0～4周龄合浦肉鹅饲粮中赖氨酸、蛋氨酸和苏氨酸适宜水平的研究

本试验选取1日龄健康的合浦雏鹅270只,随机分成9组,每组3个重复,每个重复10只,公母鹅各一半,采用3×3三因素正交试验设计,来确定0～4周龄肉仔鹅赖氨酸、蛋氨酸和苏氨酸的需要量。日粮中赖氨酸、蛋氨酸和苏氨酸含量分别为：赖氨酸各个水平为：0．85％、1．00％、1．15％;蛋氨酸各个水平为：0．35％、0．45％、0．55％;苏氨酸各个水平为：0．55％、0．65％、0．75％。实验结果表明,不同的赖氨酸、蛋氨酸和苏氨酸水平,对鹅的生长性能和血清生化指标有显著影响（P〈0．05）。以增重和料重比为衡量指标,当日粮中赖氨酸含量为1．00％、蛋氨酸含量为0．45％、苏氨酸含量为0．55％时,合浦肉仔鹅生长性能最佳。     

日粮不同蛋氨酸、赖氨酸水平对0～6周龄五龙鹅生长性能的影响

选择1日龄健康五龙鹅雏540只,随机分成9组,每组4个重复,每重复15只,公母各半.采用3×3二因子试验设计.饲粮中蛋氨酸、赖氨酸添加水平均为0.0%,0.1%和0.2%三个水平,饲粮中蛋氨酸实际含量为0.37%、0.47%和0.57%,赖氨酸含量为1.03%、1.13%和1.23%.试验结果表明,当饲粮中蛋氨酸含量为0.57%,赖氨酸含量为1.13%时,鹅的生长性能和饲料利用率最好.     

饲粮蛋氨酸对1～21日龄狮头鹅生长性能的影响

本试验研究了不同蛋白质水平饲粮对1—21日龄狮头鹅的影响,试验选取1日龄健康狮头雏鹅1224只,随机分为6个处理,每处理6个重复,每个重复34只,每处理公母各3栏。试验饲粮设6个蛋氨酸梯度水平,分别为（1．28％、0．38％、0．48％、0．58％、0．68％、0．78％,研究对1—21日龄狮头鹅生长性能、血清生化指标的影响,以确定育雏期狮头鹅饲粮中蛋氨酸的适宜含量。试验结果表明：饲粮蛋氨酸水平对0-21日龄狮头鹅日增重和日采食量无显著差异（P〉0.05）,对狮头鹅耗料增重比有显著影响（P〈0．05）,0．28％和0．78％水平的耗料增重比显著高于其余4组,以0．48％组最小。     

日粮不同氨基酸水平对0~4周龄四川白鹅生长性能和血清生化指标的影响

为了研究日粮中赖氨酸、苏氨酸、色氨酸添加量对鹅生长性能和血清生化指标的影响,试验采用9处理3因素正交试验设计L9(34),将324只1日龄四川白鹅随机分为9组,对0~4周龄四川白鹅日粮中的赖氨酸、苏氨酸、色氨酸需要量进行研究。结果表明:3种氨基酸中仅苏氨酸对日增重、日采食量有显著影响(P0.05),赖氨酸和色氨酸对日增重、料重比无显著影响(P0.05);3种氨基酸对血液生化指标均无显著影响(P0.05);3种氨基酸交互作用对日增重、日采食量及血液生化指标均有显著影响(P0.05);0~4周龄四川白鹅日粮赖氨酸、苏氨酸、色氨酸适宜水平分别为1.15%、0.22%、0.67%。     

鹅日粮氨基酸平衡对其营养成分表观代谢率的影响

试验选取7周龄健康的合浦雏鹅54只,分成9组,每组3个重复,每个重复2只.采用3×3三因素正交试验设计.实验结果表明,当日粮中赖氨酸含量为0.88%,蛋氨酸含量为0.40%,苏氨酸含量为0.44%时,合浦鹅对其日粮中粗蛋白质和氨基酸代谢率最高.     

赖氨酸和其他必需氨基酸对1～18日龄中速型黄羽肉鸡屠宰性能、肉品质和屠体外观的影响

本试验旨在研究赖氨酸和其他必需氨基酸对1～18日龄黄羽肉鸡屠宰性能、肉品质和屠体外观的影响.选取810 只1 日龄健康雄性肉鸡,随机分为9 组,每组6 个重复,每个重复15只鸡.试验设置3个赖氨酸水平(0.89%、1.05%、1.20%)和3个其他必需氨基酸(蛋氨酸+苏氨酸+色氨酸)水平(低水平:0. 66%蛋氨酸+0...     

南方冬春季节洋二元杂种初产母猪哺乳期对颗粒饲料赖氨酸需要量的探究

试验旨在探索饲粮不同赖氨酸水平下添加适宜的合成晶体氨基酸（L-赖氨酸、L-缬氨酸、蛋氨酸、苏氨酸及色氨酸）对冬春季洋二元杂种初产母猪哺乳期生产性能的影响。选择100头长白X约克杂交初产母猪随机分成5个赖氨酸水平组（1．35％、1．25％、1．15％、1．05％、0．95％），但饲粮的净能均为9．68MJ，／kg，并且均在日粮中添加合成赖氨酸1．7kgl／t使其各组日粮的氨基酸比例一致（各组日粮中额外添加合成的蛋氨酸、苏氨酸、色氨酸、缬氨酸，赖氨酸与蛋＋胱氨酸、苏氨酸、缬氨酸、色氨酸、异亮氨酸的比例均为100：60：75：85：19．5：65，饲粮均制粒为4．0颗粒），每组20个重复，每个重复1头，饲养到35日龄断奶。研究结果表明使用赖氨酸1．35％水平组的仔猪断奶窝重和窝增重显著高于其他4组（P〈0．05）。蛋白质水平对母猪日采食量、背膘损失及断奶后发‘睛间隔影响不显著（P〉0．05）。由结果可知．冬春季低温环境下（平均温度为15℃），洋二元杂种初产母猪哺乳期饲粮添加合成L-赖氨酸1．7kg／t和适宜L-苏氨酸、L-缬氨酸、DL-蛋氨酸、L-色氨酸饲喂粗蛋白质为21．85％（赖氨酸1．35％）颗粒饲料时洋二元杂种经产母猪哺乳期生产性能最佳。     

固始白鹅利用现状与发展探讨

固始白鹅原产于河南省固始县及周边地区，体躯羽毛纯白色（个别个体在头部或颈部上段有深褐色小斑块）、在中型地方优良鹅种当中属于体型中等略大的类型，体格细致紧凑。该鹅具有早期生长快，耐粗饲，耗料少，肉质好，而羽绒品质优等特点，是我国少有的肉绒兼用型良种。在一般粗放饲养条件下，30日龄仔鹅体重可达1．5kg以上，60日龄达3．0～3．5k只，90日龄达4．5kg左右（固始白鹅的适宜上市日龄一般为75～90日龄），120日龄即为成鹅，体重一般在5．0。8．5kg之问。在放牧饲养条件下，8月龄屠宰，半净膛和全净膛率分别为79．0％和72．8％。     

维生素AD对生长期固始白鹅生长性能的影响

本试验旨在研究维生素A、D对生长期固始白鹅生长的影响。试验采用3×3完全随机试验设计,将189只30日龄生长期固始白鹅称重后随机分为9个处理组,每个处理组3个重复,每个重复7只。其中,VA设1500、2500、3500IU/kg3个添加水平;VD设3个添加水平,分别为200、350、500IU/kg,试验期30d。结果表明,日粮VA水平为1500、2500时,生长速度快,VA为3500IU/kg时生长下降;在30～45日龄,生长速度无显著性差异(P<0.05)。46～60日龄,生长速度差异显著(P<0.05);日粮VD水平在200～500IU/kg内对增重无显著性差异(P<0.05)。     

乌骨鸡日粮蛋氨酸、赖氨酸、苏氨酸需要量的研究

单因子试验设计,将1日龄丝毛乌骨鸡雏200只,随机分为10组,每组20只,逐只带翅号,研究0～12周龄乌骨鸡对日粮蛋氨酸、赖氨酸、苏氨酸的营养需要。以乌骨鸡生产性能和经济效益为判断依据,乌骨鸡几种氨基酸营养需要(%)为:0～4周龄蛋氨酸0.32,赖氨酸0.90,苏氨酸0.87;5～8周龄蛋氨酸0.29,赖氨酸0.77,苏氨酸0.78;9～12周龄蛋氨酸0.28,赖氨酸0.76,苏氨酸0.77。     

Serum free thyroxine levels respond inversely to changes in levels of dietary iodine in the domestic cat

Because of a perceived increase in the incidence of toxic multinodular goitres in cats in recent years, we investigated the iodine content of three varieties of commercial canned cat foods and studied the acute effects of 'ingestion of these preparations on urinary iodine excretion and serum free thyroxine levels in young, healthy cats. Ten castrated male cats were fed from a common source. The type of food was changed every 2 weeks. Urine and blood specimens were obtained weekly. Serum free thyroxine levels were determined and iodine concentrations in urine were assayed. The iodine content of the cats' food was also assayed. Food varieties of high, intermediate and low iodine content were fed for 2-week periods. There was a consistent, reciprocal relationship between the mean urinary iodine concentration and the mean serum free thyroxine level for each 2-week period. The difference in the mean serum free thyroxine concentrations for the high and low iodine intake periods was highly significant (p<0.01). When the serum free thyroxine level and the urinary iodine level for each cat at each collection throughout the 12-week study were analysed (66 paired results), a strong inverse correlation (r=0.59, p<0.01) was found. We concluded that the serum free thyroxine level in cats, as measured by a kit designed for human serum, is acutely responsive to changes in iodine intake.     

The influence of dietary selenium levels on blood levels of selenium and glutathione peroxidase activity in the horse

Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-Px activities were determined from all blood samples. Selenium concentrations in plasma and whole blood increased linearly from wk 1 to wk 5 and 6, respectively, in Se-supplemented horses. After these times, no significant changes in Se concentration were observed in Se-supplemented or in unsupplemented horses throughout the remainder of the 12-wk trial. Plasma Se reached plateaus of .10 to .11, .12 to .14, and .13 to .14 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Whole blood Se reached plateaus of .16 to .18, .19 to .21, and .17 to .18 micrograms/ml in horses supplemented with .05, .10 and .20 ppm Se, respectively. Plasma SeGSH-Px activity was not significantly affected by dietary treatment. Therefore, this enzyme was not a good indicator of dietary Se in these mature horses.     

The effect of free amino acid levels in the blood and milk of cows on protein levels in milk

In the cows of the whole group under study, a significant negative relation (r = = -0.4797) was found between the histidine level in arterial blood and protein content in milk; further, there was a significant positive relation (r = 0.4624) between alanine level in milk and protein content in milk, and a significant negative relation (r = -0.5028) for the level of threonine. The group of cows with a higher milk output showed a significant negative relation between methionine level in milk and protein content in milk (r = -0.7482) and a highly significant negative relation between threonine level and protein content in milk (r = -0.8410). The negative relations of some amino acids to the content of protein in milk suggest that there is a poor supply of these amino acids for the production of protein in milk.     

Ascorbic acid levels in the bronchopneumonia of calves]

The level of ascorbic acid in the blood plasma of 59 calves was determined. The age of the calves ranged between two and three months and the samples of blood were collected in January. The first group of calves included 30 animals displaying no clinical symptoms of disease: the average ascorbic acid level was 0.50 +/- 0.18 mg per 100 ml. In the second group, consisting of 19 calves, the blood of the animals was collected three weeks after the termination of the acute stage of bronchopneumonia; the average value of ascorbic acid was 0.30 +/- 0.14 mg per 100 ml. The lowest average value of ascorbic acid was obtained in the calves at an acute stage of bronchopneumonia, reaching 0.18 +/- 0.11 mg per 100 ml. The differences of results between groups I and II and between groups I and III were found to be statistically significant. A conspicuous drop of ascorbic acid level was ascertained in calves suffering from bronchopneumonia-this problem needs deeper scrutiny, owing to the fact that bronchopneumonia is responsible for considerable economic losses in large-capacity calf houses.     

Ketoconazole increases the plasma levels of ivermectin in sheep

The parasiticide ivermectin and the antifungal drug ketoconazole are drugs that interact with P-glycoprotein. We have tested the ability of ketoconazole at a clinical dose to modify the pharmacokinetics of ivermectin in sheep. Lacaune lambs were administered with a single oral dose of ivermectin alone at 0.2mg/kg (n=5) or in combination with a daily oral dose of ketoconazole (10mg/kg) given for 3 days before and 2 days after the ivermectin (n=5). The plasma kinetics of ivermectin and its metabolite were followed over 15 days by HPLC analysis. Co-administration of ketoconazole induced higher plasma concentrations of ivermectin, leading to a substantial increase in the overall exposure of the animals to the drug. Ketoconazole did not reduce the production of the main ivermectin metabolite but it may rather act by inhibiting P-glycoprotein, and thus increasing the absorption of ivermectin. The use of a P-gp reversing agent such as ketoconazole could be useful tool to optimize antiparasitic therapy in the face of the worldwide development of anthelmintic resistance.