Effects of pasture type on the growth and wool production of weaner sheep during summer and autumn

1984 ◽  
Vol 24 (126) ◽  
pp. 322 ◽  
Author(s):  
PT Kenny ◽  
KFM Reed
Keyword(s):  
White Clover ◽  
Crude Protein ◽  
Perennial Grass ◽  
Red Clover ◽  
Subterranean Clover ◽  
Sheep Grazing ◽  
Neutral Detergent Fibre ◽  
Dry Matter Digestibility ◽  
Feeding Value ◽  
Persian Clover

The productivity of weaner sheep grazing lucerne, white clover, red clover or Persian clover and pastures sown with subterranean clover and perennial ryegrass, cocksfoot or tall fescue, was measured in summer-autumn trials incorporating four soil types in each of three years. During summer and autumn, the mean growth rate of sheep grazing lucerne, white clover or Persian clover pastures was 50 g/d compared with 1 g/d for sheep grazing perennial grass-subterranean clover pastures. Sheep grazing strawberry clover on reclaimed swampland, and sheep in a feedlot (fed hay and lupin grain) averaged 100 and 75 g/d, respectively. Sheep grazing red clover averaged 45 g/d over years 1 and 2. In year 2, a subterranean clover-dominant pasture was included in the study. Its feeding value was similar to that of the perennial grass-subterranean clover pastures. Sheep grazing legume pastures, and sheep in the feedlot, consistently produced more wool (up to 700 g/head) than sheep grazing the perennial grass-subterranean clover pastures. The concentration of neutral detergent fibre in herbage from legume pastures was frequently lower (P< 0.05) and the concentration of crude protein was frequently higher (P< 0.05) than in herbage from grass pastures. The dry matter digestibility of legume herbage was higher (P<0. 05) than that of grass herbage on only one occasion. Measurements of crude protein and neutral detergent fibre of pasture in December accounted for 67% of the variation in liveweight gain (P<0.01). Ewe weaners grazing red clover pasture exhibited an increase (P< 0.05) in teat length of 3.9 mm in 21d of grazing. Oestrous activity of ewe weaners was related to liveweight gain (r = 0.77). The implications of the results for agricultural systems are discussed.

Degradability of crude protein from clover herbages used in irrigated dairy production systems in northern Victoria

2001 ◽  
Vol 52 (3) ◽  
pp. 415 ◽  
Author(s):  
D. C. Cohen
Keyword(s):  
Protein Content ◽  
White Clover ◽  
Crude Protein ◽  
Nutritive Value ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Crude Protein Content ◽  
Persian Clover ◽  
Protein Supply ◽  
In Sacco

An in sacco (nylon bag) technique was used to estimate the degradability of dry matter (DM) and crude protein, and to estimate the effective rumen degradability of protein (ERDP), for 3 irrigated clover herbages. Pasture characteristics (nutritive values and leaf: stem ratios) were also described, and relationships to ERDP established. The nutritive value characteristics and degradabilities of white clover (Trifolium repens L.), Persian clover (Trifolium resupinatum L.), and subterranean clover (Trifolium subterraneum L.) were also compared for various regrowth periods (of 3, 4, 6, and 12 weeks). Nutritive value characteristics of clover herbages varied from 9.9 to 11.9 MJ/kg DM for metabolisable energy, 153 to 304 g/kg DM for crude protein, and 209 to 377 g/kg DM for neutral detergent fibre. The leaf: stem ratio correlated well with the crude protein content of the clovers, with herbages consisting of more leaf generally having superior crude protein content (R2 = 0.64, P < 0.001). The effective rumen degradability of protein for clover herbages ranged from 60 g/kg DM for mature (12 week regrowth) subterranean clover to 195 g/kg DM for vegetative (3 weeks regrowth) Persian clover. For clover herbages with a 3-week regrowth period, after initial cutting to 5 cm, and at ruminal outflow rates of 0.08/h, the effective rumen degradability of protein varied from 136 to 195 g/kg DM. A positive relationship between crude protein and ERDP (R2 = 0.82) suggested that ERDP could be estimated for clover herbages that have been previously assessed for crude protein content, obviating the need for in sacco studies. Calculated degradabilities were lower for all clovers when higher ruminal outflow rates were assumed. Using the metabolisable protein system, metabolisable protein supply and metabolisable protein in excess of animal requirements were calculated. Ruminal losses of nitrogen were also estimated for cows consuming white clover of varying regrowth periods in both early and late lactation. It was concluded that metabolisable protein supply is unlikely to limit production in these examples. At regrowth periods of 3 weeks, metabolisable protein contributions from microbial and dietary sources were similar, and twice that required by the animal. Ruminal losses of nitrogen were substantial and amounted to 66—23% of nitrogen intake. In the experiments reported here, if all of the energy required to excrete excess protein (as urea) could instead be used for the production of milk, cows may have produced 0.5mp;mdash;2.0 kg more milk per day. Such losses could potentially be reduced if the protein content and/or degradabilities of clover herbages were reduced, and/or energy rich supplements were offered.

Nutritive characteristics of annual species in irrigated pasture in northern Victoria

2006 ◽  
Vol 46 (8) ◽  
pp. 1015 ◽  
Author(s):  
J. W. Heard ◽  
S. A. Francis ◽  
P. T. Doyle
Keyword(s):  
Crude Protein ◽  
Nutrient Concentration ◽  
Subterranean Clover ◽  
Ground Level ◽  
Sampling Period ◽  
Neutral Detergent Fibre ◽  
Persian Clover ◽  
Rate Of Decline ◽  
Linear Decline ◽  
Selection Differentials

We examined changes in estimated metabolisable energy (ME), crude protein (CP) and neutral detergent fibre (NDF) concentrations of irrigated annual pastures through winter and spring in 2002. The types of pastures sampled were ‘high’ subterranean clover (HS, at least 800 g/kg DM clover), ‘low’ subterranean clover (LS, about 400 g/kg DM clover) and ‘low’ Persian clover (LP, about 500 g/kg DM clover). Estimates were also made of selection differentials, namely the nutrient concentration in the pasture fraction likely to be consumed expressed as a proportion of the nutrient concentration in the whole sward to ground level. The ME concentrations in all pasture types increased from May to August, after which concentrations in LS and LP declined, while the ME concentrations in HS declined after September. Low Persian pasture was significantly (P<0.001) higher in ME than the subterranean clover pastures except in September. There was a significant quadratic relationship between ME and time in months and this relationship differed significantly between the 3 pasture treatments. There was a significant (P<0.001) linear decline in CP concentration through the sampling period. The rate of decline in CP concentration was greatest for HS and lowest for LP pastures. Neutral detergent fibre concentrations declined gradually until August and then increased in all pastures. High subterranean clover pastures were lower (P<0.05) than LS pastures in all months. Low Persian clover pastures were higher in NDF than HS pastures, but lower than LS pastures in most months.There were small but significant differences in selection differentials for estimated ME between months when pastures were cut to 4 cm. Selection differentials for ME were between 1.01 and 1.13 across pasture types. Crude protein selection differentials were higher than for ME and varied between 1.11 and 1.46. There were small significant differences in selection differentials between months for NDF (0.74–0.96). Calculated selection differentials at different cut heights indicated that a nutrient gradient existed throughout the annual pasture sward. Pastures cut at high (>8 cm) cut heights had higher ME and CP and lower NDF, than pastures cut to 4 cm. Differences in selection differentials at different cut heights were apparent between pasture types.

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

2005 ◽  
Vol 45 (12) ◽  
pp. 1577 ◽  
Author(s):  
K. B. Kelly ◽  
C .R. Stockdale ◽  
W. K. Mason
Keyword(s):  
Leaf Area ◽  
White Clover ◽  
Growth Rates ◽  
Carbon Balance ◽  
Red Clover ◽  
Subterranean Clover ◽  
Net Photosynthesis ◽  
First Year ◽  
Second Year ◽  
Persian Clover

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.

Competition among seedlings of perennial grasses, subterranean clover, white clover, and annual ryegrass in replacement series mixtures

2000 ◽  
Vol 51 (3) ◽  
pp. 377 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
White Clover ◽  
Plant Competition ◽  
Perennial Grass ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Perennial Grasses ◽  
Maximum Likelihood Estimates ◽  
Annual Ryegrass ◽  
Replacement Series ◽  
Successful Establishment

Seedlings of 3 perennial grasses, Danthonia linkii Kunthcv. Bunderra, D. richardsonii Cashmore cv. Taranna(wallaby grasses), and Phalaris aquatica L. cv. Sirosa,were each grown in replacement series mixtures with seedlings ofTrifolium repens L. (white clover),Trifolium subterraneum L. var. brachycalycinum (Katzn.et Morley) Zorahy & Heller cv. Clare (subterraneanclover), and Lolium rigidum L. (annual ryegrass). Plantswere sown 5 cm apart in boxes (45 by 29 by 20 cm) at a density of 307plants/m2. Maximum likelihood estimates were usedto derive parameters of a non-linear competition model using the dry matterweights of perennial grasses and competitors at 3 harvests, approximately 168,216, and 271 days after sowing. Intra-plant competition was examined inmonocultures of each species, grown at plant spacings of 2, 5, and 8 cm apartwith plants harvested at the above times.Competition occurred in all perennial grass–competitor mixtures, exceptin those of each perennial grass with white clover and thephalaris–subterranean clover mixture (Harvest 1) and those withD. richardsonii and phalaris grown with white clover(Harvest 2). For D. richardsonii (Harvests 1 and 2) andD. linkii (Harvest 1 only) grown with white clover andthe phalaris–subterranean clover (Harvest 1), the two species in themixture were not competing. In the phalaris–white clover mixture, eachspecies was equally competitive (Harvests 1 and 2). These differences incompetition and aggressiveness reflected differences in individual plantweights in monocultures where there was an effect (P < 0.05) of species ondry matter weight per box, but no significant effect of plant spacing.These data indicated that for successful establishment,D. richardsonii and D. linkiishould not be sown in swards with either subterranean clover or white clover,or where populations of annual ryegrass seedlings are likely to be high.Phalaris was more compatible with both white clover and subterranean clover,but aggressively competed with by annual ryegrass.

The assessment of herbage legume varieties. II. In vitro digestibility, water soluble carbohydrate, crude protein and mineral content of primary growth of clover and lucerne

1966 ◽  
Vol 66 (3) ◽  
pp. 351-357 ◽  
Author(s):  
W. Ellis Davies ◽  
G. ap Griffith ◽  
A. Ellington
Keyword(s):  
White Clover ◽  
Crude Protein ◽  
Dry Matter ◽  
Red Clover ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
In Vitro Digestibility ◽  
Primary Growth

The primary growth of eight varieties of three species–white clover (3), red clover (4) and lucerne (1)–was sampled at fortnightly intervals and the percentage dry matter, in vitro digestibility, crude protein, water soluble carbohydrates, P, Ca, K, Na and Mg were determined.Differences between species were nearly always significant and the general order of merit was white clover, red clover and lucerne. The exceptions were for dry-matter percentage where this order was reversed, and red clover had the lowest Na and highest Mg content.

scholarly journals The search for alternative temperate perennial pasture species for low to medium rainfall environments in Tasmania

2016 ◽  
Vol 16 ◽  
pp. 275-279
Author(s):  
E.J. Hall ◽  
R. Reid ◽  
B. Clark ◽  
R. Dent
Keyword(s):  
Perennial Grass ◽  
Dactylis Glomerata ◽  
Red Clover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Sheep Grazing ◽  
Cool Temperate ◽  
Perennial Legume ◽  
Perennial Legumes ◽  
Pasture Plants

In response to the need to find better adapted and more persistent perennial pasture plants for the dryland pastures in the cool-temperate low to medium rainfall (500-700 mm) regions, over 1000 accessions representing 24 species of perennial legumes and 64 species of perennial grasses, were introduced, characterised and evaluated for production and persistence under sheep grazing at sites throughout Tasmania. The work has identified four alternative legume species in Talish Clover (Trifolium tumens). Caucasian Clover (T. ambiguum), Stoloniferous Red Clover (T. pratense var. stoloniferum), Lucerne x Yellow Lucerne Hybrid (Medicago sativa x M.sativa subsp. falcata); and two grass species in Coloured Brome (Bromus coloratus) and Hispanic Cocksfoot (Dactylis glomerata var hispanica). Keywords: persistence, perennial grass, perennial legume

scholarly journals 159 The effect of multispecies swards on parasite faecal egg counts of grazing lambs

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 170-170
Author(s):  
Romina A Rodriguez ◽  
Cornelia Grace ◽  
Mary B Lynch ◽  
Helen Sheridan ◽  
Stephen Lott ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Perennial Ryegrass ◽  
White Clover ◽  
Repeated Measures ◽  
Perennial Grass ◽  
Red Clover ◽  
The Other ◽  
Birdsfoot Trefoil ◽  
Faecal Egg Counts

Abstract Multispecies swards (MSS) for ruminants are increasing in popularity in temperate regions. The objective of this study was to evaluate the effect of MSS containing grasses, legumes and herbs on lambs faecal egg counts (FEC) compared to a perennial ryegrass monoculture. Over two years (2015 and 2016) lambs (n = 60 per year, n = 120 in total per treatment) grazed one of four sward types. The treatments were: perennial ryegrass only (PRG), perennial grass and white clover (PRGWC), six species sward (perennial ryegrass, timothy, plantain, chicory, white and red clover; 6S) and nine species (9S) additional to the 6S were cocksfoot, greater birdsfoot trefoil and yarrow. Feces samples were collected fortnightly commencing when lambs were six weeks old and FEC were determined by the modified McMaster procedure for quantifying Nematodirus and Trichostrongylus eggs. All lambs were treated with anthelmintic at 12 weeks of age and subsequent anthelmintic treatments were administered when a threshold of 400 egg per gram (epg) was reached. The statistical analysis used was a repeated measures model in PROC MIXED of SAS. Nematodirus FEC did not differ with treatment (P &gt; 0.05). Trichostrongylus FEC was influenced by sward type (P &lt; 0.05), the lambs grazing the PRG sward displaying higher FEC, while the lambs grazing the 9S sward displaying lower FEC compared to other treatments. The lambs offered PRG required fewer days in reach the 400 epg threshold compared to the other treatments (P &lt; 0.05) that did not differ. The repeatability of FEC from one date to the next date was 21.54% and 11.85% for Nematodirus and Trichostrongylus respectively, being considered low. The correlation between FEC (Nematodirus) and ADG (weaning-slaughter) was positive (0.1377), but FEC (Trichostrongylus) and ADG correlation was negative (-0.1084). These results suggest that lambs offered the 9S treatment had lower FEC of Trichostrongylus eggs compared to PRG.

Dry matter intake, nutrient selection and milk production of dairy cows grazing rainfed perennial pastures at different herbage allowances in spring

1999 ◽  
Vol 39 (8) ◽  
pp. 923 ◽  
Author(s):  
P. J. Moate ◽  
D. E. Dalley ◽  
J. R. Roche ◽  
C. Grainger
Keyword(s):  
Dairy Cows ◽  
Milk Production ◽  
Crude Protein ◽  
Dry Matter ◽  
Dry Matter Intake ◽  
Neutral Detergent Fibre ◽  
Dry Matter Digestibility ◽  
Herbage Intake ◽  
Selection Differentials

Summary. The effect of herbage allowance (20, 30, 40, 50, 60 and 70 kg DM/cow. day) on the consumption of nutrients from herbage and milk production by cows in early lactation, was examined. The experiment was conducted on rainfed perennial ryegrass pastures in September and October 1997 in south-eastern Victoria, Australia. The herbage on offer comprised 64% perennial ryegrass, 21% other grasses, 1% white clover, 5% weeds and 9% dead material on a dry matter (DM) basis. The average pregrazing herbage height was 13 cm, at an estimated pregrazing herbage mass of 3.6 t DM/ha. The herbage on offer was of high quality containing 11.6 MJ metabolisable energy/kg DM, 202 g crude protein/kg DM and 525 g neutral detergent fibre/kg DM. Concentrations of calcium, magnesium, sodium, potassium, phosphorus, sulfur and chloride were 4.4, 2.2, 4.4, 31.2, 3.5, 2.7 and 11.4 g/kg DM, respectively. As daily herbage allowance per cow increased, dry matter intake increased curvilinearly (P<0.01) from 11.2 to 18.7 kg DM/cow. day. This was associated with a decrease in utilisation of herbage from 54 to 26% and an increase in milk production from 25.9 to 29.1 kg/cow. day. The cows on all treatments grazed for less than 8.7 h/day. The increase in intake was achieved by an increase in the rate of herbage intake from 1.5 to 2.2 kg DM/h for herbage allowances of 20 and 70 kg/cow.day, respectively. Irrespective of herbage allowance, cows selected a diet that was approximately 10% higher in in vitro dry matter digestibility and 30% higher in crude protein than that in the herbage on offer. The neutral detergent fibre content of the herbage selected was lower (P<0.05) than that on offer. The herbage consumed contained more (P<0.05) magnesium, potassium and sulfur, the same amount of calcium and phosphorus and less (P<0.05) sodium and chloride than the herbage on offer. For rainfed perennial pastures in spring, herbage allowance is an important factor in determining voluntary feed intake and production of dairy cows. To achieve 30 L from herbage, without supplementation, high herbage allowances are required. The increase in herbage intake, with increasing herbage allowance, resulted from an increase in rate of dry matter intake and not an increase in grazing time. No relationship was evident between herbage allowance and the selection differentials for in vitro dry matter digestibility, crude protein and neutral detergent fibre. Selection differentials for rainfed perennial pastures in spring are similar to those reported for irrigated perennial pastures in northern Victoria in spring and autumn. When determining nutrient requirements it is important to consider the interaction between herbage intake and nutrient concentration in the herbage.

Effects of pH and aluminium on the growth of temperate pasture species. II. Growth and nodulation of legumes

1991 ◽  
Vol 42 (5) ◽  
pp. 893 ◽  
Author(s):  
DC Edmeades ◽  
FPC Blamey ◽  
CJ Asher ◽  
DG Edwards
Keyword(s):  
White Clover ◽  
Trifolium Pratense ◽  
Inorganic Nitrogen ◽  
Red Clover ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Lotus Corniculatus ◽  
Culture Solution ◽  
Solution Ph ◽  
Lotus Pedunculatus

Ten temperate pasture legumes inoculated with appropriate rhizobia were grown for 31 days in flowing solution culture. Solution ionic strength was approximately 2700 8M and contained inorganic nitrogen (150 , 8M NO3-) only at the commencement of the experiment. Solution pH was maintained at 4.5, 5.0, 5.5 and 6.0. Also, five aluminium (Al) treatments were imposed, with nominal Al concentrations of 0, 3, 6, 12 and 24 8M (2.5, 7.1, 8.3, 11.2 and 24.7 8M Al measured) at pH 4.5. Solution pH <6 . 0 markedly reduced total dry mass (TDM) in all cultivars of white clover (Trifolium repens) cvv. 'Grasslands Pitau, Huia, G18 and Tahora' and red clover (Trifolium pratense) cvv. 'Grassland Turoa and Pawera', and to a lesser extent in the two subterranean clover (Trifolium subterraneum) cvv. 'Tallarook and Woogenellup'. In contrast, solution pH had no effect on the growth of Lotus corniculatus cv. Maitland, while Lotus pedunculatus cv. Maku grew best at pH 4.5. Lotus pedunculatus cv. Maku grew best in solution where the sum of the activities of the monomeric Al species {Alm} was maintained at 5.9 8M. The growth of all other species was decreased with Al in solution, a 50% reduction in TDM being associated with c. 6 8M {Alm] for white clover and subterranean clover, and c. 3 8M in red clover and Lotus corniculatus cv. Maitland.

Effects of season and time since defoliation on the nutritive characteristics of three irrigated perennial pasture species in northern Victoria 1. Energy, protein and fibre

1999 ◽  
Vol 39 (5) ◽  
pp. 555 ◽  
Author(s):  
C. R. Stockdale
Keyword(s):  
Perennial Ryegrass ◽  
White Clover ◽  
Crude Protein ◽  
Energy Content ◽  
Energy Concentration ◽  
Neutral Detergent Fibre ◽  
Plant Parts ◽  
Metabolisable Energy ◽  
Grazing Dairy Cows

The study reported here compared the nutritive characteristics of the 3 most common irrigated perennial pasture species grown in northern Victoria as they regrew after defoliation at various times during the year. In addition, the relative influence of changes to the proportions of morphological components and the nutritive characteristics of the individual components on the quality of whole plants was examined. The nutritive characteristics of white clover (Trifolium repens cv. Haifa), ryegrass (Lolium perenne cv. Ellet) and paspalum (Paspalum dilatatum) were examined at weekly intervals on 4 occasions during spring–autumn, 1993–94. On each occasion, pastures were defoliated with a drum mower and allowed to regrow for up to 9 weeks; defoliation dates were 24 September, 26 November, 28 January and 25 March. The variation in estimated metabolisable energy [obtained from in vitro dry matter (DM) digestibility], crude protein and detergent fibre concentrations within species was significantly (P<0.01) less than between clover and the grasses. White clover was consistently high in metabolisable energy (9.3–11.2 MJ/kg DM) and crude protein (17.7–27.7% DM), and low in neutral detergent fibre (27.8–39.8% DM) in all periods. At the other extreme, paspalum had a metabolisable energy content that peaked at 9.3 MJ/kg DM, and fell as low as 7.4 MJ/kg DM. Paspalum also had low protein (7.5–14.7% DM) and very high neutral detergent fibre (61.9–69.9% DM) concentrations. Ryegrass varied greatly in metabolisable energy concentration between the 4 periods, being high in autumn (average of 10.2 MJ/kg DM) and low in summer–autumn (average of 8.4 MJ/kg DM). Metabolisable energy apart, there were few differences in the crude protein and detergent fibre contents of ryegrass and paspalum. Perennial ryegrass is generally considered a superior feed to paspalum, but the data indicate this is not always the case under irrigation in northern Victoria. The nutritive characteristics of the plant fractions (leaf, stem, dead, inflorescence) were analysed separately to give an indication of the limits to selection by grazing cows. Differences in metabolisable energy between leaf and stem in both white clover and perennial ryegrass suggested that grazing dairy cows could consume a pasture diet which is likely to be slightly higher in energy than that in the herbage on offer. With paspalum, this is unlikely to be the case because differences in energy content between plant parts were small. However, with all species, cows should be able to consume herbage that is significantly higher in protein, and lower in detergent fibre, than that on offer because of differences in their concentrations in leaf and stem. The nutritive characteristics of morphological components of each species remained relatively constant throughout the study. Therefore, it would seem that it is the proportions of these fractions in the plant, together with severity of grazing, that will largely determine the degree of selection that can occur.

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