Association between feeding perennial ryegrass (Lolium perenne cultivar Grasslands Impact) containing high concentrations of ergovaline, and health and productivity in a herd of lactating dairy cows

Feeding Tall Fescue Seed Reduces Ewe Milk Production, Lamb Birth Weight and Pre-Weaning Growth Rate

Simple Summary

This study was conducted to examine how ergovaline/ergovalinine ingestion during pregnancy in ewes with different DRD2 genotypes altered ewe and lamb performance. Feeding ergovaline/ergovalinine in last trimester reduced lamb birth weight; however, milk production was lower for all ewes fed ergovaline/ergovalinine. Lambs born to dams fed ergovaline/ergovalinine had slower growth rates and lower weaning weights. These results demonstrate that ingestion of ergot alkaloids during pregnancy can negatively influence lactation, growth of offspring and birth and weaning weights. Recommendations would include strategies to mitigate mycotoxin exposure in pregnant ewes to improve production.

Abstract

Endophyte-infected tall fescue (E+) produces ergovaline and ergovalinine, which are mycotoxins that act as dopamine agonists to suppress prolactin and induce vasoconstriction. The experiment was designed as a 3 × 2 × 2 factorial with DRD2 genotype (AA, AG, GG), fescue seed (endophyte-free, E− or endophyte-infected, E+), stage of gestation (MID, d (day) 35–85; LATE, d 86–parturition) and all interactions in the model. Pregnant Suffolk ewes (n = 60) were stratified by genotype and fed E+ or E− seed in a total mixed ration according to treatment assignment. Serum prolactin concentrations were lower (p < 0.05) in ewes fed E+ seed but did not differ by maternal DRD2 genotype or two-way interaction. Lamb birth weight was lower (p < 0.05) in ewes fed E+ seed in last trimester. Pre-weaning growth rate, milk production and total weaning weight was reduced (p < 0.05) in ewes fed E+ fescue seed during MID and LATE gestation. Ingestion of ergovaline/ergovalinine in last trimester reduces lamb birth weight; however, lamb growth rate, milk production and total weaning weight are reduced in all ewes fed E+ during mid and last trimester.

Avoidance Distance in Sheltered Cows and Its Association with Other Welfare Parameters

The human-animal relationship is an important welfare parameter in animal welfare assessment in cows, and the avoidance distance of cows to a stranger at the feed bunk is measured to assess this relationship. The assessment of the human-animal relationship in cow shelters in India, where old, unproductive, and abandoned cows are sheltered, is important to explore the welfare of cows in these shelters. The cows observed were of indigenous Indian breeds and breeds which were crosses between indigenous breeds and pure bred exotic cows. The human-animal contact in this context is of particular interest for welfare assessment as traditional Indian farming and sheltering systems involves regular close human-animal contact. In a cross-sectional study across 6 states, 54 cow shelters were visited and 30 cows in each shelter were randomly selected (1620 in total) for the assessment of avoidance distance and other cow-based (27 parameters) and resource-based (15 parameters) welfare parameters. Avoidance distance was assessed 1 h after morning feeding. Cows standing at the feeding manger were approached from the front at a rate of one step/s, starting 2 m away from the manger. The distance between the assessor's hand and the cow's head was estimated at the moment the cow moved away and turned its head, using a four-point scale (0, touched; 1, 0-50 cm; 2, 51-100 cm; and 3, >100 cm). The majority, 52%, of the cows allowed touch by the assessor and another 32% allowed approach within 50 cm, demonstrating tolerance, or even solicitation of close human-animal relationships by the cows. Avoidance distance increased with the proportion of cows with dirty hind limbs, tarsal joint swellings, and hair loss, and the extent of rumen fill. There was also evidence of reduced avoidance distances in cows with high levels of body condition score (BCS), dirty flanks, tarsal joint ulceration, carpal joint injuries, diarrhoea, hampered respiration, lesions on the body due to traumatic injuries, and body coat condition, probably as a result of moving difficulties. The avoidance distance was thus related to the health and welfare of the cows, providing a vital insight into the factors affecting human-animal contact in the shelters.

Silage review: Animal and human health risks from silage

Silage may contain several agents that are potentially hazardous to animal health, the safety of milk or other animal food products, or both. This paper reviews published literature about microbial hazards, plant toxins, and chemical hazards. Microbial hazards include Clostridium botulinum, Bacillus cereus, Listeria monocytogenes, Shiga toxin-producing Escherichia coli, Mycobacterium bovis, and various mold species. High concentrations of C. botulinum in silage have been associated with cattle botulism. A high initial concentration of C. botulinum spores in forage in combination with poor silage fermentation conditions can promote the growth of C. botulinum in silage. The elevated pH level that is generally associated with aerobic deterioration of silage is a major factor influencing concentrations of L. monocytogenes, Shiga toxin-producing E. coli, and molds in silage and may also encourage survival and growth of M. bovis, the bacterium that causes bovine tuberculosis. Soil is a major source of B. cereus spores in silage; growth of this bacterium in silage appears to be limited. Hazards from plant toxins include pyrrolizidine, tropane and tropolone alkaloids, phytoestrogens, prussic acid, and mimosine, compounds that exist naturally in certain plant species that may contaminate forages at harvesting. Another group of toxins belonging to this category are ergot alkaloids, which are produced by endophytic fungal species in forages such as tall fescue grass, sorghum, and ryegrass. Varying effects of ensiling on the degradation of these plant toxins have been reported. Chemical hazards include nitrate, nitrite, and toxic oxide gases of nitrogen produced from nitrate and high levels of butyric acid, biogenic amines, and ammonia. Chemical and microbiological hazards are associated with poorly fermented silages, which can be avoided by using proper silage-making practices and creating conditions that promote a rapid and sufficient reduction of the silage pH and prevent aerobic deterioration.

Ergovaline, an endophytic alkaloid. 1. Animal physiology and metabolism

Ergovaline is an ergot alkaloid found in some endophyte-infected ryegrasses and it has been implicated in the expression of ergotism-like symptoms of grazing livestock, as well as in the protection of the plant against invertebrate predation and abiotic stresses. These selection pressures have resulted in a conflict between the needs of the pasture for persistence and the needs of the animal for production. Ergovaline has not been well studied in terms of animal physiology until recently. There are several putative mechanisms that limit the bioavailability of ergovaline, ranging from microbial biotransformation to post-absorptive hepatic detoxification. Although there are mechanisms that protect the animal from ergovaline exposure, tissues are very sensitive to ergovaline, indicating that ergovaline is very potent and that small quantities have the potential to cause noticeable physiological effects. The range of physiological effects, including decreased circulating prolactin, vasoconstriction and increased susceptibility to heat stress are all linked to the interaction of ergovaline with biogenic amine receptors found throughout the body. This review will focus on understanding the variation of ergovaline concentration in terms of bioavailability, the myriad of hurdles a molecule of ergovaline must overcome to cause an effect, what the ergovaline-induced effects are in New Zealand livestock and how this relates to the potency of ergovaline.

Activities and Effects of Ergot Alkaloids on Livestock Physiology and Production

Consumption of feedstuffs contaminated with ergot alkaloids has a broad impact on many different physiological mechanisms that alters the homeostasis of livestock. This change in homeostasis causes an increased sensitivity in livestock to perturbations in the ambient environment, resulting in an increased sensitivity to such stressors. This ultimately results in large financial losses in the form of production losses to livestock producers around the world. This review will focus on the underlying physiological mechanisms that are affected by ergot alkaloids that lead to decreases in livestock production.

Breaking through the feed barrier: options for improving forage genetics

Pasture based on perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) is the foundation for production and profit in the Australasian pastoral sectors. The improvement of these species offers direct opportunities to enhance sector performance, provided there is good alignment with industry priorities as quantified by means such as the forage value index. However, the rate of forage genetic improvement must increase to sustain industry competitiveness. New forage technologies and breeding strategies that can complement and enhance traditional approaches are required to achieve this. We highlight current and future research in plant breeding, including genomic and gene technology approaches to improve rate of genetic gain. Genomic diversity is the basis of breeding and improvement. Recent advances in the range and focus of introgression from wild Trifolium species have created additional specific options to improve production and resource-use-efficiency traits. Symbiont genetic resources, especially advances in grass fungal endophytes, make a critical contribution to forage, supporting pastoral productivity, with benefits to both pastures and animals in some dairy regions. Genomic selection, now widely used in animal breeding, offers an opportunity to lift the rate of genetic gain in forages as well. Accuracy and relevance of trait data are paramount, it is essential that genomic breeding approaches be linked with robust field evaluation strategies including advanced phenotyping technologies. This requires excellent data management and integration with decision-support systems to deliver improved effectiveness from forage breeding. Novel traits being developed through genetic modification include increased energy content and potential increased biomass in ryegrass, and expression of condensed tannins in forage legumes. These examples from the wider set of research emphasise forage adaptation, yield and energy content, while covering the spectrum from exotic germplasm and symbionts through to advanced breeding strategies and gene technologies. To ensure that these opportunities are realised on farm, continuity of industry-relevant delivery of forage-improvement research is essential, as is sustained research input from the supporting pasture and plant sciences.

Ergot alkaloid intoxication in perennial ryegrass (Lolium perenne): an emerging animal health concern in Ireland?

Four primary mycotoxicosis have been reported in livestock caused by fungal infections of grasses or cereals by members of the Clavicipitaceae family. Ergotism (generally associated with grasses, rye, triticale and other grains) and fescue toxicosis (associated with tall fescue grass, Festuca arundinacea) are both caused by ergot alkaloids, and referred to as ‘ergot alkaloid intoxication’. Ryegrass staggers (associated with perennial ryegrass Lolium perenne) is due to intoxication with an indole-diperpene, Lolitrem B, and metabolites. Fescue-associated oedema, recently described in Australia, may be associated with a pyrrolizidine alkaloid, N-acetyl norloline.

Ergotism, caused by the fungus Claviceps purpurea, is visible and infects the outside of the plant seed. Fescue toxicosis and ryegrass staggers are caused by Neotyphodium coenophalium and N. lolii, respectively. Fescue-associated oedema has been associated with tall fescue varieties infected with a specific strain of N. coenophialum (AR542, Max P or Max Q). The name Neotyphodium refers to asexual derivatives of Epichloë spp., which have collectively been termed the epichloë fungi. These fungi exist symbiotically within the grass and are invisible to the naked eye.

The primary toxicological effect of ergot alkaloid involves vasoconstriction and/or hypoprolactinaemia. Ingestion of ergot alkaloid by livestock can cause a range of effects, including poor weight gain, reduced fertility, hyperthermia, convulsions, gangrene of the extremities, and death. To date there are no published reports, either internationally or nationally, reporting ergot alkaloid intoxication specifically associated with perennial ryegrass endophytes. However, unpublished reports from the Irish Equine Centre have identified a potential emerging problem of ergot alkaloid intoxication with respect to equines and bovines, on primarily perennial ryegrass-based diets. Ergovaline has been isolated in varying concentrations in the herbage of a small number of equine and bovine farms where poor animal health and performance had been reported. Additionally, in some circumstances changes to the diet, where animals were fed primarily herbage, were sufficient to reverse adverse effects. Pending additional information, these results suggest that Irish farm advisors and veterinarians should be aware of the potential adverse role on animal health and performance of ergot alkaloids from perennial ryegrass infected with endophytic fungi.

A review of the Neotyphodium lolii / Lolium perenne symbiosis and its associated effects on animal and plant health, with particular emphasis on ryegrass staggers

Ryegrass staggers is a seasonal mycotoxicosis of grazing livestock characterised by tremors, in coordination and a staggering gait almost unaccompanied by physical lesions. Deaths occur only as a consequence of accident or starvation. Outbreaks, in summer and autumn, occur only on pasture in which endophyte (Neotyphodium lolii)-infected perennial ryegrass (Lolium perenne) predominates and usually on which animals are grazed intensively. Animals recover when moved to a different type of grazing or after rain has promoted pasture growth. The disease was recognised for 80 years before its cause was discovered as a consequence of a grazing trial of sheep on three ryegrass cultivars which happened to have three different levels of endophyte infection. The endophyte was first formally described as Acremonium loliae, later corrected to Acremonium lolii, and was finally placed in the genus Neotyphodium. It produces a number of secondary metabolites of which lolitrem B is the principal one causing ryegrass staggers symptoms. Ergopeptides are also produced which cause heat stress and lack of productivity. N. lolii is symptomless in the plant, seed borne and grows intercellularly in the aerial parts, mainly in reproductive tillers and leaf sheaths but sparsely in leaf blades. It dies in stored seed and infection rates of different ryegrass cultivars have depended on seed storage times during their production. In addition, N. Lolii produces insect feeding deterrents, among them peramine, which protects infected plants from pest predation. Because of this, control of ryegrass staggers by elimination of endophyte-infected ryegrass is not feasible in areas in which insect predation is a serious pasture problem. However, N. lolii strains vary in the secondary metabolites they produce allowing the selection of strains that produce desirable metabolites. By inoculating such strains into uninfected ryegrass plants it is possible to produce cultivars which do not cause ryegrass staggers but resist insect predation. This review aims to provide a comprehensive summary of the current understanding of the N. lolii / L. perenne symbiosis, the toxins it is known to produce, their effects on animals and plants and the strategies used to control their ill effects while maximising their beneficial ones.

Effects of wild-type, AR1 and AR37 endophyte-infected perennial ryegrass on dairy production in Victoria, Australia

A 3-year experiment compared the effects of wild-type ryegrass endophyte and two novel endophytes on milk production in dairy cattle. On three 9.9-ha farmlets in West Gippsland, Victoria, pasture swards were established that were dominant in perennial ryegrass (Lolium perenne) infected with either wild-type, AR1 or AR37 endophytes. Each farmlet was stocked with 25 spring-calving Holstein–Friesian cows, which rotationally grazed nine paddocks within their farmlet during three lactations over 3 years. The three endophytes are known to produce different alkaloids, with wild-type producing ergot alkaloids, lolitrems and peramine, AR1 producing peramine and AR37 producing epoxy-janthitrems. These alkaloids were present in fresh pasture as well as hay and silage made from that pasture. Grazed pasture comprised 53% of estimated annual DM intake. The proportion was least from December to March when the daily ration of 2 kg DM/cow.day cereal grain was increased to 6 kg/day and forage supplements were fed consisting of purchased lucerne (Medicago sativa) hay and pasture silage grown on the farmlets. There were no differences in pasture accumulation rates or nutritive characteristics of ryegrass pastures on the three farmlets and no differences in the production of milk, fat or protein by cows grazing pasture infected with the three endophytes. Ryegrass staggers was only observed in four cows consuming the wild-type-infected ryegrass in the first year when the highest concentrations of lolitrem B were recorded in pasture. Soil samples showed lower numbers of root aphids (Aploneura lentisci), mealybugs (Pseudococcidae) and pasture tunnel moths (Philobota spp.) beneath ryegrass infected with the AR37 endophyte compared with the other two endophytes. Numbers of redheaded (Adoryphorus couloni) and blackheaded (Aphodius tasmaniae) cockchafers did not differ between treatments. Under dairy management and supplementary feeding regimes common to south-eastern Australia, the novel endophytes AR1 and AR37 had no effect on the milk production compared with the wild-type endophyte, and did not cause ryegrass staggers.

ESI-Mass spectrometric and HPLC elucidation of a new ergot alkaloid from perennial ryegrass hay silage associated with bovine reproductive problems

This case report involves four dairies in the Willamette Valley, Oregon, which experienced reproductive problems associated with the presence of a large, previously unidentified, peak eluting at 5 min in a standard ergovaline high-performance liquid chromatography assay of perennial ryegrass silage fed to those animals. Mycotoxin analysis of the silage was negative, as was serological screening of the herds for infectious bovine rhinotracheitis, bovine diarrhea virus and Leptospirosis, including culturing of urine for Leptospira hardjo hardjobovis. Prolactin concentrations were low in most cattle, consistent with ingestion of ergot alkaloids. We believe that this peak represents a novel ergot alkaloid-related compound due to its extractability with Ergosil, its detectability due to fluorescence, and its chromatographic retention between ergovaline (mw = 533) and ergotamine (mw = 581). Its molecular weight was calculated as 570 owing to the predominance of a m/z 593.5 ion in the full scan ESI(+)MS and its deduced tendency to complex with Na(+) (as m/z 593) or K(+) (as m/z 609) ions. We offer rationales for elucidation of the structure of this compound, with the closest starting point comprising an m.w. of 566-a fructofuranosyl-(2-1)-O-beta-D-fructofuranoside derivative of 6,7-secoergoline from Claviceps fusiformis. This m.w. requires modifications, such as reduction of two double bonds in the secoergoline component to give the target 570 m.w. Despite the lack of a definitive structure, the analysis herein provides a starting point for eventual elucidation of this apparently new ergot alkaloid, and to guide and encourage further investigation as to its association with endophyte toxicosis in livestock.

Fluctuations in the concentration of ergovaline and lolitrem B produced by the wild-type endophyte (Neotyphodium lolii) in perennial ryegrass (Lolium perenne) pasture

Mammalian toxins produced by the wild-type endophyte, Neotyphodium lolii, in perennial ryegrass (PRG) pasture cause production losses and animal health and welfare problems in livestock. Managing this risk is limited by the lack of information on fluctuations in the concentration of toxin in Australian pasture. We investigated how the toxin concentrations may be related to recent observations of weather. Swards sown from common seedlots of two cultivars of wild endophyte-infected PRG, grazed short by sheep, were sampled at 2–4 weekly intervals from spring to autumn at two sites in Victoria. The highest concentration of ergovaline and lolitrem B was observed at Hamilton, the site with the longer-growing season. The concentration of ergovaline peaked in early summer, coinciding with seed development, and declined through summer, before increasing with the commencement of autumn growth. The concentration of lolitrem B remained low in summer, then rose in autumn. Variation between the two cultivars in the concentration of toxins was small and rarely significant. The concentration of ergovaline declined as the mean daily maximum temperature over the preceding 1–5 days increased. Similarly, for lolitrem B, the concentration declined over the temperature range 12−20°C, from 1.3 to 0.3 mg/kg. At Hamilton, where solar radiation and soil temperature were recorded, both were superior to maximum temperature for predicting lolitrem B. Serial sampling of PRG from old naturalised pasture on seven farms across south-eastern Australia found two seasonal peaks for both alkaloids in most pastures. The concentration of ergovaline reached or exceeded tolerance levels for livestock in 23 of 43 samples, compared with 5 of 43 for lolitrem B. Ergovaline concentrations initially peaked (at 1.0–1.6 mg/kg) when mature reproductive material was present (coinciding with peduncle elongation and seed development). In pastures with low grazing pressure, i.e. where growth was allowed to continue through summer, ergovaline concentration was relatively low (<0.7 mg/kg) but in a hard-grazed pasture (sward height 3 cm), the ergovaline concentration was greater (up to 1.1 mg/kg). Concentration of lolitrem B also peaked in December, except on pasture where growth continued through summer. High concentrations of lolitrem B associated with neurotoxic signs in sheep (viz. 2.4–3.9 mg/kg) were observed only in mid-summer and autumn, and only if conditions favoured growth or where close grazing by sheep left the crown as the dominant source of herbage.

Evaluation of perennial ryegrass straw as a forage source for ruminants1

Two experiments were conducted to evaluate perennial ryegrass straw as a forage source for ruminants. Experiment 1 evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231+/-2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (<100 and 1,550 ppb, respectively; DM basis) were used to formulate treatment diets: 100% L; 67% L:33% H; 33% L:67% H; 100% H (DM basis). Intake and digestibility of DM and OM, and ruminal pH, total VFA, and NH3-N were not affected by increasing lolitrem B concentration. Ruminal indigestible ADF (IADF) fill increased linearly (P = 0.01) and IADF passage rate decreased linearly (P = 0.04) as lolitrem B increased. Experiment 2 evaluated performance and production by 72 Angus x Hereford cows (539+/-5 kg BW) consuming perennial ryegrass straw containing increasing lolitrem B during the last third of gestation. Cows were blocked by body condition score and randomly assigned to one of three treatments. Cows were provided perennial ryegrass straw ad libitum and supplemented with soybean meal (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Mixtures of a L and H lolitrem B straw (467 and 2,017 ppb, respectively) were used to formulate treatment diets: 100% L, 50% L:50% H, 100% H (DM basis). Thirteen of 24 cows on the 100% H treatment exhibited signs of ryegrass staggers and were removed from the study; nevertheless, lolitrem B concentration did not influence pre- or postcalving weight or body condition score change. These data suggest that feeding perennial ryegrass straw containing up to 1,550 ppb lolitrem B (DM basis) did not adversely affect nutrient digestion or physiological response variables in steers. However, providing straw with a lolitrem B concentration of approximately 2,000 ppb (DM basis) resulted in 54% of cows exhibiting signs of ryegrass staggers. These data suggest that blending straws with a high (>2,000 ppb) and low (<500 ppb) concentration of lolitrem B can be a successful management practice.

Gene flow in the endophyte Neotyphodium and implications for coevolution with Festuca arizonica

Arizona fescue (Festuca arizonica) often harbours asymptomatic, asexual endophytic fungi from the genus Neotyphodium. In agronomic grasses, Neotyphodium endophytes are often credited with a wide range of mutualistic benefits to its host many of which are related to fungal production of alkaloids for herbivore deterrence. Neotyphodium in the native grass Arizona fescue, however, usually produces alkaloids at levels too low to deter herbivores, and in general, does not behave mutualistically. This study uses microsatellite markers to examine rates of gene flow among four Arizona populations of Neotyphodium. Haplotypic diversity was generally low; only one population contained more than two haplotypes. Haplotypes carrying multiple loci for some or all of the microsatellite loci were also found, indicating a vegetative hybridization event between Neotyphodium and the grass choke pathogen from the genus Epichloë. Gene flow between Neotyphodium populations is very low, and likely much lower than the pollen mediated gene flow of its host. These differing rates of gene flow are predicted to create trait mismatching between endophyte and host and may explain the low, or lack of, alkaloid production by Neotyphodium in Arizona fescue and other native grass species.

Ryegrass endophyte (Neotyphodium lolii) alkaloids and mineral concentrations in perennial ryegrass (Lolium perenne) from southwest Victorian pasture

On all of 120 farms in south-west Victoria that were selected at random and sampled during autumn and winter over 2 years, perennial ryegrass was present in the pasture and tested positive for the presence of the naturally occurring ryegrass endophyte, Neotyphodium lolii (mean frequency 78%). Ryegrass staggers were reported on 33% (1999) and 43% (2000) of the surveyed farms. Clinically significant concentrations of lolitrem B were detected in perennial ryegrass samples with concentrations in the range 0–4.44 mg/kg. Concentration exceeded 1.8 mg/kg in 37% of pastures indicating an inherent, widespread problem for livestock farmers. Concentration was independent of endophyte frequency, pasture age, pasture height, annual rainfall and origin of sown cultivar. Ergovaline was detected in most of the perennial ryegrass samples with concentrations up to 3.90 mg/kg. In 1999, the mean concentration of ergovaline was 0.76 (± 0.70) mg/kg with 33% of pastures having a level >0.4 mg/kg, the level associated with heat stress in cattle. In 2000, sampling was carried out later in the year than for the 1999 survey and the mean concentration of ergovaline was 0.12 (± 0.10) mg/kg; 3% of samples exceeded 0.4 mg/kg. The mean concentration of peramine was 13.7 (± 6.6) mg/kg in the 1999 survey and 4.2 (± 5.1) mg/kg in the 2000 survey. Mineral analysis indicated that perennial ryegrass nutrition was inadequate with regard to phosphorous on 17% of the dairy pastures and on 37% of the sheep/beef pastures. Potassium was deficient in perennial ryegrass on 5 and 37% of dairy and sheep/beef pastures respectively. For perennial ryegrass in sheep/beef pastures, 25% were deficient in sulphur. For lactating cattle having only perennial ryegrass as a food source, phosphorous and copper concentrations in the grass were inadequate on 80% of the pastures. Calcium, zinc, magnesium, potassium and sulphur concentrations in perennial ryegrass were also inadequate on some pastures. However, with 1 exception, the ratio [K/(Ca+Mg) expressed as equivalents] was less than 2.2, the level associated with the development of hypomagnesemia. Hypomagnesemia (grass tetany) was therefore unlikely to be a major cause of the staggers syndrome. Lolitrem B was negatively correlated with grass potassium concentration (P<0.001). Ergovaline was negatively correlated with date of sampling (P<0.001). Peramine concentration was positively correlated with endophyte frequency, the potassium and sodium concentrations in perennial ryegrass and negatively correlated with date of sampling. The need for research on the economic impact and management of pasture contaminated with ryegrass endophyte toxins is discussed.