NITROGEN DYNAMICS IN THE RUMEN AND ABOMASUM OF SHEEP DETERMINED WITH 15 N-LABELLED AMMONIA OR 15 N-LABELLED DUCKWEED - Diponegoro University | Institutional Repository (UNDIP-IR)
NITROGEN DYNAMICS IN THE RUMEN AND ABOMASUM OF SHEEP
DETERMINED WITH 15N-LABELLED AMMONIA OR 15N-LABELLED DUCKWEED
Damry1 and J.V. Nolan2
Department of Animal Science, Tadulako University, Palu 94118
2
School of Environmental and Rural Science, UNE, Armidale, NSW 2351, Australia
E-mail: [email protected]
1
Received February 2, 2009; Accepted February 28, 2009
ABSTRACT
An experiment was carried out to investigate the dynamics of nitrogen (N) in the rumen and abomasum
of rumen and abomasum-cannulated sheep using 15N dilution techniques. The 15N tracer was administered
into the rumen as 15N-ammonia or 15N-labelled duckweed and the transfer of the 15N label to various N
pools was followed. Flow of digesta from the rumen into the abomasum was ascertained by double marker
technique with cobalt and acid insoluble ash as liquid digesta and particle digesta marker, respectively.
Results showed that the average of rumen water volume was 4.5 l ± SEM 0.57 and the mean water flow
through the abomasum (8.6 ± 0.45 l/d) was higher than outflow from the rumen (7.4 ± 0.55 l/d). Nitrogen
intake tended to be higher, but total-N passing the abomasum tended to be lower when the sheep were
infused by 15 N-ammonia than when they were ingesting 15N-duckweed. The ammonia concentration in
abomasal digesta was about 93 mg N/kg and non ammonia N (NAN) was about 1.58 g N/kg. The rates of
flow of total-N as ammonia-N and as NAN did not differ (P>0.05) between animals or diets, with means (±
SEM) of 57.7 ± 0.96 and 964 ± 2.13 mmol/d (or 0.81 and 13.5 g N/d), respectively. About 34-59% of the
dietary N was removed from the rumen as ammonia (absorbed and in digesta). The enrichments of rumen
ammonia N appeared to have reached plateau values after about 10 h of 15N-ammonia infusion. The percentage
of bacterial-N derived from ammonia-N (from the period of 15N-ammonia infusion) was 53.63 % (ratio of
plateau enrichments) and thus 37.47% of bacterial-N was derived from NAN sources in the rumen. The
total 15N flow through the abomasum was higher (P0.05
4.7
7.1
7.4
0.3
3.9
7.8
8.7
0.9
3.3
6.0
8.8
2.8
6.0
8.6
9.5
0.9
4.5
7.4
8.6
1.2
0.57
0.55
0.45
0.56
>0.05
>0.05
>0.05
>0.05
J.Indon.Trop.Anim.Agric. 34 [1] March 2009
Enrichments versus time in rumen fluid ammoniaN, NAN and bacterial-N, and ammonia-N and NAN
in abomasal digesta are presented for Sheep C and
D in Figures 1 and 2, respectively. The enrichments
of rumen ammonia N appeared to have reached
plateau values after about 10 h of 15 N-ammonia
infusion, although considerable variation in the
enrichments of ammonia was apparent. The
percentage of bacterial-N derived from ammonia-N
(from the period of 15N-ammonia infusion) was 53
63 % (ratio of plateau enrichments) and thus 37 47%
of bacterial-N was derived from NAN sources in
the rumen.
Figure 1 Enrichments (y axis; mol 15N/100 mol total ) versus time (x axis; h) in rumen fluid ammonia (○), rumen
fluid NAN (□) rumen bacterial-N (∆),abomasum ammonia (x) and abomasum NAN (◊) during a 72 h
administration of 2 µmol 15N/min as 15N-ammonia (top) or 15N-duckweed (bottom) for Sheep C
Figure 2 Enrichments (y axis; mol 15N/100 mol total ) versus time (x axis; h) in rumen fluid ammonia (○),
rumen fluid NAN (□) rumen bacterial-N (∆), reconstituted abomasum ammonia (x) and abomasum
NAN (◊) when 2 µmol 15N/min as 15 N-ammonia (top) or 15N-duckweed (bottom) was continually
supplied to the rumen (Sheep D).
Nitrogen Dynamics in the Rumen and Abomasum of Sheep (Damry and Nolan)
5
The total 15 N flow through the abomasum was
higher (P0.05
98.6
0.81
0.73
91.7
0.79
0.97
4.57
0.01
0.07
>0.05
>0.05
>0.05
0.50
0.81
10.4
0.50
0.81
9.98
0.02
>0.05
Values Determined when 15N-ammonia was Infused into The Rumen
Nitrogen Dynamics in the Rumen and Abomasum of Sheep (Damry and Nolan)
7
Table 1. Amounts of 15N Flowing in Various N Materials Through The Abomasum (mmol/d) During
a Continuous Provision into The Rumen of 15N-ammonia or 15N-Labelled Duckweed
15
15
N administered
N flow in abomasum NAN
15
N flow in bacterial-N
15
N flow in non-bacterial-N
15
N flow in abomasum ammonia-N
Total 15N flow through the abomasum
15
N absorbed from the rumen
15
15
N-ammonia
2.88
1.16
1.16
0.00
0.13
1.29
1.59
N-ammonia was infused into the rumen (not when
the tracer was provided by the 15N-duckweed as, in
this case, labelled NAN in the abomasum could be
non-bacterial in origin). The ratio, which was about
81 %, was assumed to apply throughout the
experiment and was also used in calculations for the
duckweed-ingesting animals. The ratio was higher
than that obtained for sheep with similar intakes of
DM by Siddons et al. (1982), and the estimates of
flow of bacterial-N through the abomasum (10.5 g
N/d), and the efficiency of bacterial-N synthesis (39
45 g N/kg DM apparently digested in the rumen, or
22 45 g N/kg DM truly digested in the rumen) also
seemed to lie at the high end of the range of published
values (SCA, 1990).
The proportion of duckweed-N that escaped
rumen fermentation was estimated from the data
describing the 15N balance across the rumen (Table
3). The 15N flowing through the abomasum would
have been present as both ammonia-N and NAN,
the latter consisting of microbial-N and non-microbialN. The non-microbial-N probably also contained
relatively small amounts of labelled endogenous
NAN. From the knowledge of bacterial-N enrichment
and the proportion of bacterial-N in the abomasal
NAN, the amount of 15 N in bacterial-N flowing
through the abomasum was calculated. Subtracting
the result from the total 15N flow gave an estimate of
the non-bacterial 15N-labelled NAN flow (0.85 mmol/
d). If the non-bacterial-N flow through the abomasum
is assumed to be solely from labelled escape
duckweed, then about 30 % of the duckweed N
ingested escaped digestion in the rumen which also
implies that about 70 % of the dietary duckweed-N
was degraded in the rumen. About 25 % of the 15N
8
15
N-duckweed
2.88
2.31
1.46
0.85
0.09
2.40
0.48
SEM
P
0.33
0.09
DETERMINED WITH 15N-LABELLED AMMONIA OR 15N-LABELLED DUCKWEED
Damry1 and J.V. Nolan2
Department of Animal Science, Tadulako University, Palu 94118
2
School of Environmental and Rural Science, UNE, Armidale, NSW 2351, Australia
E-mail: [email protected]
1
Received February 2, 2009; Accepted February 28, 2009
ABSTRACT
An experiment was carried out to investigate the dynamics of nitrogen (N) in the rumen and abomasum
of rumen and abomasum-cannulated sheep using 15N dilution techniques. The 15N tracer was administered
into the rumen as 15N-ammonia or 15N-labelled duckweed and the transfer of the 15N label to various N
pools was followed. Flow of digesta from the rumen into the abomasum was ascertained by double marker
technique with cobalt and acid insoluble ash as liquid digesta and particle digesta marker, respectively.
Results showed that the average of rumen water volume was 4.5 l ± SEM 0.57 and the mean water flow
through the abomasum (8.6 ± 0.45 l/d) was higher than outflow from the rumen (7.4 ± 0.55 l/d). Nitrogen
intake tended to be higher, but total-N passing the abomasum tended to be lower when the sheep were
infused by 15 N-ammonia than when they were ingesting 15N-duckweed. The ammonia concentration in
abomasal digesta was about 93 mg N/kg and non ammonia N (NAN) was about 1.58 g N/kg. The rates of
flow of total-N as ammonia-N and as NAN did not differ (P>0.05) between animals or diets, with means (±
SEM) of 57.7 ± 0.96 and 964 ± 2.13 mmol/d (or 0.81 and 13.5 g N/d), respectively. About 34-59% of the
dietary N was removed from the rumen as ammonia (absorbed and in digesta). The enrichments of rumen
ammonia N appeared to have reached plateau values after about 10 h of 15N-ammonia infusion. The percentage
of bacterial-N derived from ammonia-N (from the period of 15N-ammonia infusion) was 53.63 % (ratio of
plateau enrichments) and thus 37.47% of bacterial-N was derived from NAN sources in the rumen. The
total 15N flow through the abomasum was higher (P0.05
4.7
7.1
7.4
0.3
3.9
7.8
8.7
0.9
3.3
6.0
8.8
2.8
6.0
8.6
9.5
0.9
4.5
7.4
8.6
1.2
0.57
0.55
0.45
0.56
>0.05
>0.05
>0.05
>0.05
J.Indon.Trop.Anim.Agric. 34 [1] March 2009
Enrichments versus time in rumen fluid ammoniaN, NAN and bacterial-N, and ammonia-N and NAN
in abomasal digesta are presented for Sheep C and
D in Figures 1 and 2, respectively. The enrichments
of rumen ammonia N appeared to have reached
plateau values after about 10 h of 15 N-ammonia
infusion, although considerable variation in the
enrichments of ammonia was apparent. The
percentage of bacterial-N derived from ammonia-N
(from the period of 15N-ammonia infusion) was 53
63 % (ratio of plateau enrichments) and thus 37 47%
of bacterial-N was derived from NAN sources in
the rumen.
Figure 1 Enrichments (y axis; mol 15N/100 mol total ) versus time (x axis; h) in rumen fluid ammonia (○), rumen
fluid NAN (□) rumen bacterial-N (∆),abomasum ammonia (x) and abomasum NAN (◊) during a 72 h
administration of 2 µmol 15N/min as 15N-ammonia (top) or 15N-duckweed (bottom) for Sheep C
Figure 2 Enrichments (y axis; mol 15N/100 mol total ) versus time (x axis; h) in rumen fluid ammonia (○),
rumen fluid NAN (□) rumen bacterial-N (∆), reconstituted abomasum ammonia (x) and abomasum
NAN (◊) when 2 µmol 15N/min as 15 N-ammonia (top) or 15N-duckweed (bottom) was continually
supplied to the rumen (Sheep D).
Nitrogen Dynamics in the Rumen and Abomasum of Sheep (Damry and Nolan)
5
The total 15 N flow through the abomasum was
higher (P0.05
98.6
0.81
0.73
91.7
0.79
0.97
4.57
0.01
0.07
>0.05
>0.05
>0.05
0.50
0.81
10.4
0.50
0.81
9.98
0.02
>0.05
Values Determined when 15N-ammonia was Infused into The Rumen
Nitrogen Dynamics in the Rumen and Abomasum of Sheep (Damry and Nolan)
7
Table 1. Amounts of 15N Flowing in Various N Materials Through The Abomasum (mmol/d) During
a Continuous Provision into The Rumen of 15N-ammonia or 15N-Labelled Duckweed
15
15
N administered
N flow in abomasum NAN
15
N flow in bacterial-N
15
N flow in non-bacterial-N
15
N flow in abomasum ammonia-N
Total 15N flow through the abomasum
15
N absorbed from the rumen
15
15
N-ammonia
2.88
1.16
1.16
0.00
0.13
1.29
1.59
N-ammonia was infused into the rumen (not when
the tracer was provided by the 15N-duckweed as, in
this case, labelled NAN in the abomasum could be
non-bacterial in origin). The ratio, which was about
81 %, was assumed to apply throughout the
experiment and was also used in calculations for the
duckweed-ingesting animals. The ratio was higher
than that obtained for sheep with similar intakes of
DM by Siddons et al. (1982), and the estimates of
flow of bacterial-N through the abomasum (10.5 g
N/d), and the efficiency of bacterial-N synthesis (39
45 g N/kg DM apparently digested in the rumen, or
22 45 g N/kg DM truly digested in the rumen) also
seemed to lie at the high end of the range of published
values (SCA, 1990).
The proportion of duckweed-N that escaped
rumen fermentation was estimated from the data
describing the 15N balance across the rumen (Table
3). The 15N flowing through the abomasum would
have been present as both ammonia-N and NAN,
the latter consisting of microbial-N and non-microbialN. The non-microbial-N probably also contained
relatively small amounts of labelled endogenous
NAN. From the knowledge of bacterial-N enrichment
and the proportion of bacterial-N in the abomasal
NAN, the amount of 15 N in bacterial-N flowing
through the abomasum was calculated. Subtracting
the result from the total 15N flow gave an estimate of
the non-bacterial 15N-labelled NAN flow (0.85 mmol/
d). If the non-bacterial-N flow through the abomasum
is assumed to be solely from labelled escape
duckweed, then about 30 % of the duckweed N
ingested escaped digestion in the rumen which also
implies that about 70 % of the dietary duckweed-N
was degraded in the rumen. About 25 % of the 15N
8
15
N-duckweed
2.88
2.31
1.46
0.85
0.09
2.40
0.48
SEM
P
0.33
0.09