Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol81.Issue3-4.Oct1999:
Animal Feed Science and Technology
81 (1999) 193±203
Effects of DL-methionine hydroxyanalogue (MHA)
or DL-methionine (DL-Met) on N-retention
in broiler chickens and pigs
Andrea RoÈmer, Hj. Abel*
Institut fuÈr Tierphysiologie und TierernaÈhrung, Kellnerweg 6, 37077 GoÈttingen, Germany
Received 3 July 1998; received in revised form 17 February 1999; accepted 23 June 1999
Abstract
Methionine hydroxyanalogue (MHA) was evaluated for metabolic equivalence compared to DLmethionine in practical diets for broiler chickens and pigs. Diets calculated to be deficient in
methionine, 2.1 and 1.9 g kgÿ1 in diets for chicks and pigs, respectively, were supplemented with
MHA1 or with molar equivalents of DL-methionine from suboptimal to optimal methionine feeding
level. A polynomial regression model was used to describe N-retention in response to the DLmethionine or DL-MHA supplemented diets. Both supplements showed equal effects on N-balances
of chickens and pigs. N-retention (as proportion of N-intake) was 0.56 and 0.54 in chickens and
0.51 and 0.54 in pigs for DL-Met and DL-MHA, respectively. # 1999 Elsevier Science B.V. All
rights reserved.
Keywords: Chickens; Pigs; N-balance trials; Methionine hydroxyanalogue utilization
1. Introduction
Methionine-deficient diets for broilers and pigs can be supplemented with DLmethionine or with DL-methionine hydroxyanalogue. Metabolic equivalence of these two
sources of methionine is considered controversial, discrepancies being attributed to their
absorptive and enzymatic characteristics in metabolism (Knight and Dibner, 1984; Knight
et al., 1997). The utilization of MHA may also be influenced by the experimental diet
used, i.e. synthetic or practical based feed mixtures (Saunderson, 1985) as well as by the
*
1
Corresponding author. Tel.: +551/393359; fax: +551/393343.
Alimet1 a registered trademark of Monsanto Inc.
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 8 6 - 3
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A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
ratio of mono- to di-, tri- and polymeric acids of the MHA-product (Boebel and Baker,
1982). Furthermore, it is possible that the amount of supplemented methionine mainly
within the suboptimal supplementation level could cause interferences with absorption
mechanisms (Brachet and Puigserver, 1987; Baker and Boebel, 1980) and therefore be
responsible for discrepancies between the results of several studies. Both, equivalent
(Garlich, 1985; Waldroup et al., 1981; Knight and Dibner, 1984; Chung and Baker, 1992
and Stockland et al., 1992) and lower growth rates and feed conversion efficiencies
(Schutte and De Jong, 1996; Boebel and Baker, 1982; Huyghebaert, 1993; Van Weerden
et al., 1992; Steinhart and Kirchgeûner, 1985) have been shown in broiler chickens and
pigs. However, comparisons between MHA or DL-Met for N-retentions in broilers and
pigs have not yet been conducted. The present investigation compares the effects of
increasing supplemental levels of either DL-Met or DL-MHA in methionine-deficient basal
diets on N-retention in broiler chickens and growing pigs.
2. Material and methods
2.1. Animals and diet
2.1.1. Experiment 1
Male broiler chickens were obtained from a commercial hatchery (provenance
Lohmann) at one day of age and offered a commercial starter diet ad libitum. At 14 days
of age, the chicks were assigned individually to metabolism cages. Two supplements, DLMet and MHA, each were fed at four increasing levels. At each supplemental level nine
birds were fed DL-Met, nine other birds MHA and a further six birds received the
unsupplemented basal diet. Each experimental period lasted for 10 days, including five
days of adjustment and five days of collection. The basal mixture consisted per kg air dry
matter of 510 g wheat, 400 g field beans (white flowered), 50 g soya bean meal, 10 g
vitamins and 30 g minerals. It was calculated to contain per kg DM: 2.3 g methionine;
3.9 g cystine; 11.0 g lysine±HCl; 7.4 g threonine, 16.3 g arginine and 12.2 MJ MEN-corr..
Increasing amounts of DL-Met or DL-MHA2 were supplemented in the experimental
groups. Four supplemental levels of each methionine source were tested on a molar
equivalent basis by adding 0.6, 1.2, 1.8 and 2.4 g DL-Met or DL-MHA-equivalents (termed
`Met 1±4' and `MHA 1±4' in the tables). Experimental diets were offered on an ad
libitum basis and individual feed consumption of the birds was determined daily. Within
the collection period, total amounts of excreta were collected daily. The excreta were
weighed and kept frozen (ÿ208C) until analysis.
2.1.2. Experiment 2
N-balance trials were conducted on 32 crossbred barrows (provenance HuÈlsenberg).
The trial period lasted for 10 days, including five days of adjustment and five days of
collection. The animals were housed individually in metabolism cages. A complete diet
for growing pigs was formulated according to the feeding standards (GfE, 1987)
2
DL-MHA
free acid, liquid with 120 g water per kg.
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A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
consisting per kg air dry matter of 397.2 g wheat, 200 g barley, 370 g field beans
(coloured flowered), 2.0 g lysine±HCl; 0.5 g threonine, 0.3 g tryptophane and 30 g
mineral±vitamin premix. It was calculated to contain per kg DM: 11.1 g lysine; 1.9 g
methionine; 6.5 g threonine; 2.3 g tryptophane; and 14.4 MJ ME. Three supplementation
levels of each methionine source were tested by adding 0.8; 1.2 and 1.6 g DL-Met or DLMHA-equivalents on a molar basis (termed `Met 1±3' and `MHA 1±3' in the tables). Four
pigs were fed the basal diet; at supplemental levels 1 and 2, five pigs received the diet
with DL-Met or with MHA, respectively, at supplemental level 3 four pigs were fed the
DL-Met and four others the MHA diet. Equal amounts of feed adjusted to metabolic body
weight (kg0.75) were given twice daily. No feed refusals were encountered. Total amounts
of faeces and urine were collected separately and weighed daily. Aliquot samples were
taken and kept frozen (ÿ208C) until analysis.
2.2. Chemical analysis
Diets and excreta were analysed in duplicates for dry matter (DM), ash (CA), ether
extract (CL) and crude fiber (CF) according to standard Weende analysis methods
(Naumann et al., 1976). Nitrogen was determined by the Kjeldahl method. Crude protein
(CP; N*6.25) and N-free extracts (NfE) were calculated. Tables 1 and 2 show the
analysed nutrient contents of the broiler and pig diets. The contents of DL-Met and MHA
in diets were analysed by high performance liquid chromatography according to
Ontiveros et al. (1987). Results are shown in Tables 3 and 4 for broilers and pigs,
respectively.
Table 1
Analysed contents of dry matter (g DM) and of crude nutrients (g/kg DM) in diets with
supplementations for broilers
Group
DL-Met
or
DL-MHA
Parameter
DMa
CAb
CPc
CFd
CLe
NfEf
Basal diet
Met 1
MHA 1
902.4
910.9
899.7
42.7
43.3
43.0
216.1
216.1
217.4
54.8
55.1
55.0
29.5
28.6
29.0
656.9
656.9
655.6
Met 2
MHA 2
903.0
915.0
43.0
42.6
217.4
215.2
55.3
55.0
28.7
29.4
655.6
657.8
Met 3
MHA 3
887.9
918.8
42.5
43.3
219.6
210.8
54.6
55.2
29.9
28.5
653.4
662.2
Met 4
MHA 4
890.6
907.8
43.1
43.3
221.1
215.5
54.8
54.7
29.1
29.0
651.9
657.5
a
Dry matter.
Crude ash.
Crude protein.
d
Crude fibre.
e
Crude lipid.
f
N free extracts.
b
c
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A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 2
Analysed contents of dry matter (g DM) and of crude nutrients (g/kg DM) in diets with
supplementations for pigs
Group
DL-Met
or
DL-MHA
Parameter
DMa
CAb
CPc
CFd
CLe
NfEf
Basal diet
Met 1
MHA 1
871.6
873.3
873.6
54.9
56.6
56.1
192.6
192.2
192.8
57.2
55.9
57.0
22.5
22.1
23.8
672.8
673.2
670.3
Met 2
MHA 2
872.8
873.7
54.5
52.2
192.5
192.7
54.9
57.9
22.0
21.9
676.1
675.3
Met 3
MHA 3
873.2
872.9
56.4
56.1
192.5
192.5
60.9
59.6
23.0
22.7
667.2
669.1
a
Dry matter.
Crude ash.
c
Crude protein.
d
Crude fibre.
e
Crude lipid.
f
N free extracts.
b
Table 3
Analysed contents of
DL-Met
and MHA and of total methionine equivalents in diets for broilers (g/kg DM)
Group
No. of animals (n)
DL-MHA
DL-Met
Total
Basal diet
Met 1
MHA 1
24
9
9
±
±
0.71
2.28
2.92
2.29
2.28
2.92
3.00
Met 2
MHA 2
9
9
±
1.51
3.64
2.25
3.64
3.76
Met 3
MHA 3
9
9
±
2.44
4.34
2.24
4.34
4.68
Met 4
MHA 4
9
9
±
3.24
4.89
2.27
4.89
5.51
Table 4
Analysed contents of
DL-Met
and MHA and of total methionine equivalents in diets for pigs (g/kg DM)
Group
No. of animals (n)
DL-MHA
DL-Met
Total
Basal diet
Met 1
MHA 1
4
5
5
±
±
0.81
1.93
2.83
1.98
1.93
2.83
2.79
Met 2
MHA 2
5
5
±
1.17
3.11
1.81
3.11
2.98
Met 3
MHA 3
4
4
±
1.57
3.49
1.90
3.49
3.47
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
197
2.3. Statistical analysis
Data of N-balance trials were analysed by Student's t-test. The effect of DL-Met and
MHA intake on N-retentions in chickens and pigs was estimated using a polynomial
regression model with the equation:
Y a bx cx2
where Y = N-retention of chickens or pigs, a = intercept, which was set constant as a
common starting point, b and c = curvature steepness coefficients, x and x2 = amount of
total methionine intake with either DL-Met or DL-MHA supplementations.
For pigs the results of urine N-excretions were estimated separately using a hyperbola
(one site binding) regression model with the following equation:
Y Bmin X Kd X
where Y = average urine N-excretion of pigs, Bmin = minimum plateau value of Nexcretion, Kd = curvature steepness coefficient, X = amount of total methionine intake.
The regression analysis was performed with the program Graph Pad Prism (Vers. 10,
1980).
3. Results
3.1. Experiment 1
The initial and final body weights and weight gains of the broiler chickens are shown
in Table 5. The average daily body weight gain of broiler chickens was 44 g for the basal
Table 5
Body weight and weight gain of broiler chickens during N-balance trials (g, x, s)
Group
n
Initial body weight
Final body weight
Weight gain
x
s
x
s
x
s
Basal
Met 1
MHA 1
6
6
9
442
441
441
7
7
10
781
822
808
35
30
53
339
381
367
31
33
54
Basal
Met 2
MHA 2
6
9
9
414
413
412
14
17
14
770
877
883
67
49
49
356
464
471
63
45
41
Basal
Met 3
MHA 3
6
9
9
469
471
471
12
8
17
810
944
927
62
42
60
341
473
456
63
40
51
Basal
Met 4
MHA 4
6
9
9
453
451
450
29
25
29
804
924
903
57
65
49
351
473
453
40
46
31
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A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 6
Feed conversion ratio and N-balances in broiler chicks (x, s)
Group
Intake
ratio
(g/g)
(g N/animal/day)
Basal diet
1.83
0.12
2.97
0.43
1.64
0.30
1.33
0.18
0.45
0.039
Met 1
MHA 1
1.69
1.67
0.11
0.16
2.49
2.51
0.16
0.21
1.18
1.28
0.10
0.08
1.32
1.23
0.08
0.16
0.53
0.49
0.018
0.032
Met 2
MHA 2
1.50
1.55
0.07
0.09
3.20
3.28
0.19
0.27
1.40
1.47
0.09
0.14
1.80
1.80
0.13
0.15
0.56
0.55
0.018
0.018
Met 3
MHA 3
1.53
1.54
0.05
0.09
3.42
3.30
0.25
0.34
1.41
1.47
0.18
0.19
2.01
1.83
0.09
0.24
0.59
0.55
0.024
0.040
Met 4
MHA 4
1.57
1.56
0.06
0.04
3.42
3.21
0.39
0.22
1.54
1.41
0.24
0.13
1.88
1.80
0.19
0.17
0.55
0.56
0.029
0.031
x Met (1±4)
x MHA(1±4)
1.56
1.58
0.08
0.12
3.16
3.09
0.46
0.42
1.32
1.31
0.21
0.15
1.84
1.78
0.29
0.31
0.56
0.54
0.031
0.042
a
Excreta
Retentiona
Feed conversion
Retention
As proportion of N-intake.
diet and supplementation level 1 and 61 g for supplementation levels 2±4 with a standard
deviation of 5 g for both. Feed conversion ratio and results of N-balances are compiled in
Table 6.
Feed conversion ratio was significantly poorer in the basal diet group compared
to the supplemented groups. Within the supplemented groups, supplementation levels
2±4 showed better feed conversion ratios than supplementation level 1. Feed conversion ratios were not different between MHA and DL-Met groups. Furthermore,
N-retentions (as proportion of N-intake) were not different between the supplementation sources.
The regression analysis (Fig. 1(a)) showed no significant difference between the effects
of the two supplementation sources on N-retention.
3.2. Experiment 2
The initial and final body weights and weight gains of the pigs are shown in Table 7.
The average daily body weight gain was 575 g with a standard deviation of 103 g and
without any significant variation between groups. Results of the N-balance trials are
shown in Table 8.
N-retentions (as proportion of N-intake) showed no differences between the
supplementation sources. The highest N-excretions in urine were measured in the basal
diet group. Groups with MHA supplementations showed lower urine-N excretions
compared to DL-Met supplemented groups. N-retention was low in the basal diet group
and increased to similar levels in all supplemented groups. The results of regression
analysis (Fig. 1(b)) showed no significant differences between the supplementation
sources.
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
199
Fig. 1. Effects of increasing methionine supplementations on N-retentions of broiler chickens (a) and pigs (b)
(x, s).
4. Discussion
The aim of the study was to compare the effects of DL-Met and DL-MHA
supplementations on N-retentions in broiler chickens and growing pigs from suboptimal
to optimal methionine supplementation conditions. For that reason, methionine-deficient
basal diets based on high contents of field beans were formulated. Compared to the
official feeding standards the Met:ME(g/Mj), Met ratio in the basal diet was reduced by
42% with broilers (NRC, 1994) and by 40% with pigs (GfE, 1987).
200
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 7
Body weight and weight gain of pigs during N-balance trials (kg; x, s)
Group
Initial body weight
n
Final body weight
Weight gain
Basal
4
29.4
34.5
5.2
Met 1
MHA 1
5
5
29.4
29.4
35.4
35.5
6.1
6.1
Met 2
MHA 2
5
5
29.4
29.4
35.4
35.4
6.1
6.1
Met 3
MHA 3
4
4
29.3
29.4
35.4
35.5
6.1
6.1
Table 8
N-balances in pigs (x, s)
Group
Intake
Faeces
Urine
Retentiona
Retention
(g N/animal/day)
Basal diet
32.72
5.49
7.93
1.37
11.29
4.79
13.51
0.38
0.42
0.068
Met 1
MHA 1
34.41
32.87
3.17
1.75
8.22
7.94
1.22
0.98
9.07
6.73
2.58
1.82
17.12
18.20
2.45
0.97
0.50
0.55
0.073
0.028
Met 2
MHA 2
34.59
34.34
3.34
34.34
7.65
7.93
1.12
0.94
8.98
8.18
0.62
1.52
17.95
18.23
2.15
1.93
0.52
0.53
0.025
0.042
Met 3
MHA 3
34.08
33.93
2.65
3.37
7.85
8.28
1.02
1.44
8.54
7.09
0.34
0.95
17.69
18.56
1.91
1.60
0.52
0.55
0.025
0.010
xMet (1±3)
x MHA (1±3)
34.38
33.76
2.86
2.70
7.91
8.04
1.07
1.04
8.89ab 1.50
7.40bb 1.50
17.58
18.32
2.06
1.47
0.51
0.54
0.046
0.030
a
b
As proportion of N-intake.
Means within a column without common letters differ (p 0.05).
The basal diets were supplemented by adding molar equivalent doses of either DL-Met
or DL-MHA. MHA was assumed to be completely utilizable for the animals, irrespective
of composition concerning mono-, di- and polymer proportions. Results of feed analysis
(Tables 3 and 4) indicated good agreements of the calculated to the analysed methionine
contents for DL-Met. In diets for broilers the analysis of DL-MHA contents indicated
within supplementation levels 3 and 4 higher equivalent levels compared to DL-Met; diets
for pigs showed good agreements between DL-Met and DL-MHA contents.
Comparing the effects of DL-Met and DL-MHA results for chickens show similar weight
gains and feed conversions over the whole range from suboptimal to optimal supply for
both methionine sources, confirming observations of other researchers (Garlich, 1985;
Waldroup et al., 1981 and Knight and Dibner, 1984). Only few results concerning the
effects of DL-Met and DL-MHA supplementation on N-retention in broiler chickens have
been reported. Compared to DL-Met equal (Han et al., 1990) or lower N-balances
(Rostagno and Barbosa, 1995) were determined for MHA.
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
201
Fig. 2. Effects of increasing methionine supplementations on urine N-excretions in pigs (x, s).
A direct comparison of the two methionine sources on N-retentions can only be done,
if similar amounts of both supplements are consumed by the animals. Fig. 1(a) shows
N-retentions of broiler chickens on base of the actual DL-Met and DL-MHA intake.
N-retentions of DL-MHA groups showed higher standard deviations than DL-Met groups.
The estimation of the regression curves resulted in somewhat higher N-retentions for
DL-Met compared to MHA supplementations. However, the difference was not significant.
As in broiler chickens there were also no differences for the effects of the two
methionine sources on weight gain and feed conversion ratios in pigs. This result
confirms earlier studies (Walz and Pallauf, 1996; Chung and Baker, 1992; Reifsnyder
et al., 1984), reporting equal effects of DL-Met and DL-MHA on growth performance
in pigs.
In contrast to the results of chicks the calculated regression curve for N-retentions in
pigs showed somewhat higher efficiencies with DL-MHA than with DL-Met supplementations. However, again the difference between the two curves was not significant.
Regression curves for the effect of DL-Met and DL-MHA on urine N-excretions of pigs are
shown in Fig. 2. Compared to DL-Met supplementations urine N-excretions were
significantly lower with MHA supplementations, indicating the efficient utilization
of the hydroxy analogue in N-metabolism of pigs. Lower urine N-excretion may
also reduce the potential of ammonia nitrogen losses in pig husbandry (Kirchgeûner and
Roth, 1993).
5. Conclusion
In conclusion there was equal utilization of MHA and DL-Met for each supplementation
level in pigs. Moreover, results indicate similar utilization of both sources of methionine
in growing chickens. Supplementation of methionine-deficient diets for pigs with MHA
202
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
instead of DL-methionine may lower urine N-excretion of the animals thus reducing the
ammonia-N-emission potential of livestock.
Acknowledgements
We want to thank Dr. Barbara Rischkowsky for critical reading of the manuscript.
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Van Weerden, E.J., Schutte, J.B., Bertram, H.L., 1992. Utilization of the polymers of methionine hydroxy
analogue free acid (MHA-FA) in broiler chicks. Arch. GefluÈgelk. 56, 63±68.
Waldroup, P.W., Mabray, C.J., Blackman, J.R., Slagter, P.J., Short, R.J., Johnson, Z.B., 1981. Effectiveness of
the free acid of methionine hydroxy analogue as a methionine supplement in broiler diets. Poultr. Sci. 60,
438±443.
Walz, O.P., Pallauf, J., 1996. Wirkungsvergleich von DL-Methionin und Methionin-Hydroxyanalog in Rationen
mit Ackerbohnen und Erbsen bei Ferkeln und Mastschweinen. Agrobiol. Res. 108, 155±158.
81 (1999) 193±203
Effects of DL-methionine hydroxyanalogue (MHA)
or DL-methionine (DL-Met) on N-retention
in broiler chickens and pigs
Andrea RoÈmer, Hj. Abel*
Institut fuÈr Tierphysiologie und TierernaÈhrung, Kellnerweg 6, 37077 GoÈttingen, Germany
Received 3 July 1998; received in revised form 17 February 1999; accepted 23 June 1999
Abstract
Methionine hydroxyanalogue (MHA) was evaluated for metabolic equivalence compared to DLmethionine in practical diets for broiler chickens and pigs. Diets calculated to be deficient in
methionine, 2.1 and 1.9 g kgÿ1 in diets for chicks and pigs, respectively, were supplemented with
MHA1 or with molar equivalents of DL-methionine from suboptimal to optimal methionine feeding
level. A polynomial regression model was used to describe N-retention in response to the DLmethionine or DL-MHA supplemented diets. Both supplements showed equal effects on N-balances
of chickens and pigs. N-retention (as proportion of N-intake) was 0.56 and 0.54 in chickens and
0.51 and 0.54 in pigs for DL-Met and DL-MHA, respectively. # 1999 Elsevier Science B.V. All
rights reserved.
Keywords: Chickens; Pigs; N-balance trials; Methionine hydroxyanalogue utilization
1. Introduction
Methionine-deficient diets for broilers and pigs can be supplemented with DLmethionine or with DL-methionine hydroxyanalogue. Metabolic equivalence of these two
sources of methionine is considered controversial, discrepancies being attributed to their
absorptive and enzymatic characteristics in metabolism (Knight and Dibner, 1984; Knight
et al., 1997). The utilization of MHA may also be influenced by the experimental diet
used, i.e. synthetic or practical based feed mixtures (Saunderson, 1985) as well as by the
*
1
Corresponding author. Tel.: +551/393359; fax: +551/393343.
Alimet1 a registered trademark of Monsanto Inc.
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 8 6 - 3
194
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
ratio of mono- to di-, tri- and polymeric acids of the MHA-product (Boebel and Baker,
1982). Furthermore, it is possible that the amount of supplemented methionine mainly
within the suboptimal supplementation level could cause interferences with absorption
mechanisms (Brachet and Puigserver, 1987; Baker and Boebel, 1980) and therefore be
responsible for discrepancies between the results of several studies. Both, equivalent
(Garlich, 1985; Waldroup et al., 1981; Knight and Dibner, 1984; Chung and Baker, 1992
and Stockland et al., 1992) and lower growth rates and feed conversion efficiencies
(Schutte and De Jong, 1996; Boebel and Baker, 1982; Huyghebaert, 1993; Van Weerden
et al., 1992; Steinhart and Kirchgeûner, 1985) have been shown in broiler chickens and
pigs. However, comparisons between MHA or DL-Met for N-retentions in broilers and
pigs have not yet been conducted. The present investigation compares the effects of
increasing supplemental levels of either DL-Met or DL-MHA in methionine-deficient basal
diets on N-retention in broiler chickens and growing pigs.
2. Material and methods
2.1. Animals and diet
2.1.1. Experiment 1
Male broiler chickens were obtained from a commercial hatchery (provenance
Lohmann) at one day of age and offered a commercial starter diet ad libitum. At 14 days
of age, the chicks were assigned individually to metabolism cages. Two supplements, DLMet and MHA, each were fed at four increasing levels. At each supplemental level nine
birds were fed DL-Met, nine other birds MHA and a further six birds received the
unsupplemented basal diet. Each experimental period lasted for 10 days, including five
days of adjustment and five days of collection. The basal mixture consisted per kg air dry
matter of 510 g wheat, 400 g field beans (white flowered), 50 g soya bean meal, 10 g
vitamins and 30 g minerals. It was calculated to contain per kg DM: 2.3 g methionine;
3.9 g cystine; 11.0 g lysine±HCl; 7.4 g threonine, 16.3 g arginine and 12.2 MJ MEN-corr..
Increasing amounts of DL-Met or DL-MHA2 were supplemented in the experimental
groups. Four supplemental levels of each methionine source were tested on a molar
equivalent basis by adding 0.6, 1.2, 1.8 and 2.4 g DL-Met or DL-MHA-equivalents (termed
`Met 1±4' and `MHA 1±4' in the tables). Experimental diets were offered on an ad
libitum basis and individual feed consumption of the birds was determined daily. Within
the collection period, total amounts of excreta were collected daily. The excreta were
weighed and kept frozen (ÿ208C) until analysis.
2.1.2. Experiment 2
N-balance trials were conducted on 32 crossbred barrows (provenance HuÈlsenberg).
The trial period lasted for 10 days, including five days of adjustment and five days of
collection. The animals were housed individually in metabolism cages. A complete diet
for growing pigs was formulated according to the feeding standards (GfE, 1987)
2
DL-MHA
free acid, liquid with 120 g water per kg.
195
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
consisting per kg air dry matter of 397.2 g wheat, 200 g barley, 370 g field beans
(coloured flowered), 2.0 g lysine±HCl; 0.5 g threonine, 0.3 g tryptophane and 30 g
mineral±vitamin premix. It was calculated to contain per kg DM: 11.1 g lysine; 1.9 g
methionine; 6.5 g threonine; 2.3 g tryptophane; and 14.4 MJ ME. Three supplementation
levels of each methionine source were tested by adding 0.8; 1.2 and 1.6 g DL-Met or DLMHA-equivalents on a molar basis (termed `Met 1±3' and `MHA 1±3' in the tables). Four
pigs were fed the basal diet; at supplemental levels 1 and 2, five pigs received the diet
with DL-Met or with MHA, respectively, at supplemental level 3 four pigs were fed the
DL-Met and four others the MHA diet. Equal amounts of feed adjusted to metabolic body
weight (kg0.75) were given twice daily. No feed refusals were encountered. Total amounts
of faeces and urine were collected separately and weighed daily. Aliquot samples were
taken and kept frozen (ÿ208C) until analysis.
2.2. Chemical analysis
Diets and excreta were analysed in duplicates for dry matter (DM), ash (CA), ether
extract (CL) and crude fiber (CF) according to standard Weende analysis methods
(Naumann et al., 1976). Nitrogen was determined by the Kjeldahl method. Crude protein
(CP; N*6.25) and N-free extracts (NfE) were calculated. Tables 1 and 2 show the
analysed nutrient contents of the broiler and pig diets. The contents of DL-Met and MHA
in diets were analysed by high performance liquid chromatography according to
Ontiveros et al. (1987). Results are shown in Tables 3 and 4 for broilers and pigs,
respectively.
Table 1
Analysed contents of dry matter (g DM) and of crude nutrients (g/kg DM) in diets with
supplementations for broilers
Group
DL-Met
or
DL-MHA
Parameter
DMa
CAb
CPc
CFd
CLe
NfEf
Basal diet
Met 1
MHA 1
902.4
910.9
899.7
42.7
43.3
43.0
216.1
216.1
217.4
54.8
55.1
55.0
29.5
28.6
29.0
656.9
656.9
655.6
Met 2
MHA 2
903.0
915.0
43.0
42.6
217.4
215.2
55.3
55.0
28.7
29.4
655.6
657.8
Met 3
MHA 3
887.9
918.8
42.5
43.3
219.6
210.8
54.6
55.2
29.9
28.5
653.4
662.2
Met 4
MHA 4
890.6
907.8
43.1
43.3
221.1
215.5
54.8
54.7
29.1
29.0
651.9
657.5
a
Dry matter.
Crude ash.
Crude protein.
d
Crude fibre.
e
Crude lipid.
f
N free extracts.
b
c
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A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 2
Analysed contents of dry matter (g DM) and of crude nutrients (g/kg DM) in diets with
supplementations for pigs
Group
DL-Met
or
DL-MHA
Parameter
DMa
CAb
CPc
CFd
CLe
NfEf
Basal diet
Met 1
MHA 1
871.6
873.3
873.6
54.9
56.6
56.1
192.6
192.2
192.8
57.2
55.9
57.0
22.5
22.1
23.8
672.8
673.2
670.3
Met 2
MHA 2
872.8
873.7
54.5
52.2
192.5
192.7
54.9
57.9
22.0
21.9
676.1
675.3
Met 3
MHA 3
873.2
872.9
56.4
56.1
192.5
192.5
60.9
59.6
23.0
22.7
667.2
669.1
a
Dry matter.
Crude ash.
c
Crude protein.
d
Crude fibre.
e
Crude lipid.
f
N free extracts.
b
Table 3
Analysed contents of
DL-Met
and MHA and of total methionine equivalents in diets for broilers (g/kg DM)
Group
No. of animals (n)
DL-MHA
DL-Met
Total
Basal diet
Met 1
MHA 1
24
9
9
±
±
0.71
2.28
2.92
2.29
2.28
2.92
3.00
Met 2
MHA 2
9
9
±
1.51
3.64
2.25
3.64
3.76
Met 3
MHA 3
9
9
±
2.44
4.34
2.24
4.34
4.68
Met 4
MHA 4
9
9
±
3.24
4.89
2.27
4.89
5.51
Table 4
Analysed contents of
DL-Met
and MHA and of total methionine equivalents in diets for pigs (g/kg DM)
Group
No. of animals (n)
DL-MHA
DL-Met
Total
Basal diet
Met 1
MHA 1
4
5
5
±
±
0.81
1.93
2.83
1.98
1.93
2.83
2.79
Met 2
MHA 2
5
5
±
1.17
3.11
1.81
3.11
2.98
Met 3
MHA 3
4
4
±
1.57
3.49
1.90
3.49
3.47
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
197
2.3. Statistical analysis
Data of N-balance trials were analysed by Student's t-test. The effect of DL-Met and
MHA intake on N-retentions in chickens and pigs was estimated using a polynomial
regression model with the equation:
Y a bx cx2
where Y = N-retention of chickens or pigs, a = intercept, which was set constant as a
common starting point, b and c = curvature steepness coefficients, x and x2 = amount of
total methionine intake with either DL-Met or DL-MHA supplementations.
For pigs the results of urine N-excretions were estimated separately using a hyperbola
(one site binding) regression model with the following equation:
Y Bmin X Kd X
where Y = average urine N-excretion of pigs, Bmin = minimum plateau value of Nexcretion, Kd = curvature steepness coefficient, X = amount of total methionine intake.
The regression analysis was performed with the program Graph Pad Prism (Vers. 10,
1980).
3. Results
3.1. Experiment 1
The initial and final body weights and weight gains of the broiler chickens are shown
in Table 5. The average daily body weight gain of broiler chickens was 44 g for the basal
Table 5
Body weight and weight gain of broiler chickens during N-balance trials (g, x, s)
Group
n
Initial body weight
Final body weight
Weight gain
x
s
x
s
x
s
Basal
Met 1
MHA 1
6
6
9
442
441
441
7
7
10
781
822
808
35
30
53
339
381
367
31
33
54
Basal
Met 2
MHA 2
6
9
9
414
413
412
14
17
14
770
877
883
67
49
49
356
464
471
63
45
41
Basal
Met 3
MHA 3
6
9
9
469
471
471
12
8
17
810
944
927
62
42
60
341
473
456
63
40
51
Basal
Met 4
MHA 4
6
9
9
453
451
450
29
25
29
804
924
903
57
65
49
351
473
453
40
46
31
198
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 6
Feed conversion ratio and N-balances in broiler chicks (x, s)
Group
Intake
ratio
(g/g)
(g N/animal/day)
Basal diet
1.83
0.12
2.97
0.43
1.64
0.30
1.33
0.18
0.45
0.039
Met 1
MHA 1
1.69
1.67
0.11
0.16
2.49
2.51
0.16
0.21
1.18
1.28
0.10
0.08
1.32
1.23
0.08
0.16
0.53
0.49
0.018
0.032
Met 2
MHA 2
1.50
1.55
0.07
0.09
3.20
3.28
0.19
0.27
1.40
1.47
0.09
0.14
1.80
1.80
0.13
0.15
0.56
0.55
0.018
0.018
Met 3
MHA 3
1.53
1.54
0.05
0.09
3.42
3.30
0.25
0.34
1.41
1.47
0.18
0.19
2.01
1.83
0.09
0.24
0.59
0.55
0.024
0.040
Met 4
MHA 4
1.57
1.56
0.06
0.04
3.42
3.21
0.39
0.22
1.54
1.41
0.24
0.13
1.88
1.80
0.19
0.17
0.55
0.56
0.029
0.031
x Met (1±4)
x MHA(1±4)
1.56
1.58
0.08
0.12
3.16
3.09
0.46
0.42
1.32
1.31
0.21
0.15
1.84
1.78
0.29
0.31
0.56
0.54
0.031
0.042
a
Excreta
Retentiona
Feed conversion
Retention
As proportion of N-intake.
diet and supplementation level 1 and 61 g for supplementation levels 2±4 with a standard
deviation of 5 g for both. Feed conversion ratio and results of N-balances are compiled in
Table 6.
Feed conversion ratio was significantly poorer in the basal diet group compared
to the supplemented groups. Within the supplemented groups, supplementation levels
2±4 showed better feed conversion ratios than supplementation level 1. Feed conversion ratios were not different between MHA and DL-Met groups. Furthermore,
N-retentions (as proportion of N-intake) were not different between the supplementation sources.
The regression analysis (Fig. 1(a)) showed no significant difference between the effects
of the two supplementation sources on N-retention.
3.2. Experiment 2
The initial and final body weights and weight gains of the pigs are shown in Table 7.
The average daily body weight gain was 575 g with a standard deviation of 103 g and
without any significant variation between groups. Results of the N-balance trials are
shown in Table 8.
N-retentions (as proportion of N-intake) showed no differences between the
supplementation sources. The highest N-excretions in urine were measured in the basal
diet group. Groups with MHA supplementations showed lower urine-N excretions
compared to DL-Met supplemented groups. N-retention was low in the basal diet group
and increased to similar levels in all supplemented groups. The results of regression
analysis (Fig. 1(b)) showed no significant differences between the supplementation
sources.
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
199
Fig. 1. Effects of increasing methionine supplementations on N-retentions of broiler chickens (a) and pigs (b)
(x, s).
4. Discussion
The aim of the study was to compare the effects of DL-Met and DL-MHA
supplementations on N-retentions in broiler chickens and growing pigs from suboptimal
to optimal methionine supplementation conditions. For that reason, methionine-deficient
basal diets based on high contents of field beans were formulated. Compared to the
official feeding standards the Met:ME(g/Mj), Met ratio in the basal diet was reduced by
42% with broilers (NRC, 1994) and by 40% with pigs (GfE, 1987).
200
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
Table 7
Body weight and weight gain of pigs during N-balance trials (kg; x, s)
Group
Initial body weight
n
Final body weight
Weight gain
Basal
4
29.4
34.5
5.2
Met 1
MHA 1
5
5
29.4
29.4
35.4
35.5
6.1
6.1
Met 2
MHA 2
5
5
29.4
29.4
35.4
35.4
6.1
6.1
Met 3
MHA 3
4
4
29.3
29.4
35.4
35.5
6.1
6.1
Table 8
N-balances in pigs (x, s)
Group
Intake
Faeces
Urine
Retentiona
Retention
(g N/animal/day)
Basal diet
32.72
5.49
7.93
1.37
11.29
4.79
13.51
0.38
0.42
0.068
Met 1
MHA 1
34.41
32.87
3.17
1.75
8.22
7.94
1.22
0.98
9.07
6.73
2.58
1.82
17.12
18.20
2.45
0.97
0.50
0.55
0.073
0.028
Met 2
MHA 2
34.59
34.34
3.34
34.34
7.65
7.93
1.12
0.94
8.98
8.18
0.62
1.52
17.95
18.23
2.15
1.93
0.52
0.53
0.025
0.042
Met 3
MHA 3
34.08
33.93
2.65
3.37
7.85
8.28
1.02
1.44
8.54
7.09
0.34
0.95
17.69
18.56
1.91
1.60
0.52
0.55
0.025
0.010
xMet (1±3)
x MHA (1±3)
34.38
33.76
2.86
2.70
7.91
8.04
1.07
1.04
8.89ab 1.50
7.40bb 1.50
17.58
18.32
2.06
1.47
0.51
0.54
0.046
0.030
a
b
As proportion of N-intake.
Means within a column without common letters differ (p 0.05).
The basal diets were supplemented by adding molar equivalent doses of either DL-Met
or DL-MHA. MHA was assumed to be completely utilizable for the animals, irrespective
of composition concerning mono-, di- and polymer proportions. Results of feed analysis
(Tables 3 and 4) indicated good agreements of the calculated to the analysed methionine
contents for DL-Met. In diets for broilers the analysis of DL-MHA contents indicated
within supplementation levels 3 and 4 higher equivalent levels compared to DL-Met; diets
for pigs showed good agreements between DL-Met and DL-MHA contents.
Comparing the effects of DL-Met and DL-MHA results for chickens show similar weight
gains and feed conversions over the whole range from suboptimal to optimal supply for
both methionine sources, confirming observations of other researchers (Garlich, 1985;
Waldroup et al., 1981 and Knight and Dibner, 1984). Only few results concerning the
effects of DL-Met and DL-MHA supplementation on N-retention in broiler chickens have
been reported. Compared to DL-Met equal (Han et al., 1990) or lower N-balances
(Rostagno and Barbosa, 1995) were determined for MHA.
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
201
Fig. 2. Effects of increasing methionine supplementations on urine N-excretions in pigs (x, s).
A direct comparison of the two methionine sources on N-retentions can only be done,
if similar amounts of both supplements are consumed by the animals. Fig. 1(a) shows
N-retentions of broiler chickens on base of the actual DL-Met and DL-MHA intake.
N-retentions of DL-MHA groups showed higher standard deviations than DL-Met groups.
The estimation of the regression curves resulted in somewhat higher N-retentions for
DL-Met compared to MHA supplementations. However, the difference was not significant.
As in broiler chickens there were also no differences for the effects of the two
methionine sources on weight gain and feed conversion ratios in pigs. This result
confirms earlier studies (Walz and Pallauf, 1996; Chung and Baker, 1992; Reifsnyder
et al., 1984), reporting equal effects of DL-Met and DL-MHA on growth performance
in pigs.
In contrast to the results of chicks the calculated regression curve for N-retentions in
pigs showed somewhat higher efficiencies with DL-MHA than with DL-Met supplementations. However, again the difference between the two curves was not significant.
Regression curves for the effect of DL-Met and DL-MHA on urine N-excretions of pigs are
shown in Fig. 2. Compared to DL-Met supplementations urine N-excretions were
significantly lower with MHA supplementations, indicating the efficient utilization
of the hydroxy analogue in N-metabolism of pigs. Lower urine N-excretion may
also reduce the potential of ammonia nitrogen losses in pig husbandry (Kirchgeûner and
Roth, 1993).
5. Conclusion
In conclusion there was equal utilization of MHA and DL-Met for each supplementation
level in pigs. Moreover, results indicate similar utilization of both sources of methionine
in growing chickens. Supplementation of methionine-deficient diets for pigs with MHA
202
A. RoÈmer, Hj. Abel / Animal Feed Science and Technology 81 (1999) 193±203
instead of DL-methionine may lower urine N-excretion of the animals thus reducing the
ammonia-N-emission potential of livestock.
Acknowledgements
We want to thank Dr. Barbara Rischkowsky for critical reading of the manuscript.
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