet and meal forms.
2.6. Chemical analysis
Samples of SP were collected and analyzed for amino acid concentrations (Table 1)
using ion exchange chromatography following acid hydrolysis (Knabe et al., 1989).
Methionine and cystine were determined following oxidation with performic acid
(Moore, 1963). Tryptophan was determined following alkaline hydrolysis (LaRue, 1985).
Analyzed values were similar to the nutrient values provided by the supplier that were
used in diet formulation. Amino acid values for soybean meal (475 g CP kgÿ1) were
derived from published values (NRC, 1988). The amino acid pro®le of SP appears to be
similar to that of soybean meal. All experimental diets were sampled and analyzed for
crude protein (CP) (AOAC, 1990). Analyzed values were similar to calculated values
(Table 2).
2.7. Statistical analysis
All experiments were analyzed as randomized complete block designs. Pigs were
blocked by initial body weight and the pen was the experimental unit. Analysis of
242
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
variance was performed using the GLM procedures of SAS (1998). In Experiment 1,
linear, quadratic, and cubic polynomials (Peterson, 1985) were evaluated for increasing
levels of SP. In Experiment 2, data were analyzed as the mean of each SP level and the
lengths of time each was fed. Treatment means were separated using the LSD test, which
was protected by requiring rejection of experiment wide F-tests ( < 0.05) before
application (Steel and Torrie, 1980). Experiment 3 was analyzed as a 2 2 factorial with
the main effects of feed processing (meal or pellet) with or without 2 g SP kgÿ1 and their
interaction.
3. Results and discussion
Previous studies have evaluated higher inclusions (up to 330 g kgÿ1) of microalgae as a
protein replacement for soybean meal in weanling pig diets (Rigor et al., 1980; Yap et al.,
1982; Hugh et al., 1985). The current study was conducted using low inclusions of SP
because of the improvement in performance observed with low levels in poultry trials by
Qureshi et al. (1996) and the fact that little research has been conducted with these lower
levels in weanling pigs. The analyzed amino acid values of the SP used in this experiment
were in general agreement with the values used in diet formulation (Table 1). This
indicates that the low inclusion levels of SP used in the experiment had little effect on the
amino acid balance of the diets used in the experiments.
3.1. Experiment 1
From days 0 to 7 and days 0 to 14 after weaning, increasing SP had no effect on growth
performance relative to that of pigs fed the control diet (Table 3). From days 7 to 14 after
weaning, no differences in ADG were observed. However, ADFI numerically increased,
decreased, and then increased again (cubic, p < 0.10) in response to increasing SP. Feed
ef®ciency tended to become poorer (linear, p < 0.10) with increasing SP.
From days 14 to 28 after weaning, ADG and ADFI responded in a cubic (p < 0.05)
fashion as SP increased. Pigs fed 2 g SP kgÿ1 had the best ADG which was greater than
those fed the control diet or diet containing 5 g SP kgÿ1. Daily feed intake was greatest
for pigs fed either 2 or 20 g SP kgÿ1 compared with those fed 5 g SP kgÿ1, with those fed
the control diet having intermediate ADFI. Feed ef®ciency was not affected.
For the entire experimental period (days 0±28 after weaning), ADG tend to (cubic,
p < 0.08) and ADFI (cubic, p < 0.05) increased, decreased, and then increased again with
increasing SP (Table 3). Feed ef®ciency was unaffected by SP.
All diets were pelleted during the ®rst two weeks of the experiment. During the second
half of the experiment, days 14±28, pigs fed 2 g SP kgÿ1 had increased ADG compared
with those fed the control diet. The cubic response in growth and feed intake happened to
coincide with the feeding of meal-based diets. It was speculated that high temperatures
associated with the pelleting process may have damaged or inactivated the SP. Similar
heat stability problems have been observed in pig diets with supplemental enzymes or
probiotics that have been subjected to thermal processing (Gunther, 1986; Swanson and
Hancock, 1989; Maloney et al., 1998).
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
243
Table 3
Effect of increasing Spirulina platensis on weanling pig performance (Experiment 1)a
Item
Spirulina plantensis (g kgÿ1)
SEM
0
2
5
20
Days 0±7
ADG (g)
ADFI (g)
F/G
127
144
1.14
113
139
1.22
122
145
1.18
140
151
1.07
Days 7±14
ADG (g)
ADFI (g)
F/G
223
239
1.07
238
264
1.10
214
246
1.14
Days 0±14
ADG (g)
ADFI (g)
F/G
175
192
1.09
176
201
1.14
Days 14±28
ADG (g)
ADFI (g)
F/G
288
460
1.60
Days 0±28
ADG (g)
ADFI (g)
F/G
231
326
1.40
Probability (P
83 (2000) 237±247
Effects of Spirulina platensis on growth
performance of weanling pigs$
G.S. Grinstead, M.D. Tokach, S.S. Dritz*,1,
R.D. Goodband, J.L. Nelssen
Department of Animal Sciences and Industry, Kansas State University,
Manhattan, KS 66506-0201, USA
Received 5 May 1999; received in revised form 8 October 1999; accepted 17 November 1999
Abstract
Three experiments were conducted to evaluate the in¯uence of an algae derived feed additive,
Spirulina platensis (SP), on weanling pig performance. In all experiments, pigs were blocked by
weight and allotted to one of four (experiments 1 and 3) or six (Experiment 2) dietary treatments.
Standard diets and feeding regimens were implemented in all three experiments and SP replaced
soybean meal on an equal lysine basis. Zinc oxide (3000 mg Zn kgÿ1) and medication were
included in the diets for only experiments 1 and 3. In Experiment 1, a control diet or diets
containing 2, 5, or 20 g SP kgÿ1 were fed in a pellet form from days 0 to 14 after weaning followed
by meal form from days 14 to 28 after weaning. From days 0 to 14, no differences in pig
performance were observed. From days 14 to 28, a cubic (p < 0.05) response was observed for ADG
and ADFI with pigs fed 20 g SP kgÿ1 having greater ADG than pigs fed the control diet. In
Experiment 2, dietary treatments (meal form) consisted of a control diet (no SP, fed for 6 weeks),
1 g SP kgÿ1 (fed for 6 weeks) or 2 g SP kgÿ1 (fed for 1, 2, 4, or 6 weeks). Pigs were switched to the
control diet at the end of each SP feeding regimen. From days 0 to 14 after weaning, no differences
in ADG or ADFI were observed. Pigs fed diets containing 1 or 2 g SP kgÿ1 for the entire 28 days
had better feed ef®ciency (p < 0.02) than the treatments in which SP had been removed from the
diet on day 7 or 14 after weaning. However, from days 0 to 42 after weaning, no differences in ADG
or ADFI were observed. In Experiment 3, dietary treatments were arranged in a 2 2 factorial with
the main effects of feed processing (meal versus pellet) with or without 2 g SP kgÿ1. From days 0 to
14 after weaning, adding SP to pelleted diets numerically tended to decrease ADG (SP feed
$
Contribution No. 99-360-J of the Kansas Agric. Exp. Sta., Manhattan 66506.
Corresponding author. Tel.: 1-785-532-4202; fax: 1-603-676-5543.
E-mail address: dritz@vet.ksu.edu (S.S. Dritz).
1
Food Animal and Health Management Center, College of Veterinary Medicine, Kansas State University,
Manhattan 66506-5606.
*
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 1 3 0 - 3
238
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
processing, p < 0.10), whereas adding SP to meal diets tended to improve ADG. From days 14 to 28
or days 0 to 28 after weaning, no differences in ADG, ADFI, or F/G were observed. In conclusion,
the response to SP was inconsistent and occurred only with meal diets. # 2000 Elsevier Science
B.V. All rights reserved.
Keywords: Pigs; Algae; Performance
1. Introduction
Two-thirds of the Earth's biomass is comprised of more than 25 000 species of algae
(Henrikson, 1997). Historians have discovered that alga were a major dietary component
of ancient cultures and are still consumed by people today (Kay, 1991). Algae can be
grouped into two categories: macroalgae (seaweeds); and microalgae (e.g. Chorella spp.
and Spirulina spp.). Both classes of algae are used for human food, animal feed,
fertilizers, biochemicals, and the development of pharmaceuticals (Henrikson, 1997).
Microalgae are considered as a suitable nutriental supplement because of their high
protein content (500±700 g CP/kg) and their abundance of vitamins and minerals (Kay,
1991). Spirulina platensis (SP) are a species of microalga that have not been evaluated
widely in animal feeding studies.
Spirulina platensis are grown organically in specialized ponds to provide a product that
is free of contaminants (Henrikson, 1997). Qureshi (1995) observed that young poults fed
1000 to 10 000 ppm SP had heavier spleen and thymus weights than poults fed a control
diet. Chicks fed SP also exhibited a higher clearance rate of Escherichia coli (intravenous
inoculation) from their circulation than did chicks fed a basal diet (Qureshi, 1995). Yap et
al. (1982) conducted an experiment replacing dried skim milk with Spirulina maxima.
Pigs fed high levels of S. maxima (140 g/kg diet) had similar performance as those fed the
diet containing skim milk.
Based on its potential to enhance growth, these experiments were designed to evaluate
the effect of dietary SP on weanling pig performance.
2. Materials and methods
2.1. Animal care and use
The experimental protocols used in these studies were approved by the Kansas State
University Institutional Animal Use Committee.
2.2. Animals and housing
Three experiments were conducted to evaluate the effects of SP on weanling pig
performance. Pigs (PIC, L326 C22) used in experiments 1 and 3 were reared in a
commercial swine operation in northeast Kansas. At weaning, pigs were placed in an
environmentally controlled nursery, in pens (1.2 1.5 m) with two nipple waterers, a six-
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
239
hole feeder, and woven wire ¯ooring. In Experiment 2, pigs (PIC, L42 L19) were
obtained from a closed production system located in central Kansas. Pigs were
transported in an enclosed stock trailer for 1 h without access to feed or water. They
were housed in an all-in-all-out, off-site, environmentally regulated, nursery facility
located a minimum of 0.8 km from other pig-rearing sites at Kansas State University. Pigs
were weighed on arrival and then allotted to their respective pens. Each pen
(1.2 m 1.2 m) contained one nipple waterer, a ®ve-hole feeder, and metal bar ¯ooring.
Nurseries were maintained at 348C for the ®rst week after weaning. Temperature was
reduced by 1.58C each week, and air ¯ow was regulated to maintain pig comfort. Animals
were provided ab libitum access to feed and water for the duration of the experiments.
2.3. Experiment 1
A total of 203 pigs (initially 3.7 0.85 kg and 11±12 days of age) were used in a 28day growth trial. Pigs were blocked by weight and allotted randomly to one of four
dietary treatments. There were eight or nine pigs/pen and six pens/treatment. In
formulating diets, the amino acid values for SP were provided by the supplier (Table 1)
and NRC (1988) values for soybean meal were used. The trial was divided into three
phases to approximate a nutritional program similar to that used in commercial
production. Three diets were used; the ®rst was fed from days 0 to 7 after weaning, the
second from days 7 to 14 after weaning, and the third from days 14 to 28 after weaning.
Pigs remained on their respective dietary treatments in all three phases.
All diets were maize±soybean meal based. The days 0±7 and 7±14 diets were fed in
pellet form (4 mm diameter; Table 2). The diets fed from days 14 to 28 were fed in a meal
form. Spirulina platensis (2, 5, and 20 g kgÿ1) replaced soybean meal on an equal lysine
Table 1
Composition of Spirulina platensisa
Item (g kgÿ1)
Spirulina platensisb
Protein
Fat
620 (610)
55
Amino acids
Arginine
Cystine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Tyrosine
Valine
a
b
43 (39)
6 (7)
10 (10)
35 (32)
54 (51)
29 (27)
14 (14)
28 (26)
32 (28)
9 (6)
30 (24)
40 (36)
Values shown on an as-fed basis.
Amino acid levels provided by the supplier, and analyzed values are provided in parentheses.
240
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
Table 2
Composition of basal diets (as-fed basis)
Dietary phases
Days 0±7a
Days 7±14b
Days 14±28c
Days 28±42d
Ingredient (g kgÿ1)
Maize
Dried whey
Soybean meale
Spray-dried animal plasma
Select menhaden ®sh meal
Soybean oil
Lactose
Spray-dried blood meal
Antibioticf
Monocalcium phosphate
Limestone
Zinc oxideg
Premixh
Salt
L-Lysine HCl
DL-Methionine
335.6
250.0
124.7
67.0
60.0
60.0
50.0
17.5
10.0
7.6
4.8
3.8
4.0
2.0
1.5
1.5
399.2
200.0
232.4
25.0
25.0
50.0
±
25.0
10.0
12.8
7.5
3.8
4.0
2.5
1.5
1.3
581.7
100.0
245.6
±
±
±
±
25.0
10.0
16.4
10.0
2.5
4.0
2.5
1.5
0.8
660.4
±
305.4
±
±
±
±
±
±
15.4
9.7
±
4.0
3.5
1.5
0.1
Chemical analysis (g kgÿ1)i
Experiment 1
Experiment 2
Experiment 3
223
218
222
224
228
220
206
200
200
±
203
±
a
Formulated to contain g per kg of diet: lysine 17, methionine 4.8, Ca 9, and P 8.
Formulated to contain g per kg of diet: lysine 16, methionine 4.4, Ca 9, and P 8.
c
Formulated to contain g per kg of diet: lysine 13, methionine 3.6, Ca 8.5, and P 7.5.
d
Formulated to contain g per kg of diet: lysine 12, methionine 3.2, Ca 7.5, and P 7 (Experiment 2).
e
Spirulina platensis replaced soybean meal on an equal lysine basis.
f
Provided 55 mg carbadox kgÿ1 experiments 1 and 3. In Experiment 2, additional maize replaced the
antibiotic.
g
Only included in experiments 1 and 3 to provide 3000 (days 0±14) or 2000 (days 14±28) mg Zn kgÿ1
of diet.
h
Premix provided per kilogram of complete diet: Mn, 40 mg; Fe, 165 mg; Zn, 165 mg; Cu, 16 mg; I, 0.3 mg;
Se, 0.3 mg; vitamin A, 11 025 IU; vitamin D3, 1103 IU; vitamin E, 44 IU; menadione (menadione sodium
bisulfate complex) 4.4 mg; ribo¯avin, 9.9 mg; d-pantothenic acid, 33 mg; niacin, 55 mg; choline, 166 mg; and
vitamin B12, 0.04 mg.
i
Values for each respective diet represent the mean of all treatments.
b
basis in the control diet to provide the additional experimental treatments. All diets
contained a medication (carbodox, 55 mg kgÿ1) and 3000 mg kgÿ1 (days 0±14) or
2000 mg Zn kgÿ1 (days 14±28) from zinc oxide for growth promotion. The pelleted diets
(experiments 1 and 3) were conditioned with a 10 s retention time at 608C using a Master
Model HD 1000 series California Pellet Mill equipped with a 3.2 cm effective thickness
die. The corresponding pellet exit temperatures averaged 688C. Average daily gain
(ADG), average daily feed intake (ADFI), and feed ef®ciency (F/G) were determined by
weighing pigs and measuring feed disappearance on days 7, 14, 21, and 28 after weaning.
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
241
2.4. Experiment 2
A total of 180 weanling pigs (initially 5.6 0.75 kg and 18 2 days of age) was used
in a 42-day growth trial to examine the effect of duration of SP feeding on growth
performance. Pigs were blocked by weight and allotted randomly to one of six dietary
treatments. There were ®ve pigs/pen and six pens/treatment. The trial was divided into
four phases: days 0±7, 7±14, 14±28, and 28±42 after weaning. Dietary treatments
consisted of a control diet (no SP) fed for 6 weeks; 1 g SP kgÿ1 fed for 6 weeks; and 2 g
SP kgÿ1 fed for 1, 2, 4, or 6 weeks. At the end of each SP feeding regimen, pigs were
switched to the control diet and remained on it for the remainder of the experiment.
The basal diets used for each phase were similar to those used in Experiment 1. The
days 28±42 diet was maize±soybean meal-based diet formulated to 12 g total lysine kgÿ1
and did not contain any specialty protein sources. All diets fed in this experiment were in
a meal form and did not contain growth promotional levels of Zn or a feed medication.
Average daily gain, ADFI, and feed ef®ciency were determined by weighing pigs and
measuring feed disappearance on days 7, 14, 21, 28, 35, and 42 after weaning.
2.5. Experiment 3
A total of 192 weanling pigs (initially 4.0 0.64 kg and 11±12 days of age) was used
in a 28-day growth trial. This experiment was designed to examine the effects of SP fed in
pelleted or meal-based diets on pig performance. Pigs were blocked by weight and
allotted randomly to one of four dietary treatments. There were eight pigs/pen and six
pens/treatment. The facilities, basal diets, feeding regimen, and experimental procedures
were the same as those used in Experiment 1. Pigs were fed a control diet or diets
containing 2 g SP kgÿ1 replacing soybean meal on an equal lysine basis. Both diets were
fed in pellet and meal forms.
2.6. Chemical analysis
Samples of SP were collected and analyzed for amino acid concentrations (Table 1)
using ion exchange chromatography following acid hydrolysis (Knabe et al., 1989).
Methionine and cystine were determined following oxidation with performic acid
(Moore, 1963). Tryptophan was determined following alkaline hydrolysis (LaRue, 1985).
Analyzed values were similar to the nutrient values provided by the supplier that were
used in diet formulation. Amino acid values for soybean meal (475 g CP kgÿ1) were
derived from published values (NRC, 1988). The amino acid pro®le of SP appears to be
similar to that of soybean meal. All experimental diets were sampled and analyzed for
crude protein (CP) (AOAC, 1990). Analyzed values were similar to calculated values
(Table 2).
2.7. Statistical analysis
All experiments were analyzed as randomized complete block designs. Pigs were
blocked by initial body weight and the pen was the experimental unit. Analysis of
242
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
variance was performed using the GLM procedures of SAS (1998). In Experiment 1,
linear, quadratic, and cubic polynomials (Peterson, 1985) were evaluated for increasing
levels of SP. In Experiment 2, data were analyzed as the mean of each SP level and the
lengths of time each was fed. Treatment means were separated using the LSD test, which
was protected by requiring rejection of experiment wide F-tests ( < 0.05) before
application (Steel and Torrie, 1980). Experiment 3 was analyzed as a 2 2 factorial with
the main effects of feed processing (meal or pellet) with or without 2 g SP kgÿ1 and their
interaction.
3. Results and discussion
Previous studies have evaluated higher inclusions (up to 330 g kgÿ1) of microalgae as a
protein replacement for soybean meal in weanling pig diets (Rigor et al., 1980; Yap et al.,
1982; Hugh et al., 1985). The current study was conducted using low inclusions of SP
because of the improvement in performance observed with low levels in poultry trials by
Qureshi et al. (1996) and the fact that little research has been conducted with these lower
levels in weanling pigs. The analyzed amino acid values of the SP used in this experiment
were in general agreement with the values used in diet formulation (Table 1). This
indicates that the low inclusion levels of SP used in the experiment had little effect on the
amino acid balance of the diets used in the experiments.
3.1. Experiment 1
From days 0 to 7 and days 0 to 14 after weaning, increasing SP had no effect on growth
performance relative to that of pigs fed the control diet (Table 3). From days 7 to 14 after
weaning, no differences in ADG were observed. However, ADFI numerically increased,
decreased, and then increased again (cubic, p < 0.10) in response to increasing SP. Feed
ef®ciency tended to become poorer (linear, p < 0.10) with increasing SP.
From days 14 to 28 after weaning, ADG and ADFI responded in a cubic (p < 0.05)
fashion as SP increased. Pigs fed 2 g SP kgÿ1 had the best ADG which was greater than
those fed the control diet or diet containing 5 g SP kgÿ1. Daily feed intake was greatest
for pigs fed either 2 or 20 g SP kgÿ1 compared with those fed 5 g SP kgÿ1, with those fed
the control diet having intermediate ADFI. Feed ef®ciency was not affected.
For the entire experimental period (days 0±28 after weaning), ADG tend to (cubic,
p < 0.08) and ADFI (cubic, p < 0.05) increased, decreased, and then increased again with
increasing SP (Table 3). Feed ef®ciency was unaffected by SP.
All diets were pelleted during the ®rst two weeks of the experiment. During the second
half of the experiment, days 14±28, pigs fed 2 g SP kgÿ1 had increased ADG compared
with those fed the control diet. The cubic response in growth and feed intake happened to
coincide with the feeding of meal-based diets. It was speculated that high temperatures
associated with the pelleting process may have damaged or inactivated the SP. Similar
heat stability problems have been observed in pig diets with supplemental enzymes or
probiotics that have been subjected to thermal processing (Gunther, 1986; Swanson and
Hancock, 1989; Maloney et al., 1998).
G.S. Grinstead et al. / Animal Feed Science and Technology 83 (2000) 237±247
243
Table 3
Effect of increasing Spirulina platensis on weanling pig performance (Experiment 1)a
Item
Spirulina plantensis (g kgÿ1)
SEM
0
2
5
20
Days 0±7
ADG (g)
ADFI (g)
F/G
127
144
1.14
113
139
1.22
122
145
1.18
140
151
1.07
Days 7±14
ADG (g)
ADFI (g)
F/G
223
239
1.07
238
264
1.10
214
246
1.14
Days 0±14
ADG (g)
ADFI (g)
F/G
175
192
1.09
176
201
1.14
Days 14±28
ADG (g)
ADFI (g)
F/G
288
460
1.60
Days 0±28
ADG (g)
ADFI (g)
F/G
231
326
1.40
Probability (P