Cottonseed Meal And Hull Inducing Urolithiasis In Male Xinjiang Fine-wool Sheep And Research To The Mechanism

Sheep husbandry occupies an important position in Xinjiang stockbreeding industry. Xinjiang is China's largest production base of cotton and a large number of cotton by-products used as cattle feed. With a large number of applications of cottonseed meal and cottonseed hull, urolithiasis of male wool sheep becomes endemic, which resulted in significant economic losses. But little is known about the mechanism.The study observed the prevalence situation of urolithiasis by feeding cottonseed meal and cottonseed hull. Furthermore, through three feeding trials, the formation mechanism of sheep urinary calculi was discussed by application of cottonseed meal, cottonseed hull to induce urolithiasis analysis of nutrient content of the cottonseed meal and cottonseed hull, chemical composition of stones, blood and urine biochemical parameters, pathological changes of the urinary system.The main contents include the following seven aspects:first, with the observation of incidence of urolithiasis, we analyzed and the feeding management, pathology, and biochemical parameters; Second, on the basis of the observation, three feeding induced test was designed:1) 36 male fine-wool sheep (4 months old), randomly divided into 3 groups, were fed with cottonseed meal 10%,20% 30% of the diet, respectively. After pre-trial period of 7 days, the trial was conducted 60-day; 2) 36 male fine-wool sheep (4 months old) were randomly divided into 3 groups. The control group was fed daily with basal diet (7% cottonseed meal), test group 1 fed with the basal diet+300g cottonseed hull, test group 2 fed the basal diet+450g cottonseed hull; 3) 48 male fine-wool sheep (4 months old) were randomly divided into 4 groups. The control group was fed the diet without cotton by-products. After pre-trial period of 7 days, the trial period were divided into two phases. The first phase (30 days):Group 1 was the control group (17.5% soybean meal in concentrate), test group 1 (17.5% cottonseed meal in concentrate), test group 2 (17.5% cottonseed meal concentrate+150 g cottonseed hull), test group 3 for the experimental group (17.5% cottonseed meal in concentrate+150 g cottonseed hull+ drinking 70% water of test group 2); the second stage (90 days):the control group (the concentrate without cottonseed meal), test group 1 (400g cottonseed meal+the concentrate without cottonseed meal), test group 2 (400g cottonseed meal+400 g cottonseed hull+the concentrate without cottonseed meal), test group 3 (400g cottonseed meal+400 g cottonseed hull+the concentrate without cottonseed meal+drinking 70% water of test group 2). In above trials, blood, urine and urinary-related indicators were detected and urinary crystal morphology, number and types were observed. Third, biochemical changes of blood and urine in sheep with urolithiasis were detected and crystal morphology of stone was observed. Fourth, urolith was observed by microscope and chemical composition analyzed. Fifth, pathological changes of the urinary system in sheep with urolithiasis were analyzed. Sixth, using mice as animal model, we studied the effect of gossypol on blood parameters and the urinary system injury. Seventh, using cell culture in vitro, the injury mechanism of gossypol on murine renal tubular epithelial cell was discussed.The results show that:1. When male sheep were fed daily containing 800g cottonseed hull+the concentrate containing 12% cottonseed meal in a period of 3 months, the incidence of urolithiasis was up to 37.2%;2. No sheep with urolithiasis was found during 60 days when fed with different levels of cottonseed meal, but urinary crystallization had a increase trend with increase of time and cottonseed meal;3. No sheep with urolithiasis was found during 60 days when fed with different levels of cottonseed hull, but crystallization in urine had a increase tendency with increase of time and cottonseed hull levels;4. During 120-day feeding period, the incidence of urolithiasis in test group 2 was 25% while test group 3 was 16.7% when fed with different levels of cottonseed meal and cottonseed hull.5. In urinary calculi, the contents of phosphorus, potassium, magnesium have the relationship with the corresponding elements in serum. The correlation coefficient were:RP= 0.750 (moderate correlation), RK=0.959 (significant corelated), RMg=0.883 (highly correlated)6. Urolith composition analysis showed that the main component included MgKPO4, MgKPO4·6H2O and Mg2P2O7 (magnesium pyrophosphate). It was firstly found there was Mg2P2O7 in sheep kidney calculi.7. Pathological analysis showed that the kidneys and bladders were seriously damaged and the pathological changes of inflammation was observed in urinary system in sheep with urolithiasis induced fed with cottonseed meal and cottonseed hull;8. Histological results showed that gossypol had toxicity on the kidney of mice, which can cause various degrees of renal interstitial hemorrhage, infarction of renal tubular epithelial cells, granular degeneration and necrosis. So gossypol could cause certain extent of damage on mouse kidney tissue.9. By isolating renal tubular epithelial cells in mice to study the effect of gossypol on the renal tubular epithelial cells, the results indicated that the renal tubular epithelial cell apoptosis induced by gossypol was positively correlated with gossypol concentration and reaction time. With the extension duration of treatment of gossypol, the rate of lactate dehydrogenase (LDH) leakage increased, Na+-K+-ATP enzyme (NKA), and Ca2+-Mg2+-ATP enzyme (CMA) activity was decreased with the gossypol concentration increased.The results suggested that urinary stone caused by high dose of cottonseed meal and cottonseed hull in male fine-wool sheep is a kind of a chronic toxicity of mineral nutrition in metabolic diseases. This study proved that urolithiasis of male fine-wool sheep was mainly caused by feeding with cottonseed meal and cottonseed hull. The main factors of urinary stones were high phosphorus, potassium and magnesium. The analysis of the relationship with the elements of stone composition and the mineral elements of serum indicated that high phosphorus, potassium and magnesium in serum were closely related to urolith formation. Gossypol could cause the damage of kidney tubular and glomerular, the saturation of mineral ions in urine and crystallization, the obstruction of urinary tract and finally information of urinary stones as serum contained high phosphorus, potassium and magnesium.