Production Research Priorities and PRG Endophyte Toxicity

1. Production Research Priorities and PRG Endophyte Toxicity By R A Leng Emeritus Professor UNE

2. An animal nutritionist interest in endophyte toxicity? • Prior to 1996 –As a nutrition researcher never considered possibility of endophyte ill thrift—Puzzled by low productivity of experimental animals particularly in New Zealand grazing PRG. • Since 1996 ---increasing awareness of ill thrift and sudden death of livestock in many different grazing areas I visited on lecture tours • Led me to research literature on ill thrift which ultimately convinced me of major insidious problems associated with endophytic fungus [Leng 2000] • Few if any nutrition or production researchers consider endophytes. e g team at Lincoln NZ working on effects of parasites/nutrition interaction. Blaxter’s energy requirements team [Autumn PRG vs Spring PRG]

3. Endophyte Toxicosis Goes Largely Unrecognised • Producers who are not looking for a fescue toxicity problem [and PRG toxicity] are much less likely to detect one than someone who is - so endophyte effects may go unnoticed [Ball 1997]. • The effects of endophytes on annual gains and reproduction are much greater than is generally realized. [Ball 1997] • Research fund providers in Australia have not recognised the economic losses from endophyte toxicosis [Leng 2000]

4. Australia’s research contribution has been miniscule and has not even attempted a survey of the economic losses • Most research has been done on endophyte toxicosis in • Southern states of USA with Tall Fescue pastures growing in hot conditions • New Zealand with perennial rye grass under cool conditions • Research in Australia has been minimal. • Considerable production research has been done on PRG without knowing alkaloid content.

5. Rye Grass Pastures Are Normally Heavily Infected [60-80%] With N.Lolli in Australia Endophyte [Neotyphodium Lolli] in the stem of PRG.

6. Neotyphodium spp are not restricted to PRG • A number of grasses contain Endophytes Including Australian native Echinopogan Ovatus that is found in all States and contains a Neotyphodium sp that caused staggers and death of sheep in the Tenterfield area as far back as 1890

7. Anecdotal evidence of production losses in cattle and sheep in Australia

8. PRG staggers is common in Victoria and Tasmania on the spring PRG shoot Diarrhea in lambs on PRG, appears to be associated with Endophyte toxicosis. The amounts of dags and fly strike are highly correlated. Diarrhea and endogenous protein loss are associated Heat stress has been associated with consumption of endophyte PRG. Death rates from crowding into dams with subsequent drowning have been recorded on PRG pastures in hot weather

9. Sheep and cattle even on relatively cool days will get into water or seek shade for no apparent reason When you go looking for endophyte toxicity symptoms they are apparent through out the country

10. Evidence of likely production losses from NZ [cool climate] and Southern USA [warm climate] research

11. Growth rates of lambs on rye grass and cattle on fescue pastures Cattle on fescue in Southern USA Lambs on rye grass in NZ

12. Heat stress associated with lowered feed intake, is an important factor in ill-thrift on endophyte infected pastures • Cattle generally are poor thermo-regulators. [Their capacity to sweat is about 0.2 of humans] • Breeds with higher capacity to regulate body temperature [greater ability to sweat] are less effected. • The major measured effects • Depressed cow and calf live weight • Reduced fertility particularly in lactating dairy and beef cows • Reduced milk production in dairy and beef cattle

13. Sheep decrease feed intake a environmental temperature rises Friesians reduce feed intake and milk yield as environmental Heat stress increases Grazing Friesian cows change their feeding behavior as temperature rises

14. Ergovaline and lolitrem are both implicated in heat stress in ruminants • Ergovaline decreases blood flow to skin reducing heat dissipation but lolitrem has a heating effect. High body temperatures are associated with low feed intake and often assumed to be the main cause of ill thrift. Body temperature and respiration rate in sheep given a dose of lolitrem B[75ug/kg LW] under cool conditions [McLaey 1999]

15. Australia Is the Sun Burnt Country and THI Is Often Very High One January day in Australia

16. Research Priorities-1. Monitoring • Pasture monitoring • To provide information on variations in endophyte alkaloids • levels of toxins in PRG and how they are effected by soil, soil fertility climate and grazing management • level of toxin effects intake or selection of pasture by cattle, sheep or other herbivores • To provide information on economic losses deaths, body weight, milk, wool, reproductive efficiency • To provide information where research is being undertaken on other management factor e g • Parasite control and production • Supplementary feeding strategies etc

17. Research Priorities 2.Thermal stress • Establish the production responses to endophyte alkaloids in relation to thermal stress [THI]. Potential for early warning of risk problems and for establishing heat ameliorating management practices. • Shade • Yard work • Supplementary feeding [e g substitute feeding or alternative pastures]

18. Research Priorities 3 –other economic effects • Diarrhoea • Incidence • Effects in animals under thermo-neutral and hot conditions • Cost • Dagging • Fly strike • Production losses

19. Implication of diarrhoea • Ill-thrift has many causes either single or multiple and interactive • The symptoms are simply reduced production [which is often clear to the producer] associated with reduced feed intake [which is not apparent to the producer] • Reduced feed intake is very often associated with inflammatory cytokines and leptin secretion • The persistent diarrhoea may implicate inflammation of the gut wall and indirectly the immune system

20. Research Priorities 4 Interactions • Seems safe to suggest that if there are animals dying from heat stress or misadventure caused by heat stress then most animals will be subject to reduced feed intake and some form of ill-thrift. • Grazing animal production is complex and there are potentially many interacting factors as is clear from recent studies on the interaction of protein requirements with parasites, immuno nutrition and physiological state

21. Research Priorities 5. Protein nutrition, parasite/disease challenge/climate

22. The highest levels of alkaloids in PRG occur in mature pasture on fertilised land. Dry pasture Green pasture

23. Deficiencies of Growth Factors Alter the Flow of Fermentation Intermediates Into Absorbed Nutrients Well balance growth medium Deficient medium Digestible forage Digestible forage 1.0 1.0 Fermentation intermediates Fermentation intermediates 0.66 0.83 0.17 0.34 Short chain organic acids + methane + heat Microbial cells Short chain organic acids + methane + heat Microbial cells

24. Priorities for Research—6 Implications of the immune system • Environments where the sum of environmental and immunological stressors is high divert nutrients away from accretion in muscle, milk and wool to liver anabolism and host defence mechanisms [Husband 1995] • Physical and psychological stressors can activate the acute phase response with potential [Colditz 2002] [calves on slippery floors] • Immune activation then is a primary factor in reduced feed intake and reduced production

25. Parasites of the small intestine progressively reduce feed intake Steele 1996 Essential amino acids, in late pregnancy and early lactation are prioritised for lamb and milk production. Lowering immune function Donaldson 1999 Both the immune competence and the feed intake effects are overcome by increasing in metabolisable protein intake Van Houtert et al 1996

26. Effects of parasitism on the nutrient economy of small ruminants Muscle Epithelia cell turnover tissue repair Microbe & diet protein Muscle protein breakdown increase Skeletal Gut Plasma protein leakage Albumin /globulins from liver increase Wool or Hair decrease VFA Energy Local inflammatory response Growth of foetus Milk Peripheral Inflammatory response

27. Endophyte toxicosis is likely to interact with climate, physiological state and demand for nutrients and disease incidence • Ruminants on imbalanced feeds[ dry forages] reduce feed intake and increase wasteful metabolism and therefore are more prone to heat stress[ the need for a balanced rumen vs imbalanced] • Metabolisable protein requirements are increased • in late preg. early lactation and at weaning • when the immune system is stimulated by foreign bodies, stress and deficiencies of key nutrients • by the need to repair damaged areas of the gut • by increased secretion of mucous in the intestines • by increased drain of endogenous and microbial protein to the lower gut • The metabolisable protein requirements to prevent the periparturient rise in parasite egg production in ewes is about 350g protein or 30% greater then book requirements

28. Research Priorities- 7 Discipline oriented • Study metabolism in the rumen and the site of absorption of the alkaloids--- using labelled alkaloids and cannulated animal [Hill 2005] • Study potential of a range of chemicals to adsorb the alkaloids • Examine the effects of alkaloids on the immune system • Understand the effects on the gut • Understand transfer to foetus and milk[?]. • Measure their effects on the immune system, illeum wall and protein flow to the caecum large intestine[ site of provitamin B12 absorption] Radiolabelled Peptide Ergot Alkaloids. 83.Mitteilung über MutterkornalkaloideEmil SchreierBiopharmaceutical Department, Division of Pharmaceutical Research and Development, Sandoz Ltd., CH-4002 BaselHerrn Dr. Albert Hofmann zum 70. Geburtstag gewidmet

29. A number of binders including bentonite prevent absorption of aflatoxins Bentonite increases wool growth [Fenn and Leng 1985] in sheep by increasing microbial protein supply [Klieve 2002] Bentonite clays strongly bind ergot alkaloids between ph 2-8 but dissociate at Ph 8.5 Site of absorption of lysergic acid is from the rumen [Hill 2005] Grazier observation. Under field conditions wool growth is increased by feeding bentonite and scouring is eliminated or reduced in sheep .

30. Recombinant DNA ? • Is their a role for recombinant RNA to metabolise endophyte alkaloids. • Soil organisms will degrade alkaloids • Recent work inducing Fluroacetate detoxification by rumen organisms suggests any thing is possible[ Greig et al 2004]

31. It is likely that the industry will have to live with endophyte infected pastures for a long time, therefore remedial strategies must be developed. Wild card could be climate change in the long term The 3 hottest years of the past century have occurred since 2000

32. The Aussie Cow is just as susceptible to endophyte toxicosis as overseas cows The End