2005 - Effects on growth of piglets

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过量饲料氟对仔猪生长的影响及其作用机理的探讨
占秀安
论文标题:过量饲料氟对仔猪生长的影响及其作用机理的探讨
Effects of Excessive Feed Fluorine on Growth of Piglets and Approach to Mechanism of the Effects
http://cdmd.cnki.com.cn/Article/CDMD-10 ... 095423.htm

本课题研究了过量饲料氟对仔猪生长的影响,并从相关组织病理学变化、主要器官代谢酶活力、相关激素的合成与分泌、自由基代谢与抗氧化系统功能、细胞凋亡及其关键酶活力、酶蛋白SOD基因表达、肾细胞培养等方面探讨了机理。 96头“杜长大”仔猪(体重17.17±1.01kg)按饲养试验要求分成4组,每组3个重复,每个重复8头(公母各半),分别饲以添加了0、100、 250、400mg/kg氟(氟化钠)的饲粮(基础日粮含消化能13.22 MJ/kg,粗蛋白17.75%,氟26.18mg/kg,仔猪饲料氟的国家限量标准<100 mg/kg)。预试7天后,进行了为期50天的饲养试验和临床观察。饲养试验结束前一周,每组各选体重相近8头猪(公母各半),以Cr_2O_3为外源指示剂进行了消化试验。饲养试验结束后,每组选8头(公母各半)共32头猪进行屠宰试验、剖检与取样分析。同时,通过体外肾细胞培养,检测氟对肾细胞生长与代谢功能的影响。获得了以下主要结果: 1.饲养试验结果表明:过量饲料氟降低了仔猪的日增重(P<0.05),并使采食量呈减少趋势,其中400mg/kg氟还降低了饲料转化效率 (P<0.05)。同时观察到:与对照组相比,试验组仔猪前期表现食欲减退,不愿活动;后期表现被毛粗乱,皮肤苍白,体形消瘦,出现跛行。 2.消化试验结果揭示:过量饲料氟降低了饲料干物质和粗蛋白的表观消化率(P<0.02),其中250 mg/kg和400mg/kg氟还降低了饲料粗脂肪的表观消化率(P<0.02)。 3.屠宰试验结果表明:250 mg/kg和400mg/kg氟提高了肝重比率(P<0.02),400mg/kg氟提高了心脏重比率(P<0.03)。同时剖检肉眼可见: 试验组仔猪出现氟斑牙:肝脏肿大,局灶性坏死;肾脏肿大,脂肪变性,肾盂积水。 4.组织形态学检测显示:(1)　过量饲料氟显著降低了仔猪十二指肠绒毛高度,而增高了隐窝深度;(2)　试验组仔猪肝细胞与肝血窦排列紊乱,界限不明, 肝细胞变性坏死,肾小球皱缩,肾小囊囊腔增大,肾小管上皮细胞变性坏死、脱落而充塞管腔,甲状腺滤泡体积减小,胶质明显减少,滤泡间质纤维化,滤泡旁细胞增生;(3)　试验组仔猪胰、肝、肾和甲状腺细胞核固缩变形,染色质边集,线粒体肿胀、破裂,基质
Experiments were conducted to study the effects of fluorine on the growth of piglets, and approach to the mechanism of the effects by histopathological changes, main organs metabolism enzymes activities, hormonal synthesis and secretion, free radicals metabolism and antioxidation system function, apoptosis and its key enzymes activities, SOD gene expression and nephrocytes culture.Ninety-six piglets (Duroc × Landrace × Yorkshire) with an average initial body weight of 17.17 ± 1.01 kg were randomly allotted to four groups by weight and sex. Every group included three pens (replicates) of eight pigs each. The groups received the same corn-soybean based diet (DE 13.22MJ/kg , CP 17.75%, Fluorine 26.18 mg/kg) supplemented with 0, 100, 250, 400mg/kg fluorine as sodium fluoride. All piglets were given adequate diets and free access to water. The feeding experiment lasted for fifty days after seven days of adaptation period. Seven days before finishing the feeding trail, eight pigs (sex balanced) were chosen from each group and kept in individual pens for digestion experiment by outside indicator as Cr_2O_3 method. At the end of the feeding trial, eight pigs of each group (sex balanced) were randomly selected based on the similar body weight for slaughter experiment and anatomy observation. Meanwhile, the samples of serum, duodenum, pancreas, liver, kidney and thyroid gland were collected for laboratory analysis. In vitro trial, cultural nephrocytes were used to study the effects of NaF with different concentration grades on cell proliferation and metabolism function. The main results were as follows:1. The results of feeding experiment indicated that excessive fluorine decreased average daily gain (p< 0.05) and average daily feed intake (p > 0.05), also did 400 mg/kg fluorine feed gain ratio (p< 0.05). Meanwhile, it was observed that piglets of fluorine treated groups showed anorexia and reluctant moving at earlier trial period, and disorder hair coat, paleness skin, emaciating figure and claudication at later trial period compared with the control group.2. The results of digestion experiment showed that excessive fluorine reducedapparent digestibility of dry matter and crude protein (p< 0.02), also did 250mg/kg and 400mg/kg fluorine that of ester extract (p< 0.02).3. The results of slaughter experiment indicated that 250mg/kg and 400mg/kg fluorine increased the percentage of liver weight to live weight (p< 0.02), also did 400mg/kg fluorine the percentage of heart weight to live weight (p< 0.03). Meanwhile, it was observed that fluorine treated piglets showed fluorine-spot teeth, swollen and locally necrotic liver, swollen and fat denaturalization kidney and hydronephrosis compared with the control group.4. In fluorine treated piglets, histopathological examination revealed denaturalization and necroses hepatocytes and nephrocytes, crimpling nephric spherules, diminishing thyroid follicles and reducing colloids. Cellular ultrastructure observation of liver, kidney and thyroid revealed crimpling nucleolus and condensation chromatin, swollen and enlarging mitochondria and broken mitochondrial cristaes with rupturing or disintegrating membrane, swollen and anamorphic endoplasm reticulum with falling off ribosome. In addition, duodenum villus height was decreased (p< 0.01) while crypt depth increased (p< 0.01).5. Results from main metabolic organs function examination indicated that excessive fluorine: (1) decreased the total protelytic enzyme, lipase, amylase activities in duodenal content and the total protelytic enzyme, lipase activities in pancreas; (2) reduced SDH activities in mitochondria of hepatocytes; (3) lowered AKP and GPT activities while increased LDH activities in kidney; (4) decreased Na+-K+-ATPase, TPO activities and iodine content in thyroid gland; (5) reduced creatinine, Na+ concentration while elevated GPT activities and urea nitrogen concentration in serum; (6) decreased T4 and FT4 level while improved TSH level in serum.6. Results from free radical metabolism and antioxidation system function examin