Annual Ryegrass Pasture Research Articles

The performance of Mediterranean dairy sheep given access to sulla ( Hedysarum coronarium L.) and annual ryegrass ( Lolium rigidum Gaudin) pastures in different time proportions

Three experiments were carried out to assess the feeding value of sulla ( Hedysarum coronarium L.) as complementary grazing source for Sarda dairy sheep basically fed on annual ryegrass ( Lolium rigidum Gaudin) pasture. In experiment 1 (E1), non-pregnant (D) and pregnant (P) ewes were allotted into three groups allocated for 9 h daily, respectively, on plots of sulla (S9), annual ryegrass (R9) or sulla for 3 h in the morning and annual ryegrass for the remaining time (S3R6). In experiment 2 (E2), the treatments were sulla (S22), ryegrass (R22) and two “time mixtures” consisting, respectively, of 3 (S3R19) or 6 h allocation on sulla (S6R16). In experiment 3 (E3) only R22 and S6R16 were compared. In both E2 and E3, milked ewes were used and the total time on the plots was 22 h daily. In E1, the total digestible herbage intake (DDMI), measured by the n-alkane method, was affected by the interaction between sheep physiological state and grazing system ( P<0.01). No effect of the above factors on sheep body weight and body condition changes was evident. In E2, DDMI did not differ between groups up to May when S22 and S3R19 outperformed R22, S6R16 behaving as intermediate ( P<0.05). Milk yield paralleled DDMI results. Milk composition was unaffected, except for milk urea ( P<0.001), lower in R22 (34.0 mg/dl) than the other groups (39.6 mg/dl, S3R19; 44.4 mg/dl, S6R16; 44.3 mg/dl, S22). In E3, S6R16 ewes grazed for less than 50% of the allocation time on sulla. To conclude, S3R19 can partially offset the decay of grass nutritive value in spring but results are intermediate between those of the mono-specific pastures. S6R16 is less beneficial than S3R19 possibly due to the detrimental effect of condensed tannins on grazing behaviour.

Effect of early weaning on the performance of three-year-old, first-calf beef heifers and calves reared in the subtropics.

The objective of this study was to investigate the effectiveness of early weaning fall-born calves on heifer and calf performance in Florida. Over two consecutive years, 3-yr-old Braford and Brahman x Angus first-calf heifers were assigned randomly to one of two treatments; early-weaned (EW, n = 20 and 30 for yr 1 and 2, respectively) and normal-weaned (NW, n = 20 and 38 for yr 1 and 2, respectively). Calves were EW on January 23 and 3 for yr 1 and 2, respectively. Following EW, all first-calf heifers were returned to bahiagrass (Paspalum notatum) pastures with the mature cowherd. Early-weaned calves were maintained on annual ryegrass (Lolium multiflorum) pastures at 8.2 and 10.7 calves/ha for yr 1 and 2, respectively, and were provided supplemental grain mixture (14% CP) at 1.0% of BW daily. Normal-weaned calves remained with their dams in the mature cowherd on bahiagrass. Final calf BW was collected on April 17 (d 84) and April 24 (d 111) for yr 1 and 2, respectively. Early-weaned calves had a greater (P < 0.001) ADG (0.17 kg/d) in yr 1, but a lower (P < 0.001) ADG (-0.24 kg/d) in yr 2 compared with NW calves. Early weaning resulted in heavier first-calf heifers with greater BCS at the time of normal weaning (August 1; 491 vs. 452 kg, with BCS = 6.34 vs. 4.75 for EW and NW heifers, respectively; SEM = 5.0 and 0.07). Heifers with EW calves had a higher (P < 0.07) pregnancy rate during both years than normal-weaned heifers (89.5 vs. 50.0 and 96.7 vs. 80.0% pregnant during yr 1 and 2, respectively). Early-weaned, first-calf heifers also had a lower (P < 0.05) calving interval in yr 2 (384 vs. 404 d; SEM = 6.0). These data suggest that EW will improve body condition of first-calf heifers resulting in an increased pregnancy rate. Early-weaned calves maintained on winter ryegrass provide producers with the ability to optimize early-weaned calf performance, while capitalizing on low cost of gain and favorable spring markets.

Influence of agricultural land management on organic matter content, microbial activity and aggregate stability in the profiles of two Oxisols

The effects of agricultural land use on organic matter content and related soil microbial and physical properties were compared with those under undisturbed native grassland in KwaZulu-Natal, South Africa. Two separate farms situated on Oxisols were used and both contained fields with continuous long-term (>20 y) cropping histories. At site 1, soil organic C content in the surface 30 cm followed the order permanent kikuyu pasture > annual ryegrass pasture > native grassland > sugarcane > maize under conventional tillage (CT). At site 2, organic C in the surface 30 cm decreased in the order kikuyu pasture > native grassland > annual ryegrass pasture > maize under zero tillage (ZT) > maize CT. Organic C, microbial biomass C, percentage organic C present as organic C, basal respiration and aggregate stability were substantially greater in the surface 5 cm under maize ZT than maize CT but this trend tended to be reversed in the 10- to 30-cm layer. In the undisturbed sites (e.g. native grassland and kikuyu pasture) the metabolic quotient increased with depth. By contrast, under maize CT and sugarcane there was no significant stratification of organic C, yet there was a sharp decrease in the metabolic quotient with depth. Aggregate stability was high under both native grassland and kikuyu pasture and it remained high to 40 cm depth under the deep-rooted kikuyu pasture. Although soil organic C content was similar under maize CT and sugarcane, values for microbial biomass C, percentage of organic present as microbial biomass, basal respiration and aggregate stability were lower, and those for metabolic quotient and bulk density were higher, under sugarcane. This was attributed to the fallow nature of the soil in the interrows of sugarcane fields. It was concluded that the loss of organic matter, microbial activity and aggregate stability is potentially problematic under maize CT, sugarcane and annual pasture and measures that improve organic matter status should be considered.

Effect of Protein Source and Soluble Carbohydrate Addition on Rumen Fermentation and Lactation Performance of Holstein Cows

Rumen in vitro and in vivo experiments were conducted to evaluate the effect of rumen undegradable protein and soluble carbohydrates on rumen ammonia N release and lactation performance of Holstein cows. In the in vitro experiment, freeze-dried annual ryegrass (Lolium multiflorum, LAM) pasture was supplemented 1:1 with ground corn-based grain supplements containing expeller or solvent soybean meal with sucrose or lactose supplements at 0, 2.5, or 5% of dry matter (DM). The ammonia release rate was slower with expeller compared with solvent soybean meal-supplemented diets. Sucrose supplementation at the 5% level lowered rumen ammonia concentrations, but lactose-fortification of grain supplements was without effect. In the in vivo study, 32 multiparous Holstein cows were blocked according to milk yield and randomly assigned to corn-based grain supplements containing 1) solvent soybean meal, 2) solvent soybean meal + 5% sucrose supplement, 3) expeller soybean meal, or 4) expeller soybean meal + 5% sucrose supplement. Grain supplements and fresh annual ryegrass were component fed at approximately a 1:1 grain to forage ratio (DM basis). Forage DM intake was higher for cows receiving solvent soybean meal supplemented grain supplements than those receiving expeller soybean meal (12.2±2.1 vs. 11.4±2.2 kg/d), but total DM intake was similar for all diets (22.8±2.9 kg/d). Fat-corrected milk yield was similar for all diets averaging 37.5, 38.2, 39.1, and 37.6 kg/d for diets 1 to 4, respectively. Rumen fermentation, milk urea nitrogen, and body condition were unaffected by supplements; however, cows fed grain supplement 1 utilized dietary energy more efficiently than cows offered the other dietary treatments. High dietary crude protein concentrations may have limited lactation response to rumen undegradable protein and sugar.

Nitrate leaching under phalaris, cocksfoot, and annual ryegrass pastures and implications for soil acidification

Nitrogen uptake and nitrate (NO-3) leaching below 1.1 m was estimated under phalaris, cocksfoot, and annual ryegrass pastures and under bare fallow in a 4-year field experiment under control and high N (500 kg N/ha) treatments in north-eastern Victoria (693 mm/year rainfall for the study period). The perennial grasses, particularly phalaris, took up more N in herbage than annual ryegrass. High concentrations of NO3-N were measured at 1 m depth below all treatments, suggesting that NO3- losses from pastures have potential to contaminate streams and/or groundwater. Perennial pastures were only able to reduce NO3- leaching compared with annuals in drier than average years. Values calculated for acid addition due to NO3-leaching resulted in a net annual input of approximately 1 kmol H +/ha.year under the phalaris pasture compared with 2 kmol H +/ha.year under annual ryegrass. Adding these figures to carbon cycle addition data of 1 kmol H+/ha.year (measured in a previous study) corresponds to a lime rate of 100 and 150 kg lime/ha.year being required to stop further acidification under these pasture types. A 1 unit pH decline to 30 cm depth was estimated to take 42 years under annual pasture or 67 years under perennial grasses. Whilst perennial pastures have a role in reducing soil acidification, lime application is the most important management option in balancing soil acidification caused by agriculture.

Annual Ryegrass Stored as Balage, Haylage, or Hay for Lactating Dairy Cows

Frequent rainfall in south Louisiana often limits the successful harvest of annual ryegrass (Lolium multiflorum L.) as high quality hay. A 2-yr study was conducted to determine the effect of conserving ryegrass as balage on ensiling efficiency, storage losses, and feeding value. Ryegrass conservation treatments were balage (BLG), haylage (HLG, positive control), and hay (HAY, negative control). Ryegrass was cut at the boot stage and, following a 48-h wilt, was baled and wrapped with stretch film (BLG) or was chopped and stored in a bag silo (HLG), HAY (bloom stage) was harvested approximately 3 wk later when weather permitted and was stored indoors. At the conclusion of the 6-mo storage period, the nutritional value of stored forages was assessed with lactating Holstein cows (n = 21). Ryegrass pH values were lower, and lactate concentrations were slightly higher for HLG than BLG. Storage losses averaged 8.9% of dry matter (DM) for BLG compared with 3.7% for barn-stored HAY. Forage nutritive value was similar between ensiled forages; however, HAY was lower in protein and energy than other treatments. Cows fed HLG consumed 17.3% more forage DM and tended to produce more fat-corrected milk (FCM) than cows fed BLG. Feed efficiency (Ib FCM/Ib dry matter intake [DMI]) was higher for the BLG treatment than HAY. No treatment differences were observed for milk composition or cow weight/condition changes, Balage is an acceptable means of storing high quality ryegrass forage.

Water use and drainage under phalaris, cocksfoot, and annual ryegrass pastures

The water balance equation was used to calculate plant water use and drainage below a depth of 1·1 m for phalaris, cocksfoot, and annual ryegrass pastures and bare fallow at Rutherglen in north-eastern Victoria. Rainfall from 1990 to 1993 averaged 693 mm/year. Soil water use was greater under perennials over the summer{autumn period and the soil profile was approximately 50 mm drier at the beginning of each drainage season. Following autumn rains, soil water profiles under all treatments converged, usually reaching similar water contents within 4{6 weeks. Over 4 years, soil under phalaris became 33 mm drier, and cocksfoot 24 mm drier (P &lt; 0· 001), than under annual ryegrass or bare fallow. Phalaris had higher actual evapotranspiration (P &lt; 0·05; average, 642 mm/year) than cocksfoot (619 mm/year) and annual ryegrass (606 mm/year), the latter two not differing significantly. Drainage occurred during winter and early spring, ranging from 2 to 12 mm in 1991 (515 mm rainfall) to &gt;100 mm/year in 1990 and 1992 (671 mm and 901 mm rainfall, respectively). The variation between years was greater than the differences between pastures in any one year. Averaged over the 4 years, drainage losses below 1 .1 m decreased in the order bare fallow &gt; annual ryegrass &gt; cocksfoot &gt; phalaris, although differences between the 3 pasture types were not statistically significant. Drainage under phalaris and cocksfoot may have been overestimated relative to annual ryegrass and fallow because of subsurface flow, at the top of the B horizon, between the wetter and drier plots. The drainage under phalaris may also have been overestimated because this pasture extracted water below the depth of soil water measurement. Allowing for these effects, the estimated drainage under phalaris may have been 49-56 mm/year compared with 80-87 mm/year under annual ryegrass, an overall reduction of more than one-third. Although perennial pasture grasses are unlikely to stop all recharge to groundwater in high rainfall areas (&gt;600 mm/year) of south-eastern Australia, they offer a practical way to combine profitable agriculture with reduced land degradation.

Consumer Acceptability and p‐Carotene Content of Beef as Related to Cattle Finishing Diets

ABSTRACTRibeye steaks (Longissimus muscle) and ground beef from 15 Angus or Angus × Hereford steers slaughtered at weights of 480–500 kg were evaluated for proximate composition, color, β‐carotene content and consumer preference. Three groups of five animals were finished on annual ryegrass pasture (Lolium multiflorum), ryegrass and ‘Coastal’ bermu‐dagrass hay (Cynodon hybrid), or a feedlot diet.β‐carotene content of ribeye steaks and ground beef was higher (p &lt; 0.05) for the forage finished animals than those finished in the feedlot. There was no difference in scores from consumer panels (n = 80) for steaks from feedlot or pasture finished animals, but scores for ground beef from cattle finished on the feedlot diet were higher than other treatments (p &lt; 0.05).

Prepartum body condition and weight influences on reproductive performance of first-calf beef cows

Data were collected on 476 spring-calving, primiparous cows at six locations in Louisiana over a 2-yr period. Objectives of the study were to evaluate changes in prepartum body condition score (BCS) and BW of heifers when fed varying energy levels and to determine the influences of prepartum BCS and BW changes and BCS at calving on postpartum traits. Heifers were allocated to one of three energy levels from approximately 90 d prepartum to parturition. The diets were formulated to provide low, recommended, and high energy levels based on TDN requirements. After calving, cows were placed on annual ryegrass pasture and managed similarly at each location. Weight and BCS at calving were greater (P < .05) for females with higher BCS at 90 d prepartum (IBCS) and for those assigned to higher energy levels. Calving and calf growth traits were not affected (P > .05) by IBCS, energy level, prepartum changes in BCS and BW, or BCS at calving. Prepartum changes in BCS and BW regulated by varying energy levels had no effect (P > .05) on postpartum reproduction; however, BCS at calving influenced (P < .03) pregnancy rate and days to pregnancy. Cows with BCS 6 and 7 at calving had higher (P < .05) pregnancy rates (87.0 and 90.7%) than those with BCS 4 and 5 (64.9 and 71.4%). Interval to pregnancy for cows with BCS 4 at calving was 10 to 18 d longer (P < .05) than for those with BCS > or = 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Early venison production from red deer (Cervus elaphus) as affected by grazing perennial or annual ryegrass pastures, pasture surface height and immunization against melatonin

SUMMARYTwo grazing experiments in New Zealand, using newly weaned red deer stags, assessed methods of maximizing growth over winter and spring, with the objective of attaining a slaughter weight of 92 kg liveweight (&gt; 50 kg carcass) at the end of spring, by 12 months of age. Perennial ryegrass/white clover pastures, and the same direct-drilled with an annual ryegrass, were grazed at two surface heights (5 cm and 10 cm; Experiment 1; 1988) or at similar pasture mass (Experiment 2; 1989). Balanced groups of stags grazing each forage were immunized against melatonin, commencing at 3 months of age (Expt 1) or at birth (Expt 2). Moata annual ryegrass comprised 19–46% of the feed on offer in Expt 1 and 65–82% in Expt 2. Perennial ryegrass comprised 79–89% of control pastures and white clover generally comprised &lt; 10% of all pastures. Organic matter digestibility of both the feed on offer and diet selected, determined with deer fistulated in the rumen or oesophagus, was 75–80%.In Expt 1, rates of body growth during winter were greater for stags grazing at 10 cm than at 5 cm pasture height, with no effect due to the inclusion of annual ryegrass. During spring, growth rates were similar for stags grazing 10 cm pastures and the 5 cm pasture containing annual ryegrass, but were lower on 5 cm pasture based on perennial ryegrass. Inclusion of annual ryegrass slightly increased winter rates of herbage dry matter accumulation, animal carrying capacity and the proportion of stags attaining target slaughter weight.In Expt 2, annual ryegrass pastures were of higher organic matter digestibility than perennial pastures during winter, and supported greater rates of liveweight gain (LWG) and voluntary feed intake (VFI) than the perennial ryegrass. During spring, LWG increased in both groups of stags although the difference between the two groups ceased to be significant. More of the animals grazing annual ryegrass pastures attained target slaughter weight than those grazing perennial pasture. Rumen acetate: propionate ratio, measured in fistulated stags, was similar for both groups of animals. Relative to perennial ryegrass, pastures containing high proportions of annual ryegrass resulted in similar animal carrying capacity during winter but substantially lower carrying capacity in spring.Antibodies binding melatonin were detected in 75% of immunized animals, with higher and more persistent titres being obtained using Freund's than using Dextran adjuvant and titre being much higher in stags immunized at birth than at 3 months of age. This was associated with a small and variable increase in plasma prolactin concentration, but had no effect upon plasma concentrations of LH or testosterone or upon LWG.It was concluded that the small increase in deer production attributable to annual ryegrass was mainly due to higher VFI, and that grazing perennial ryegrass/white clover pastures at 10 cm surface height resulted in higher levels of deer production than grazing at 5 cm surface height. These studies emphasise the feasibility of early venison production from grazed pastures in New Zealand, and show that the young deer were growing close to their genetic potential under this system.

Protein and fiber digestion by steers grazing winter annuals and supplemented with ruminal escape protein.

Six abomasally cannulated Hereford steers (12 mo of age, 300 +/- 10 kg) grazing annual ryegrass (Lolium multiflorum Lam.) paddocks were used in a replicated 3 x 3 Latin square design to determine effects of ruminal escape protein (EP) supplementation on forage intake, fiber digestion, and protein flow to the intestine. Steers were fed one of three isoenergetic supplements: high ruminal escape protein (HEP), low ruminal escape protein (LEP), or corn, which supplied an estimated .25, .125, or 0 kg of EP/d in addition to EP supplied by corn. Fish meal (FM) and distiller's dried grains with solubles (DDGS) were sources of EP; FM provided 66.7% and DDGS provided 33.3% of estimated EP. Steers were adjusted to each supplement for 7 d before a 4-d collection period. Both total and forage DMI responded quadratically (P less than .03 and P less than .07, respectively) to EP supplementation. Total tract DM digestion tended (P less than .13) to increase linearly with EP supplementation. Abomasal total CP flow increased linearly (P less than .10) as supplemental EP increased. Crude protein flow in steers receiving HEP, LEP, and corn was 1,137, 1,027, and 844 g/d, respectively. Likewise, abomasal nonammonia N (NAN) tended to be greater (P less than .15, linear) for steers receiving HEP. Nonammonia N flows were 1,044, 955, and 771 g/d for steers receiving HEP, LEP, and corn, respectively. Abomasal ammonia flow did not differ (P less than .20) among treatments, nor did reticuloruminal fiber digestion (P less than .20). These data indicate that EP can increase postruminal protein flow and will not negatively affect fiber digestion in steers grazing annual ryegrass pastures.

Water-efficient clover fixes soil nitrogen, provides winter forage crop

The high yield and excellent protein content of ‘Multicut’ berseem clover make it a useful winter forage and cover crop option on Valley and foothill land where supplemental irrigation is available. This variety is a winter-and-spring annual that produces five or six cuttings from January to June if planted in October. Timing of the winter harvests is weather-dependent. Water use by berseem is about the same as for annual ryegrass pasture or oats grown for hay. Variety and nitrogen-fixation trials have been conducted at Davis since 1983. The help of Richard Caldwell, Lawrence Larsen, R. S. Loomis, Helena Marques, Dan Pantone, and Richard Snyder is gratefully acknowledged. Cultural practice recommendations for berseem clover were reported in California Agriculture in September 1987. Some of the nitrogen fixation data were published previously in the Journal of Agronomy and Crop Science 264:202–207, 2990.

Structure of the corynetoxins, metabolites of Corynebacterium rathayi responsible for toxicity of annual ryegrass (Lolium rigidum) pastures

The corynetoxins, toxic metabolities of Corynebacterium rathayi formed in galled seed-heads of infected annual ryegrass, Lolium rigidum, are shown to be new members of the tunicamycin group of antibiotics. They consist of N-acetylglucosaminyl-tunicaminyl-uracil in amide linkage with fatty acids which differ in certain respects from those present in the tunicamycins. The corynetoxin acids are of slightly longer chain length, C15-C19, occur in a β-hydroxy as well as saturated and α,β-un-saturated series, and have anteiso, iso and normal chain terminations. β-Hydroxy acids have not been observed previously in the tunicamycin group and anteiso chains were reported only recently in the streptovirudin subgroup. Stereochemical identity of the C11-aminosugar in the corynetoxins with the tunicamine part of the tunicamycins is demonstrated by formation of a common hydrolysis product, di(N-trifluoro- acetyl)glucosaminyl-tunicaminyl-uracil. Analysis of the carbon-13 and proton n.m.r. spectra of the main components, corynetoxins H17a and U17a, confirms the stereochemistry proposed for tunicamine except that the glycosidic linkages are changed to α-galactosamine, β-glucosamine.

Monensin Fortied Corn Supplements in Combination with Testosterone-Estradiol Implants and Vaginal Devices for Finishing Heifers on Pasture

Sixty crossbred heifer calves were fed to slaughter weights using a grain-on-grass finishing system. As a supplement to annual ryegrass pasture, five lots were fed cracked shelled corn ad libitum and five lots were fed the same corn diet plus 66 ppm monensin. Two heifers within each lot were not treated, two heifers were implanted with testosterone-estradiol implants (Synovex-H®) and two heifers were fitted with vaginal devices (HEI-GRO®). Monensin additions did not affect (P>.05) average daily gain but did reduce (P<.05) corn intake and improve (P<.05) supplemental corn/or ryegrass pasture utilization. Monensin reduced ad libitum intake of the cracked corn supplement by an average of 25% and thus indicated promise as a desirable intake limiter of supplement when cattle are self-fed on pasture. Implanted heifers gained faster (P<.05) than control or deviced heifers. Treatment had no effect on carcass characteristics.

Survival of annual ryegrass (Lolium rigidum Gaud.) in a Mediterranean type environment. 1. Effect of summer grazing by sheep on seed numbers and seed germination in autumn

Annual ryegrass–subterranean clover pastures that produced about 5000 kg total dry weight per hectare and 23,500 ryegrass seed per sq metre in spring were grazed by sheep at different stocking rates during summer. Intensive stocking equivalent to about 3000 sheep days ha-1 reduced seed numbers by 20%. Under continuous grazing, about 70% of the seed produced in spring fell readily to the ground during summer. The remaining seed was firmly held in seed heads, and apparently sheep ate mainly this component. Less than 1% of the seed ingested was voided in the faeces. No significant changes in seed numbers over summer were observed in ungrazed pasture. Subsequently, at the break of season in autumn, germination of seeds was examined in situ near the soil surface. The summer grazing history of pastures influenced the percentage of seeds that germinated; more seeds germinated in heavily than in leniently grazed pastures. Whether the pasture was leniently or heavily grazed, there was little effect on germination of shed seeds. Seeds in seed heads were found to germinate more slowly than seeds shed to the soil surface. Seedling emergence in autumn was regulated mainly by the interrelationship between the germination rate of the seed population, depending on summer-early autumn rains, and the period for which favourable moisture conditions prevailed at the soil surface after rain began in autumn. In the field, temperature and light appeared to be unimportant in influencing germination at the break of season. Dynamics of seed and seedling numbers in annual ryegrass pastures in a Mediterranean type environment, particularly at the break of season, are discussed.

Effect of stocking rate, lambing time and pasture management on wool and lamb production on annual subterranean clover pasture

Border Leicester x Merino ewes mated to Dorset Horn rams grazed subterranean clover and annual ryegrass pasture in a 2 x 2 x 4 factorial arrangement having two stocking rates (8.1 and 12.3 eweslha); two lambing times—winter (May, June, July), and spring (August, September); and four management systems, viz. set stocking (SS), autumn saving and spring hay cut (AS), replacement of half the pasture by oats or lucerne (ISP), and replacement of half the pasture by both oats and lucerne, a quarter each (2SP). The percentage of lambs born to ewes mated was lowest from May lambing and progressively increased up to August–September lambing. However, although July lambing produced marginally fewer lambs with slower growth rates than August–September lambing, the difference was not significant and the extra time available with July lambing for lambs to reach a marketable liveweight before pasture senescence meant that the earlier lambing treatment actually produced more prime lambs. The set stocking and autumn saving systems resulted in greater annual wool and lamb production than the substitute pasture systems. Any extra fodder available from oats or lucerne in those treatments failed to make up for losses in animal production associated with a reduction in available fodder during the crop preparation phase. Deterioration of annual pasture caused by plant losses associated with intermittent grazing may have reduced production further in substitute pasture treatments. The results suggest that in southern Australia on annual subterranean clover pasture the optimum level of stocking and the pasture management strategy for prime lamb production can be assessed by a careful observation of the botanical succession taking place, especially if the pasture is continuously grazed. The results also suggest that optimum fertility should be foregone in favour of an earlier lambing, in order to provide sufficient time before pasture senescence for lambs to reach a marketable liveweight. The optimum time for lambing for prime lamb production for a particular region will depend on the time of year when the pasture in the region normally matures.