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Field experiments were carried out at seven sites in southern Australia from 2002 to 2006 to measure changes in plant frequency, root characteristics and summer activity for a range of grass and herb species or cultivars. Annual rainfall during the experimental period was on average 75 mm lower than the long-term average. Plant frequency differed significantly between species and between sites. Temperate grasses generally had higher frequencies than subtropical grasses, native grasses and herbs. Cocksfoot (Dactylis glomerata cvv. Currie, Porto), tall wheat grass (Thinopyrum ponticum cv. Dundas), winter-active tall fescue (Festuca arundinacea cvv. Fraydo, Resolute MaxP) and phalaris (Phalaris aquatica cvv. Atlas PG, Australian) were the most persistent of the temperate perennial species over the experimental period. The frequency of most cultivars declined from year 2 to year 4 after establishment, but the frequency of kikuyu (Pennisetum clandestinum cv.Whittet) and wallaby grass (Austrodanthonia richardsonii cv. Taranna) increased by over 5% from year 2 to year 3, and cocksfoot (cv. Currie) increased from year 3 to year 4. At two sites where measurements were made, there were significant differences in rooting depth between species. Whittet kikuyu was the deepest among all species with a rooting depth of up to 2 m, followed by phalaris, tall fescue, grazing brome (Bromus stamineus) and tall wheat grass. Root density was affected by plant genotype and soil structure. Root density of the species varied significantly in the subsoil (0.1–1.1 m) and deeper subsoil (1.1–2 m) but not in the topsoil (0–0.1 m). Green-leafiness over summer was generally higher for subtropical grasses, native grasses, herbs and some summer-active temperate grasses, than most temperate grasses with high summer dormancy.

This study reports on the effect of oversowing perennial ryegrass (Lolium perenne L.) into a degraded perennial ryegrass and white clover (Trifolium repens L.) pasture to extend its productive life using various intensities of seedbed preparation. Sites in New South Wales (NSW), Western Australia (WA), South Australia (SA) and Tasmania (Tas.) were chosen by a local group of farmers as being degraded and in need of renovation. Control (nil renovation) and medium (mulch and graze, spray with glyphosphate and sow) renovation treatments were common to all sites whereas minimum (mulch and graze, and sow) and full seedbed (graze and spray with glyphosphate and then full seedbed preparation) renovation were imposed only at some sites. Plots varied in area from 0.14 to 0.50 ha, and were renovated then sown in March or April 2000 and subsequently grazed by dairy cows. Pasture utilisation was estimated from pre- and post-grazing pasture mass assessed by a rising plate pasture meter. Utilised herbage mass of the renovated treatments was significantly higher than control plots in period 1 (planting to August) and 2 (first spring) at the NSW site only. There was no difference among treatments in period 3 (first summer) at any site, and only at the WA and NSW sites in period 4 (March to July 2001) was there a response to renovation. As a result, renovation at the NSW site only significantly increased ryegrass utilisation over the whole experimental period. Ryegrass plant density was higher at the NSW, WA (excluding minimum renovation) and Tas. (excluding full renovation) sites 6 months after renovation but this was only sustained for 12 months for the minimum and medium treatments at the NSW and Tas. sites, respectively, presumably due to reduced competition from naturalised C4 summer grasses [kikuyu (Pennisetum clandestinum) and paspalum (Paspalum dilatatum)] in NSW. At the NSW, WA and SA sites, the original ryegrass plant density was low (

Two experiments were undertaken to examine the effects of supplement grain type (barley v. maize) and level of feeding [4.5 v. 8.1 kg dry matter (DM)/cow.day] on the milk production, nutrient intake and rumen fermentation of cows grazing swards of biennial ryegrass (Lolium multiflorum cv. Concord), prairie grass (Bromus willdenowii cv. Matua) (expt 1) or kikuyu (Pennisetum clandestinum cv. Common) (expt 2). There were no interactions (P>0.05) between grain type and level of feeding (G × L) on milk production, liveweight change or condition score in either experiment. When the main effects were examined, feeding maize as opposed to barley resulted in higher milk protein concentrations (P = 0.001) in both experiments (2.96 v. 2.83% and 2.91 v. 2.71% for expts 1 and 2, respectively), higher milk fat concentration (P = 0.001; 3.85 v. 3.36%) and daily milk fat yield per cow (P = 0.029; 875 v. 791 g) in experiment 1, and higher daily yield (P = 0.004) of milk protein in experiment 2 (618 v. 578 g). In both experiments, feeding increased supplement resulted in higher (P0.05) on pasture intake, neutral detergent fibre digestibility or rumen concentrations of ammonia or volatile fatty acids. There were G × L interactions on organic matter digestibility (P = 0.019) in experiment 1 and on starch digestibility (P = 0.003) in experiment 2, with cows fed 4.5 kg DM/day of barley having higher organic matter digestibility, and cows fed either level of barley having higher starch digestibility. In both experiments, feeding more supplement reduced (P>0.05) daily pasture intake per cow (13.3 v. 11.3 kg DM and 9.9 v. 8.3 kg DM for expts 1 and 2, respectively). Feeding barley rather than maize caused higher starch digestibility (P = 0.006) in experiment 1 (93.0 v. 89.8%), and higher organic matter digestibility (P = 0.021) and neutral detergent fibre digestibility (P = 0.009) in experiment 2 (70.8 v. 69.3% and 62.9 v. 59.7%, for organic matter digestibility and neutral detergent fibre digestibility, respectively). Feeding maize rather than barley reduced (P = 0.034) rumen molar proportion of butyrate (16.1 v. 17.6 mol %) in experiment 1. These experiments show that feeding supplements based on maize, as opposed to barley can: increase the milk fat concentration and yield of cows grazing temperate pastures; increase the milk protein yield of cows grazing tropical pastures; and increase the milk protein concentration of cows grazing either temperate or tropical pastures.

The use of legume crops as alternatives to a fallow in wheat–maize rotations in the Rift Valley of Kenya may suppress weeds and add nitrogen to the system. A field study was set up in the Njoro and Rongai regions to evaluate the effect of managing the traditional fallow with chickpea (Cicer arietinum L.), field bean (Phaseolus vulgaris L.), soybean [Glycine max (L.) Merril], field pea (Pisum sativum L.) and dolichos [Lablab purpureus (L) Sweet] on the following wheat and maize crops. The objectives of this study were to assess the impact of improved fallow on weed control, soil nitrogen and performance of the following cereals in a bid to improve their yields. The legumes, along with wheat and maize, were grown as fallow-management treatments during the short-rains season, and their residues were incorporated into the soil before sowing the test cereal in the long-rains season. Weed biomass and species diversity reduced by 35–92% and 25–58% at Njoro, and 10–100% and 83–100% at Rongai, respectively, in the succeeding cereal against preceding traditional fallow. The perennial weeds, which included Digitaria scalarum, Pennisetum clandestinum and Conyza sp., were substantially reduced in the managed fallow. Legume-managed fallow significantly improved soil nitrogen status and the yield of the following cereals. Grain yield in managed fallow increased on average by about 39 and 17% over locations in maize and wheat, respectively. Despite yielding less soil-incorporated residue, the impact of legumes was greater than that of the traditional fallow yielding large amount of organic material. Among the legume species, dolichos showed outstanding positive effect on succeeding cereal crop, probably due to increased soil nitrate levels. Field bean and chickpea have a potential seed advantage, although the latter is susceptible to 100% loss by Helicoverpa armigera. Hence, managing the traditional short-rains fallow with legumes could reduce weed infestation, in addition to improving soil nitrogen for subsequent crops.

Thirty perennial grass accessions were evaluated for emergence, growth and persistence at 6 severely salinised seepage scalds on the western slopes of New South Wales. Warm-season accessions were sown or planted in spring 1996 and 1997, and cool-season types in autumn 1996 and 1997. Control species, tall wheat grass (Thinopyrum ponticum) and puccinellia (Puccinellia ciliata) were sown in spring and autumn. Plants were monitored over 2 growing seasons. None of the accessions, including the controls, performed well at all sites. Of the accessions established from seed, tall wheat grass was the most reliable in terms of the number of successful establishments but its growth potential was only achieved at a few sites. Some warm-season species (Panicum coloratum, Chloris gayana and Cynodon dactylon) approached their growth potential at some sites but overall rates of establishment were very low. The performance of puccinellia appeared to be adversely affected by low pH. It was concluded that on severely scalded sites, vegetative propagation of stoloniferous–rhizomatous plants, e.g. Pennisetum clandestinum, Paspalum vaginatum and C. gayana, may be the best option.

Production parameters and water use of kikuyu (Pennisetum clandestinum) and annual-based pastures were monitored for a beef weaner production system from 1998 to 2000 in a paddock-scale demonstration on the south-east coast of Western Australia. A paired paddock (40–105 ha) comparison was carried out between a kikuyu-based pasture (DSKikuyu) and temperate annual pasture (DSAnnual), with comparative measurements covering pasture production, composition and quality, and soil water deficits and drainage. The stocking rates for the paddocks were determined by the pasture productivity and cow P8 fat depth in the 'lactation phase' (April–December), and by sward management and soil stability imperatives in the 'dry cow phase' (January–March). Cow liveweight and P8 fat depth and calf liveweight were compared during the 'lactation phase'. Kikuyu and annual pasture had similar carrying capacities through the 'lactation phase'. Kikuyu pasture carried more animals than annual pasture through the 'dry cow phase' (late summer and autumn) in all years. During late autumn, cattle were destocked from the annual pasture to reduce the risk of wind erosion and 'crash grazed' on the kikuyu pasture so as to reduce competition between kikuyu and regenerating annual grass and legume species. The comparative quality and productivity of the kikuyu pasture in the lactation phase (winter and spring) was positively correlated with the level of winter legume present. When a similar level of winter legume was measured in the kikuyu pasture relative to the annual pasture (in 1998), the pasture quality, cow liveweight and condition and calf weaning weights were all comparable between the 2 pasture types. When a low legume component was recorded in the kikuyu pasture, the pasture quality and cow liveweight and condition were poorer than the annual pasture. The kikuyu pasture growing on deep sandy soil developed a larger (mean 37 mm) soil water deficit than the annual pasture over the measurement period, and in particular from November to March. When integrated over a farm where kikuyu covers 40% of the total area, as was the case in this experiment, the resulting deep drainage was calculated to be just over half that of an equivalent whole farm of annual pasture. Over the 3 years of monitoring, the combined system of annual and kikuyu pasture was calculated to have an annual gross margin 19% higher than the annual pasture alone. The major source of difference was no requirement for supplementary feed in the kikuyu–annual pasture system. This difference was limited however, by lighter post-weaning sale weights of cull cows from the kikuyu pasture in 'poor legume' years. There was no difference of calf weaning weights between treatments.There is considerable opportunity to improve on this gross margin, through achieving a consistent strong presence of legume in the kikuyu pasture through winter and spring.

The effect of Tasmanian blue gum (Eucalyptus globulus) belts and kikuyu (Pennisetum clandestinum) grass on livestock production and groundwater recharge was studied in the high rainfall zone (>600 mm/year) of south-western Western Australia from 1998 to 2001. The objective was to identify optimum combinations of tree belts and pasture for sustainable livestock production and the prevention of secondary salinisation. Treatments were annual pasture, in competition with trees at different orientations (east, west and south), kikuyu pasture in competition with trees at one orientation (west), compared with pasture in the absence of tree competition. Plots had 0, 20 or 36% of their area within 10 m of the tree belt where tree–pasture competition would be expected. Plots (0.48 ha) were stocked with Merino wether hoggets at 12 DSE/ha on annual pastures and 14 DSE/ha on kikuyu pastures. Additional sheep were placed on plots in spring and the annual pasture was destocked in autumn.Within the growing season, herbage mass was similar across both control treatments as a result of varying stock numbers. However, in summer and autumn the kikuyu control contained between 350 and 4900 kg DM/ha more herbage than the corresponding annual pasture. While both pastures accumulated similar amounts of herbage in 1998 and 2000, kikuyu accumulated more in 1999 (11 900 v. 9800 kg DM/ha) as a result of summer rain. Competition from tree belts significantly reduced adjacent annual pasture herbage accumulation (16% average reduction), although there was no difference among the levels of competition. Trees did not significantly affect adjacent kikuyu pasture herbage accumulation. Both carrying capacity and clean wool production per hectare were significantly higher on kikuyu pasture in 1999 and 2000. Tree competition also significantly reduced the carrying capacity of neighbouring annual and kikuyu pasture by an average of 10%. Clean wool production per hectare was significantly lower on annual pasture in combination with trees (11% reduction on average), but there was less effect of competition on kikuyu pasture. The kikuyu pasture used 115, 57 and 132 mm more water than the annual pasture in 1999, 2000 and 2001, respectively. The soil water deficit beneath the trees exceeded that below both control pastures by between 297 and 442 mm.Although the addition of tree belts to annual pasture provided substantial reductions in groundwater recharge, producers would also have to accept losses in livestock production. While kikuyu alone provided significant increases in livestock production and substantial reductions in groundwater recharge, the best compromise was kikuyu in combination with tree belts.

A series of experiments was conducted to test the hypothesis that ‘synchronising’ the availability of carbohydrate and nitrogen (N) in the rumen of sheep, either by the feeding of carbohydrate-based supplements in relation to pasture intake or by provision of pasture with a higher ratio of these 2 nutrients, would benefit microbial protein synthesis (MPS). The response variables were rumen pH and ammonia (NH3), and urine allantoin was measured as an indicator of MPS. The animals used were adult castrate male sheep fitted with a rumen cannula. In experiment 1, rumen NH3 and pH were found to be at a maximum and minimum, respectively, 1–2 h after feeding kikuyu (Pennisetum clandestinum) grass and 3–4 h after feeding biennial ryegrass (Lolium multiflorum) with rumen N degradability (at 18 h in sacco) being 55 and 75%, respectively. In experiment 2, the infusion of sucrose at 4 h post-ingestion of ryegrass pasture (the anticipated time of peak rumen NH3 concentration) lowered peak NH3 concentration by 40 mg/dL (from 187 to 147 mg/dL) and raised urine allantoin excretion from 6.0 to 9.0 mmol/sheep.day compared with infusion of sucrose at –1, +1 or +7 h. When sucrose was infused, 1 h after being fed kikuyu (synchronous) at the expected time of peak rumen NH3 concentration, the NH3 peak (from 152 to 110 mg/dL) and rumen pH were reduced and urinary allantoin excretion raised (from 6.6 to 7.6 mmol/sheep.day) compared with sheep given sucrose 7 h after ingestion of kikuyu grass (asynchronous). In experiment 3, the feeding of fine-rolled barley grain at, or 2 h before, feeding kikuyu grass, to ‘synchronise’ the availability of rumen-fermentable carbohydrates (RFC) in the grain with the availability of N released from the grass, substantially reduced rumen NH3 and pH, and increased urine allantoin levels (from 10.1 to 11.8 mmol/sheep.day) compared with feeding barley at 4 or 6 h before feeding grass. In experiment 4, sheep were fed kikuyu or ryegrass cut in the early morning (AM) or late afternoon (PM), with the nutrient content varying only in water-soluble carbohydrates (64 v. 114 g/kg DM for ryegrass and 41 v. 80 g/kg DM for kikuyu, respectively) and percentage of dry matter. Sheep fed PM-ryegrass had a significantly lower rumen pH compared with sheep fed AM-ryegrass but there was no difference in rumen NH3 concentrations. Urinary allantoin secretion was substantially higher in the PM group than the AM group (8.7 v. 3.9 mmol/sheep.day). When sheep were fed PM-kikuyu the pH fell to lower values than for the AM-kikuyu (6.4 v. 6.8) and there was again no effect on rumen NH3 levels. Urine allantoin levels were higher (P = 0.006) (6.2 v. 5.6 mmol/ sheep.day) in PM-fed sheep. The results of these studies support the hypothesis that there are benefits in synchronising the availability of RFC with N in the rumen on MPS but this is not always associated with significant changes in rumen pH and NH3. The implications of these results are discussed in relation to the situation in which synchronisation of RFC and N may potentially benefit dairy cattle.

Summary. On the subtropical north coast of New South Wales, Australia, kikuyu grass (Pennisetum clandestinum), biennial ryegrass (Lolium multiflorum) and mixed perennial ryegrass (Lolium perenne)–white clover (Trifolium repens) pastures grazed by dairy cows were plucked pregrazing to simulated grazing height, every 2 weeks for 2 years to determine seasonal changes in various nutrients and in sacco organic matter and nitrogen (N) degradability. Changes in nutrients during regrowth were determined in the ryegrass component of a mixed perennial ryegrass–white clover pasture by sequentially cutting pasture at 3- or 4-day intervals to 5 cm stubble height and non-structural carbohydrates in kikuyu by cutting at 4-day intervals in February–March. There was a significant effect of season on water-soluble carbohydrate (WSC) and crude protein (CP) content of perennial ryegrass with regrowth time, resulting in an 8-fold fall in the CP : WSC ratio from the 1 to 3 leaves/tiller stage of regrowth in mid winter, a 2-fold difference in mid spring but with no discernible difference in late spring. The metabolisable energy (ME) values for biennial ryegrass exceeded 11.9 MJ/kg dry matter (DM) from July to September and then fell markedly to

Three studies were conducted to examine the production response of Friesian cows grazing well-managed lukuyu (Pennisetum clandestinum) pasture to supplementation with a cereal grain concentrate, with and without the inclusion of formaldehyde-treated protein meal. Mean (¦ s.e.) levels of nutrients in the pasture (g/kg DM) on offer were: 205 ¦ 3 crude protein; 683 ¦ 7 in vitro organic matter digestibility; 239 ¦ 2 acid detergent fibre; 615 ¦ 8 neutral detergent fibre and 4.47 ¦ 0.16, 2.51 ¦ 0.06, 31.96 ¦ 0.98, 0.39 ¦ 0.03 and 3.18 ¦ 0.09 of calcium, phosphorus, potassium, sodium and magnesium, respectively. Study 1 was a 3-farmlet study conducted over 45 days (March-April 1993) involving cows 5-6 months into lactation, which compared 3 levels of concentrate feeding at 0 (R0), 3 (R3) or 6 (R6) kg crushed barley/cow.day. Study 2 was an 18-day extension of study 1 with animals in the seventh month of lactation. The concentrate fed was 72% barley and 24% formaldehyde-treated sunflower meal. Pasture intake of individual cows was determined using an alkane technique. Mean milk yields (L/cow. day) in study 1 were 14.2, 18.3 and 18.0, and in study 2 were 12.5, 18.5 and 17.4 for treatments R0, R3 and R6, respectively. Milk fat (3.77 v. 3.26%), but not milk protein, content of the Ro cows was significantly higher than R6 cows in study 1 only. In study 2, the apparent whole-diet digestibility remained constant as concentrate level rose, indicating a negative effect of concentrate fed on forage digestibility in the absence of buffers. Study 3 was a 3 x 4 factorial design plus a 'control' group (0.5 kg barley/cow.day used as a carrier for minerals) to examine the milk production response to 3 levels of concentrate feeding (3, 6 and 9 kg/cow.day) with 4 levels of formaldehyde-treated canola meal (FTCM; 0, 20, 40 and 60% of concentrate). Rations were iso-energetic within levels of concentrates fed. The control group had significantly lower milk production (17.2 L/cow.day), as well as milk protein (2.90%), plasma urea (PU) (5.90 mmol/L) and P-hydroxybutyrate (G-OHB) (0.525 mmo1L) than other treatment groups. The mean milk production response of 0.6 L milk/kg concentrate fed in study 3 at the 3 kg/day level of feeding was lower than observed in studies 1 and 2 (1.4 and 2.0 L/kg concentrate, respectively). The level of metabolisable energy in the concentrate in study 3 had a significant influence on milk production, milk fat and milk protein levels. Plasma glucose and G-OHB levels significantly increased with the incorporation of FTCM into the concentrate. Nonesterified fatty acid levels dropped significantly below levels of other treatments at the lowest level of inclusion of FTCM. PU levels generally increased in response to increasing metabolisable energy and inclusion of FTCM in the concentrate, with an interaction between them. Milk urea (MU) levels (mmol/L) showed a significant linear (P

Two studies were conducted to compare the precision of estimating kikuyu grass (Pennisetum clandestinum) intake by Friesian cows fed 0, 3 or 6 kg of cereal-based concentrate/cow.day, using a rising plate meter (RPM), standard energy requirements in reverse (RS) and plant wax alkanes as internal markers. Study 1 compared herbage intake estimates obtained using the RPM and RS techniques over a 45-day period. RS estimates were based on the metabolisable energy (ME) of ration components derived from in vitro organic matter digestibility (OMD) values. Pregrazing calibration equations for the RPM determined at 2-weekly intervals differed significantly (P

The feasibility of estimating, with acceptable precision, temperate and tropical pasture mass in a subtropical environment was evaluated. For the tropical grasses kikuyu (Pennisetum clandestinum) and setaria (Setaria ancepts), 3 different pasture meters were calibrated against 1 of 3 dry matter (DM) estimates. Temperate pastures (predominantly Lolium perenne and Trifolium repens) were evaluated using the Ellinbank rising plate meter (RPMl) calibrated against DM to ground level. A single regression equation was developed for syegrass-white clover pasture from data pooled within season over first- and second-year swards. The s.e. of estimate (s.e.e.) for assessing tropical grass pasture mass using RPMl was similar to that for a heavier Ellinbank meter and substantially lower than that for the electronic pasture probe. Using RPMl, separate regression equations were required for early (November-February) and late (March-May) season determinations for both kikuyu and setaria. The regression equations were based on calibrations against shoot DM (>5 cm stubble height for kikuyu and 6 cm for setaria) and are only applicable to well-managed and highly utilised pastures. Calibrations of all pasture meters over all months to green DM (senescent leaf and stem removed) gave a lower s.e.e. than total DM (kikuyu 138 v. 177 kg DM/ha, n = 171; setaria 211 v. 224 kg DM/ha, n = 177) whilst shoot DM gave a more substantial reduction in s.e.e. (kikuyu 95 v. 147 kg DM/ha; setaria 140 v. 193 kg DM/ha).

A comparison was made of 9 pasture species, some of which are coming into increasing use in Australia, for potassium (K) requirements and early growth. Plants were grown in sand culture in glasshouse experiments and were provided with nutrient solutions containing 7 rates of K (0-5 mmol/L), and nitrogen (12 mmol/L). Plants were sampled twice, the second sampling coinciding with flowering of most species. Symptoms indicating K deficiency were recorded, and diagnostic indices were derived for blades and petioles of the youngest open leaves (YOL), or for youngest expanded blades, and for whole shoots. Medicago murex and M. truncatula had the highest yield at the first sampling. Pennisetum clandestinum, Phalaris aquatica, and M. polymorpha had the highest yield at the second sampling and had a lower internal requirement for K than the remaining species, while Ornithopus compressus had the lowest yield. In all species except M. murex, critical K concentrations in whole shoots declined with plant age. Only in L. pedunculatus did the use of the YOL yield similar K concentrations at the 2 samplings. Ornithopus compressus was shown to have a low requirement for K and a high K efficiency, but it also showed poor scavenging ability. All plant parts sampled could be used to discriminate between K-deficient and K-sufficient plants. Critical K concentrations were higher in petioles than in blades of the YOL and, generally, were higher in whole shoots than in blades. The critical K concentrations derived for some species were similar to critical concentrations previously reported for other members of the same genera.

The potential quality of the 6 pasture grasses Setaria sphacelata var. sericea cvv. Nandi, Kazungula and Narok and var. splendida, Digitaria eriantha ssp. pentzii (pangola grass), and Pennisetum clandestinum cv. Whittet (kikuyu grass) was assessed in terms of liveweight gain of beef cattle, using a leader and follower grazing system. Pasture management was designed to provide adequate quantities of young leaf to the leaders throughout the year. This was achieved by rotational grazing and weekly adjustment of the number of followers, depending on quantity of feed available. Annual liveweight gain of the leaders (kg/steer.year) ranged from 135 (kikuyu grass) to 159 (cv. Narok) (540-636 kg/ha.year). Differences between grasses on an annual basis and over summer were not statistically significant (P = 0.12), although significant differences in liveweight gain of leaders - - - were obtained during the winter. This was associated with differences between grasses in growth at lower temperatures, and in frost tolerance. Liveweight gain of the follower group was markedly higher for pangola grass and var. splendida (272 kg/ha.year) than for the other varieties (77-140 kg/ha.year). This difference was associated with differences in number of grazing days and in the superior liveweight gain per head of followers grazing pangola grass and splendida. Liveweight gain of leaders per annum was comparable for years 1 and 2 but fell dramatically from February to August in year 3. This was associated with high rainfall, reduced solar radiation, and a decrease in in vitro digestibility of plucked leaf of all setaria varieties but not of pangola or kikuyu grasses. The relatively low liveweight gains obtained in year 3 were not associated with any overall mineral or protein deficiency.

Fertilised pastures of 4 varieties of Setaria sphacelata (var. splendida and cvv. Nandi, Narok and Kazungula), pangola grass (Digitaria eriantha ssp. pentzii) and kikuyu grass (Pennisetum clandestinum cv. Whittet) were grazed rotationally over a 3-year period at Beerwah, south-eastern Queensland. Each variety was grazed on a 5-weekly rotation by 2 leaders for 7 days; a follower herd including 2 testers grazed the regrowth for 7 days. The numbers of followers were subjectively adjusted weekly, depending on feed available. The experiment was designed to provide adequate quantities of forage of maximum potential quality to the leaders throughout the year. There were large and frequently consistent differences between the grasses in yield and its various components, leafiness, leaf and forage density, rate of development of leaf dry matter, and time and intensity of flowering under the management system imposed. Of particular interest were the high leaf yield of Narok, high overall yield of Narok and var. splendida, low rate of development of leaf area index of pangola grass and kikuyu grass, and high forage density of kikuyu grass. These differences might be expected to have an effect on pasture quality, carrying capacity and optimal management strategy.

A group of 36 Holstein-Friesian cows in a commercial dairy herd were used to test the effects on milk yield and composition of feeding 0.5 kg/day of a rumen-inert fat supplement containing long-chain fatty acids, given in addition to their normal ration. The group was divided into early and mid lactation cows, and the effect of the supplement was evaluated over a 12-week period of grazing predominantly kikuyu (Pennisetum clandestinum) pastures. There was a non-significant (P>0.05) trend to increased milk yield for cows in mid lactation (9% or 2.8 kg milk/kg fat supplement), no response in early lactation, and an overall response of 0.8 kg milk/kg fat supplement for all cows. There was no effect (P>0.05) of fat supplement on milk components. The lack of a milk response in the early lactation group is discussed in relation to the protein content of the diet and changes in liveweight. The varied responses with stage of lactation mean that feeding systems that can easily differentiate stages of lactation for cows would be required in dairies.

Infestation of late instar larvae of Oncopera brachyphylla Turner and O. mitocera (Turner) (Lepidoptera : Hepialidae) in mixed pastures at four sites on the Atherton Tablelands of Queensland over a ten week period from September-October gave a mean reduction of 8.7 kg dry matter ha-1 larva-1 m-2. Mean larval populations at the four sites for the period were 29.6, 96.9, 85.0 and 76.4 larvae m-2. The pastures consisted of Nandi setaria (Setaria anceps cv. Nandi)-Greenleaf desmodium (Desmodium intortum cv. Greenleaf) and kikuyu grass (Pennisetum clandestinum) each at two sites.

An experiment was undertaken at Wollongbar in subtropical New South Wales in which 48 dairy cows grazed long (1 200 kg/ha of dry green leaf) or short (800 kg/ha of dry green leaf) kikuyu (Pennisetum clandestinum) pasture and had access to forage lupins (Lupinus luteus cv. Weiko III) offered at 3 levels. There were 3 experimental periods in June, July-August and September, covering the dry winter-spring in successive years. Cows grazing long pasture produced more milk that was higher in protein content and lost less liveweight than did cows on short pasture (9.60 v. 8.01 L cow-1 day-l, 3.23 v. 3.09%, and -0.20 v. -0.75 kg cow-1 day-1 respectively). Cows with access to the highest rate of forage lupins produced an additional 1.4 L cow-1 day-1, the effect being greater in June (2.5 L cow-1 day-1) than in September (0.5 L cow-1 day-1). Access to lupins also improved liveweight maintenance through winter-spring. Pasture quality remained relatively constant throughout winter-spring but lupin quality declined from high nutritive value [70% in vitro digestibility (D). 48% cell wall constituents (CWC)] while vegetative in June, to low nutritive value (56% D, 56% CWC) at podding in September. The decline in milk production response in cows with access to lupins was associated with this progressive decline in lupin quality. It was concluded that lupins have high nutritive value at the vegetative stage and that when cows grazing kikuyu pasture are given access to it milk production can increase.

Three experiments were carried out to test the hypotheses that (a) there are quantitative differences in growth rate and quality between newly registered cultivars and older cultivars in response to changes in temperature and fertility, and (b) responsiveness to temperature varies between sites because cultivars acclimatize to their current environment. Performance in simulated swards indicated that potential productivity was highest from bermuda grass (Cynodon x Burton Pearson). This was, however, a poor indicator of performance in the field, where yield of bermuda grass was depressed by weeds whereas that of kikuyu (Pennisetum clandestinum) was unaffected. In the field, a newly registered kikuyu, cv. Crofts, outyielded bermuda grass and paspalum (Paspalum dilatatum) either alone or when combined with lucerne. A further experiment compared cvv. Crofts, Whittet and common kikuyu at three levels of nitrogen at three sites. Peak growth rates were the same at all locations but Crofts outyielded the other genotypes by 60, 13 and 18% at Bega (37�S.), Camden (34�S.) and Taree (32�S.) respectively. Average growth rates varied seasonally and were correlated with temperature (r > 0.9). Analysis of temperature responsiveness (kg/ha.�C) indicated that responsiveness varied consistently between genotypes at any location. Furthermore, the base temperature (the temperature below which there was negligible growth) was the same for all genotypes at any location but it increased with increasing latitude. That is, there was a tendency to greater dormancy with increasing coldness of location. Nitrogen responsiveness was the same for all genotypes and sites. Seasonal variations in digestibility and mineral concentrations in kikuyu, bermuda grass and paspalum were similar in the field and in simulated swards; quality was the same in all kikuyu genotypes. Calcium, magnesium and nitrogen concentrations of plant tops (but not phosphorus and potassium concentrations) increased with increasing rates of application of nitrogen fertilizer.

The incidence of fireweed (Senecio lautus) in carpet grass (axonopus affinis) dominant pastures was studied in two cutting experiments and a grazing trial at the Agricultural Research Centre, Wollongbar. Experiments were conducted on pastures initially dominated by carpet grass. Lower fireweed density resulted from higher herbage production or changes in botanical composition from carpet grass to the more competitive paspalum (Paspalum dilatatum) and kikuyu grass (Pennisetum clandestinum). These changes were rapidly achieved by the application of nitrogen fertilizer. Super phosphate application and management for clover development favoured invasion by fireweed in the initial stage. Subsequently the effect of superphosphate was similar to that of nitrogen fertilizer due to the response of more productive grasses to nitrogen fixed by clover. Under grazing, the density of fireweed was increased by high stocking rates, but was reduced markedly by a change to kikuyu grass dominance even under heavy grazing. Fireweed density was negatively related to per cent kikuyu grass. The densities of fireweed measured were not high and classification of fireweed as an undesirable species in these pastures is questioned. This conclusion may not apply to areas improved with temperate pasture species or in cultivations.

Nitrogen, phosphorus and potassium concentrations were determined in plant tops harvested every four weeks from nine tropical grasses fertilized with nitrogen on ten occasions at eight week intervals. Nitrogen was applied at three rates-25, 50 and 100 kg/ha (N25, N50, N100)-on each occasion. Grasses were rain-grown without grazing at a site near Gympie with an average annual rainfall of 1160 mm. Overall, nitrogen concentration in the tops increased and potassium concentration decreased with increasing nitrogen application. Phosphorus concentrations were constant at N25 and N50, but were lower at N 100. Mean nitrogen concentration was highest at 2.4% in Pennisetum clandestinum cv. Whittet, and lowest at 1 .9% in Chloris gayana cvv. Callide and Katambora, with intermediate concentrations occurring in Digitaria decumbens, Setaria sphacelata var. sericea cv. Narok, Panicum maximum cvv. Gatton and Makueni, Brachiaria decumbens cv. Basilisk and Paspalurn plicatulum cv. Bryan. Phosphorus concentration was highest in Whittet at 0.38% and lowest in Bryan at 0.25%. Potassium concentration was highest in Whittet at 2.53% and Narok at 2.29% and lowest in Katambora at 1 .48%. The implications of these concentrations and calculated nutrient uptakes are discussed in relation to animal and plant nutrition.

In a previous study it was found that four ecotypes of hybrid Bermudagrass (Cynodon dactylon) (ecotypes 632, 692, 6389 and 719) outyielded kikuyu (Pennisetum clandestinum) and common couch (C. dactylon) at three sites in New South Wales. The relative feeding value of these grasses was compared in terms of their crude protein content and organic matter digestibility when grown for two years at Mitchells Island, New South Wales (Lat. 32�S). Over the two years, kikuyu had the highest crude protein content, averaging 124 g kg-1 compared with 11 6,115,ll 1, 103 and 108, respectively, for the ecotypes 632, 692, 6389, 719 and common couch. Mean digestibilities of ecotypes 632, 692, 6389 and 719 were 63, 60, 61 and 58% respectively, compared with 60% for kikuyu and 57% for common couch. The crude protein content and digestibility of all ecotypes tended to be highest in early spring and late autumn and lower in summer, trends which were opposite to dry matter production rates. It was concluded that the quality of hybrid Bermudagrass forage was comparable with that of other sub-tropical grasses now being used in subcoastal New South Wales. However, careful pasture management would be required to maintain herbage quality during summer.

Three experiments were conducted in which the amount of feed offered to caged sheep was varied. Fresh kikuyu grass (Pennisetum clandestinum) was fed in one experiment and hays in the other two. Within each experiment a significant correlation between dry matter digestibility and liveweight occurred; no differences were detected between the slopes found with the various diets (slope = 0.34 per cent increase in digestibility per kg liveweight). Up to 60 per cent more kikuyu grass was offered to sheep than they could consume. Over this range a significant positive correlation was found between the ratio of the unconsumed to consumed feed and digestibility. This result indicates that great care should be exercised if the results of sheep digestibility experiments are used to interpret field data.

Four ecotypes of hybrid Bermudagrass (Cynodon dactylon) were compared with common couch (C. dactylon) and kikuyu (Pennisetum clandestinum) at five sites in coastal districts of New South Wales. The sites were Grafton and Coaldale (Lat. 30�S), Mitchells Island (Lat. 32�S) and Richmond and Badgerys Creek (Lat. 34�S). Hybrid Bermudagrass ecotypes 6389 and 692 were established quickly at all sites while ecotypes 71 9 and 632 were satsifactory. Kikuyu was strong at all sites except Grafton but the rate of establishment of common couch was poor. At the frost-free sandy site of Mitchells Island, Bermudagrass ecotypes 719, 692, 6389, and 632 outyielded kikuyu by 75, 65, 65 and 35%, respectively. However, at Grafton and Coaldale, the highest yielding Bermudagrass ecotype, 719, had only 35% higher production than kikuyu. At the frost prone southern sites of Richmond and Badgerys Creek, the annual production of kikuyu was equal to that of ecotypes 719, 6389, 692 and 632. Common couch yields were equal to kikuyu at all sites except at Richmond. At Mitchells Island, the hybrid Bermudagrasses outyielded kikuyu in spring, summer and early autumn but in the late autumn kikuyu had equal and sometimes higher growth rates than the best Bermudagrasses. In winter, the growth of both species was negligible, although kikuyu, unlike the Bermudagrasses, did produce some new shoots at the base of the sward. Data on persistence under grazing were collected from only three of the sites but trends were similar to establishment. Ecotype 6389 had the highest persistence rating of the Bermudagrasses. Kikuyu failed at the poorly drained sandy site of Grafton but remained strong at the other sites. It was concluded that hybrid Bermudagrasses were of potential value for pastures in New South Wales, especially for sites with sandy soils and low frost incidence.

Summary-Nodulation problems with tropical legumes and lupins in northern New South Wales appeared due to the inoculant's failure to establish itself around the seedling root, and were more severe with direct drilling. The cause of this was investigated in a number of laboratory, glasshouse and field experiments. Krasnozem soils were found to be more inhibitory than three other types, but this did not appear related to pH or manganese content. Raising the pH of krasnozem soil with lime did not improve survival of rhizobia unless the soil was autoclaved. Soil extracts suppressed multiplication in sterile nutrient sand except when micro-filtered, but a greater increase occurred with no extract. Extracts of both carpet grass and kikuyu depressed nodulation of glycine (Neonotonia wightii) but only the carpet grass extract adversely affected Siratro (Macroptilium atropurpureum). Root washings of the two grasses restricted multiplication of Rhizobium lupini, kikuyu having the greater effect. Lupin seedlings growing in the presence of kikuyu roots had fewer rhizobia in the root zone and were less well nodulated except when inoculated at a high rate. The susceptibility of WU425 and the clover strain TA1 appears not to differ and the host plant (lupin or clover) did not influence rhizobium numbers in the rhizosphere. In the field both the number of rhizobia in the root zone of lupins and the percentage of plants nodulated, increased with increasing rate of inoculation. The results indicate that suppression is due to both miCro-organisms and a heat labile chemical factor. On the northern coast of New South Wales tropical legumes, during establishment, frequently suffer from a period of slow seedling growth with symptoms of nitrogen deficiency. This is most marked with direct drilling but can also occur in prepared seed beds, and is caused by poor nodulation (Cloonan and Vincent 1967). Evidence points to failure of the applied inoculum because most of the nodules that are present are produced by naturally occurring rhizobia (Date 1973). The problem appears to occur more frequently on krasnozem soils and on are* of carpet grass Oxonopus afinis) or kikuyu (Pennisetum clandestinum) rather than natural pastures or weedy areas. Forage lupins, particularly sweet yellow lupins (Lupinus luteus) have potential for overcoming the winter feed shortage on the northern coast (Royal and Hughes 1976). However, nodulation failure has occurred with sowings in new ground, but not where lupins have grown previously. Direct drilling into established pastures seems to result in poorer nodulation than sowing into prepared seedbeds. This paper reports both preliminary and detailed investigations to confirm some of these points.

Three experiments were conducted in which dairy cows multiple suckled beef x dairy cross calves during early lactation. After weaning calves grazed nitrogen fertilized kikuyu grass (Pennisetum clandestinum). In the first experiment each cow suckled two, three or four calves for 12 weeks. Pre-weaning calf growth rate increased significantly (P < 0.01) as the number of calves suckled was reduced, In the second experiment, calves suckled at three per cow for 6, 9 or 12 weeks gained at similar rates to weaning, reaching weaning liveweights of 52, 64 and 72 kg respectively. Neither the number of calves suckled in experiment 1 nor the length of the suckling period in experiment 2 significantly affected post-weaning growth rates. In the third experiment there was no significant difference between the growth rates of calves sired by Friesian and Angus bulls. After weaning, stocking rate treatments were imposed, there being a significant (P < 0.05) but small linear decline in growth rate as stocking rate was increased. The post-weaning growth rates of calves in all three experiments were poor when compared with growth rates reported for calves grazing temperate pastures.

The nutritive value of leaf material cut from a highly fertilized kikuyu grass (Pennisetum clan destinum) sward was assessed with penned sheep in a 6 x 6 latin square design over 21 8 days. Estimates of the nutritive value were made for the dried leaf, leaf with a mineral supplement, leaf milled and pelleted and for rations that contained the pellets and either oaten chaff or grain. The leaf had an organic matter digestibility (OMD) of 63.5 per cent and contained 3.5 per cent nitrogen (N). Milling and pelleting the leaf did not significantly affect those values although OMD was lower (60.5 per cent), voluntary intake higher (by 16 per cent) and the rate of da ily live mass gain by sheep (1 17 g day-1) increased threefold, compared with those on the unmilled leaf ration. All sheep had net retentions of N (range 2.7-10.1 g day-1 ; P < 0.01). The rate of wool growth did not differ significantly between sheep on the rations whereas the rate of live mass change was highest for sheep on pellets : grain (60 : 40) (183 g day-1) and lowest for sheep on pellets : chaff (60 : 40) (3 g day-1; P < 0.01).

The influence of cutting frequency (3, 6 and 9 weeks) and high nitrogen rates (0, 950 and 2860 kg N ha-1 yr-1) on the growth of an established kikuyu grass (Pennisetum clandestinum) sward were studied over three years, in an irrigated field experiment at Taree (lat. 32�s) on the mid-north coast of New South Wales. Forage yield was increased largely by nitrogen and to a lesser extent by increasing the harvest interval. Significant (P < 0.05) yield increases were obtained between 0 N and 950 N but not between 950 N and 2860 N. Yields ranged from 8900 kg DM ha-1 yr-1 (3 weeks, 0 N) to 25,200 kg DM ha-1 yr-1 (9 weeks, 2860). At 0 N, cutting every nine weeks increased yields over three and six weeks for most of the experimental period. There were no differences between three and six weeks at 0 N. With nitrogen there were significant yield differences between all cutting frequencies during periods of active growth. Longer cutting intervals increased the mean sward growth rates during most of the growing season but did not change the seasonal pattern of growth.Nitrogen yield increased with nitrogen rate and as cutting interval increased. Yields varied from 239 kg N ha-1 yr-1 (6 weeks, 0 N) to 932 kg N ha-1 yr-1 (9 weeks 2860 N). Nitrogen content was reduced as cutting interval increased.

The dry matter yield of 11 tropical legumes, 10 temperate legumes and 11 tropical grasses was examined in pot experiments on a clay soil with increasing levels of sodium chloride. A mathematical model was fitted to the yield-salt level curves for each species and both the half yield soil salinity level and zero yield soil salinity level were estimated. Species were ranked in relation to their salt tolerance at half and zero yield and these values were expressed in terms of the electrical conductivity of the soil saturation extract. Grasses showed a greater ability to persist at high salt levels than the legumes. The most tolerant grasses were Chloris gayana, Panicum coloratum, Pennisetum clandestinum, Sorghum almum and Digitaria decumbens. Medicago sativa, which was included in both temperate and tropical groups, was the most tolerant legume of both groups. The tropical legumes Macroptilium lathyroides and Macroptilium atropurpureum were almost equivalent to M. sativa in their salt tolerance. The least tolerant grass was Setaria anceps and the least tolerant tropical and temperate legumes were Desmodium uncinatum and Trifolium semipilosum respectively. Both Na and Cl percentages in the plant generally increased with increasing salt but no consistent relationship was found between plant salt tolerance and Na and Cl content. The field implications of the high salt tolerance of certain grasses is discussed in relation to the establishment of permanent grass-legume pastures on saline-sodic soils.

The short term response of tropical grasses during spring to ammonium nitrate and urea fertilizers (1 12 kg N ha -1) was measured on kikuyu (Pennisetum clandestinum) at one site, and on setaria (Setaria anceps cv. Kazungula) at two sites. Fertilizers were applied at weekly intervals on 16 occasions at each site during the August-December period. Treatments were assessed in terms of the dry matter response (DMR) and apparent recovery of fertilizer nitrogen (NR), where DMR is the differences in dry matter yield of topdressed plots over the control and NR is the corresponding difference in nitrogen yield expressed as a percentage of the amount of nitrogen applied as fertilizer. These responses were measured at four, and sometimes at eight weeks, and were related to environmental variables by regression analysis. The DMR was more responsive than NR to changes in temperature. Both DMR and NR were very sensitive to changes in soil moisture potential, especially on wet soils, and to changes in effective rainfall (rainfall less run-off). If low temperature limited growth during the first four weeks after topdressing, both DMR and NR increased further when growth during 5-8 weeks extended into warmer periods. However, when moisture supply limited the response at four weeks, the NR remained depressed at eight weeks even with an improved moisture supply. Environmental factors influenced the response more than the type of nitrogen fertilizer and at four weeks, the respective overall DMR and NR from urea were 90 and 86 per cent of those from ammonium nitrate.

The yields and seasonal growth curves of kikuyu grass, (Pennisetum clandestinum) setaria, (Setaria anceps cv. Kazungula) and broadleaf paspalum (Paspalum wettsteinii), were determined over a three year period at Taree (lat. 32�s) New South Wales with or without irrigation and under nil, 170 or 680 kg N ha-1 yr-1 (nil, low and high N). Annual forage yields averaged 1300, 51 00 and 13,000 kg DM ha-1 at nil, low and high N respectively. Kikuyu grass yields were significantly less than setaria or broadleaf, especially at low N. Both the apparent recovery of nitrogen and the efficiency of dry matter production by kikuyu grass were less than the other grasses. Yields from the irrigated plots were similar to the dryland plots due largely to a generally favourable rainfall pattern. During short dry periods the extra yield from irrigation was less than from the application of nitrogen. The patterns of seasonal growth were similar for each species at any one nitrogen rate and irrigation treatment. The growing season (>5 kg DM ha-1 day-1) without nitrogen, was only four to six months, commencing in late spring. This was increased to eight months at low N (October to May) and nine months (September to May) with high N. The mean period of high growth rates (>60 kg DM ha-1 day-1) over summer was nil at nil N, only six days at low N but increased to 154 days at high N. Winter growth was negligible.

In 3 experiments near Candelo, New South Wales, the effectiveness of tetrapion, glyphosate and 2,2-DPA in selectively removing Eragrostis curvula (agronomic type Tall Chloromelas) from a Pennisetum clandestinurn pasture was determined by applying each at various rates in each season of the year in 1981-82 (experiments 1 and 2) and in 1983 (experiment 3). Experiment 4 examined the effect of the herbicides on 3 cultivars of P. clandestinum when applied in each season in 1983-84. Tetrapion (2.25 and 3.00 kg/ha a.i.) was the most effective herbicide in killing E. curvula and promoting P. clandestinum in experiments 1 and 2, but, in experiment 3, glyphosate and 2,2-DPA were equally effective in killing E, curvula at 3 (glyphosate) and 2 (2,2-DPA) of the 4 application times. The differences between the results of the experiments were attributed to the herbicide being leached faster by the higher rainfall and being immobilised by the greater amounts of dead foliage of E. curvula in experiment 3. Despite occasional success in killing E. curvula, glyphosate and 2,2-DPA could not be considered for selective use as both were much more phytotoxic to P. clandestinum than tetrapion (experiment 4). Time of application had little influence on the selectivity of tetrapion, the least effective being May-June. In experiments 1 and 2, E. curvula was still well controlled by P. clandestinurn 5 years after the application of tetrapion. Pennisetum clandestinum cv. Crofts was more tolerant of tetrapion than were cvv. Whittet or Common.

Twelve legumes and eight grasses were grown from seed in controlled environment rooms at 14 hours daylength and daylnight temperatures of 32�/24�C. After 35 days the plants were cut and the following regimes were imposed-I : 14 hours, 32�/24�C ; 2 : 14 hours, 26�/15�C ; 3 : 11 hours, 26�/15�C; 4: 11 hours, 20�/6�C. Regimes 1 and 4 represent approximate summer and winter conditions in coastal Queensland, excluding frosts. A complete nutrient application, except nitrogen, was made to the legumes. Three regrowth harvests were obtained at 28 day intervals. There were few differences between primary growth and regrowth in N-concentration and estimated dry matter digestibility (DMD) of whole plant tops. The N-concentration and DMD of regrowth of all grasses increased as the conditions became less tropical. The legumes had a varied response, but there was little regime effect on N and DMD in Trifolium repens and T. semipilosum. Many of the tropical legumes made little or no regrowth in regime 4, but differences in N and DMD were small and inconsistent between other regimes. The legumes showed a general trend towards increased leafiness as conditions became less tropical, but in the grasses there was no consistent response, although nearly all had a higher percentage leaves in regime 4 than in 1. N concentration of the leaves of all legumes and of most grasses was higher than that of stems, but DMD of stems was higher than that of leaves in T. repens, T. semipilosum and Pennisetum clandestinum. N concentration of legume leaves was little affected by regime, but that of grasses was much higher in regime 4 than in the others. Stems of legumes showed a varied response in N and DMD, as did DMD of grass stems, but the latter generally tended to increase in N with decreasing temperature and daylength. N-concentration and DMD of the grasses had a negative linear correlation with DM yield, and most grasses a positive linear correlation between DMD and N-concentration. Of the legumes only M. sativa and Pueraria phaseoloides had a negative linear relation between DMD and DM yield and M. sativa a positive linear relation between DMD and N.

Nutrient deficiencies of old kikuyu (Pennisetum clandestinum Hochst.) and paspalum (Paspalum dilatatum Poir.) pastures on a krasnozem on basalt at Maleny, Queensland, were investigated. On the establishment of white clover (Trifolium repens L.), significant responses to phosphorus, potassium, molybdenum, and lime were recorded ; where clover did not establish well, as in the kikuyu sward, the overriding deficiency appeared to be nitrogen. Maximum response to phosphorus, as NaH2PO4, was achieved at a rate equivalent to 10 cwt superphosphate an acre. However, soil equilibrium potentialSP values and pot results with Ca(H2PO4), suggested a maximum near 20 cwt an acre might have been expected. An initial molybdenum application of 1 oz an acre was adequate : the main effect of lime was to release molybdenum in this acid soil (pH 4.6 in M/100 CaCl2). Aluminium and manganese were not toxic ; nevertheless, lime increased the yield and nitrogen content of clover grown in pots, possibly due to preferential nodule formation by the introduced rather than the 'native' rhizobia at the higher soil pH.

A nursery of single species and simple mixtures of 12 grasses and 9 legumes at Beerwah on the coastal lowlands of southern Queensland was grazed by sheep for over 16 years. For the last eight years 25.8 wethers a hectare (10.5/acre) were carried and thrived, heavy grazing pressure being maintained. Changes in botanical composition were recorded. The final mixture was dominated by Trifolium repens and Paspalm notatum. Other species to survive were Digitaria decumbens, Pennisetum clandestinum, Paspalum wettsteinii, and Brachiaria mutica. The majority of species failed to survive the close intense grazing by sheep. Annual replacements of phosphorus, sulphur, calcium, and potassium were made but nitrogen was never applied, and the highly productive pasture was maintained by legume nitrogen, mainly from white clover. Soil fertility improved under the pasture.

Pangola (Digitaria decumbens), kikuyu (Pennisetum clandestinum), setaria (Setaria sphacelata), and buffel grasses (Cenchrus ciliaris) were cut at different stages of growth and artificially dried to provide ten feeds with a range of leaf percentages (13-56), nitrogen contents (0.42-3.70 per cent), and acid detergent fibre percentage (26.3-43.3). Half of each cut was chaffed and the remainder pelleted. Both pellets and chaff were fed to Merino wethers in metabolism cages. Pelleting decreased the mean digestibility of dry matter by 6.8 percentage units, nitrogen by 2.2 percentage units, and ADF by 11.5 percentage units. Pelleting increased the mean voluntary intake by sheep 47 per cent for dry matter and 27 per cent for digestible dry matter with only minor differences in response to pelleting mature and young grass. The smallest increase from pelleting was 4.1 per cent for buffel grass containing 0.42 per cent N. In grass of the same age in which the nitrogen content had been increased to 0.75 by fertilizer nitrogen, pelleting increased intake by 26.6 per cent. It was concluded that with mature tropical grasses the response to pelleting may be limited by a low nitrogen content. Pelleting may be a useful technique for eliminating the effect of physical structure when studying factors affecting the voluntary intake of pasture plants.

The results of 45 sheep feeding experiments with kikuyu (Pennisetum clandestinum) based pastures are summarized. Mean values and the range of values for crude protein and normal acid fibre contents, dry matter, organic matter, and crude protein digestibilities and intake per kg liveweight0.75 are presented for the following pasture types : kikuyu, kikuyu plus nitrogenous fertilizer, Glycine wightii/kikuyu, Desmodium uncinatum/kikuyu and Vicia sativa/kikuyu. The relation between crude protein (CP) and crude protein digestibility, and CP and digestible crude protein for these five pasture types was established. Significant differences between pasture types are shown to exist and the importance of these differences discussed. A possible reason for differences in the relations found by previous workers is discussed.