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Methane emission was measured from 10 dairy cows and 12 wether sheep grazing kikuyu grass‐ (Pennisetum clandestinum) dominant pastures at Waimate North, Northland, in February 1997 and March 1999, and from 10 dairy cows grazing summer grass‐ (Digitaria sanguinalis) dominant pasture at Edgecumbe, Bay of Plenty, in March 2000. Methane emission was measured from each animal for 5 consecutive days in each measurement period using the sulphur hexafluoride (SF 6 ) tracer gas technique. Analysis of variance of the kikuyu grass chemical composition with sheep and cow data combined showed that the 1999 pastures were significantly higher in protein (P < 0.01), soluble sugars (P < 0.001), lipid (P < 0.01), and dry matter (DM) digestibility (P < 0.001) and lower in ash (P = 0.023), acid detergent fibre (ADF) (P < 0.001), and neutral detergent fibre (NDF) (P < 0.001) than the 1997 pastures, presumably as a consequence of urea topdressing in 1999. The chemical composition of the summer grass‐dominant pasture g...

Climate profiles were developed for 14 temperate C3 and subtropical C4 pasture species using the BIOCLIM procedure and survey data from 583 pasture sites throughout New Zealand. The species profiles differed in maximum and minimum thresholds for 27 solar radiation, temperature, and rainfall parameters. A cluster analysis detected three climate profile types. Cluster 1 species (Lolium perenne, Dactylis glomerata, Trifolium repens, Agrostis capillaris) differed from the others in the tolerance of drier, cooler, and lower solar radiation environments. Cluster 2 species (Rytidosperma racemosum, Sporobolus africanus, Paspalum dilatatum) showed greater tolerance of cooler and drier environments than species in Cluster 3 (Paspalum distichum, Setaria geniculata, Pennisetum clandestinum, Eleusine indica, Digitaria sanguinalis, Cynodon dactylon,Axonopus affinis). The results confirm broad differences in climate thresholds between C3 and C4 pasture species but the climate profile of the C3 species R. racemo...

Kikuyu pasture was grazed continuously for 12 months by 20 dry and 40 producing South African Mutton Merino (SAMM) and Merino ewes at a stocking density of 23 ewes ha−1. Supplementary sweet lupin seed was supplied to one group of producing ewes of each breed during pregnancy and lactation at a rate of 0.5% of the liveweights of the ewes. Rumen fluid samples for the determination of pH, volatile fatty acids (VFA), and ammonia‐nitrogen (NH3‐N) were collected from rumen‐fistulated wethers corresponding to the periods of late pregnancy and early lactation of ewes. Rumen NH3‐N concentrations (8.7 mg 100 ml−1 and 5.4 mg 100 ml−1) were low during both periods of sampling. Rumen VFA concentrations (12.3 mmol 100 ml−1 and 9.2 mmol 100 ml−1)were within normal ranges. Supplementation significantly increased blood urea concentration of ewes. Supplemented ewes lost less weight than the unsupplemented ewes (P ≤ 0.02) during the experimental period. Pregnancy (P ≤ 0.001) as well as lactation (P ≤ 0.0001) reduce...

Irrigated kikuyu pasture was continuously grazed for 12 months by 30 South African Mutton Merino (SAMM) and 30 Merino ewes at a stocking density of 23 ewes ha−1. Herbage samples for chemical composition were obtained monthly either by quadrat cuts or by oesophageally fistulated (OF) wethers. Intake was determined with controlled chromium release devices on eight dry and eight producing ewes from each breed during the periods of late pregnancy (February) and lactation (March). Significant (P ≤ 0.05) differences in the OM, OMD, CP, ADF, and NDF contents of manually collected and OF‐selected samples occurred between months. The means for CP, OMD, ADF, and NDF of the OF‐samples were, respectively, 18.3%, 62.3%, 37.8%, and 74.1% (expressed on an OM‐basis). During February, SAMM ewes (1184 ± 66 g d−1) consumed 27% (P = 0.01) more OM than Merino ewes (930 ± 66 g d−1), while there was no difference in intake between dry and pregnant ewes. During March, there were no differences in intake between breeds o...

Five C4 grasses [Pennisetum clandestinum (kikuyu); Cynodon dactylon cv. Coastcross 1; Digitaria eriantha spp. pentzii (pangola); D. pentzii (CQ911); Setaria sphacelata cv. Narok] were evaluated as components of three hill country pastures in Northland, New Zealand (lat. 34°S). Best site for all C4 grasses was a west-facing slope grazed by cattle and the most competitive species was kikuyu. After 4 years it occupied 2.5 times the area and had 5 times the herbage mass of the second most competitive species (‘Coastcross 1’). its rate of spread into resident pasture averaging 8, 11, and 21 cm/year. Under mowing, with two rates of nitrogen (N) fertiliser over summer (N0, N200 units), the control sward yielded 7.8 and 10.1 t herbage DM/ha per year on one site. Relative yields of swards with C4 grasses added were 2–138% for NO and 135–152% for N200, although stem/stolon material of C4 grasses accounted for 18–54% of total yield. Whole sward DM digestibilities were little affected by N rate, were higher ...

Small swards of 14 grasses of tropical origin (Cynodon dactylon, Digitaria spp., Paspalum dilatatum, Pennisetum clandestinum, Setaria spp.) and 6 of temperate origin (Dactylis glomerata ‘Grasslands Apanui’, Festuca arundinacea, Lolium perenne ‘Grasslands Nui’ and ‘Grasslands Ruanui’, Phalaris spp.) were established in the field at Palmerston North, After planting in late spring, herbage samples were taken during January through May of the following summer, dissected into lamina, sheath, and remainder (culms, stems, stolons), and analysed for total nitrogen, soluble sugar, starch, and in vitro digestibility. Proportion of lamina was 58–96% for the temperate grasses and 31–76% for the tropical grasses. Proportion of sheath was 5–20% for temperate and 22–36% for tropical grasses; and for the remainder fraction 0–22% and 2–44% respectively. Total nitrogen content of the lamina was higher than that of the sheath and remainder fractions. There was no clear distinction between temperate or tropical spec...

Application of gibberellic acid at 100 g a.i./ha in July resulted in rapid visual responses in both kikuyu grass and ryegrass swards in the form of elongation and a slight yellowing of foliage. Ground level cuts showed significant dry matter responses of both kikuyu grass and ryegrass to gibberellic acid, but they were smaller than the visual responses indicated. The greatest response from kikuyu was the equivalent of 11 kg DM/ha/day. In both grasses, gibberellic acid affected mainly the vertical distribution of dry matter, as reflected in either the dry matter yield or the proportion of dry matter above 3 cm. There were indications that gibberellic acid reduced regrowth after trimming of both kikuyu and ryegrass.

The warm-season yield of a range of C4-photosynthetic pathway summer-growing tropical grasses was measured by mechanical harvesting over three seasons in small-plot trials near Kaitaia under high levels of nutrition and pest control. Several of the grasses produced higher yields than the naturalised summer grasses Paspalum dilatatum and Pennisetum clandestinum. Irrigation sufficient to replace evaporative water loss substantially increased the early summer production of all grasses but usually decreased their early autumn production. Leaching of soil nutrients may have been partially responsible for the poor autumn production under irrigation. The grasses varied widely in their relative yield response to irrigation: Digitaria decumbens produced an extra 6855 kg dry matter/ha, but yields of Cenchrus ciliaris were not changed. Production of all grasses was lowest in late summer. Most of the summer grasses persisted reasonably well under the 5-week harvest interval and 5 or 10 cm cutting height, alt...

Pasture production was measured on plots infested with black beetle, Heteronychus arator (F.) (Scarabaeidae: Coleoptera), and insecticide-treated plots from 1983 to 1986 on sandy soils near Kaitaia in Northland. Black beetle densities ranged from 11 to 27/m2 on ryegrass (Lolium perenne L.)—dominant and from 16 to 112/m2 on kikuyu grass (Pennisetum clandestinum Hochst.) —dominant pastures. Livestock pulling plants from the soil caused pasture damage on plots infested with black beetle. Insecticidal control of black beetle, however, resulted in relatively small transient increases in pasture production. In contrast, nitrogen (N) applications significantly boosted production, ranging from 35 and 25 kg dry matter (DM)/kg N in spring to 25 and 17 kg DM/kg in winter for ryegrass- and kikuyu grass-dommant pastures, respectively. Spelling kikuyu grass p~sture from grazing over the summer and autumn III 1985 and 1986 resulted in an increase in pasture production of from 470 to 960 kg DM/ha. The role of bl...

Winter herbage covers were investigated as a means of protecting 5 tropical grasses from frost. Paspalum dilatatum, Pennisetum clandestinum, Cynodon dactylon, Digitaria scalarum and Setaria anceps were grown in small plots and overwintered under the following treatments: (1) tall stubble oftheir own herbage, (2) a short sward, (3) overdrilled lupin, and (4) overdrilled perennial ryegrass. During frosts grass stern-base mimimum temperatures under the heavy cover oftall stubble were 2°C warmer than under the short sward, but there were no significant differences in plant survival between the short sward and tall stubble. Stern-base temperatures were above O°C even during severe frosts in all treatments, but some plants died, especially in Setaria, even through meristems at soil level were not frozen. Chilling injury, as distinct from frost injury, may have killed them. Overdrilled lupin and ryegrass both failed to produce sufficient herbage by early winter from a 25 March sowing date to protect the...

Six tropical grass introductions were compared with Pennisetum clandestinum as pasture components under lax mowing in Northland for 3 years. All were in mixed swards with perennial ryegrass and white clover. A control treatment of ryegrass/clover alone was included. The mixed swards were relatively stable on a moisture-retentive soil at Kaitaia, but were unstable on a drought-prone soil at Sweetwater where ryegrass and clover did not persist. At a heavy frost site at Kaikohe, the tropical species were frost-damaged and either failed to persist or were minor sward components. Long-term evaluation of the tropical species in mixed swards was possible only at Kaitaia. Hemarthria altissima was planted only at this site where it persisted in mixed swards, whereas Aeroeeras maerum, Cynodon daetylon, Digitaria pentzii, D. sealarum, and Setaria sphacelata gradually disappeared as they were suppressed by ryegrass, clover, and volunteer species. Pennisetum clandestinum persisted as almost a pure stand by ex...

Kikuyu grass herbage (Pennisetum clandestinum) contained higher levels of cell-wall constituents than perennial ryegrass (Lolium perenne) grown under identical conditions. Much of this difference was due to hemicellulose rather than cellulose. A similar pattern was obtained with leaf blades from glasshouse-grown plants of the two species. Kikuyu grass stolons and leaf sheaths contained higher levels of structural carbohydrates than their corresponding leaf blades. In all of the kikuyu plant parts analysed the hemicellulosa level was 90-100% of the cellulose level. In leaf blades and sheaths of a second Pennisetum (P. typhoides) the level of hemicellulose was much lower than that of cellulose, which is typical of most festucoid and panicoid grasses.