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Effect of Protein Supplements Containing Urea or Natural Protein on Concentration of Trimethylamine in Cow's Milk1
E f f e c t o f P r o t e i n S u p p l e m e n t s C o n t a i n i n g Urea or N a t u r a l Protein on Concentration of Trimethylamine
in C o w ' s M i l k 1 R. S. MEHTA, R. BASSETTE, and E. E. BARTLEY Department of Animal Scienceand Industry Kansas Agricultural Experiment Station Manhattan 66506
ABSTRACT
INTRODUCTION
An attempt was made to reduce trimethylamine concentrations in milk by altering the protein supplement of the cow's rations. A gas chromatographic technique was used to analyze milk for trimethylamine. All cows were fed ad libitum a 1:1 mixture of alfalfa and prairie hay. Cows on the control ration also received a concentrate containing 43.5% sorghum grain, 43.5% corn, 10% wheat bran, and a 2.5% mineral-vitamin supplement. The protein equivalent was increased from 11% for the control ration to 17% for the other experimental rations by supplementing the ration with urea, Starea, or soybean meal. Each of three pairs of cows was fed one of the experimental rations, which was alternated with the control ration. For the fourth pair, the Starea ration was alternated with the urea ration. The urea ration reduced milk trimethylamine by 22%. Soybean meal supplementation did n o t appreciably affect trimethylamine in milk. Urea seemed slightly more effective than Starea in reducing concentrations of trimethylamine. To decrease trimethylamine in milk, it is recommended that urea or Starea be used as the supplementary source of protein in a cow's ration. Milk-flavor scores and trimethylamine concentrations were not related, probably because trimethylamine concentrations were well below threshold.
Work in our laboratory (3), as well as work elsewhere (2), established that cows fed wheat pasture produced fishly-flavored milk containing trimethylamine (TMA) concentrations above flavor thresholds. Wheat pasture would be used more widely in Kansas and some other Midwestern states if it did not cause off-flavors in milk. We have examined methods of eliminating TMA. Work in our laboratory (4) and elsewhere (2) has established that the concentration of TMA in milk from cows pastured on wheat is inconsistent. In all previous studies cows were fed concentrates while on wheat pasture. Suspecting that the concentration of TMA in milk is affected also by the concentrate portion of the cow's ration, we studied concentrations of TMA in milk from cows fed different types of proteins or protein supplements.
MATERIALS AND METHODS
Received September 14, 1977. 1Contribution No. 78-42-j, Department of Animal Sciences and Industry, Kansas Agricultural Experiment Station, Manhattan 66506. ~Starea (registered trademark 860255), U. S. Patent No. 3642489, patent assigned to Kansas State University Research Foundation. 3U. S. Patent No. 3642489, patent assigned to Kansas State University Research Foundation. 1978 J Dairy Sci 61:176-179
During a 19-wk study, four pairs of cows were subjected to four treatments (experimental design in Table 1). Three pairs of cows were used to compare TMA concentrations in milk from each of the treatments of supplementary urea, Starea 2, or soybean meal (SBM) with a control ration that contained no supplementary protein. Each of three pairs of cows was fed one of the experimental rations which was alternated with the control ration. A fourth pair of cows was used to compare urea with Starea. Compositions of the concentrate mixtures are in Table 2. Starea is a protein supplement made by extrusion-cooking a mixture of grain and urea under specific conditions of moisture, heat, and pressure. 3 The control concentrate mixture (ca. 11% crude protein) contained sorghum grain, corn, and wheat bran. The experimental concentrate mixtures (ca. 17% crude protein) were similar to the control ration except for the added protein supplements. The cows were fed 15 kg of concentrate
176
TRIMETHYLAMINE IN COW'S MILK
177
TABLE 1. Experimental design -- sequence of feeding protein supplements in cows whose milk was tested for TMA. a Cow pair
Cow no.
1-2 b
3-7
Weeks 8-14
15-19
1
1 2
Control Ureac
Control Ureac
Ureac Control
Control Ureac
2
3 4
Control Starea c
Control Starea c
Starea c Control
Control Starea c
3
5 6
Control SBM
Control SBM
S BM Control
Control SBM
4
7 8
Ureac Starea c
Ureac Starea c
Starea c Ureac
Ureac Starea c
aFor details of the composition of the feeds, see Table 2. bThe initial 2 weeks was an adjustment period. Ccontained 6% soybean meal (Table 2).
m i x t u r e p e r h e a d p e r day and also a 1:1 m i x t u r e o f alfalfa a n d prairie hay. The r o u g h a g e was fed ad l i b i t u m , and t h e c o w s c o n s u m e d ca. 7 kg per h e a d per day. Milks w e r e evaluated o r g a n o l e p f i c a l l y b y f o u r e x p e r i e n c e d judges using t h e p r o c e d u r e o f t h e N a t i o n a l Collegiate S t u d e n t J u d g i n g c o n test. In a d d i t i o n t o flavor analysis, t h e milks were evaluated b y t h e K O H - p e l l e t t e s t o f Bassette (1). T h e pellet t e s t is an o r g a n o l e p t i c m e t h o d in w h i c h milk is m a d e alkaline a n d is smelled t o d e t e c t f e e d flavor. T h e gas c h r o m a t o g r a p h i c (GLC) m e t h o d f o r m e a s u r i n g T M A c o n c e n t r a t i o n s in milk was as d e s c r i b e d b y M e h t a et al. (3). F o r each s a m p l e
o f milk, distillations were duplicate, and t w o head-space-gas samples w e r e o b t a i n e d per distillation t o be i n j e c t e d i n t o t h e GLC.
RESULTS A N D DISCUSSION
T M A c o n c e n t r a t i o n s in milk were a f f e c t e d b y t r e a t m e n t . N o r e l a t i o n s h i p was observed b e t w e e n t h e p e a k heights o f o t h e r basic volatile materials a n d t r e a t m e n t s . A f o u r - m e m b e r taste panel f o u n d n o d i r e c t r e l a t i o n s h i p b e t w e e n t h e s e t r e a t m e n t s and flavor scores or scores o f K O H pellet test. C o n c e n t r a t i o n s o f T M A were b e l o w t h e 2 - p p m t h r e s h o l d (3), so t h a t it was n o t surprising t h a t t h e y c o u l d n o t be d e t e c t e d
TABLE 2. Composition of concentrate mixtures.
Ingredients
Crude protein a
Protein supplements Control
Urea
97.0
89.5 6.0
Starea
SBM
85.0 6.0 6.0
81.0 16.0
(%) Sorghum, corn, and gran Soybean meal (SBM) Starea Urea Vitamin-mineral mix b % Crude protein in ration
11 49 73 281
3.0
1.5 3.0
3.0
3.0
10.7
17.0
16.7
16.8
aDry-matter basis. bvitamins A and D, dicalcium phosphate, and trace minerals. Journal of Dairy Science Vol. 61, No. 2, 1978
178
MEHTA ET AL.
organoleptically. Figure 1 compares TMA and flavor scores of milk from cows fed control and supplementary urea rations alternately. The flavor scores and TMA concentrations were not related, probably because TMA concentrations were well below threshold. Urea depressed TMA concentration. Average TMA concentrations for each of the three periods (histograms, Fig. 1) revealed that urea reduced the TMA concentration in milk by an average of 43% for cow 1 and 38% for cow 2. Starea (Fig. 2) also reduced concentration of TMA in milk, though not as much as urea did. Although the Starea concentrate mixture contained the same quantity of urea as the urea mixture, it is understandable that TMA concentrations might differ because Starea is metabolized in the rumen differently from the ways grain and urea are (5). Flavor scores were not affected by these treatments. Starea reduced TMA by 24% for cow 3 and by 20% for cow 4
CONTmOL~
x: j ~12
mN~
COW URtA
i :
I ~CON TROL~
~
~
ie TMA CONC ',m FLAVOR SCORE!
:
0
~ UIIEA
--
:
;
C0W 2 CONTROL
URtA
CONTIOL~
COW 5 StAREA
i
Id--
~CONTROt~
~12
!
~
a
'
!
!
!
>
t~a
T
:
;
;
0/ 2 '
~9
==
,
i 7
,
,
2
3 TRIAL
1 PERIOD
_
3
F I G . 1. C h a n g e s in t r i m e t h y l a m i n e c o n c e n t r a t i o n s a n d f l a v o r s c o r e s o f t w o c o w s on c o n t r o l a n d u r e a r a t i o n s (C = c o n t r o l , U = u r e a ) .
J o u r n a l o f Dairy S c i e n c e Vol. 6 1 , No. 2, 1 9 7 8
~ STARIA /
;
i , i ', , i 14 19 2 7 WEEKS ON T R I A L
~_
I
COW CONTROl
~ STAmIA
ie THA CONC, i . FLAVOR SCOREI
,,
:
14 19 2 ' 7 WEEKS ON T R I A L
(histograms, Fig. 2). The SBM had little effect on TMA concentrations, and there was little difference between the treatment and the control (Fig. 3). Supplementing the ration of cow 7 with urea more effectively reduced TMA in milk than supplementing it with Starea (Fig. 4). The pattern of TMA concentrations in milk was erratic when these supplements were fed to cow 8. The last sample from cow 8 was lost which further complicated analysis of the data. Additional research is necessary to clarify the relative merits of the two rations in reducing TMA in milk. The source of protein influenced TMA in cow's milk. Supplementing the control ration with either urea or Starea appreciably reduced TMA. It was not possible to establish a difference between Starea and urea for reducing TMA. High TMA in milk from cows on certain rations can be reduced to acceptable concentrations with urea or Starea.
; 14
19
40
!
o
2 TRIAL
1 PERIOD
m
2
F I G . 2. C h a n g e s in t r i m e t h y l a m i n e c o n c e n t r a t i o n s and flavor scores of t w o cows on control and Starea r a t i o n s (C = c o n t r o l , S = S t a r e a ) .
179
TRIMETHYLAM1NE IN COW'S MILK COW CONTtOLI
SOy
S
COW ~CONTROL ~
]
SOy
6
COW
CO N T I O L
SOy
""'"
CONe. !m F L A V O R SCOREI
',e T M A
1.2
1.2
7
COW
i,, .....
:: u,,,,,
i
i
,,
i e T M A CONC. i !m F L A V O R SCOREI
....
,., : .,,,.,
E
z_ 3o
30
Z a.
uJ o
.g
m
d
3s
>
v ur 14
19
WEEKS
19
)4
40 ,
ON T R I A L
12 17 WEEKS ON
,
i
,
i
7
,
12
17
TRIAL
i
SB
i
i
se
S
p•
C
S8
C
U
U
0
I
2
3
TRIAL
S S
U
1
PERIOD O
FIG. 3. Changes in trimethylamine concentrations and flavor scores of two cows on control and soybean meal rations (C = control, SB = soybean meal).
I
2
3 TRIAL
I PERIOD
2
3
FIG. 4. Changes in t r i m e t h y l a m i n e c o n c e n t r a t i o n s and f l a v o r s c o r e s o f t w o c o w s on urea and Starea r a t i o n s ( U = urea, S = S t a r e a ) .
REFERENCES
1 2
3
Bassette, R. 1965. Off-odor detection made easy. Amer. Dairy Rev. 27:82. Johnson, P. E., L. J. Bush, G. V. Odell, and E. L. Smith. 1973. Page 274 in The undesirable flavor in milk resulting f r o m grazing cows on wheat pasture. Oklahoma Agr. Exp. Sta. Misc. Publ. 90. Mehta, R. S., R. Bassette, and G. Ward. 1974. Trimethylamine responsible for fishy flavor in milk f r o m cows on wheat pasture. J. Dairy Sci. 57:285.
4
Mehta, R. S., R. Bassette, and G. Ward. 1977. Flavor of milk from cows on wheat pasture. (Unpublished data.) 5 Stiles, D. A., E. E. Bartley, R. M. Meyer, C. W. Deyoe, and H. B. Pfost. 1970. Feed Processing. VII. Effect of an expansion-processed mixture of grain and urea (Starea) on rumen metabolism in cattle and on urea toxicity. J. Dairy Sci. 53:1436.
Journal of Dairy Science Vol. 61, No. 2, 1978
in C o w ' s M i l k 1 R. S. MEHTA, R. BASSETTE, and E. E. BARTLEY Department of Animal Scienceand Industry Kansas Agricultural Experiment Station Manhattan 66506
ABSTRACT
INTRODUCTION
An attempt was made to reduce trimethylamine concentrations in milk by altering the protein supplement of the cow's rations. A gas chromatographic technique was used to analyze milk for trimethylamine. All cows were fed ad libitum a 1:1 mixture of alfalfa and prairie hay. Cows on the control ration also received a concentrate containing 43.5% sorghum grain, 43.5% corn, 10% wheat bran, and a 2.5% mineral-vitamin supplement. The protein equivalent was increased from 11% for the control ration to 17% for the other experimental rations by supplementing the ration with urea, Starea, or soybean meal. Each of three pairs of cows was fed one of the experimental rations, which was alternated with the control ration. For the fourth pair, the Starea ration was alternated with the urea ration. The urea ration reduced milk trimethylamine by 22%. Soybean meal supplementation did n o t appreciably affect trimethylamine in milk. Urea seemed slightly more effective than Starea in reducing concentrations of trimethylamine. To decrease trimethylamine in milk, it is recommended that urea or Starea be used as the supplementary source of protein in a cow's ration. Milk-flavor scores and trimethylamine concentrations were not related, probably because trimethylamine concentrations were well below threshold.
Work in our laboratory (3), as well as work elsewhere (2), established that cows fed wheat pasture produced fishly-flavored milk containing trimethylamine (TMA) concentrations above flavor thresholds. Wheat pasture would be used more widely in Kansas and some other Midwestern states if it did not cause off-flavors in milk. We have examined methods of eliminating TMA. Work in our laboratory (4) and elsewhere (2) has established that the concentration of TMA in milk from cows pastured on wheat is inconsistent. In all previous studies cows were fed concentrates while on wheat pasture. Suspecting that the concentration of TMA in milk is affected also by the concentrate portion of the cow's ration, we studied concentrations of TMA in milk from cows fed different types of proteins or protein supplements.
MATERIALS AND METHODS
Received September 14, 1977. 1Contribution No. 78-42-j, Department of Animal Sciences and Industry, Kansas Agricultural Experiment Station, Manhattan 66506. ~Starea (registered trademark 860255), U. S. Patent No. 3642489, patent assigned to Kansas State University Research Foundation. 3U. S. Patent No. 3642489, patent assigned to Kansas State University Research Foundation. 1978 J Dairy Sci 61:176-179
During a 19-wk study, four pairs of cows were subjected to four treatments (experimental design in Table 1). Three pairs of cows were used to compare TMA concentrations in milk from each of the treatments of supplementary urea, Starea 2, or soybean meal (SBM) with a control ration that contained no supplementary protein. Each of three pairs of cows was fed one of the experimental rations which was alternated with the control ration. A fourth pair of cows was used to compare urea with Starea. Compositions of the concentrate mixtures are in Table 2. Starea is a protein supplement made by extrusion-cooking a mixture of grain and urea under specific conditions of moisture, heat, and pressure. 3 The control concentrate mixture (ca. 11% crude protein) contained sorghum grain, corn, and wheat bran. The experimental concentrate mixtures (ca. 17% crude protein) were similar to the control ration except for the added protein supplements. The cows were fed 15 kg of concentrate
176
TRIMETHYLAMINE IN COW'S MILK
177
TABLE 1. Experimental design -- sequence of feeding protein supplements in cows whose milk was tested for TMA. a Cow pair
Cow no.
1-2 b
3-7
Weeks 8-14
15-19
1
1 2
Control Ureac
Control Ureac
Ureac Control
Control Ureac
2
3 4
Control Starea c
Control Starea c
Starea c Control
Control Starea c
3
5 6
Control SBM
Control SBM
S BM Control
Control SBM
4
7 8
Ureac Starea c
Ureac Starea c
Starea c Ureac
Ureac Starea c
aFor details of the composition of the feeds, see Table 2. bThe initial 2 weeks was an adjustment period. Ccontained 6% soybean meal (Table 2).
m i x t u r e p e r h e a d p e r day and also a 1:1 m i x t u r e o f alfalfa a n d prairie hay. The r o u g h a g e was fed ad l i b i t u m , and t h e c o w s c o n s u m e d ca. 7 kg per h e a d per day. Milks w e r e evaluated o r g a n o l e p f i c a l l y b y f o u r e x p e r i e n c e d judges using t h e p r o c e d u r e o f t h e N a t i o n a l Collegiate S t u d e n t J u d g i n g c o n test. In a d d i t i o n t o flavor analysis, t h e milks were evaluated b y t h e K O H - p e l l e t t e s t o f Bassette (1). T h e pellet t e s t is an o r g a n o l e p t i c m e t h o d in w h i c h milk is m a d e alkaline a n d is smelled t o d e t e c t f e e d flavor. T h e gas c h r o m a t o g r a p h i c (GLC) m e t h o d f o r m e a s u r i n g T M A c o n c e n t r a t i o n s in milk was as d e s c r i b e d b y M e h t a et al. (3). F o r each s a m p l e
o f milk, distillations were duplicate, and t w o head-space-gas samples w e r e o b t a i n e d per distillation t o be i n j e c t e d i n t o t h e GLC.
RESULTS A N D DISCUSSION
T M A c o n c e n t r a t i o n s in milk were a f f e c t e d b y t r e a t m e n t . N o r e l a t i o n s h i p was observed b e t w e e n t h e p e a k heights o f o t h e r basic volatile materials a n d t r e a t m e n t s . A f o u r - m e m b e r taste panel f o u n d n o d i r e c t r e l a t i o n s h i p b e t w e e n t h e s e t r e a t m e n t s and flavor scores or scores o f K O H pellet test. C o n c e n t r a t i o n s o f T M A were b e l o w t h e 2 - p p m t h r e s h o l d (3), so t h a t it was n o t surprising t h a t t h e y c o u l d n o t be d e t e c t e d
TABLE 2. Composition of concentrate mixtures.
Ingredients
Crude protein a
Protein supplements Control
Urea
97.0
89.5 6.0
Starea
SBM
85.0 6.0 6.0
81.0 16.0
(%) Sorghum, corn, and gran Soybean meal (SBM) Starea Urea Vitamin-mineral mix b % Crude protein in ration
11 49 73 281
3.0
1.5 3.0
3.0
3.0
10.7
17.0
16.7
16.8
aDry-matter basis. bvitamins A and D, dicalcium phosphate, and trace minerals. Journal of Dairy Science Vol. 61, No. 2, 1978
178
MEHTA ET AL.
organoleptically. Figure 1 compares TMA and flavor scores of milk from cows fed control and supplementary urea rations alternately. The flavor scores and TMA concentrations were not related, probably because TMA concentrations were well below threshold. Urea depressed TMA concentration. Average TMA concentrations for each of the three periods (histograms, Fig. 1) revealed that urea reduced the TMA concentration in milk by an average of 43% for cow 1 and 38% for cow 2. Starea (Fig. 2) also reduced concentration of TMA in milk, though not as much as urea did. Although the Starea concentrate mixture contained the same quantity of urea as the urea mixture, it is understandable that TMA concentrations might differ because Starea is metabolized in the rumen differently from the ways grain and urea are (5). Flavor scores were not affected by these treatments. Starea reduced TMA by 24% for cow 3 and by 20% for cow 4
CONTmOL~
x: j ~12
mN~
COW URtA
i :
I ~CON TROL~
~
~
ie TMA CONC ',m FLAVOR SCORE!
:
0
~ UIIEA
--
:
;
C0W 2 CONTROL
URtA
CONTIOL~
COW 5 StAREA
i
Id--
~CONTROt~
~12
!
~
a
'
!
!
!
>
t~a
T
:
;
;
0/ 2 '
~9
==
,
i 7
,
,
2
3 TRIAL
1 PERIOD
_
3
F I G . 1. C h a n g e s in t r i m e t h y l a m i n e c o n c e n t r a t i o n s a n d f l a v o r s c o r e s o f t w o c o w s on c o n t r o l a n d u r e a r a t i o n s (C = c o n t r o l , U = u r e a ) .
J o u r n a l o f Dairy S c i e n c e Vol. 6 1 , No. 2, 1 9 7 8
~ STARIA /
;
i , i ', , i 14 19 2 7 WEEKS ON T R I A L
~_
I
COW CONTROl
~ STAmIA
ie THA CONC, i . FLAVOR SCOREI
,,
:
14 19 2 ' 7 WEEKS ON T R I A L
(histograms, Fig. 2). The SBM had little effect on TMA concentrations, and there was little difference between the treatment and the control (Fig. 3). Supplementing the ration of cow 7 with urea more effectively reduced TMA in milk than supplementing it with Starea (Fig. 4). The pattern of TMA concentrations in milk was erratic when these supplements were fed to cow 8. The last sample from cow 8 was lost which further complicated analysis of the data. Additional research is necessary to clarify the relative merits of the two rations in reducing TMA in milk. The source of protein influenced TMA in cow's milk. Supplementing the control ration with either urea or Starea appreciably reduced TMA. It was not possible to establish a difference between Starea and urea for reducing TMA. High TMA in milk from cows on certain rations can be reduced to acceptable concentrations with urea or Starea.
; 14
19
40
!
o
2 TRIAL
1 PERIOD
m
2
F I G . 2. C h a n g e s in t r i m e t h y l a m i n e c o n c e n t r a t i o n s and flavor scores of t w o cows on control and Starea r a t i o n s (C = c o n t r o l , S = S t a r e a ) .
179
TRIMETHYLAM1NE IN COW'S MILK COW CONTtOLI
SOy
S
COW ~CONTROL ~
]
SOy
6
COW
CO N T I O L
SOy
""'"
CONe. !m F L A V O R SCOREI
',e T M A
1.2
1.2
7
COW
i,, .....
:: u,,,,,
i
i
,,
i e T M A CONC. i !m F L A V O R SCOREI
....
,., : .,,,.,
E
z_ 3o
30
Z a.
uJ o
.g
m
d
3s
>
v ur 14
19
WEEKS
19
)4
40 ,
ON T R I A L
12 17 WEEKS ON
,
i
,
i
7
,
12
17
TRIAL
i
SB
i
i
se
S
p•
C
S8
C
U
U
0
I
2
3
TRIAL
S S
U
1
PERIOD O
FIG. 3. Changes in trimethylamine concentrations and flavor scores of two cows on control and soybean meal rations (C = control, SB = soybean meal).
I
2
3 TRIAL
I PERIOD
2
3
FIG. 4. Changes in t r i m e t h y l a m i n e c o n c e n t r a t i o n s and f l a v o r s c o r e s o f t w o c o w s on urea and Starea r a t i o n s ( U = urea, S = S t a r e a ) .
REFERENCES
1 2
3
Bassette, R. 1965. Off-odor detection made easy. Amer. Dairy Rev. 27:82. Johnson, P. E., L. J. Bush, G. V. Odell, and E. L. Smith. 1973. Page 274 in The undesirable flavor in milk resulting f r o m grazing cows on wheat pasture. Oklahoma Agr. Exp. Sta. Misc. Publ. 90. Mehta, R. S., R. Bassette, and G. Ward. 1974. Trimethylamine responsible for fishy flavor in milk f r o m cows on wheat pasture. J. Dairy Sci. 57:285.
4
Mehta, R. S., R. Bassette, and G. Ward. 1977. Flavor of milk from cows on wheat pasture. (Unpublished data.) 5 Stiles, D. A., E. E. Bartley, R. M. Meyer, C. W. Deyoe, and H. B. Pfost. 1970. Feed Processing. VII. Effect of an expansion-processed mixture of grain and urea (Starea) on rumen metabolism in cattle and on urea toxicity. J. Dairy Sci. 53:1436.
Journal of Dairy Science Vol. 61, No. 2, 1978