Effect of feeding long or short wheat hay v. wheat silage in the ration of lactating cows on intake, milk production and digestibility

Abstract

The objective of this study was to evaluate in lactating cows the effect of either chopping or ensiling of wheat roughage on: intake, digestibility, lactation performance and animal behavior. Three groups of 14 lactating cows each, were fed total mixed rations (TMRs) based on either long wheat hay (HL), short wheat hay (HS) or wheat silage (SI), as the sole roughage source (30% of TMR dry matter (DM)). Parameters examined: sorting behavior, DM intake, milk yield and composition, rumination, recumbence, average daily rumen pH, digesta passage rate, and in-vivo digestibility. Performance data was summarized by day and analyzed using a proc-mixed model. The content of physically effective neutral detergent fiber (peNDF) was similar in the HL and SI and lower in the HS, resulting in similar differences among the three corresponding TMRs. In vitro DM digestibility of wheat silage was higher than that of the two hays (65.6% v. 62.8%) resulting in higher in vitro DM digestibility of the SI-TMR compared with the hay-based TMRs (79.3 v. 77.0%). HS-TMR was better than HL- or SI-TMRs at preventing feed sorting by cows after 12 or 24 h eating of the diets. Cows fed HS-TMR consumed more DM and NDF but less peNDF than the other two groups. Average daily rumen pH was similar in the three groups, but daily rumination time was highest in the cows fed HS-TMR. Rumen retention time was longest in cows fed HL-TMR. DM digestibility in cows fed SI-TMR was higher than that of HS and HL groups (65.2%, 61.8% and 62.4%, respectively), but NDF digestibility was similar in the three treatments. The highest intake of digestible DM was observed in cows fed SI-TMR, HS cows were intermediate and HL cows were the lowest. Consequently, cows fed SI-TMR had higher yields of milk, 4% fat corrected milk and energy-corrected milk (47.1, 42.9 and 43.2 kg/day, respectively) than cows fed HS-TMR (45.7, 41.0 and 41.0 kg/day, respectively) or HL-TMR (44.1, 40.3 and 40.3 kg/day, respectively). Net energy production (NEL+M+gain) per kg DM intake was highest in the SI-TMR, lowest in the HS-TMR and intermediate in the HL-TMR (1.52, 1.40 and 1.45, respectively). Animal welfare, as expressed in daily recumbence time and BW gain was similar in the SI and HS groups and higher than the HL cows.

Full text

Effect of feeding long or short wheat hay
v
. wheat silage
in the ration of lactating cows on intake, milk production
and digestibility
Y. Shaani
1,2
, M. Nikbachat
1
, E. Yosef
1
, Y. Ben-Meir
1
, I. Mizrahi
3
and J. Miron
1†
1
Department of Ruminant Science, Agricultural Research Organization, HaMaccabim Road 68, P.O.B 15159 Rishon LeZion 7528809, Israel;
2
Department of Animal
Sciences, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100, Israel;
3
Dept of Life
Science, Faculty of Natural Sciences, Ben-Gurion University, P.O. Box 653 Beer-Sheva, Israel
(Received 27 September 2016; Accepted 3 March 2017; First published online 23 May 2017)
The objective of this study was to evaluate in lactating cows the effect of either chopping or ensiling of wheat roughage on:
intake, digestibility, lactation performance and animal behavior. Three groups of 14 lactating cows each, were fed total mixed
rations (TMRs) based on either long wheat hay (HL), short wheat hay (HS) or wheat silage (SI), as the sole roughage source
(30% of TMR dry matter (DM)). Parameters examined: sorting behavior, DM intake, milk yield and composition, rumination,
recumbence, average daily rumen pH, digesta passage rate, and
in-vivo
digestibility. Performance data was summarized by day
and analyzed using a proc-mixed model. The content of physically effective neutral detergent fiber (peNDF) was similar in the HL
and SI and lower in the HS, resulting in similar differences among the three corresponding TMRs.
In vitro
DM digestibility of wheat
silage was higher than that of the two hays (65.6%
v
. 62.8%) resulting in higher
in vitro
DM digestibility of the SI-TMR compared
with the hay-based TMRs (79.3
v
. 77.0%). HS-TMR was better than HL- or SI-TMRs at preventing feed sorting by cows after 12 or
24 h eating of the diets. Cows fed HS-TMR consumed more DM and NDF but less peNDF than the other two groups. Average daily
rumen pH was similar in the three groups, but daily rumination time was highest in the cows fed HS-TMR. Rumen retention time
was longest in cows fed HL-TMR. DM digestibility in cows fed SI-TMR was higher than that of HS and HL groups (65.2%, 61.8%
and 62.4%, respectively), but NDF digestibility was similar in the three treatments. The highest intake of digestible DM was
observed in cows fed SI-TMR, HS cows were intermediate and HL cows were the lowest. Consequently, cows fed SI-TMR had
higher yields of milk, 4% fat corrected milk and energy-corrected milk (47.1, 42.9 and 43.2 kg/day, respectively) than cows fed
HS-TMR (45.7, 41.0 and 41.0 kg/day, respectively) or HL-TMR (44.1, 40.3 and 40.3 kg/day, respectively). Net energy production
(NE
L+M+gain
) per kg DM intake was highest in the SI-TMR, lowest in the HS-TMR and intermediate in the HL-TMR (1.52, 1.40
and 1.45, respectively). Animal welfare, as expressed in daily recumbence time and BW gain was similar in the SI and HS groups
and higher than the HL cows.
Keywords: lactating cow performance, rumination, digestibility, wheat hay or silage, forage particle size
Implications
This study shows that feeding lactating cows with chopped
wheat hay might increase intake resulting in higher yields of milk
and energy-corrected milk than feeding long hay. In addition, this
study shows that feeding wheat silage-ration increases yields of
milk and energy-corrected milk compared with cows fed wheat
hay diets either long or chopped. Thus, when preparing diets
based on wheat, silage should get higher net energy value than
either chopped or long wheat hay (1.55
v
. 1.40 or 1.45 Mcal net
energy/kg dry matter (DM), respectively).
Introduction
With current annual production at over 735 million tons,
wheat is among the largest crop in the world, and an
essential source of carbohydrates for millions of people (FAO,
2015). In places over the globe suffering from lack of summer
falls, limited winter falls and winter-spring temperature up to
25°C, wheat has become the main forage used as hay, silage
or straw to feed productive ruminants (FAO, 2015). However,
although many studies have examined the effect of particle
size of temperate forages on rumen pH and digestibility,
there is limited knowledge about the effect of dietary phy-
sically effective neutral detergent fiber (peNDF) content on
†
E-mail: jmiron@agri.gov.il
Animal
(2017), 11:12, pp 2203–2210 © The Animal Consortium 2017
doi:10.1017/S1751731117001100
animal
2203

intake, digestibility, rumen pH and lactation performance in
cows fed diets based on wheat silage or hay as the sole
roughage source. Wheat silage and hay grown under hot
climate and limited amount of winter rainfall, are char-
acterized by low quality as expressed in high NDF content
(55% to 60% of DM) and limited
in-vitro
DM digestibility
(60% to 63%, Ben-Ghedalia
et al
., 1995). Such low-quality
roughages are included in lactating cow total mixed rations
(TMR) at a level of 30% to 35% of TMR DM to provide 18%
to 19% roughage-NDF in the diet as recommended (NRC,
2001). In such TMRs the maximal content of peNDF is around
11% of dietary DM. According to the literature, ruminal pH
should not be below 5.8 for more than 5 h/day, to minimize
health disturbances due to sub-acute ruminal acidosis
(SARA) (Zebeli
et al
., 2012). A model based on 64 studies and
257 different dietary treatments found that increasing the
content of peNDF to more than 18.5% of DM in lactating
cows rations, prevents SARA (Zebeli
et al
., 2010 and 2012).
In view of this model, rations based on low-quality rougha-
ges such as wheat hay or wheat silage fed at level of 30% to
35% of TMR DM supplying just 11% peNDF of DM, might
cause a risk of SARA to lactating cows. Our hypothesis is that
use of 30% wheat hay or silage as the sole roughage source
in lactating cow TMR is safe and does not cause SARA.
In contrast to wheat hay, the wheat used for ensiling
is usually harvested 2 to 3 weeks later at the soft-dough
stage of grain maturation, and therefore silage contains
less NDF and more nonstructural carbohydrate than hay.
Unfortunately, there is a lack of data pertaining to the effect
of wheat forage preservation method (silage
v.
hay) on
voluntary intake, rumen pH, digestibility and lactation
performance.
The objective of this study was to evaluate in lactating
cows the effect of feeding one of the three TMRs with various
wheat roughage sources (either short or long hay or silage),
on: voluntary intake, digestibility and lactation performance.
Rumen parameters including pH and rumination, cow
recumbence time and feed sorting by the cows, were also
measured in this study.
Material and methods
Forages and diets preparation
Composition and particle size distribution of the three wheat
forages are presented in Table 1, and those of the three TMRs
containing these forages are in Table 2. The three TMRs used
in this experiment were designed to be similar in roughage-
NDF content (17.9% of DM). Therefore, the two hay-based
TMRs consisted (on DM basis) of 70% concentrate mixture
and 30 wheat hay, whereas the silage-based TMR contained
higher forage level (32%) and lower level of added wheat
grains. Buffer was added (0.7% of DM) to all TMRs as
recommended (NRC, 2001). All wheat forages (Galil variety)
were grown in the same field (Yavne, Israel) on 400 mm
rainfalls. However, wheat hay was harvested at the early
stage of grain maturation while wheat for silage was
harvested at the soft-dough stage (as recommended for
wheat hay or silage). Upon our measurements at harvest, the
plants used for ensiling contained 20% of DM spikes and
80% vegetative mass, whereas the plants used for hay
contained only 10% of DM spikes and 90% vegetative mass.
Wheat hay was chopped in a chopping mixing wagon
with sharp knives (Siloking selfline 1000 +3024; Siloking
TM
,
Berlin, Germany) for either 5 min (hay long (HL)) or 30 min
(hay short (HS)). Ten tons of each hay type (short or long)
were prepared in large batch and preserved in separate barns
in Bet-Dagan. Portion of each hay type was mixed with the
concentrate mixture and water in a non-chopping mixing
wagon for 5 min before feeding the cows. The wheat for
silage was harvested by a chopping combine (3 to 6 cm
particle length), pressed and ensiled in polyethylene-
wrapped bales for 60 days before feeding (Shaani
et al
.,
2016) and kept in Bet-Dagan barn. A portion of the silage
was mixed with the concentrate mixture in non-chopping
mixing wagon for 5 min before feeding. The pH of wheat
silage was 4.2 and that of SI-TMR 4.9.
Structural and chemical analyses and
in vitro
digestibility
Hays and silage were sampled on a daily basis before mixing
into the TMRs. Dietary samples were taken daily from the
individual feeders immediately after feeding. The daily
samples were combined into a weekly pool during 6 weeks of
the experiment. Cows’orts were weighed and sampled daily.
Particle-size distribution of forages, TMRs and orts was
determined by a Penn State Particle Separator (PSPS),
equipped with a 19-mm screen (long), an 8-mm screen
(medium) and a pan (fine) (Lammers
et al
., 1996). The con-
tent (on DM basis) of peNDF remaining above the 8-mm and
19-mm sieves of the separator was designated as peNDF in
this study as recommended by (Yang and Beauchemin,
2006). Physically effective NDF was calculated according to
the equation of Kononoff
et al
. (2003): peNDF (g/kg DM) =g
wet fraction from the 8 +19 mm sieves ×% DM in separated
fraction ×% NDF in original DM sample/g DM sample
inserted.
Samples were dried in an aerated oven at 60°C for 48 h,
ground to pass a 1-mm screen in a hammer-mill (Retsch
S-M-100; Retch
TM
, Haan, Germany) and analyzed according
to AOAC (1990) for DM (method 925.40), total N (method
984.13), ether extract (EE, method 920.39) and ash content
(method 923.03). Crude protein in feeds was calculated as
N×6.25. Neutral detergent fiber (aNDF) was determined
according to Van Soest
et al
. (1991) using a heat-stable
amylase without sodium sulfite, and N bound to NDF was
determined (method 984.13). Acid detergent fiber and ADL
were determined using the sequential method of Van Soest
et al
. (1991). Hemicellulose was calculated as NDF −ADF
and cellulose as ADF −ADL. The Ankom Technology appa-
ratus (Ankom
220
, Macedon, NY, USA) was used for extract-
ing and filtering. Crude protein in NDF was measured
nonstructural carbohydrate (NSC) content was calculated as:
NSC (g/kg DM) =DM −CP (excluding NDF-bound pro-
tein) −NDF −EE −ash. The two-stage digestibility technique
Shaani, Nikbachat, Yosef, Ben-Meir, Mizrahi and Miron
2204

of Tilley and Terry (1963) was used to determine
in vitro
DM
digestibility of the feeds and TMRs (six weekly samples for
each TMR). Substrate (0.5 g, in four replicates per each feed
or TMR sample) was incubated in sealed 100 ml glass tubes
with 10 ml fresh screened rumen fluid and 40 ml buffer under
occasional shaking at 39°C for 48 h. Residual solids in tubes
were separated by centrifugation (1000 ×g) and the liquid
phase discarded. Fresh acidic solution of 40 ml 0.1 N HCL +
0.2% pepsin was inserted to each tube for a 2nd period of
48 h incubation as described above. The dry residual solids
remaining after centrifugation in each tube were designated
as the undigested fraction. The rumen fluid used for the
in vitro
measurement was obtained from two ruminally
fistulated dry Holstein cows, fed 7 kg (DM) of wheat hay and
3 kg (DM) of the wheat silage TMR.
Intake, sorting, recumbence, rumination and performance in
lactating cows
A total of 42 Israeli Holstein cows were randomly assigned to
three groups of 14 cows each that were similar at the onset
of the experiment (mean +SE) in lactation number
(3.0 ± 0.35), days in milking (132 ± 3.2) and milk yield
(49.5 ± 1.54 kg/day). The cows were adapted to the indivi-
dual dairy barn for 1 week, followed by 2 weeks of gradual
adaptation to one of the three TMRs, and 6 weeks of
experiment. The TMRs were fed individually once per day at
1000 h
ad libitum
, allowing for 5% to 10% orts, and cows
were milked three times per day at 0600, 1400 and 2200 h.
Cows were fed individually via a computerized monitoring
system, designed to electronically identify individual cows,
allowing entrance of each cow only into her designated
feeder, and to record each cow’s daily feed intake
(Miron
et al
., 2003). Daily dry matter intake (DMI) of indivi-
dual cows was determined based on DM content in TMR and
feed refusals sampled daily.
Sorting behavior of the cows was measured by weighting
orts and determining of DM intake and of wet particle dis-
tribution (0.5 kg DM orts or TMRs from weekly pool samples
of each cow) on the three sieves of the PSPS at 12 and 24 h
post feeding compared to the offered TMR. Sorting index was
calculated as the quantitative ratio between actual DM
intake of each particle-size fraction of the PSPS separator
(after 12 or 24 h) to predicted DM intake of each fraction
(assuming no sorting). A sorting index of 100 indicates
lack of any sorting (similar DM intake of the entire TMR and
each particle-size fraction measured). Sorting index below
100 indicates sorting by cows against non-consumed large
particle >8 or 19 mm. Sorting index above 100 indicates
preference to consume small particle (Leonardi and
Armentano, 2003).
Recumbence time for each cow, an indicator of animal
welfare (Drissler
et al
., 2005), was recorded daily by an
automatic meter located within each cow’s pedometer
(Afimilk Ltd., Kibbutz Afikim, Israel). Body weight data were
recorded by an automatic walk-over scale three times
per day while cows were entering the milking parlor.
Changes in BW were calculated as the gap between average
BW after adaptation at the week of the onset of the experi-
ment and at week 6 of the experimental period. The cows
were equipped with collar-mounted tags (HR-Tags; SCR
Engineers Ltd., Hadarim, Netanya, Israel) that monitored and
transmitted rumination time (Adin
et al
., 2009). Rumination
data were recorded during 6 weeks of the experiment by a
special microphone that detected rhythmal sound of rumi-
nation and chewing and separate it from eating sound by
analyzing vocal signals. Data were stored in 2-h blocks and
wire-less uploaded through antenna to the computer three
times daily at the milking parlor.
Milk yield (kg) and content of milk fat, protein and lactose,
were recorded daily for each cow by an automatic meter
equipped with on-line near-infra-red-spectroscopy measure-
ment (Afilab, Afimilk Ltd., Kibbutz Afikim, Israel). In parallel,
for validation of the online milk composition measurement,
milk samples were collected in three sequential milking’son
a weekly basis throughout the study, stored at 4°C in the
presence of 2-bromo-2-nitropropane-1,3-diol, until infrared
analysis for fat, protein, urea and lactose content, using
a MilkoScan 4000 analyzer (Foss Electric A/S, Hillerod,
Denmark).
Fat corrected milk (FCM) yield was calculated using the fol-
lowing equation (NRC, 2001): 4% FCM (kg/day) =0.4 ×milk
(kg/day) +15 ×fat (kg/day); energy-corrected milk (ECM)
yield was calculated using the following equation (NRC, 2001):
ECM (kg/day) =milk yield (kg/day) ×{[0.3887 ×milk fat
(%)] +[0.2356 ×milk protein –urea (%)] +[0.1653 ×milk
lactose (%)]}/3.1338 MJ/kg; energy for maintenance according
to cows’BWandenergyinBWgainwerecalculatedusingthe
following equation (NRC, 2001): NE
m
(Mcal) =kg BW
0.75
×
0.08; energy excreted in milk was calculated using the
following equation (NRC, 2001): NE
L
(Mcal/kg) =0.092 ×
fat (%) +0.0547 ×CP (%) +0.039 ×lactose (%); animal
performance study was conducted according to the guidelines
and under the supervision of ARO Animal Care Committee.
Digestibility and rumen pH measurements
After 2 weeks of adaptation and additional 4 weeks of the
experiment, 4 days were assigned for daily sampling of TMR,
feed refusals, and feces from three subgroups of seven cows
each fed the dietary treatments. Each subgroup was similar
in average ECM yield, DIM and DMI to the entire 14 cows
group. Estimation of daily fecal excretion was based on
indigestible NDF concentrations in feces, the TMRs and the
orts. Samples of the TMR and refusals were collected every
day during 42 days of experiment, composited per week (six
pool composites) for each cow, dried (60°C for 48 h), and
ground through a 1-mm sieve (S-M-100; Retsch GmbH,
Haan, Germany). Fecal grab samples were collected three
times daily for the same 4 days, at 8 h intervals, each day 3h
later than the preceding day. Fecal samples from each cow
were composited (on a DM basis), dried at 60°C for 48 h in a
forced-air oven, ground to pass through 1 mm sieve, and
then used for chemical analyses as described above, and
for indigestible NDF content in the TMR and fecal pooled
samples. The
in vitro
digestibility technique of Tilley and
Effects of wheat chopping or ensiling on lactating cows
2205

Terry (1963) was used to analyze the content of residual
indigestible NDF in the TMRs, orts and the pooled fecal
samples of each cow, after incubation with rumen fluid for
96 h followed by incubation for 48 h with HCl-pepsin (Adin
et al
., 2009). The quantitative ratio, indigestible NDF in TMR
ingested (without orts contribution)/indigestible NDF in feces, is
identical to the ratio fecal DM/DMI of each cow. Thus,
in vivo
DM digestibility was calculated according to the following
equation (Adin
et al
., 2009): DM digestibility =1−(TMR
ingested indigestible NDF/fecal indigestible NDF).
The digestibility values of each chemical component (i.e.
DM, CP, NDF, fat, cellulose, hemicellulose and NSC) were
calculated for every cow using its proportion between intake
(including orts sorting contribution) and fecal output
according to the equation presented in Adin
et al
. (2009).
These seven cows from each group were also sampled
every day during week 6 of the experiment for rumen fluid.
During this week cows were fed once a day at 0600 h for 1 h,
following by feed prevention for 6 h and then allowed to eat
for ad-lib intake. This feeding routine was chosen since pre-
liminary observations have demonstrated maximal and
minimal rumen pH at 1 h pre-feeding and 6 h post feeding,
respectively (Shaani
et al
., 2016). Rumen fluid of 400 ml were
collected from each cow with a rumen vacuum connected
to a self-made esophageal metal coated rubber pipe (2 m
length, 15 mm internal diameter) at 1 h pre-feeding and 6 h
after feeding. For each sample, in order to avoid saliva con-
tamination, the vacuum pump was turned on only after the
metal coated sampler pipe was inserted through the eso-
phagus and located in the floor of the ruminal sac, and the
first 200 ml of rumen fluid were discarded. The rumen pH
values were immediately determined by a portable pH-meter
(PL 600; MRC, Netanya, Israel). On the day after termination
of the data collection (shown in this paper), rumen fluid was
sampled every hour around the clock (from 0600 to 0500 h of
the next day), from seven cows of each treatment, in order to
measure SARA conditions identified as rumen pH below 5.8
for at least 3 h.
Statistical analysis
Comparisons among the three groups of 14 cows, each fed
one dietary treatment, with respect to individual DM intake,
BW changes, recumbence time, rumination time, yields of
milk, 4% FCM and ECM, and milk composition were sum-
marized by day and analyzed using a proc-mixed ANOVA in
JMP-5 software (SAS Institute, 2003), with day included as
repeated measures. Tukey’s test was used for comparisons
among means.
Subgroups of seven cows from each dietary treatment
(each subgroup was equal in average performance, DIM and
DMI to the entire 14 cows group) were used to compare
rumen pH,
in vivo
digestibility and sorting behavior among
treatments. Differences among treatments were tested for
significance by
F
-test using JMP-5 software (SAS Institute,
2003). Tukey’s test was used for comparison among means.
Results
Composition, intake, sorting and digestibility
The long wheat hay and the wheat silage had similar peNDF
content, higher (
P
<0.01) than that of the short wheat hay.
However, the wheat silage, that contained more NSC than
the hays (28.6%
v.
25.4%), was characterized by lower NDF
content and higher
in-vitro
DM digestibility than the two
hays (Table 1). These differences were reflected in higher
in vitro
DM digestibility of the SI-TMR than the two hay-
based TMRs (Table 2). Voluntary intake of DM and NDF was
significantly higher in cows fed the HS-TMR than in the SI
and HL groups (Table 3). The HS cows did not sort the TMR,
whereas, cows fed the HL and SI-TMRs demonstrated
significant sorting behavior after 24 h. The HL and SI cows
Table 1
Chemical composition of wheat silage and hays and their particle-size distribution with the Penn State Particle
Separator
Item Long hay Short hay Silage
Particle-size distribution (% of DM ± SD)
1
Long (>19 mm) 57.0 ± 1.38 43.0 ± 1.41 53.7 ± 1.44
Medium (>8 mm) 20.0 ± 1.09 17.1 ± 1.20 33.3 ± 1.31
Fine (<8 mm) 23.0 ± 0.72 39.9 ± 0.48 13.0 ± 0.60
peNDF
2
45.8 ± 2.35 35.8 ± 2.41 48.6 ± 2.47
Chemical composition (% of DM ± SD)
DM (% of wet) 92.3 ± 1.12 92.3 ± 1.16 38.6 ± 1.20
Organic matter 91.3 ± 1.64 91.3 ± 1.72 91.9 ± 1.68
NDF 59.6 ± 0.87 59.6 ± 0.90 55.9 ± 0.93
NDF-protein 2.40 ± 0.10 2.40 ± 0.09 2.55 ± 0.08
Ether extract 2.20 ± 0.09 2.20 ± 0.10 2.20 ± 0.08
Total CP 10.2 ± 1.73 10.2 ± 1.82 10.4 ± 1.64
Nonstructural carbohydrate 21.7 ± 2.46 21.7 ± 2.35 26.0 ± 2.57
In vitro
DM digestibility (%) 62.8 ± 0.17 62.8 ± 0.21 65.6 ± 0.13
1
Particle-size distribution was determined by the Penn State Particle Separator with a 19-mm screen (long), 8-mm screen (medium) and a
pan (fine).
2
peNDF =physically effective NDF remaining above the 8 mm plus 19 mm sieves of the separator.
Shaani, Nikbachat, Yosef, Ben-Meir, Mizrahi and Miron
2206

preferred to consume small dietary particle (<8 mm) and left
in the daily orts 16% and 7.7%, respectively, of the large
particle (>8 mm; Table 4). Higher consumption of peNDF was
demonstrated in the HL and SI cows compared with the HS
cows (
P
=0.05; Table 3). The cows fed SI-TMR had higher
digestibility of DM, CP, fat and NSC than the cows fed the HL
and HS treatments (Table 3). Apparent digestibility values of
NDF were similar in the three dietary treatments. Significant
differences were found among the three dietary treatments
in intake of digestible DM, which was highest in the SI cow,
intermediate in the HS cows and lowest in the HL group.
Rumen pH and rumination
Similar average rumen pH data were found in cows fed the
three dietary treatments (6.58 to 6.68; Table 5). Longer daily
rumination and rumination per kg DM ingested were found
in cows fed the SI-TMR, than in cows fed the two hay TMRs.
Milk yield and composition
The higher intake of digestible DM in the SI cows resulted in
6.8% and 3.1% higher milk yield of this group compared
with the HL and HS cows, respectively (Table 6). Milk fat
content was similar in the SI and HL groups and higher than
that of the HS cows, whereas milk protein content was higher
in the SI cows than in the hay fed groups. Consequently,
higher yields of 4% FCM and ECM were found in cows fed
the SI-TMR compared with the two groups fed the hay-based
TMRs. Average daily BW gain was higher in the SI and HS
cows than in the HL group.
Data of milk yield and composition, BW and BW gain was
used for calculation of energy produced (NE
L
Mcal in milk +
BW gain +maintenance) by cows fed the three TMRs.
Cows fed the SI-TMR produced more daily energy NE
L+M+gain
than the HS and HL groups (42.6, 40.8 and 40.3Mcal,
respectively). Thus, efficiency of energy production per kg
Table 2
Ingredients, structural and chemical composition of the three experimental total mixed rations (TMRs)
Long hay TMR Short hay TMR Silage TMR
TMR ingredients (% of DM)
Wheat silage (SI) ––32.0
Wheat hay, long (HL) 30.0 ––
Wheat hay, short (HS) –30.0 –
Dry ground corn 17.6 17.6 17.6
Dry ground barley 8.80 8.80 8.80
Dry ground wheat 7.90 7.90 5.90
Soybean meal 1.90 1.90 1.90
Rapeseed meal 2.20 2.20 2.20
Sunflower meal 4.50 4.50 4.50
Corn gluten feed 14.5 14.5 14.5
Dry distillers grain 7.50 7.50 7.50
Urea 0.10 0.10 0.10
CaCO
3
+NaCl 1.90 1.90 1.90
Ca-LCFA
1
2.30 2.30 2.30
NaHCO
3
0.7 0.7 0.7
Trace mineral–vitamin mixture
2
0.1 0.1 0.1
Water 38.0 38.0 –
Chemical composition (% of DM ± SD)
DM (% of wet) 63.5 ± 1.25 63.5 ± 1.10 63.5 ± 1.02
Organic matter 93.4 ± 2.12 93.4 ± 2.06 93.7 ± 2.18
CP 16.5 ± 0.91 16.5 ± 0.85 16.6 ± 0.97
NDF 32.1 ± 1.09 32.1 ± 1.03 31.3 ± 1.16
NDF-protein 0.77 ± 0.11 0.77 ± 0.12 0.80 ± 0.15
Roughage-NDF 17.9 ± 0.33 17.9 ± 0.30 17.9 ± 0.35
Ether extract 5.10 ± 0.65 5.10 ± 0.78 4.80 ± 0.82
Nonstructural carbohydrates 40.5 ± 1.69 40.5 ± 1.52 41.8 ± 1.63
In vitro
DM digestibility (% ± SD) 77.0 ± 0.20 77.0 ± 0.23 79.0 ± 0.16
Particle distribution (% of DM ± SD)
Upper sieve (>19 mm) 24.5 ± 1.49 13.0 ± 1.35 14.0 ± 1.41
Middle sieve (>8 mm) 9.50 ± 0.95 15.0 ± 0.98 18.8 ± 0.92
Bottom pan (<8 mm) 66.0 ± 1.81 72.0 ± 1.70 67.2 ± 1.62
peNDF
3
10.9 ± 0.42 8.90 ± 0.44 10.4 ± 0.40
DM =dry matter.
1
Calcium salts of long-chain fatty acids.
2
Containing (g/kg DM mix): Zn, 24; Fe, 24; Cu, 12.8; Mn, 24; I, 1.44; Co, 0.32; Se, 0.32; 16,000,000 IU of vitamin A; 3,200,000 IU of vitamin D
3
and 48,000 IU of vitamin E.
3
peNDF =physically effective NDF remaining above the 8 mm sieve.
Effects of wheat chopping or ensiling on lactating cows
2207

DMI was highest in the SI cows, intermediate in the HL
cows and lowest in the HS cows. Animal welfare, as
expressed in daily recumbence time and daily BW gain, was
similar in the SI and HS groups and higher than the HL cows
(Tables 5 and 6).
Discussion
Effect of wheat chopping on intake, digestibility and
rumen parameters
This study used three concentrated TMRs that were similar
in wheat forage NDF content (17.9% of DM). The HL and
SI-TMRs were also similar in dietary peNDF content (10.4%
to 10.9%), whereas the HS-TMR contained less peNDF
(8.9%; Table 2). Due to the lower peNDF content of the HS-
TMR, cows fed this diet consumed 4.4% and 3.9% more DM
than the cows fed the HL or SI-TMRs, respectively (
P
=0.05),
but ingested less peNDF. This is in accordance with the
guidelines stated by Zebeli
et al
. (2010 and 2012) about
effect of forage chopping on increasing DM intake. However,
the cows fed the three TMRs showed similar average rumen
pH (6.58 to 6.68; Table 5). This was expressed in similar
NDF digestibility of the three groups (Tables 3). A possible
explanation for these pH and NDF digestibility findings,
might be associated with the similar daily rumination length
of the HL and HS cows (Table 5). In addition, the higher
surface area of the short wheat hay particle, and the lack of
sorting by cows fed this diet (Table 4), encouraged adhesion
to and fast degradation of the short hay NDF components by
ruminal cellulolytic bacteria as previously suggested (Miron
et al
., 2001). These favorable conditions occurred despite of
the higher DM intake in cows fed HS-TMR compared with
cows fed the HL-TMR. These results are in accordance with
previous studies showing that decreasing peNDF content in
concentrated diets based on barley or corn silages improved
intake and NDF digestibility, positively affected rumen
fermentation, and reduced sorting behavior of the cows
(Kononoff
et al
., 2003; Yang and Beauchemin, 2006).
Using a model based on 64 studies and 257 different
dietary treatments, Zebeli
et al
. (2010 and 2012) found and
created guidelines that decreasing peNDF content in the TMR
below 185 g/kg DMI might reduce rumen pH below 5.8 and
create SARA conditions (Zebeli
et al
., 2010 and 2012). Not-
withstanding, results of the present study, show high rumen
pH and lack of SARA conditions in cows fed each of the three
TMRs, despite of their low peNDF content (in the range of
89.2 to 109 g/kg DM; Table 2). It is suggested that these
Zebeli’s guidelines are probably valid only for the high-forage
TMRs commonly used in the United States and Europe
(500 g/kg forage and 500 g/kg concentrates, Zebeli
et al
.,
2010), but are less valid for concentrated TMRs that contain
Table 3
Effects of the experimental total mixed ration (TMR) on intake
and
in vivo
digestibility
TMR
Item Long hay Short hay Silage SEM
P
-value
Intake
DM (kg/day) 27.8
b
29.2
a
28.1
b
0.10 0.01
DM (% of BM) 4.27
b
4.49
a
4.13
c
0.02 0.04
NDF (kg/day) 8.70
b
9.37
a
8.80
b
0.10 0.05
Digestible DM (kg/day) 17.3
b
18.0
ab
18.3
a
0.01 0.05
peNDF (kg/day)
1
2.78
a
2.60
b
2.81
a
0.01 0.05
Digestibility (%)
DM 62.4
b
61.8
b
65.2
a
0.80 0.02
NDF 44.9 44.1 46.8 1.00 0.35
Cellulose 39.0
a
34.9
b
40.2
a
0.90 0.05
Hemicellulose 49.2 50.8 51.1 0.96 0.45
CP 65.4
b
66.1
b
67.1
a
0.30 0.48
Ether extract 67.6
c
71.2
b
72.5
a
0.20 0.04
NSC
1
88.4
b
84.1
c
90.9
a
0.30 0.01
DM =dry matter.
a,b,
Means within row marked with different superscripts differ significantly at
P
<0.05.
1
NSC =non structural carbohydrate; peNDF =physically effective NDF remain-
ing above the middle sieve (8 +19 mm sieves) of the Penn State Particle
Separator; NDF and peNDF intake data were calculated considering composition
of orts residues.
Table 4
Sorting index
1
of the cows at different times post feeding
TMR
Item Long hay Short hay Silage SEM
P
-value
12 h post feeding time
Long particle >19 mm (%) 52.6
b
98.5
a
103.5
a
4.18 0.01
Medium particle >8 mm (%) 98.0 101.3 104.0 1.73 0.39
Fine particle <8 mm (%) 116
a
100
b
97.8
b
1.93 0.01
24 h post feeding time
Long particle >19 mm (%) 84.0
c
98.3
a
92.3
b
1.13 0.01
Medium particle >8 mm (%) 98.6 100 99.5 0.38 0.32
Fine particle <8 mm (%) 103
a
100
b
105
a
0.66 0.05
a,b,c
Means within row marked with different superscripts differ significantly at
P
<0.05.
1
Sorting index was calculated as the quantitative ratio (%) between actual intake (after 12 or 24 h) to predicted DM intake (without any sorting)
of each fraction retained on sieves of the Penn State Particle Separator. A sorting index of 100 indicates lack of any sorting (similar intake of the
TMR DM and the fraction). Sorting index below 100 indicates sorting by cows against non-consumed large particle >8 mm. Sorting index above
100 indicates preference to consume small particle (Leonardi and Armentano, 2003).
Shaani, Nikbachat, Yosef, Ben-Meir, Mizrahi and Miron
2208

only 300 to 320 g/kg DM wheat forage as used in this study
and in other semi-arid areas of the globe.
Effects of feeding wheat hay
v
. wheat silage
The effect of preservation method (wheat hay short or long
v.
wheat silage) on rumen parameters and NDF digestibility
was examined in this study. The HL-TMR and the SI-TMR
were similar in peNDF content but differed in TMR pH (4.7 in
the SI-TMR and 6.5 in the hay-based TMRs) and
in vitro
digestibility. However, cows fed these two TMRs presented
similar average rumen pH and had similar DM and NDF
intake and similar
in vivo
digestibility of NDF (Tables 3 and 4).
Moreover, SARA conditions (pH below 5.8 for 3 h) were not
identified in the present study in any of the three groups of
cows fed concentrated TMRs, probably because of the
addition of 0.7% NaHCO
3
buffer to the diets, and the high
daily rumination (448 to 480 min/day) of cows fed the three
TMRs. This high rumination rates supplied large quantities of
saliva containing internal buffer to the rumen that prevent
SARA conditions. These findings are in accordance with
previous studies (Jaakkola and Huhtanen, 1993; Murphy
et al
., 2000) which found no significant difference in rumen
pH of cows fed diets that contained either grass silage or
grass hay as the sole roughage source in the TMR.
In the present study, wheat silage was harvested at the
soft-dough stage of grain maturity, and thus contained 20%
spikes’mass, whereas the two hays were harvested at the
beginning of spikes maturation and contained only 10%
spikes’mass. This difference in composition increased
in vitro
DM digestibility of the wheat silage and SI-TMR while
reducing its NDF content compared with the hays (Tables 1
and 2). In accord, the
in vivo
digestibility of DM was highest
in cows fed the SI-TMR (Table 3). These intake and digest-
ibility data, resulted in differences among the three dietary
treatments with respect to digestible DM intake, which was
highest in the cows fed SI-TMR intermediate in the HS-TMR
Table 6
Lactation performance of cows fed the three experimental total mixed rations (TMRs)
TMR
Item Long hay Short hay Silage SEM
P
-value
Milk yield (kg/day) 44.1
c
45.7
b
47.1
a
0.26 0.03
Milk fat content (g/kg) 34.3
a
33.1
b
34.0
a
0.13 0.01
Milk protein content (g/kg) 30.0
b
29.8
b
30.7
a
0.07 0.01
Milk lactose content (g/kg) 49.9
b
49.9
b
50.1
a
0.04 0.05
4% fat corrected milk yield (kg/day) 40.3
b
41.0
b
42.9
a
0.25 0.03
Energy-corrected milk yield (kg/day) 40.3
b
41.0
b
43.2
a
0.24 0.03
Initial BW (kg) 649.6
b
648.1
b
677.3
a
3.32 0.04
Final BW (kg) 651.2
b
653.2
b
683.0
a
3.48 0.05
BW gain (g/day) 39.7
b
121.2
a
136.4
a
21.5 0.05
Retained energy in milk (Mcal NE
L
/cow per day)
1
30.0
b
30.5
b
32.1
a
0.17 0.05
Retained energy in BW gain (Mcal/cow per day)
2
0.003 0.010 0.011 0.0018 0.22
Maintenance energy (Mcal NE
M
/cow per day)
2
10.3 10.3 10.5 0.07 0.18
Energy produced (Mcal/cow per day)
3
40.3
b
40.8
b
42.6
a
0.24 0.05
Efficiency, (NE
L+M+gain
Mcal/kg intake)
3
1.45
b
1.40
c
1.52
a
0.01 0.05
a,b,c
Means within rows with different superscripts differ significantly at
P
<0.05.
1
Milk energy was calculated (NRC, 2001) as: NE
L
(Mcal/kg) =0.092 ×fat (%) +0.0547 ×CP (%) +0.039 ×lactose (%).
2
Energy for maintenance and energy retained in BW gain were calculated (NRC, 2001) as: NE
m
or BW
gain
(Mcal) =kg BW
0.75
×0.08.
3
Sum of daily energy produced =NE
L
+NE
m
+NE
BW −gain
.
Table 5
Rumen pH, rumination and recumbence behavior in lactating cows fed the experimental total mixed rations (TMRs)
TMR
Item Long hay Short hay Silage SEM
P
-value
Average rumen pH 6.68 6.58 6.59 0.11 0.65
Rumination (min/day) 448
b
455
b
480
a
1.65 0.01
Rumination (min/kg DM intake) 16.1
b
15.6
b
17.1
a
0.06 0.05
Rumination (min/kg NDF intake) 51.5
b
48.6
b
54.5
a
0.20 0.05
Rumination (min/kg peNDF intake) 161
b
175
a
171
a
0.69 0.04
Recumbence (occasions/day) 10.5 10.1 10.4 0.24 0.45
Recumbence (time, min/day) 508
b
551
a
547
a
2.69 0.01
DM =dry matter; peNDF >8mm =physically effective NDF remaining above the middle sieve (8 +19 mm sieves) of the Penn State Particle
Separator.
a,b,c
Means within rows with different superscripts differ significantly at
P
<0.05.
Effects of wheat chopping or ensiling on lactating cows
2209

and lowest in the HL-TMR (
P
=0.05; Table 3). These differ-
ences in digestible DM intake were expressed in daily milk
yield that presented similar trend (Table 6); the cows fed SI-
TMR had higher milk protein content and higher yields of 4%
FCM and ECM in compared with the hay fed groups. How-
ever, the larger content and ingestion of peNDF in the SI and
HL-TMRs resulted in higher milk fat content in cows fed
these two TMRs compared with cows fed the HS-TMR.
These differences among the three dietary treatments in
intake, digestibility, ruminal conditions and milk yield, were
expressed in the energy production of cows (NE
L+M+gain
Mcal/cow per day), which was higher in the SI cows than in
the hay fed cows. However, actual NE
L+M+gain
content per
kg TMR ingested was highest in the SI-TMR, lowest in the
HS-TMR and intermediate in the HL-TMR (1.52, 1.40
and 1.45 Mcal, respectively,
P
=0.05). Animal welfare, as
expressed in daily recumbence time and BW gain was similar
in the SI and HS groups and higher than the HL cows.
Conclusions
This study shows that in a concentrated TMR containing only
30% to 32% wheat forages, short wheat hay is better than
long wheat hay or wheat silage at preventing feed sorting
and increasing intake. Replacing long wheat hay with wheat
silage (containing 20% spikes mass) increased DM digest-
ibility and intake of digestible DM, and resulted in higher
yields of milk, 4% FCM and ECM by lactating cows.
Production efficiency of the diet was highest in the cows fed
SI-TMR lowest in the cows fed HS-TMR and intermediate in
the HL-TMR (1.52, 1.40 and 1.45 Mcal NE
L+M+gain
/kg DMI,
respectively).
Acknowledgments
The authors express their appreciation to Yavne Feeding Center
for the TMR production. This study was supported by the Israeli
Dairy Board Foundation projects 362-0342 and 362-0375.
References
Adin G, Solomon R, Nikbachat M, Zenou A, Yosef E, Brosh A, Shabtay A,
Mabjeesh SJ, Halachmi I and Miron J 2009. Effect of feeding cows in early
lactation with diets differing in roughage-neutral detergent fiber content on
intake behavior, rumination, and milk production. Journal of Dairy Science 92,
3364–3373.
AOAC 1990. Official methods of analysis, vol. 1, 15th edition. Association of
Official Analytical Chemists, Arlington, VA.
Ben-Ghedalia D, Kabala A and Miron J 1995. Composition and in vitro
digestibility of carbohydrates of wheat plants harvested at bloom and
soft-dough stages. Journal of the Science of Food and Agriculture 68, 111–116.
Drissler M, Gaworski M, Tucker CB and Weary DM 2005. Free stall maintenance:
effects on lying behavior of dairy cattle. Journal of Dairy Science 88, 2381–2387.
FAO 2015. Food and Agriculture Organization of the United Nations, food outlook
biannual report on global food markets, p. 11. Retrieved on January 2016 from
http://www.fao.org/3/a-i5003e.pdf.
Jaakkola S and Huhtanen P 1993. The effects of forage preservation method and
proportion of concentrate on nitrogen digestion and rumen fermentation
in cattle. Grass Forage Science 48, 146–154.
Kononoff PJ, Heinrichs AJ and Lehman HA 2003. The effect of corn silage particle
size on eating behavior chewing activity, and rumen fermentation in lactating
dairy cows. Journal of Dairy Science 86, 3343–3353.
Lammers B, Buckmaster D and Heinrichs A 1996. A simple method for the
analysis of particle sizes of forage and total mixed rations. Journal of Dairy
Science 79, 922–928.
Leonardi C and Armentano LE 2003. Effect of quantity, quality, and length of
alfalfa hay on selective consumption by dairy cows. Journal of Dairy Science 86,
557–564.
Miron J, Ben-Ghedalia D and Morrison M 2001. Invited review:
adhesion mechanisms of rumen cellulolytic bacteria. Journal of Dairy Science 84,
1294–1309.
Miron J, Yosef E, Maltz E and Halachmi I 2003. Soybean hulls as a replacement
of forage neutral detergent fiber in total mixed rations of lactating cows. Animal
Feed Science and Technology 106, 21–28.
Murphy M, Akerlind M and Holtenius K 2000. Rumen fermentation in lactating
cows selected for milk fat content fed two forage to concentrate ratios with hay
or silage. Journal of Dairy Science 83, 756–764.
NRC 2001. Nutrient Requirements of Dairy Cattle, 7th revised edition.
Subcommittee on Dairy Cattle Nutrition, Committee on Animal Nutrition
and Board on Agriculture and Natural Resources/National Academy Press,
Washington, DC.
SAS Institute 2003. SAS for windows ver. 9.1.3. SAS Institute Inc., Cary, NC,
USA.
Shaani Y, Eliyahu D, Mizrahi I, Yosef E, Ben-Meir Y, Nikbachat M, Solomon R,
Mabjeesh SJ and Miron J 2016. Effect of feeding ensiled mixture of pomegranate
pulp and drier feeds on digestibility and milk performance in dairy cows. Journal
of Dairy Research 83, 35–41.
Tilley JMA and Terry RA 1963. A two-stage technique for the in vitro digestion of
forage crops. Journal of the British Grassland Society 18, 104–111.
Van Soest PJ, Robertson JB and Lewis BA 1991. Methods for dietary fiber,
neutral detergent fiber and non-starch polysaccharides in relation to animal
nutrition. Journal of Dairy Science 74, 3583–3597.
Yang WZ and Beauchemin KA 2006. Effects of physically effective fiber on
chewing activity and ruminal pH of dairy cows fed diets based on barley silage.
Journal of Dairy Science 89, 217–228.
Zebeli Q, Aschenbach JR, Tafaj M, Boguhn J, Ametaj BN and Drochner W 2012.
Invited review: role of physically effective fiber and estimation of dietary
fiber adequacy in high producing dairy cattle. Journal of Dairy Science 95,
1041–1056.
Zebeli Q, Mansmann D, Ametaj BN, Steingass H and Drochner W 2010.
A model to optimise the requirements of lactating dairy cows for
physically effective neutral detergent fibre. Archives in Animal Nutrition 64,
265–278.
Shaani, Nikbachat, Yosef, Ben-Meir, Mizrahi and Miron
2210