Spray-topping annual grass pasture with glyphosate to delay loss of feeding value during summer. IV. Diet composition, herbage intake, and performance in grazing sheep

1999 ◽  
Vol 50 (4) ◽  
pp. 487 ◽  
Author(s):  
B. J. Leury ◽  
C. Siever-Kelly ◽  
R. J. Simpson ◽  
K. L. Gatford ◽  
H. Dove
Keyword(s):  
Diet Composition ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Sheep Grazing ◽  
Annual Grass ◽  
Plant Parts ◽  
Seed Head ◽  
Herbage Intake ◽  
Grazing Sheep ◽  
Days After Anthesis

We report the effects of spray-topping annual grass pasture with glyphosate (180 g a.i./ha as Roundup CT, at the seed head emergence stage) on the nutritive value of herbage and on subsequent performance of grazing sheep. Eight 1-ha plots, consisting of 4 sprayed and 4 unsprayed (control) plots, were set-stocked with Merino wethers (18 months old, 12 sheep/ha) from 8 days after anthesis in the control plots (late spring) until 165 days after anthesis (mid-autumn). In 4 periods (15–20, 36–41, 71–76, and 99–104 days after anthesis; Periods 1–4, respectively) sheep were dosed with synthetic alkanes and herbage and faecal samples were taken, in order to estimate diet composition (in terms of plant parts), faecal output, herbage intake, and the digestibility of the whole diet. As described in our earlier papers, spray-topping reduced the yield of pasture dry matter, but also slowed the loss of water-soluble carbohydrate (WSC) and digestibility during pasture senescence. The present paper shows that as a result, sheep grazing sprayed herbage in Periods 1 and 2 consumed significantly more organic matter (OM) and digestible OM (DOM) than sheep grazing the control pasture. Their diet contained a higher proportion of stem with a higher WSC concentration than that of the sheep grazing the control plots. The proportions of different plant parts (leaf blade+sheath, stem, seed head) in the diet of both the plot sheep and oesophageally fistulated (OF) sheep, which grazed treatments for short periods, differed significantly between treatments in all periods. However, the compositions of the diets selected by plot and OF sheep were similar. These results confirmed diet preferences measured using housed sheep and demonstrate the usefulness of alkane-based procedures for quantifying diet composition and intake in grazing animals. As a result of their higher intake of DOM, sheep grazing sprayed herbage had a significantly higher liveweight gain over the first 2 periods (40 g/day). In Period 3, sheep grazing sprayed herbage consumed more OM than sheep grazing control herbage. However, DOM intakes from sprayed or control plots were not significantly different in either Period 3 or Period 4, and were lower than in Periods 1 and 2. Sheep grazing both treatments lost liveweight at a similar rate over this time. Wool growth in sheep grazing sprayed herbage was improved by 10% during the experimental period; wool strength was also improved significantly. The implications for the management of sheep grazing spray-topped pastures over summer are discussed.

Spray-topping annual grass pasture with glyphosate to delay loss of feeding value during summer. I. Effects on pasture yield and nutritive value

1999 ◽  
Vol 50 (4) ◽  
pp. 453 ◽  
Author(s):  
B. J. Leury ◽  
C. Siever-Kelly ◽  
R. J. Simpson ◽  
K. L. Gatford ◽  
T. A. Ciavarella ◽  
...  
Keyword(s):  
Nutritive Value ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Annual Grass ◽  
Plant Parts ◽  
Seed Head ◽  
Grass Sward ◽  
Pasture Yield ◽  
Days After Anthesis

Annual grass pasture (mainly annual ryegrass) was treated at seed head emergence (12 October 1990) with the herbicide glyphosate to delay loss of digestibility during late spring and summer. The lowest rate of glyphosate application needed to retain a high digestibility in the dry matter (DM) of the senescent grass sward was 180 g a.i./ha. The in vitro DM digestibility of control (unsprayed) pasture declined rapidly from relatively high levels near anthesis (28 October) (77–86%, leaves and seed head; 66%, stems) until about 38 days after anthesis (51–71%, leaves and seed head; 24%, stem). Thereafter, the digestibility of the plant parts did not change appreciably over at least 4 months. Treatment with glyphosate significantly slowed the loss in digestibility of stem, leaf sheaths, and seed head but did not affect the decline in digestibility of leaf blades. For example, the digestibility of stem in the sprayed pasture was 26 percentage units higher than that in the control pasture 38 days after anthesis. If the time at which digestibility of stems reached 50% is taken as an indication, the effective delay in loss of digestibility was of the order of 5 weeks. However, improved digestibility in the treated pasture was achieved at the expense of pasture yield, with the peak yield of control pasture being 4 t DM/ha (45%) higher than that of the treated pasture. Improved digestibility in treated grass pasture was mainly associated with delayed loss of water-soluble carbohydrates (WSC), except in the seed head. Improved cell wall (neutral detergent fibre) digestibility also contributed to varying degrees and was the main factor contributing to improved digestibility in the seed head. The major WSC present in the treated pasture was fructan. The crude protein concentrations of all plant parts of the senescent pasture, except the leaf blades, were also increased by treatment with glyphosate.

Spray-topping annual grass pasture with glyphosate to delay loss of feeding value during summer. III. Quantitative basis of the alkane- based procedures for estimating diet selection and herbage intake by grazing sheep

1999 ◽  
Vol 50 (4) ◽  
pp. 475 ◽  
Author(s):  
H. Dove ◽  
J. T. Wood ◽  
R. J. Simpson ◽  
B. J. Leury ◽  
T. A. Ciavarella ◽  
...  
Keyword(s):  
Diet Composition ◽  
Nutritive Value ◽  
Diet Selection ◽  
Leaf Sheath ◽  
Multivariate Statistical ◽  
Plant Parts ◽  
Seed Head ◽  
Herbage Intake ◽  
Quantitative Basis ◽  
Objective Basis

Previous papers in this series have demonstrated that, when annual pastures were sprayed at seed head emergence with low rates of the herbicide glyphosate, the nutritive value of the sprayed herbage was improved. Housed sheep preferred sprayed herbage to unsprayed herbage and, within sprayed herbage, appeared to have a preference for stem material. The housed sheep ate more of the sprayed material and their weight gains were improved. If such responses occurred in grazing animals, they could result in substantial improvements in animal liveweights or wool production. The present paper describes the alkane-based procedures used to investigate diet selection and herbage intake in grazing animals, with the emphasis placed on methodological and statistical issues. The alkane concentrations in the plant fractions (leaf, leaf sheath, stem, seed head) of sprayed and unsprayed herbage are reported. Similarly, the alkane concentrations in extrusa samples collected by oesophageally fistulated sheep given access to the grazed areas, and in the faeces of sheep grazing the areas, are reported. Patterns of alkane concentrations in extrusa and faeces were similar and indicated that, in the short term, oesophageally fistulated animals consumed a diet of similar composition to that selected by the animals resident on the plots. Using these data for alkane concentrations, multivariate statistical analyses are presented which provide an objective basis for selecting the alkanes to be used in the estimation of diet selection. The results of the first of 4 grazing periods are presented, as an example of the application of the alkane-based procedures for estimating herbage intake and, in particular, diet composition. Use of these techniques indicated that, when given access to sprayed senescent pasture, sheep consumed more digestible dry matter and selected more of it from the stem fraction than was the case with unsprayed herbage. These results are similar to those found with housed animals and demonstrate that patterns of herbage and faecal alkane concentrations can be used to estimate diet composition of grazing animals in terms of the plant parts on offer

Spray-topping annual grass pasture with glyphosate to delay loss of feeding value during summer. II . Herbage intake, digestibility, and diet selection in penned sheep

1999 ◽  
Vol 50 (4) ◽  
pp. 465 ◽  
Author(s):  
B. J. Leury ◽  
C. Siever-Kelly ◽  
R. J. Simpson ◽  
K. L. Gatford ◽  
H. Dove
Keyword(s):  
Volatile Fatty Acids ◽  
Nutritive Value ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Individual Plant ◽  
Plasma Urea ◽  
Preference Testing ◽  
Plant Parts ◽  
Seed Head ◽  
Herbage Intake

The treatment of annual ryegrass–silver grass pasture with the herbicide glyphosate at seed head emergence delayed the loss of soluble carbohydrates and improved herbage digestibility. The present study investigated whether this improvement in nutritive value had any influence on the diet preference, intake, and performance of housed sheep. Since the effects of glyphosate on digestibility were most marked in stem tissue, preference was examined not only in relation to sprayed v. unsprayed herbage, but also in terms of preference for individual plant parts. In the preference testing, sheep showed a marked preference for sprayed rather than unsprayed herbage. They also consumed more of it, such that their digestible dry matter intake from sprayed herbage was nearly twice that from unsprayed herbage. When sheep were offered different plant fractions from the control herbage, they selected against stem material and preferred leaf or seed head. By contrast, when offered fractions from the sprayed material, they preferred stem to leaf, but showed no strong preference for stem over seed head. Preference was related more to the soluble carbohydrate content of a plant part than its digestibility, and only when soluble carbohydrate contents were similar was there preference for the more digestible material. The consumption of sprayed herbage, compared with control herbage, led to higher concentrations of rumen volatile fatty acids in the period 4 h after feeding. Moreover, the feeding of these herbages over a 6-week period resulted in significant reductions in pre-feeding plasma urea and β-hydroxybutyrate concentrations. When control herbage was fed with supplements of fructose, urea, or fructose+urea, in an attempt to mimic the possible differences in nutritive value between control and sprayed herbage, the responses in rumen and blood metabolites were less marked than when sprayed herbage was fed. As a consequence of the higher nutritive value of the sprayed herbage and the higher intakes by the animals fed this material, sheep fed sprayed herbage were able to maintain weight over the feeding period, whereas those offered the control herbage lost weight at 130–150 g/day

Comparison of the alkane-based herbage intakes and the liveweight gains of young sheep grazing forage oats, dual-purpose wheat or phalaris-based pasture

2015 ◽  
Vol 55 (10) ◽  
pp. 1230 ◽  
Author(s):  
H. Dove ◽  
W. M. Kelman
Keyword(s):  
Diet Composition ◽  
Sheep Grazing ◽  
Feeding Trial ◽  
Dual Purpose ◽  
Herbage Intake ◽  
Grazing Systems ◽  
Metabolisable Energy ◽  
Long Chain Alcohol ◽  
Long Chain

Two experiments were conducted between 2004 and 2006 near Canberra, Australia, to provide information about herbage intake and liveweight gains of young sheep grazing dual-purpose crop cf. pasture. In an indoor feeding trial (2004–2005), dual-purpose wheat (cv. Mackellar) and oats (cv. Blackbutt) had estimated organic matter (OM) digestibilities of 0.849 ± 0.0070 and 0.847 ± 0.0001, respectively. The indoor trial also provided data for the concentrations and faecal recoveries of the cuticular wax alkane and long-chain alcohol (LCOH) markers used to estimate diet composition and intake in the grazing trial. The faecal recoveries of both alkanes and LCOH were well described by asymptotic regressions. Alkane recovery differed between crops, though not between years. Faecal LCOH recovery did not differ between crops or years. Under grazing conditions in 2004–2005, the OM digestibility (OMD) of crop herbage was 0.825–0.871, significantly higher than the OMD of phalaris-based pasture (0.752–0.758). The estimated OMD of wheat in 2006 (0.792) was lower than in the earlier years. Sheep consumed ~1 kg/day digestible OM intake (DOMI) from crop in 2004–2005. In 2004 this was significantly higher than the DOMI of sheep grazing pasture (0.75 kg/day) whereas in 2005 the DOMI from pasture was slightly (1.15 kg/day) but significantly higher than that from crop (mean 0.97 kg/day). Regardless of the source of herbage consumed, sheep daily liveweight gains were in the range 200–250 g/kg DOMI. Liveweight gains of sheep grazing crop were also predicted from their calculated metabolisable energy intakes and requirements for maintenance and were within 1% of the observed liveweight gains. Our results demonstrate that in high-rainfall areas, the quantity and quality of the herbage provided by sowing dual-purpose crops, and the resultant increased animal liveweight gains, justify the inclusion of dual-purpose crops in grazing systems.

Uniculm and conventional tillering barley accessions under northern growing conditions

2011 ◽  
Vol 150 (3) ◽  
pp. 335-344 ◽  
Author(s):  
P. MÄKELÄ ◽  
S. MUURINEN
Keyword(s):  
Grain Yield ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Plant Parts ◽  
Barley Cultivars ◽  
Growing Seasons ◽  
Northern Latitudes ◽  
Growing Conditions ◽  
Yield Formation ◽  
Water Soluble Carbohydrate

SUMMARYAt high northern latitudes, growing seasons are short with long days. In these conditions, tillering is an unwanted trait in barley (Hordeum vulgare L.), because the grains on tillers develop later than those on the main stem and are often harvested before they are fully mature, leading to reductions in overall quality. Hence, the uniculm growth habit has been considered an interesting option for boreal barley production. The aim of the present study was to determine the differences in the yield formation of conventional tillering and uniculm barley, using two pairs of near-isogenic lines and two controls. Uniculm and conventional tillering barley were grown in three experiments conducted at Suitia Experimental Farm, University Helsinki, Finland during 1999–2001. Samples were collected frequently to monitor the biomass and leaf area accumulation. Water-soluble carbohydrate content was analysed at anthesis and at maturity in different plant parts. At maturity, the numbers of spikes/plant and grains/spike were calculated and grain yield weighed. The grain yield of the uniculm barleys was stable over these growing seasons, but it was only half that of the conventional barley cultivars due to the absence of spike-bearing tillers, lower spike grain number and spike weight. In addition, the ability to transport photosynthesized carbohydrates to grains may have been reduced. Thus, it seems that uniculm barleys do not provide further improvement in barley yield.

Differences between related grasses, times of year and plant parts in digestibility and chemical composition

1996 ◽  
Vol 127 (3) ◽  
pp. 311-318 ◽  
Author(s):  
D. Wilman ◽  
Y. Gao ◽  
M. A. K. Altimimi
Keyword(s):  
Cell Wall ◽  
Lolium Multiflorum ◽  
Water Soluble ◽  
Italian Ryegrass ◽  
Soluble Carbohydrate ◽  
Meadow Fescue ◽  
Cell Content ◽  
Plant Parts ◽  
Dry Matter Digestibility ◽  
Water Soluble Carbohydrate

SUMMARYTrue dry matter digestibility, proportion of cell content, digestibility of cell wall, N and water-soluble carbohydrate were determined in eight related grasses in February, June and September in each of three years. In a separate experiment, true dry matter digestibility, proportion of cell content and digestibility of cell wall were determined in five plant parts of vegetative tillers of two grasses in February, April, June, August, October and December in each of two years.Perennial ryegrass (Lolium perenne) was the most digestible grass and tall fescue (Festuca arundinacea) and Westerwolds ryegrass (Lolium multiflorum var. Westerwoldicum) were the least digestible. Italian ryegrass (Lolium multiflorum) was high in proportion of cell content, but not in digestibility of cell wall. Meadow fescue (Festuca pratensis) was high in digestibility of cell wall, but low in proportion of cell content. Perennial ryegrass and hybrid ryegrass were high, and tall fescue low, in both proportion of cell content and digestibility of cell wall. Ryegrasses were lower than fescues in concentration of N and higher than the fescues in water-soluble carbohydrate; ryegrass × meadow fescue hybrids were intermediate between the parent species in N and watersoluble carbohydrate.Grass sampled in June and August was lower in both proportion of cell content and digestibility of cell wall than grass sampled at cooler times of year. Grass sampled in February was high in proportion of cell content and N, intermediate to high in digestibility of cell wall and intermediate in water-soluble carbohydrate.Expanding leaf blades of perennial and Italian ryegrass were higher than expanded blades and sheaths in digestibility of cell wall and similar to expanded blades and higher than sheaths in proportion of cell content. Cell wall was less digestible in the tip than in the middle and basal portions of expanded leaf blades.

Effect of pasture availability and shearing stress on herbage intake of grazing sheep

1963 ◽  
Vol 14 (3) ◽  
pp. 364 ◽  
Author(s):  
JL Wheeler ◽  
TF Reardon ◽  
LJ Lambourne
Keyword(s):  
Organic Matter ◽  
Cold Stress ◽  
Dry Weight ◽  
Shearing Stress ◽  
Sheep Grazing ◽  
Herbage Intake ◽  
Digestible Organic Matter ◽  
Grazing Sheep ◽  
Index Methods

Digestible organic matter (D.O.M.) intakes of sheep grazing various pastures were measured by faecal index methods in three 4- to 6-week experiments. No correlation could be found between the weight of pasture available (over the range 150–2900 Ib dry weight per acre of green herbage) and the D.O.M. intake of sheep. During two experiments the sheep were shorn. Shortly after, voluntary D.O.M. intakes rose significantly by 42–62%. Concurrently the hay intake of other sheep yarded nearby rose by 20–51% following shearing. Cold stress is probably responsible for these increases.

The summer nutrition of immature sheep: The nitrogen excretion of grazing sheep in relation to supplements of available energy and protein in a Mediterranean environment.

1969 ◽  
Vol 20 (1) ◽  
pp. 125 ◽  
Author(s):  
WG Allden ◽  
CC Jennings
Keyword(s):  
Balance Sheet ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Nitrogen Excretion ◽  
Control Treatment ◽  
Sheep Grazing ◽  
Available Energy ◽  
Herbage Intake ◽  
Grazing Sheep ◽  
Sparing Effect

The nitrogen excretion of 24 yearling Merino sheep grazing the summer herbage of annual grass-subterranean clover (Trifolium subterraneum L.) sown pastures was measured over four consecutive periods of 28 days in relation to supplementation with available energy (E) and nitrogen (N). The experiment was of change-over design and included nine combinations of supplement E1, E2, E3 x N1, N2, N3 and an unsupplemented (control) treatment; the respective daily allowance of E was 11 3, 227, and 340 g total digestible nutrients daily, and of N supplied as protein 4,8, and 12 g/day. Unsupplemented sheep grazing mature pasture herbage excreted 23.4 g N/day in urine and faeces. Supplementary energy produced an N-sparing effect whereas added protein was associated with an increased excretion of N. Urinary N accounted for all the changes in N excretion, the faecal N component remaining constant throughout the four periods. Relative changes in herbage intake were estimated: as the level of E (dry matter) increased the estimated herbage intake of sheep was observed to fall linearly, but no significant change in estimated herbage intake was associated with changing N. Significant increases in wool production (P<0.05) were associated with supplementary N. Direct and indirect estimates of the N turnover of the grazing sheep are compared, and a crude N balance sheet is presented. Supporting data are presented which suggest that the N intakes of sheep grazing the mature herbage of sown clover-grass pastures in southern Australia are commonly of the order of 12-18 g N/day.

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