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. 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. 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

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.

scholarly journals 111 Metsulfuron and variable nitrogen application rates on infected tall fescue: effects on stocker performance, forage yield, nutritive value, ergovaline concentration and botanical composition

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 31-31
Author(s):  
Kevin R Meng ◽  
Eric Bailey ◽  
Josh Zeltwanger ◽  
Hannah Allen ◽  
Mikaela Adams ◽  
...  
Keyword(s):  
Species Composition ◽  
Tall Fescue ◽  
Nutritive Value ◽  
Ergot Alkaloids ◽  
Fertilization Rate ◽  
Forage Yield ◽  
Nitrogen Application ◽  
Forage Production ◽  
Seed Head ◽  
Application Rates

Abstract Chemical seed-head suppression of endophyte infected tall fescue (Lolium arundinaceum) improves stocker cattle performance but may decrease forage yield. Spring nitrogen application increases tall fescue growth with a concomitant increase in ergot alkaloids, produced by the symbiotic endophyte Epichloë coenophiala. We hypothesized that greater amounts of nitrogen applied to tall fescue would increase forage yield and offset losses in forage production from chemical suppression of seed-heads with metsulfuron without effect on alkaloid concentration. Ninety-six steers (270 ± 20 kg) were randomly assigned to one of sixteen paddocks (1.8 ha) on April 18 and continuously grazed for 57 d. Paddocks were blocked by previous use (n = 4) and randomly assigned to one of four treatments; no metsulfuron, no nitrogen (NEGCON), metsulfuron with 0 (MET0), 67 (MET67), or 134 (MET134) kg/ha of ammonium nitrate, applied March 11. Steers grazing MET0 paddocks were removed 17 d early due to insufficient forage availability. Steer weight, forage yield, forage nutritive value and ergot alkaloids in forage samples were measured monthly. Seed-head frequency and species composition were determined in June. Metsulfuron application reduced (P < 0.01) tall fescue seed-heads by 80%. Metsulfuron decreased (P = 0.03) ergovaline but ergovaline increased (P < 0.01) at each monthly sampling across treatments. Nitrogen had no impact on ergovaline concentration (P = 0.50). Forage yield tended to be least (P = 0.07) for MET0, intermediate for NEGCON and MET67, and tended to be greatest for MET134 (P = 0.08). Steer ADG was not affected by treatment (P < 0.80). Metsulfuron decreased NDF (P=0.02) regardless of fertilization rate. Forage CP increased with fertilization (P < 0.01) and no differences were detected between NEGCON and MET0 (P = 0.45). Species composition was not impacted (P >0.07) by treatment. Metsulfuron decreased seed-head growth and ergovaline concentration in tall fescue. Additional nitrogen fertilizer ameliorated forage yield lost to metsulfuron application but did not impact steer gain.

Diet composition, herbage intake and digestibility in Inner Mongolian Cashmere goats grazing on native Leymus chinensis plant communities

2008 ◽  
Vol 116 (1-3) ◽  
pp. 146-155 ◽  
Author(s):  
Zewei Sun ◽  
Daowei Zhou ◽  
Luis M.M. Ferreira ◽  
Qingzhen Zhong ◽  
Yujie Lou
Keyword(s):  
Plant Communities ◽  
Diet Composition ◽  
Leymus Chinensis ◽  
Herbage Intake ◽  
Cashmere Goats

scholarly journals Estimation of pasture herbage intake by beef cattle based on n-alkanes as markers

2017 ◽  
Vol 70 (1) ◽  
Author(s):  
Piotr Nowakowski ◽  
Katarzyna Czyz ◽  
Marta Iwaszkiewicz
Keyword(s):  
Minimally Invasive ◽  
National Park ◽  
Dry Matter ◽  
Nutritive Value ◽  
Creeping Bentgrass ◽  
Beef Cows ◽  
Agrostis Stolonifera ◽  
Dry Matter Intake ◽  
Herbage Intake ◽  
Invasive Method

The aim of the study was to evaluate herbage dry matter intake in 16 beef cows which grazed continuously on permanent pastures within the “The Warta Estuary” National Park (Poland), using the minimally invasive method based on <em>n</em>-alkanes as markers (C<sub>29</sub>, C<sub>31</sub>, C<sub>33</sub>). Significant differences were observed in the nutritive value of herbage collected for analyses by cutting or nipping. The calculated content of energy and protein in the nipped herbage was higher: UFL by 58.1% and PDI by 50%, with a higher digestibility of nutrients. The values obtained for DM intake in pasture herbage by cows were closest to the standards when calculations were based on the C<sub>29</sub>/C<sub>32</sub> pair of <em>n</em>-alkanes. However, the best prediction of DM intake estimation from creeping bentgrass (<em>Agrostis stolonifera</em>) pasture, in agreement with the accepted energy and protein standards, was based on the proportions between alkanes C<sub>31</sub>/C<sub>32</sub>.

Constraints to the modelling of diet selection and intake in the grazing ruminant

1996 ◽  
Vol 47 (2) ◽  
pp. 257 ◽  
Author(s):  
H Dove
Keyword(s):  
Decision Support ◽  
Diet Selection ◽  
Point Of View ◽  
Botanical Composition ◽  
Factors Influencing ◽  
Major Constraint ◽  
Physical Chemical ◽  
Herbage Intake ◽  
Spatial Terms ◽  
Future Work

The interaction of grazing animals and their pasture generates substantial income for Australia, so that an interest in modelling the processes involved can be justified readily. Based on a brief review of the factors influencing diet selection, it is suggested that, from the point of view of modelling the process, a major constraint has been the availability of accurate and convenient methods for estimating the botanical composition of the consumed diet. It is also suggested that there is a need in future work to define more adequately the available herbage in botanical, physical, chemical and spatial terms, and to conduct experiments in which factors influencing selection are examined in an unconfounded way. It is further suggested that, while the idea of fixed preference or selection coefficients for particular species is attractive from a modelling standpoint, available evidence does not support the concept. Factors influencing herbage intake are then discussed, particularly in relation to the interaction between the degree of rumen fill and the animal's capacity to use energy. The manner in which this interaction has been used in the modelling of intake is then described briefly and the modeling of diet selection and intake within the decision-support system GrazFeed is presented by way of example. Finally, the constraints associated with model validation are discussed briefly, especially in relation to the need in future work to define more adequately the characteristics of the pasture on offer.

Seasonal changes in the nutritive value of grass species in Spinifex pastures of Western Australia.

1988 ◽  
Vol 10 (1) ◽  
pp. 60 ◽  
Author(s):  
AM Holm ◽  
RJ Allen
Keyword(s):  
Western Australia ◽  
Nutritive Value ◽  
Grass Species ◽  
In Vitro Digestibility ◽  
Gulf Region ◽  
Plant Parts ◽  
The Common ◽  
Exmouth Gulf

This study was undertaken to assess whether the nutritional quality of spinifex pasture lands is improved by buming to promote the growth of grasses other than spinifex. We selected two comparable sites in the Exmouth Gulf region of Western Australia; one had been bumt in late 1979 and the other had not been burnt for many years. On these sites we sampled the five grass species present, as well as Triodia pungens (soft spinifex) and Plectrachne >chinzii (Oat eared spinifex) on 10 occasions from March 1980 to April 1982. Plant parts were analysed for nitrogen, phosphorus and sulphur content, and in vitro digestibility. None of the common grass species tested was more nutritious or more palatable than soft spinifex. It seems that little is gained from manipulating spinifex pastures through burning if the aim is to encourage alternative grass species. There is a need however for further studies into the importance of woody herbs and forbs in the nutrition of grazing animals on spinifex country and the effect of fire on these species.

Effect of species, plant part, and season of harvest on n-alkane concentrations in the cuticular wax of common rangeland grasses from southern Africa

2001 ◽  
Vol 52 (9) ◽  
pp. 875 ◽  
Author(s):  
D. G. Smith ◽  
R. W. Mayes ◽  
J. G. Raats
Keyword(s):  
Southern Africa ◽  
Diet Composition ◽  
Common Species ◽  
Flower Head ◽  
Grass Species ◽  
Wet Season ◽  
Reliable Technique ◽  
Plant Parts ◽  
Plant Samples ◽  
Whole Plant

The use of plant alkane concentrations to measure diet composition of herbivores has been shown to be a reliable technique in animals grazing temperate, sown pastures that contain a relatively small number of plant species. There is potential to develop this technique for use with free-range animals foraging upon species-rich rangeland. In order for the technique to be effective, the alkane concentration patterns (ACP) of the component species of the diet must be distinct from one another. Common species of grasses from southern Africa were analysed for their alkane concentrations in order to evaluate the use of the alkane technique for measuring diet composition under complex rangeland conditions. The alkane profiles were determined in different plant parts from 40 grass species gathered during the wet season and 23 gathered during the dry season. Statistical analysis, using ANOVA, showed that there were highly significant differences (P < 0.001) in the C 25, C 27 , C 29 C 31 , C 33 , and C 35 alkane concentrations between flower head and stem during both the dry and wet seasons. Similar statistical differences were apparent in the C 25 , C 27 , C 29 , and C 31 alkane concentrations of leaf and stem during both seasons; differences in C 33 and C 35 concentrations were significant but at a lower level (P < 0.01 and P < 0.05, respectively). Differences in C 25 , C 27 , and C 29 alkane concentrations between flower head and leaf were only significant (P < 0.001) during the wet season. Statistical differences (P < 0.001) between whole plant samples obtained in different seasons were due to changes in the proportion of flower head, leaf, and stem. Cluster analysis often showed less similarity between plant parts of the same species than between whole plant samples of different species. It was concluded that ACPs measured in the selected species were probably too similar and thus, plants could not be identified using the alkane technique. However, it was possible to use the alkane technique to determine the proportions of flower-head, leaf, and stem in the diet.

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