Frequency of concentrate supplementation for cattle fed
barley straw. 1. Effect on voluntary intake, ruminal
straw disappearance, apparent digestibility and
heat production
R. C. Tellier1, G. W. Mathison1, E. K. Okine1, D. McCartney2, and R. Soofi-Siawash1
1Department
of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta,
Canada T6G 2P5 (e-mail: [email protected]); and 2Agriculture and Agri-Food Canada,
Lacombe Research Centre, 6000 C&E Trail, Lacombe, Alberta, Canada T4L 1W1.
Received 28 July 2003, accepted 10 March 2004.
Tellier, R. C., Mathison, G. W., Okine, E. K., McCartney, D. and Soofi-Siawash, R. 2004. Frequency of concentrate supplementation for cattle fed barley straw. 1. Effect on voluntary intake, ruminal straw disappearance, apparent digestibility
and heat production. Can. J. Anim. Sci. 84: 455–465. Five ruminally cannulated crossbred steers (474 ± 30 kg) were fed diets
containing 70% barley straw and 30% concentrate in an unbalanced 5 × 5 Latin square design experiment to investigate the effects
of frequency of feeding barley grain-based concentrates (daily, alternate days or every third day) with different dietary protein
(7.9 and 11.5%) on voluntary intake of straw, ruminal disappearance of straw, apparent digestibility, and heat production. Neither
frequency of feeding nor dietary protein concentration influenced voluntary intake of straw, nor did cattle eat differing amounts of
straw on days when concentrate was fed in comparison with days when concentrate was not fed. Protein supplementation increased
(P < 0.01) 24-h ruminal straw disappearance, but did not affect disappearances at other times. Concentrate feeding frequency had
no influence on rate of ruminal disappearance of straw. Apparent digestibilities of dry matter, gross energy, acid detergent fibre
(ADF) and crude protein were 5, 6, 8 and 33% higher (P < 0.05), respectively, in diets containing the high-protein concentrate,
but were not affected by frequency of concentrate feeding. Heat production (kJ kg-0.75) tended to be reduced (P = 0.06) by 4% in
steers fed concentrate on alternate days in comparison with steers fed concentrate daily. Dietary protein concentration had no influence on heat production even though digestible energy intake was 10% higher when the high protein concentrate diet was fed. It
was concluded that concentrate can be fed every second day without any negative impact on intake and digestibility, with a possible benefit of a reduction in energy lost as heat. More research, however, is required to study the feasibility of feeding concentrate every third day.
Key words: Cattle, straw, protein, feeding frequency, digestion, heat production
Tellier, R. C., Mathison, G. W., Okine, E. K., McCartney, D. et Soofi-Siawash, R. 2004. Fréquence des apports de concentré
pour les bovins nourris de paille d’orge. 1. Incidence sur l’indice de consommation, la disparition de la paille dans le rumen,
la digestibilité apparente et la production de chaleur. Can. J. Anim. Sci. 84: 455–465. Cinq bouvillons hybrides (474 ± 30 kg)
canulés au rumen ont reçu un régime composé à 70 % de paille d’orge et à 30 % de concentré dans le cadre d’une expérience en
carré latin 5 × 5 non équilibré qui devait préciser les effets de la fréquence à laquelle un concentré d’orge à teneur variable en protéines (7,9 et 11,5 %) était servi (tous les jours, un jour sur deux ou aux trois jours) sur l’indice de consommation de la paille, la
disparition de cette dernière dans le rumen, la digestibilité apparente et la production de chaleur. Ni la fréquence ni la concentration de protéines n’ont d’influence sur l’indice de consommation de la paille et les animaux ne mangeaient pas une quantité différente de paille les jours où on leur donnait le concentré. Le supplément de protéines augmente (P < 0,01) la quantité de paille
disparue du rumen au bout de 24 heures, mais n’affecte pas le volume de paille digérée dans d’autres laps de temps. La fréquence
à laquelle le concentré est distribué n’influe pas sur la vitesse de disparition de la paille dans le rumen. La digestibilité apparente
de la matière sèche, de l’énergie brute, des fibres au détergent acide et des protéines brutes s’accroît respectivement de 5, 6, 8, 8
et 33 % (P < 0,05) avec le concentré le plus protéique, mais la fréquence à laquelle ce concentré est servi n’exerce aucune influence sur ce plan. Les bouvillons recevant le concentré un jour sur deux ont tendance à produire 4 % moins (P = 0,06) de chaleur
(kJ par trois quarts de kilo) que ceux le recevant tous les jours. La concentration de protéines dans l’aliment n’agit pas sur la quantité de chaleur produite,même si les animaux recevant le concentré très protéique absorbent 10 % plus d’énergie digestible. On en
conclut qu’on pourrait servir le concentré un jour sur deux sans répercussion négative sur l’indice de consommation et la digestibilité, avec une éventuelle diminution de la quantité d’énergie perdue sous forme de chaleur. Des recherches plus poussées s’imposent
pour établir la faisabilité d’un régime avec apport de concentré un jour sur trois.
Mots clés: Bovins, paille, protéines, fréquence des repas, digestion, production de chaleur
Abbreviations: BW, body weight, DM, dry matter; ADF, acid detergent fibre; Low-1, low protein concentrate fed daily; Low-2,
low protein concentrate fed on alternate days; High-1, high protein concentrate fed daily; High-2, high protein concentrate fed on
alternate days; High-3, high protein concentrate fed every third day; NDF, netural detergent fibre
455
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CANADIAN JOURNAL OF ANIMAL SCIENCE
An Alberta study found that provision of winter feed represented 33% (range 17 to 48%) of input costs in cow-calf
production systems in 1998 (Alberta Agriculture, Food and
Rural Development 2003). Feeding cereal straw can reduce
the cost of feeding pregnant cows in the winter. Major concerns with feeding straw are low voluntary intake, low protein content, poor digestibility, low mineral and vitamin
concentrations, and slow passage rate (Anderson 1978).
Provision of supplemental feeds to straw-based diets is
expensive, however, thus cattle producers in western
Canada and western United States are studying the feasibility of reducing frequency of providing supplemental feeds
to less than once daily as a cost-cutting measure.
Research concerning infrequent feeding of supplemental
feeds has yielded variable results. Voluntary intake and
digestibility were not influenced by frequency of supplementation in studies of Chase and Hibberd (1989) and Hunt
et al. (1989) whereas Collins and Pritchard (1992) reported
an 8% decrease in dry matter (DM) intake when steer calves
were fed soybean meal and corn gluten meal supplements
on alternate days rather than daily. Beaty et al. (1994)
reported that straw intake was decreased when cattle were
fed concentrate three times rather than seven times weekly
but the digestibility of neutral detergent fibre (NDF) was
increased. Variable results have also been reported with
respect to animal performance. McIlvain and Shoop (1962),
who both fed a high protein supplement daily or every third
day, and Huston et al. (1999) did not detect any detrimental
effect of reduced frequency of feeding on weight changes.
However Collins and Pritchard (1992) and Beaty et al.
(1994) found negative effects of reduced feeding frequency
on weight changes.
The variable conclusions arrived at by researchers with
respect to the effect of reduced frequency of feeding supplemental feeds may be due to the differing dietary protein contents and feedstuffs used and the length of time between
feeding. It is known, for example, that the addition of a feed
to a diet may influence the digestibility of another feed, and
that feed type may influence these “associative effects”. Thus
Kay et al. (1968) reported that the digestibility of straw was
not reduced when a barley straw diet was supplemented with
barley grain, whereas digestibility of NDF was decreased
when sorghum grain was added to an ammoniated wheat
straw-based diet in the study of Fike et al. (1995). In an examination of the literature it became apparent that no information
on feeding concentrates less frequently than once daily is
available with respect to: (1) barley straw, and (2) the energetic efficiency of cattle, as assessed through measurements
of heat production. For these reasons, and because the
responses to reduced frequency of feeding of supplemental
feeds are variable, this experiment was conducted to provide
additional information on reduced frequency of concentrate
feeding with barley-straw-based diets. Alternate-day feeding
of concentrates, or the extreme of every second day feeding
of concentrates, was examined since further reductions in
feeding frequency could probably not be defended nor recommended commercially with straw-based diets.
The objectives of this study were to investigate the
hypotheses that the provision of concentrates containing low
and high protein levels on alternate days or concentrate with
high protein level every third day would have no influence
on voluntary intake of barley straw, in vivo digestibility, or
heat production of steers.
Additional information concerning liquid and particulate
dilution rates in the rumen and ruminal metabolites was also
obtained (Tellier et al. 2004).
MATERIALS AND METHODS
Animals, Feed and Feeding Regimen
Five crossbred steers (474 ± 30 kg) were used in the 5 × 5
Latin square experiment to examine the effects of frequency
of feeding barley-grain-based concentrates with straw-based
diets on voluntary straw intake, ruminal degradability of
straw, diet digestibility and efficiency of energy use. The
experiment was conducted at the Laird McElroy
Environmental and Metabolic Centre, University of Alberta,
Edmonton, Alberta, Canada. At least 90 d before the experiment, the steers were fitted with 10-cm i.d. soft ruminal cannula (Bar Diamond, Parma, ID) as described by Tellier et al.
(2004). All animals were cared for in accordance with the
guidelines of the Canadian Council of Animal Care (1993).
Steers were offered barley straw (Lacombe, six-row) ad libitum along with five different concentrate feeding treatments as
follows: (1) low protein concentrate fed daily (Low-1), (2) lowprotein concentrate fed every second day at two times the daily
rate (Low-2), (3) high-protein concentrate fed daily (High-1),
(4) high-protein concentrate fed every second day at two times
the daily rate (High-2), (5) high-protein concentrate fed every
third day at three times the daily rate (High-3). The amount of
concentrate was calculated as 30% of the total as-fed intake of
the previous week. Steers were also provided with free access
to fresh water and trace-mineralized salt blocks. The straw was
chopped in a tub grinder (New Holland Model 390, Sperry,
New Holland, PA) to approximately 6 cm in length.
Composition of the concentrate mixtures and straw are summarized in Table 1. The straw contained 5.3% crude protein,
76.9% NDF, and 52.6% ADF. Straw was offered ad libitum in
such amounts as to maintain approximately a 10% weighback.
Concentrates were offered at 0900 on the days that they were
provided. All of the steers were allowed to consume the concentrate before the straw was offered (normally within 0.5 h).
On those days when animals were not fed concentrates, straw
was offered at 0900. Not all of the concentrate was consumed
in the time allotted on some occasions. In such cases, straw was
added on top of the concentrate.
Each period was designed to be 31 d in length, although
due to practicalities of scheduling facilities and equipment,
actual periods ranged from 26 to 35 d. There was a 14-d
adaptation period prior to sampling. Voluntary feed intake
measurements were obtained during days 15 to 20. During
this time, nylon bags were also incubated in the rumen and
faecal “grab” samples were obtained for calculation of
digestibility. Indirect calorimetry measurements were made
between days 21 and 31.
Animals were weighed before each period. Orts were
removed and weighed prior to feeding. Samples of straw,
concentrates, and orts were taken daily during day 15 to day
TELLIER ET AL. — CONCENTRATE SUPPLEMENTATION FOR CATTLE FED BARLEY STRAW
457
Table 1. Concentrate formulation and nutrient composition of straw and concentrates
Component
Straw
Low-protein
concentrate
High-protein
concentrate
97.8
2.0
0.2
64.4
32.0
1.4
2.0
0.2
14.1b
24.6a
18.68ab
15.1
18.92a
14.2
Ingredients (% as-fed)
Barley, dry rolled
Canola meal
Urea
Fortified salt
Vitamin ADE premix
Composition (DM basis)
Crude protein (%)
5.3c
Neutral detergent fibre (%)
76.9
Gross energy (MJ kg–1)
18.51b
Calculated digestible energyy (MJ kg–1)
z Standard error of the mean is based on five observations
yCalculated from NRC (1996) average values.
SEz
1.02
1.96
0.021
Probability
<0.01
0.03
per mean.
a–c Means not followed by the same letter differ (P < 0.05).
20 and composited for each animal. Feed, orts, and fecal
samples were dried in a forced-air oven (Despatch V Series,
Despatch Industries, Inc. Minnesota) at 60°C until a constant weight was achieved. Dried samples were ground to
pass a 1-mm screen prior to analysis.
In Situ Degradability in Nylon Bags
Measurements of ruminal disappearance of straw after 24,
48 and 72 h in situ incubations were conducted during days
15 to 20. Straw samples were ground (Thomas Mill Model
4, Philadelphia, PA) through a 2-mm screen and 2 to 3 g
were placed in 5 × 10 cm polyester mesh bags (20 to 30 mg
cm-2) with a pore size of 50 µm (ANKOM Technology
Corporation, Fairport, NY). After filling the bags were
sealed with an elastic band. Three bags were prepared for
each incubation time for each of the five steers. Since concentrate was fed each day with the Low-1 and High-1 treatments, there were three replicate bags for each sampling
time. However, with the Low-2 and High-2 diets, there were
only two replicate bags for day of concentrate feeding (24
and 72 h incubations) and only one replicate for the day concentrate was not fed (48 h bag). Only one bag was incubated for the different incubation times for the High-3
treatment. Samples were introduced in reverse sequence; the
72-h bags were placed in the rumen first, then the 48-h bags,
followed by the 24-h bags. After removal from the rumen,
nylon bags were frozen at –20°C until they could be washed
simultaneously in a conventional washing machine. The
bags were dried at 60°C to constant weight and weighed to
determine percent DM disappearance.
In Vivo Apparent Digestibility
Apparent digestibilities of DM, NDF, ADF, protein and
gross energy were determined by the lignin marker technique. Faecal samples were obtained either immediately
after voluntary defecation or by rectal grab sample six times
daily over the 6-d period. A 200-g sample was taken at each
sample time and composited on a daily basis. Faecal DM
produced daily (g) was calculated from the mean concentration of lignin in faeces as:
Fecal DM (g) = [lignin consumed (g)]/[faecal lignin
concentration (g g–1 DM)].
Heat Production
Indirect calorimetry measurements were conducted on
steers with their heads in hoods. Air was continuously withdrawn from hoods at rates set to maintain mean oxygen concentrations at 20%. Air flow was measured with a Foxboro
823 IFO integral flow orifice assembly with d/p cell transmitter (Invensys Systems, Inc., Foxboro, MA), pressure
with a Foxboro 821AL absolute pressure transmitter
(Invensys Systems, Inc., Foxboro, MA) and temperature and
relative humidity with a temperature/relative humidity
transmitter (General Eastern, Fairfield, CT). The respired air
was passed through Drierite (W. A Hamond Drierite Co. Lt.
Xenia, OH) to remove water vapour before passing though
an oxygen Analyzer (Servomex model 540A; Servomex
Inc., Sussex, England). Concentration of oxygen in room air
was also measured. Heat production was calculated as:
Heat production (kJ min–1) = –20.5 × (volume of expired
dry air under standard conditions, L min–1) × (fraction of
oxygen in exhaust air – fraction of oxygen in inlet air)
(McLean and Tobin 1990).
McLean andTobin (1990) point out that this approach gives
“reasonably accurate estimates of heat production (± 1.2%)”.
The calorimetry system was automated so data were collected for four animals each day over 22-h intervals. A computer
system with WorkBench™ software (v 2.0.2; Strawberry Tree
Inc., Sunnyvale Ca) controlled and monitored the system.
Measurements were averaged every 10 s during data collection
and written to a disk every 15 s. Information for air flow was
continuously monitored and stored for all four animals. Only
one oxygen analyzer was used; thus, exhaust air from each of
the four hoods as well as room air were sequentially passed
through the analyzer using solenoid-controlled values. With
each new source of air, the lines and oxygen analyzer were
flushed for 3 min before oxygen concentrations were determined over a 1-min interval. Oxygen concentrations in room
air and for each animal were thus recorded once every 20 min.
The system was calibrated by releasing a weighed amount of
nitrogen gas into the system (McLean and Tobin 1990).
0.05
0.56
0.02
0.205
0.045
1.779
7.11b
1.51
69.2b
7.90a
1.70
77.7a
7.95a
1.69
78.7a
a, b Means not followed by the same letter differ (P < 0.05).
zLow- or high-protein concentrate fed daily, every 2 d, or every 3 d.
yStandard error mean is based upon five animals per mean for individual
xProbability.
wBody weight.
treatments and ten animals per mean for contrasts.
7.66ab
1.63
75.8a
8.00a
1.70
78.8a
0.30
0.49
0.28
0.145
0.032
1.255
7.78
1.66
76.8
7.97
1.69
78.8
0.52
0.43
0.60
0.145
0.032
1.255
7.82
1.66
77.3
Total DM
kg
% BW
g kg BW-0.75
7.92
1.69
78.2
0.03
0.02
0.02
2.21ab 0.098
0.47ab 0.020
21.5b
0.913
2.48ab
0.53a
24.3ab
2.60a
0.55a
25.8a
2.10b
0.45b
20.7b
2.45ab
0.52a
24.3ab
0.04
0.04
0.03
0.070
0.014
0.646
2.29b
0.49b
22.5b
2.52a
0.54a
25.0a
0.03
0.02
0.03
0.070
0.014
0.646
2.27b
0.48b
22.5b
Concentrate DM
kg
% BW
g kg BW-0.75
2.53a
0.54a
25.0a
0.17
0.20
0.08
0.191
0.044
1.790
4.90
1.04
47.7
5.42
1.17
53.4
5.34
1.14
53.0
5.56
1.18
55.1
5.53
1.18
54.5
0.99
0.84
0.92
0.135
0.031
1.27
5.49
1.18
54.2
5.45
1.16
53.8
0.59
0.70
0.49
0.135
0.031
1.23
5.55
1.18
54.8
Straw DM
kg
% BWw
g kg BW-0.75
5.39
1.15
53.2
4.1
486
474
470
471
476
0.92
2.9
473
474
0.70
2.9
473
474
Steer wt (kg)
SEy
3d
2d
High protein
1d
2d
1d
Px
SEy
2d
1d
Individual treatments
Low protein
Frequency of feeding contrast for steers
fed concentrate daily or every 2 d
Px
SEy
High
Low
RESULTS
Feed Intake
Mean daily DM intakes of straw and concentrate and total
intake over the experimental period are outlined in Table 2.
Straw intake when the low-protein concentrates were fed
(5.55 kg d–1) was similar to straw intake when the high-protein concentrates were fed (5.39 kg d–1). Mean daily straw
intake when concentrate was fed daily was 5.45 kg in comparison with the intake of 5.49 kg in steers fed concentrate
on alternate days (P = 0.99). The amount of concentrate
offered was calculated as 30% of feed intake the previous
week, and was dependent on the amount of straw eaten.
Percentages of concentrate in the diet were 31, 27, 33, 31
and 31% for steers on the Low-1, Low-2, High-1, High-2
and High-3 treatments, respectively, which differed slightly
from the targeted 30%. Thus, in contrast with straw intakes,
there were differences (P < 0.05) in daily concentrate
intakes between treatments; steers fed the low-protein and
high-protein diets consumed 2.27 and 2.53 kg d–1, respectively. Also, steers fed straw daily and on alternate days
consumed 2.52 and 2.29 kg d–1, respectively. These
Table 2. Effect of dietary regimenz on mean daily dry matter intake over the experimental period
Statistical Analysis
Mean concentrate and straw intakes over the 6-d period for
each animal, ruminal straw DM disappearance, apparent
digestibilities and heat productions were analyzed as a 5 × 5
Latin Square design using the GLM procedure of SAS (SAS
Institute, Inc. 1988). Treatments (n = 5), animals (n = 5) and
periods (n = 5) were the main sources of variation. One animal (High-1 diet) was not included in analyses of straw DM
intake because of a brief illness during one period. Means
were separated using the Student-Newman-Keul’s test (SAS
Institute, Inc. 1988). Comparisons between both dietary protein content of concentrates and frequencies of feeding concentrates were examined using the GLM procedure of SAS
(SAS Institute, Inc. 1988) with only the Low-1, Low-2,
High-1, and High-2 treatments being considered in these
comparisons. Ruminal straw DM disappearances (24, 48
and 72 h) were examined by a repeated measures analysis
(SAS Institute, Inc. 1988), with time as the repeated measure. The effect of days when concentrate was fed versus
days when concentrate was not fed was determined within
each dietary treatment, with days (n = 2 or 3) and animals
(n = 5) as sources of variation.
Px
Chemical Analysis
Crude protein was determined on approximately 100-mg
samples of feed and faeces using a nitrogen analyzer (LECO
Model FP-428, St. Joseph, MI). Neutral detergent fibre was
determined according to the procedure of Van Soest et al.
(1991) without amylase or sodium sulphite. The Association
of Official Analytical Chemists (1997) procedure #973.18
was used for the determination of ADF. Fibre analysis was
conducted using an ANKOM200 Fiber Analyzer (ANKOM
Technology Corporation, Fairport, NY) with filter bags.
Lignin was measured with the 72% sulphuric acid procedure
of Goering and Van Soest (1970). Gross energy was measured with a Parr adiabatic bomb calorimeter (Parr
Instrument Co., Inc. Moline, IL).
0.12
CANADIAN JOURNAL OF ANIMAL SCIENCE
Protein concentration contrast for
steers fed daily or every 2 d
458
TELLIER ET AL. — CONCENTRATE SUPPLEMENTATION FOR CATTLE FED BARLEY STRAW
459
Fig. 1. Effect of days after concentrate feeding on voluntary straw DM intake of steers. Fed, Day-1 and Day-2 refer to day of concentrate
feeding, 1 d after concentrate fed and 2 d after concentrate fed, respectively. Vertical bars are pooled standard errors. Probabilities of treatment differences from repeated measures analyses were 0.74, 0.23 and 0.35 for Low-2, High-2 and High-3 dietary regimens, respectively.
unplanned for and unexpected differences were related to
differences in straw offered which was not consumed. Steers
fed the low-protein concentrate diets consumed 7.82 kg d–1
of total DM, which was similar (P = 0.52) to the 7.92 kg d–1
of those fed the high-protein concentrate diets. Intakes of
total DM were similar (P = 0.30) in steers fed concentrate
daily (7.97 kg d–1) and those fed concentrate on alternate
days (7.78 kg d–1).
The effect on straw intake of whether or not concentrate was
fed on a particular day is examined in Fig. 1. Straw intakes did
not differ between the days on which concentrate were fed and
not fed for the Low-2, High-2 and High-3 treatments.
Ruminal Disappearance of Barley Straw
Ruminal disappearances of straw at 24, 48, 72 h and the
means of these times are shown in Table 3. Mean disappearances of straw DM at 24, 48 and 72 h were 39.2, 50.3
and 55.2% (P < 0.01), respectively.
After 24 h incubation, straw disappearances were 37.0,
37.9, 42.1, 40.1, and 40.1% for Low-1, Low-2, High-1,
High-2, and High-3, respectively (P = 0.02). The difference
was due to protein content of the diet; feeding the high-protein concentrate compared to feeding the low-protein concentrate increased (P < 0.01) 24-h disappearance of straw by
10%. After 72 h, straw disappearance tended (P = 0.07) to
be lower when steers were fed the high-protein concentrate
every third day (High-3 diet) than when they were fed this
concentrate daily (High-1 diet). No other differences in
straw disappearance were detected between individual treatments due to protein level or frequency of feeding.
Day on which bags were placed in the rumen had no effect
on straw DM disappearance in any treatment. With the Low-2
diet DM disappearances on the day after concentrates were fed
in comparison with the day they were fed were 9, 5 and -3%
higher (P = 0.27) after 24, 48 and 72 h incubation, respectively. Corresponding values for the High-2 diet were 3, 0 and 3%
(P = 0.47). With the High-3 diet after 24 h of incubation, DM
disappearances were 5 and 2% higher on day 1 and day 2 after
feeding than they were on the day concentrate was fed, whereas corresponding values after 48 and 72 h incubation were 1
and –7% and –5 and –5% respectively (P = 0.53).
In Vivo Digestibility
Mean DM, NDF, ADF, protein and energy digestibilities
across all treatments were 56, 58, 45, 58 and 55%, respectively (Table 4). Digestibilities of DM, ADF, protein and
energy were 5, 8, 33, and 6% higher (P < 0.05), respectively, when steers were fed the high-protein concentrate rather
than the low-protein concentrate. Similarly, the digestible
energy contents of the high-protein diets were 7% higher
than that of the low-protein diets. There was no indication
that digestibility was affected by feeding concentrate less
frequently than once daily.
Digestibility estimates were also made for days on which
concentrates were fed and days when concentrates were not
fed using mean daily faecal lignin concentrations and the
mean DM intake over the 6-d period in the calculation. The
only difference detected was for crude protein digestibility
in steers fed concentrate once every 3 d (High-3 diet) where
the protein digestibility was 13% higher (P = 0.03) on the
460
CANADIAN JOURNAL OF ANIMAL SCIENCE
Table 3. Effect of dietary regimenz on ruminal disappearance (%) of barley straw
Protein concentration contrast for
steer fed daily or every 2 d
Frequency of feeding contrast for
steer fed daily or every 2 d
Individual treatmentsy
Low protein
High protein
Incubation time
Low
High
SEx
Pw
1d
2d
SEx
Pw
1d
2d
1d
24 h
48 h
72 h
37.5b
50.0
55.3
41.1a
50.5
55.2
0.65
0.68
0.39
<0.01
0.58
0.79
39.5
50.8
55.5
39.0
49.8
55.0
0.65
0.68
0.39
0.60
0.30
0.32
37.0b
50.1
55.0
37.9b
49.9
55.6
42.1a
51.5
56.0
2d
SEx
Pw
40.1ab 0.92
49.4
0.96
53.7
0.55
0.02
0.60
0.07
3d
40.1ab
49.6
54.3
zLow or high protein concentrate fed daily, every 2 d, or every 3 d.
yFor repeated measures analyses the SE was 1.10 and probabilities of treatment, time and treatment × time were 0.12, <0.01 and < 0.01, respectively.
xStandard error mean is based upon results from five animals per mean for individual treatments and ten animals per mean for contrasts.
wProbability.
a, b Means not followed by the same letter differ (P < 0.05).
Table 4. Effect of dietary regimenz on apparent digestibility, digestible energy intake and heat production of diets based upon barley straw
Protein concentration contrast for
steer fed daily or every 2 d
Frequency of feeding contrast for
steer fed daily or every 2 d
High
SEx
Pw
1d
57.5a
59.0
46.4a
64.8a
56.1a
0.76
0.77
0.56
1.54
0.80
0.04
0.11
<0.01
<0.01
0.02
Dietary digestible energy content
DEy (MJ kg–1)
9.8b 10.5a
0.15
Daily digestible energy intake
MJ
76.8
84.2
kJ kg BW-0.75
754
832
1.23
11.3
Item
Low
Apparent digestibility
54.7b
DMy (%)
NDFy (%)
56.7
ADFy (%)
42.9b
Protein (%)
48.7b
Energy (%)
53.0b
Daily heat production
MJ
58.5
kJ kg BW-0.75
574
59.4
590
0.802
8.59
Individual treatments
Low protein
High protein
2d
SEx
Pw
1d
2d
1d
2d
3d
SEx
Pw
55.9
58.0
43.9
57.0
54.4
56.1
57.6
45.1
55.6
54.5
0.76
0.77
0.56
1.54
0.80
0.91
0.93
0.21
0.29
0.96
54.4
56.6
41.9b
49.4b
52.7
55.0
56.8
43.9b
47.9b
53.3
57.8
59.6
46.4a
66.5a
56.6
57.2
58.5
46.4a
63.4a
55.7
58.7
59.4
47.5a
64.6a
57.3
1.08
1.08
0.80
2.18
1.14
0.08
0.31
<0.01
<0.01
0.07
0.02
10.1
10.1
0.15
0.92
9.8b
9.9b
10.6ab 10.4ab 10.7a
0.21
0.05
<0.01
<0.01
81.0
800
79.6
783
1.23
22.3
0.21
0.24
78.0ab 75.5b 84.8a 83.7ab 77.0ab 2.08
760ab 748ab 849a
819a
741b
17.6
0.03
0.01
0.03
0.06
59.7
582
0.20
0.14
0.17
0.16
60.2a 57.9b
594
570
0.802
8.59
57.4
566
60.9
609
58.3
574
57.8
558
1.27
12.7
zLow- or high-protein concentrate fed daily, every 2 d, or every 3 d.
yAbbreviations: DM = dry matter, NDF = neutral detergent fibre, ADF = acid detergent fibre, DE = digestible energy, and BW = body weight.
xStandard error mean is based upon results from five animals per mean for individual treatments and ten animals per mean for contrasts.
wProbability.
a, b Means not followed by the same letter differ (P < 0.05).
third day after concentrate feeding than the digestibility on
the day of concentrate feeding. Since there is a delay in
excretion of faecal material, it is difficult to relate this difference to the actual day of concentrate feeding.
Correlation coefficients were calculated between in vivo
digestibility of the concentrate-straw diets and in situ ruminal
disappearance of straw DM. Correlation coefficients between
DM digestibility (range 48 to 66%) and ruminal DM disappearances at 24, 48 and 72 h across all dietary regiments were
0.54, 0.51 and 0.45 (P < 0.05; n = 24), respectively.
Corresponding coefficients between NDF digestibility (range
48 to 68%) and ruminal DM disappearances were 0.58, 0.66
and 0.64 (P < 0.05).
Digestible energy contents of straw and percent digestibility
of straw energy were calculated using National Research
Council (1996) digestible energy values to estimate the
digestible energy content of low- and high-protein concentrates, subtracting the contribution of these concentrates from
the measured digestible energy value, and then assuming that
straw contributed the remaining digestible energy. Calculated
mean gross energy digestibilities for straw were 45.1, 40.6 and
48.3% for all diets, diets with low protein concentrate and diets
with high protein concentrates, respectively. Corresponding
digestible energy contents of straw were 8.4, 7.5 and 9.0 MJ
kg–1, which were higher than the 7.4 MJ kg–1 value given for
barley straw by National Research Council (1996). Ruminal
disappearances of straw DM were then used to predict straw
digestibility and digestible energy content (Table 5). Twentyfour, 48 and 72 h DM disappearances were all related (P <
0.05), or tended to be related (P < 0.1), with straw in vivo
digestibility and digestible energy content when individual
steer results obtained with all diets were compared. Similar
results were obtained when cattle were fed the high protein
concentrates. However, when low protein concentrates were
fed, only 72 h ruminal disappearances of straw were related (P
< 0.1) with in vivo digestion.
Heat Production
Daily intakes of digestible energy as well as heat production
of the steers are given in Table 4. Because of the increased
TELLIER ET AL. — CONCENTRATE SUPPLEMENTATION FOR CATTLE FED BARLEY STRAW
461
Table 5. Relationships between ruminal dry matter disappearance (%) of straw dry matter with apparent energy digestibility and digestible energy
content of straw
SE
R2
Probability
Both concentratesy
-1.07 + 1.172 (24 h disappearance)
-3.20 + 0.960 (48 h disappearance)
-0.15 + 0.821 (72 h disappearance)
6.30
6.57
6.84
0.25
0.18
0.12
0.01
0.02
0.06
Low protein concentratey
40.1 + 0.014 (24 h disappearance)
-4.00 +0.893 (48 h disappearance)
7.99 + 0.590 (72 h disappearance)
5.65
4.95
5.15
0.00
0.14
0.24
0.98
0.16
0.06
High protein concentratey
0.10 + 1.160 (24 h disappearance)
3.96 + 0.877 (48 h disappearance)
-13.3 + 1.121 (72 h disappearance)
6.13
6.16
5.96
0.21
0.20
0.25
0.06
0.06
0.04
Digestible energy content of strawy (MJ kg–1)
Both concentrates
-0.10 + 0.215 (24 h disappearance)
-0.57 + 0.178 (48 h disappearance)
0.05 + 0.151 (72 h disappearance)
1.20
1.24
1.30
0.23
0.17
0.11
0.01
0.02
0.07
Low protein concentrate
7.93 -0.010 (24 h disappearance)
-0.57 + 0.162 (48 h disappearance)
1.64 + 0.1067 (72 h disappearance)
1.08
0.96
1.00
0.00
0.11
0.27
0.94
0.18
0.04
High protein concentrate
0.07 + 0.218 (24 h disappearance)
0.68 + 0.164 (48 h disappearance)
-2.44 + 0.207 (72 h disappearance)
1.17
1.17
1.14
0.20
0.19
0.24
0.06
0.06
0.04
Equation
Digestibility of straw
energyz
(%)
zRange in gross energy digestibilities for straw in all diets, low-protein diets and high-protein diets were 29 to 59, 29 to 47 and 35 to 59%, respectively.
Corresponding ranges in digestible energy contents were 5.3 to 10.9, 5.3 to 8.8 and 6.4 to 10.9 MJ kg–1.
yNumbers of observations for both, low-protein and high-protein concentrates were 24, 10 and 14, respectively.
digestibility of the high-protein diets, digestible energy
intakes were higher (P < 0.01) in steers fed the high-protein
concentrate than in those fed the low-protein concentrate.
Dietary protein intake, however, had no influence on the
heat production of the steers. There were no differences in
digestible energy intake between steers fed concentrate
daily and those fed concentrates on alternate days; however,
heat production (kJ kg-0.75) was 4% higher (P= 0.06) in
steers fed concentrate daily.
Heat productions on days when concentrates were fed
were compared with heat production on days when concentrates were not fed within each dietary treatment (Fig. 2). No
differences were detected between days when concentrate
was fed and days when no concentrate was provided.
DISCUSSION
Voluntary Consumption of Straw-based Diets
The average protein content of six-row barley straw in
Alberta in 1984-1994 was 5.4% (Alberta Agriculture, Food
and Rural Development 1997), suggesting that the barley
straw used in this experiment was of average quality.
Voluntary consumption of straw averaged 1.18, 1.18,
1.14, 1.17, and 1.04% of body weight (Table 2) for animals
fed the Low-1, Low-2, High-1, High-2 and High-3 diets,
respectively. These straw intakes are similar to those of
Zorrilla-Rios et al. (1991) who measured intakes of untreated straw as 1.08, 1.14, and 1.17% of body weight when animals were supplemented with 0, 150, or 500 g d–1 soybean
meal, respectively. Okine et al. (1993) reported daily barley
straw intakes of 1.5% of body weight when barley strawbased and concentrate diets were fed. Beaty et al. (1994)
reported a daily intake of wheat straw of 1.4% when animals
had concentrate supplied daily and 1.18% when concentrates were supplied three times per week, the latter being
close to our intakes. All of these straw intakes were obtained
indoors under controlled conditions and are generally lower
than the barley straw intake of 1.5% of body weight of cows
measured by Weisenburger et al. (1977) in an outdoor winter feeding trial. Mathison et al. (1981), however, reported
barley straw intakes of 1.3% of body weight in an outdoor
winter feeding trial with cows.
It is well accepted that protein deficiencies can decrease
feed intake (National Research Council 1996). In this study,
however, protein supplementation did not increase voluntary intake of straw. This was surprising since the intake of
rumen degradable protein was below requirements (Tellier
et al. 2004) and rate of disappearance of straw in the rumen
462
CANADIAN JOURNAL OF ANIMAL SCIENCE
Fig. 2. Effect of days after concentrate feeding on heat production of steers. Fed, Day-1 and Day-2 refer to day of concentrate feeding, 1 d
after concentrate fed and 2 d after concentrate fed, respectively. Vertical bars are pooled standard errors. Probabilities of treatment differences from repeated measures analyses were 0.13, 0.86 and 0.34 for Low-2, High-2 and High-3 dietary regimens, respectively.
was reduced with the low-protein diet. With only five animals, however, we would not have been able to detect a difference in voluntary intake of less than 6% because the
statistical power of our experiment was limited.
Supplemental protein did not increase straw intake in the
study of Weisenburger and Mathison (1977) but in many
other studies it has (Mathison et al. 1981; Sunvold et al.
1991; Beaty et al. 1994).
Neither straw intake nor total intake was affected when
steers were fed concentrate less frequently than once daily,
although straw intake was numerically 8% less when the
high-protein concentrate was provided every third day than
when it was provided daily (Table 2). Supplementing lowquality forage-based diets less than once daily has been
shown to have a variable effect on intake. Hunt et al. (1989)
reported similar intakes in steers fed grass hay (6.6% crude
protein) and provided with a cottonseed supplement every 12,
24, or 48 h. Chase and Hibberd (1989) did not detect a difference in intake between cows fed low-quality grass hay (5%
crude protein) and supplemented either a low level (1.4 kg
daily equivalent) or a high level (2.0 kg daily equivalent) of
corn daily or on alternate days. In contrast, in the study of
Beaty et al. (1994), intake of wheat straw fell (P < 0.01) from
1.42% for animals supplemented daily to 1.18% body weight
for animals fed three times per week with a soybean
meal/sorghum grain supplement. Collins and Pritchard (1992)
reported an 8% decrease in intake with alternate day feeding
of protein supplements but also concluded that DM intake
was variable in response to protein source and frequency.
The observation that straw intake did not differ between
days when concentrate was fed and days when concentrate
was not fed (Fig. 1) is of interest. It can be concluded that
steers did not change their intake behaviour in anticipation
of changes in availability of concentrate. Also, similar straw
intakes across days demonstrated that the steers were able to
physiologically adjust to the reduced nutrient intake on days
when concentrate was not fed, probably because the long
residence time in the rumen tends to even out nutrient supply to the animal over time.
In Situ Disappearance of Straw
The polyester bags contained 20 to 30 mg of sample cm-2 of
bag surface. This relatively high weight to surface area ratio
was used by 16% of researchers in the summary of Vanzant
et al. (1998). This is higher than the recommended value of
10 mg cm-2, but according to Vanzant et al. (1998), the
effect of weight per surface area is reduced when slowly
degrading forages such as straw are used. The use of a 2-mm
screen for grinding and a 50-µm pore size are consistent
with recommendations of Vanzant et al. (1998).
There was a 10% increase (P < 0.01) in ruminal disappearance of straw after 24 h incubation when the high-protein concentrates were fed in comparison to the low-protein
concentrates. Such a difference was not apparent at either 48
or 72 h, which suggests that the rate, rather than the extent
of disappearance was influenced by dietary protein. Hunt et
al. (1989) measured an increase in ruminal degradability of
forage with protein supplementation.
TELLIER ET AL. — CONCENTRATE SUPPLEMENTATION FOR CATTLE FED BARLEY STRAW
Frequency of provision of concentrate did not influence 24,
48, or 72 h ruminal disappearance of straw (Table 1). These
results are consistent with those of Hunt et al. (1989) who
found that in situ fibre degradability of grass hay was not
affected by feeding cottonseed meal every 12, 24, or 48 h.
Digestibility of Diets
The mean apparent DM digestibility was 57% and the mean
digestible energy content of the diets was 10.3 MJ kg–1.
According to National Research Council (1996) information
average barley straw and low-protein concentrate contained
7.4 and 15.1 MJ kg–1 digestible energy, respectively. Using
this information the calculated energy content of the lowprotein diet was 9.7 MJ kg–1, which was similar to the 9.8
MJ kg–1 actually obtained. Using the formula to calculate
digestible crude protein from dietary crude protein provided
by National Research Council (1984), the low (7.9% crude
protein) and high protein diets (11.5% protein), should have
contained 4.3 and 7.4% digestible protein, which corresponds to expected percentage protein digestibilities of 54
and 65%. The measured digestibilities of protein for the low
and high diets were 49 and 65%, respectively. On the basis
of these estimates, we have confidence that the digestibilities obtained with the lignin marker were quite accurate.
Crude protein digestibilities were higher with the high-protein diet (Table 4). This would be expected in light of the higher rate of ruminal disappearance with this diet. In addition,
digestibilities of DM, ADF and energy were improved (P <
0.05) with the high-protein diets. The improvement in
digestibility is consistent with the 10% increase in ruminal
degradability of straw which we observed at 24 h when straw
was incubated in situ in steers consuming the high-protein diets
(Table 3). Our results therefore confirm those of researchers
such as Ortigues et al. (1990), Beaty et al. (1994) and Fike et al.
(1995) who measured improvements in the digestibility of
straw associated with protein supplementation.
Frequency of feeding concentrate had no influence on the
digestibility of DM, NDF, ADF, and energy (Table 4), a
result which may be explained by ruminal ammonia concentrations (Tellier et al. 2004). This result is similar to that
obtained by Coleman and Wyatt (1982) and Collins and
Pritchard (1992). Chase and Hibberd (1989) concluded that
feeding corn on alternate days tended (P < 0.23) to reduce
digestibilities of grass hay diets. In contrast, Beaty et al.
(1994) found that decreasing feeding frequency from seven
times per week to three times per week increased NDF
digestibility 6.5% (51.1 vs. 54.4%). Bohnert et al. (2002)
noted that protein supplements fed as infrequently as once
every 6 d improved DM digestibility of a low- quality forage.
Significant relationships between ruminal DM disappearances and in vivo digestibilities were present (Table 5). Such
relationships have been noted previously (Chenost
et al. 1970; Aerts et al. 1977; von Keyserlingk and Mathison
1989). In our study, standard errors of prediction were high
and R2 values were relatively low. This is because our results
were based upon measurements from individual animals fed
the same diet whereas literature results generally are based
upon dietary means of different diets obtained with at least
four animals.
463
Normally in situ information is used to determine relative
differences within the same experiment. Comparing our
data with data of von Keyserlingk and Mathison (1989) suggests, however, that equations relating in situ ruminal disappearances of straw with in vivo digestibility may give
similar estimates of in vivo digestibilities across experiments. Using the equations of von Keyserlingk and
Mathison (1989), predicted apparent digestibilities of straw
DM were 51, 50.7 and 50%, at 24, 48 and 72 h, respectively. These estimated digestibilities compare favourably with
the 48.3% gross energy digestibility of straw obtained for
the high-protein diet using lignin as a marker and average
values for the digestible energy content of concentrates.
Heat Production
Differences in heat production of steers could not be detected between individual treatments, nor were heat productions
different when animals were fed concentrates with differing
protein concentrations (Table 4). The 4% reduction (P = 0.06)
in heat production (kJ kg-0.75) in steers fed on alternate days
has not, to our knowledge, been reported previously. The
corresponding non-significant 2% reduction in DM and
digestible energy intake of the steers fed concentrate on
alternate days would not explain the difference in heat production since digestible energy intakes were slightly above
the maintenance level of feeding and a significant portion of
this 2% difference in digestible energy intake would have
been deposited in steer tissue rather than appearing as heat.
The reduction in heat production in steers fed concentrate
on alternate days indicates either that these animals were
more efficient in utilizing dietary digestible energy, or that
energy losses in urine and methane emissions were
increased. Urinary energy losses were not measured. Also,
the methane analyzer was not working properly so we did
not obtain useful measurements of methane emissions in
this experiment. We are unaware of any data in which urinary energy losses have been measured in steers fed concentrates on alternate days. Data of Sutton et al. (1986)
indicate that methane production should be reduced when
animals are fed less frequently. The probability of reduced
methane emissions with alternate day feeding is supported
by the observation that ruminal acetate-to-propionate ratios
were lower in steers fed concentrates on alternate days
(Tellier et al. 2004). Reduced acetate-to-propionate ratios
are normally associated with reduced methane emissions
(Mathison et al.1998). Further, since in total, urinary and
methane energy losses generally only represent 18% of
digestible energy intakes (National Research Council 1996),
it is doubtful if changes in these parameters would be sufficient to account for the 4% reduction in heat production in
steers fed concentrate on alternate days.
There are various mechanisms by which heat production
could be reduced in steers fed concentrate less frequently
than once daily. Maintenance requirements are reduced during periods of feed restriction (National Research Council
1996). Support for this alternative as the main mechanism
for reduced heat production in these steers is weakened
because of the short periods of energy restriction (1 or 2 d).
Moreover there is evidence for decreased rather than
464
CANADIAN JOURNAL OF ANIMAL SCIENCE
increased efficiency of energy use with less frequent provision of nutrients because of increased energy costs associated with cyclical energy storage. In this regard, Hyltander et
al. (1993) found a more pronounced response in heat production, and hence reduced energy assimilation, when
humans were given six bolus-based intermittent infusions of
60 min duration over a 24-h period rather than having nutrients continuously infused. Another alternative for consideration is that reduced frequency of feeding concentrates
influenced heat production through a reduction in energy
costs of eating and rumination. Such costs are substantial
(Ferrell 1988). No measurements of eating and ruminating
times were made in this experiment. Significant relationships were, however, found between heat production and
ruminal acetic:propionic acid rations and branched-chain
fatty acids, which are discussed in a companion report
(Tellier et al. 2004).
Weight changes should be impacted if cattle are more efficient when concentrates are fed less frequently. Although
McIlvain and Shoop (1962), Brandyberry et al. (1992) and
Huston et al. (1999) concluded that provision of supplements
less frequently than once daily had no influence on weight
changes, Collins and Pritchard (1992) and Beaty et al. (1994)
measured a detrimental effect on weight changes. Intakes of
metabolizable energy were not similar between treatment
groups, however; thus it is difficult to determine energetic efficiencies from these weight change experiments.
CONCLUSIONS AND IMPLICATIONS
Our study supports earlier research where it was found that
straw DM intake was not influenced by feeding concentrates
less frequently than once daily. The observation that straw
intake did not differ between the days when straw was or
was not fed suggests that more than one day is required for
behavioural and physiological adaptations to occur in voluntary intake. In support of much of the previous research,
frequency of provision of concentrates had no effect on
digestibilities of the diets, although digestibilities were
increased with protein supplementation. The reduced heat
production of the steers fed concentrate on alternate days
suggests that these animals may have been more energetically efficient, but further studies are required to confirm
this observation. Although no significant differences were
obtained, there were indications that voluntary intake may
be reduced when concentrates are fed only every third day.
It was concluded that concentrate may be fed every second
day without any negative impact on intake and digestibility,
with the possible benefit of a reduction in energy lost as
heat. More research, however, is required to study the feasibility of feeding concentrate every third day.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge S. Melnyk and the staff
at the Laird McElroy Environmental and Metabolism
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project. Financial Assistance was provided by Alberta
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