scispace - formally typeset

Journal ArticleDOI

Relationships between morphological and chemical characteristics of perennial ryegrass varieties and intake by sheep under continuous stocking management

01 Dec 2004-Grass and Forage Science (Wiley)-Vol. 59, Iss: 4, pp 389-398

Abstract: Plots of five intermediate-heading varieties of perennial ryegrass (Lolium perenne L.) [AberDove, Belramo and Glen (diploid); Twins (tetraploid); and AberExcel (tetraploid hybrid)] were continuously stocked with sheep to maintain a target sward surface height of 4050 mm. Daily dry matter (DM) intake was significantly different (F-value = 0.032) between the varieties, with the tetraploid hybrid AberExcel having the highest values for daily DM intake and intake rate during eating. Amongst the diploid varieties, intake rate tended to be higher for sheep grazing Glen. The varieties comprised a wide range in potential growth habit, from the relatively prostrate, highly tillered Glen to the more-erect AberExcel and there were differences between them in the vertical distribution of leaves within the sward canopy. The leaves of AberExcel weighed 3.6 mg DM cm(-2) leaf area in contrast to the other varieties (4.3-5.3 mg DM cm(-2) leaf area) resulting in a high leaf area index (LAI) in relation to the green leaf mass. Intake rate was not significantly correlated with extended tiller and sheath tube lengths, partition of herbage mass, number of tillers per square metre or LAI. However, canonical variates analysis showed that there were significant differences between the varieties for the morphological and chemical factors examined. Other factors also need to be explored to explain these differences in ingestive behaviour in order to identify plant traits that are correlated with herbage intake rate. These are needed for varieties destined for grazing use, both during the breeding programme and their subsequent evaluation.
Topics: Lolium perenne (51%)

Content maybe subject to copyright    Report

Relationships between morphological and chemical
characteristics of perennial ryegrass varieties and
intake by sheep under continuous stocking
management
R. J. Orr, J. E. Cook, R. A. Champion and A. J. Rook
Institute of Grassland and Environmental Research, North Wyke, Okehampton, UK
Abstract
Plots of five intermediate-heading varieties of perennial
ryegrass (Lolium perenne L.) [AberDove, Belramo and
Glen (diploid); Twins (tetraploid); and AberExcel
(tetraploid hybrid)] were continuously stocked with
sheep to maintain a target sward surface height of 40–
50 mm. Daily dry matter (DM) intake was significantly
different (F-value ¼ 0Æ032) between the varieties, with
the tetraploid hybrid AberExcel having the highest
values for daily DM intake and intake rate during
eating. Amongst the diploid varieties, intake rate tended
to be higher for sheep grazing Glen. The varieties
comprised a wide range in potential growth habit, from
the relatively prostrate, highly tillered Glen to the
more-erect AberExcel and there were differences
between them in the vertical distribution of leaves
within the sward canopy. The leaves of AberExcel
weighed 3Æ6mgDMcm
)2
leaf area in contrast to the
other varieties (4Æ 3–5Æ3mgDMcm
)2
leaf area) result-
ing in a high leaf area index (LAI) in relation to the
green leaf mass. Intake rate was not significantly
correlated with extended tiller and sheath tube lengths,
partition of herbage mass, number of tillers per square
metre or LAI. However, canonical variates analysis
showed that there were significant differences between
the varieties for the morphological and chemical factors
examined. Other factors also need to be explored to
explain these differences in ingestive behaviour in order
to identify plant traits that are correlated with herbage
intake rate. These are needed for varieties destined for
grazing use, both during the breeding programme and
their subsequent evaluation.
Keywords: perennial ryegrass, intake, sward morphol-
ogy, continuous stocking, sheep
Introduction
Orr et al. (2003) identified marked differences between
perennial ryegrass (Lolium perenne L.) varieties in their
intake characteristics when continuously stocked with
sheep in a 2-year experiment. Compared with the mean
in each year, the ranges in values for daily dry matter
(DM) intake were proportionately 0Æ81–1Æ24 in 1998
and 0Æ80–1Æ19 in 1999. Intake attributes are not assessed
by UK national testing procedures (Ministry of Agri-
culture, Fisheries and Food, 1998) for those varieties
featured on the Recommended Lists (National Institute
of Agricultural Botany, 1998). Evaluation procedures
consider yield under simulated grazing management
(measured by frequent cutting), mid-season digestibil-
ity, ground cover, winter hardiness and disease resist-
ance. Ideally, there is a need for evaluation under
grazing but Hazard et al. (1998) suggested that the use
of animal trials in routine evaluation of grass cultivars
under grazing was expensive and time-consuming.
They indicated a need to identify morphological traits
of cultivars that enhance animal production under
grazing (Hodgson, 1985; Baumont et al., 2000) which
could be used to evaluate grass cultivars in breeding
programmes. Here it is explored whether the differ-
ences in grass intake measured by Orr et al. (2003) were
related to morphological and chemical characteristics
(Diaz et al., 2001; Liu et al., 2002) that could be targeted
for those varieties destined for use under grazing
management (Stone, 1994).
Materials and methods
Sward treatments
The experimental grazing treatments were imposed
between 8 March and 9 June 2000 at the Institute of
Correspondence to: R. J. Orr, Institute of Grassland and
Environmental Research, North Wyke, Okehampton,
Devon EX20 2SB, UK.
E-mail: robert.orr@bbsrc.ac.uk
Received 29 May 2003; revised 25 January 2004
2004 Blackwell Publishing Ltd. Grass and Forage Science, 59, 389–398
389

Grassland and Environmental Research (IGER), North
Wyke (5046¢N, 356¢W).
Five intermediate-heading varieties of perennial rye-
grass were chosen from the fifteen that had been sown
in September 1997 and grazed by sheep in 1998 and
1999 (Orr et al., 2003) to give a wide range in intake
characteristics. The varieties chosen were either diploid
(AberDove, Belramo and Glen), tetraploid (Twins) or
tetraploid hybrid (Lolium · boucheanum Kunth) (Aber-
Excel). Fertilizer supplying 40 kg N ha
)1
,20kg
P
2
O
5
ha
)1
and 20 kg K
2
Oha
)1
was applied to the
swards on 30 March 2000, followed by an application of
40 kg N ha
)1
on 5 May 2000.
Animals and grazing management
Core groups of three non-pregnant, non-lactating (dry)
Welsh Mountain ewes [live weight (s.e. of mean), 33
(0Æ2) kg] were continuously stocked on the same five
replicate paddocks (0Æ1 ha) of each grass variety that
were grazed in 1998 and 1999 (i.e. the third grazing
year for each paddock). Each core group comprised one
ewe aged 2 years and two ewes aged 3 years.
A target sward surface height (SSH) of 40–50 mm
was maintained on each of the twenty-five paddocks
using a put-and-take system, with additional ewes
added to or removed from the paddocks as required.
Measurements
Morphological measurements
Sward surface height was measured each week using a
sward stick (Barthram, 1986), with twenty-five contacts
per paddock. Herbage measurements were made on
each of the five blocks in succession on 23 and 24 May;
24 and 25 May; 30 and 31 May; 31 May and 1 June; 1
and 2 June. Herbage mass, composition and the
number of tillers per square metre were measured
within 50 cm · 25 cm quadrats. The herbage was cut to
ground level using scalpels and sub-samples of grass
were separated into live leaves, live vegetative and
reproductive stems, and dead material. Reproductive
tillers in the subsample were identified on the basis of
internode elongation and the numbers of both repro-
ductive and vegetative tillers in the subsample were
counted. The dry weight (oven-drying at 80C for 20 h)
of the components and the number of tillers were
calculated from the contribution of their weight to the
total weight of the respective subsamples and the total
sample weight.
Extended tiller lengths (ETL) and sheath tube lengths
of the youngest and oldest fully expanded live leaves
were measured on all the tillers in each subsample
(approximately sixty tillers per paddock). LAI (leaf area
per unit ground area) was measured by passing leaves
from these tillers through a planimeter before they
were dried, which allowed dry weights per unit leaf
area to be calculated.
The vertical distribution of leaves within the swards
was estimated using an inclined point quadrat (IPQ)
as described by Grant (1981). This device works by
passing a needle from the surface of the sward, at an
angle of 32Æ5, down to the soil level. This angle was
determined (Warren Wilson, 1963) from consideration
of the grass foliage angle (inclination of foliage to the
horizontal). Turves (10 cm · 20 cm) were cut, taken
indoors and placed on a bench where the measure-
ments were made. Twenty-five descents were made
on each variety and each contact with leaves was
recorded from a graduated scale so that the height
above ground level could be calculated by trigonom-
etry.
Daily intake, eating time, intake rate and ruminating time
Grass intake was measured using a modification of the
n-alkane method of Dove and Mayes (1991). The three
core sheep in each paddock were dosed with Captec
TM
n-alkane slow-release devices (FERNZ, Manurewa,
Auckland, New Zealand). Following an initial acclima-
tization period, the boluses were designed to release
C
32
-alkane (dotriacontane) within the rumen at a
constant rate between days 8 and 16 after dosing. Eight
days after dosing, any spare ewes were removed for
48 h and marked areas (15 m · 2 m) within each
paddock were cleared of all faeces. This was done on
23, 25 and 31 May, 1 and 7 June for the five replicate
blocks in succession. Faeces samples were collected,
from within the cleared areas, 24 and 48 h after
clearing. This procedure ensured that only samples
from dosed animals were collected.
Herbage samples (snipped samples), designed to be
representative of the material eaten, were cut with
scissors from the grazed horizon in the top third of the
sward (Orr et al., 1997) at the same time as the initial
faeces clearance. Mean daily DM intake by the group
was calculated from the assayed release rate of C
32
-
alkane (44Æ9mgd
)1
) and the concentrations of C
32
-
and C
33
-alkane (tritriacontane) in herbage and faeces
(Dove and Mayes, 1991).
Jaw movements were recorded over 24 h for one
core ewe on each of the twenty-five paddocks, using
automatic behaviour recorders (Rutter et al., 1997).
Recordings were subsequently analysed using the
GRAZEGRAZE
TM
software (Rutter, 2000) to distinguish periods
of eating, ruminating and idling and thus allow the
calculation of eating time (Gibb, 1998). Intake rate
during eating was calculated from intake (g DM d
)1
)
and eating time (min d
)1
). Rumination chews were
390
R. J. Orr et al.
2004 Blackwell Publishing Ltd, Grass and Forage Science, 59, 389–398

identified, and the number of chews per minute and per
bolus were calculated.
Data for eating time and ruminating time included
pauses of <3 s between successive jaw movements (i.e.
the minimum inter-bout interval was 3 s) and an eating
bout and a ruminating bout each contained at least ten
jaw movements. Jaw movements that did not satisfy
these criteria were broadly designated as ‘other activ-
ities’ e.g. drinking, grooming, vocalization, etc. The
patterns of meals throughout the day were examined
by joining eating bouts with a minimum inter-meal
interval of 6 min (Penning et al., 1993) to create grazing
bouts as defined by Gibb (1998), which included intra-
meal intervals of 3 s–6 min duration. Individual
rumination bouts associated with the eructation of
each bolus were joined using a minimum inter-rumin-
ation bout interval of 20 s.
Chemical analyses
The snipped grass samples were analysed for digestibil-
ity of organic matter in the DM (DOMD in vitro; Jones
and Haywood, 1975), for nitrogen (N) concentration by
the Kjeldahl method, with copper sulphate as a catalyst,
using a Tecator 1030 auto analyser (Tecator, 1987) and
for water-soluble carbohydrate (WSC) concentration
(Thomas, 1977).
Statistical analysis
The group of three core ewes was used as the experi-
mental unit for statistical analysis of animal variables
(i.e. all the analyses were based on n ¼ 25, with sixteen
residual d.f. as the five treatments were allocated to five
blocks) as the behaviour and performance of the
individuals were not regarded as independent (Rook
and Penning, 1991). Data were analysed by one-way
analysis of variance with randomised blocks using
GENSTAT (GENSTAT, 1987). In addition to the overall
effect of variety, the effects of ploidy (diploid vs.
tetraploid) and hybridisation (tetraploid vs. tetraploid
hybrid) were also examined using orthogonal contrasts
(see Tables 1–3). Correlation analyses between inges-
tive behaviour and plant factors were performed using
values for individual plots (i.e. n ¼ 25). Canonical
variates analysis, using the CVA directive in
GENSTATGENSTAT
,
was used to find linear combinations of the original
variables that maximized the ratio of between-variety
to within-variety variation, thereby giving functions of
the original variables that could be used to discriminate
between the varieties. The CVAPLOT procedure was
then used to plot the mean scores of the first two latent
vectors of the canonical variates analysis and to display
95% confidence limits. Dendrograms were plotted
of levels of similarity between the varieties using
Table 1 Grass morphology and chemical composition for diploid and tetraploid perennial ryegrass varieties continuously stocked
with sheep.
Diploid Tetraploid
s.e.d.
F probability
AberDove Belramo Glen AberExcel† Twins Overall Ploidy Hybridisation
Morphological factors
SSH (mm) 46Æ748Æ945Æ245Æ145Æ42Æ62 0Æ579 0Æ332 0Æ928
ETL (mm) 54Æ350Æ850Æ461Æ652Æ04Æ71 0Æ171 0Æ129 0Æ062
ETL:SSH ratio 1Æ16 1Æ04 1Æ12 1Æ37 1Æ15 0Æ104 0Æ169 0Æ126 0Æ111
Sheath tube length (mm)
Oldest fully expanded live leaf 14Æ715Æ213Æ816Æ613Æ32Æ32 0Æ647 0Æ827 0Æ171
Youngest fully expanded live leaf 23Æ825Æ020Æ728Æ420Æ23Æ61 0Æ195 0Æ619 0Æ037
Leaf mass (kg DM ha
)1
) 1321 905 1307 1216 1242 176Æ40Æ169 0Æ655 0Æ882
Pseudostem (kg DM ha
)1
) 1289 1151 1046 1109 872 156Æ70Æ159 0Æ109 0Æ149
Leaf:pseudostem ratio 1Æ05 0Æ78 1Æ30 1Æ15 1Æ41 0Æ181 0Æ027 0Æ056 0Æ163
Tillers (in thousands m
)2
)39Æ731Æ143Æ231Æ125Æ77Æ18 0Æ149 0Æ055 0Æ461
Leaf weight (mg DM cm
)2
leaf area) 4Æ44Æ64Æ33Æ65Æ30Æ65 0Æ172 0Æ950 0Æ017
Leaf area index 3Æ12Æ03Æ23Æ52Æ60Æ73 0Æ292 0Æ521 0Æ217
Chemical factors
WSC (g kg
)1
DM) 213 177 193 186 249 19Æ00Æ012 0Æ077 0Æ004
DOMD (g DOM kg
)1
DM) 735 711 720 719 745 7Æ40Æ002 0Æ047 0Æ003
Nitrogen (g kg
)1
DM) 40 40 38 44 37 2Æ60Æ138 0 Æ 681 0Æ017
†Hybrid.
DM, dry matter; DOMD, organic matter in the DM; ETL, Extended tiller length; SSH, Sward surface height; WSC, water-soluble
carbohydrate.
Intake of perennial ryegrass varieties by sheep
391
2004 Blackwell Publishing Ltd, Grass and Forage Science, 59, 389–398

hierarchical clustering procedures in
GENSTATGENSTAT
. The IPQ
data were analysed by fitting asymmetrical s-shaped
curves for each paddock and from analysis of variance
on the inflection points and upper asymptotes.
Results
Morphological traits
Mean sward surface height (Table 1) when the meas-
urements of intake were made was within the target
range of 40–50 mm for all five varieties. Within the
tetraploid varieties, extended tiller length tended to be
greater (P ¼ 0Æ062) for AberExcel (hybrid) than Twins.
The ratio of extended tiller length to sward surface
height, along with sheath tube lengths of the oldest and
youngest fully expanded live leaves, tended to be
greater for AberExcel than the other varieties but these
trends were not significant between the five varieties.
Within the tetraploid varieties, the length of the sheath
tube of the youngest fully expanded leaf was greater
(P ¼ 0Æ037) for AberExcel than Twins (28Æ4 mm vs.
20Æ2 mm) at the same sward surface height.
The mean number of IPQ leaf contacts in each
horizon is shown in Figure 1. Above 40 mm from the
root–shoot interface, the variety AberExcel, in partic-
ular, together with the Glen and AberDove varieties,
had more contacts than the Twins and Belramo variety.
The variety Glen tended to have most leaf contacts in
total and the variety Belramo had the least, but these
effects were not significant.
Leaf and pseudostem masses, and the number of grass
tillers per square metre, were not significantly different
between the five varieties, although Belramo had a
much lower green leaf mass (Table 1). Leaf:pseudostem
ratios were significantly different (P ¼ 0Æ027) between
the five varieties and tended to be higher (P ¼ 0Æ056)
for the tetraploid than the diploid varieties.
The swards were all very highly tillered, particularly
the diploid variety Glen, as a result of the continuous
stocking management with sheep. Comparing the
effects of ploidy, the diploid varieties tended (P ¼
0Æ055) to have greater numbers of tillers per square
metre than the tetraploid varieties. Within the tetrap-
loid varieties, the leaves of AberExcel had significantly
lower (P ¼ 0Æ017) weights per unit leaf area than Twins
(3Æ6mgDMcm
)2
vs. 5Æ3mgDMcm
)2
). This resulted
in the variety AberExcel tending to have a high LAI in
relation to the green leaf mass.
Chemical composition
There were significant differences between varieties
(Table 1) in water-soluble carbohydrate concentration
(P ¼ 0Æ012) and DOMD value (P ¼ 0Æ002) but not in N
concentration. The tetraploid varieties had significantly
higher DOMD values (P ¼ 0Æ047) than the diploids and,
within the tetraploid varieties, Twins had a significantly
Table 2 Daily intake, eating time and intake rate for sheep continuously stocked on diploid and tetraploid ryegrass varieties.
Diploid Tetraploid
s.e.d.
F probability
AberDove Belramo Glen AberExcel† Twins Overall Ploidy Hybridisation
Daily intake (g DM ewe
)1
) 603 765 734 904 616 93Æ40Æ032 0Æ345 0Æ007
Eating time [min (24 h)
)1
) 616 707 642 664 628 61Æ60Æ619 0Æ818 0Æ576
Intake rate (mg DM min
)1
eating) 978 1089 1165 1390 1004 188Æ80Æ239 0Æ 340 0Æ057
Number of meals (24h
)1
)7Æ45Æ87Æ27Æ67Æ21Æ60 0Æ810 0Æ571 0Æ806
Meal duration (h) 1Æ73 2Æ43 1Æ67 1Æ85 1Æ69 0Æ484 0Æ503 0Æ592 0Æ747
†Hybrid.
Table 3 Ruminating time, number of boluses per 24 h, chews per 24 h, chews per minute and chews per bolus for sheep
continuously stocked on diploid and tetraploid ryegrass varieties.
Diploid Tetraploid
s.e.d.
F probability
AberDove Belramo Glen AberExcel† Twins Overall Ploidy Hybridisation
Ruminating time (min 24 h
)1
) 332 387 304 350 278 47Æ70Æ242 0Æ397 0Æ154
Number of boluses (24 h
)1
) 451 489 418 470 422 54Æ60Æ650 0Æ844 0Æ390
Ruminating chews (24 h
)1
) 26047 30937 24561 29536 21348 5412Æ 40Æ429 0Æ625 0Æ150
Ruminating chews (min
)1
)77Æ179Æ680Æ083Æ474Æ86Æ74 0Æ764 0Æ971 0Æ221
Ruminating chews (bolus
)1
)56Æ763Æ657Æ962Æ548Æ97Æ33 0Æ322 0Æ443 0Æ082
†Hybrid.
392
R. J. Orr et al.
2004 Blackwell Publishing Ltd, Grass and Forage Science, 59, 389–398

higher DOMD value (P ¼ 0Æ003), higher WSC concen-
tration (P ¼ 0Æ004) and lower N concentration (P ¼
0Æ017) than AberExcel.
Daily intake, eating time and intake rate
Daily DM intake (Table 2) was significantly different
(P ¼ 0Æ032) between the varieties. Within the tetraploid
varieties daily intake was higher (P ¼ 0Æ007) for ewes
grazing AberExcel than for those grazing Twins, and
intake rate also tended to be higher (P ¼ 0Æ057).
Eating time was not significantly different between the
five varieties [mean: 652 min (24 h
)1
)]. Examination
of the patterns of meals for individual ewes made on
each of the five replicate paddocks for each variety
indicated that most of the grazing occurred between
sunrise (05:00 h) and sunset (21:45 h). Whilst the
number of meals per day tended to be lower on the
variety Belramo and the meal duration tended to be
greater than on the other varieties, these were not
significant (Table 2).
Ruminating time, boluses and chews
The variety Belramo tended to have the highest values
for all the aspects of rumination behaviour (except
rumination chewing rate) shown in Table 3 and the
variety Twins had the lowest values (except for the
number of boluses per 24 h, for which the value was
close to that for the variety Glen which was the lowest),
but these differences were not significant. The period
following sunset (and the cessation of the evening
meal) until approximately 09:00 h was characterized by
alternating bouts of rumination and rest on all five
varieties. There was some further processing of ingested
grass interspersed between eating bouts, particularly in
the late morning/early afternoon period, but the period
before sunset (approximately 4 h) was mainly occupied
by eating.
Canonical variates analysis
The canonical variates analysis for the plant factors
are summarized in Figure 2a where the mean scores
for latent vector 1 and latent vector 2 are plotted,
along with the 95% confidence limits. The plant
factors included were those listed in Table 1. The
variation accounted for by latent vectors 1, 2 and 3
was 62Æ7, 28Æ5 and 5Æ6% respectively. The analysis
clearly separated the tetraploid varieties from the
diploid varieties. AberExcel differed from the other
varieties in latent vector 1 score, which had a high
loading for leaf:stem ratio and N concentration. Twins
differed from the other varieties in latent vector 2
6–6.5
5.5–6
5–5.5
4.5–5
4–4.5
3.5–4
3–3.5
Strata (cm)
2.5–3
2–2.5
1.5–2
1–1.5
0.5–1
0–0.5
0.00 0.50 1.00 0.00 0.50 1.00 0.00 0.50 1.00 0.00 0.50 1.00 0.00 0.50 1.00
AberDove Belramo Glen AberExcel Twins
No. of leaf contacts per descent in 0.5
cm strata above
g
round level
Figure 1 Number of leaf contacts per descent in 0.5 mm strata above ground level for perennial ryegrass varieties grazed by
sheep.
Intake of perennial ryegrass varieties by sheep
393
2004 Blackwell Publishing Ltd, Grass and Forage Science, 59, 389–398

Citations
More filters

Journal ArticleDOI
Philippe Barre1, Jean Claude Emile1, M. Betin1, Fabien Surault1  +2 moreInstitutions (1)
01 Jul 2006-Agronomy Journal
TL;DR: Differences in short-term intake rate between populations of diploid perennial ryegrass are highlighted, and blade length appears to be an important factor explaining these differences.
Abstract: In sustainable agriculture, adaptation of swards to grazing is a major issue for breeding forage grass cultivars. Understanding the relationships between sward traits and animal production under grazing could help to identify criteria for selection. Intake is the major limiting factor for animal production under grazing. In this paper, short-term intake rate by grazing dairy cows (Bos taurus) is compared between eight diploid perennial ryegrass (Lolium perenne L.) populations. Four replicates per population were measured over four periods (April and May 2001, and April and October 2002) in two experiments per period, that is, intermediate- and late-maturity groups. For each period, sward structure was characterized by tiller density, leaf blade and sheath lengths, and green leaf and total dry matter (DM) yield, while nutritive value was characterized by in vitro dry matter digestibility (IVDMD), percent of DM, N, water-soluble carbohydrate (WSC), and neutral-detergent fiber (NDF) contents. For the late-maturity populations, the population with the shortest leaves had a lower fresh matter intake rate (10.5 kg h -1 ) than the three others (12,12, and 11.6 kg h -1 , respectively). For the intermediate-maturity populations, differences in intake rates among populations were significant (P = 0.06) for all periods and were highly significant (P < 0.0004) in April 2002. In this period, 49% of the variation in fresh matter intake rate could be explained by blade length. In conclusion, differences in short-term intake rate between populations of diploid perennial ryegrass are highlighted. In both maturity groups, blade length appears to be an important factor explaining these differences.

39 citations


Cites background from "Relationships between morphological..."

  • ...For example, it was found that daily intake was positively correlated with N concentration and digestibility of grass ( Orr et al., 2003, 2004 )....

    [...]


Journal ArticleDOI
R. A. Palladino1, Michael O'Donovan2, Emer Kennedy2, John J. Murphy2  +2 moreInstitutions (2)
TL;DR: The study showed that some variation exists between perennial ryegrass cultivars in concentrations of polyunsaturated fatty acids, which may present opportunities to select for this trait, but further research on the developmental stages and degree of leafiness of cultivars is first required.
Abstract: A comparison was made of the fatty acid composition and nutritive value of twelve cultivars of perennial ryegrass (Lolium perenne L) differing in heading date and ploidy level The cultivars were sown in triplicate plots and three sequential cuts of herbage were taken at 20-d intervals during the late spring and early summer to describe the fatty acid composition and other measurements of nutritive value Differences between cultivars were recorded for DM content (P < 0·01) and concentrations of gross energy, neutral-detergent fibre (NDF) and ash (P < 0·05) Diploid cultivars had a higher DM content and concentration of NDF (P < 0·01) than tetraploid cultivars whilst late-heading date cultivars had the lower NDF (P < 0·05), ADF and ash (P < 0·01) concentrations There was variation between cultivars in fatty acid composition Diploid cultivars had a higher concentration of C18:0 (P < 0·01) and C18:1 (P < 0·05) than tetraploid cultivars and late-heading date cultivars had the highest concentrations of total fatty acids, C16:0, C18:2 and C18:3 (P < 0·05) This was predominantly due to the cultivar Tyrella which is a diploid, late-heading cultivar The study showed that some variation exists between perennial ryegrass cultivars in concentrations of polyunsaturated fatty acids, which may present opportunities to select for this trait, but further research on the developmental stages and degree of leafiness of cultivars is first required

39 citations


Journal ArticleDOI
TL;DR: There were significant differences in sheath tube and leaf lengths and in the population density of tillers between and within ploidies, which might have been expected to have influenced intake characteristics, but this was not generally found under rotational grazing with cattle.
Abstract: Four intermediate-heading perennial ryegrass (Lolium perenne L.) varieties, which in previous studies had been associated with high- or low-intake characteristics when swards containing them had been continuously stocked with sheep, were sown as monocultures. They were rotationally grazed, using 1-d paddocks, with core groups of four yearling Simmental x Holstein beef heifers in 2002 and 2003 and ingestive and ruminative behaviour, and sward factors, were measured. There were two diploid (Belramo and Glen) and one tetraploid (Rosalin) perennial ryegrass varieties and one tetraploid hybrid (Lolium x boucheanum Kunth) (AberExcel) variety. Intake rate (IR) was significantly higher in August 2003 for heifers grazing Glen than those grazing Belramo [27.5 vs. 20.6 g dry matter (DM) min(-1); P = 0.019], but there were no significant differences between varieties in two other measurement periods. This is in contrast to previous results with sheep when IR were significantly higher for Glen than Belramo and for AberExcel than Rosalin. Total jaw movement rates during grazing were significantly higher for heifers on the tetraploid swards than those on the diploid swards (87.7 vs. 83.6 jaw movements min(-1); P = 0.023) in September 2002. Ruminating time was significantly lower for heifers on the tetraploid swards than those on the diploid swards (453 vs. 519 min 24 h(-1); P = 0.012) in July 2002. Digestibility of grass snips was significantly higher on the tetraploid than the diploid swards [697 vs. 680 g digestible organic matter (DOM) kg(-1) DM; P = 0.042] in September 2003 and, within diploids, was significantly higher for Glen than Belramo (696 vs. 663 g DOM kg(-1) DM; P = 0.014). There were significant differences in sheath tube and leaf lengths and in the population density of tillers between and within ploidies, which might have been expected to have influenced intake characteristics, but this was not generally found under rotational grazing with cattle. In order to separate the effects of defoliation interval from those of grazing style of the different ruminant species, it is suggested that grass variety evaluations using continuously stocked cattle swards are required.

22 citations


Cites background or result from "Relationships between morphological..."

  • ...…fifteen intermediate-heading perennial ryegrass (Lolium perenne L.) varieties when they were continuously stocked with sheep and subsequently explored the extent to which, for five of these varieties, these differences could be explained by chemical and morphological traits (Orr et al., 2004a)....

    [...]

  • ...Yearling dairy heifers rotationally stocked on perennial ryegrass swards (Orr et al., 2004b) had generally similar total jaw movement rates during the first hour on a new paddock to those in the present experiment....

    [...]

  • ...The biting and total jaw movement rates measured by Orr et al. (2004b), when the dairy heifers entered the new paddock, may have been marginally higher because the grazing periods in that experiment were of 2–3 weeks duration, so the heifers may have been hungrier (Greenwood and Demment, 1988)…...

    [...]

  • ...Effects of sward chemical and morphological factors on IR Differences between grass varieties in IR by sheep have been related in part to sward factors in previous studies (Orr et al., 2003, 2004a)....

    [...]

  • ...While grazing, cattle have a lower total jaw movement rate (e.g. Orr et al., 2004b) than sheep (e.g. Penning et al., 1991), and sheep also have higher proportions of the grazing jaw movements (between one-half and two-thirds) as chews depending on sward height (Penning et al., 1994)....

    [...]


Journal ArticleDOI
01 Jan 2005-Euphytica
TL;DR: The micro-sward methodology provides a rapid, low-cost assessment method with a low seed requirement to screen for intake traits during breeding programmes and during variety evaluation and there is a need to develop further this methodology in order to allow small-scale simulation of other defoliation regimes, for example continuous stocking.
Abstract: Two diploid (Belramo and Glen), one tetraploid (Rosalin) and one tetraploid hybrid (Lolium× boucheanum Kunth) (AberExcel) intermediate-heading perennial ryegrass (Lolium perenne L.) varieties were sown in boxes (85×44×14 cm) to create micro-swards. Once established, these were defoliated at approximately 21-day intervals before being offered to individual yearling Simmental × Holstein beef heifers in short-term tests. Bite mass measured in these tests was compared with bite mass for groups of similar heifers which were rotationally stocked on the same four varieties. The boxes were weighed (± 0.1 g) before and after a period during which the heifers were allowed to take approximately 50 bites. The micro-sward methodology was developed in, 2002 and bite masses for Belramo, Glen, Rosalin and AberExcel, respectively, were 0.44, 0.46, 0.49 and 0.50 g DM bite−1 compared with 0.48, 0.49, 0.50 and 0.50 g DM bite−1 measured for rotationally stocked cattle. In 2003, the values for bite mass were 0.40, 0.41, 0.41 and 0.43 g DM bite−1 measured using sward boxes and 0.31, 0.41, 0.34 and 0.37 g DM bite−1 for rotationally stocked cattle. Whilst the rankings were similar within ploidy for the two assessment methods, there were no significant differences between the varieties. The micro-sward methodology provides a rapid, low-cost assessment method with a low seed requirement to screen for intake traits during breeding programmes and during variety evaluation. Now there is a need to develop further this methodology in order to allow small-scale simulation of other defoliation regimes, for example continuous stocking.

17 citations


Cites background or methods from "Relationships between morphological..."

  • ...However, Orr et al. (2003, 2004b) did not find significant correlations between intake of perennial ryegrass varieties for continuously-stocked sheep and green leaf mass or water soluble carbohydrate concentration and suggested that other traits should be examined which affect bite mass and intake....

    [...]

  • ...Bite mass for rotationally stocked heifers grazing in groups in 1-day paddocks (each 0.02 ha) was measured using a weighing technique, described in detail by Orr et al. (2004a)....

    [...]

  • ...Now there is a need to develop further this methodology in order to allow small-scale simulation of continuous stocking conditions, where intake differences have been shown with sheep (Orr et al., 2003, 2004b)....

    [...]

  • ...…50 and then successively reweigh the box, so that the bite mass response curves could be established for a large number of contrasting varieties as sward height/mass is reduced (Barrett et al., 2001; McGilloway et al., 1999; Orr et al., 2004a) as would be the case in rotationally-stocked swards....

    [...]


Journal ArticleDOI
TL;DR: The lower level found here is likely to impact on potential volatilization, denitrification and leaching losses, and these aspects should be examined further to see the extent to which semi-improved grasslands containing increased plant diversity compared with improved grasslands can deliver higher resource protection, as well as enhanced grassland faunal diversity and abundance.
Abstract: There is increased global interest in the environmental impacts of farming, including the need to prevent the contamination of soil, water and air with excessive amounts of nitrogen (N) and phosphorus (P) in grazed systems. Reduction in grazing intensity has frequently been recommended to meet biodiversity and production goals in sustainable grazing systems. The objective of this experiment was to measure N and P ingestion and excretion by beef cattle grazing semi-natural pastures at two grazing intensities (Moderate or Lenient). The cattle grazing at Moderate grazing intensity had significantly more defaecations each day than those grazing at Lenient intensity (9.5 vs. 7.5) and tended to have more urinations (7.0 vs. 5.8). For the Moderate and Lenient treatments, respectively, 113 vs. 76 g N d(-1) was excreted compared with 136 vs. 94 g N d(-1) ingested; 12 vs. 8 g P d(-1) was excreted compared with 13 vs. 10 g P d(-1) ingested and urine N comprised 0.51 and 0.52 of the total N excreted each day. In improved, intensively managed grassland systems, urine N comprises a much higher proportion (approximately 0.700.85) of the daily total N excreted. The lower level found here is likely to impact on potential volatilization, denitrification and leaching losses, and these aspects should be examined further to see the extent to which semi-improved grasslands containing increased plant diversity compared with improved grasslands can deliver higher resource protection, as well as enhanced grassland faunal diversity and abundance.

17 citations


References
More filters

Journal ArticleDOI
TL;DR: This review discusses the potential use of plant wax components, especially n-alkanes, as markers for estimating herbage intake, estimating the botanical composition of consumed herbage and studying digesta kinetics, and suggests that natural alkanes could prove excellent markers for studies of particle breakdown and digesta flow.
Abstract: This review discusses the potential use of plant wax components, especially n-alkanes, as markers for estimating herbage intake, estimating the botanical composition of consumed herbage and studying digesta kinetics. Previous approaches to making these measurements are discussed briefly. Attention is drawn to the fact that current methods for estimating intake do not adequately allow for differences between individual animals. It is also suggested that the markers currently used to estimate botanical composition or study digesta kinetics are inadequate. The nature of the chemical constituents of plant waxes is briefly discussed and the concept of using alkanes to estimate intake is introduced. Particular emphasis is given to the fact that although the recovery of alkanes in faeces is not complete, intake can still be estimated using a pair of alkanes (one natural, one dosed) provided these have similar faecal recoveries. The accuracy of estimation of intake is discussed in terms of: obtaining a representative sample of herbage; alkane dosing and faecal sampling procedures; validity of the assumption of similar recoveries for the natural and dosed alkanes; sample preparation and analysis. Published comparisons of estimated and actual intakes are presented, with the conclusion that satisfactory results are obtained if intake is estimated using natural C33 alkane and dosed C32 alkane. The use of the different patterns of alkanes in herbage species, as a means of estimating botanical composition, is then discussed. Results are presented showing this can be done successfully with herbage mixtures or oesophageal extrusa. Procedures are then described for making the corrections for incomplete faecal alkane recovery, necessary to estimate the botanical composition of the herbage consumed by the free-grazing animal. This allows the quantification of the intake of individual plant species by individual animals, and it is suggested that this can be achieved without the need for oesophageally-fistulated (OF) animals. Differences in alkane levels between plant parts within a species are then discussed. It is suggested that these can lead to error in the estimation of intake, if OF animals should consume plant parts different from those consumed by the test animals. However, it is also suggested that differences in alkane levels between plant parts can be used to quantify the intake of these parts, in a manner analogous to the estimation of the intake of individual plant species. The usefulness of alkanes in studies of digesta kinetics is then discussed, principally in relation to the natural alkanes, which remain intimately associated with plant particles in the gut. It is suggested that natural alkanes could prove excellent markers for studies of particle breakdown and digesta flow. The preparation of natural 14C-labelled alkane, for use as a pulse dose in mean retention time studies, is also discussed.

466 citations


"Relationships between morphological..." refers methods in this paper

  • ...Daily intake, eating time, intake rate and ruminating time Grass intake was measured using a modification of the n-alkane method of Dove and Mayes (1991)....

    [...]

  • ...Mean daily DM intake by the group was calculated from the assayed release rate of C32alkane (44Æ9 mg d) and the concentrations of C32and C33-alkane (tritriacontane) in herbage and faeces (Dove and Mayes, 1991)....

    [...]

  • ...Mean daily DM intake by the group was calculated from the assayed release rate of C32alkane (44Æ9 mg d)1) and the concentrations of C32and C33-alkane (tritriacontane) in herbage and faeces (Dove and Mayes, 1991)....

    [...]


Journal ArticleDOI
TL;DR: The results of this exploratory study suggest that prediction of grazing responses on the basis of easily measured plant traits is feasible and consistent between similar grazing systems in different regions, challenging the precept that intense cattle grazing necessarily favours species with tough, unpalatable, leaves.
Abstract: Summary 1 Range management is based on the response of plant species and communities to grazing intensity. The identification of easily measured plant functional traits that consistently predict grazing response in a wide spectrum of rangelands would be a major advance. 2 Sets of species from temperate subhumid upland grasslands of Argentina and Israel, grazed by cattle, were analysed to find out whether: (i) plants with contrasting grazing responses differed in terms of easily measured vegetative and life-history traits; (ii) their grazing response could be predicted from those traits; (iii) these patterns differed between the two countries. Leaf mass, area, specific area (SLA) and toughness were measured on 83 Argentine and 19 Israeli species. Species were classified by grazing response (grazing-susceptible or grazing-resistant) and plant height ( 40 cm) as well as by life history (annual or perennial) and taxonomy (monocotyledon or dicotyledon). 3 Similar plant traits were associated with a specific response to grazing in both Argentina and Israel. Grazing-resistant species were shorter in height, and had smaller, more tender, leaves, with higher SLA than grazing-susceptible species. Grazing resistance was associated with both avoidance traits (small height and leaf size) and tolerance traits (high SLA). Leaf toughness did not contribute to grazing resistance and may be related to selection for canopy dominance. 4 Plant height was the best single predictor of grazing response, followed by leaf mass. The best prediction of species grazing response was achieved by combining plant height, life history and leaf mass. SLA was a comparatively poor predictor of grazing response. 5 The ranges of plant traits, and some correlation patterns between them, differed markedly between species sets from Argentina and Israel. However, the significant relationships between plant traits and grazing response were maintained. 6 The results of this exploratory study suggest that prediction of grazing responses on the basis of easily measured plant traits is feasible and consistent between similar grazing systems in different regions. The results challenge the precept that intense cattle grazing necessarily favours species with tough, unpalatable, leaves.

434 citations


"Relationships between morphological..." refers background in this paper

  • ...related to morphological and chemical characteristics (Diaz et al., 2001; Liu et al., 2002) that could be targeted for those varieties destined for use under grazing...

    [...]

  • ...Here it is explored whether the differences in grass intake measured by Orr et al. (2003) were related to morphological and chemical characteristics (Diaz et al., 2001; Liu et al., 2002) that could be targeted for those varieties destined for use under grazing management (Stone, 1994)....

    [...]


Journal ArticleDOI
T. Arthur Thomas1Institutions (1)
Abstract: An automated procedure for the estimation of total soluble carbohydrate in water extracts of herbage is described. Addition of different sugars to grass extracts showed good recoveries (96.5–104.5%) for glucose, fructose, sucrose and fructosan. Analysis of sugar mixtures similar in composition to grass extracts also gave good recoveries (98.7–100%). The automated technique enabled 20 samples per hour to be analysed with a lower coefficient of variation (1.96%) than for a manual anthrone method (3.85%).

414 citations


"Relationships between morphological..." refers methods in this paper

  • ...The snipped grass samples were analysed for digestibility of organic matter in the DM (DOMD in vitro; Jones and Haywood, 1975), for nitrogen (N) concentration by the Kjeldahl method, with copper sulphate as a catalyst, using a Tecator 1030 auto analyser (Tecator, 1987) and for water-soluble carbohydrate (WSC) concentration (Thomas, 1977)....

    [...]

  • ...…digestibility of organic matter in the DM (DOMD in vitro; Jones and Haywood, 1975), for nitrogen (N) concentration by the Kjeldahl method, with copper sulphate as a catalyst, using a Tecator 1030 auto analyser (Tecator, 1987) and for water-soluble carbohydrate (WSC) concentration (Thomas, 1977)....

    [...]


Journal ArticleDOI
D. Iowerth1, H. Jones1, Margaret V. Hayward1Institutions (1)
TL;DR: Using the two stage technique, closely similar regression lines were obtained for predicting the in vitro digestibility of both grasses and legumes and the technique is proposed as a more rapid, convenient and precise method of predicting digestibility than the usual in vitro procedure.
Abstract: Cellulase preparations from different fungi differed markedly in their ability to solubilise herbage and cellulose; T. viride cellulase was the most active, solubilising 70% of cellulose paper in 24 h. The correlation of cellulase solubility with the in vivo and in vitro dry matter digestibility of grasses, and with the in vitro digestibility of legumes was markedly improved by pretreatment of the herbage with acid pepsin. Using the two stage technique, closely similar regression lines were obtained for predicting the in vitro digestibility of both grasses and legumes. Use of the pepsin treatment also enabled a less active Basidiomycete cellulase to be used with results very similar to those obtained with the T. viride enzyme. The technique is proposed as a more rapid, convenient and precise method of predicting digestibility than the usual in vitro procedure.

283 citations


"Relationships between morphological..." refers methods in this paper

  • ...The snipped grass samples were analysed for digestibility of organic matter in the DM (DOMD in vitro; Jones and Haywood, 1975), for nitrogen (N) concentration by the Kjeldahl method, with copper sulphate as a catalyst, using a Tecator 1030 auto analyser (Tecator, 1987) and for water-soluble carbohydrate (WSC) concentration (Thomas, 1977)....

    [...]

  • ...The snipped grass samples were analysed for digestibility of organic matter in the DM (DOMD in vitro; Jones and Haywood, 1975), for nitrogen (N) concentration by the Kjeldahl method, with copper sulphate as a catalyst, using a Tecator 1030 auto analyser (Tecator, 1987) and for water-soluble…...

    [...]


Journal ArticleDOI
TL;DR: The total area of foliage per unit area of land can be estimated from the number of contacts with foliage made by point quadrats inclined at appropriate angles, and the distribution of this foiiage area with height above ground be estimated by recording the heights at which the contacts occur.
Abstract: The total area of foliage per unit area of land can be estimated from the number of contacts with foliage made by point quadrats inclined at appropriate angles, and the distribution of this foiiage area with height above ground be estimated by recording the heights at which the contacts occur. These estimates, unlike those based on vertical and horizontal quadrats, are not depressed by variability in foliage angle (inclination of foliage to the horizontal). The foliage angle can be estimated by comparing the numbers of contacts made by quadrats inclined at two different angles, but this estimate is less satisfactory than one based on vertical and horizontal quadrats. Accurate estimates of both foliage area and foliage angle can be obtained by using a combination of vertical, inclined, and horizontal quadrats. This paper also discusses the application of point quadrat methods to stems as well as leaves, and considers certain practical aspects of point quadrat use.

268 citations


"Relationships between morphological..." refers methods in this paper

  • ...This angle was determined (Warren Wilson, 1963) from consideration of the grass foliage angle (inclination of foliage to the horizontal)....

    [...]