ANSC 318 1st Edition Lecture 15 Outline of Last Lecture I Hay Losses Strategies to Reduce Field and Storage Losses and Silages Outline of Current Lecture II Grass Tetany a Condition and Clinical Signs b Causes c Magnesium Availability d Animals at Risk e Preventative Management f Treatment III Pulmonary Emphysemia a Conditions b Cause c Treatment Prevention IV Dallisgrass Poisoning or Bermuda Tremors a Condition b Causes c Treatment d Prevention V Nitrate Toxicity a General Background b Clinical Signs c Physiology of Nitrate Toxicity d Treatment e Prevention VI Prussic Acid Poisoning a Condition b Cause c Clinical Signs d Prevention e Treatment f General Rule VII Kleingrass Toxicity VIII IX Fescue Toxicity These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Clinical Signs b Prevention Current Lecture Grass Tetany happens winter wheat low in Magnesium Mg aka wheat pasture poisoning and hypomagnesemia Conditions Clinical Signs animal staggers twitches falls down and is unable to get up low muscle Mg level cause loss of muscle control animals die from muscle convulsions cow can die within hours of observed clinical signs if now treated right away Clinical Signs uneasiness nervousness muscle twitching excitable belligerent in coordination alert but recumbent cow increased rectal temperature convulsions severe cases may die but mild will survive Causes lack of Mg being absorbed from forage hence a Mg deficiency low blood Mg levels will cause Mg to be pulled from muscle tissues because bone Mg is a not readily available source for the animal to use to prevent Mg deficiencies dietary supplementation of Mg is needed Magnesium Availability Mg may not be fully available from forages Factors that inhibit Mg absorption low Ca and Mg levels in forages high K levels high protein levels high levels of other organic compounds grazing fall and winter grain pastures which are undergoing periods of rapid growth will most likely lead to increased cases of grass tetany Animals at Risk Cattle are most prone to grass tetany 1 Pregnant cows last trimester 2 lactating beef cows first 2 months of lactation 3 older cows are more susceptible than younger beef cows Preventative Management 1 acid sandy soil East TX apply limestone to the soil 2 do not apply limestone to high alkaline soils 3 graze older dry cows or stocker calves if pastures tend to cause grass tetany feed Mg Oxide 2 oz cow day Mg Oxide is not palatable and is expensive not recommended in liquid form tastes terrible and cattle will not eat it mixing Mg into range cubes is recommended high Mg mineral blocks aren t guaranteed to prevent grass tetany since cows may not consume enough of the supplement Treatment if diagnosed soon inject Ca P Mg gluconate solution into jugular vein Pulmonary Emphysemia aka Fog Fever or Lungers found in Bermudagrass Conditions severe lung involvement from sensitivity allergic reaction lungs fill with air not fluid lungs expend but don t contract causes gasping contracted rapture can occur older cows more susceptible brahman cows less susceptible cows die from lack of oxygen or quickly getting excited Causes Rumen microbes convert tryptophan to 3 methylindole cows calves are immune get it from grazing immature lush pastures up to 5 14 days of age or regrowth after cutting takes time for reaction to set up usually 1 2 weeks after cattle are put on pasture can be caused by other grasses Treatment Prevention 1 slowly remove cattle from pasture too fast and they will get excited and will not be able to breath 2 let pasture mature for 2 weeks before grazing 3 inject atropine and antihistamine to improve lung function antibiotics will help secondary infection remove from pasture before treating 4 rumensin 200 mg hd day may help to prevent pulmonary emphysemia not common in horses Dallisgrass Poisoning or Bermuda Tremors happens when dallisgrass is infected with ergot or from bermudagrass Condition cattle get hyper excited when scared spooked appear normal but stumble fall when chased usually do not die Causes Dallisgrass Poisoning caused by ergot on the seed head of mature Dallisgrass seed has been replaced by fungus Bermudagrass Tremors caused by fungus associated with tremorgenic mycotoxin cattle typically develop tremors while grazing tall bermudagrass pastures keep bermudagrass short Treatment supportive care with feed and water slowly remove cattle from bermudagrass pasture will recover when they get off the pasture antibiotics may help recover Prevention shred mature dallisgrass to get seed heads off 8 high keep Bermudagrass grazed down never let it get high bermudagrass if severe burn the field do not use bermudagrass for hay in case of toxicity bermudagrass can t be shredded since it is not only in the seed head Nitrate Toxicity General Background nitrate NO3 concentrations are often elevated in forage seldom in concentrates factors causing nitrate elevations drought frost damage shading herbicide treatment high nitrate in the soil fertilizing can be found in any sorghum nitrates metabolized in the GIT by anaerobic microbes and are reduced to ammonia NO3 NO2 N2O5 NO2 NO NH2OH NH3 Nitrate nitrite nitrogen oxides hydrozylamine ammonia nitrite oxidizes hemoglobin Fe to methemoglobin Fe which can t carry O2 fetus is susceptible to methemoglobin leading to death abortion doesn t affect horses or pigs Clinical Signs 5 4 hours post ingestion colic pain diarrhea dyspnea muscular tremors staggering gait cyanosis not moving O2 abortion head back death without struggle blood chocolate brown Physiology plant nitrate nitrite in rumen some nitrite can be converted to ammonia which is used to synthesize microbial protein nitrite much more toxic to animal than nitrate forages with elevated nitrate levels will not affect horses pigs because they lack microbial fermentation Treatment Methylene blu 8 8 mg kg IV administer EXTREMELY SLOWLY Prevention have nitrate levels analyzed 0 0 1 NO3 is safe to feed 1 1 5 NO3 can be fed if limited to total DMI day feed 1 lb head day of feed for every 1 you are over 1 1 5 NO3 is not safe Prevention type and quantity of diet fed will affect the degree of nitrate toxicity displayed nitrates are released more slowly in fresh forages than dry ones when starch CHO supplements from concentrate feeds are fed less nitrites will be absorbed since more NO3 and NO2 will be converted to ammonia and