<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">L'estomac est</span> <span class="hps">adapté</span> <span class="hps">à</span> <span class="hps atn">une prise d'</span><span>alimentation continue</span><span>, et a un</span> <span class="hps">volume relativement faible</span> <span class="hps atn">(</span><span>15 à 20</span> <span class="hps">litres</span> <span class="hps">pour</span> <span class="hps alt-edited">un cheval</span> <span class="hps alt-edited">de taille moyenne</span><span>, 500</span> <span class="hps alt-edited">kg</span><span>)</span><span>.</span> <span class="hps">L'estomac</span> <span class="hps">peut être subdivisé en</span> <span class="hps">trois parties principales </span><span>:</span></span></p>
<p style="text-align: justify;"><br />1. <span id="result_box" class="short_text" lang="fr"><span class="hps">La partie</span> <span class="hps">de l'œsophage</span> <span class="hps">qui n'a pas de</span> <span class="hps">glandes</span></span><br />2. <span id="result_box" lang="fr"><span class="hps">La partie</span> <span class="hps">fundique</span> <span class="hps">qui</span> <span class="hps">possède des glandes</span> <span class="hps">qui produisent</span> <span class="hps">l'acide chlorhydrique,</span> <span class="hps">des enzymes</span> <span class="hps alt-edited">et du mucus</span></span><br />3. <span id="result_box" lang="fr"><span class="hps">La partie</span> <span class="hps">du pylore</span> <span class="hps alt-edited">qui possède</span> <span class="hps">des glandes</span> <span class="hps alt-edited">productrices de mucus</span></span><br /><br /></p>
<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">La partie</span> <span class="hps">de l'oesophage</span> <span class="hps">de l'estomac</span> <span class="hps">a habituellement</span> <span class="hps">une forte concentration de</span> <span class="hps">microbes</span> <span class="hps">(jusqu'à</span> <span class="hps">1000</span> <span class="hps">millions</span> <span class="hps">par gramme</span>). <span class="hps">Ceux-ci</span> <span class="hps alt-edited">fermentent</span> <span class="hps atn">(</span><span class="alt-edited">décomposent</span>) <span class="hps">les aliments ingérés</span>. <span class="hps">La température élevée</span> <span class="hps">dans l'estomac,</span> <span class="hps">et</span> <span class="hps">les liquides</span> <span class="hps">qui sont mélangés</span> <span class="hps">dans l'alimentation</span> <span class="hps">au cours de</span> <span class="hps">la mastication</span> <span class="hps">ainsi que</span> le <span class="hps">pH</span> <span class="hps">neutre</span> <span class="hps">ou</span> <span class="hps">légèrement</span> <span class="hps">acide,</span> <span class="hps">fournit</span> <span class="hps">un excellent environnement</span> <span class="hps">pour les bactéries.</span> <span class="hps atn">(</span>Cette <span class="hps">partie de l'estomac</span> <span class="hps">est aussi habitée</span> <span class="hps alt-edited">par des</span> <span class="hps alt-edited">larves de mouches </span> <span class="hps atn">(</span><span class="alt-edited">Gasterophilus</span>) <span class="hps">qui</span> <span class="hps alt-edited">vivent et</span> <span class="hps alt-edited">hivernent</span> <span class="hps">dans l'estomac</span> <span class="hps">du cheval</span> . <span class="hps">À maturité</span>, <span class="hps alt-edited">les</span> <span class="hps alt-edited">larves longues </span> <span class="hps">de 1-2</span> <span class="hps">cm</span> <span class="hps alt-edited">sont évacuées</span> <span class="hps alt-edited">avec les matières fécales</span>, <span class="hps alt-edited">se métamorphosent</span> <span class="hps">dans le sol</span> <span class="hps">et émergent</span> <span class="hps alt-edited">en mouches</span> <span class="hps">qui pondent leurs</span> <span class="hps">oeufs</span> <span class="hps">jaunes</span> <span class="hps">sur les</span> <span class="hps">jambes du cheval</span>.)</span></p>
<p style="text-align: justify;">&nbsp;</p>
<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">Cette activité</span> <span class="hps">microbienne</span> <span class="hps">conduit à une</span> <span class="hps">digestion</span> <span class="hps alt-edited">partielle des</span> <span class="hps alt-edited">glucides et des sucres</span>, <span class="hps">et</span> <span class="hps atn">le début de l'</span><span>hydrolyse</span> <span class="hps alt-edited">des</span> <span class="hps">protéines solubles.</span> <span class="hps">La</span> <span class="hps">fermentation</span> <span class="hps">produit de l'acide</span> <span class="hps">lactique</span><span>, les acides gras</span> <span class="hps">à chaîne courte</span>, <span class="hps">et</span> <span class="hps alt-edited">un peu de gaz</span> <span class="hps">de</span> <span class="hps">dioxyde de carbone.</span> <span class="hps alt-edited">Le gaz</span> <span class="hps">est</span> <span class="hps">potentiellement dangereux</span> <span class="hps">parce que le cheval</span> <span class="hps">a une</span> <span class="hps">faible capacité à</span> <span class="hps alt-edited">l'expulser de</span> <span class="hps">l'estomac</span><span>.</span></span></p>
<p style="text-align: justify;"><br /><span id="result_box" lang="fr"><span class="hps alt-edited">La fermentation</span> <span class="hps alt-edited">s'arrête alors que</span> <span class="hps">le contenu gastrique</span> <span class="hps alt-edited">est peu à peu</span> <span class="hps">acidifié</span> <span class="hps">par les sécrétions</span> <span class="hps">fundiques</span> <span class="hps">qui contiennent</span> <span class="hps">la pepsine,</span> <span class="hps">une</span> <span class="hps">enzyme</span> <span class="hps alt-edited">de découpage</span> <span class="hps alt-edited">des protéines</span>, <span class="hps">et de l'acide</span> <span class="hps">chlorhydrique</span> <span class="hps">qui permet de réduire</span> <span class="hps">rapidement</span> <span class="hps">le</span> <span class="hps">pH</span> <span class="hps alt-edited">des aliments</span> <span class="hps alt-edited">ingérés</span> <span class="hps alt-edited">jusqu'</span><span class="hps">entre</span> <span class="hps">2</span> <span class="hps">et</span> <span class="hps alt-edited">3. C'</span><span class="hps">est dans la partie</span> <span class="hps atn">pylorique de l'</span><span>estomac</span> <span class="hps atn">(</span><span>la moitié inférieure</span><span>)</span> <span class="hps">que les</span> <span class="hps">muscles de la paroi</span> <span class="hps">produisent</span> <span class="hps alt-edited">d'abord</span> <span class="hps alt-edited">des contractions</span> <span class="hps">suffisamment solides pour</span> <span class="hps">mélanger</span> <span class="hps">parfaitement le contenu</span>. <span class="hps">Chez les chevaux</span> <span class="hps">nourris</span> <span class="hps alt-edited">de manière peu fréquente</span><span>, les grands</span> <span class="hps">repas</span><span>,</span> <span class="hps">la production de gaz</span> <span class="hps alt-edited">et la sur-</span><span class="hps">distension de l'estomac</span> <span class="hps alt-edited">peuvent devenir un problème</span>. <span class="hps alt-edited">Les chevaux devraient</span> <span class="hps">donc</span> <span class="hps">être nourris</span> <span class="hps alt-edited">avec plusieurs petits repas</span><span>, en particulier</span> <span class="hps alt-edited">lorsqu'ils sont entraînés</span> <span class="hps alt-edited">intensément, et</span> <span class="hps">ont besoin de grandes</span> <span class="hps">quantités d'aliments</span> <span class="hps alt-edited">solides.</span></span><br /><br /><br /><span id="result_box" lang="fr"><span class="hps">Dans</span> <span class="hps alt-edited">l'estomac du</span> <span class="hps">cheval</span><span>, la seule</span> <span class="hps alt-edited">dégradation des</span> <span class="hps">hydrates de carbone,</span> <span class="hps">tels que l'amidon</span><span>,</span> <span class="hps alt-edited">se produit à la suite</span> <span class="hps">de</span> <span class="hps">la fermentation microbienne</span> <span class="hps alt-edited">puisque</span> <span class="hps">l'estomac</span> <span class="hps alt-edited">ne produit aucune</span> <span class="hps alt-edited">enzyme</span> <span class="hps">digérant</span> <span class="hps alt-edited">les hydrates de carbone ou les graisses</span><span>.</span></span></p>
<p style="text-align: justify;">&nbsp;</p>
<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">La sécrétion</span> <span class="hps">d'acide chlorhydrique</span> <span class="hps alt-edited">est régulée par l'</span><span class="hps">hormone gastrine</span> <span class="hps alt-edited">par une</span> <span class="hps">rétroaction</span> <span class="hps">de manière négative</span>. <span class="hps alt-edited">L'augmentation de la sécrétion</span> <span class="hps">de</span> <span class="hps">gastrine</span> <span class="hps">entraîne une augmentation des</span> <span class="hps">concentrations de</span> <span class="hps">HCl</span> <span class="hps">dans l'estomac</span><span>, ce qui</span> <span class="hps">réduit à son tour</span> <span class="hps">la</span> <span class="hps">sécrétion</span> <span class="hps">de</span> <span class="hps">gastrine</span><span>.</span> <span class="hps">La sécrétion de</span> <span class="hps">gastrine</span> <span class="hps">est principalement</span> <span class="hps">stimulée par</span> <span class="hps">la</span> <span class="hps">présence d'aliments dans</span> <span class="hps">l'estomac</span> <span class="hps">par l'intermédiaire</span> <span class="hps">de récepteurs spécifiques</span> <span class="hps alt-edited">dans</span> <span class="hps">paroi de l'estomac</span> <span class="hps">qui réagissent</span> <span class="hps alt-edited">quand la paroi</span> <span class="hps alt-edited">est étirée</span> <span class="hps">et</span> <span class="hps">à des substances</span> <span class="hps">chimiques telles</span> <span class="hps">que des acides aminés</span> <span class="hps alt-edited">de l'alimentation</span><span>.</span> <span class="hps">La partie inférieure</span> <span class="hps">de l'estomac</span> <span class="hps">est la partie</span> <span class="hps">du pylore</span> <span class="hps">où</span> des <span class="hps">glandes</span> <span class="hps">produisent du mucus</span> <span class="hps">qui</span> <span class="hps alt-edited">lubrifie</span> <span class="hps">le</span> <span class="hps alt-edited">digesta</span><span>.</span></span></p>
<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">L'estomac</span> <span class="hps">commence à</span> <span class="hps">vider son contenu</span> <span class="hps">dans l'intestin grêle </span><span>tandis que le</span> <span class="hps">cheval</span> <span class="hps">mange encore</span><span>.</span> <span class="hps">Les contenus stomacaux</span> <span class="hps">avec</span> <span class="hps">un pourcentage</span> <span class="hps">de</span> <span class="hps">matière sèche inférieure à</span> <span class="hps">18</span><span>%</span> <span class="hps">passeront</span> <span class="hps">rapidement,</span> <span class="hps">et peuvent</span> <span class="hps">dépasser</span> <span class="hps">contenu</span> <span class="hps">fibreux</span> <span class="hps">en suivant</span> <span class="hps">la petite</span> <span class="hps">courbure de l'estomac</span> <span class="hps">vers</span> <span class="hps">le pylore</span><span>.</span> <span class="hps">Généralement</span><span>, les régimes alimentaires</span> <span class="hps">riches en fibres</span> <span class="hps">resteront</span> <span class="hps alt-edited">plus longtemps dans l'estomac</span>. <span class="hps">Un mélange adéquat</span> <span class="hps alt-edited">des aliments</span> <span class="hps">avec des</span> <span class="hps">sucs digestifs</span> <span class="hps">est nécessaire</span> <span class="hps alt-edited">pour une digestion</span> <span class="hps">normale</span><span>.</span> <span class="hps alt-edited">La défaillance dans</span> <span class="hps alt-edited">le mélange peut</span> <span class="hps">être causée par </span>:</span></p>
<p style="text-align: justify;">&nbsp;</p>
<p style="text-align: justify;"><span id="result_box" lang="fr"><span class="hps">-</span> <span class="hps">Trop peu de</span> <span class="hps">sécrétions gastriques</span><span>, </span><span class="hps alt-edited">résultant <span id="result_box" lang="fr">souvent </span>de</span> <span class="hps alt-edited">trop de stress physique ou psychologique</span> <span class="hps">rapidement</span> <span class="hps">après le repas.</span><br /> <span class="hps">-</span> <span class="hps">Alimentation</span> <span class="hps">consommée</span> <span class="hps">trop rapidement</span> <span class="hps atn">(</span><span class="alt-edited">le cheval a</span> <span class="hps">trop faim</span>)<br /> <span class="hps">-</span> <span class="hps">A</span><span class="hps">limentation </span><span class="hps alt-edited">donnée en trop grande quantité</span> <span class="hps atn">(</span><span>en</span> <span class="hps">particulier les</span> <span class="hps">concentrés</span> <span class="hps">et les céréales</span><span>)</span><br /> <span class="hps">-</span> <span class="hps">Concentrés</span> <span class="hps">contenant</span> des amidons de blé ou seigle <span class="hps">cuits</span> <span class="hps atn">(</span><span>micronisée</span><span>)</span><span class="hps"></span> <span class="hps">qui peuvent empêcher</span> <span class="hps">l'acide</span> <span class="hps">chlorhydrique</span> <span class="hps">de</span> <span class="hps">réduire</span> <span class="hps">suffisamment</span> <span class="hps">le pH</span> <span class="hps">du contenu gastrique</span> <span class="hps">pour arrêter</span> <span class="hps">la fermentation microbienne</span><span>, entraînant la formation</span> <span class="hps">excessive de gaz</span><span>, la dilatation</span> <span class="hps">de l'estomac</span> <span class="hps">et des coliques</span>.</span><br /><br /></p>