114 A
.W. Jongbloed et al. Livestock Production Science 67 2000 113 –122
digestibility of
phytate-bound P
up to
40 synergistic interactive effect with phytase. On the
Jongbloed et al., 1996. This implies that 60 of the other hand, Radcliffe et al. 1998 showed an
phytate phosphorus is still unavailable. Jongbloed improved P digestibility by using 1.5 or 3.0 of
1987 reviewed that lowered intestinal pH increases citric acid, but no significant interaction was ob-
the solubility of P and phytate and improves P served between microbial phytase and citric acid.
absorption in the small intestine. In addition to their This lack of consistency in the conclusions implies a
effect on intestinal pH, supplementary organic acids need for further research.
can also bind various cations along the intestine and Therefore, the objective of this study was to
may act as chelating agents Ravindran and Kor- investigate the effects of microbial phytase, organic
negay, 1993, resulting in increased intestinal ab- acids at two doses, and their possible interactions on
sorption of minerals Table 1. However, there is a the apparent total tract digestibility of some nutrients
scarcity of experimental data on synergistic effects of and performance of grower pigs.
microbial phytase in the presence of various acids. The efficacy of microbial phytase is found to be
pH-dependent Simons et al., 1990. The highest activity was observed at two pH optima, i.e. 5.0 to
2. Materials and methods
5.5 and 2.5. Gastrointestinal acidity in pigs is not always favorable for efficient hydrolysis of phytates
2.1. Animals and housing by phytases. Most pig diets have a pH between 6.0
and 7.0, which can be lowered by supplementation of The experiment was carried out, using 192 grow-
organic acids, and may thus increase the efficacy of ing pigs [Finnish Landrace 3 Dutch Landrace] 3
microbial phytase. For example, Kemme et al. Cofok of about 22 kg initial BW. Each pen with six
1999 showed that supplementation of a grower- pigs three barrows 1 three gilts was the experimen-
finisher diet with 3 lactic acid not only had a tal unit. The pigs were housed for 5 weeks in
positive effect on the absorbability of P, but also a farrowing pens of 1.6 3 1.8 m at an average ambient
Table 1 Effect of various organic acids or their salts at different dietary levels on the improvement of the apparent total tract digestibility DC; in
-units of Ca, Mg and P in pigs Organic acid
Inclusion BW range
Improvement in DC Reference
kg Ca
Mg P
Ca-benzoate 2.4
60–65 1.4
20.2 24.4
Mroz et al. 1996 Ca-benzoate
2.4 40–100
9.0 0.0
0.3 Mroz et al. 1997
Butyric acid 2.7
40–100 4.4
20.4 3.4
Mroz et al. 1997 ¨
Citric acid 1.5
9–22 7.4
5.4 7.4
Hohler and Pallauf 1993 ¨
Citric acid 1.5
11–26 5.4
3.2 2.0
Hohler and Pallauf 1994 Citric acid
1.5 7–17
5.5 –
4.3 Radcliffe et al. 1998
Citric acid 3.0
7–17 4.8
– 3.7
Radcliffe et al. 1998 Citric acid
2.0 10–32
22.0 –
2.9 Radcliffe et al. 1998
Citric acid 1.5
7–21 21.0
– 1.0
Walz and Pallauf 1990, 1991 Fumaric acid
1.0 7
0.7 0.1
1.8 Kirchgessner and Roth 1980
Fumaric acid 2.0
7 6.2
0.7 5.2
Kirchgessner and Roth 1980 Fumaric acid
1.5 3.0 8
24.1 –
22.4 Radecki et al. 1988
Fumaric acid 1.5
7–21 0.5
– 2.3
Walz and Pallauf 1990, 1991 Fumaric acid
1.8 40–100
6.1 20.3
3.9 Mroz et al. 1997
Lactic acid 3.0
37–95 7.9
1.6 2.7
Kemme et al. 1999 Formic acid
1.4 40–100
1.3 21.8
4.6 Mroz et al. 1997
A .W. Jongbloed et al. Livestock Production Science 67 2000 113 –122
115
21
temperature of 208C, providing no bedding. The pens formic acid and 16 g kg
of lactic acid are usually were equipped with troughs and nipples for drinking
applied in practice. water. The animals were fed ad libitum, having free
access to water. 2.3. Formulation of the diets and feeding
The basal diet consisted of barley 30.0, ex- 2.2. Treatments and experimental design
tracted soybean meal 20.0, maize 17.25,
tapioca meal 10.0, extracted sunflower seed meal The dietary factors microbial phytase Natuphos ,
5.38, and extracted rapeseed meal 4.92 as its Gist-brocades, Delft, The Netherlands and organic
major components Table 2. Chromic oxide 0.25 acids lactic and formic acid, BASF, Ludwigshafen,
g kg was added as a marker according to the Germany were investigated according to a com-
procedure described
by Beers
and Jongbloed
pletely randomised block design. The animals in 1992b.
each of five blocks and pen had similar body weight Concentrations of crude protein CP; N 3 6.25,
and sex ratios. The pens within the blocks were Ca and total P were aimed at | 180, 6.0 and 4.2 g
allocated to the treatments at random and pen was
21
kg diet, respectively, on the basis of analysed
the experimental unit. The experiment comprised 10 contents in the major ingredients. Phytate-P ac-
treatments and there were four replicates per treat- counted for about 75 of total P. Microbial phytase
ment for the negative positive controls, and three
preparation Natuphos was added at 550 FTU replicates for each of the other treatments Table 2.
21
kg . Some characteristics of the basal diet not
Lactic acid or formic acid were used in doses of 0,
21
indicated in Table 2 were as follows: starch, 375 g 32 and 16, and 0, 16 and 8 g kg
diet, respectively
21 21
kg ; lysine, 10.3 g kg
; methionine 1 cystine, 6.5 in diets with or without microbial phytase 0 or 550
21 21
21
g kg and NE , 9.5 MJ kg
CVB, 1996. FTU kg
diet. The respective levels of 32 and 16 g
f 21
The organic acids were exchanged for equal kg
lactic acid are of the same acid equivalency as
21
amounts of maize starch. Lactic and formic acid 16 and 8 g kg
formic acid equal to 284 and 142
21 21
were supplied in a liquid form at the concentration of meq kg
, respectively. The doses of 8 g kg
Table 2
21
Formulation of the treatments g kg diet
Phytase 2
2 2
2 2
1 1
1 1
1 Acid
– LA
LA FA
FA –
LA LA
FA FA
21
Acid dose g kg –
32 16
16 8
– 32
16 16
8
a
Major ingredients 875.5
875.5 875.5
875.5 875.5
875.5 875.5
875.5 875.5
875.5
b
Minor ingredients 112.5
112.5 112.5
112. 5 112.5
112.5 112.5
112.5 112.5
112.5
c
Grower premix 1.0
1.0 1.0
1.0 1.0
1.0 1.0
1.0 1.0
1.0
d
Chrome starch mix 1.0
1.0 1.0
1.0 1.0
1.0 1.0
1.0 1.0
1.0 Maize starch
40.0 8.1
24.1 24.7
32.3 40.0
8.1 24.1
24.7 32.3
Lactic acid 80 –
31.9 15.9
– –
– 31.9
15.9 –
– Formic acid 85
– –
– 15.3
7.7 –
– –
15.3 7.7
21
Natuphos mg kg –
– –
– –
88 88
88 88
88
a
Barley 300, extracted soybean meal 200, maize 172.5, tapioca meal 100, extracted sunflower seed meal 53.8, extracted rapeseed meal 49.2.
b
Cane molasses 40.0, animal fat 26.7, limestone 10.7, salt 2.5,
L
-lysine.HCl 1.7,
L
-threonine 0.4,
DL
-methionine 0.2 and choline premix 0.3.
c 21
The grower premix provided mg kg diet: vitamin A: 8000 IU, vitamin D3: 2000 IU, vitamin E: 15 IU, vitamin K3: 1.5, vitamin B1:
1.0, vitamin B2: 4.0,
D
-pantothenic acid: 12, niacin: 20, vitamin B12: 0.020, folic acid: 0.2, vitamin B6: 1.0, Fe: 100, Cu: 25, Zn: 50, Mn: 30, Co: 0.15, I: 0.75, Se: 0.3.
d
The chromic oxide maize starch mixture was in a ratio of 1:3 w w.
116 A
.W. Jongbloed et al. Livestock Production Science 67 2000 113 –122
80 and 85, respectively. The basal diet was made Williams et al., 1962 in simple, whereas samples of
first without mineral premix, acids and microbial urine were analysed for pH, osmolarity, Ca, Mg and
phytase premix as one whole batch. Subsequently, all P. Organic acids were analysed by gas chromatog-
experimental treatments were prepared with the raphy. Phytic-P content was analysed according to
respective additives. All diets were cold pelleted Bos et al. 1993 and Cl, Cu, Zn, Na, K, in the
without steam; temperature not exceeding 508C to control diets only. Crude fat EG L 14 29-30
minimise possible inactivation of phytase and vol- Method B and crude fibre ISO DP 6865 NEN
atilisation of the acids. Subsequently, the feeds were 5415 were analysed only in the control diets and the
stored at 48C until use. diets with low acid dosage.
2.4. Collection procedure and measurements 2.6. Calculations and statistical analysis
Initial BW and final BW of each animal was Tabulated averages of phytase activity derive from
recorded and feed intake was registered per pen. assays in the samples taken directly after pelleting
Health status of the pigs was monitored permanently. and in the composite samples taken throughout the
Directly after pelleting the diets, a composite trial. Acid dose was taken as the amount of mmol of
sample of each treatment was taken and analysed for acid added to the diets. Performance was calculated
the content of N, Ca, P, and phytase activity to check as the average per pen over the total period of 5
whether the assumed values from linear program- weeks.
ming were realised. Experimental data were subjected to linear multi-
In the 4th and 5th week of the experiment ple regression analysis Genstat 5 release 3.1; Payne
composite samples of the diets were taken in dupli- et al., 1993. First, a best fit test was performed to
cate and analyzed on phytase activity and organic find out if the data regressed linearly and to check if
acids. In
parallel, subsamples
were air-dried.
the different acids had the same blank the controls. Besides, grab samples of faeces were collected for 2
This test showed that the lower and the higher dose consecutive days of the weeks 4 and 5 from each pen
of these acids gave the same response. Results of the according to Beers and Jongbloed 1992b and
two doses within an acid were therefore pooled. frozen at 2 208C. After the final collection period,
Firstly, we tested significance of differences between the faeces from each collection week were thawed,
digestibilities in weeks 4 and 5. Because there were homogenised, and subsamples were air-dried at 708C
no meaningful differences, we calculated the average before analysis. Samples of fresh urine were ob-
digestibility over weeks 4 and 5 per pen, and used tained from voluntarily urinating animals firstly into
this for the regression model. a glass beaker, measuring pH and osmolarity, and
The following model was used: then transferred directly into a cumulative bottle with
Y 5
m 1 block 1 phytase 1 acid 1 phytase 9 HCl to maintain pH below 3 until analysis.
ijk i
j k
3 acid 1 e , 1
jk ijk
2.5. Chemical analyses where Y
is an independent variable; m is the
ijk
Barley and all experimental diets were analysed overall mean; block is the block effect i 5 1.5;
i
for phytase activity before the trial started Engelen phytase is the phytase effect j 5 0, 1; acid is the
j k
et al., 1994. At that stage, the diets were also acid effect k 5 0, 1, 2; phytase3acid
is the
jk
analysed for DM, ash, Ca, Mg, P, and organic acids interaction effect; e
is the error distribution with
ijk 2
all analyses in fresh material. Individual main average 0 and variance
s . Due to different repli- ingredients and the composite samples of the diets
cates between treatments, the root mean square error were analysed for DM, ash, N, Ca, Mg, P, Na, K,
RMSE has been presented in the tables instead of AOAC, 1984 Cl, Cr, phytase activity, pH and
three standard error of differences of means S.E.D.. buffering capacity Prohaszka and Baron, 1980.
Differences among treatments were tested by t-test Faeces were analysed for DM, ash, Ca, Mg, P and Cr
and P-values are presented in the tables.
A .W. Jongbloed et al. Livestock Production Science 67 2000 113 –122
117
3. Results 3.2. Performance
