Study On The Etiological Factors And Clinicopathology Of Left Displaced Abomasum Of Dairy Cows

Left displaced abomasum (LDA) is one of the most frequent diseases of perinatal period in dairy cattles, mainly occurring in high milk yield postpartum dairy cows. With the rapid growth of breeding scale, especially after the melamine milk incident, scattered raising dairy cattles were centralized to enter the specialized raising districts, so the management and the environment changed a lot. Although the milk yield improved, the incidence of LDA also significantly increased.Breeding mode had taken place a lot of changes,the milk production raising, however,the incidence of LDA has significantly increased. As the LDA of dairy cows is a multifactorial disease, there is no effective preventive measures at the present. Surgery operation is the common method used in most clinical cases. The economic consequences of LDA are becoming more important due to high costs of treatment, discard milk, reduced milk production and difficult postoperative recovery resulting in culling or even death.A detailed investigation had been conducted for 5 dominance breeding areas in Jidong area,Hebei province.The mainly investigate contents including breeding management, average milk yield,forage composition and resource, feeding system and epidemiology of LDA.The cases of final diagnosis inquiring in detail for parity,milk yield, feed intake,and body condition score. The blood was collected from a jugular veins and serum was separated, biochemical indexes were determined in blood serum. In the last part, the highest correlation degree between all indexes and LDA had been found using gray relational grade analysis. Theory tools to monitor for developing LDA were established.Part 1:Relationship between the development of LDA and dairy cows'feed intake,milk production,body conditions scoreOccurrence of left displaced abomasum was studied in 5 dairy herds with 1962 milking cows located in Jidong area, Hebei province.The main purpose of the study was whether there were relationship in cows of development of LDA and feed intake, milk production, body condition score. The results show that the incidence rate of left displaced abomasum was from 1.6% to 4.61% (mean 1.9%). Feed intake, milk production and body condition score were significantly lower to healthy cows(P<0.01), It was also indicated that feed intake and milk production prior to 4 days of LDA in dairy cows decreased,1～2 days later, feed consumption and milk yield reduced dramatically, about 94% and 15.6% respectively. Dairy cows with milk production of 6500-8000Kg, feed intake of 11～14Kg/d and body condition score of three were liable to have left displaced abomasums. These changes may play an important role in the prediction and diagnosis of left displaced abomasums.Part 2:Relationship between left displaced abomasums dairy cow and some serum biochemical indexes.The objective of this part was to analyze the relationship between left displaced abomasums dairy cow and some serum biochemical indexes.Based on clinical diagnosis of LDA,blood was collected from the jugular vein, Control group was also selected from the dairy barn, age, parity, body condition score and blood were collected. Serum K, Ca, Cl, P, Mg concentration and pH value were determined. The results indicated that LDA dairy cows serum chloride and serum potassium were significantly lower than the control group (P<0.01), respectively, serum sodium,total calcium and pH were significantly lower than that in the control group(P<0.05).It was also indicated that left displaced abomasum cow had lower serum potassium, lower serum chlorinum, lower serum sodium, lower pH value, higher blood phosphorus compared to the control group. These changes can be used as monitoring tools to LDA dairy cows.Part 3 The relationship of occurrence of LDA and serum protein in dairy cowsThe objective of the study was determined the some serum protein index and the enzyme activity of the 32 Left displaced abomasum dairy cow. AST,ALP, GGT, a-HBDH activity in the serum of the LDA dairy cows were significantly higher than that of the control groups(P<0.01); It suggests that LDA dairy cows would have some certain liver damage to some extent.Part 4 The relationship of occurrence of LDA and non-protein nitrogen and nitrogen free organic compound in serumThe goal of this study was to identify changes and correlation between the nonprotein nitrogen and unazotized organic compound and left displaced abomasum dairy cows. The results indicated that serum urea in LDA dairy cows was significantly higher than control group (P<0.01),Glucose was significantly lower than that of the control group (P<0.01); serum triglyceride levels and cholesterol levels were lower than that of the control group (P<0.05). respectively, the results showed that LDA cow's energy was severely insufficient, the protein of tissue was broke down more quickly, liver functions were damaged, Cows must decompose protein sufficiently for high milk yield and maintain energy balance, protein decomposition increased the blood concentration of the non-protein nitrogen, it may cause the damage of the kidney function.Part 5 Gray relational grade analysis of causes and diagnosis of LDA in dairy cowsIn this investigation, the correlation of causes and indexes of LDA in Jidong area was evaluated by gray relational grade analysis. It is shown in the result that the most important factor relating LDA is feed intake, other relevant factors are phosphorus, milk yield, total calcium, ion calcium,magnesium,body condition score, alkaline phosphatase,alanine aminotransferase, aspartate aminotransferase,urea,glucose, triglycerides,albumin,a-hydroxybutyrate dehydrogenase,chlorine,total proteins,γ-glutamyltransferase, cholesterol, potassium,sodium, pH. It indicates that in Jidong area, some import index relevant to LDA should be monitored at regular intervals or at any moment, abnormal changed would be found, thus theoretic rules for prevention and diagnosis of LDA will be provided for the farmers.