| The experiment includes two parts. In part 1, the goat models of left abomasal displacement (LAD) were established. In part 2, the established models were used to determine the effects of LAD on physicochemical parameters in goats.Part 1: 15 healthy unpregnant goats were randomly divided into three groups ( 5 goats/group), and were established the models of LAD by operation, abomasum moved to left abdominal cavity and fixed at the horizontal line of the hip joint. Atropine (0.5mg/Kg.BW) was injected twice times at 60min and 30min before operation. In groupâ… , the experiment goats were not starved, but starved for 48h in groupâ…¡before operation. In groupâ…¢, the goats were also hungered in 48h,while their abomasums were heavily filled with air for 30 min before abomasums were displaced to the left abdominal cavity. The results showed that there were no clinical symptoms of LAD in groupâ… and groupâ…¡in 7 days, 15 days, 20 days, and 30 days after the operation. As making exploratory laparotomy on the 30th day, it showed that abomasums were almost empty, with little chymes, but no hydrops, pneumatosis, or gastroatonia. But in groupâ…¢, there were the characteristic'ping'sounds as early as 7 days after the operation while taking auscultation and percussion on the left abdominal wall in goats, and abomasums were obvious hydrops, pneumatosis, and gastroatonia during making exploratory laparotomy.Part 2:15 healthy unpregnant goats were randomly divided into three groups (5 goats/group), all of them were operated on abomasums filled with air for 30 min, and then intubated T type tubes into the abomasums and rumens for collecting gastric juice. The abomasums were fixed on the right abdominal wall in groupâ… ( as the control group), on the bottom of left abdominal cavity in groupâ…¡, and on the left abdominal wall at the horizontal line of the hip joint in groupâ…¢, respectively. Abomasal and ruminal gastric juice as well as blood parameters were daily measured before and after operation. Histopathological changes in samples from the abomasal wall were observed during and on the 18th day after operation. The results showed that volatile fatty acid (VFA) in the rumen of goats with LAD were significantly changed. Ratio of acetic acid and propanoic acid increased, which was higher in groupâ…¢than groupâ…¡(p<0.05), and there was no significant deviation between groupâ… and groupâ…¡. The pH values were decreased in ruminal gastric juice, but not significantly. The secretion of gastrin were obviously decreased , and the content of serum sodium , serum potassium , serum chlorinum decreased significantly in groupâ…¡and/or groupâ…¢. There were obviously decreased in calcium and magnesium in serum in groupâ…¡or groupâ…¢(p<0.05), compared with groupâ… . On 18th day after the displacement of abomasums, there were no obvious histopathological changes in sections under light microscope.From the experiment results, a typical animal model of LAD in healthy goats could not be successfully established only with pulling abomasums to left abdominal cavity by force. The key point of the success of establishing the animal models was the abomasal relaxation induced by the method of heavily filling abomasums with air. The experimental results suggested that the mechanism of LAD from clinical patients might not be due to a simple mechanical pressure on the abomasums, but be related to various factors inducing gastroatonia. During the first stage of moderate abomasal displacement, such as the abomasal displacement on the bottom of the left abdominal cavity, there were significant changes of the VFA in rumen, gastrin or electrolytes in serum, even before the appearance of the first clinical symptom, which were very helpful in an early diagnose and timely treatment of LAD.
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