White Clover Swards Research Articles

Mixtures of clovers with plantain and chicory improve lamb production performance compared to a ryegrass–white clover sward in the late spring and early summer period

AbstractA research programme was undertaken over two consecutive years with the purpose of studying the effect of herb–clover swards on lamb production performance year‐round. The focus of this study was on two consecutive late spring and early summer periods (2011, 2012). In each year, three sward treatments were compared on grazed paddocks with 40 lambs ha−1: (i) grass–clover mixture (perennial ryegrass [Lolium perenne L.] and white clover [Trifolium repens]); (ii) plantain–clover mixture (plantain [Plantago lanceolata], white clover and red clover [Trifolium pratense]); and (iii) chicory–plantain–clover mixture (plantain, chicory [Cichorium intybus L.] and white and red clovers). Lambs were weighed at 2‐week intervals, and carcass weights and GR tissue depth measurements were obtained at slaughter. In both years, lambs on treatments (ii) and (iii) had greater (P < 0·05) final live weight, liveweight gain, carcass weight, dressing‐out percentage and GR tissue depth measurements, and lower feed conversion ratio compared to lambs on treatment (i). Lamb production was similar in treatments (ii) and (iii) (P > 0·05) in each year. Therefore, during the late spring and early summer period, herb–clover mixture swards were found to be a superior option to perennial ryegrass–white clover for finishing lambs.

Grazing alternative herbages in lactation increases the liveweight of both ewe lambs and their progeny at weaning

Breeding ewe lambs is a management tool that can be used to increase farm profit. However, there are potential negative impacts on the liveweight of progeny at weaning and the liveweight of the ewe lamb at the following breeding. A potential method of minimising these impacts is through the provision of quality herbages such as lucerne or a herb mix containing chicory, plantain, and red and white clover. The aim of this 2-year study was to examine the impact of offering ewe lambs either a traditional ryegrass and white clover pasture (Pasture), Herb-mix or Lucerne throughout the lambing period and in lactation. During lactation in both years of the study, ewe lambs offered the Herb-mix or Lucerne treatments were heavier (P < 0.05) than those offered Pasture. In addition, progeny of ewe lambs offered the Herb-mix or Lucerne treatment were also heavier (P < 0.05) in lactation than those born onto ryegrass white clover. Interestingly, in one of the 2 years, the ewes and their progeny on the Lucerne treatment were heavier (P < 0.05) in lactation than those in the Herb-mix treatment. Combined, these results indicated that offering either Herb-mix or Lucerne increases the performance of the young dam and her progeny above that found on a ryegrass and white clover sward.

Impact of spatial heterogeneity of plant species on herbage productivity, herbage quality and ewe and lamb performance of continuously stocked, perennial ryegrass–white clover swards

AbstractThe benefits of white clover (Trifolium repens L.) in pastures are widely recognized. However, white clover is perceived as being unreliable due to its typically low content and spatial and temporal variability in mixed (grass‐legume) pastures. One solution to increase the clover proportion and quality of herbage available to grazing animals may be to spatially separate clover from grass within the same field. In a field experiment, perennial ryegrass (Lolium perenne L.) and white clover were sown as a mixture and compared with alternating strips of ryegrass and clover (at 1·5 and 3 m widths), or in adjacent monocultures (strips of 18 m width within a 36‐m‐wide field). Pastures were stocked by ewes and lambs for three 10‐month grazing periods. Over the 3 years of the experiment, spatial separation of grass and clover, compared with a grass–clover mixture, increased clover herbage production, although its proportion in the sward declined through time (0·49–0·54 vs 0·34 in the mixture in the first year, 0·28–0·33 vs 0·15 in the second year and 0·03–0·18 vs 0·01 in the third year). Total herbage production in the growing season in the spatially separated treatments decreased from 11384 kg DM ha−1 in the first year to 8150 kg DM ha−1 in the third year. Crude protein concentration of clover and grass components in the 18‐m adjacent monoculture treatment was greater than the mixture treatment for both clover (310 vs 280 g kg−1 DM) and grass (200 vs 180 g kg−1 DM). There was no clear benefit in liveweight gain beyond the first year in response to spatially separating grass and clover into monocultures within the same field.

Complementary effects of red clover inclusion in ryegrass–white clover swards for grazing and cutting

AbstractIncreasing plant species diversity in grasslands may improve productivity and stability of yields. In a field experiment, we investigated the herbage dry‐matter (DM) yield and crude protein content of two‐species swards of perennial ryegrass–white clover (Lolium perenne L.–Trifolium repens L.) and three‐species swards of ryegrass–white clover with red clover (Trifolium pratense L.). Five different managements represented cutting, grazing and combinations thereof, with different slurry fertilization treatments in 1‐ to 4‐year‐old swards. The three‐species mixture out‐yielded the two‐species mixture in years 1 and 2. Across all 4 years, yields were 8–10% higher in cut swards. Inclusion of red clover increased the yields of clover across the 4 years by 51% without fertilizer and by 90% when fertilized. Responses to slurry fertilization were similar in both mixtures and were mainly independent of sward age. There was a complementary effect over the season and across managements. Red clover dominated in the first and third cuts; white clover dominated in the second and fourth cuts. Red clover dominated in cut swards and white clover in grazed swards. Future prospects of the inclusion of red clover in sown swards are discussed. These may include higher nitrogen‐use efficiency in ruminants, increased soil fertility and improved sward flexibility to cope with changing managements. The findings also suggest positive yield effects of alternating between cutting and grazing within the season or between years.

Productivity and botanical composition of orchardgrass–white clover swards in a cool‐temperate hill land region of the eastern United States

AbstractUnderstanding the growth dynamics of grass–legume swards is critical as pastoral management practices are adapted to varying economic constraints and emerging environmental considerations. Efficient management must synchronize the use of accumulated herbage with the needs of grazing livestock. This must be accomplished against the dynamic background of within and among year weather patterns interacting with herbage growth and grazing animal behavior. In the Appalachian region of the eastern United States, pastures often are dominated by orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.). We determined botanical composition and herbage productivity of orchardgrass and white clover swards during four consecutive years when managed as a function of canopy development and regrowth interval. Productivity was influenced by defoliation practices when mixtures were managed according to canopy development. Productivity was greatest when swards were managed as hay or when clipped to a 5‐cm residue each time mean canopy height reached 20 cm. White clover declined and orchardgrass increased in the sward irrespective of defoliation treatment. Botanical composition of mixtures with the erect growing orchardgrass tended to be more stable, whereas swards including the decumbent orchardgrass tended to be invaded by weeds. Some increase in productivity occurred during the first growing season when mixtures were clipped at either 2‐ or 4‐week intervals. Regardless of defoliation practice, white clover, and in some instances orchardgrass, presence declined during two consecutive growing seasons with various other volunteer grasses and forbs contributing to productivity. Productivity and persistence of sown sward components may be less dependent on management practices than on the expression of interactions responding to within and among year weather patterns.

Simulating the grazing of a white clover 3-D virtual sward canopy and the balance between bite mass and light capture by the residual sward.

The productivity and stability of grazed grassland rely on dynamic interactions between the sward and the animal. The descriptions of the sward canopies by standard 2-D representations in studies of animal-sward interactions at the bite scale need to be improved to account for the effect of local canopy heterogeneity on bite size and regrowth ability. The aim of this study was to assess a methodology of 3-D digitized canopies in order to understand the balance between bite mass and light interception by the residual sward. 3-D canopy structures of four white clover swards were recorded using a POLHEMUS electromagnetic digitizer and adapted software (POL95). Plant components were removed after digitizing to determine aerial dry matter. Virtual canopies were synthesized and then used to derive canopy geometrical parameters, to compute directional interception and to calculate bite mass. The bit masses of cattle and sheep were simulated according to their form, depth and placement on the patch, taking account of explicit sward architecture. The resulting light interception efficiency (LIE) of each organ was then calculated using a projective method applied to the virtual residual sward. This process enabled an evaluation of light interception based on Beer's law at the bite scale. The patterns of the vertical profiles of LAI appeared as bimodal, triangular or skewed parabolic functions. For a single bite of similar area and depth, the lowest mass was observed with half-spherical form and the highest for the cylindrical form, whatever the initial sward structure. The differences between the actual LIE and that calculated by Beer's law were marked for residual swards shorter than 8 cm. Bite mass and LIE values after grazing were more strongly affected by the initial structure of the sward than by bite form and placement. 3-D digitizing techniques enabled a definition of the geometry of each component in sward canopies and an accurate description of their vertical and horizontal heterogeneities. The discrepancy between Beer's law results and actual light interception was reduced when the sward regrew rapidly and if the rest period was long. Studies on the biting process would greatly benefit from this method as a framework to formulate and test hypotheses in a quantitative manner.

Optimizing legume content and forage yield of mown white clover–Italian ryegrass mixtures through nitrogen fertilization and grass row spacing

AbstractMixed swards of white clover–grass mixtures in highly productive environments often fail to reach the minimum recommended annual clover proportion of about 0·30. This study assessed the effect on clover content and total dry matter (DM) yield of two spring N applications (0 and 45 kg N ha−1) and two distances between drilled grass‐rows (0·18 and 0·36 m) over 3 years for mown swards of white clover–Italian ryegrass (Trifolium repens–Lolium multiflorum) in binary mixtures in northern Italy. An additional aim was to determine the advantage of association of grass–clover compared with grass and clover monocultures. On average, N fertilization of mixtures resulted in almost 9% higher total yield (P < 0·01; mean response = 18·1 kg of total DM per kg of N) but decreased the clover proportion (0·250 vs. 0·312). Wider grass‐row spacing increased clover proportion (0·327 vs. 0·234; P < 0·01) with no reduction of total DM yield. N fertilization × grass‐row spacing interaction occurred only for clover content (P < 0·01). Without N fertilization, mixtures out‐yielded clover and grass pure stands. With N fertilization, at double rate to pure grass, yields from mixtures were greater than from clover and comparable to Italian ryegrass.

N 2O emissions from boreal grass and grass - clover pasture soils

We studied the annual N 2O emissions from boreal dairy pastures in Eastern Finland. The N 2O emissions were measured with a chamber technique from a timothy–meadow fescue sward with mineral N fertilization and from a grass–white clover sward without fertilization. The simulated dung and urine patches were applied either in June or August during two grazing seasons. The measurements were carried out 1 year after applications after the first season and continued for another year after the second season to measure possible after-effects. The annual N 2O-N emissions from the grass sward varied between 3.2 and 4.1 kg ha −1 and from the grass–clover sward between 6.4 and 7.6 kg ha −1. The N 2O-N emission from the grass pastures expressed as a proportion of the applied N was 0.6–1.4% for the control plots (without excreta), 0.4–0.9% for the urine and 0.7–4.5% for the dung-treated areas. After 1 year the N 2O emissions from the urine or dung plots did not differ from those from the untreated control plots. The time of application of the excreta had a minor effect on the emissions. The accumulation of N 2O in the soil was measured from the control and treatment plots during winter and the release of accumulated N 2O during the thaw contributed to the high emissions in spring. Winter-time N 2O emissions were 25–78% of the annual total indicating the importance of the cold period in the annual N 2O emissions in boreal regions. In conclusion, the magnitude of the annual N 2O emissions was rather similar to that from temperate pastures despite the large differences in climatic factors and the dynamics of N 2O emissions.

Can a herb and white clover mix improve the performance of multiple-bearing ewes and their lambs to weaning?

The productive performance of highly fecund ewes and their progeny on ryegrass-based swards is limited in late pregnancy and lactation. Alternative herbages, such as chicory, plantain and red and white clover, have the potential to improve performance levels. In the present study, 49 twin- and 42 triplet-bearing Romney composite ewes bred to either Suffolk or Romney rams were allocated to one of three nutritional treatments from Day 131 of pregnancy [19 twin ewes on a ryegrass–white clover sward mix (Rye/WC); 16 twin ewes on a plantain–ryegrass sward mix (Plant/Rye); 14 twin ewes on a chicory–plantain–red and white clover sward mix (Herb); 13 triplet ewes on Rye/WC; 16 triplet ewes on Plant/Rye; and 13 triplet ewes on Herb] and remained on these sward treatments with their lambs until 75 days after the midpoint of the lambing period (L75). Nutritional treatment had no effect (P > 0.05) on ewe liveweight, body condition score (BCS) or non-esterified fatty acid and β-hydroxybutyrate concentrations on Day 145 of pregnancy. At L75, ewes on the Herb treatment sward were heavier than ewes on Plant/Rye (70.75 ± 1.31 v. 61.43 ± 1.28 kg, respectively) and had a higher BCS than ewes on either Plant/Rye or Rye/WC (2.7 ± 0.1, 2.2 ± 0.1 and 2.3 ± 0.1, respectively). Sire type and nutritional treatment had no affect (P > 0.05) on lamb birthweight or weight at L75. At L20, lambs born to ewes on the Herb sward treatment were heavier than those on the Rye/WC and Plant/Rye treatments (8.74 ± 0.23 v. 7.98 ± 0.23 and 7.79 ± 0.22 kg, respectively; P < 0.05). Neither birth rank, sire type nor ewe treatment had any effect (P > 0.05) on maximum heat production on a per kg liveweight basis or total heat production. Romney-sired lambs on the Herb sward treatment had higher (P < 0.05) survival rates than those on the Rye/WC sward treatment (97.8% v. 61.7%, respectively). However, no such relationship was observed in lambs born to Suffolk sires (79.8% v. 84.8%, respectively). The survival response resulted in greater (P < 0.05) total liveweight of Romney-sired lambs at L75 per ewe on the Herb nutritional treatment than on the Rye/WC treatment (61.6 ± 5.0 v. 36.7 ± 4.6 kg, respectively) a relationship not observed (P > 0.05) in Suffolk-sired lambs. In conclusion, the present study indicates that there is the potential to improve the productive performance of multiple-bearing ewes and their lambs by grazing on a Herb sward mix.

Fermentation patterns and nutrient contents of forb-containing silages and their effects on microbial fermentation in the artificial rumen system RUSITEC

SUMMARYGrassland forbs are important constituents of swards under low-input management. The hypothesis tested was that herbage from unfertilized swards consisting of a mixture of perennial ryegrass (Lolium perenne), white clover (Trifolium repens), dandelion (Taraxacum officinale) and ribwort (Plantago lanceolata) (treatment GCF) would exert a significant effect on the composition and quality of silage for rumen microbes compared with herbage from nitrogen-fertilized (50 kg N/ha/cut) pure ryegrass swards (treatment GN) or unfertilized ryegrass white clover swards (treatment GC). GCF had average proportions of clover and forb of 0·21 and 0·58, respectively. The crude protein and fibre fractions declined and non-fibrous carbohydrates (NFC) increased from GN over GC to GCF. Irrespective of cutting date (spring and summer), GN showed extremely high ammonia (NH3) concentrations, whereas GCF resulted in the highest concentrations of lactic acid coinciding with the lowest contents of butyric acid and ethanol. The ratios between the soluble and less soluble N fractions decreased in the order GN>GC>GCF. A similar sequence was observed in RUSITEC for the apparent disappearance rates of crude protein and fibre fractions. The concentration of NH3-N in the fermenter fluid declined in the order GN>GC>GCF. GCF produced less short-chain fatty acids (SCFA) than GN and GC. Microbial nitrogen (MN) flow was not significantly different between treatments but tended to decline in the order GN>GC>GCF, whereas the proportion of MN originating from NH3-N increased inversely. The efficiency of microbial protein synthesis was unaffected by the different silages. It is concluded that forb-rich swards are suitable for the preparation of high quality silages. There is a need for further investigation into postruminal availability and suitable supplementation for such silages in order to fully exploit their potential for improving the efficiency of nitrogen utilization in ruminant nutrition.

Sustainable Turkey Litter Amendments for Mixed Swards Grazed by Sheep in Appalachia: Nitrate Leaching

ABSTRACT Increased poultry production in the Appalachian Region provides a readily available nutrient source and a means to improve soil quality. As with any applied source of nutrients, surface and ground water quality can be compromised if nutrient inputs exceed plant nutrient requirements. Understanding nutrient dynamics in hill-land pasture enables us to develop management practices that minimize detrimental effects on water quality, and stabilize and improve the productive capacity of highly eroded soil. The objective of this research was to assess nitrate leaching under mixed swards of orchardgrass (Dactylis glomerata), white clover (Trifolium repens), and chicory (Cichorum intybus) receiving various loadings of composted turkey litter and grazed by sheep (Ovis aries). Treatments were applied in the early spring of 1997, 1999, and 2001 and consisted of P and K only; N, P and K; 3 Mg ha−1 composted turkey litter; and 6 Mg ha−1 composted turkey litter. Indications were that any of the treatments supplied adequate herbage to sustain rotational stocking of growing lambs at 50 lambs per hectare, but NO3-N leaching occurred at the litter application rate of 6 Mg ha−1. Nitrate leaching also occurred when no additional N was applied as a result of an increased ratio of white clover in the sward. When chicory is included in the sward composition, rates of composted turkey litter application greater than 3 Mg ha−1 cannot be recommended from a NO3-N leaching perspective.

Productivity, persistence and nematode impact in pure and mixed swards of white clover and Lotus corniculatus

The effect on pasture productivity of sowing birdsfoot trefoil (Lotus corniculatus) and white clover (Trifolium repens) as pure and mixed swards was evaluated over two growing seasons. Different sowing techniques were used for mixed sward treatments: species sown in alternate rows, mixed within rows or broadcast. Keywords: birdsfoot trefoil, Lotus corniculatus, pasture production, plant nematodes, white clover

Effects of cutting frequency on plant production, N‐uptake and N2 fixation in above‐ and below‐ground plant biomass of perennial ryegrass–white clover swards

AbstractNitrogen (N), accumulating in stubble, stolons and roots, is an important component in N balances in perennial ryegrass–white clover swards, and the effects of cutting frequency on the biomass of above‐ and below‐harvest height were studied during two consecutive years. Total dry matter (DM) and total N production, and N2 fixation, were measured at two cutting frequencies imposed in the summers of two years either by cutting infrequently at monthly intervals to simulate mowing or by frequent cutting at weekly intervals to simulate grazing. Total DM production harvested was in the range of 3000–7000 kg DM ha−1 with lower DM production associated with the frequent cutting treatment, and it was significantly affected by the different weather conditions in the two years. The higher cutting frequency also reduced the biomass below harvest height but the different weather conditions between years had less effect on stubble and, in particular, biomass of roots. The biomass of roots of white clover was significantly lower than that of roots of perennial ryegrass and remained at a relatively constant level (200–500 kg DM ha−1) throughout the experiment, whereas the biomass of perennial ryegrass roots increased from 2400 kg DM ha−1 in the year of establishment to 10 200 kg DM ha−1 in the infrequent cutting treatment and 6650 kg DM ha−1 in the frequent cutting treatment by the end of the experiment, giving shoot:root ratios of 4·7–16·6 and 0·5–1·6 for white clover and perennial ryegrass respectively. Annual N2 fixation was in the range of 28–214 kg N ha−1, and the proportion of N fixed in stolons and roots was on average 0·28. However, as weather conditions affect the harvested DM production and the shoot:root ratio, care must be taken when estimating total N2 fixation based on an assumed or fixed shoot:root ratio.

The productivity of irrigated legumes in northern Victoria. 2. Effect of grazing management

The productivity of irrigated white (Trifolium repens L.) and red (Trifolium pratense L.) clover swards was compared in an experiment of more than 3 years duration. It was hypothesised that white clover would be more productive than red clover when defoliation was frequent and intense, and less productive when defoliation was infrequent and lax. The experiment was a factorial design involving 2 species of clover [white clover (cv. Haifa) and red clover (cv. Redquin)], 2 grazing frequencies and 2 grazing intensities (with the criteria for both being based on quantities of herbage present before/after grazing). There were 4 extra treatments sown: perennial ryegrass (Lolium perenne L. cv. Grasslands Nui) and white clover (cv. Haifa), lucerne (Medicago sativa L. cv. Validor), Persian clover (Trifolium resupinatum L. cv. Maral) or subterranean clover (Trifolium subterraneum L. cv. Trikkala), but only 1 defoliation treatment was used for each of these treatemnts. There were 4 replicated blocks of all treatments. Apparent growth rates [calculated from measurements of dry matter (DM) removed by grazing] of white clover ranged from a low of 10 kg DM/ha.day in winter to a high of 70 kg DM/ha.day in summer. The growth rates of white clover swards were superior to those of ryegrass and white clover swards over summer, but were generally lower from May to October. In 2 of the 4 years, frequent grazing of white clover resulted in greater (P<0.05) production than infrequent grazing (average of 12.8 v. 10.7 t DM/ha) whereas intensity of grazing only affected DM net accumulation in the first year (P<0.05). The data show no evidence of a decline in productivity over time. Sward structure of white clover was influenced by grazing treatment with the numerically highest yielding treatment (frequent and hard) having the highest density of stolon tips (vegetative buds). In relation to days of regrowth, the frequently grazed treatment had higher levels of net photosynthesis in spring and summer compared with the infrequently grazed treatment. The frequently grazed treatment achieved positive carbon balance immediately after grazing and reached maximum levels of photosynthesis at 8–10 days, whereas the infrequent treatment showed negative carbon balance for the first 2–3 days after grazing with maximum photosynthesis being achieved later than in the frequently grazed treatment. When net photosynthesis was related to leaf area, there were fewer differences between the 2 treatments. The exception was in spring when photosynthesis was lowest where the initial leaf area was highest in the infrequent and hard treatment. Maximum photosynthesis was achieved at diminishing leaf area index from spring through to winter. Red clover was the most productive legume in the first year after establishment, but it did not persist beyond the second year and its DM net accumulation was reduced by more frequent grazing (12.4 v. 15.3 t DM/ha in the first year and 6.1 v. 9.1 t DM/ha in the second year; P<0.05). The DM net accumulation of lucerne was greater than that in any other treatment (an average of 16.7 t DM/ha in the 2 completed years), whereas the annual legumes, subterranean clover and Persian clover, averaged 6.6 and 10.7 t DM/ha.year, respectively. The seasonal growth rate data showed that lucerne had very good summer production whereas the annuals tended to be at least as good as the perennials from May to October.

The productivity of irrigated legumes in northern Victoria. 1. Effect of irrigation interval

An experiment was undertaken to determine the production and water use of pure swards of white clover (Trifolium repens L. cv. Haifa), red clover (Trifolium pratense L. cv. Redquin) and lucerne (Medicago sativa L. cv. Validor) between December 1987 and December 1990. The experiment was a split plot design with 3 irrigation interval treatments, which were the main plots, and 3 legume species, which were the subplots, all of which were replicated 4 times. Irrigation frequency was determined by evaporation minus rainfall (E-R) and was scheduled to occur at intervals of about 40, 80 or 120 mm of cumulative E-R. Annual amounts of harvested dry matter (DM) ranged from 8 to 22 t/ha depending on irrigation and species treatment. There was an interaction (P<0.05) between irrigation interval and species during each irrigation season. White clover DM harvested was reduced (P<0.05) by an average of 23 and 41%, respectively, as irrigation intervals were extended beyond 40 mm E-R (where up to 12 t DM/ha was recorded in an irrigation season). The decline in white clover growth in the less frequently irrigated treatments, relative to the 40 mm E-R irrigation treatment, was most pronounced between December and February, the months of highest evaporative demand, when these swards were 30 and 52% less productive (80 and 120 mm E-R, respectively). This compared with reductions of 16 and 32%, respectively, for red clover and 1 and 4%, respectively, for lucerne during the same period. Red clover, a dense productive stand initially, lost vigour and density in the second summer of this experiment, and from February in the second year was not harvested. However, for the period during which it was harvested, red clover production was reduced (P<0.05) by 21%, on average, when the irrigation interval was 120 mm E-R compared with the 40 and 80 mm E-R irrigation treatments. The production of lucerne was not affected (P>0.05) by the range of irrigation frequencies used in this experiment, although its crown density in the most frequent irrigation treatment was 30% less than in the 2 less frequently irrigated treatments when measurements were terminated in December 1990. However, after the first year, the lucerne swards were all highly productive, producing up to 21 t DM/ha in an irrigation season. For white clover to be productive, frequent irrigation is essential. However, all the indices of plant and sward performance measured during intensive studies showed that frequent irrigation of white clover resulted in earlier onset of water stress relative to the less frequent irrigation intervals. Despite this earlier onset of water stress, the yield advantage of frequent irrigation was large. Red clover and lucerne were less reliant on frequent irrigations to maintain productivity than white clover. However, red clover may need to be re-sown on a regular basis in the northern Victorian environment because of its failure to persist beyond 2 years. It is suggested that lucerne should be considered in preference to white clover because of its greater water use efficiency and its less critical reliance on irrigation management to maintain productivity.

Effects of initial sowing rate and subsequent grazing management on the growth and clover content of irrigated white clover - perennial ryegrass swards in northern Victoria

Two experiments were conducted over 3 years. One was of factorial design involving 2 sowing rates of white clover (Trifolium repens L. cv. Haifa; sown at 8 or 3 kg/ha) and perennial ryegrass (Lolium perenne L. cv. Grasslands Nui; sown at 5 or 15 kg/ha) grazed by dairy cows at 2 frequencies [frequent (2–3 weeks in spring/autumn) and infrequent (4–6 weeks in spring/autumn)] and 2 intensities [hard (residual rising plate meter heights of less than 4 cm) and lax (residual rising plate meter heights of more than 5 cm)]; and the second was a regression design involving 5 sowing rates of white clover and ryegrass ranging from pure clover to pure ryegrass (sown at 10/0 through to 0/20 kg/ha), all grazed frequently and at a hard intensity. The hypotheses tested were that (1) pure white clover swards would be at least as productive as those that contained ryegrass, and (2) more frequent grazing would result in greater quantities of DM removed, while hard grazing would maintain a higher clover content. In general, the hypotheses were confirmed. Over the 3 years of the experiments, pure white clover swards were at least as productive as mixed swards in a situation where no nitrogen fertiliser was applied. In the first year, the amount of DM removed declined (P<0.05) as the ryegrass sowing rate increased, but by year 3, the pure clover treatment out-yielded the other treatments. Except for the first year, frequent grazing resulted in more (P<0.05) DM removed than did infrequent grazing. Frequently grazed swards also had higher daily net photosynthesis after grazing than did the swards in infrequently grazed treatments, and achieved maximum levels of photosynthesis more quickly. There was no difference in photosynthesis rate, despite significant differences in clover content, between sowing rate treatments, regardless of grazing management. Initial sowing rate had a large effect on clover content in year 1, but by year 3, most of this had disappeared as clover contents rapidly converged. Frequency of grazing had its greatest effect on clover content in year 1, with infrequent grazing resulting (P<0.05) in the greatest clover contents. Grazing intensity was an important determinant of clover content in years 2 and 3, where hard grazing resulted (P<0.05) in higher clover content. Digestibility of the herbage on offer ranged from 65 to 80%, and crude protein concentrations varied from 12 to 26%. In general, frequent grazing resulted in a digestibility of 2–4 percentage units higher than infrequent grazing, with hard grazing also tending to increase digestibility. Hard grazed treatments always had high crude protein concentrations in the herbage present before grazing, and there was a slightly higher concentration in frequently grazed herbage compared with herbage that was grazed less frequently. The white clover–perennial ryegrass swards generally responded best to a combination of frequent and hard grazing. However, neither white clover nor perennial ryegrass appears to be well adapted to the combination of soils, climate, irrigation and grazing by dairy cows that occurs in the northern irrigation region of Victoria, as evidenced by a rapid influx of weeds and the general decline in productivity over the duration of the experiment.

Orchardgras 및 White clover의 단파 및 혼파 재배에서 붕소의 시용이 목초의 여러 특성에 미치는 효과 1. 목초의 생육, 개화, 뿌리 및 근류 등의 특성 변화

Orchardgrass 및 white clover의 단파 및 혼파 재배조건에서 미량요소 붕소의 시비수준별 목초의 생육, 개화, 뿌리/근류 형성, 수량, 양양성분/무기양분 및 초종간 경합지수에 미치는 영향 등을 구명하였다. 다량요소 및 다른 미량요소 양분을 동일량 시비한 조건에서 5 수준의 붕소 시비량을 달리한 시비처리를 하였다. 붕소 처리수준은 1) <TEX>$B_{0}$</TEX>; 0.0, 2) <TEX>$B_1$</TEX>; 0.2, 3) <TEX>$B_2$</TEX>;2.0, 4) <TEX>$B_3$</TEX>;6.0, 5) <TEX>$B_3$</TEX>;6.0, 5)<TEX>$ B_4$</TEX>;15.0me B/pot로 하였으며, 본 I보에서는 붕소 처리별 목초의 생육, 개화, 뿌리 및 근류의 형성, 수분관리 특성 등에 미치는 영향을 검토하였다. 1. White clover에서 붕소의 과다증상(<TEX>$B_3$</TEX>와 <TEX>$B_4$</TEX> 처리구)은 예취 차수가 진행되어 감에 따라서 경감되었고, 전반기 예취기에는 orchardgrass보다 더 심한 과다증상을 보였다. 그리고 단파보다도 혼파재부에서 과다증상이 더 심했다. 각 초종별 생육이 왕성한 시기에는 공히 붕소의 과다증상이 경감되었다. 2. Orchardgrass에서 붕소의 과다증상은 잎의 선단 부위에 황화현상, 좁은 엽폭, 적은 분얼 및 약한 줄기를 보였으며, white clover는 고엽부터 엽변의 황화현상과 백화현상, 적은 분얼수 및 포복경을 생성하는 얼자의 미 형성이 관측되었다. 3. 적합한 붕소시비(<TEX>$B_2$</TEX>)는 white clover의 뿌리생육, 근류 형성, 개화 및 화아가 양호하였고, 꽃의 생성기간이 길었으며 만개시기가 빨랐다. 그러나 혼파재배에서는 orchardgrass에 의한 억압된 생육 때문에 이 효과가 경감되었다. 4. 붕소의 시비효과는 orchardgrass보다 white clover에서 더 크게 나타났다. 혼파재배에서 white clover는 추비가 시비되지 않은 5차 예취시에는 처리구가 다른 처리구에 비해서 생육이 양호하였는데 이는 뿌리 및 근류의 형성이 더 양호한 특성에 기인된 것으로 생각되었다. 적합한 추비(특히 질소) 및 붕소의 시비는 양호한 식생을 갖는 grass-clover 혼파초지 조성에 크게 기여할 수 있는 것으로 보였다. This pot experiment was conducted to find out the effects of boron application(B<TEX>$_{0}$</TEX>; 0.0, B<TEX>$_1$</TEX>; 0.2, <TEX>$B_2$</TEX>;2.0, <TEX>$B_3$</TEX>;6.0, <TEX>$B_3$</TEX>;6.0, <TEX>$B_4$</TEX>;15.0me B/pot) on the forage performance in the pure and mixed swards of orchardgrass and white clover. This 1st part was concerned with the changes in the growth, flowers and flower buds, and roots/nodules of forages. The results obtained are summarized as follows: 1. At the <TEX>$B_3$</TEX> and <TEX>$B_4$</TEX> treatments, the B toxicity was more seriously in white clover than in orchardgrass in the first half of cutting orders, and reduced in the latter half. In white clover, it was more worsened in a mixture than in a pure culture. It was somewhat reduced at the best growth stage of each forage. 2. In orchardgrass, the B toxicity(<TEX>$B_3$</TEX>,<TEX>$ B_4$</TEX>) showed the chlorosis on leaf tips, shallow leaf, little tillers, and weak stems. Whereas it showed the chlorosis/necrosis on old leaf edge, little and weak stolons in white clover. 3. Comparing with the B deficiency(<TEX>$B_{0}$</TEX> , <TEX>$B_1$</TEX>) and toxicity(<TEX>$B_3$</TEX>, <TEX>$B_4$</TEX>), the optimum B application(<TEX>$B_2$</TEX>) influenced markedly good growth of shoot, root, nodule, and flower (flower number, blooming period, early full flower) in white clover. 4. Comparing with orchardgrass, white clover was greatly influenced by the boron application. However, this responses of white clover to boron were reduced in a grass-clover mixture with additional fertilization. It was recognized that the good forage performance in a grass-clover mixture could be regulated by the adequate applications of boron and additional fertilizers.s.

The development of Trichostrongylus colubriformis larvae on a range of herbage species or on plots of differing topographical aspect.

Five "contaminations", where faeces containing Trichostrongylus colubriformis eggs were deposited on pasture and serially recovered, were used to compare the rate of decline of faecal mass and larval development. In the first three contaminations, faeces from a common source were deposited on swards of browntop (Agrostis capillaris cv Grasslands Muster), ryegrass (Lolium perenne cv Grassland Nui), white clover (Trifolium pratense cv Grassland Tahora), or onto bare ground in the late spring, summer or autumn. The last two contaminations were done on the north facing aspect or south facing aspect of hill country pastures in summer and autumn. Number of free-living nematodes (first- and second-stage larvae (L(1) and L(2)) and soil dwelling nematodes) and third stage larvae (L(3)) recovered from faeces were counted. In spring there was a significant (P<0.01) effect of sward type on the mass of faeces remaining, with greatest mass remaining on browntop and ryegrass 28 days later, and less on bare ground and white clover. In summer there were more (P<0.05) faeces remaining on browntop than on other herbages which had little faeces remaining and which did not differ one from another. In autumn there was a rapid decline in faecal mass. All faeces were gone from white clover and ryegrass swards by day 10 and from browntop and bare ground by day 14. The number of free-living nematodes did not differ markedly between seasons, ranging from 5 to 8.5% of eggs deposited. The number of L(3) recovered was low in spring ( approximately 0.4% of eggs deposited) and did not differ between swards. In summer, more (P<0.05) L(3) were recovered from faeces deposited on swards of ryegrass and white clover than from bare ground or browntop. Most L(3) were recovered from days 7 to 14 ( approximately 1.3% of eggs deposited). In the autumn, low numbers of L(3) were recovered from browntop on day 3 and ryegrass on day 7 (0.2% of eggs deposited) with virtually no L(3) recovered from faeces placed on white clover or bare ground. There were significant (P<0.001) effects of aspect on the amount of faecal mass remaining in both summer and autumn with less faeces remaining on the south facing aspect than on the north. This was particularly evident during the summer when virtually all of the faeces were intact on the north facing aspect but only 40% was remaining on the south on day 28. In the autumn, while faeces were completely gone from both aspects by day 28 but there were less (P<0.05) faeces remaining on the south facing aspect from days 3 to 18 than from the north. There was no aspect effect in either season on the number of free-living nematodes recovered which averaged 8-11% of eggs deposited. In both seasons a greater number of L(3) were recovered from faeces on the south facing aspect than on the north, particularly 3-10 days after faecal deposition. In summer the rise in L(3) recovered in faeces was more rapid on south facing aspect than on the north but both attained a maximum level of approximately 4% of eggs deposited. In autumn on day 3 there was a rapid rise on south facing aspect to approximately 21% of eggs deposited followed by a gradual decline on day 10 while on the north facing aspect numbers of L(3) recovered only attained 10% of eggs deposited.

Voluntary herbage intake and diet selection in Scottish-Blackface ewes suckling twin lambs and grazing perennial ryegrass/white clover swards with or without protein supplementation

Mixed perennial ryegrass and white clover swards are often used as the basis of upland sheep grazing systems. This study’s objective was to examine voluntary herbage intake and diet selection in 30 lactating Scottish-Blackface ewes grazing mixed perennial ryegrass (PRG) and white clover (WC) swards supplemented with or without protein. The work was part of a wider study of nutrition and parasitology in organic sheep systems.

Long-term effects of multiple applications of nitrogen fertiliser on grazed dryland perennial ryegrass/white clover dairy pastures in south-west Victoria. 1. Nitrogen fixation by white clover

A 3-year experiment determined the impact of multiple applications of different rates of nitrogen (N) fertiliser, applied over autumn and winter in 1997, 1998, and 1999, on N2 fixation in grazed dryland perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) dairy pastures. Four treatments replicated 3 times in a randomised block design comprised: 0 N (A); 3 applications of 25 kg N/ha (B); 3 applications of 50 kg N/ha (C); and 3 applications of 75 kg N/ha (D). Urea (46% N) was the N source and applications were from autumn to late winter. 15N abundance methods, based on herbage samples, were used to estimate N2 fixation. Percentage N derived from the atmosphere (%Ndfa) through white clover N2 fixation decreased as the rate of N fertiliser application increased during 1997, but remained unaffected by treatment during 1998 and 1999. Slight decreases in %Ndfa, associated with an increase in soil nitrate, were offset by the positive association between clover dry matter (DM) and soil ammonium. The amount of N2 fixed by white clover decreased from 43 kg N/ha.year (A) to 23 kg N/ha.year (C) during 1997. The amount of N2 fixed by white clover during 1998 and 1999, however, was unaffected by increasing rates of N fertiliser application and averaged 17 and 12 kg N/ha.year in 1998 and 1999, respectively. White clover sward composition (percentage of DM) was unaffected by the rate of N fertiliser application. The average white clover composition across treatments declined from 23% DM in 1997 to 12% DM in 1999. It is concluded that the DM yield production of dryland perennial ryegrass/white clover dairy pastures is likely to be restricted by available soil N, as the amount of N2 fixed annually by clover is low (approx. 20 kg N/ha.year). There is, therefore, scope to supplement pasture N nutritional requirements with fertiliser N. Further, application of N fertiliser may restrict the ability of white clover to fix N2; however, under the grazing management adopted, N fertiliser had no effect on the percentage of white clover.