Grazing pressure and tree competition affect cattle performance and native pastures in Eucalypt woodlands of Queensland, north-eastern Australia

2020 ◽  
Vol 60 (7) ◽  
pp. 953
Author(s):  
Trevor J. Hall ◽  
Richard G. Silcock ◽  
David G. Mayer
Keyword(s):  
Body Condition ◽  
High Pressures ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Pasture Production ◽  
Eastern Australia ◽  
North Eastern ◽  
Eucalypt Woodlands ◽  
Native Pastures ◽  
Grazing Pressures

Context Well managed grazing pressure will optimise animal and pasture production, and preserve the soil to maintain a viable beef business on native pastures in eucalypt woodlands. Aims A cattle grazing experiment was established to measure animal and pasture performance under management practices used in the Aristida/Bothriochloa native pastures in central Queensland. Methods Performance of Brahman-cross steers and pastures were measured in an experiment with three grazing pressures by two tree densities in a Eucalyptus populnea woodland in north-eastern Australia over 8 years in paddocks of 4–18 ha. Key results At low grazing pressure with trees killed by herbicide (‘cleared’), stocking rate increased 35% as pasture composition and biomass improved over 8 years. At low grazing pressure where treed, stocking rate remained constant, however, at high grazing pressure where treed, it was reduced after 4 years. The annual liveweight gain increased from 0.37 to 0.45 to 0.51 kg/head.day as grazing pressure was reduced from high to medium to low grazing pressure respectively, and across grazing pressures it decreased from 0.49 where cleared to 0.39 kg/head.day where treed. Liveweight gain per hectare increased under low grazing pressure and declined at medium and high pressures. Body condition scores responded positively to lower grazing pressure and a lack of tree competition to pastures. This treatment combination also produced higher animal sale values. Pasture biomass, basal area and ground cover were all affected negatively by increasing grazing pressure. Conclusions Grazing 25% of autumn pasture improved dry matter production, species composition and land condition, and increased steer growth rates, body condition and their market value. This grazing pressure produced an increasing trend in stocking rates relative to the decline at higher grazing pressures. Higher liveweight gain/ha was produced initially at high grazing pressure (75% utilisation), however, after 4 years animal condition and pastures deteriorated, requiring a reduction in stocking rate to maintain the condition of both the remaining animals and the pastures. Managing tree competition to pastures is necessary to maintain the higher animal production potential. Implications This objective information demonstrates the benefits for cattle, pastures and long-term economic outcomes of managing for conservative grazing pressure and controlling tree competition to pasture in this woodland. Applying these findings can improve beef business outcomes and provide management groups with objective educational resources.

Grazing pressure impacts on two Aristida/Bothriochloa native pasture communities of central Queensland

2017 ◽  
Vol 39 (3) ◽  
pp. 227 ◽  
Author(s):  
Trevor J. Hall ◽  
Paul Jones ◽  
Richard G. Silcock ◽  
Piet G. Filet
Keyword(s):  
Ground Cover ◽  
Predictive Modelling ◽  
Grazing Pressure ◽  
Total Contribution ◽  
Themeda Triandra ◽  
Crown Cover ◽  
Economic Production ◽  
Eastern Australia ◽  
Negative Effect ◽  
Native Pastures

Managing native pastures for sustainable and economic production requires a good understanding of grazing effects on pasture dynamics. The Aristida/Bothriochloa pastures of north-eastern Australia are important for cattle production but little data on grazing pressure impacts on pastures are available to guide management decisions of producers, for land management education programs, or for predictive modelling. To address this deficiency, four different continuous grazing intensities were imposed on woodland communities over 7 or 8 years at two sites: a Eucalyptus populnea (poplar box) and a E. melanophloia (silver-leaved ironbark) community. Both sites had replicated paddocks grazed at a low, medium or high grazing pressure by +/− tree killing using herbicide (12 paddocks), and 12 ungrazed (nil grazing pressure) 1-ha plots subjected to the same tree-killing contrasts. Grazed paddock areas were fixed and varied between 3.5 and 21.5 ha. Differential grazing pressures were reset each autumn, by adjusting cattle numbers to consume over the next year the equivalent of 0%, 25%, 50% or 75% of the standing pasture mass available. Pasture grasses suitable as indicators of grazing pressure were identified for both communities. Under low grazing pressure, Themeda triandra (kangaroo grass) was the only desirable grass to show a significant increase in total contribution over time at both sites, although Dichanthium sericeum (Queensland bluegrass) also increased its contribution at the poplar box site. Chloris species increased their contribution as grazing pressure increased. The proportion of less palatable Aristida spp. (wiregrasses) in the pasture was not affected by high grazing pressure, although they increased at low grazing pressure in the poplar box community. There were no consistent changes in native legumes or weedy forb species to any treatment. Increasing grazing pressure had a greater negative effect on pasture mass, ground cover and pasture crown cover area than on changing species composition. Most changes in composition due to grazing pressure were smaller than those associated with variable seasonal rainfall, and were greater in the poplar box community. In above-average rainfall years grazing up to 50% of autumn standing pasture mass had no detrimental effect on composition in treeless poplar box country in the short term. The pastures remained stable or improved in both communities when grazing pressure was set annually to utilise 25% of the standing autumn forage.

Seed coating and localized application of phosphate for improving seedling growth of grasses on acid, sandy red earths

1982 ◽  
Vol 33 (5) ◽  
pp. 785 ◽  
Author(s):  
RG Silcock ◽  
FT Smith
Keyword(s):  
Seedling Growth ◽  
Surface Soil ◽  
Water Soluble ◽  
Phosphate Fertilizers ◽  
Eastern Australia ◽  
Close Proximity ◽  
North Eastern ◽  
Reasonable Cost ◽  
Phosphorus Sources ◽  
Native Pastures

The seedling growth of tropical grasses on acidic, sandy red earths was improved greatly by the application of small amounts of phosphate fertilizers in close proximity to the seed. Fertilizer had to be applied within 5 cm of the seed of Anthephora pubescens to have any effect. Many phosphorus sources stimulated seedling growth of Cenchrus ciliaris when applied as coatings to the fascicle (the propagule containing the grain). Water-soluble orthophosphates proved the best phosphorus sources for the purpose. Optimum rates of coating ranged up to 2 mg phosphorus per fascicle (10 mg monosodium phosphate), depending on the availability of surface soil moisture. Valuable grasses such as C. ciliaris could be introduced into millions of hectares of native pastures on infertile, sandy soils in north-eastern Australia, at reasonable cost, if a suitable commercial coating process can be developed.

Germinable soil seed banks in native pastures in north-eastern Australia

1994 ◽  
Vol 34 (8) ◽  
pp. 1113 ◽  
Author(s):  
JG McIvor ◽  
CJ Gardener
Keyword(s):  
Seed Banks ◽  
Perennial Grasses ◽  
Soil Seed Banks ◽  
Eastern Australia ◽  
North Eastern ◽  
Small Seed ◽  
Annual Grasses ◽  
Native Pastures ◽  
Total Seed ◽  
Tussock Grasses

Germinable soil seed banks were determined in 20 native pasture communities of widely varying composition (dominated by native tussock grasses, Bothriochloa pertusa, or forbs) near Collinsville (20�34'S, 147�51'E). Samples of surface soil (0-10 cm) were taken during the late dry season, seeds were germinated in a shadehouse, and seedlings were identified and counted. Over all pastures there were seeds of 100 species in the seed banks, including 29 grasses (14 perennial), 11 legumes, 8 sedges, and 52 forbs. Total seed numbers varied among pastures from 210 to 9770/m2. Forbs were the most numerous component, followed in order by sedges, perennial grasses, annual grasses, and legumes. Of the 790 seeds/m2 of perennial grasses, the naturalised species B. pertusa contributed 620/m2. Even though the native perennial grasses were prominent in these pastures, they had few seeds in the soil, especially when the pastures had been heavily grazed. To maintain these grasses in pastures, management should aim to prevent excessive mortality of the perennial plants as seedling regeneration could be limited by the small seed numbers available.

Influence of stocking rate and mixed grazing of Angora goats and Merino sheep on animal and pasture production in southern Australia. 3. Mohair and wool production and quality

2010 ◽  
Vol 50 (3) ◽  
pp. 168 ◽  
Author(s):  
B. A. McGregor
Keyword(s):  
Growth Rate ◽  
Fibre Diameter ◽  
Fibre Production ◽  
Grazing Pressure ◽  
Stocking Rate ◽  
Pasture Production ◽  
Merino Sheep ◽  
Wool Production ◽  
Temperate Pastures ◽  
Angora Goats

The effects of animal species (AS; Angora goats, Merino sheep, mixed-grazed goats and sheep at the ratio of 1 : 1) and stocking rate (SR; 7.5, 10 and 12.5 animals/ha) on fibre production and quality were determined in a replicated experiment on improved annual temperate pastures in southern Australia from 1981 to 1984. Separately grazed sheep produced the most total clean fibre/ha at each SR. Mixed-grazed treatments produced amounts of clean fibre/ha similar to the arithmetic mean of sheep and goat treatments at 7.5/ha (21.9 versus 21.3 kg/ha), 10% more at 10/ha (28.3 versus 25.3 kg/ha, P < 0.05) and 7% more at 12.5/ha (31.6 versus 29.6 kg/ha, P < 0.10). Clean wool production/head was affected by AS and SR but not year. Clean mohair production was affected by SR and year but not AS. Variation in mean fibre diameter (MFD) accounted for 67 and 71%, respectively, of the variation in clean wool and clean mohair production/head. There was an AS × SR interaction for clean fibre production/t pasture. Growth rate of mohair was highest in autumn and least in summer. In each season, an increase in the SR reduced the clean mohair growth rate. Growth rate of wool was highest in spring and least in summer. Wool and mohair MFD were affected by an AS × SR interaction. Mohair MFD was also affected by year and season. At 10/ha, wool from mixed-grazed sheep had a greater MFD than wool from separately grazed sheep (20.2 versus 18.9 μm) and mixed-grazed goats grew mohair 1 μm coarser than separately grazed goats. At 12.5/ha mixed-grazed goats grew mohair 1.9 μm finer than separately grazed goats. Mohair MFD was predicted by a multiple regression that included average liveweight for the period of fleece growth, season of growth (summer 1 µm finer than winter) and year (range 1.27 µm). Mohair MFD increased 4.7 µm/10 kg increase in average fleece-free liveweight (P = 6.4 × 10–14). Fleece-free liveweight alone accounted for 76.4% of the variation in mohair MFD. There was an AS × SR interaction for the incidence of kemp and medullated fibres; under severe grazing pressure their incidence was suppressed. This experiment indicated that the principles associated with the effects of SR on wool production on annual temperate pastures apply to mohair production. Mixed grazing of Merino sheep and Angora goats produced complementary and competitive effects depending on the SR. Angora goats should not be grazed alone or mixed-grazed with sheep on annual temperate pastures at SR greater than that recommended for Merino sheep.

Forage quality and feed intake responses of cattle to improved pastures, tree killing and stocking rate in open eucalypt woodlands of north-eastern Australia

1998 ◽  
Vol 131 (2) ◽  
pp. 211-219 ◽  
Author(s):  
A. J. ASH ◽  
J. G. McIVOR
Keyword(s):  
Diet Quality ◽  
Feed Intake ◽  
Nitrogen Concentration ◽  
Forage Quality ◽  
Experimental Period ◽  
Stocking Rate ◽  
Animal Performance ◽  
Eastern Australia ◽  
North Eastern

The effects of oversowing introduced grasses and legumes, tree killing and stocking rate on simulated diet quality and feed intake of cattle were studied in an open eucalypt woodland in the semi-arid tropics of north-eastern Australia in 1990. Rainfall during the experimental period was above average, producing good conditions for pasture growth, which resulted in little influence of stocking rate on pasture or dietary attributes. During the growing season, forage quality, as measured by nitrogen concentration and in vitro digestibility, was higher in sown pasture than in native pasture, and higher in plots with live trees than in plots with killed trees. Treatment differences in herbage quality disappeared later in the year when pastures senesced. In sown pasture treatments, there was no effect of tree killing on legume (Stylosanthes spp.) quality. However, Stylosanthes made a greater contribution to the diet of cattle grazing in wooded paddocks than in paddocks where trees had been killed. The proportion of Stylosanthes in the diet reached a peak in May and then declined. Oversowing increased both diet quality and feed intake while, to a lesser extent, killing trees resulted in generally lower diet quality and feed intake.Estimates of liveweight change were made from the quantities of energy and protein consumed by the cattle. As expected, large increases in liveweight gain were predicted to occur in oversown pastures compared with native pastures. However, estimates indicated that animal performance may be better where trees are left intact rather than killed. While carrying capacity is greatly increased with the removal of trees, this may be at the expense of individual animal performance. Possible reasons for this significant negative response in dietary attributes and predicted liveweight gain to tree killing are discussed.

Addressing on-farm management to enhance pasture productivity and persistence

2013 ◽  
pp. 241-244
Author(s):  
W.N. Reynolds
Keyword(s):  
Management Strategies ◽  
Dairy Farm ◽  
Stocking Rate ◽  
Pasture Management ◽  
Pasture Production ◽  
Operating Profit ◽  
The North ◽  
The Cost ◽  
On Farm ◽  
Attention To Detail

Following the 2007/08 drought, we experienced poor pasture production and persistence on our dairy farm in north Waikato, leading to decreased milksolids production and a greater reliance on bought-in feed. It is estimated that the cost of this to our farming operation was about $1300 per hectare per year in lost operating profit. While climate and black beetle were factors, they did not explain everything, and other factors were also involved. In the last 3 years we have changed our management strategies to better withstand dry summers, the catalyst for which was becoming the DairyNZ Pasture Improvement Focus Farm for the north Waikato. The major changes we made were to reduce stocking rate, actively manage pastures in summer to reduce over-grazing, and pay more attention to detail in our pasture renewal programme. To date the result has been a reduced need for pasture renewal, a lift in whole farm performance and increased profitability. Keywords: Focus farm, over-grazing, pasture management, pasture persistence, profitability

Grazed pasture parameters. I. Pasture dry-matter production and availability in a stocking rate and grazing management experiment with dairy cows

1966 ◽  
Vol 67 (2) ◽  
pp. 199-210 ◽  
Author(s):  
A.G. Campbell
Keyword(s):  
Dairy Cow ◽  
Dry Matter ◽  
Grazing Management ◽  
Dry Matter Production ◽  
Small Scale ◽  
Stocking Rate ◽  
Rotational Grazing ◽  
Pasture Production ◽  
Grazed Pasture ◽  
Matter Production

1. Net pasture dry matter production and available pasture dry matter were measured over 3 years in a small-scale replica of the study of the effects of dairy cow grazing management and stocking rate reported by McMeekan & Walshe (1963).2. The four treatments were(i) Controlled rotational grazing, light stocking rate (0.95 cows/acre).(ii) Controlled rotational grazing, heavy stocking rate (1.19 cows/acre).(iii) Uncontrolled, set stocked grazing, light stocking rate (0.95 cows/acre).(iv) Uncontrolled, set stocked grazing, heavy stocking rate (1.19 cows/acre).3. The pasture measurement technique employed measured net pasture production (gains through new growth minus losses from all sources). It is argued that this parameter, rather than absolute pasture production, governs the changes in the dry matter feed supply to the grazing animal.

The effects of grazing on the phosphorus requirement of an annual pasture

1971 ◽  
Vol 22 (1) ◽  
pp. 81 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Subterranean Clover ◽  
Growing Season ◽  
Maximum Growth ◽  
Grazing Pressure ◽  
Light Interception ◽  
Botanical Composition ◽  
Stocking Rate ◽  
Phosphorus Requirement ◽  
Root Size

The applied phosphorus requirement of a pasture sown to subterranean clover was measured with and without grazing. Under moderate grazing pressure, in the year of establishment, the pasture required about 50 % more phosphorus than when ungrazed. In the following season, at a higher stocking rate, the grazed areas needed twice as much phosphorus as the ungrazed to make 90% of their maximum growth. In both years this difference in requirement between stocked and unstocked treatments was present throughout the growing season. Increased phosphorus requirement under grazing is associated with the need for greater uptake of phosphorus under conditions where redistribution of absorbed phosphorus within the plant is prevented by defoliation. It does not appear to be due to effects of defoliation on root size. Nor does it depend on differential light interception or on changes in botanical composition.

Beef production from native pastures sown to fine-stem stylo in the Burnett region of south-eastern Queensland

1979 ◽  
Vol 19 (97) ◽  
pp. 140 ◽  
Author(s):  
EJ Bowen ◽  
KG Rickert
Keyword(s):  
Stocking Rate ◽  
Management Options ◽  
North West ◽  
Heteropogon Contortus ◽  
South Eastern ◽  
Continuous Grazing ◽  
Weight Gains ◽  
The Mean ◽  
Native Pastures ◽  
Stocking Rates

At Gayndah, south-eastern Queensland, a native Heteropogon contortus pasture, sown to fine-stem stylo (Stylosanthes guianensis var. intermedia), and invaded by red natal grass (Rhynchelytrum repens), was grazed by weaner steers from June 1 in three treatments : heavy and light put-and-take grazing for five years from 1971, and set-stocked at 1.37 animals ha-1 for two years from 1974. Weight gains in the put-and-take treatments were not significantly different. The mean annual liveweight gain was 167 kg animal-1 at a mean equivalent stocking rate of 1.47 animals ha-1. Over the same period unsown native pasture, cleared of timber, gave a gain of 62 kg animal-1 at 0.62 animals ha-1. In all seasons except summer, weight gains declined linearly with stocking rate and in 1972-73, with a mean equivalent stocking rate of 2.66 animals ha-1, the annual gain was almost halved. When equivalent stocking rates were 0.9, 0.9, 1.8 and 1.2 animals ha-1 in winter, spring, summer and autumn, the respective gains were 4, 73, 65 and 45 kg animal-1. The set-stocked treatment had a mean annual gain of 147 kg animal-1. At another site 116 km north-west of Gayndah, two paddocks of Heteropogon contortus and fine-stem stylo were set-stocked with weaners over four years. One paddock had four applications of superphosphate of 250 kg ha-1. The mean annual liveweight gains were significantly different, being 154 and 143 kg animal-1 in the fertilized and unfertilized paddocks at mean stocking rates of 0.83 and 0.74 animals ha-1, respectively. In a grazing protection experiment the density of fine-stem stylo declined exponentially with an accumulation of pasture dry matter in spring and summer. Heavy continuous grazing, an annual hay cut and an accidental fire all increased the density of fine-stem stylo. Management options to maintain the density of fine-stem stylo and the relative importance of the legume and grass to animal production are discussed.

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