Polioencephalomalacia (PEM), also referred to as cerebrocortical necrosis (CCN), is a neurological disease seen in ruminants that is caused by multiple factors, one of which is thiamine depletion in the body. Thiamine (vitamin B1) is a key chemical in glucose metabolism that, when deficient, is most threatening to neurological activity. In addition to altered thiamine status, an association with high sulfur intake has been observed as a potential cause of PEM. PEM may also be caused by other toxic or metabolic diseases such as: acute lead poisoning or salt poisoning. [1] Cattle, sheep, goat, and other ruminants that are diagnosed with PEM or pre-PEM suffer opisthotonus, cortical blindness, disoriented movement, and eventually fatality, if left untreated. [1] Current data shows that the onset of PEM can range from birth to late adulthood. [2]
Thiamine availability is controlled by the direct dietary consumption of thiamine. Thiamine availability is also regulated by thiaminases, which are enzymes that readily cleave thiamine molecules and inhibit essential thiamine-regulated pathways such as the metabolism of glucose. [3] Ruminants have working rumen microbes that synthesize thiamine molecules for the body; therefore, ruminants do not need to ingest thiamine rich foods for thiamine. [4] However, feed concentrates given to ruminants, specifically sheep and cattle, are often heavily stocked with thiaminases. The presence of thiaminases counter the production of thiamine by breaking them down, resulting in a futile cycle between rumen microbes and thiaminases. Eventually, when the rate of synthesis production can not exceed thiaminase intake, a state of thiamine deficiency will be reached. Thiaminase rich foods include different grains, fresh water fish, and ferns, all of which are often processed together to make feed concentrate. [5] [6]
Since glucose metabolism is regulated by thiamine, the overconsumption of glucose can also result in thiamine inadequacy. [7] When there is a sudden increase of glucose in the body, thiamine will be depleted so that thiamine is not available when the next round of glucose needs to be metabolized.
In light of recent research, high concentrations of sulfur intake have also been deemed responsible for PEM. [8] [9] Sulfur is necessary for the synthesis of important sulfur-containing amino acids and their contribution to the synthesis of different hormones, enzymes, and structural proteins. The ruminant diet, especially that of cattle, can be overly concentrated with sulfur. In ruminants, the same rumen microbes that generate thiamine molecules reduce sulfur into toxic sulfides. Among the sulfide toxins is hydrogen sulfide, a gas compound that will compete with oxygen to bind with red blood cells and eventually enter the brain to disrupt neural activity. [10]
Clinical signs of PEM are variable depending on the area of the cerebral cortex affected and may include head pressing, dullness, opisthotonos, central blindness, anorexia, muscle tremors, teeth grinding, trismus, salivation, drooling, convulsions, nystagmus, clonic convulsions, and recumbency. [11] Early administration of thiamine may be curative, but if the lesion is more advanced, then surviving animals may remain partially blind and mentally dull.
Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient for humans and animals. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of thiamine are required for some metabolic reactions, including the breakdown of glucose and amino acids.
Ketosis is a metabolic state characterized by elevated levels of ketone bodies in the blood or urine. Physiological ketosis is a normal response to low glucose availability. In physiological ketosis, ketones in the blood are elevated above baseline levels, but the body's acid–base homeostasis is maintained. This contrasts with ketoacidosis, an uncontrolled production of ketones that occurs in pathologic states and causes a metabolic acidosis, which is a medical emergency. Ketoacidosis is most commonly the result of complete insulin deficiency in type 1 diabetes or late-stage type 2 diabetes. Ketone levels can be measured in blood, urine or breath and are generally between 0.5 and 3.0 millimolar (mM) in physiological ketosis, while ketoacidosis may cause blood concentrations greater than 10 mM.
Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process, which takes place in the front part of the digestive system and therefore is called foregut fermentation, typically requires the fermented ingesta to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination. The word "ruminant" comes from the Latin ruminare, which means "to chew over again".
Lactic acidosis refers to the process leading to the production of lactate by anaerobic metabolism. It increases hydrogen ion concentration tending to the state of acidemia or low pH. The result can be detected with high levels of lactate and low levels of bicarbonate. This is usually considered the result of illness but also results from strenuous exercise. The effect on pH is moderated by the presence of respiratory compensation.
Wernicke-Korsakoff syndrome (WKS) is the combined presence of Wernicke encephalopathy (WE) and alcoholic Korsakoff syndrome. Due to the close relationship between these two disorders, people with either are usually diagnosed with WKS as a single syndrome. It mainly causes vision changes, ataxia and impaired memory.
Carbohydrate metabolism is the whole of the biochemical processes responsible for the metabolic formation, breakdown, and interconversion of carbohydrates in living organisms.
Alcoholic polyneuropathy is a neurological disorder in which peripheral nerves throughout the body malfunction simultaneously. It is defined by axonal degeneration in neurons of both the sensory and motor systems and initially occurs at the distal ends of the longest axons in the body. This nerve damage causes an individual to experience pain and motor weakness, first in the feet and hands and then progressing centrally. Alcoholic polyneuropathy is caused primarily by chronic alcoholism; however, vitamin deficiencies are also known to contribute to its development. This disease typically occurs in chronic alcoholics who have some sort of nutritional deficiency. Treatment may involve nutritional supplementation, pain management, and abstaining from alcohol.
The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary site for microbial fermentation of ingested feed, which is often fiber-rich roughage typically indigestible by mammalian digestive systems. The rumen is known for containing unique microbial networks within its multiple sac compartments to break down nutrients into usable energy and fatty acids.
Enteric fermentation is a digestive process by which carbohydrates are broken down by microorganisms into simple molecules for absorption into the bloodstream of an animal. FAO estimated that ruminant livestock contribute to around 34.5 percent of the total anthropogenic methane emissions.
Thiamine deficiency is a medical condition of low levels of thiamine (vitamin B1). A severe and chronic form is known as beriberi. The name beriberi was possibly borrowed in the 18th century from the Sinhalese phrase බැරි බැරි (bæri bæri, “I cannot, I cannot”), owing to the weakness caused by the condition. The two main types in adults are wet beriberi and dry beriberi. Wet beriberi affects the cardiovascular system, resulting in a fast heart rate, shortness of breath, and leg swelling. Dry beriberi affects the nervous system, resulting in numbness of the hands and feet, confusion, trouble moving the legs, and pain. A form with loss of appetite and constipation may also occur. Another type, acute beriberi, found mostly in babies, presents with loss of appetite, vomiting, lactic acidosis, changes in heart rate, and enlargement of the heart.
Listeriosis is an infectious but not contagious disease caused by the bacterium Listeria monocytogenes, far more common in domestic animals, especially ruminants, than in human beings. It can also occur in feral animals—among others, game animals—as well as in poultry and other birds.
Dichapetalum cymosum, commonly known as gifblaar from Afrikaans, or occasionally by its English translation, poison leaf, is a small prostrate shrub occurring in northern parts of Southern Africa in the family Dichapetalaceae. It is notable as a common cause of lethal cattle poisoning in this region and is considered one of the 'big 6' toxic plants of cattle in South Africa. A 1996 estimate of plant poisonings in South Africa attributes 8% of cattle mortality caused by poisonous plants to it. The majority (70%) of fatal cases are in Limpopo province, with 10% each in North West, Mpumalanga, and Gauteng. Fluoroacetate, the poison used to synthetically produce Compound 1080 used extensively in New Zealand, occurs in all parts of the plant and is responsible for the toxic effects shown.
Selenium deficiency occurs when an organism lacks the required levels of selenium, a critical nutrient in many species. Deficiency, although relatively rare in healthy well-nourished individuals, can have significant negative results, affecting the health of the heart and the nervous system; contributing to depression, anxiety, and dementia; and interfering with reproduction and gestation.
Grass tetany also called the staggers , is a metabolic disease involving magnesium deficiency, which can occur in such ruminant livestock as beef cattle, dairy cattle and sheep, usually after grazing on pastures of rapidly growing grass, especially in early spring. Despite the name, it is unrelated to tetanus.
Phalaris angusta is a species of grass known by the common names timothy canarygrass and narrow canarygrass. It is native to the Americas, where it is most common in Chile and Argentina and can be found in northern South America and sections of the southwestern and southeastern United States. It is also known as an introduced species in Australia. It grows in grassland, prairie, marshland, and other habitat.
Nutritional neuroscience is the scientific discipline that studies the effects various components of the diet such as minerals, vitamins, protein, carbohydrates, fats, dietary supplements, synthetic hormones, and food additives have on neurochemistry, neurobiology, behavior, and cognition.
Nutritional Muscular Dystrophy is a disease caused by a deficiency of selenium and vitamin E in dietary intake. Soils that contains low levels of selenium produce forages and grains that are deficient in selenium. Similarly, if the forage is of low quality or is not stored properly it may be deficient in vitamin E. If an animal consumes this type of diet without additional supplementation they become susceptible to this disease. This condition often affects young ruminants, such as calves and lambs.
Relatively speaking, the brain consumes an immense amount of energy in comparison to the rest of the body. The mechanisms involved in the transfer of energy from foods to neurons are likely to be fundamental to the control of brain function. Human bodily processes, including the brain, all require both macronutrients, as well as micronutrients.
Molybdenum is an essential element in most organisms. It is most notably present in nitrogenase which is an essential part of nitrogen fixation.
Cobalt is essential to the metabolism of all animals. It is a key constituent of cobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as an ultratrace element. Bacteria in the stomachs of ruminant animals convert cobalt salts into vitamin B12, a compound which can only be produced by bacteria or archaea. A minimal presence of cobalt in soils therefore markedly improves the health of grazing animals, and an uptake of 0.20 mg/kg a day is recommended because they have no other source of vitamin B12.