| Displacement of abomasum (DA) is a common disease in dairy herds, its cause and pathogenesis are still remain unclear. Many scholars considered that feeding a large amounts of concentrate postpartum will increase risk of development of DA. VFAs (Volatile fatty acids, VFAs) produced by fermenting concentrate in the rumen can inhibit the activity of abomasum, lead to DA finally, which is considered to be the pathological basis. To investigate the effect of butyrate on the development of DA, goats were elected as experimental animals in our study, butyrate of different concentrations were infused into rumen. Blood routine indexes and blood biochemical indexes as well as mRNA expression of M2 and M3 receptors in abomasum tissue were tested.Twelve adult goats were randomly divided into four groups, namely control group, low dose group, middle dose group and high dose group. The goats of three experimental groups were infused butyrate daily at a concentration of 0.5 g/kg,1.0 g/kg and 1.2 g/kg respectively, while goats of control group were infused the same volume saline. Blood and rumen fluid samples were collected daily. Blood routine indexes, blood biochemical, pH and VFA concentration of rumen fluid were tested. Abomasum tissues were collected a week after infusion. The abomasum tissues structure were observed with HE stain. The mRNA expression of M2 and M3 receptors were checked by qPCR. Results are as follows:1. Rumen pH decreased to different degrees after butyrate infusion, which depend on the dose of infused butyrate. Compared to control group, there were no significant difference in low dose group, while the middle and high dose group significantly decreased(P<0.05) at the 1,2,3, 5,6, and 7 day after infusion. The concentration of butyrate in rumen increased at 4h after butyrate infusion. Compared to control group, the low dose group showed no significant changes. The middle and high dose groups significantly increase(P<0.05 or P<0.01).2. The blood routine indexes and blood biochemical indexes showed no significant difference 1-7 d after butyrate infusion; The observation of HE stain showed that abomasum mucosa epithelium was morphological integrity, glands were ranged well and no significant pathological changes were observed after a week of continuous butyrate infusion.3.The expression of M2 and M3 were detected in abomasum. The expression of M3 is higher than M2 Compared to control group, the M2 expression of low dose group in abomasum mucosa and full-thickness tissue was significantly elevated (P<0.05 or P<0.01), while there were downward trend with increased butyrate dose,but the difference was not significant. The M3 expression of low dose group in abomasum mucosa increased, but the difference was not significant, whereas there was significant increase in abomasum full-thickness tissue (P<0.01). The M3 expression of middle and high groups decreased with increased butyrate dose. There were significant difference in full-thickness tissue of middle and high dose group as well as in mucosa of high dose group (P<0.05).In conclusion, butyrate didn’t cause abomasum mucosa damage, liver and kidney injury, systemic inflammation. While high concentration of butyrate inhibited the expression of cholinergic receptors, result in a decreased sensitivity to acetylcholine, subsequently lead to decreased abomasal motility. |
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