S23 Perennial Ryegrass Research Articles

Silage and milk production: a comparison between three grass silages of different digestibilities

AbstractThree first‐harvest grass silages made from S23 perennial ryegrass cut on 25 May, 13 June and 25 June, and termed early, medium and late silages respectively, were compared in a 16‐week feeding experiment with fourteen Ayrshire cows. The early, medium and late silages had D‐values of 71·2, 65·0 and 62·5 respectively. The early silage was offered alone, whereas the medium and late silages were supplemented with a concentrate containing 208 g crude protein per kg DM at rates of 2, 3 and 4 kg per 10 kg milk. Silage DM intake was 12·8 kg per cow per d on the early silage treatment, and decreased progressively as concentrate intake increased on the other silage treatments. The mean daily milk yields were 16·0 kg per cow in the early silage treatment, 17·0, 18·4 and 20·4 kg per cow in the medium silage treatments, and 16·8, 18·1 and 20·2 kg per cow in the late silage treatments on the 2‐, 3‐ and 4‐kg concentrate treatments respectively. Fat concentration in the milk was not affected significantly by treatment, whereas the CP and SNF concentrations increased progressively and significantly as supplementary feeding increased. From the relationship between milk yield and concentrate intake it was calculated that the medium and late silages required a daily concentrate supplement of 2·1 kg DM per cow to give the same daily milk yields as the early silage.

Effects of rates and times of application of starter dressings of nitrogen fertilizer to surface sown perennial ryegrass‐white clover on hill peat

AbstractThe effects on clover and grass growth of five levels of ammonium nitrogen (NH4‐N) applied before sowing, at sowing and after nodule initiation have been investigated. A pot experiment in which S184 white clover was grown in a peat soil showed that NH4‐N up to 688 mg N per pot (approx. equivalent to a field rate of 120 kg ha‐1 N) applied before sowing and at sowing did not affect clover growth. N‐fixing activity (C2H2‐reduction), on the other hand, was reduced progressively up to the highest level (688 mg N per pot). Application after nodule initiation increased growth relative to the zero‐N treatment at all levels of application. Maximum growth and N fixation occurred at 516 mg N per pot where the DM yield was 70% higher than in the absence of added N. A field trial in which S184 clover and S24 perennial ryegrass were surface sown on to a peat soil showed an increase in grass and clover growth in the first year in response to 120 kg ha‐1 N applied at sowing. Grass growth alone was increased at 120 kg ha ‐1 N applied 40 d before sowing. Lower rates of application before sowing and at sowing did not affect clover or grass growth. The effect of the delayed application of NH4‐N on legume growth was less marked than that in the pot experiment, 90 kg ha‐1 N stimulating clover growth by 40% in the first year. The effect was however different from that in the pot experiment, in that, whilst 30kg ha‐1 N increased N fixation relative to the zero‐N treatment, plants exposed to higher levels showed a depression in N‐fixing capacity. N‐fixation was correlated with nodule numbers in the delayed NH4‐N application, the closest correlation being with the number of multilobed nodules which was highest at 30 kg ha‐1 N and lowest at 120 kg ha‐1 N.It is suggested that circumstances exist when the use of a relatively low starter N dressing (20–60 kg ha‐1 N) at sowing would not increase clover or grass growth in the early stages of the establishment of a hill reseed. Under such circumstances higher rates of application (100 kg ha ‐1 N), preferably delayed until the seedlings are in a position to take up the nitrogen rapidly, would have the greatest effect.

The effect of daily herbage allowance and sward characteristics upon the ingestive behaviour and herbage intake of calves under strip‐grazing management

AbstractMeasurements of herbage intake and ingestive behaviour were made on British Friesian calves 4–9 months old, which were strip‐grazed on swards of S24 perennial ryegrass at three (Experiment A) or four (Experiment B) levels of daily herbage allowance in three (A) or four (B) 12‐d periods. Herbage intake declined by approx. 18% as daily herbage allowance was reduced from 90 to 30 g DM per kg LW in both experiments, but the relationship between intake and allowance was not consistent between periods.Bite size and rate of biting were greater in calves on low than on high allowances after entry to a new strip of herbage but the positions were reversed towards the end of grazing. Reduced herbage intakes at low allowance resulted from reductions of approx. equal magnitude in bite size, rate of biting and grazing time, though not all of these effects were significant. It is suggested that these responses result from the increasing difficulty of prehending and ingesting herbage as swards are grazed down. The calves at low herbage allowances did not increase grazing time, probably because their behaviour was conditioned by anticipation of a new allowance of herbage.Bite size and daily herbage intake were greater on a spring sward than on an autumn sward, but within experiments herbage intake was not consistently related to any of the sward characteristics measured.

Silage and milk production: comparisons between grass silage of three different chop lengths

AbstractThree grass silages of different chop lengths made from a uniform sward of S23 perennial ryegrass were compared in four experiments including a feeding experiment with twelve lactating cows, an eating behaviour study, a rate of passage investigation and a selection trial. The silages had median chop lengths of 9·4, 17·4 and 72·0 mm, termed short, medium and long, with pH values of 3·93, 3·94 and 4·17 and D‐values of 65·9, 65·2 and 64·4 respectively.The daily intakes of silage DM and the daily milk yields increased as silage chop length decreased. The milk yield response to shorter chopping was significant with a supplement of groundnut but not significant with a supplement of sugar‐beet pulp. Chop length had small and generally non‐significant effects on milk composition.Eating and ruminating times expressed as min per kg DM decreased as silage chop length decreased but the retention time of the silage residues in the entire digestive tract was not significantly affected by chop length. When offered simultaneously, the intakes of the individual silages were 52·2, 31·9 and 15·9% of the total DM intake for the short, medium and long treatments respectively.Although silage with a chop length of 9 mm had nutritional advantages over longer silages, it is concluded that the mechanical and economic aspects of silage making must be considered fully when defining optimum chop length.

The effects of variation in sward characteristics upon the ingestive behaviour and herbage intake of calves and lambs under a continuous stocking management

AbstractGroups of calves and lambs grazed on plots of S23 perennial ryegrass, in successive periods of 2, 2 and 3 weeks, at stocking rates which resulted in a slow change in herbage mass on each plot and measurements were made of ingestive behaviour (biting rate, bite size and grazing time) and herbage intake.As the green herbage mass was progressively reduced from approx. 3000 to 1000 kg OM per ha between periods, biting rate and grazing time increased, but insufficiently to offset the rapid fall in bite size so that herbage intake declined by 24% and 39% for calves and lambs respectively. Patterns of response were similar in calves and lambs, though in all parameters except biting rate the lambs appeared to be more sensitive than the calves to changes in sward conditions and there was no evidence that lambs were better adapted to grazing on short swards than calves.Intake increased in both calves and lambs up to levels of 2500–3000 kg green OM per ha, though this response may have been attributable in part to the reinforcing effects of increasing herbage mass and diet digestibility. Lambs consistently selected a more digestible diet than calves.Both calves and lambs increased grazing time substantially in response to limiting sward conditions, in contrast to results in earlier strip‐grazing trials with calves, thus supporting the suggestion that the lack of response under strip‐grazing is a characteristic of the management imposed.

Nitrogen studies in Lolium perenne grown for seed III. The effect of nitrogen and water stress

AbstractThe effects of water and nitrogen (N) availabilities and their possible interactions on the seed yield and yield components of S23 perennial ryegrass grown in pots in the glasshouse were investigated. Increasing the N fertilizer from 0 to 5 g per pot more than doubled the seed yield but no further increase in seed yield was found by increasing N fertilizer from 5 to 10 g per pot. The main effect of increasing water availability was to increase both seed and straw yield. When N had been applied, accumulated evapotranspiration was linearly related to seed and straw yield. The component of yield having the greatest effect on yield was the number of fertile tillers and, although both N and water availability affected this component, N had the larger effect. Implications of these responses are discussed in relation to the potential yield of the crop and to the field situation.

The influence of herbicides, nitrogen fertilizer, seed rate and method of sowing, on the establishment and long‐term composition of a perennial ryegrass ley.

Summary:Changes in ihe species composition of a ryegrass pasture were examined over a 2 year period from a spring establishment. Seed of S23 perennial ryegrass was sown in main plots, eilher broadcast or drilled, at rates of 15, 25 or 35 kg/ha in a field experiment at Oxford. The whole area was oversown withfour weed grasses (Agrostis siolonifera.Holcus lanatus. Poa annua and P trivialis). Five cultural and three herbicide treatments were applied across the plots. These consisted of three levels of nitrogen (0. 50 and 100 kg N per ha), two companion species (Italian ryegrass and white clover) and 2.4‐D, benazolin and methabenzihiazuron applications.Ten weeks after sowing, broad‐leaved weeds accounted for nearly half the lotal dry‐matter yield, except where controlled by the three herbicides. Grass yields were nol increased by herbicide treatment. The only cultural treatment checking broad‐leaved weeds was ihe 35 kg/ha seeding rale.Seven months after sowing, the only treatment which had decreased the abundance of weed grasses was melhabenzthiazuron especially againsi A. stolonifera and Poa spp. Two years afler sowing, perennial ryegrass had only 34% ground cover and had been replaced largely by H. lanatus (38%), Poa spp, (15%) and A. stolonifera (7%), Where methabenzthiazuron had been used the ryegrass ground cover was 48%. with less P. trivialis and A. stolonifera. but H. lanatus was nol altered. White clover decreased H. lanatus cover.In two supplementary pot experiments, methabenzthiazuron sprayed pre‐emergence damaged perennial ryegrass unless the seed was covered with at least 4 mm of soil. Only H. lanatmand F. rubra out of sixteen grasses were relatively resistant to methabenzihiazuron when applied at ihe tillering stage, confirming that this herbicide has potential for preventing the ingress of many unsown grasses in new leys.

Silage and milk production: a comparison between soya, groundnut and single‐cell protein as silage supplements

AbstractGrass silage made in May from S24 perennial ryegrass was offered ad libitum to twelve Ayrshire cows in a 12‐week feeding experiment. The silage had a DM concentration of 217 g kg ‐1, contained 147 g crude protein per kg DM and had a D‐value of 64·6. In addition each cow consumed 1 kg hay per d plus concentrate supplements of dried sugar‐beet pulp with (A) soya bean meal, (B)‘Pruteen’, a single‐cell protein (C) groundnut cake. The three concentrate supplements each contained 250 g crude protein per kg DM and were offered at the rate of 2·9 kg per 10 kg milk. The daily intakes of silage DM were 8·38, 7·94 and 7·49 kg on treatments A, B and C, respectively, with the extreme values being significantly different. The mean daily yields of milk on treatments A and B were both 16·2 kg per cow, and were significantly higher than the yield of 15·2 kg per cow on treatment C. The fat and lactose contents of the milk on the three treatments were not significantly different, but the CP content on treatment C was significantly lower than that on the other treatments. It is concluded that soya bean meal and‘Pruteen’were superior to groundnut cake as a protein supplement in a silage‐based ration.

Regrowth of ryegrass swards subject to different cutting regimes and stocking densities

AbstractA cutting experiment was carried out on a sward of S23 perennial ryegrass to study the effect of different defoliation regimes on regrowth and the factors affecting regrowth. The defoliation frequencies and intensities encompassed the range commonly found on continuously stocked pastures. The defoliation regimes produced swards of contrasting growth form with regrowth characteristics which differed in respect of senescence loss, fall in water‐soluble carbohydrate concentration, residual leaf area index, photosynthesis per unit leaf area index and photosynthesis per unit area of land. Regrowth was most closely related to the latter. These results were used to interpret data for net canopy photosynthesis of continuously grazed pastures.

Survivor populations of S23 perennial ryegrass from zero‐grazed and set‐stocked swards

AbstractPerennial ryegrass tillers were collected from intensively used set‐stocked and zero‐grazed leys and from an old permanent pasture, grown on and compared at 30 cm spacing. All swards except the permanent pasture had been sown with cv. S23 and were of known age, ranging from 6 months to 11 years from sowing.Each genotype was scored for date of inflorescence emergence, and subsequently in vitro dry matter digestibility (DMD), D‐value of green leaf and the ratio of leaf dry weight: stem dry weight were determined.Both DMD and D‐value declined significantly in green leaf samples of populations from the older zero‐grazed swards but no significant changes were detected in populations from set‐stocked swards. In set‐stocked populations there was a shift towards later flowering.In zero‐grazed populations there was a consistent increase in the amount of leaf relative to stem with the age of the sward from which the plants were sampled. The survivor plants were more prostrate and leafier and it is suggested that under zero grazing, where cutting was to a uniform height, plants of this form were less severely defoliated and thus at a selective advantage.

Nitrogen studies in Lolium perenne grown for seed. II. Timing of nitrogen application

AbstractThe effects of applying nitrogen at different growth stages to S24 and S23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1971 to 1976. These varieties of ryegrass were found to be insensitive to timing of nitrogen application from apex initiation to the stage when ears first emerged. However, if nitrogen application was delayed until about 30% or more of the ears had emerged, yields were lower compared with earlier applications, this effect being significant when nitrogen was delayed until 70–80% ear emergence because of a decrease in both numbers of fertile tillers and number of seeds per unit area. No advantages were found for splitting nitrogen applications between apex initiation and ear emergence.

A comparison of continuous grazing systems for milk production

AbstractIn two experiments conducted with Ayrshire dairy cows in 1974 and 1975 on swards of S23 perennial ryegrass, four systems of continuous grazing were investigated. The leys received 345 and 370 kg ha‐1 fertilizer nitrogen in 1974 and 1975 respectively and were stocked at the rate of five cows per ha. In 1974, a comparison was made between two systems which either integrated silage making with, or separated it from, the continuous grazing. The provision of a silage aftermath in late July increased milk yield after that time, but had no significant effect on milk yield over the 19‐week experimental period. In 1975, a comparison between weekly and monthly applications of fertilizer N showed no significant differences between milk yields in a 20‐week period. The feeding of supplementary concentrates from late July onwards significantly increased milk yield. The treatments in both years had only small and mainly non‐significant effects on milk composition. On average, excluding the concentrate treatment, the annual output of milk was 10,800 kg ha‐1 using spring‐calved cows.

The value of timothy (Phleum pratense L.) in ryegrass — timothy mixtures managed to simulate intensive grazing

AbstractThe performance of timothy in mixtures with perennial ryegrass was assessed under a simulated intensive grazing management over two harvest years in 1974–75. Three seed rates of S23 perennial ryegrass were factorially combined with three rates of Scots timothy and compared with pure stands of each grass. All were sown with Huia white clover. When cut six times at monthly intervals and with an annual N input of 350 kg ha−1, there were no significant differences in total DM production in either year. The 2‐year mean DM yield for the nine mixtures and six pure swards was 9·77 t ha−1 (range 9·34–10·16). Compared with the pure ryegrass swards, in both years the ryegrass‐timothy mixtures produced earlier spring growth but were significantly lower yielding at the second cut. Over the first five cuts the proptortion of timothy in the three mixtures with 22·4 kg ha−1 ryegrass seed averaged 26% in the first year and 37% in the second. Corresponding calculated mean DM yields of timothy were 2·75 and 3·00 t ha−1.It is concluded that an early timothy variety is capable of competing with a late‐heading perennial ryegrass in frequently cut swards managed to simulate intensive grazing. The strong development of timothy in the dry summer of 1975 suggests that in mixtures of late perennial ryegrass varieties, an early variety of timothy should be beneficial for its spring growth in grazed swards.

Silage and milk production: a comparison between additives for silage of high digestibility

AbstractThree grass silages made in early June from S23 perennial ryegrass were compared in a 16‐week feeding experiment with twelve Ayrshire cows. The silages were made from uniform herbage which received either formic acid (‘Add‐F’) at the rate of 201 t−1, or a formalin‐sulphuric acid mixture (‘Syiade’) at rates of 2.0 and 4.4 1 t−1. The silages were offered ad libitum either alone or supplemented with a cube containing 38% CP in the DM at the rate of 1.4 kg per 10 kg milk. The daily intakes of silage DM were not significantly different on the three silage treatments, and averaged 10.7, 11.0 and 11.0 kg per cow on the formic acid and the 2.0 and 44 1 t−1 formalin‐acid treatments respectively. The mean daily yields of milk were 15.1, 13.3 and 13.7 kg per cow in the unsupplemented treatments, and 18.2, 18.1 and 18.0 kg per cow in the supplemented treatments on the formic acid and the 2.0 and 44 1 t−1 formalin‐acid treatments respectively.On the basis of total animal production expressed in terms of metabolizable energy requirements, it was concluded that the differences between the three silages were small.

The effect of method of treatment with petroleum ether on the drying rate of grass leaves measured in the laboratory

AbstractExcised S24 perennial ryegrass leaves were dried in controlled and measured conditions of temperature (28°C), relative humidity (22%) and airspeed (40 cm s−1), without treatment or after treatment with petroleum ether (4O–60°C boiling point) applied in various ways. Subsequent increase in the drying rate of the leaves varied greatly with method of application of petroleum ether, and the results indicate that the modification of the waxes on the leaf surfaces, which results in reduced cuticular resistance to water loss, requires the presence of liquid petroleum ether on the leaf surface. This effect increases with temperature, and the increase is due to the enhanced activity of the petroleum ether in dissolving waxes, rather than to direct thermal effect on tissue resistance. The practical implications of employing such a technique are discussed.

Silage and milk production: a comparison between four rates of groundnut cake supplementation of silage of high digestibility

AbstractGrass silage made in late May from S24 perennial ryegrass was offered to twelve Ayrshire cows in a 16‐week feeding experiment. The silage had a DM content of 25.3%, a pH of 3.91, and contained 16.8% CP and 68.4% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with a cube offered at rates of 0.8, 1.4 and 2.0 kg per 10 kg milk. The cube contained 82.2% groundnut, plus molasses and minerals, and had 37.9% CP in the DM. The daily intake of silage DM was 11.4 kg per cow on average over the four treatments which did not differ significantly. The mean daily milk yields were 14.8 kg per cow in the control treatment, and 16.5, 18.2 and 18.4 kg in the 0.8, 1.4 and 2.0 kg supplement treatments respectively. The SNF, CP and lactose contents of the milk were Wghest on the 1.4 kg supplement treatment. It is concluded that with a high digestibility silage, there is little evidence to support the feeding of more than 1.4 kg of high‐protein cubes per 10 kg milk in the declining phase of lactation.

Silage and milk production. A comparision between barley and groundnut cake as supplements to silage of high digestibility

AbstractGrass silage of hjgh digestibility made in late May from S23 perennial ryegrass was offered to twelve Ayrshire cows in a 16‐week winter‐feeding experiment. The silage had a DM content of 27.2% and contained 147% crude protein and 70.3% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with barley, groundnut cake or a mixture of barley and groundnut supplying 4.7, 1.5 and 4.7 kg DM per cow per day respectively. The daily intakes of silage DM were 10.8 kg per cow in the control treatment and 8.6, 11.1 and 9.3 kg per cow in the barley, groundnut and barley plus groundnut treatments, respectively. The daily yields of milk were 14.6 kg per cow in the control, and 16.1, 17.6 and 17.9 kg per cow in the three supplement treatments, respectively. The fat content of the milk was highest in the barley treatment, whereas the SNF and CP contents were highest in the barley plus groundnut treatment. It is concluded that with a high digestibility silage, a supplement of groundnut cake was superior to barley for milk production.

The effect of physical form of a silage on its voluntary consumption and digestibility by sheep

AbstractSix castrated male sheep were used in a two‐period crossover experiment to investigate the effect of mincing on the voluntary intake and digestibility of a silage. The silage was a high‐quality material, containing 68 % digestihle organic matter in the dry matter, prepared from S24 perennial ryegrass cut with a precision chop forage harvester and ensiled with the addition of 2.3 1 t−1 formic acid as preser vative. The median size of particles in the unprocessed silage was 10–20 mm and in the minced silage 2–3 mm.The intakes of dry matter, organic matter and nitrogen for the minced silage were greater than for the unminced material, and for dry matter and organic matter intakes the differences were signi ficant (P<0.01). Mincing was associated, however, with a depression in the digestibility of all three constituents which offset the increase in intake. The intakes of digestible organic matter were 817 g d‐1 for the minced silage and 729 g d−1 for the unminced material (P>0.05). Corresponding figures for digestible nitrogen intakes were 208 gd−1and23.0 gd−1 (P>005).It is concluded that with high‐quality silage diets there is a physical component in the mechanism for the control of voluntary food intake. It is suggested that for sheep, depressions in the digestibility of dietary constituents are unlikely to occur until silages are chopped to a median particle size of 5–10 mm.

The effect of a short‐persistence systemic insecticide on the yield of perennial ryegrass

AbstractThe insecticide dimethoate was applied to a sward of S23 perennial ryegrass over a period of 2 years at three dose rates and at five frequencies of application. Annual DM yield was increased by up to 5% in the first year and by up to 17% in the second. The value of the additional yield is compared with the cost of obtaining it.

THE CONSUMPTION OF PERENNIAL RYEGRASS AND RED CLOVER BY GRAZING LAMBS

ABSTRACTGroups of six‐month old lambs, which were either experienced or inexperienced grazers, strip‐grazed swards of S24 perennial ryegrass or Hungaropoly tetraploid red clover, at daily herbage allowances of 20 or 40 g OM/kg LW, in late August and September. The swards were similar in N content, but the weight of standing crop, and its digestibility, were higher on grass than on clover. Estimates of herbage intake were made in two successive periods of 19 days. Intake (g OM/kg LW) was lower at low than at high allowance (by 22% and 28% in periods I and II). and experienced grazers ate more than inexperienced animals (by 27% and 22%). Intakes on clover were 28% higher than on grass in Period I, but in Period II the difference was not significant.