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<h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Article of the Week - [[Rumination - Anatomy & Physiology|Rumination]]</h2>

<h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Article of the Week - [[Chemical Hazards]]</h2>

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[[Image:Diagram of ruminating contractions.jpg|thumb|right|150px|Diagram of ruminating contractions - Copyright RVC 2008]]

Chemical contamination of foodstuffs can be due to their presence in the environment, or their intentional or unintentional application somewhere along the food chain. Some chemical toxins may occur naturally. Controlling chemicals which are only unintentionally present in the food chain is obviously difficult.  

Rumination is the process of digestion in the ruminant. It involves three simplified processes. the first is regurgitation which increases the surface area of food particles for digestion through further mechanical breakdown. The second is re-[[Mastication|mastication]] and the third reinsalivation. Reinsalivation increases the volume of saliva produced whilst chewing and allows minerals to be recycled.

Foodborne Chemical Hazards may be from the following categories:

==Process==

=Drug Residues=

*Reflex initiated by mechanical stimlation of the receptors in the mucosa of the [[The Reticulum - Anatomy & Physiology|reticulum]], ruminoreticular fold and cardiac area of the [[The Rumen - Anatomy & Physiology|rumen]]

This category consists of:

*Discrete reticular contraction preceedes biphasic ruminal contraction (see [[The Rumen - Anatomy & Physiology#Ruminoreticular contraction|ruminoreticular contractions]])

# '''Veterinary Medicines.'''<br>Veterinary Medicines, after being administered to an animal, will still be present in the animal's tissues (or food products) for a variable ammount of time depending on the drug & the species amongst other things. Drugs given to treat animals intended for food production, if licienced, will have a minimum withdrawal period which must be observed before the animal can go for slaughter (for meat withdrawal).  Withdrawal periods also exist for other animal products, e.g. egg withdrawal, milk withdrawal, etc...This is to allow enough time for the drug to be excreted or metabolised sufficiently so that no drug or only insignificant ammounts will be present in any food derived from that animal.<br> If a Veterinary Medicine is not Licienced for use in a particular species for treating a particular condition then (having observed the [[Cascade System]]) the standard withdrawal period of 7 days for meat & 28 days for milk should be observed. Some drugs are specifically prohibited from use in all food animals (e.g. Phenylbutazone, Lignocaine to name two) and some drugs are prohibited in specific types of food producing animal (e.g. Tilmicosin is prohibited in Dairy cows but not beef cows).<br>Veterianry Medicines whose use are widespread in food producing animals are Antimicrobial & Antiparasitic drugs. Residues of ranquilizers are also of concern.<br>Organic producers ofen have to observe much longer withdrawal periods and can only administer drugs when the use has been specifically approved by a vet. Use of drugs other than to treat sick animals is generally not approved (although welfare should not be compromised).<br><br> 

*Associated with inspiration against a closed glottis creating a negative pressure in the thorax allowing ingesta to be drawn into the [[Oesophagus - Anatomy & Physiology|oesophagus]]

[[Chemical Hazards|Click here to read more]]

 

 

 

 

 

[[Rumination - Anatomy & Physiology|Click here to read more]]

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