Perennial Rye Research Articles

Grazing cows are more efficient than zero-grazed and grass silage-fed cows in milk rumenic acid production

Six rumen-cannulated Holstein cows in early lactation were assigned to 3 treatments: grazing (G), zero-grazing (ZG), and grass silage (GS) harvested from the same perennial rye grass sward in a 3×3 Latin square design with three 21-d periods. The objectives of this study were to investigate the underlying mechanisms for the reported elevation in milk rumenic acid (RA) concentration associated with G compared with ZG and GS, and to identify the important variables contributing to the milk RA response. Grazing animals were offered 20kg of dry matter/cow per day; indoor animals were offered ad libitum grass or silage. A concentrate at a rate of 3kg/d was also offered to all cows. Rumen, plasma, and milk samples were collected in the third week of each period. Data were analyzed by the MIXED procedure of SAS. Dry matter intakes were less for GS with no difference between G and ZG. Milk yield was greater for G than for ZG or GS. Milk fat and protein contents were less for GS with no difference between G and ZG. The combined intake (g/d) of linoleic and linolenic (18:3n-3) acids was different across the treatments (G: 433; ZG: 327; and GS: 164). Rumen pH was less for G with no difference between ZG and GS. Concentrations of volatile fatty acids and ammonia nitrogen in rumens were not different across the treatments. Wet rumen fill was less for G with no difference between ZG and GS. Vaccenic acid concentrations were different across the treatments in rumen (G: 12.30%, ZG: 9.31%, and GS: 4.21%); plasma (G: 2.18%, ZG: 1.47%, and GS: 0.66%) and milk (G: 4.73%, ZG: 3.49%, and GS: 0.99%). Milk RA concentrations were greater for G (2.07%) than for ZG (1.38%) and GS (0.54%). Milk desaturase index based on the ratio cis-9-14:1/14:0 was not different across the treatments. Milk RA yield per 100g of linoleic acid and linolenic acid intake (efficiency) was 2.23, 1.50, and 0.62g in G, ZG, and GS, respectively, suggesting that G cows were more efficient than ZG and GS cows in milk RA production. Stepwise regression analysis of a group of variables revealed that plasma vaccenic acid accounted for 95% of the variation in milk RA production. Milk desaturase index did not enter into the model. Overall findings suggest that substrate intake influenced milk RA production but it was not the only factor involved. There were differences in efficiency of milk RA production, which appears to depend on the factors regulating ruminal vaccenic acid production and its supply to the mammary tissue.

Phytoremediation and its effect on the mobility of metals in soil: a fractionation study

Studies were conducted to investigate the effect of phytoremediation on the immobilization of Cu, Pb, Mn and Zn in soils at different stages of plant growth. Two multi-metal soil concentrations were examined in pot experiments by growing five different plant species: Lolium perenne L. (perennial rye grass), Festuca rubra L. (creeping red fescue), Helianthus annuus L. (sunflower), Poa pratensis L. (Kentucky bluegrass) and Brassica napus L. (rape) for this study. Selective sequential extraction techniques differentiated the mobile and immobile metal fractions in the soil. Soil-metal conversions due to plant growth appear to follow the order: organic Cu to oxide Cu; oxide Pb to organic Pb; oxide Mn to exchangeable Mn; and exchangeable Zn to oxide Zn. As the growth of plants proceeded from 90 to 120 days after sowing, the relatively immobile fractions such as the oxide and organic fractions dominated in the soils growing Festuca, Lolium and Poa. The oxide fraction increased in soils growing Festuca, the organic fraction in soils growing Lolium and Poa, and the exchangeable fraction in soils growing Helianthus and Brassica. Based on the partitioning of metals in various soil fractions, Lolium, Poa and Festuca are identified as being suitable for the phytostabilization of metals (Cu, Pb, Mn and Zn) in moderately contaminated acid soil.

A field study on cost‐effectiveness of five erosion control measures

PurposeThe purpose of this study is to quantitatively evaluate five erosion control measures at a residential development area in Louisiana, USA in order to provide Best Management Practices (BMPs) that have been tested in the field with demonstrated cost‐effectiveness.Design/methodology/approachA total of six testing sites at a nine‐degree slope were used in parallel to study five erosion control measures with one being the control site (no protection). Soil erosion rate was quantified using the erosion bridge method. Soil underlying the study area was analyzed for surface runoff potential. Precipitation was monitored using a Sigma rain gauge. Analysis of variance (ANOVA) and Student Newman‐Keuls Post‐Hoc ANOVA analysis were conducted to evaluate statistical significance of erosion control effectiveness. Ratio of soil erosion rate reduction to cost of each control measure is also analyzed.FindingsAll erosion control measures studied were very effective in reducing soil erosion for soils with high runoff potential, ranging from 75 percent to about 100 percent reduction in soil erosion rate. The most effective soil erosion protection was observed by Geojute fabric and Curlex blanket with greater than 90 percent reduction in soil erosion rate. However, after factoring‐in cost, straw bedding was observed to be five times as cost‐effective as Geojute fabric and Curlex blanket. The most cost‐effective measure is temporary seeding using perennial rye grass. For each dollar spent, about 12 tons of soil per acre per year will be prevented from eroding.Originality/valueThe study evaluated erosion control measures in the field with quantitative cost‐effectiveness analyzed. Besides enforcement, providing practical and cost‐effectiveness control measures that have been tested in the field is critical for actual implementation of erosion control measures.

Alkaloids in Australian rye ergot (Claviceps purpurea) sclerotia: implications for food and stockfeed regulations

Rye ergot (Claviceps purpurea) occasionally causes toxicity (chiefly expressed as hyperthermia) in Australian livestock, either as a result of grazing infected annual (Lolium rigidum) and perennial (L. perenne) rye grasses, or if the ergot sclerotia produced in rye grasses contaminate grain crops used as stockfood. Alkaloids in 30 samples of Australian rye ergot sclerotia taken from rye grasses and grain screenings, and some feed samples contaminated with rye grass ergot sclerotia, were assayed by high performance liquid chromatography. Samples originated from across southern Australia. Ergotamine was the dominant alkaloid in all samples, followed by α-ergocryptine, ergocornine, ergosine and their respective -imine epimers. Ergotamine concentrations in sclerotia ranged up to 2257 mg/kg (as received basis). Ergocristine was a very minor component (<50 mg/kg) in all samples. Total alkaloids in freshly collected sclerotia ranged from 1003 to 3321 mg/kg (0.10 to 0.33%), and up to 3766 mg/kg with epimers included, although lower concentrations were found in samples stored for some time. Alkaloid profiles in sclerotia were all very similar, and concentrations did not appear to be related to size of sclerotia, source region, nor to the rye grass or grain from which they were taken. Previous cases of toxicity in livestock are reviewed and several new cases are reported. The implications of variable alkaloid contents of rye ergot sclerotia are discussed in terms of Australian food and stockfeed regulations.

Nitrogen conversion and nitrous oxide hot spots in energy crop cultivation

Since 1999, nitrous oxide (N<sub>2</sub>O) soil emissions from sites cultivated with energy plants have been measured by gas chromatography and gas flux chambers in experimental fields. The main aim of this study was the nitrogen conversion factor and its variability for sandy soils under climatic conditions of Central Europe. Annual plants (hemp, rape, rye, sorghum, triticale) and perennial plants (grass, perennial rye, poplar, willow) were fertilised with three different levels of nitrogen (150 kg N/ha/year, 75 kg N/ha/year, and none). The annual nitrogen conversion factors were derived from the annual mean differences between the fertilised sites and non-fertilised control sites. The mean nitrogen conversion factor for the non-cultivated soils was lower (perennial crops: 0.4%) than that for the regularly cultivated soils (annual crops: 0.9%). Few times, enhanced N<sub>2</sub>O emission spots with maxima above 1000 μ<sub>2</sub>O/m<sup>2</sup>/h, lasting for several weeks, were observed in the course of measurements. The influence of these local peak emissions on the nitrogen conversion factor is discussed.

Subacute ruminal acidosis (SARA) in grazing Irish dairy cows

Subacute ruminal acidosis (SARA) is a significant production disease of dairy cattle. Previous concerns have been raised over the occurrence of SARA in pasture-fed dairy cattle and the potential consequences of laminitis and lameness. Highly digestible perennial rye grass contains high concentrations of rapidly fermentable carbohydrate and low concentrations of physical effective fibre that may result in SARA. This study conducted a point prevalence survey of rumen health status in grazing Irish dairy cattle fed predominantly perennial rye grass-based pasture. The survey assessed rumen fluid, animal health status, milk production data and pasture composition. A total of 144 cows between 80 and 150 days in milk were sampled on 12 farms. Eleven percent of cows were classified as affected with SARA (pH⩽5.5), 42% were marginal (pH 5.6–5.8) and 47% were normal (pH>5.8). The study showed that low rumen pH is prevalent in grazing Irish dairy cattle consuming perennial rye grass-based pasture and raises concerns regarding effective pasture utilisation and possible consequences for animal health.

Assessing, mapping and quantifying the distribution of foliar biomass in Great Britain

This study has quantitatively mapped the distributions and peak above-ground foliar biomass of the 1000 most prevalent plant and tree species in Great Britain (GB) on a 1 x 1 km(2) grid. Each 1 x 1 km(2) grid cell was assigned to one of 56 land classes on the basis of environmental and land cover attributes. The mean occurrence and cover area of specific plant species within each land class was derived from the results of the Countryside Survey 1990 [Barr CJ, Bunce RGH, Clarke RT, Fuller RM, Furse MT, Gillespie MK, et al. Countryside Survey 1990 Main Report. HMSO, 1993]. Species-specific biomass conversion factors, relating above-ground living plant biomass (excluding tree timber) to a unit of ground area, were used to convert cover areas into species biomass. British totals of species cover area and biomass were then calculated. Lolium perenne (perennial rye grass), Triticum aestivurn (wheat) and Calluna vulgaris Ling (heather) covered the greatest areas of GB (26,811, 25,378 and 14,359 km(2), respectively). During summer (prior to harvest), L. perenne contributed 20% of the peak standing biomass in Britain (25.6 Mt), followed by T aestivum (18.8 Mt) and Hordeum vulgare (barley) (15.5 Mt). Picea sitchensis (Sitka spruce) was the dominant tree species in GB with the fourth highest peak foliar biomass (7.3 Mt). In total, 70 species accounted for 90% of the estimated summer biomass of GB. P. sitchensis and C. vulgaris dominated winter biomass. Predictive biomass distributions can be plotted for each species and examples of lowland and upland species are given. The predictions correspond well with known habitat preferences. Monthly variations in total biomass have also been plotted. (c) 2008 Elsevier Ltd. All rights reserved.

Effect of different grazing pressure by lambs grazing <i>Lolium perenne</i> and <i>Dactylis glomerata </i>pastures during spring on: 1. Diet quality

This study was undertaken to determine the influence of three grazing pressures [high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the quality of herbage consumed by lambs grazing Lolium perenne and Dactylis glomerata pastures in spring. Feed samples collected via oesophageal fistulae at the start and end of a six-week grazing period were analyzed for nitrogen (N), ash, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) concentrations, and in vitro digestibility of organic matter (IVDOM). In general, the quality of diets selected by lambs grazing both L. perenne and D. glomerata pastures was lower at the end than at the start of the grazing period. For both pastures the N concentration of herbage consumed by lambs in the HGP treatment was lower than for that in the LGP treatment. For L. perenne HGP resulted in the selection of a diet with higher fibre (NDF and ADF) concentrations and consequently lower IVDOM than in the LGP treatment. In the D. glomerata pasture, higher ADF and lower IVDOM were recorded in the MGP treatment compared to the other treatments. On the D. glomerata pasture the ADL concentration of the selected forage was lower in the HGP than in the MGP or LGP treatments. Forage selected on the L. perenne pasture had generally lower N, ash, ADF and ADL concentrations than those selected from the D. glomerata pasture. However, the IVDOM of the selected L. perenne was higher than that of selected D. glomerata. Keywords: Cocksfoot; chemical composition; diet selection; pasture availability; perennial rye grass South African Journal of Animal Science Vol. 36 (5) 2006: pp.46-49

Effect of different grazing pressures by lambs grazing <i>Lolium perenne</i> and <i>Dactylis glomerata</i> pastures during spring on: 2. Intake and growth

This study was undertaken to determine the influence of three grazing pressures [high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the performance of lambs grazing Lolium perenne and Dactylis glomerata pastures in spring. Feed intakes and average daily live weight gains (ADG in g/day) were determined for each group. In general intakes of both L. perenne and D. glomerata pastures were higher at the end of the study than at the onset. Grazing pressure had no effect on the intake of L. perenne, but on the D. glomerata pasture, HGP resulted in a decreased intake by the lambs compared to the LGP treatment. For both pasture species the ADG of the lambs were lower on the HGP compared to the MGP treatment, though intake and ADG of the lambs were higher when grazing L. perenne compared to D. glomerata. Keywords:Cocksfoot; diet selection; pasture availability; perennial rye grass; performance South African Journal of Animal Science Vol. 36 (5) 2006: pp.50-53

Asthma cases attributable to atopy: Results from the Third National Health and Nutrition Examination Survey

The percentage of asthma cases attributable to atopy is the subject of debate. The objectives were to estimate the percentage of asthma cases in the US population attributable to atopy and to examine associations between allergen-specific skin tests and asthma. Data were obtained from the Third National Health and Nutrition Examination Survey, in which subjects age 6 to 59 years were skin tested with 10 allergens. Atopy was defined as at least 1 positive allergen-specific test. Doctor-diagnosed current asthma was assessed by questionnaire. In the United States, 56.3% of the asthma cases were attributable to atopy, and that percentage was greater among males than females, among persons in the highest education category than in lower education categories, and among persons living in highly populated metropolitan areas than in all other areas. Each allergen-specific test was strongly associated with asthma before adjustment (odds ratios varied from 2.1 to 4.5); however, after adjustment by all the allergens, only tests to cat, Alternaria, white oak, and perennial rye were independently associated with asthma. Perennial rye was inversely associated with asthma. Of the 10 allergens, a positive response to cat accounted for the highest percentage of asthma cases (29.3%). About half of the current asthma cases in the US population represented by the Third National Health and Nutrition Examination Survey were attributable to atopy. Some allergen-specific skin tests were not independently associated with asthma. If atopy could be prevented or reversed, or its effect on asthma blocked, then a large percentage of asthma cases in the US population could be prevented.

Effect of age on methane emissions of red deer stags from weaning until one year of age grazing pasture

The aim of this study was to determine if methane emissions from young farmed deer increase with age. Methane emissions of 20 red deer stags grazing permanent perennial rye grass-based pasture were measured four times post-weaning, at 4.5, 6.5, 9 and 11.5 months of age, using the sulphur hexafluoride technique. Methane production and methane yield increased with age (P＜0.05) and appeared lower (26％) than previous measurements from adult deer on similar pasture. These results imply that total methane emissions from young deer recorded in the New Zealand Greenhouse Gas Inventory are likely to be overestimated if values are based on adult methane emissions only.

Seed set and some cytological characters in different generations of autotetraploid perennial rye (Secale montanum Guss)

Artificial autotetraploids of diploid perennial rye (Secale montanum Guss) plants were obtained by colchicine treatment. C1 C2 and C3 generations of autotetraploid perennial rye were compared for seed set and cytological characteristics such as irregularities in metaphase I (univalents) and anaphase I and II (lagging chromosomes and/or chromatids and bridge formation) and micronuclei in tetrads. In the three generations (C1 C2 and C3) the percentage of cells with univalents was 18.51, 14.56 and 9.38% respectively. The percentage of cells with irregular anaphase I with univalents was 23.43, 15.93 and 7.85%, and for anaphase II cells it was 20.93, 16.47 and 7.16. The percentage of tetrads with micronuclei was 18.17, 14.07 and 6.17% and seed set was 27.72, 43.51 and 59.59% respectively. A negative correlation was found between seed set and the cytological characteristics investigated. The correlations among the characters investigated during meiosis division were statistically significant. Selection of vigorous plants of autotetraploid perennial rye increased seed setting by increasing the cytological balance. However, abnormalities in the early stage of meiosis division were reflected in the later stages of meiosis.

Response to heat stress in warm season and cool season turf grass cultivars

In this study, we investigated differences between cool-season and warm season grasses when exposed to heat stress. The results show that Kentucky blue seed germination rate was the highest at 25oC (40-50%), decreased significantly at 30oC (23-30%) and dropped to 0 at 40oC. For the Bermuda cultivars, seed germination rate was two fold higher at 30oC then 25oC, and reached the highest at 40oC. The cool season perennial rye and Bent grass seeds germinated well between 25 and 30oC. Their germination rate was significantly lower at 40oC. After exposure to 38oC for 2 d, the chlorophyll content decreased significantly for Bermuda cultivars, remained stable for Bent grass and perennial rye, and increased to the greatest extentfor Kentucky blue. Leaf soluble protein contents increased significantly for Kentucky Blue, but remained stable for most of the other cultivars. Western blot with Hsp70 and dehydrin antibodies identified that the Bermuda cultivars had a dynamic changes in the profile of the heat and dehydration stress-related proteins. No similar changes were detected in Kenblue cultivars. High temperature induced dehydrin homolog proteins, but not the Hsp 70 in Perennial rye and Bent grass cultivars. Findings from this research can be used to differentiate cool season and warm season grass cultivars in terms of germination and survival ability under high temperature. Key words: seed germination, chlorophyll content, leaf soluble protein, heat shock protein, dehydrin protein.

The role of perennial rye (Secale cereale X S. montanum) in sustainable agriculture

The role of perennial rye (Secale cereale X S. montanum) in sustainable agriculture

Cover Crop Rotations Alter Soil Microbiology and Reduce Replant Disorders in Strawberry

In July 2001, a study was established in a field with a 30-year history of perennial strawberry production to examine effects on replant disorder of 12 different species of preplant cover crops, soil fumigation (methyl bromide plus chloropicrin), and fallow management. In May 2002, strawberries (`Jewel') were planted into pots containing soils with the incorporated cover crops, grown for 1 year, and then fruited. Strawberry yields in 2003 were highest in pots containing indiangrass (Sorghastrum avenaceum) and brown mustard (Brassica juncea) -incorporated soils, resulting in 32% and 28%, respectively, higher yield than plants in pots containing untreated, bare fallow soil. Yield was lowest in fumigated soil or soil incorporated with sunnhemp (Crotolaria juncea), having 19% and 10% less yield than the fallow treatment, respectively. In Aug. 1999, a complementary study was established in a field with a 7-year history of continuous perennial strawberry production to examine the effects of single species and multiple species rotations on replant disorder, bacterial populations, and fungal pathogens over 2 fruiting years. Cover crop treatments included various monocultures and sequences of perennial alfalfa (Medicago sativa), brown mustard, kale (B. oleracea `Winterbor'), sweet corn (Zea mays `Saccharata'), rye (Secale cereale), hairy vetch (Vicia villosa), marigold (Tagetes patula `Nema-gone'), oats (Avena sativa `Newdak'), and sudangrass (Sorghum bicolor × S. sudanese). These rotations were compared with the effects of fumigation using methyl bromide with chloropicrin (99:1), continuous strawberry, and bare fallow. Symptoms of replant disorder developed in the continuous strawberry plots within a few months of planting. Plants in the fumigation treatment produced greater fruit yield than all other treatments in 2003, 139% more than plants from the continuous strawberry treatment. Strawberry plants grown in the kale/sweet corn/rye treatment had consistently high yield, and both the hairy vetch/marigold/rye and the oats/sudangrass/rye treatments led to marked improvement over the continuous strawberry treatment. Plants from the brown mustard treatment also were more vigorous and productive than plants from the continuous strawberry treatment during 2002 despite having relatively low foliar biomass and a relatively high level of fungal infection on strawberry plant roots. In the field, symptoms of replant disorder were best overcome by fumigation with methyl bromide or multiple species rotations, particularly that of kale followed by sweet corn and rye. Although Rhizoctonia levels were associated with poor root health, general fungal and bacterial root infection rates were not consistently associated with the presence of visible symptoms of replant disorder nor with strawberry plant growth and productivity.

Culture-based and culture-independent assessment of the impact of mixed and single plant treatments on rhizosphere microbial communities in hydrocarbon contaminated flare-pit soil

Phytoremediation is a novel treatment option for weathered, hydrocarbon contaminated, flare-pit soil in prairie ecosystems. The remediation potential of six different naturalized prairie plants was assessed by examining their impact on the degradation potential of indigenous bacterial communities. Culture-based and culture-independent microbiological methods were used to determine if mixed plant treatments stimulate different microbial communities and catabolic genotypes in comparison to individual plant species that comprise the mix. DGGE analysis of PCR-amplified 16S rRNA genes revealed that alfalfa ( Medicago sativa) had a dominant effect on the structure of rhizosphere microbial communities in mixed plant treatments, stimulating relative increases in specific Bacteroidetes and Proteobacteria populations. Alfalfa and mixes containing alfalfa, while supporting 100 times more culturable PAH degraders than other treatments, exhibited only 10% TPH reduction, less than all planted treatments except perennial rye grass ( Lolium perenne). Total petroleum hydrocarbon (TPH) reduction was greatest in single-species grass treatments, with creeping red fescue ( Festuca rubra) reducing the TPH concentration by 50% after 4.5 months. Overall TPH reduction throughout the study was positively correlated ( p < 0.001 ) to culturable n-hexadecane degraders.

Relationships between microbial indices in roots and silt loam soils forming a gradient in soil organic matter

Perennial rye grass ( Lolium perenne) was grown in a greenhouse pot experiment on seven soils to answer the question whether the microbial colonisation of roots is related to existing differences in soil microbial indices. The soils were similar in texture, but differed considerably in soil organic matter, microbial biomass, and microbial community structure. Ergosterol and fungal glucosamine were significantly interrelated in the root material. This ergosterol was also significantly correlated with the average ergosterol content of bulk and rhizosphere soil. In addition, the sum of fungal C and bacterial C in the root material revealed a significant linear relationship with microbial biomass C in soil. The colonisation of roots with microorganisms increased apparently with an increase in soil microbial biomass. In the root material, microbial tissue consisted of 77% fungi and 23% bacteria. In soil, the fungal dominance was slightly, but significantly lower, with 70% fungi and 30% bacteria. Fungal glucosamine in the root material was significantly correlated with that in soil ( r = 0.65 ). This indicates a close relationship between the composition of dead microbial remains in soil and the living fraction in soil and root material for unknown reasons.

Plant toxicity testing to derive ecological soil screening levels for cobalt and nickel

Phytotoxicity tests were performed to set ecological soil screening levels for cobalt (Co) and nickel (Ni) following the American Society for Testing and Materials international E1963-98 Standard Guide for Conducting Terrestrial Plant Toxicity Tests. Two soils (a modified artificial soil mixed with 5% organic matter, pH 5.01, and a native riverine sandy soil with 0.1% organic matter, pH 6.3) were treated with cobalt(II) chloride or nickel chloride and allowed to age for four weeks before initiating tests. Alfalfa, barley, radish, perennial rye, and brassica were used to determine the appropriate range of concentrations and to select the most sensitive plant species for definitive tests. The tests were designed to have one to three test concentrations below the 20% effects concentration (EC20), and five to six test concentrations above the EC20. Definitive tests for each chemical used two soil matrices, three plant species, and replicates at 10 nominal concentrations, including negative control. Soil chemical concentrations were determined before planting and on completion of the phytotoxicity tests. Threshold responses interpreted as the EC20 for each species endpoint were calculated from regression analyses. The geometric mean of the EC20 values (excluding emergence, mortality, and nodule numbers) for each species resulted in values of 30.6 mg/kg for Co and 27.9 mg/kg for Ni.

Development of cropping technology and fodder value of perennial rye

Development of cropping technology and fodder value of perennial rye

Effect of environmental factors on the growth of grazed pasture in south-western Victoria

This paper presents work from several studies on pasture production that were conducted in south-west Victoria at the Pastoral Research Institute, Hamilton. The frequency with which pasture growth commenced for each week of autumn in the years from 1965 to 1991 was assessed. The median period for the commencement of growth was in the third week of March (although the average date was March 27). Autumn data from several trials conducted over 3 decades were collated and analysed. A relationship between the grazed pasture yield (average of stocking rates plots) at the end of autumn and the rainfall showed that 200 mm of rainfall in the 3 months to the end of May was optimal while higher rainfall depressed the growth. The average daily growth rates of introduced pasture (perennial rye grass, Lolium perenne L. cv. Victorian, phalaris, Phalaris aquatica L. cv. Australian, subterranean clover Trifolium subterranneum L. and volunteer species) were measured in 2- and 4-week growth periods (G 2 and G 4, kg DM/ha.day) for the seasonal growth cycles over 4 years (1980–84 except 1983) when grazed by Merino wether sheep at stocking rates of 10, 13 or 18 sheep/ha. The rainfall throughout the study was lower than normal. Although differences in the animal performance between the stocking rates were only small, at the low stocking rate capeweed (Arctotheca calendula L.) in patches became the major component of the sward. Greater variation in G 2 than in G 4 indicated that growth responded quickly to current environmental conditions. A nonlinear regression accounted for 74% of the variance in G 2 when related to the 3 climatic factors of daylength, soil temperature at 10 cm depth and the soil moisture to a depth of 10 cm, and a plant factor of green herbage yield. The 26 % of unaccounted variance appears to be associated with an effect of stocking rate, possibly botanical composition. The botanical composition was not continuously monitored hence the only sward character included in the investigation was herbage yield. Comparison of the patterns of pasture growth from different latitudes indicated that while the growth pattern in south-western Victoria is erratic, it is intermediary between Mediterranean and temperate pasture types. Understanding this aspect has implications for improving the efficiency of animal production in this environment.