<p style="margin-top: 0.1pt; margin-right: 0cm; margin-bottom: 0.1pt; text-align: right;"><a href="index.php?option=com_content&amp;view=article&amp;id=3886:would-you-like-to-comment-on-our-articles&amp;catid=619:topics-feedback&amp;lang=en-GB"><span style="color: #ff0000;"><strong><span id="result_box" class="short_text" lang="en"><span class="hps">Commenter cet </span><span class="hps">article</span></span></strong></span></a></p>
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<td><img src="images-joomla/stories/seasons/kobalamin-molekyl.png" alt="kobalamin molekyl" style="vertical-align: middle;" height="161" width="150" /></td>
<td style="text-align: justify;"><strong><strong>Les vitamines B sont un groupe de 8 vitamines hydrosolubles qui jouent un rôle important dans le métabolisme cellulaire. <span class="hps">Elles ne peuvent pas</span> <span class="hps">être produites par</span> <span class="hps">le</span> <span class="hps">corps lui-même</span>, <span class="hps">mais</span> <span class="hps">peuvent être produites par</span> <span class="hps">des bactéries, des</span> <span class="hps">champignons et des plantes</span>. <span class="hps">Chez le cheval</span>, <span class="hps">les micro-organismes</span> <span class="hps">dans l'intestin</span> <span class="hps">(</span>principalement <span class="hps">le </span><span class="alt-edited">gros intestin) sont</span> <span class="hps">capables de synthétiser</span> <span class="hps">des vitamines B</span> <span class="hps">et les</span> <span class="hps">besoins nutritionnels</span> <span class="hps">ont</span> <span class="hps">seulement</span> <span class="hps">été établis pour</span> <span class="hps">la thiamine</span> <span class="hps">(B1)</span> <span class="hps">et la riboflavine</span> <span class="hps">(B2). Les besoins indiqués dans PC-Horse ne doivent par conséquent n’être regardés que comme une ligne directrice.</span></strong></strong></td>
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<p style="text-align: justify;"><strong>Fonction<br /></strong>La vitamine&nbsp;<span id="result_box" class="" lang="fr"><span class="hps">B12</span> <span class="hps alt-edited">effectue</span> <span class="hps alt-edited">de nombreuses fonctions</span> <span class="hps">dans le corps.</span> <span class="hps alt-edited">C'est</span> <span class="hps">un</span> <span class="hps">composant</span> <span class="hps">de plusieurs</span> <span class="hps alt-edited">systèmes enzymatiques</span><span class="">, dont la plupart</span> <span class="hps">sont concernés par</span> <span class="hps">la synthèse des protéines</span><span class="alt-edited">, le métabolisme des glucides et</span> <span class="hps alt-edited">des lipides</span> <span class="hps alt-edited">et la synthèse</span> <span class="hps">des</span> <span class="hps">bases</span> <span class="hps">puriques et pyrimidiques</span> <span class="hps">qui sont</span> <span class="hps">des éléments essentiels de</span> <span class="hps">l'ADN</span> <span class="hps">et de l'ARN</span><span class="">.</span> <span class="hps alt-edited">Les purines</span> <span class="hps">peuvent également fonctionner</span> <span class="hps">comme des neurotransmetteurs</span>.</span></p>
<p><strong>Sources alimentaires</strong></p>
<p style="text-align: justify;"><span id="result_box" class="" lang="fr"><span class="hps alt-edited">La vitamine</span> <span class="hps">B12</span> <span class="hps">englobe plusieurs</span> <span class="hps">formes chimiques</span> <span class="hps">qui ont toutes</span> <span class="hps alt-edited">une activité similaire de la vitamine</span> <span class="hps">B12</span><span class="hps alt-edited">.</span> <span class="hps">La</span> <span class="hps">forme synthétique</span> <span class="hps">de la vitamine</span> <span class="hps alt-edited">utilisée pour compléter</span> <span class="hps">les aliments</span> <span class="hps">ou</span> <span class="hps alt-edited">pour être</span> <span class="hps">donnée aux animaux</span> <span class="hps">est</span> <span class="hps">le plus souvent</span> <span class="hps alt-edited">la cyanocobalamine</span>. <span class="hps">La quantité de</span> <span class="hps">vitamine</span> <span class="hps">B12</span> <span class="hps">est faible</span> <span class="hps">dans la plupart des</span> <span class="hps alt-edited">céréales</span> <span class="hps">ainsi que </span><span class="hps">dans</span> <span class="hps">la levure de bière</span>. <span class="hps">Cependant,</span> <span class="hps">dans la plupart des</span> <span class="hps alt-edited">fourrages </span><span class="alt-edited">elle est relativement</span> <span class="hps alt-edited">élevée comparativement</span> <span class="hps">aux besoins</span> <span class="hps">de l'animal.</span> <span class="hps">Les valeurs moyennes pour</span> <span class="hps alt-edited">un foin de graminées</span> <span class="hps">sont</span> d'<span class="hps alt-edited">environ 10 µg</span> <span class="hps">par kg de matière</span> <span class="hps">sèche</span> <span class="hps atn">(</span><span class="">ou 0,01</span> <span class="hps">mg</span> <span class="hps">/</span> <span class="hps">kg MS</span>). <span class="hps">La plupart de la</span> <span class="hps">vitamine B12 dans</span> <span class="hps">les foins</span> <span class="hps">provient de</span> <span class="hps">la contamination bactérienne</span> <span class="hps alt-edited">car les plantes</span> <span class="hps">ne peuvent pas synthétiser</span> <span class="hps">la vitamine.</span></span></p>
<p style="text-align: justify;"><span class="hps">Bien que la</span> <span class="hps alt-edited">vitamine B12 ne soit pas</span> <span class="hps alt-edited">synthétisée</span> <span class="hps">par les plantes</span><span class="alt-edited">, elle est produite</span> <span class="hps">par les microbes</span> <span class="hps">dans les intestins.</span> <span class="hps">Pour synthétiser</span> <span class="hps">cette vitamine</span>, <span class="hps">les</span> <span class="hps">microbes</span> <span class="hps">ont besoin de</span> <span class="hps">cobalt.</span> <span class="hps">Il</span> <span class="hps">est donc nécessaire de</span> <span class="hps">veiller à ce que</span> <span class="hps">le cheval</span> <span class="hps alt-edited">reçoive</span> <span class="hps alt-edited">suffisamment de cobalt</span> <span class="hps alt-edited">dans sa ration</span>. <span class="hps alt-edited">Le besoin en</span> <span class="hps alt-edited">cobalt</span> <span class="hps">est fixé à</span> <span class="hps">0,05</span> <span class="hps">mg</span> <span class="hps">par kg de matière</span> <span class="hps">sèche de la ration</span> <span class="hps">pour toutes les catégories</span> <span class="hps">de chevaux</span> <span class="hps">(NRC,</span> <span class="hps">2007)</span></p>
<p style="text-align: justify;"><span id="result_box" class="" lang="fr"><span class="hps alt-edited">Les aliments concentrés</span> <span class="hps">sont souvent</span> <span class="hps alt-edited">complétés par</span> <span class="hps">0,10-0,15</span> <span class="hps">mg</span> <span class="hps atn">(</span><span class="">100-150</span> <span class="hps">µg)</span> <span class="hps alt-edited">de vitamine B12</span> <span class="hps">par kg de matière</span> <span class="hps">sèche</span><span class="">.</span> <span class="hps">Cependant</span>, <span class="hps alt-edited">tous les aliments concentrés</span> <span class="hps">pour les chevaux</span> <span class="hps alt-edited">ne sont pas complétés avec</span> <span class="hps">la vitamine.</span></span></p>
<p><strong>Besoins<br /></strong></p>
<p style="text-align: justify;"><span id="result_box" class="" lang="fr"><span class="hps alt-edited">Sur la base</span> <span class="hps alt-edited">de la littérature</span> <span class="hps alt-edited">et des besoins</span> <span class="hps alt-edited">indiqués pour</span> <span class="hps">les autres animaux domestiques</span>, <span class="hps">PC</span><span class="">-Horse</span> <span class="hps">fournit</span> <span class="hps">les</span> <span class="hps">lignes directrices suivantes pour</span> <span class="hps alt-edited">de vitamine B12</span> <span class="hps">dans les rations</span> <span class="hps">des chevaux</span><span class="">:</span></span></p>
<p style="text-align: justify;"><em><span class="hps">Pour</span> <span class="hps">tous les types de</span> <span class="hps">chevaux adultes</span>: <span class="hps">0,0002</span> <span class="hps atn">mg (</span><span class="">0,2</span> <span class="hps">µg</span><span class="">) par kg</span> <span class="hps">de poids corporel.</span> <span class="hps">Pour les jeunes</span> <span class="hps">chevaux en croissance</span>, <span class="hps">le calcul</span> <span class="hps">se fait selon</span> <span class="hps alt-edited">le</span> <span class="hps alt-edited">poids corporel espéré</span> <span class="hps alt-edited">à l'âge adulte.</span></em></p>
<p style="text-align: justify;"><strong>Carence<br /></strong><span id="result_box" class="" lang="fr"><span class="hps">La vitamine B12</span> <span class="hps">peut être stockée</span> <span class="hps">dans le corps,</span> <span class="hps">principalement</span> <span class="hps">dans le foie.</span> <span class="hps">Les symptômes de carence</span> <span class="hps alt-edited">n'ont pas été rapportés</span> <span class="hps">chez les chevaux</span>.</span></p>
<p style="text-align: justify;"><strong>Toxicité<br /></strong><span id="result_box" class="" lang="fr"><span class="hps">Comme</span> <span class="hps">la vitamine B12</span> <span class="hps">est une vitamine</span> <span class="hps alt-edited">hydrosoluble</span>, l'excès de <span class="hps">consommation</span> <span class="hps">sera</span> <span class="hps">excrété</span> <span class="hps">dans l'urine et</span> <span class="hps">dans la bile</span>. <span class="hps alt-edited">La toxicité de la vitamine B12</span> <span class="hps">chez les chevaux</span> <span class="hps">n'a jamais été rapportée</span><span class="">.</span></span></p>
<p style="text-align: justify;"><strong>PC-Horse<br /></strong>PC-Horse<span class="hps"></span><span class="atn"></span> <span class="hps">calcule</span> <span class="hps">des valeurs indicatives pour</span> <span class="hps">les apports en vitamine B12</span> <span class="hps">individuellement pour</span> <span class="hps">chaque cheval</span>. <span class="hps">Lorsque les valeurs</span> <span class="hps">peuvent être obtenues</span>, la B12 <span class="hps">est incluse dans les</span> <span class="hps">tables d'alimentation</span>. <span class="hps">Lors de la composition</span> <span class="hps">des rations</span> <span class="hps">avec</span> <span class="hps">PC</span><span class="atn">-</span>Cheval, <span class="hps">vous serez toujours</span> <span class="hps">en mesure de contrôler</span> <span class="hps">que la prise de</span> <span class="hps">vitamine B12</span> (et de cobalt) <span class="hps">est</span> <span class="hps">au moins suffisante pour</span> <span class="hps">se conformer aux</span> <span class="hps">lignes directrices proposées</span>. <span id="result_box" class="" lang="fr"><span class="hps">Toutefois</span><span class="">,</span> <span class="hps alt-edited">comme les besoins pour cette</span> <span class="hps">vitamine</span> <span class="hps">n'existent pas</span><span class="">, vous</span> <span class="hps">ne serez pas averti</span> <span class="hps">de toute insuffisance</span> <span class="hps">ou</span> <span class="hps">excès.</span></span></p>
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<p style="margin-top: 0.1pt; margin-right: 0cm; margin-bottom: 0.1pt;"><em>Cet article a été écrit par Dr. Day Austbø.</em><br /> <em>Copyright: PC-Horse International - Norvège 2015</em><br /> <em><span id="result_box" class="" lang="fr"><span class="hps">Sentez-vous</span> <span class="hps">libre d'utiliser et</span> <span class="hps alt-edited">publier cet article</span>. <span class="hps alt-edited">Merci d'</span> <span class="hps">indiquer la</span> <span class="hps">source et l'auteur</span><span class="">.</span></span></em></p>