Mycotoxins in dairy cattle

Dr Anas Ahmed Khan
Mycotoxins:  Effects on Dairy Production

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Introduction: Mycotoxins are biologically diverse toxic secondary metabolites of fungi and are being produced by several mould species including Aspergillus, Fusarium and Penicillium. The occurrence of mould and mycotoxins in food and animal feed is a problem of major concern internationally. Several hundred mycotoxins have been identified and reported in scientific literature yet but few of them pose a sever threat to public health and animal agriculture industry. Various agriculture commodities can be contaminated by moulds and mycotoxins during yield (growth and maturation), harvesting, transportation, storage and feed processing and their adverse effects are manifold. According to Food and Agriculture Organization (FAO) more than 25% of the world grain supply is being affected by mycotoxins annually. They have great economic impact on agriculture and livestock producers and food and feed processors.

The worldwide economic losses due to mycotoxins have been found to be more than several hundred million US dollars per annum and their control is critical. Ruminant species are generally thought to be less sensitive to mycotoxicosis as compared to other food producing animals. Ruminant diets generally include both forages and concentrate which may increase the risk of mycotoxins in comparison with animals that do not consume forages. Millions of tones of forage is being produced by livestock producers and consumed by animals annually and interestingly majority of it is contaminated with fungal species invading forage plants prior to harvest or during storage as hay, straw or silage. Preserved forages like silage are more prone to be contaminated by moulds and their associated mycotoxins than dry forages if anaerobic conditions are not maintained properly. Moreover, the green fodder cannot be considered completely safe from mycotoxin contamination because they are equally prone to be contaminated by fungal endophytes that produce toxins.

Effects of Mycotoxins: The negative effects of mycotoxins on human and animal health has been recognized and reported by scientific community. During World War II a large group of Russian soldiers was found to be affected by a sudden disease showing severe dermal necrosis, hemorrhages and bone marrow destruction and clinical investigations revealed that these soldiers were fed to grains which were contaminated with some species of fungi belong to genus Fusarium. In early 1960s the entire turkey population of Britain was affected by a fetal liver disease known as Turkey X Disease and it was attributed to the feeding of contaminated peanut meal imported from Brazil. This incidence was known to be the major breakthrough in the initiation of studies on mycotoxins referred to as mycotoxicology.

The economic impacts of mycotoxins include loss of human and animal life, increased health care and veterinary care costs, reduced livestock production, disposal of contaminated food and feed and investment in research and applications to reduce severity of mycotoxin problem. Intake of mycotoxins at larger doses can primarily cause acute health and production problems in dairy herds. Generally in field conditions the chronic effects of mycotoxicosis are manifold which include higher incidence of infectious diseases, poor reproductive efficiency and suboptimal milk and meat production. Ruminant have a complex and diversified gastric system and rumen contains a dense and diversified microbial ecosystem (bacteria 1011/ml, protozoa 106/ml and fungi 104 zoospores/ml).

This complex micro biota of rumen helps ruminants to degrade certain mycotoxins and protect them from acute toxic effects of these mycotoxins. However, rumen metabolites of the parent mycotoxin may be equally or more toxic and also contribute to chronic clinical manifestations due to long term consumption of mycotoxins at very low levels. In general mycotoxins pose their negative effects in dairy animals by following means: 1. Poor feed intake or feed refusal 2. Reduced nutrient absorption and impaired metabolism 3. Imbalance in the hormonal physiology 4. Immunosuppression and high incidence of infectious diseases 5. Imbalance of the microbial ecosystem of rumen

Impact of mycotoxins in dairy animals is diversified in nature and in field conditions it becomes very difficult to recognize the negative impact of mycotoxins in productive and reproductive efficiency of farm animals. The clinical signs and symptoms of mycotoxicosis in farm animals are often non specific and confusing and due to the onset of opportunistic diseases the clinical diagnosis becomes very difficult or sometimes impossible. In general the clinical symptoms include suboptimal production, reduced feed intake, intermittent diarrhea, rough hair coat, reduced reproductive efficiency, irregular estrous cycles, early embryonic death and decreased conception rates. Immunosuppression is a major consequence of chronic mycotoxicosis in farm animals which results in increased susceptibility to infectious diseases and failure of vaccination and drug therapy.

Important Mycotoxins for Dairy: Forages and concentrate can be contaminated with many species of fungi including Aspergillus, Fusarium and Penicillium. The major mycotoxins for dairy cattle include Aflatoxins, Ochratoxins, Trichothecenes (T2 and DON) and Zearalenone.

Aflatoxins: Aflatoxins are primarily produced by Aspergillus flavus and Aspergillus parasiticus and are highly toxic, mutagenic and carcinogenic compounds. Major forms of aflatoxins include B1, B2, G1 and G2 but Aflatoxin B1 is the most widespread and biologically active form. Because of its carcinogenic potential Aflatoxin B1 has been extensively studied throughout the world. Aflatoxin B1 is generally metabolized into Aflatoxicol and Aflatoxin M1 in rumen and it is secreted in the milk in the form of Aflatoxin M1. According to the limits of FDA the level of AFB1 should be less than 20 ppb in the feed of lactating cows and 0.5 ppb in milk.

Although no level of aflatoxin can be considered safe for farm animals, the degree of toxicity is related to toxin level, duration of feeding and intensity of other stresses affecting the animals. Symptoms of acute aflatoxicosis include loss of appetite, ataxia, lethargy, rough hair coat and enlarged pale fatty liver. In chronic cases of aflatoxicosis reduced feed efficiency and milk production is evident with reduced resistance to infectious diseases and poor response to vaccination and drug therapy.

Ochratoxins: Ochratoxin is primarily produced by Aspergillus ochraceus and Penicillium verrocosum and occur in wide variety of feedstuffs. Ochratoxin A has been reported to affect dairy cattle but at very high levels as it is rapidly metabolized in the rumen. Young calves are more sensitive to Ochratoxin A toxicity with prolonged exposure. In mature animals the primary toxic effect is the alteration in protein synthesis and few signs of hepatic toxicity. Feeding of mouldy hay with high levels of Ochratoxin A may results in abortion and death of dairy cattle.

Trichothecenes (T2 and DON): Trichothecenes are generally produced by several species of Fusarium and main trichothecenes encountered in ruminant feeds belong to group A (T2 toxin) or group B (DON or Vomitoxin). T2 toxin has been associated with gastroenteritis, intestinal hemorrhages and death. Field observations suggest that T2 toxin is a severe gastrointestinal irritant which can cause hemorrhages and necrosis of intestinal tract. Exposure of dairy cattle to T2 toxin may cause bloody diarrhea, decreased feed intake, poor milk production and absence of estrous cycles. T2 induced immunosuppression in dairy cows is mainly due to alteration in the protein synthesis. DON is commonly referred to as Vomitoxin. In cattle DON has been associated with reduced feed intake and lowered milk production. The trichothecenes are generally immunosuppressive and may be more toxic in animals with low levels of immunity.

Zearalenone: Zearalenone is primarily produced by Fusarium graminearum and several other species of Fusarium. Zearalenone is a natural contaminant of corn and wheat but it may also be present in other feedstuffs. Zearalenone has a close similarity with estrogen regarding its chemical structure and may cause estrogenic effect in animals. Zearalenone is degraded by rumen microbes to alpha-zearalenol which has been considered four times more estrogenic than parent toxin. The primary effects of Zearalenone are reproductive problems which include decrease in embryo survival, edema and hypertrophy of genitalia in pre-pubertal females, decrease in amount of luteinizing hormone (LH) and progesterone produced affecting the morphology of uterine tissues, feminization of young males due to decreased testosterone production and infertility. Other clinical manifestations include vaginitis, vaginal secretions, abortions, infertility and mammary gland enlargement of virgin heifers.

Prevention and Control of Mycotoxins: Mycotoxins are quiet diversified molecules and are produced by various fungi at certain stages of their life cycle. In a feedstuff if a particular mould is visibly present it does not indicate the presence of typical mycotoxin and in contrast if a feedstuff is visibly free from any mould it does not indicate that mycotoxins are absolutely absent. Moreover the mycotoxins are quiet resistant molecules and do not respond to any thermal or chemical treatment which is capable of destroying certain moulds. So in practical field conditions the control of mycotoxins is very critical and should be accomplished in two stages. First stage is the elimination of visible moulds growth in a particular feedstuff and second stage is the detoxification of that feedstuff form any existing mycotoxin. Various strategies are being used in field for the prevention and control of adverse effects of mycotoxins which include chemical detoxification, nutritional strategies, application of mineral clays and use of yeast cell wall based adsorbents in feedstuffs and compound feeds.

The most effective and practical method for the deactivation of mycotoxins so far is the use the inert adsorbents in diets of animals to stop the absorption of mycotoxins from the intestine. An ideal toxin binder should have some properties which are as follows:

1. Ability to bind to a broad spectrum of mycotoxins

2. Ability to mix uniformly in the finished feed

3. Ability to show effectiveness at very low inclusion rates

4. Ability to tolerate high temperature during pelleting process

5. Ability to remain stable at a wide range of pH in gastrointestinal tract

6. Ability to show no affinity for vitamins, minerals and other nutrients of feed

NOVUS Solution: Novus International is an animal nutrition and health company serving the animal agriculture industry for last 50 years through its innovative and research based solutions and programs particularly designed to meet the needs and challenges of its customers all over the world. To control the adverse effects of mycotoxins in feedstuffs and compound feed Novus has a very unique approach.

The solution is based on the use of Toxiban Max in feed to control the negative effects of mycotoxins and to improve the overall health status of farm animals. Quality Toxin Binder – Toxiban Max: For the prevention and control of adverse effects of mycotoxins in dairy animals an innovative and research based mycotoxin binder “Toxiban Max” is now available all over the Pakistan and to assure the supply of this quality product at door step of dairy farmers in Pakistan “Marush International” is serving as sole distributor of “Novus International” and sales and technical team of company is just available to serve its customers in the depth and breadth of country.

Toxiban Max – Product Specifications: Toxiban Max is a proprietary blend and its composition is as follows:

Bentonite Montmorillionite: Bentonite is mineral clay and belongs to Phylosilicate Group and chemically it is called as 2:1 Phylosilicate because in its chemical structure it has two tetrahedral sheets and one octahedral sheet. Due to its unique chemical structure naturally its surface area is very wide but the Bentonite present in Toxiban Max is unique in this regard that it has been processed further by using a specific atomic and molecular technology and its surface area has been increased 5 to 10 times more and one gram of this Bentonite contains 300 meter square active surface area. Due to this molecular technology the each particle of Bentonite is a plate like structure and average size of each particle is less than 1 μm.

These particles carry a negative charge and due to large surface area net negative charge is very high and has maximum affinity for a variety of mycotoxins which carry positive charge naturally. In scientific terms this affinity is called as Cation Exchange Capacity and in Toxiban Max it is 80-100 meq/100 gram.

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Sodium Hydroxide Dry Yeast Cell Wall:  This second most important component of Toxiban Max is obtained from common yeast named as Saccharomyces Cerevisae and its cell wall is rich in Mannooligosaccharides (MOS). MOS is composed of two basic units such as Mannans and Glucans and in the presence of sodium hydroxide both these components get separated and work individually. The Beta Glucan component of MOS has ability to bind mycotoxins due to its typical chemical composition and the resultant molecule becomes inactive with no further ability to pose toxic effect. Moreover due to its carbohydrate and protein nature MOS also acts as a growth promoter for animals.

Lecithin Diatomaceous Earth: The third component of Toxiban Max is a vegetal origin fatty acid named as Lecithin which is an antioxidant by nature. In Toxiban Max Lecithin has been combined with Purified Diatomaceous Earth in a way that its antioxidant property has been increased manifold. Lecithin gets absorbed in blood from intestine and due to its typical chemical structure it undergoes a typical chemical reaction with any mycotoxin present in blood and changes the chemical composition of that mycotoxin.

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The resultant chemical compound is no more a mycotoxin but it becomes a Toxoid which further neutralizes the other mycotoxins present in the blood circulation. In this way Lecithin performs the function of immune surveillance within blood stream and protects the animal cells from negative effects of mycotoxicosis. By virtue of its chemical nature it also acts as an intracellular antioxidant and maintains the various body functions.

Lutein Carotene Pigment: The fourth most important component of Toxiban Max is Lutein Carotene Pigment which is a typical xanthopyll pigment belongs to Carotene Family. This natural pigment is obtained from a flowering plant named as Mexican Mary Gold or Tagetes Erecta and its medicinal value has been already established since ancient times. By nature Lutein is an antioxidant and prevents the cellular damage within the animal body. In severe mycotoxicosis Lutein helps the animal to prevent the damage of liver and kidney cells and protects these cells from adverse effects of mycotoxins and also helps to regenerate the dead and damaged cells. Toxiban Max – Prevention and Treatment at One Step: Sodium Hydroxide Dry Yeast Cell Wall and Bentonite Montmorrillionite: Active and passive binding of mycotoxins stops the absorption of mycotoxins from intestine Lecithin Diatomaceous Earth: Lecithin converts toxins into toxoids and provoke immunity against mycotoxins Lutein Carotene Pigment: Lutein prevents the cellular damage and helps regenerate the dead cells due to mycotoxins

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Feeding Recommendations: Finished Feeds: 0.5 to 1 KG per Ton of Finished Feeds Total Mixed Ration (TMR): 0.5 to 1 KG per Ton of TMR on Dry Matter Basis Individual Animal Dosage: 10-15 Grams per Animal per Day- courtesy slide share

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