SEMIÁRIDA Revista de la Facultad de Agronomía UNLPam Vol 29(1): 3341
6300 Santa Rosa Argentina. 2019.
ISSN 24084077
(online)
CONTRASTING LEVELS OF FRUCTOSE AND UREA ADDED TO AN ANNUAL
RYEGRASS BASED DIET: EFFECTS ON MICROBIAL PROTEIN SYNTHESIS,
NUTRIENT DIGESTIBILITY AND FERMENTATION PARAMETERS IN
CONTINUOUS CULTURE FERMENTERS
NIVELES CONTRASTANTES DE FRUCTOSA Y UREA AGREGADOS A UNA
DIETA BASADA EN RAIGRÁS ANUAL: EFECTOS SOBRE SÍNTESIS DE
PROTEÍNA MICROBIANA, DIGESTIBILIDAD DE NUTRIENTES Y PARÁMETROS
DE FERMENTACIÓN EN FERMENTADORES DE FLUJO CONTINUO
Alende Mariano 1,2,*, Gustavo J. Lascano1, Thomas C. Jenkins1
& John G. Andrae1
Recibido 07/09/2018
Aceptado 25/05/2019
ABSTRACT
The objective of this experiment was to evaluate the effects of the addition of crystalline fructose
and urea to an annual ryegrassbased diet on microbial protein synthesis, fermentation profile and
nutrient apparent digestibility, using continuous culture fermenters. Six fermenters were used in a 3 x
2 factorial arrangement with three levels of water soluble carbohydrates (WSC) obtained by crystalline
fructose addition (21, 24 and 27 g.100 g DM1; LWSC, MWSC and HWSC, respectively) and two levels
of CP obtained by urea addition (14.6 and 18.6 g.100 g DM1, LCP and HCP, respectively). Four 10d
periods were ran sequentially (7d for adaptation, 3d for sampling). Microbial protein synthesis was
assessed by purine to N ratio. There was a positive interaction between WSC and CP level on
microbial protein synthesis (P<0.001). Water soluble carbohydrate level did not affect fermentation
pH, ammonia concentration or total volatile fatty acids concentration (VFA). Greater CP levels also
increased acetic acid proportion and tended to increase acetic to propionic acid ratio, whereas WSC
level did not affect VFA proportions. Treatments did not affect nutrient digestibility. We conclude that
the addition of crystalline fructose to annual ryegrass samples increased microbial protein synthesis
at the greater levels of CP in diet.
KEY WORDS: annual ryegrass, continuous culture, crude protein, microbial protein synthesis, water
soluble carbohydrate
RESUMEN
El objetivo de este experimento fue evaluar los efectos de la adición de fructosa cristalina y urea a
una dieta basada en raigrás anual sobre la síntesis de proteína microbiana, la fermentación y la
digestibilidad de los nutrientes, usando fermentadores de flujo continuo. Se usaron seis fermentadores
de flujo continuo en un arreglo factorial 3x2, con tres niveles de hidratos de carbono solubles (WSC)
obtenidos por la adición de fructosa cristalina (21, 24 y 27 g.100 g MS1; LWSC, MWSC y HWSC,
respectivamente) y dos niveles de proteína bruta (CP) obtenidos por la adición de urea (14,6 y 18,6
g.100 g MS1, LCP y HCP, respectivamente). Se corrieron sucesivamente cuatro períodos de 10d (7d
para adaptación, 3d para muestreo). La síntesis de proteína microbiana se estimó por la relación
purinas:N. Hubo una interacción significativa entre niveles de WSC y CP para síntesis de proteína
microbiana (P<0,001). El nivel de WSC no afectó el pH, la concentración de amonio ni la concentración
de ácidos grasos volátiles (VFA). Niveles más altos de CP aumentaron la proporción de ácido acético
y tendieron a aumentar la relación acético propiónico, mientras que el nivel de WSC no afectó las
proporciones de VFA. Los tratamientos no afectaron la digestibilidad de los nutrientes. Concluimos que
la adición de fructosa cristalina a dietas basadas en raigrás anual aumentó la síntesis de proteína
microbiana a los niveles más altos de CP en la dieta.
Cómo citar este trabajo:
Alende, M., Lascano, G. J., Jenkins, T. C., & Andrae, J. G..
PALABRAS CLAVE: Raigrás anual, fermentadores de
(2019). Contrasting levels of fructose and urea added to an
flujo continuo, proteína bruta, síntesis de
annual ryegrass based diet: effects on microbial protein
proteína microbiana, hidratos de carbono
synthesis, nutrient digestibility and fermentation parameters
solubles
in continuous culture fermenters. Semiárida, 29(1), 3341.
1 Clemson University, Department of Animal and Veterinary Sciences, Clemson, SC 29634
2 Instituto Nacional de Tecnología Agropecuaria INTA, 6326 Anguil, La Pampa, Argentina
* alende.mariano@inta.gob.ar
Alende, M., Lascano, G. J., Jenkins, T. C., & Andrae, J. G.
INTRODUCTION
MATERIAL AND METHODS
Rumen microbes are able to synthetize
Treatments
microbial protein from nonprotein N sources
Six treatments were designed by a 3 x 2
(Clark et al., 1992). For this synthesis to be
factorial arrangement of treatments, with three
efficient, water soluble carbohydrates (WSC) to
levels of WSC (21, 24 and 27 g.100 g DM1;
CP ratio (WSC:CP) seems to be determinant
LWSC, MWSC and HWSC, low, medium and
(Johnson, 1976; Edwards et al., 2007; Hall &
high WSC, respectively) and 2 levels of CP
Huntington, 2008). Hoover and Stokes (1991)
(14.6 and 18.6 g.100 g DM1, LCP and HCP, low
analyzed a range of NSC:RDP ratios within 2
and high CP, respectively); levels were designed
and 10 and found that lower ratios led to higher
to be within the possible range of annual
microbial crude protein synthesis. However,
ryegrass. A sample of dried (60ºC, 48 h) and
high quality grasses
(i.e., annual ryegrass,
ground (2mm sieve) annual ryegrass (Lolium
Lolium multiflorum) often can often show ratios
multiflorum, var Enhancer, Sucraseed, OR)
lower than 2, from which little is known. This
harvested at the stage of flag leaf emergence was
imbalance in turn leads to ammonia buildup in
used as the basic feed to which crystalline
the rumen, which microorganisms cannot
fructose (Tate & Lyle, Decatur, IL, US, 99%
efficiently capture (Stern et al., 1978) reducing
purity) and ground urea were added (Table 1).
N use inefficiency (Da Silva et al., 2014).
Feed analysis included determinations of NDF
Temperate grasses store energy in the form of
(Van Soest et al., 1991), ADF (AOAC, 2000),
fructans, commonly called water soluble
lignin
(Goering & Van Soest,
1970), CP
carbohydrates (WSC) or sugars. Grass WSC:CP
(AOAC,
2000),
soluble
protein
ratio can vary due to several factors (Parsons et
(Krishnamoorthy et al.,
1982), degradable
al., 2004; Mayland et al., 2005; Gregorini et al.,
protein (Krishnamoorthy et al., 1983), WSC
2006; Moorby et al., 2006; Cosgrove et al.,
(Dubois et al., 1956; Hall, 2013), ether extract
2007). Fructans are readily available to
(AOAC, 2000), and starch content (Hall, 2009).
microorganisms immediately after entering the
Continuous culture fermenters
rumen (Johnson, 1976), thus providing carbon
The six dualflow continuous culture
skeletons and energy. Therefore, increased
fermenters used in this experiment were a
supply of WSC in diets high in nonprotein N
modified version of the design described by
could improve N efficiency and microbial
Teather and Sauer (1988). Solid passage rate was
protein synthesis (Mansfield et al., 1994). In
set at 5%. h1 and liquid dilution rate at 12%.h1,
fact, Edwards et al. (2007) reviewed several
by regulating the buffer infusion pumps at 90
research articles in dairy cattle and found that as
mL.h1. Each treatment was run for four 10d
WSC:CP ratio increases, the proportion of
periods sequentially (7d for adaptation, 3d for
nitrogen lost by urine decreases. On the other
sampling). Whole rumen contents were taken
hand, it is known that microbial protein
from cannulated Holstein dairy cows fed a ration
synthesis depends partially on N supply. Most
comprised of corn silage, grass hay and a grain
research shows that increasing true protein
mix diet. All surgical and animal care protocols
supply, in the form of polypeptides,
were approved by the Clemson University
oligopeptides or aminoacids, enhance microbial
Animal Care and Use Committee (Protocol
growth over ammonia (Hoover & Stokes, 1991),
2016034). Liquid and solid ruminal contents
but little is known about the ability of
were transported to the laboratory and
microorganisms to capture inorganic N at
homogenized in a blender while purged with
contrasting levels of WSC supply. The objective
CO2. The blended mix was filtered through
of this experiment was to create contrasting
double layer cheesecloth and mixed with the
WSC:CP ratios adding urea and fructose to an
buffer (Slyter et al., 1966) at a 1:1 ratio and
annual ryegrass based diet, to evaluate the effect
added into the continuous culture fermenter
on microbial protein synthesis, fermentation and
vessel (approximately 750mL total volume).
digestibility
34
Contrasting levels of fructose and urea added to an annual ryegrass based diet: effects on microbial protein synthesis, nutrient
digestibility and fermentation parameters in continuous culture fermenters
The temperature was kept at
39.5°C by a
1986). Apparent DM, NDF and ADF
circulating heated water bath (Julabo, PA, USA).
digestibilities were estimated through simple
Fermenters were constantly purged with CO2
weight differences between fed and outflow, while
true DM digestibility was calculated subtracting
(20 mL.min1). Fermenters were fed 20 g DM of
bacterial DM outflow. Neutral detergent fiber and
the respective treatment per day at 0800 and
ADF content of the overflow were estimated in an
1600.
ANKOM 2000 analyzer (Van Soest et al., 1991).
Sample collection and measurements
Samples from overflow were treated to isolate a
bacterial pellet in which to estimate the N to purine
Overflow volume was recorded daily in
ratio, using differential centrifugation. Purine
refrigerated vessels. After measuring volume, a
content in bacterial pellet and overflow was
10mL sample of overflow was taken with a wide
determined according to Zinn and Owens (1986).
mouth (0.8 mm opening) pipette. This sample was
used to estimate overflow DM content. Samples
Samples from the culture were collected at 2,
of overflow were kept to estimate NDF and ADF
0, 2, 4, 6 and 8 h, with 0 h being the first daily
content, as well as to estimate the N to purine ratio
feeding time at
0800. Culture pH
(Hanna
and microbial protein synthesis (Zinn & Owens,
Instruments, Woonsocket, RI) was recorded at the
same sampling times (plus an additional
measurement at 1 h). A 4ml sample
Table 1. Chemical composition of diets based on annual ryegrass
differing in water soluble carbohydrates and crude protein
was transferred into polycarbonate
content, fed to continuous culture fermenters
tubes containing 1ml of 25g.100ml1
Tabla 1 Composición química de las dietas basadas en raygrás
metaphosphoric acid. These samples
anual con diferentes contenidos de hidratos de carbono
were used to determine ammonia and
solubles y proteína bruta en fermentadores de flujo
VFA concentration.
Ammonia
continuo.
concentration was estimated by
colorimetric technique
(Chaney &
Diet
Marbach, 1962).
g.100 g DM1
LWSC
MWSC
HWSC
Volatile fatty acid concentrations
LCP HCP
LCP HCP
LCP HCP
were analyzed by gas chromatography
with flame ionization detector on a
CP
14.4
18.7
15.0
18.0
14.5
19.1
Zebron ZBFFAP 30 m x 0.25 mm x
0.25μm column
(Phenomenex,
SP
5.2
9.3
5.4
9.4
5.0
9.6
Torrance, CA). The injection volume
RDP
9.8
14.0
10.2
13.7
9.8
14.5
was 0.1 μl and samples were injected
with a split ratio 10:1. Injector was kept
NDF
49.2
49.0
47.4
46.5
45.4
46.1
at 270°C and detector at 250°C. The
ADF
30.2
29.5
29.3
29.2
28.9
30.8
carrier gas was hydrogen at a flow rate
of
26.9 mL.min1. Column oven
ADL
2.9
4.2
2.5
2.9
2.5
2.4
temperature was programmed to
WSC
21.2
21.0
24.1
24.5
27.1
26.9
increase from 120 to 150°C at a rate of
12°C.min1, and from 150 to 220°C at a
EE
2.8
1.9
2.8
2.3
2.7
2.2
rate of 20 °C.min1. Standard curves
Starch
2.3
2.2
1.3
2.0
1.1
1.0
were run for each VFA using a standard
VFA mix (SigmaAldrich VFA mix,
Water soluble carbohydrates: LWSC = 21 g WSC.100g DM1, MWSC: 24g
PA, US) to estimate total VFA
WSC.100g DM1, HWSC 27 g WSC.100g DM1; LCP: 14.6g CP.100g DM1,
concentration (mM) as well as the molar
HCP: 18.6g CP.100g DM1. CP= crude protein, SP= soluble protein, RDP=
proportions of individual VFA.
Ruminally degradable protein, aNDF= neutral detergent fiber (residual ash
included), ADF= acid detergent fiber, ADL= lignin (sa), WSC= water soluble
carbohydrates, EE= ether extract.
Statistical analyses
Hidratos de carbono solubles: LWSC = 21g WSC.100g DM1, MWSC: 24g WSC.
Dry matter, aNDF and ADF
, HCP: 18,6g
100g DM1, HWSC 27g WSC.100g DM1; LCP: 14,6g CP.100g DM1
digestibilities, as well as microbial
CP.100g DM1. CP= proteína bruta, SP= proteína soluble, RDP= Proteína
protein synthesis data, were analyzed
degradable a nivel ruminal, aNDF= Fibra detergente neutro incluyendo cenizas,
ADF= fibra detergente ácido, ADL= lignina, WSC= hidratos de carbono solubles,
using the mixed procedure of SAS
EE= extracto etéreo
35
Alende, M., Lascano, G. J., Jenkins, T. C., & Andrae, J. G.
(SAS Inst., Inc., Cary, NC) based on the
a quadratic effect of WSC level on average pH,
following model: Yijk= μ + γi + πj + γπij + ρk +
with MWSC resulting in the lowest values
θl + εijkl, where Yijk is the observed value, μ is
(Table 2). There was no interaction between
the overall mean, γi is the WSC effect (i= 1 to
WSC and CP level, or between WSC and
3), πj is the CP effect (j= 1 to 2), γπij is the
sampling hour for pH (P > 0.05); however, there
interaction between WSC and CP, ρk is the
was an interaction between CP and sampling
random effect of period (k = 1 to 4), θl is the
hour (P = 0.003, Figure 1). At 1 h and 2 h post
random effect of fermenter, and εijkl is the
feeding, pH was greater in HCP than in LCP
experimental error. Ammonia, VFA, and pH data
(Figure 1). On the other hand, HCP showed
were analyzed with repeated measures using the
greater ammonia concentration
(Table
2),
mixed procedure of SAS (SAS Inst., Inc., Cary,
because once in the rumen, urea is rapidly
NC). Linear and quadratic contrasts were used
converted into ammonia. Ammonia level peaked
to evaluate the effect of WSC. Significance was
in HCP at 2 h postfeeding and then slowly
determined at P < 0.05. Differences at 0.05 < P
decreased, but always showed greater levels of
< 0.10 were discussed as trends.
ammonia than LCP
(Figure
2). Greater
concentrations of ammonia agreed with greater
Results and Discussion
pH detected in HCP at 1 and 2 h post feeding,
Fermentation parameters and nutrient which reflects that urea had a buffering effect,
digestibility
as previously shown by Wanapat et al. (2009).
On the other hand, WSC level had no effect on
There was no effect (P = 0.43) of CP on
ammonia levels, which contrasts with the
average pH (6.28 vs 6.34, for LCP and HCP,
findings of Kim et al. (1999), who reported that
respectively, Table 2). There was a tendency to
Table 2. Total and individual volatile fatty acids, ph and ammonia concentration in continuous culture fermenters fed
annual ryegrass differing in water soluble carbohydrates and crude protein content
Tabla 2. Concentración de ácidos grasos volátiles totales e individuales, pH y amonio en fermentadores de flujo
continuo alimentados con dietas basadas en raigrás anual variando el contenido de hidratos de carbono
solubles y proteína bruta
CP level
WSC level
P value
SEM
SEM
LCP HCP
LWSC MWSC HWSC
CP WSC lin WSC quad WSC x CP
pH
6.27
6.34
0.07
6.38
6.21
6.32
0.05
NS NS
**
NS
NH4+
5.95
13.82
0.70
10.17
9.44
10.04
0.74
**
NS
NS
NS
VFATotal mM
2.65
34.84
41.57
37.71
2.46
NS NS
**
NS
(mM.100 mM1)36.8639.22
Acetic
46.01
50.49
0.79
50.04
47.02
47.70
1.22
**
NS
NS
NS
Propionic
26.17
24.97
0.86
24.90
25.82
25.99
1.02
NS NS
NS
NS
Isobutyric
0.72
0.63
0.04
0.66
0.69
0.69
0.05
†
NS
NS
NS
Butyric
17.21
16.05
0.67
16.35
16.94
16.61
0.71
NS
NS
NS
Isovaleric
1.66
1.27
0.24
1.41
1.64
1.35
0.24
**
NS
NS
Valeric
5.62
4.44
0.42
4.38
5.28
5.42
0.49
†
NS
NS
A:P
1.78
2.04
0.07
2.03
1.84
1.86
0.10
†
NS
NS
NS
LWSC, MWSC and HWSC, low, medium and high water soluble carbohydrates, 21, 24 and 27g WSC.100g DM1. LCP and HCP, low
and high crude protein, 14.6 and 18.6g.100g DM1. A:P= acetic to propionic ratio. SEM= Standard error mean. NS= not significant.
Significance of the CP, WSC and their interactions were denoted by †=P<0.10, *=P<0.05, **=P<0.01
LWSC, MWSC and HWSC, nivel bajo, medio y alto de hidratos de carbono solubles, 21, 24 y 27g WSC.100g DM1. LCP y HCP, nivel
bajo y alto de proteína bruta, 14,6 y 18,6g.100g MS1. A:P= relación acético:propiónico. SEM= error estándar de la media. NS= no
significativo. La significancia de CP, WSC y sus interacciones se señala por: †=P<0,10, *=P<0,05, **=P<0,01
36
Contrasting levels of fructose and urea added to an annual ryegrass based diet: effects on microbial protein synthesis, nutrient
digestibility and fermentation parameters in continuous culture fermenters
feeding.
Concentration of WSC resulted
in a quadratic effect on total VFA
concentration (P = 0.04, Table 2),
the latter being greater in MWSC.
This is consistent with the lower
pH found in MWSC, since total
VFA is an important determinant
of pH (Dijkstra et al, 2012). The
individual VFA molar proportions
were not affected by WSC, except
for a trend (P= 0.08) to a linear
increase in valeric acid with
Figure 1. Continuous culture fermenters pH at different times post feeding
resulting from diets containing low (14.6g.100g DM1) or high
increasing WSC level (Table 2).
(18.6g.100g DM1) CP concentrations (sampling time x CP
Contrastingly, Berthiaume et al.
interaction, P = 0.003). Error bars = 0.0810, standard error of
(2010)
reported
greater
the mean. Asterisk indicates differences (P < 0.05) between
diets within sampling time.
proportion of propionate and
butyrate as well as lower
Figura 1. Promedio de pH diario en fermentadores de flujo continuo a
diferentes horarios post alimentación, resultante de dietas
proportion of acetate in cattle fed
conteniendo bajo (14,6g.100g MS1) y alto (18,6g.100g MS1)
alfalfa with greater nonstructural
contenido de CP (interacción horario de muestreo x CP P=
carbohydrate content. Kim et al.
0,003) . Barras de error= 0,0810, error estándar de la media.
(1999) reported greater molar
Los asteriscos indican diferencia significativas (P<0,05) entre
medias.
proportion of butyric acid in
maltodextrin supplemented cattle.
However, in both studies, the
treatments affected ruminal pH,
thereby it is impossible to
elucidate if the changes in VFA
profile were due to substrate, pH
or both.
On the other hand, CP level
affected both acetic and butyric
acid molar proportion (Table 2).
The proportion of acetic acid was
greater in HCP than in LCP,
whereas the opposite occurred
Figure 2. Continuous culture fermenters ammonia concentration at
different times post feeding resulting from diets containing low
with butyric acid. Acetic to
(14.6g.100g DM1) or high
(18.6g.100g DM1) CP
propionic acid ratio tended to be
concentrations. Error bars = 0.928, standard error of the mean.
greater in HCP treatments (P=
Asterisk indicates differences (P < 0.05) between treatment
0.06), even though no differences
means.
were detected in propionic acid
Figura 2. Concentración de amonio en fermentadores de flujo continuo a
concentration. Finally, HCP level
diferentes tiempos post alimentación con dietas conteniendo
bajo (14,6g.100g MS1) y alto (18,6g.100g MS1) contenido de
also showed a lower molar
CP. Barras de error= 0,928, error estándar de la media. Los
proportion of isovaleric and
asteriscos indican diferencia significativas
(P<0,05) entre
valeric acid
(Table
2).
In a
medias.
continuous culture experiment,
Calsamiglia et al.
(2008)
ruminal infusion of maltodextrin reduced rumen
analyzed the effect of both pH and diet on VFA
ammonia concentration and reduced the peak of
concentration and concluded that pH affected
ammonia concentration immediately after
37
Alende, M., Lascano, G. J., Jenkins, T. C., & Andrae, J. G.
both acetate and butyrate concentrations.
et al., 2001; Calsamiglia et al., 2008; Disjktra et
Culture pH explained 81% of the observed
al., 2012). Our average pH values were above
variation in acetate concentration, which
6.0 in all the treatments, which implies that the
increased 23.7 mM for each unit increase in pH.
fermentation environment supported a good
In the case of butyrate, pH explained 36% of the
fiber fermentation even at the greater levels of
variation, being both factors negatively related.
WSC. On the other hand, the lack of effect of
Even though the relation between VFA
urea addition on DM and fiber digestibility
proportions and pH is more complex, it seems
coincides with reports by Stern et al. (1978).
that culture pH had an effect affecting both
Microbial protein synthesis
acetate and buyrate proportion.
There was an interaction among CP and WSC
Neither WSC level nor CP level affected
level (P<0.001) on microbial protein synthesis
(Table 3) apparent DM digestibility (51.39g.100g
(Figure 3). At the lower level of CP, there was
DM1, on average), true DM digestibility
no effect of WSC on microbial protein synthesis,
(58.58g.100g DM1, on average), NDF
whereas at the greater level of CP, increasing the
digestibility (49.21g.100g DM1, on average) or
level of WSC led to greater microbial protein
ADF digestibility
(40.87g.100g DM1, on
synthesis (Figure 3). Kim et al. (1999) reported
average). Coincident with our findings,
greater microbial protein synthesis when
Mansfield et al. (1994) did not find significant
supplying maltodextrin either synchronized with
effects of diet NSC concentration on DM
protein supply or in a continuous infusion.
digestibility. With respect to the effect of highly
Coincidently, Henning et al. (1991) found that a
fermentable carbohydrates on fiber digestion, it
pulse dose of WSC at feeding time was the most
has been studied previously (Calsamiglia et al.,
effective way to increase microbial growth in
2008) and it seems that those effects are also
batch culture. Forages under direct grazing
mediated by pH, which is one of the most
sometime contain high concentration of soluble
important factors affecting fibrolytic bacteria
protein and an imbalance between WSC and
activity (Russell and Wilson, 1996). Several
highly soluble protein availability (Merry et al.,
researchers have shown that fiber digestibility is
2006). This has led to the selection of forage
reduced when average pH is below 6.0 (Mouriño
varieties greater in WSC, which should lead to
Table 3. Dry matter, NDF and ADF digestibility of annual ryegrass differing in water soluble carbohydrates and crude
protein content, fed to continuous culture fermenters
Tabla 3. Digestibilidad de la FDN, FDA y MS de raigrás anual variando su contenido de hidratos de carbono solubles
y proteína bruta, en fermentadores de flujo continuo
CP level
WSC level
P value
g.100g DM1
SEM
SEM
LCP HCP
LWSC MWSC HWSC
CP WSC lin WSC qua WSC x CP
App IVDMD
52.65
50.13
1.75
51.62
51.07
51.48
2.01
NS NS
NS
NS
True IVDMD
58.61
58.55
1.31
58.29
58.04
59.42
1.60
NS NS
NS
NS
NDFD
50.62
47.81
2.21
49.87
48.92
48.85
2.48
NS NS
NS
NS
ADFD
42.03
39.72
2.59
44.01
40.66
37.94
3.22
NS NS
NS
NS
Water soluble carbohydrates: LWSC = 21g.100g DM1, MWSC: 24g.100g DM1, HWSC 27g.100g DM1; CP (crude protein) content:
LCP: 14.6g.100g DM1, HCP: 18.6g.100g DM1. IVDMD= in vitro dry matter digestibility, NDFD= neutral detergent fiber in vitro digestibility,
ADFD= acid detergent fiber in vitro digestibility, WSC= water soluble carbohydrate main effect, CP = crude protein main effect, WSC x
CP = water soluble carbohydrate x crude protein interaction. NS= not significant. Significance of the CP, WSC and their interactions
were denoted by †=P<0.10, *=P<0.05, **=P<0.01
LWSC, MWSC and HWSC, nivel bajo, medio y alto de hidratos de carbono solubles, 21, 24 y 27g WSC.100g DM1. LCP y HCP, nivel
bajo y alto de proteína bruta, 14,6 y 18,6g.100g MS1. IVDMD= digestibilidad in vitro de la materia seca, NDFD= digestibilidad in vitro
de la FDN, ADFD= digestibilidad in vitro de la FDA, SEM= error estándar de la media. NS= no significativo. La significancia de CP,
WSC y sus interacciones se señala por: †=P<0,10, *=P<0,05, **=P<0,01
38
Contrasting levels of fructose and urea added to an annual ryegrass based diet: effects on microbial protein synthesis, nutrient
digestibility and fermentation parameters in continuous culture fermenters
improvements in N use efficiency. Berthiaume
high sugar ryegrass varieties in an in vitro
et al.
(2010) reported that high NSC alfalfa
system, found that the efficiency of N use was
varieties increased the efficiency of N use by
greater for highsugar ryegrass silage than
bacteria. Similarly, Merry et al. (2006), using
control. Additionally, in an in vivo experiment,
high
WSC concentration
perennial ryegrass varieties led to
lower
rumen
ammonia
concentration, greater microbial N
flows to the duodenum and
greater efficiency of microbial
protein synthesis (Merry et al.,
2006). Once in the rumen, WSC
(i.e., fructans and fructose) go
quickly into solution and would
therefore be available for rapid
fermentation, yielding ATP and
VFA that can later be used in
Figure 3. Microbial crude protein synthesis (g.d1) in continuous culture
combination with N sources in the
fermenters from diets containing low (14.6g.100g DM1) or high
(18.6g.100g DM1) CP concentrations and low (LWSC= 21g.100g
synthesis of microbial protein
DM1), medium (MWSC= 24g.100g DM1) and high (HWSC=
(Johnson,
1976). That would
27g.100g DM1) WSC content. Error bars = 0.150, standard error
explain
the
lower
VFA
of the mean. Different letter means statistical differences (P< 0.05).
concentration found in HWSC
Figura 3. Síntesis de proteína microbiana (g.d1) en fermentadores de flujo
continuo alimentados con dietas con bajo (14,6g.100g MS1) y
compared to MWSC, because
alto (18,6g.100g MS1) contenido de CP y bajo (LWSC= 21g. 100g
part of the produced VFA would
MS1), medio
(MWSC= 24g.100g1) y alto (27g.100g MS1)
have been used for synthesis of
contenido de WSC a 3 diferentes niveles de hidratos de carbono
solubles (WSC) y 2 niveles de proteína bruta en la dieta (CP).
bacterial aminoacids. Increasing
Barras de error= 0,150, error estándar de la media. Letras
forage WSC concentration, either
diferentes indican diferencias estadísticamente significativas
by genetic improvement of
(P<0.05)
varieties (Cosgrove et al., 2007)
Table 4. Nitrogen digestion and bacterial crude protein synthesis of annual ryegrass based diets differing in water
soluble carbohydrates and soluble protein content, fed to continuous culture fermenters
Tabla 4. Digestión de la fracción nitrogenada y síntesis de proteína microbiana en dietas basadas en raigrás difiriendo
en contenido de hidratos de carbono soluble y proteína bruta, usando fermentadores de flujo continuo
CP level
WSC level
P value
g.100 g DM1
SEM
SEM
LCP HCP
LWSC MWSC HWSC
CP WSC lin WSC qua WSC x CP
N intake (g.d1)
2.38
3.03
2.69
2.69
2.74
N outflow (g.d1)
0.74
0.75
0.03
0.76
0.74
0.74
0.04
NS NS
NS
NS
N digestion (g.100 g1)
68.96 74.99 1.41
71.31
72.25
72.36
1.63
**
NS
NS
NS
Bact N.total N outflow1
0.39
0.41
0.05
0.40
0.39
0.42
0.05
NS NS
NS
NS
CP synth (g.100 ADDM1) 8.52
9.35
0.65
8.72
8.53
9.56
0.81
NS NS
NS
NS
CP synth (g.100 TDDM1) 7.42
8.03
0.50
7.59
7.44
8.15
0.61
NS NS
NS
NS
Water soluble carbohydrates: LWSC = 21g.100g DM1, MWSC: 24g.100g DM1, HWSC 27g.100g DM1; CP (crude protein) content:
LCP: 14.6g.100g DM1, HCP: 18.6g.100g DM1. N= nitrogen. CP synth = bacterial crude protein synthesis, expressed as g.100g of
apparent digested DM1 (ADDM) and as g.100g of truly digested DM1 (TDDM). NS= not significant. Significance of the CP, WSC and
their interactions were denoted by †=P<0.10, *=P<0.05, **=P<0.01
LWSC, MWSC and HWSC, nivel bajo, medio y alto de hidratos de carbono solubles, 21, 24 y 27g WSC.100g DM1. LCP y HCP, nivel
bajo y alto de proteína bruta, 14,6 y 18,6g.100g MS1. N= nitrógeno, CP synth= síntesis de proteína microbiana, expresado como g.100g
de MS aparentemente digerida1 (ADDM) y como g.100g de MS realmente digerida1 (TDDM). NS= no significativo. La significancia
de CP, WSC y sus interacciones se señala por: †=P<0,10, *=P<0,05, **=P<0,01
39
Alende, M., Lascano, G. J., Jenkins, T. C., & Andrae, J. G.
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41
