- Email: [email protected]
Evaluation of a Method for Determination of True Metabolizable Energy of Feed Ingredients
Evaluation of a Method for Determination of True Metabolizable Energy of Feed Ingredients D. B. CHAMI, PRAN VOHRA, and F. H. KRATZER Department of Avian Sciences, University of California, Davis, California 95616 (Received for publication March 1,1979)
INTRODUCTION
MATERIALS AND METHODS
Sibbald (1976) suggested a relatively simple method for the bioassay of metabolizable energy (ME) using adult roosters. He uses a term "true metabolizable energy" (TME) for his determinations as he makes a correction for the endogenous excreta energy to differentiate it from non-corrected apparent metabolizable energy (AME) where TME = AME + Endogenous excreta energy. He force-fed a known amount of a pelleted ingredient and collected the excreta over a 24-hr period. Farrell (1978) has also developed a rapid method for AME determination in which he trained roosters to consume about 70 g food in 1 hr and collected the excreta over 24 and 48 hr. He diluted a basal diet consisting of maize, fish meal, and bone meal supplemented with the test ingredient to determine AME of the latter. He found considerable variation (from 7.77 to 19.6 kcal/day) in endogenous excreta energy which would greatly influence TME. Sibbald (1978) also found the values to vary from 5.9 to 10.6 kcal/day. We have further studied the method of AME and TME determinations, and used roosters trained to eat their food in 1 hr rather than force-feeding them. The effect of some toxicants which reduce AME (Vohra, 1972) has also been investigated on TME.
Nine-month-old Single Comb White Leghorn roosters of approximately the same weight were housed in individual cages with individual feeders made from milk cartons. The excreta were collected in aluminum-foil trays from individual birds which were trained to eat their daily food in 1 hr. The test materials were ground coarsely in a Wiley mill, and a known weight was offered to five to nine roosters starved for 24 hr. After 1 hr, the feeders were removed and the exact amount of test material consumption was determined. The excreta were collected over the 24-hr and in some instances over the 48-hr periods. The excreta were dried in a forced draft oven at 100 C and ground finely for gross energy determination. The endogenous energy of excreta was determined from the collection of birds between 24 to 48 hr after the start of fasting. The gross energy of finely ground test samples was also determined. From these data, AME and TME were calculated as follows:
569
AME(kcal/kg) = (Gross energy intake - Excreta energy) gram test ingredient intake X 1000
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
ABSTRACT True metabolizable energy (TME) values for brewer's dried grain, corn, milo, rice bran, soybean meal, stock mash, and water grass seed were determined for adult roosters using 24-hr and 48-hr periods for excreta collection. The values obtained by considering 24-hr excreta period were significantly higher than those from 48-hr excreta collection for brewer's grain, soybean meal, and water grass seed. TME values of corn and soybean meal were significantly reduced in the presence of 2% guar gum or 1% tannic acid, considering the excreta collection over 48-hr period. TME of soybean meal was reduced to the same extent by 1% tannic acid or .05% gossypol. The concept of TME utilizing either 24 or 48-hr periods for excreta collection for all feedstuffs is questionable. 1980 Poultry Science 59:569-571
570
CHAMI ET AL.
rtO_Qojrtrt_Q_Qrtrtrtrt
+1 +| +| +1 +| +| +1 +1 +1 +1 +! +1 H V O m f f t O H i f t O ^ H O v i ' Tj-OOsOv»tSO\0\NOrt(N
2
H i n \ O v N m H O ' t N m H O +1 +1 +1 +1 +1 +| +| +| +| +| +| +|
XI
>,
Oh»fovo*mi-H^l-^0*NiniHr4
o
00Q©OOym©©O©r«%ift rs •#• Tt* ^t* m mm m m m m m
c
[A
0 0 H H N O \ C O M 0 O W 0 0 C O N I
+1 +1 +1 -H -H +1 +1 +1 +1 +1 +1 +| O O ' t S O O ' O t ' A I - C O i r t C O
w S O
w
II
tl
N a « a w c c H i r t x 4 ; c o N t +1 +1 +1 +1 +1 +1 +1 +i +| +i +i +i C O n i - N O O w r r i T j - T t ' i n ' t
•2 "«
3 S
"5 it-
's
* " " i—I H N +1 +1 +1 +1 +1 +l +l + | + | + | +i + |
T—I
60 >> O
°a 5 <•>
rt c Q W
• 2 ^
rn
•+
X
*(N
r>
1
ts N rt H ^ M3 O J ON H » 00 Th i-I r-I rt " * ' ' H N H rf +1 +1 +1 +] +| +| +| +1 +1 +| +| +| oo q H i n M rt n> T|| v i q N o \ TH
w^-it-H
H c
?a 60 rt u
i-i T* T* tr-t i-i m
>N
S •«
Ml U C w J3 W u X
• *
rg
1 W o
( N r H H H H \ d f o N m ' m m ' \ 0 +i +i +i +i +i +i +i +i +i +i +l +i ^ m N N m \ O H N T | - 0 0 \ O O \ (SrnrHO\Tt:l>0<^^6vOI>o6
* £
ST w
r
m O f n O O t ^ ' O O O m t H r£-r!rm-r!rm\£c6a6*~i^6in*~':
<
^H^HTHT-HI-H
H
H
N
m
+i +i +i +i +i +i +i +i +i +i +i +i
N q c o o ^ N q ', o q ^ o q ^ o i n: h . O \ h . v d d f n t ^ \ o o \ t > i T l O H t s O O \ O f i a m \ O ^ M ^ i-iC-ii-ti-ti-li-tT-l-r-ir-t-r-ti-tm
^
-o ^
60 U t-< c
is 3 J3 60
meal (SB % guar gu % tannic ossypol (. ash ass seed
S E"2S
gua tan
C
c
+ +
S e e n " o o o° 8 fflUUU S'S C/3
Q rt
M C I*
oybe BM + BM + BM + tock ter
&:
C/3 V3 V} C/l
£
s-°: «
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
H
TME DETERMINATION The excreta energy was for a 24-hr or a 48hr period. To obtain TME from AME, endogenous extra energy was added over. 24-hr or over 48-hr periods in the expression: TME = AME + Endogenous excreta energy. The data on AME and TME were analyzed for statistical significance using either Student's " t " test or by analysis of covariance. The effect of toxicants such as guar gum and tannic acid on the AME and TME of corn and soybean meal was tested. Gossypol was tested with soybean meal only. RESULTS AND DISCUSSION
significantly reduced these values at 48 hr in comparison to the 24-hr values. Gossypol (.05%) reduced AME and TME of soybean meal to the same extent as tannic acid. As only five roosters were used in gossypol study, the data were subjected to " t " test only. From these studies it can be concluded that toxicants such as guar gum, tannic acid, and gossypol interfere with AME and TME determinations. The time interval of 24 hr for excreta correction may not be enough for elimination of all dietary indigestable material associated with some ingredients. Sibbald's method (1976) is fast, but not accurate for all feed ingredients. It is questionable to regard the TME method as scientifically more accurate than conventional AME methods. The method of Sibbald (1976) is no faster than the AME method of Farrell (1978). It may be more desirable to dilute a basal diet with the test ingredient and determine AME according to the procedure of Farrell (1978) because excreta collection over 24-, 48-, and 72-hours post-feeding gave the same AME values. However, we speculate that these values will be also influenced by toxicants. Further research is needed to elaborate on effect of toxicants on the AME method of Farrell (1978).
REFERENCES Farrell, D. J.. 1978. Rapid determination of metabolizable energy of foods using cockerels. Brit. Poultry Sci. 19:303-308. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feeding stuffs. Poultry Sci. 55:303 — 308. Sibbald, I. R., 1978. The metabolic and endogenous energy losses of adult roosters. Poultry Sci. 57:556-557. Vohra, P., 1972. Evaluation of metabolizable energy for poultry. World's Poultry Sci. J. 29:204-214.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
When feed ingredients such as brewers dried grain, corn, milo, rice bran, soybean meal, stock mash, or water grass seed were tested alone without mixing with stock mash, AME values over the 24-hr period were significantly higher than those over the 48-hr period (Table 1). However, TME values were not significantly different over these two excreta-collection periods for corn, milo, rice bran, or stock mash. TME values were significantly higher over the 24-hr than the 48-hr periods for brewer's dried grain, soybean meal, and water grass seed. The excreta energy over the 24- to 48 hr collection period did not reach the endogenous levels suggesting a transit time longer than 24 hr when these materials were fed. In the presence of 2% guar gum, the AME of corn and soybean meal were significantly lower for 48 hr than for 24 hr. TME of corn plus guar gum over these 2 intervals was about the same. However, guar gum significantly reduced the TME as well as AME of corn, but not the TME of soybean meal when excreta collection was made only over the 48 hr period. Tannic acid (1.0%) significantly reduced AME as well as TME when added to corn or soybean meal for 48 hr collections. It also
571
INTRODUCTION
MATERIALS AND METHODS
Sibbald (1976) suggested a relatively simple method for the bioassay of metabolizable energy (ME) using adult roosters. He uses a term "true metabolizable energy" (TME) for his determinations as he makes a correction for the endogenous excreta energy to differentiate it from non-corrected apparent metabolizable energy (AME) where TME = AME + Endogenous excreta energy. He force-fed a known amount of a pelleted ingredient and collected the excreta over a 24-hr period. Farrell (1978) has also developed a rapid method for AME determination in which he trained roosters to consume about 70 g food in 1 hr and collected the excreta over 24 and 48 hr. He diluted a basal diet consisting of maize, fish meal, and bone meal supplemented with the test ingredient to determine AME of the latter. He found considerable variation (from 7.77 to 19.6 kcal/day) in endogenous excreta energy which would greatly influence TME. Sibbald (1978) also found the values to vary from 5.9 to 10.6 kcal/day. We have further studied the method of AME and TME determinations, and used roosters trained to eat their food in 1 hr rather than force-feeding them. The effect of some toxicants which reduce AME (Vohra, 1972) has also been investigated on TME.
Nine-month-old Single Comb White Leghorn roosters of approximately the same weight were housed in individual cages with individual feeders made from milk cartons. The excreta were collected in aluminum-foil trays from individual birds which were trained to eat their daily food in 1 hr. The test materials were ground coarsely in a Wiley mill, and a known weight was offered to five to nine roosters starved for 24 hr. After 1 hr, the feeders were removed and the exact amount of test material consumption was determined. The excreta were collected over the 24-hr and in some instances over the 48-hr periods. The excreta were dried in a forced draft oven at 100 C and ground finely for gross energy determination. The endogenous energy of excreta was determined from the collection of birds between 24 to 48 hr after the start of fasting. The gross energy of finely ground test samples was also determined. From these data, AME and TME were calculated as follows:
569
AME(kcal/kg) = (Gross energy intake - Excreta energy) gram test ingredient intake X 1000
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
ABSTRACT True metabolizable energy (TME) values for brewer's dried grain, corn, milo, rice bran, soybean meal, stock mash, and water grass seed were determined for adult roosters using 24-hr and 48-hr periods for excreta collection. The values obtained by considering 24-hr excreta period were significantly higher than those from 48-hr excreta collection for brewer's grain, soybean meal, and water grass seed. TME values of corn and soybean meal were significantly reduced in the presence of 2% guar gum or 1% tannic acid, considering the excreta collection over 48-hr period. TME of soybean meal was reduced to the same extent by 1% tannic acid or .05% gossypol. The concept of TME utilizing either 24 or 48-hr periods for excreta collection for all feedstuffs is questionable. 1980 Poultry Science 59:569-571
570
CHAMI ET AL.
rtO_Qojrtrt_Q_Qrtrtrtrt
+1 +| +| +1 +| +| +1 +1 +1 +1 +! +1 H V O m f f t O H i f t O ^ H O v i ' Tj-OOsOv»tSO\0\NOrt(N
2
H i n \ O v N m H O ' t N m H O +1 +1 +1 +1 +1 +| +| +| +| +| +| +|
XI
>,
Oh»fovo*mi-H^l-^0*NiniHr4
o
00Q©OOym©©O©r«%ift rs •#• Tt* ^t* m mm m m m m m
c
[A
0 0 H H N O \ C O M 0 O W 0 0 C O N I
+1 +1 +1 -H -H +1 +1 +1 +1 +1 +1 +| O O ' t S O O ' O t ' A I - C O i r t C O
w S O
w
II
tl
N a « a w c c H i r t x 4 ; c o N t +1 +1 +1 +1 +1 +1 +1 +i +| +i +i +i C O n i - N O O w r r i T j - T t ' i n ' t
•2 "«
3 S
"5 it-
's
* " " i—I H N +1 +1 +1 +1 +1 +l +l + | + | + | +i + |
T—I
60 >> O
°a 5 <•>
rt c Q W
• 2 ^
rn
•+
X
*(N
r>
1
ts N rt H ^ M3 O J ON H » 00 Th i-I r-I rt " * ' ' H N H rf +1 +1 +1 +] +| +| +| +1 +1 +| +| +| oo q H i n M rt n> T|| v i q N o \ TH
w^-it-H
H c
?a 60 rt u
i-i T* T* tr-t i-i m
>N
S •«
Ml U C w J3 W u X
• *
rg
1 W o
( N r H H H H \ d f o N m ' m m ' \ 0 +i +i +i +i +i +i +i +i +i +i +l +i ^ m N N m \ O H N T | - 0 0 \ O O \ (SrnrHO\Tt:l>0<^^6vOI>o6
* £
ST w
r
m O f n O O t ^ ' O O O m t H r£-r!rm-r!rm\£c6a6*~i^6in*~':
<
^H^HTHT-HI-H
H
H
N
m
+i +i +i +i +i +i +i +i +i +i +i +i
N q c o o ^ N q ', o q ^ o q ^ o i n: h . O \ h . v d d f n t ^ \ o o \ t > i T l O H t s O O \ O f i a m \ O ^ M ^ i-iC-ii-ti-ti-li-tT-l-r-ir-t-r-ti-tm
^
-o ^
60 U t-< c
is 3 J3 60
meal (SB % guar gu % tannic ossypol (. ash ass seed
S E"2S
gua tan
C
c
+ +
S e e n " o o o° 8 fflUUU S'S C/3
Q rt
M C I*
oybe BM + BM + BM + tock ter
&:
C/3 V3 V} C/l
£
s-°: «
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
H
TME DETERMINATION The excreta energy was for a 24-hr or a 48hr period. To obtain TME from AME, endogenous extra energy was added over. 24-hr or over 48-hr periods in the expression: TME = AME + Endogenous excreta energy. The data on AME and TME were analyzed for statistical significance using either Student's " t " test or by analysis of covariance. The effect of toxicants such as guar gum and tannic acid on the AME and TME of corn and soybean meal was tested. Gossypol was tested with soybean meal only. RESULTS AND DISCUSSION
significantly reduced these values at 48 hr in comparison to the 24-hr values. Gossypol (.05%) reduced AME and TME of soybean meal to the same extent as tannic acid. As only five roosters were used in gossypol study, the data were subjected to " t " test only. From these studies it can be concluded that toxicants such as guar gum, tannic acid, and gossypol interfere with AME and TME determinations. The time interval of 24 hr for excreta correction may not be enough for elimination of all dietary indigestable material associated with some ingredients. Sibbald's method (1976) is fast, but not accurate for all feed ingredients. It is questionable to regard the TME method as scientifically more accurate than conventional AME methods. The method of Sibbald (1976) is no faster than the AME method of Farrell (1978). It may be more desirable to dilute a basal diet with the test ingredient and determine AME according to the procedure of Farrell (1978) because excreta collection over 24-, 48-, and 72-hours post-feeding gave the same AME values. However, we speculate that these values will be also influenced by toxicants. Further research is needed to elaborate on effect of toxicants on the AME method of Farrell (1978).
REFERENCES Farrell, D. J.. 1978. Rapid determination of metabolizable energy of foods using cockerels. Brit. Poultry Sci. 19:303-308. Sibbald, I. R., 1976. A bioassay for true metabolizable energy in feeding stuffs. Poultry Sci. 55:303 — 308. Sibbald, I. R., 1978. The metabolic and endogenous energy losses of adult roosters. Poultry Sci. 57:556-557. Vohra, P., 1972. Evaluation of metabolizable energy for poultry. World's Poultry Sci. J. 29:204-214.
Downloaded from http://ps.oxfordjournals.org/ at NERL on May 24, 2015
When feed ingredients such as brewers dried grain, corn, milo, rice bran, soybean meal, stock mash, or water grass seed were tested alone without mixing with stock mash, AME values over the 24-hr period were significantly higher than those over the 48-hr period (Table 1). However, TME values were not significantly different over these two excreta-collection periods for corn, milo, rice bran, or stock mash. TME values were significantly higher over the 24-hr than the 48-hr periods for brewer's dried grain, soybean meal, and water grass seed. The excreta energy over the 24- to 48 hr collection period did not reach the endogenous levels suggesting a transit time longer than 24 hr when these materials were fed. In the presence of 2% guar gum, the AME of corn and soybean meal were significantly lower for 48 hr than for 24 hr. TME of corn plus guar gum over these 2 intervals was about the same. However, guar gum significantly reduced the TME as well as AME of corn, but not the TME of soybean meal when excreta collection was made only over the 48 hr period. Tannic acid (1.0%) significantly reduced AME as well as TME when added to corn or soybean meal for 48 hr collections. It also
571