Effects of perennial ryegrass cultivar, duration of lock up and nitrogen fertiliser application on dairy pasture dry matter yield and quality for silage in south-western Victoria

2001 ◽  
Vol 41 (1) ◽  
pp. 45 ◽  
Author(s):  
J. L. Jacobs ◽  
F. R. McKenzie ◽  
G. N. Ward ◽  
G. Kearney

A study in south-western Victoria determined effects of 3 perennial ryegrass (Lolium perenne L.) cultivars (Vedette, Impact and Nevis) with differing maturities, duration of lock up and nitrogen (N) application on the dry matter yield and nutritive characteristics of pasture for silage. Treatments were cultivar (3), N (0 and 50 kg N/ha) and duration of lock up (5–10 weeks) arranged in a completely randomised design in 3 by 5 m plots replicated 3 times. Plots were mown to a uniform height (5 cm) on 14 September 1998 (first day of lock up) and 1 week later N was applied as urea (46% N) at either 0 or 50 kg N/ha to the respective plots. Weekly sampling commenced on 19 October (week 5 of lock up), and continued until 23 November. For each treatment and harvest date, dry matter yield and botanical composition were determined, and samples of total pasture and the ryegrass fraction were collected and chemically analysed for dry matter digestibility, concentrations of crude protein, neutral detergent fibre, water-soluble carbohydrates and minerals. Metabolisable energy was derived from dry matter digestibility. All pasture types were predominantly ryegrass (>90%) with no differences in the nutritive characteristics of total pasture swards or the respective ryegrass fraction. Nitrogen at 50 kg N/ha significantly (P<0.05) increased dry matter yield for all cultivars. Metabolisable energy (MJ/kg DM) of the pasture declined with time for all treatments, with Vedette having a significantly (P<0.05) greater rate of decline than the other cultivars. Vedette reached early ear emergence about 3 weeks earlier (week 7) than the other cultivars. The harvestable metabolisable energy yield (MJ/ha) at ear emergence was highest for Impact, followed by Nevis and Vedette. In conclusion, there is potential to use later-maturing cultivars of ryegrass in south-eastern Australia to allow for later harvesting of forage for silage, while maintaining metabolisable energy and maximising dry matter yields. Furthermore, the use of N fertiliser can also increase dry matter yields without impinging on pasture quality provided the time between N application and harvest date does not exceed 5–6 weeks.

1998 ◽  
Vol 38 (3) ◽  
pp. 219 ◽  
Author(s):  
J. L. Jacobs ◽  
F. R. McKenzie ◽  
S. E. Rigby ◽  
G. Kearney

Summary. This study aimed to define the effect of differing rates of nitrogen application and lock up length on harvested material for silage in south-western Victoria. At 2 sites in south-western Victoria, 140, 3 by 2 m plots of predominantly perennial ryegrass pasture were randomly allocated, within 4 replicate blocks. Five nitrogen fertiliser rates (0, 25, 50, 75, 100 kg N/ha) in combination with 7 lock up lengths were randomly allocated to the 35 plots within each replicate. Nitrogen was applied 1 week after initial lock up (September 10, site 1; September 12, site 2) and harvesting commenced 3 weeks after initial lock up. For each treatment and harvest date, dry matter yield and botanical composition were determined and samples of total pasture and the ryegrass fraction were collected and chemically analysed for dry matter digestibility, crude protein, neutral detergent fibre, water-soluble carbohydrates and mineral content. Metabolisable energy was derived from dry matter digestibility. Increasing rates of nitrogen increased herbage dry matter yield regardless of length of lock up. The yield response was greatest 8 weeks after initial lock up at both sites (site 1, 26 kg DM/kg N; site 2, 14.9 kg DM/kg N). Subsequent regrowth of pasture was increased by nitrogen application over shorter lock up lengths (weeks 3 and 4). Botanical composition was unaffected by treatment during the harvesting period or in the subsequent autumn. Application of nitrogen gave rise to a linear increase in pasture metabolisable energy and crude protein content at both sites until week 5. Thereafter, this response diminished and by week 8 there was a decrease in metabolisable energy and crude protein content. Neutral detergent fibre content was relatively unaffected by nitrogen application until week 8 of the study, at which point there was a linear increase. Application of nitrogen reduced the water-soluble carbohydrate content of pastures throughout the sampling period. It is concluded that application of nitrogen to a mixed sward locked up for silage can increase dry matter yield and, provided pasture is harvested before ryegrass ear emergence, can also have a positive effect on metabolisable energy and crude protein. Given that the decision for removing paddocks from the grazing rotation is based upon pasture growth and stocking rates, the use of nitrogen fertilisers on higher stocked farms could lead to increased dry matter yield over shorter lock up periods. On farms with lower stocking rates shorter lock up periods may allow for pastures to be returned to the grazing rotation earlier, or provide the opportunity for a second harvest of pasture for silage.


2003 ◽  
Vol 43 (2) ◽  
pp. 121 ◽  
Author(s):  
W. J. Fulkerson ◽  
K. Slack

A cut plot study was undertaken on the subtropical north coast of New South Wales, Australia, to determine the effect of defoliation height and redefoliation interval on dry matter yield and persistence of perennial ryegrass (Lolium perenne L.) pastures. The pasture was established on 7 April 1998 and plots were irrigated to replace evapotranspiration loss. The study was a completely randomised block design with plots of 2 by 1 m and treatments replicated 3 times. In winter (commencing 13 July) plots were defoliated to 20, 50 or 120 mm stubble height and either not redefoliated or redefoliated at 3, 6 or 3 and 6 days after initial defoliation. In spring (commencing 28 October) plots were redefoliated as for winter but only to 50 mm stubble height. After imposition of the redefoliation treatments, the plots were allowed to regrow until the non-redefoliated treatments had regrown 3 new leaves per tiller (subsequently referred to as a regrowth cycle) and then again defoliated (regrowth cycle 1). Plots cut in winter were then halved with one half (A plots) continuing to be subject to the redefoliation treatment for 4 more regrowth cycles until regrowth cycle 1 in spring was completed on 24 November, while the other half (B plots) were a carryover comparison of redefoliation treatment in regrowth cycle 1. Both A and B plots continued to be subjected to the same defoliation height treatments as imposed in regrowth cycle 1. From 24 November to 30 March 1999, plots were defoliated at 50 mm height each time 3 new leaves per tiller had regrown.Plots defoliated to 20 or 50 mm height during regrowth cycle 1 in winter yielded 21% more dry matter than plots cut to 120 mm height while redefoliation at 6 or 3 and at 6 days produced 14% less dry matter than plots not redefoliated or redefoliated at 3 days. Continued redefoliation at 6 days (comparison within A plots) reduced dry matter yield by 63% compared with no redefoliation or redefoliation at 3 days, but only in plots defoliated to 20 or 50 mm height.Plant density in the autumn (March 1999) of the year after establishment was positively related to defoliation height over regrowth cycles 1–5 of the previous year (35, 55 or 77 plants/m2 for plots defoliated at 20, 50 or 120�mm, respectively). Plant density of plots not redefoliated or redefoliated at 3 days over regrowth cycles 1–5 was 63% higher (70 plants/m2) than for the other treatment combination (43 plants/m2) at P = 0.07 level of significance.Plants cut to 20 or 50 mm stubble height at the commencement of regrowth cycle 1 in winter had a stubble water-soluble carbohydrate content of 5.2%, decreasing to 2.3% at day 6 post-defoliation. The water-soluble carbohydrate content of plants cut to 120 mm were initially higher at 8% and fell to only 6.4% by day 6.The redefoliation treatments imposed in this study were designed to simulate the regrazing of regrowth shoots in an extended grazing bout at various defoliation heights. The results confirm the negative effects of redefoliation, at 6 days in the winter to spring period, on both dry matter yield and plant survival over the subsequent summer in the subtropics. In contrast to winter, redefoliation in late spring had no effect on dry matter yield or plant density. The results also indicate a compromise between the benefits of more lax grazing for persistence and harder grazing for pasture utilisation.


1998 ◽  
Vol 38 (2) ◽  
pp. 131 ◽  
Author(s):  
J. L. Jacobs ◽  
S. E. Rigby ◽  
F. R. McKenzie ◽  
G. N. Ward ◽  
G. Kearney

Summary. At 2 sites in south-western Victoria, 132 plots of predominantly perennial ryegrass pasture were randomly allocated, within 4 replicate blocks, to each of 3 lock up dates (L1, L2, L3) by 12, 12 or 9 harvest times. Harvesting commenced 2 weeks after initial treatment lock up with L1 and L2 being harvested 12 times (weekly intervals) and L3, 9 times. Lock up dates were 15 August (L1), 5 September (L2) and 26 September (L3) at site 1 and 17 August (L1), 7 September (L2) and 28 September (L3) at site 2. For each treatment and harvest date, dry matter yield and botanical composition were determined and samples of total pasture and the ryegrass fraction were collected and assessed for dry matter digestibility, crude protein and neutral detergent fibre. Dry matter yield was measured from the start of L1 (site 1, 15 August; site 2, 17 August) until the final harvest date of L3 (site 1, 12 December; site 2, 14 December). At site 1, L3 produced higher dry matter yields than L1 and L2 at comparable lengths of lock up time, whilst there were no differences at site 2. Over the total experimental period (site 1, 15 August–12 December; site 2, 17 August–14 December) there were no differences in total dry matter yield (t/ha) between treatments at either site (site 1—L1 5.79, L2 6.43, L3 5.94; site 2—L1 6.68, L2 5.07, L3 5.73). Treatments had little effect on botanical composition at either site when compared at the same time after lock up, both during the harvesting period or in the subsequent autumn. Pasture metabolisable energy and crude protein all declined with increasing length of lock up whilst neutral detergent fibre content increased, changes which were similar for both the total pasture and the ryegrass fraction. The metabolisable energy of pasture in L1 and L2 was higher than that of L3 at least until week 8 at both sites. Initial crude protein values were higher for L1 and L2 than for L3 at site 1, whilst at site 2, L1 had higher values than either L2 or L3. Although longer lock up periods produced more herbage, if conserving forage is to be an integral component of managing surplus spring pasture, then dairy farmers should aim to produce high quality pasture for forage conservation. This will be achieved through shorter lock up periods and harvesting pasture no later than early ear emergence in the ryegrass fraction of the sward. This management will reduce dry matter yields, but allow more flexibility for maintaining intensive grazing practices through the spring period. The decision about when to lock up pasture will depend on both plant growth rates and animal feed requirements.


1982 ◽  
Vol 99 (1) ◽  
pp. 153-161 ◽  
Author(s):  
D. A. Davies ◽  
T. E. H. Morgan

SUMMARYHerbage characteristics of perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.) and timothy (Phleum pratense L.) pastures were obtained whilst rotationally grazed by ewes and their single lambs at a fixed stocking rate of 25/ha on an upland site (305 m O.D.) in mid-Wales. Drymatter production of cocksfoot averaged 32·1 kg/ha/day over the 3-year duration of the trial (1975·7) and was 13·3 kg/ha/day lower than that of the other three grass species. This resulted in a 8 kg/ha/day reduction in dry-matter intake on cocksfoot; this was significantly lower (P < 0·05) than that achieved on the other grasses, which were similar to one another around 36 kg/ha/day.In vitro digestibility of the herbage ranked in the order perennial ryegrass > timothy = cocksfoot > tall fescue. Intake of digestible organic matter (DOMI) was lower on cocksfoot than on perennial ryegrass and timothy. Differences were also detected in crude protein, water-soluble carbohydrates and sodium composition between species.Dry-matter intake was positively correlated with herbage growth rates (r = 0·95, P < 0·001) but not to digestibility of herbage on offer (r = 0·18). Both ewe and lamb live-weight gains were positively related to intake of dry matter and DOMI.Reference is made to comparative yield data between the grasses obtained under cutting trials. In the 2nd and 3rd harvest years (1967–1967) growth rates in the grazing experiment were 76, 61, 81 and 80% of the 66·2, 66·7, 67·8 and 65·0 kg D.M./ha/day obtained under a cutting regime on perennial ryegrass, cocksfoot, tall fescue and timothy swards respectively. This illustrates the danger involved in assessing the potential of grasses based on such information.The results are discussed in relation to the value of the species for use under grazing in the uplands.


2001 ◽  
Vol 41 (6) ◽  
pp. 743 ◽  
Author(s):  
J. L. Jacobs ◽  
G. N. Ward ◽  
A. M. McDowell ◽  
G. A. Kearney

Factors associated with turnip dry matter yield, metabolisable energy and crude protein were investigated in 266 turnip forage crops on 142 dairy farms in south-western Victoria during spring 1999 and summer 2000. Factors measured were primary cultivation method, secondary cultivation method, soil texture, soil temperature and moisture at sowing, seedbed preparation, turnip variety, sowing method, sowing rate, rolling post-sowing, harrowing post-sowing, seedling establishment, insect damage, water received, phosphorus and nitrogen application. The average date for the commencement of seedbed preparation was early October, although the range was from mid-March until mid-December. Sowing dates ranged from mid-September to mid-December, with an average of mid-October. The most common turnip variety sown was Barkant, followed by Mammoth Purple Top, Vollenda and Rondo. Growing periods ranged from 8 to 23 weeks, with the majority of crops grazed from 8 to 15 weeks. The average dry matter yield was about 5 t DM/ha, with values ranging from 0.4 to 19.2 t DM/ha. The average metabolisable energy content of turnips was 13.7 MJ/kg DM with values ranging from 11.3 to 14.6 MJ/kg DM. The metabolisable energy of roots was on average higher than the leaf component of the plants (14 v. 13.5 MJ/kg DM). Conversely, crude protein content of leaves (15.4%) was higher than in the root fraction (13.9&percnt;). The average neutral detergent fibre content of turnips was 22.5% with values ranging from 16.9 to 30.5%. The water-soluble carbohydrate content of the leaf component ranged from 1.1 to 26.8% with an average of 14.7%, while starch content of the root component ranged from 0.3 to 38.8% with an average content of 16.9%. The average cost of growing a turnip crop was &dollar;485/ha or &dollar;133 t DM. Total, leaf and root dry matter yield as well as metabolisable energy and crude protein were analysed by a mixed effects model (with factors fixed and farms and paddocks random). Factors that were associated with total dry matter yield were total water received, soil temperature and moisture at sowing, seedling density, method of secondary cultivation, soil type and insect damage. The application of nitrogen fertiliser had the greatest association with turnip crude protein content. In conclusion the findings of this study indicate potential ways to increase the dry matter yield of turnips grown in south-western Victoria. Given the current average dry matter yields and cost of growing turnips, purchasing cereal grain may be a viable alternative. An increase in average dry matter yield would make the choice of growing turnips as a feed for lactating dairy cows a more profitable option.


2002 ◽  
Vol 42 (5) ◽  
pp. 541 ◽  
Author(s):  
J. L. Jacobs ◽  
F. R. McKenzie ◽  
G. A. Kearney

A study determined the effects of differing rates of nitrogen fertiliser [0 (N0), 25 (N1), 50 (N2) and 75�kg N/ha (N3)] during late autumn (T1) and mid- (T2) and late (T3) winter on the nutritive characteristics of perennial ryegrass over a 28-day period after each application. All nitrogen applications were made to pastures with a post-grazed residual mass (dry matter) of 1400 kg/ha. Changes in metabolisable energy followed similar patterns for all treatments within a given period. Metabolisable energy was highest in T1, ranging from 11.8 to 13.1 MJ/kg dry matter, followed by T2 (11.5-12.3 MJ/kg dry matter) and T3 (10.6-11.5 MJ/kg dry matter). Changes in crude protein for all treatments at each application time were similar, irrespective of rate of nitrogen application. At the commencement of treatment application times, the existing crude protein content (%DM) was highest in N3 (T1�19, T2 23, T3 22), followed by N2 (T1 18, T2 21, T3 21), N1 (T1 17, T2 20, T3 20) and N0 (T1 16, T2 17, T3 18). During both T1 and T2, neutral detergent fibre content decreased by 4 percentage units and increased by a similar amount during T3. Generally, neutral detergent fibre content (%DM) was highest during T3 (53-58%), followed by T2 (45-54%) and T1 (43-49%). Water-soluble carbohydrate content (%DM) increased during all treatment periods with the highest level observed during T1 (18-31%) followed by T2 (3-14%) and T3 (1-6%). Nitrate content (measured as nitrate-nitrogen) decreased throughout T1, primarily due to dry conditions, while during T2, levels for N3 and N2 were significantly (P<0.05) higher than for N1 and N0 following nitrogen fertiliser application. During T3, nitrate content increased for all treatments throughout the 28-day period, with highest nitrate levels being observed during T3. The effect of applied nitrogen on mineral content was variable within and across treatment periods. The study indicates that nitrogen fertiliser did not affect metabolisable (apart from N3 elevating metabolisable energy during T3), neutral detergent fibre or water-soluble carbohydrate contents of perennial ryegrass during the 28 days after nitrogen application, but increased crude protein content. Also, nitrogen fertiliser elevated nitrate content in perennial ryegrass. While the elevated nitrate content observed may result in subclinical effects, these levels are not considered fatal for dairy cows. Crude protein content was generally above 20% of dry matter throughout the study and close to 30% of dry matter for short periods during T2. Minimising the effect of excess nitrogen ingested by the grazing animal may require appropriate supplementation of low crude protein containing feeds such as cereal grains. It is argued that the effects of rain and temperature, which impact on soil nitrogen mineralisation, may have a greater influence on perennial ryegrass nitrate content than nitrogen fertiliser.


1998 ◽  
Vol 38 (8) ◽  
pp. 821 ◽  
Author(s):  
K. F. Smith ◽  
R. J. Simpson ◽  
R. N. Oram ◽  
K. F. Lowe ◽  
K. B. Kelly ◽  
...  

Summary. Two lines of perennial ryegrass (Lolium perenne L.), cv. Aurora and breeding line Ba 11351, from the United Kingdom with elevated concentrations of water-soluble carbohydrates in the shoot were compared with the standard cultivars, Ellett, Vedette and Kangaroo Valley, in pure grass swards under irrigation at Kyabram, Victoria, and Gatton, Queensland, and under natural rainfall at Condah, Victoria, during 1995–97. Near infrared reflectance spectroscopy was used to predict the water-soluble carbohydrate, crude protein, in vitro dry matter digestibility, neutral and acid detergent fibre, and Klason lignin concentrations of the perennial ryegrass herbage. Herbage yield and water-soluble carbohydrate differed between cultivars at each site at most harvests, with the high water-soluble carbohydrate lines usually yielding less and having higher water-soluble carbohydrate concentrations than the 3 standard cultivars. However, the high water-soluble carbohydrate lines also had higher water-soluble carbohydrate concentrations at harvests where their yield was equal to the standard cultivars. The other nutritive value traits differed significantly at more than half of the 32 harvests: the high water-soluble carbohydrate lines had higher crude protein and dry matter digestibility, and lower neutral detergent fibre, the neutral detergent fibre containing less acid detergent fibre and lignin than did the standard cultivars. The high water-soluble carbohydrate lines were more susceptible to crown rust during spring and summer than the standard cultivars at Kyabram and Gatton: heavy infections reduced yield, water-soluble carbohydrate, dry matter digestibility and crude protein. Higher water-soluble carbohydrate may depend on only a few genes, as does rust resistance and it seems likely that high yielding, high water-soluble carbohydrate cultivars can be developed by recombination and selection.


1998 ◽  
Vol 38 (2) ◽  
pp. 139 ◽  
Author(s):  
J. L. Jacobs

Summary. Factors associated with silage quality were investigated on 140 dairy farms in western Victoria. The management factors measured were date of lock up, date cut, length of lock up, duration of wilting, raking and tedding during wilting period, rainfall during wilting period and the type of silage made. Pasture variables measured at harvesting included percentage composition (ryegrass, legume, other grasses and weeds), dry matter of pasture, metabolisable energy, crude protein, neutral detergent fibre and water-soluble carbohydrate of the pasture, and dry matter yield of the pasture. The average lock up time of pasture for silage was mid September, although the range was from late July to early November. The length of lock up varied from 16 to 91 days with a mean value of 49 days and pastures were on average harvested in early November. Ryegrass on average accounted for 61%, legumes and other grasses accounting for a further 15% each and weeds about 5%. The range in quality of pasture at harvesting was highlighted by the range in metabolisable energy (8.9–11.3 MJ/kg DM) and crude protein (10.2–20.4%) values. Wilting times varied from 0.5 to 15 days with the biggest range being observed in pastures used for baled silage. All factors were regressed against final silage metabolisable energy and crude protein. Factors which had the greatest effect on final silage metabolisable energy were date of cutting, length of lock up, type of silage, the interaction between type of silage and length of lock up, length of wilting and mechanical treatment during the wilting period. Final silage crude protein was most strongly associated with date of cutting, crude protein content of the pasture and mechanical treatment during the wilting period. Mechanical treatment during the wilting period had the greatest influence on silage quality. Other options to improve silage quality such as cutting earlier or reducing wilting periods may not be possible or economically viable.


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