Feedstuff production is not enough to meet the requirement in Turkey. Approximately
16-17 tons of forage dry matter are produced from pastures and ranges each year.
These amounts are 20-25% of the annual forage requirement. The Southeastern
Anatolia between production and need has tried to be full with creal crop residues
such as straw (Saricicek and Okuyan, 1993). Thereby, in
order to fulfill animals nutrient requirement, more concentrate feed has
to be fed resulting in an increase in feed cost. Turkey is one of top sugar
beet producing countries. Sugar beet by products such as wet or DSBP have high
cellulose digestibility and thus are very cheap energy source for ruminant in
Turkey (Deniz et al., 2001).
Ruminal pH is normally buffered by bicarbonate ions of saliva. Lowering percentage of forage in ration causes a decrease in chewing and rumination that stimulate secretion of saliva on the other hand it increases acid formation in the rumen. While concentrations of VFA increase, ruminal pH decrease as a result of rapid degradation of carbohydrate in concentrate feed in the rumen leading a significant alteration of ruminal bactria population.
Number of lactic acid bacteria thus, lactic acid production increase in the
rumen resulting in acidosis (Coskun, 1998; Orskov,
1990). Sodium bicarbonate and MgO are the agents most commonly used against
acidosis. These agents can be included 0.5-2.5% in diets (Coskun,
The response of animal to these agents depends on forage/concentrate ratio of diet, feed intake and amounts of buffer in diet. The aim of this study was to evaluate the effects of buffers (NaHCO3 and MgO) and substitution of barley with DSBP on milk yield, milk composition, rumen fermentation and some blood parameters in dairy cows.
MATERIALS AND METHODS
This research was carried out in a dairy farm. Four Holstein cows with similar
age, lactation period and milk yield were utilized. Cows with second phase of
lactation were chosen. Chemical compositions of feed used in the experiment
were analyzed as described by Weende (Akkilic and Surmen,
1979) system. Treatments consisted of control (40% Barley), control+1% NaHCO3
(NaHCO3), control + 1% NaHCO3 + 0.5% MgO (MgO) and barley
substituted with DSBP. All diets were calculated to be isocaloric and iso-nitogeneous
(Table 1). To determine the amount of NaHCO3 and
MgO, literature values were used (Senel, 1992; Worley
et al., 1986; Erdman et al., 1980,
The experiment was a 4x4 Latin square design with 15 day of initial adaptation
period. The experiment consisted of 4 periods with 20 days adaptation and 7
days sampling period, a total of 27 days. Nutrient requirements of animals were
determined using NRC (1988) values. Cows were milked twice
a day and amounts of milk measured for each milking to determine daily milk
yield during each sampling period. About 1% of milk were sampled at each milking.
Then, 0.5% saturated HgCl2 was added into milk to stop fermentation
just after sampling.
Approximately 10 mL blood from V. jugularis and 100 mL rumen fluid
from rumen were collected 3 h post-feeding from each animal for each period.
Ruminal pH were determined immediately after sampling. Ruminal NH3-N
concentrations were determined after necessary treatments were done (Demirel
and Bolat, 1996) as soon as possible. A dublicate of rumen fluid were taken
into tubes (3 mL) and stored at -20°C for VFA analysis. Serum were drawn
from blood and stored at -20°C for analysis.
|| Composition of concentrate feed mix used in the experiment
|a: Premix provided per kg of diet: Vit A 5.000.000 IU; Vit.
D3, 1.000.000 IU; Vit. E, 25.00 mg; b: Suplied (per kg of diet):
Mn, 40.000.000 mg; Fe, 50.000.000 mg; Zn, 40.000.000 mg; Cu,10.000 mg; I,
500 mg; Co, 100 mg; Se, 100 mg; *: NaHCO3 and MgO were added
to feed mixes after feed mix was prepared
Milk samples were analyzed for Dry Matter (DM), Crude Protein (CP), ash (Akkilic
and Surmen, 1979) and fat (Kurt et al., 1993).
Concentration of lactose in milk samples were calculated with an equation described
by McDowell and McDaniel (1968) as follows:
Lactose (%) = Solid matte (%)-(CP%-0.7x ash%)
While milk yields corrected for Solid Matter (SCM) were calculated according
to Tyrell and Reid (1965) milk yields corrected for
4% fat (4% FCM) were calculated according to Jurgensen (1982)
using following formulas:
SCM (lb) = 12.3 (F) + 6.56 (SNF)-0.0752 (M)
4% FCM (kg day-1) = MY (0.4+0.15 x FY)
||Fat yield lb day-1
||Milk yield lb day-1
||Milk yield kg day-1
||Fat yield kg day-1
While DM, ash, CP and Ether Extract (EE) concentrations of feedstuff were analyzed
with a method described by Weende (Akkilic and Surmen, 1979),
Crude Fiber (CF) contents were determined with the method of Crampton and Maynard
(Akkilic and Surmen, 1979). Serum total protein, glucose
levels were determined by Chema Protein (Total)® and Chema Glucose
FL (Fast)® kits using spectrophotometry. Serum Ca, P and urea
levels were analyzed by an auto analyzer. Volatile Fatty Acid (VFA) concentrations
of rumen fluid were determined using HPLC. Rumen ammonia-N levels were analyzed
using thedistillation unit of Kjeldahl apparatus (Deniz
and Tuncer, 1995).
RESULTS AND DISCUSSION
Chemical composition of forage and concentrate feedstuff used in the experiment
are shown in Table 2. Daily milk yield, composition of milk,
forage intake, 3 h post-feeding ruminal pH, NH3-N, total VFA, acetic
acid, propionic acid, butyric acid, lactic acid, acetic/propionic acid ratios,
serum total protein, glucose, urea, Ca and P levels are shown in Table
3. Chemical composition of forage and concentrate feedstuff used in the
experiment are shown in Table 2. Chemical composition of diets
were similar except diet containing DSBP. While concentrations of ash and CF
were higher, concentrations of EE and NFE were less in DSBP diet compared with
other diets resulted from the substitution of barley with DSBP. Because CF digestibility
of DSBP is very high (Deniz et al., 2001), this
difference in CF contents of diets is not very important.
|| Chemical compositions of forage and concentrate used in the
|| Forage intake, milk yield, composition of milk, ruminal fermentation
and some blood parameters of cows
|x: Total VFA consist of acetid, propionic and butiryc acids:
a-cValues with different letter in the same line indicate significant
Although, it was not statistically significant, the highest forage intake
was observed in animals fed DSBP diet (Table 3).
Some researchers have indicated that DSBP increased feed intake by increasing
palatability of diet (Tyrell and Reid, 1965;
Jurgensen, 1982). While amount of concentrate given was fixed, animals had
free access to forage in this study. Even though there was little variation
among animals and periods, forage/concentrate ratio was generally 2:1.
Daily milk yiels were 10.37, 11.03, 11.44 and 10.67 kg day-1 for control, NaHCO3, NaHCO + MgO and DSBP diets, respectively (p<0.05). Daily milk yield was significantly higher in animals fed NaHCO3 + MgO supplemented diet compared with animal fed control diet (p<0.05) but similar with other groups (Table 3). Solid corrected and fat corrected milk yields were similar among treatments.
Similar to the results, many studies reported an improvement in milk yield
(Erdman et al., 1980; West
et al., 1991; Schneider et al., 1986;
Tucker et al., 1993; Rogers et al., 1985)
but only one study indicated a decrease in milk yield with buffer supplementation
(Aslam et al., 1991). Schneider
et al. (1986) fed diets containing 38% silage, 62% concentrate supplemented
with 1% NaHCO3, 0.73 NaCI and 1.3 or 1.8% potasium to 19 kg daily
milk producing cows. Addition of NaHCO3 into diet significantly increased
milk yield, fat corrected milk yield, fat content of milk. In another study,
Fisher and Mackay (1983) supplemented control diet with
180 g NaHCO3. Cows fed NaHCO3 supplemented diet had significantly
higher milk yield and fat corrected milk yield but less lactose in milk compared
with cows fed control diet. Concentrations of milk fat and protein did not differ
About 3 h post-feeding ruminal pH values were similar among treatments, ranging
from 6.77-6.99. Considering the 2:1 forage/concentrate ratio of diets, these
pH values are in normal range. Addition of buffers into diets increased ruminal
pH when animals were fed diets low in fiber (Kilmer et
al., 1981; Thomas et al., 1984).
Neither buffering agents nor source of carbohydrate did not significantly affect
ruminal NH3-N concentrations (Table 3). All ruminal
NH3-N values were above the levels (5-7 mg dL-1) required
for optimal microbial protein synthesis in the rumen (Deniz
and Tuncer, 1995). Kilmer et al. (1981)
have reported that dairy cows fed 0.8% NaHCO3 supplemented diets
had significantly higher `ruminal NH3-N concentrations compared with
control group. It was speculated that this increase in ruminal NH3-N
concentrations resulted from increased ruminal protein degradation due to increased
pH. On the other hand, Stokes et al. (1986) fed
cows with diets containing 0.7% NaHCO3 or 0.7% NaHCO3
+ 0.28% MgSO4 only animals fed diet supplemented with 0.7% NaHCO3
had significantly greater ruminal NH3-N concentrations compared with
other groups. DePeters et al. (1984) have reported
that supplementing control diet with NaHCO3 above 0.25% of DM did
not increase in fact decreased ruminal NH3-N concentrations.
One of the most important finding of this study was that both NaHCO3 and NaHCO3 + MgO supplementations increased concentrations of acetic acid and decreased concentrations of propionic acid in the rumen. Concentrations of acetic acids were 50.26, 65.22, 62.64 and 50.38 mmo L-1 for control, NaHCO3, NaHCO3 + MgO and DSBP diets, respectively (p<0.05). The concentrations of propionic acids were significantly greater in the rumen of cows fed control diet compared with those fed other diets.
These changes in concentrations of acetic and propionic acids caused by buffering
agents were reflected at acetic acid/propionic acid ratios. Thus, acetic acid/propionic
acid ratios were the highest in cows fed diets supplemented with buffering agents
followed by DSBP (p<0.05). It has been reported that NaHCO3 and
MgO supplementation of diets increased acetic acid concentrations and decreased
propionic acid concentrations via increasing rate of passage from rumen (Thomson
et al., 1978; Harrison et al., 1975).
Use of artificial saliva at 4 and 8% as buffering agents increased rate of liquid
passage thus decreased concentration of propionic acid (Harrison
et al., 1975). Similar to the results, many researchers (Erdman
et al., 1980; West et al., 1987;
Staples et al., 1988) have reported that buffering
agents increased acetic acid, decreased propionic acid concentrations in the
rumen thus caused a high acetic/propionic acid ratios in dairy cows. About 3
h post-feeding serum total protein, urea, glucose, Ca and P levels were similar
among treatments (Table 3).
Serum total protein levels were 8.59, 8.83 and 8.85 g mL-1 for NaHCO3,
NaHCO3 + MgO and DSBP, respectively. These values were a little above
the levels known as normal (6.0-8.5 g mL-1) in the literature. However,
serum total protein levels of control were in the range of normal levels (8.41
g mL-1). Serum urea levels (6.0-36.0 mg dL-1) were in
agreement with the values reported in the literature (Altintas
and Fidanci, 1993; Imren and Sahal, 1990). Even though
serum glucose levels were in the range of normal levels (Altintas
and Fidanci, 1993; Imren and Sahal, 1990) it was
over (81.96 mg dL-1) normal levels in animals fed diet supplemented
with NaHCO3. Serum Ca levels were 7.28, 7.58 and 6.75 mg dL-1
for NaHCO3+MgO, DSBP and control diets, respectively. These values
were at lower edge of normal Ca levels reported for cows (Altintas
and Fidanci, 1993; Imren and Sahal, 1990). However,
serum Ca levels of animals fed diet supplemented with NaHCO3 were
in the range of normal values. Serum P levels were in agreement with the values
reported in the literature.
Similarly, Rogers et al. (1985) have reported
that 1.2% NaHCO3 supplementation did not affect serum total protein,
glucose, Ca and P levels. Addition of NaHCO3 into diet increased
serum Ca levels about 1.2 mg dL-1 (Kilmer et
al., 1980). This increase was thought to be caused by the increase in
absorption of Ca in the intestine due to alteration of intestinal pH which was
revealed as an increase in blood. Tucker et al. (1988)
have reported that addition of 1.4% NaHCO3 did not alter serum Ca
levels. In contrast, Staples et al. (1988) noted
an increase in serum Ca levels but not P levels by addition of NaHCO3.
Addition of NaHCO3 or NaHCO3 + MgO increased milk yield but did not affect composition of milk. An increase in ruminal acetic acid concentrations and acetic/propionic acid ratio due to buffering agent is an important finding. It must be revaluated the use of supplements in feeding diets since they decrease propionic acid level.