反刍动物饲料营养价值评定及模型应用

反刍动物饲料营养价值评定包括饲料营养成分评定和饲料营养物质可利用性评定两个方面,其中,评定反刍动物饲料营养物质可利用性的方法主要有体内法、半体内法和体外法,因各自的特点分别应用于不同的研究领域.反刍动物饲料营养价值评定模型的应用,又使这些评定方法得到进一步深入和扩展.文章综述了反刍动物饲料营养价值评定的主要方法以及几种营养价值评定模型的应用研究进展.     

反刍动物饲料营养价值评定及替代法展望

传统上评定反刍动物饲料营养价值的方法很多,但多数是评定配合饲料或者粗饲料。现在反刍动物饲料中精料的添加量日益重要,为了追求更高的经济效益有必要对精料的营养价值进行准确评定。近年来,通过消化代谢试验结合替代法评定动物饲料营养价值的报道越来越多,饲料营养价值评定模型的应用,使得一些无法直接评定的肉羊精料的评定方法有了新的方向。文章综述了反刍动物饲料营养价值评定的主要方法以及替代法评定反刍动物精料营养价值和预测模型应用于反刍动物精料原料的可实行性。     

原子吸收光谱法测定饲料中镉测量不确定度的评定

测量不确定度是评定检测样品结果准确度的尺度,本文用原子吸收光谱法对饲料中镉的测量不确定度进行评定,依照JJF1059-1999《测量不确定度评定与表示》的要求,全面了解影响饲料中镉测定的不确定度。研究说明,评定中以A类评定分量占主要地位,评定不给自由度,包含因子统一取2的简化评定过程是可行的。     

适宜的猪饲料评定体系

饲料费用是养猪生产成本中最主要的部分.因此,获得养猪生产的最佳经济效益和最佳状态必须有一个适宜的猪饲料评定体系.这样的一个饲料评定体系既包括对猪营养需要的评定,又包括对饲料组分的有效营养成分的评定.近年来,猪饲料评定体系有了长足发展,特别是在蛋白质和能量评定方面.     

青贮品质评定(一)

正品质评定是对青贮饲料收贮全过程质量优劣的监督,是提高青贮饲料利用效率的重要途径和方法(玉柱和刘长春,2012)。青贮品质评定一般分为感官评定和理化评定。感官评定在青贮饲料现场即可进行,生产实践中比较常用,但这种方法只能表观评定青贮饲料发酵的优劣;对于量化评定青贮饲料的品质以及提高青贮饲料的利用效率,必须借助于理化评定。理化评定一般需要在实验室进行,随着对青贮饲料研究的深入,理化评定也从传统的干物质、pH、有机酸总     

基于决策树算法的奖学金分析应用研究

奖学金评定的质量是当代高校学生最为敏感的问题之一。做到评定的"公平、公正、公开",并更好的鼓励先进,鞭策后进,提高学生全面素质是评定工作的关键。本文基于决策树算法,对高校学生奖学金评定相关属性数据进行分析挖掘。用具体实验发现奖学金评定中的主导因素,为教务人员提供奖学金评定规则制定的支持和帮助。     

青贮饲料的合理调制与质量评定标准分析

本文以非常规型青贮饲料为例,对青贮饲料的调制方法进行分析,并对青贮质量评定标准加以阐述,重点介绍感官评定、PH值评定与实验室评定三项内容,力求通过本文研究,使青贮饲料调制方法更加科学有效,与质量评定标准充分符合,在促进资源高效利用的同时,获得更多的经济效益。     

家禽油脂代谢能值评定方法的研究

油脂是一种重要的家禽高能饲料原料,在整个饲料配方成本中占有很重要的比例,因此,准确评价油脂的代谢能值就显得尤为重要。油脂代谢能值的评定受诸多因素影响,导致油脂代谢能评定结果变异较大,油脂也成为代谢能最难评定的饲料原料之一。本文论述了影响油脂代谢能值评定的因素和评定方法对油脂代谢能测定结果的影响,以期为今后评定家禽油脂代谢能提供参考。     

金工实习成绩的评定与改进

本文介绍了学生金工实习成绩评定的内容,客观、公正、科学地评定学生金工实习成绩的办法。对成绩评定中不科学地方提出改进建议。通过金工实习成绩评定推动金工实习教学质量的提高。     

微卫星DNA与延边黄牛肉用生长性状关系

选择与肉牛主要生产性状紧密连锁的 5个微卫星位点 ,以肉牛线性体型评分方法作为衡量肉牛生长发育的指标 ,运用最小二乘法拟合线性模型 ,分析了延边黄牛肉用生产性状与微卫星标记的关系 ,并分析了微卫星 ETH10和IDVGA4 6位点的不同基因型与肉用生产性状的关系。结果表明 ,微卫星 EHT10位点的等位基因 2 0 9对外貌线性评定中的背线性状、肌肉度线性评定中的肩部性状有正面影响 ,等位基因 2 13对外貌线性评定中的系部、肌肉度线性评定中的尻形状和细致度线性评定中的骨骼及皮肤性状有正面影响 ,而等位基因 2 15对外貌线性评定中的背线性状、肌肉度线性评定中的尻形状有负面影响 ;微卫星 IDVGA4 6位点的等位基因 2 4 9对背线、前肢和后肢等外貌线性评定性状 ,肌肉度线性评定的腰宽以及细致度线性评定的骨骼和皮肤性状有正面影响 ,等位基因 2 0 3对外貌评定性状的头部、背线 ,肌肉度评定性状腰宽以及细致度评定性状骨骼和皮肤有负面影响 ,等位基因 2 4 5对腰宽性状也起到负面影响     

奶牛发情周期中毛 唾液和乳汁孕酮水平的变化

本实验采用放射免疫分析法(RIA)测定了11头奶牛一个发情周期里毛、唾液、乳汁中孕酮(P_4)含量。经产牛(n=8)的毛和唾液中P_4水平变化与乳汁中P_4水平变化一致。青年牛(n=3)的毛和睡液中的P_4水平变化一致,并分别与经产牛毛和唾液中P_4水平变化一致。7头配种后的经产牛和5头配种后的青年牛分别取20和23天的样品进行妊娠诊断,与配种后60天的直检结果相对照,依据经产牛毛、乳P_4水平进行妊娠诊断的阳性准确率分别是85.7％(6/7)和100％(7/7),依据青年牛毛P_4水平进行妊娠诊断的阳性准确率为100％(5/5)。     

Dystocia in beef heifers: A review of genetic and nutritional influences

Breeding beef heifers for the first time at 15 months of age has potential to increase the efficiency of the beef breeding-cow herd. An increased incidence of dystocia in heifers calving at 2 years of age, compared to mature cows, is a major reason many farmers in New Zealand have not adopted the practice. The predominant type of dystocia affecting 2-year-old heifers is feto-maternal disproportion, a condition in which the fetus is too large relative to the size of the heifer's pelvis. Reducing birthweight of the calf is a means of reducing the incidence of dystocia. Birthweight and length of gestation are determined by genotype of the calf, maternal genetic effects and environmental effects.

Bulls with low estimated breeding values for birthweight have been selected for mating heifers; however, the positive genetic correlation between birthweight and mature weight meant that the progeny of these bulls tended to be lighter at finishing, making them less desirable in the beef industry. The genotype of the dam also plays a role in determining the risk of dystocia; the maternal ability of the dam to nurture the fetus influences birth- weight, and the dam's genetic potential for growth influences the size of her pelvic area. Heavy heifers tend to produce high- birthweight calves, counteracting the reduction in the incidence of dystocia resulting from the larger pelvis in larger heifers.

Manipulating feeding level during pregnancy offers an alternative method for manipulating the birthweight of calves. Little is known about the effects of nutrition in early gestation on placental development or birthweight of calves. No differences in the birthweight of calves have been observed in response to variation in feeding in mid-pregnancy, and variable responses in birthweight and the incidence of dystocia to feeding in the third trimester of pregnancy have been reported. Differences in birthweight have not always resulted in differences in the incidence of dystocia, primarily due to differences in liveweight of the heifer also induced by feeding regimens. Variability in the incidence of dystocia in response to feeding level in the third trimester of pregnancy makes it difficult to make recommendations for the feeding of heifers at this stage of gestation. More research is needed into the effects of nutrition in early gestation on fetal and placental development in cattle.     

Obituary-Roger Brereton Marshall

Roger Marshall was born in Christchurch on 27 May 1933 and died at his home in Palmerston North on 24 October 2001. He graduated BVSc from the University of Sydney in 1958 and began his professional career in clinical veterinary practice in Morrinsville. Wishing to specialise in veterinary microbiology, he later enrolled in the postgraduate course for the Diploma in Microbiology at the University of Otago under Professor JAR Miles. On gaining the Diploma in 1963, Roger was appointed a foundation lecturer in veterinary microbiology in the newly formed Faculty of Veterinary Science at Massey University.     

Assessment of changes in blood volume in response to resuscitative fluid administration in dogs

Objective: To determine the continuous changes in blood volume in response to fluid administration using an in‐line hematocrit monitor. Design: Prospective study. Setting: Research laboratory. Animals: Four healthy dogs. Interventions: Each dog received intravenous boluses of 80 mL/kg of 0.9% saline (S), 4 mL/kg of 7.5% saline (HS), 20 mL/kg of dextran 70 (D), 20 mL/kg of hetastarch (HES), or no fluids (control, C) on separate occasions. Fluids were administered at 150 mL/min in the S, D, and HES groups, and at 1 mL/kg/min in the HS group. Measurements and main results: Blood volume changes were measured every 20 seconds for 240 minutes using an in‐line hematocrit monitor. There was a rapid rise in blood volume during all infusions. Immediately after the administration of crystalloid fluids, the rapid rise in blood volume ceased. Subsequently, there was a steep decline in blood volume for 10 minutes, and a slower decline thereafter. In contrast, the rise in blood volume continued for at least 10 minutes after the infusion of the colloids was complete, and a plateau was observed for the remainder of the experiment. The blood volume effect, as measured by area under the curve, was significantly greater in the saline group than the other groups during the infusion time and for the 0–240 minutes time period. The areas under the curve for the two colloid solutions were not significantly different from each other during any time periods. The percent increase in blood volume immediately following the infusions was 76.4±10.0 in the S group, 17.1±3.2 in the HS group, 23.0±10.5 in the D group, and 27.2±6.4 in the HES group. At 30 minutes from the start of the infusion, the mean percent increases in blood volumes were 35.2±9.3 in the S group, 12.3±0.9 in the HS group, 35.9±7.3 in the D group, and 36.8±6.5 in the HES group. At 240 h post‐infusion, the mean percent increases in blood volume were 18.0±9.7 in the S group, 2.9±6.1 in the HS group, 25.6±16.1 in the D group, and 26.6±8.6 in the HES group. The C group had a mean percent change in blood volume of ?3.7±3.4 at the end of the experiment. Conclusions: This study indicates that the rapid administration of saline at clinically relevant doses leads to the largest immediate increase in blood volume, although this change is transient because of rapid redistribution of the fluid. Despite a brief increase in blood volume that was almost 3 times the volume administered, hypertonic saline led to the smallest increase in blood volume post‐infusion. The synthetic colloid solutions increased the blood volume by an amount greater than that infused and the effect was sustained for a longer period of time than seen following crystalloid administration, but the maximum increase in blood volume was significantly less than saline. The measurement of continuous changes in blood volume, using an in‐line hematocrit monitor, was a useful means of assessing the dynamic effects of fluid administration in dogs in a research setting.     

玉米赤霉烯酮对后备母猪子宫和卵巢抗氧化和炎症指标及相关基因表达的影响

试验旨在研究玉米赤霉烯酮（zearalenone,ZEA）对后备母猪子宫和卵巢抗氧化和炎症指标及相关基因表达的影响。选择胎次和体重（（23.20±0.68）kg）相近的长×大二元后备母猪48头,随机分为4组,每组设12个重复,每个重复1头母猪。对照组（CON组）饲喂基础饲粮,试验组（T1、T2、T3组）饲喂在基础饲粮中分别添加200、800、1600 μg·kg^-1ZEA的试验饲粮。预试期7 d,正试期40 d。结果如下：1）与CON组相比,T3组血清T-AOC和SOD活性显著降低（P<0.05）,MDA水平显著升高（P<0.05）。2）与CON组相比,子宫组织中,T2和T3组T-AOC活性显著降低（P<0.05）,T3组SOD活性极显著降低（P<0.01）,卵巢组织中,T3组T-AOC活性、T2组GSH-Px和SOD活性显著降低（P<0.05）,T3组MDA水平显著升高（P<0.05）。3）与CON组相比,T2组血清TNF-α和IL-4水平显著升高（P<0.05）,T1~T3组血清IL-10水平显著降低（P<0.05）。4）与CON组相比,子宫组织中,T2组IL-1β水平显著升高（P<0.05）,T1和T3组IL-10水平显著降低（P<0.05）。卵巢组织中,T2组TNF-α水平显著升高（P<0.05）,T1~T3组IL-4水平显著升高（P<0.05）。5）子宫组织中,T3组Cu/Zn-SOD mRNA的相对表达显著低于CON组（P<0.05）,T2组IL-1β mRNA的相对表达显著高于CON组（P<0.05）。6）卵巢组织中,T3组GSH-Px mRNA的相对表达显著低于CON组（P<0.05）,T2组IL-1β mRNA的相对表达显著高于CON组（P<0.05）。综上所述,ZEA能通过抑制SOD和GSH-Px的表达与合成,降低后备母猪子宫和卵巢的抗氧化性能,并引起氧化应激。ZEA能通过促进TNF-α和IL-1β表达与合成引起子宫和卵巢的炎症反应,抑制IL-10的表达与合成从而抑制两组织的抗炎反应。     

Copper deficiency in sheep: An assessment of the relationship between concentrations of copper in serum and plasma

AIM: To assess the relationship between concentrations of copper in serum and plasma in sheep.

METHODS: Concentrations of Cu were measured in paired serum and heparinised plasma samples collected from 110 sheep in nine flocks. Linear regression was used to evaluate whether flock or gender had a significant effect on the association between concentrations of Cu in serum and plasma. The individual results for concentrations of Cu in serum were then compared with those from plasma, using correlation and limits of agreement plotting.

RESULTS: Concentrations of Cu in serum ranged from 7.3 to 22 (mean 14.0) µmol/L, while concentrations in plasma ranged from 9 to 27 (mean 16.3) µmol/L. On average, concentrations of Cu in serum were 2.3 µmol/L lower than in plasma. Over the range of values seen in this study, concentrations of Cu in plasma and serum were significantly correlated (r=0.89), and mean concentrations in serum were 87% of those in plasma. There was no effect of flock or gender on the relationship between concentrations of Cu in serum and plasma. Despite the significant correlation, there was marked variability between individual samples in the proportion of Cu that was lost during clotting, with the 95% limits of agreement for serum Cu ranging from 70 to 104% of the plasma concentration.

CONCLUSIONS: As in cattle, the individual variability in the loss of Cu during clotting in sheep is too great for concentration of Cu in serum to be used as a substitute for that in plasma.

CLINICAL RELEVANCE: When assessing the blood Cu pool as part of the diagnosis of Cu-responsive disease in sheep, the concentration of Cu in plasma should be measured in preference to that of serum. We suggest that a range of 4.5 to 9 µmol/L in plasma be used to define marginal Cu status in sheep.     

Age-Dependent Immunolocalization of Fibronectin and Histological Changes in the Thymus of Rats

Age-dependent variations in the immunolocalization of fibronectin (FN) in the thymus were investigated in 1-, 6-, 12- and 20-month-old male and female Swiss albino rats (Rattus rattus) at the light-microscopic level and the changes with ageing in the histological structure of the thymus were also studied. There were no significant differences in the age-dependent variations in the immunolocalization of fibronectin or in the histological structure of the thymus between male and female rats of the same age but there were increases with ageing in the fibronectin content of the thymic capsule, the connective tissue between the lobules, around blood vessels, and in the medulla and cortex of thymus. The connective-tissue content between lobules, fat cells, Hassall's corpuscles, the thickness of capsule and the ratio of the medulla to the cortex of the lobules showed age-dependent increases in the thymus of rats of both sexes. Decreases in the organ weight/body weight ratio were also observed with ageing.     

不同周龄SPF级SD大鼠胰腺自发性病变的组织学观察

研究不同周龄SPF级SD大鼠胰腺自发性病变的种类及其病变发生率,为药物安全性评价提供背景资料。收集3年安评试验中11、19、31周龄试验对照组大鼠胰腺制作病理切片,光学显微镜下观察SD大鼠胰腺病变的种类及组织形态学特点,并统计其病变发生率。结果显示,大鼠胰腺主要出现了以下病变:①单核细胞浸润:11周龄大鼠该病变的总体发生率为0.6%,其中雌性为0,雄性为1.25%;19周龄大鼠该病变的总体发生率为1.0%,其中雌性为1.0%,雄性为1.0%;31周龄大鼠该病变的总体发生率为1.0%,其中雌性为0,雄性为1.96%。②腺泡细胞空泡变性:11周龄大鼠未观察到该病变的发生;19周龄大鼠该病变的总体发生率为1.0%,其中雌性为0,雄性为2.0%;31周龄大鼠该病变的总体发生率为3%,其中雌性为2.1%,雄性为3.9%。③腺泡细胞萎缩、腺管增生:11周龄大鼠未观察到该病变的发生;19周龄大鼠该病变的总体发生率为0.5%,其中雌性为0,雄性为1.0%;31周龄大鼠该病变的总体发生率为3.0%,其中雌性为1.0%,雄性为4.9%。结果表明,SPF级大鼠胰腺可发生单核细胞浸润、腺泡细胞空泡变性、腺泡细胞萎缩及腺管增生等自发性病变,且病变发生率可随着年龄的增加而增加。     

Variation of gene frequencies in ASIP, MC1R and GREY loci in Thoroughbred horses

The objective of the study has been to verify the hypothesis that the coat colour is regarded in the selection of Polish Thoroughbred horse population. Formally, the colour is not a selection criterion in this breed selected mainly for speed. The material consisted of twelve groups of foals registered in successive volumes of the Stud Book (11,688 foals, in total) and their parents selected to the breeding stud. The frequency of alleles in ASIP, MC1R and GREY loci controlling the coat colours was estimated from the recessive phenotype frequency square in the groups of foals. The inflow of foreign genes was limited and the population great, hence the migration effect was very low. The drift and Wahlund effect hardly influenced the genetic structure in the groups which enabled to analyze the population not divided. The total offspring frequency of recessive a, e and g alleles amounted to 0.1552, 0.4877 and 0.9773, respectively. Accuracy of the assessment of the a and e frequency was confirmed on the basis of test matings. The a, e and g alleles were more frequent in dams than in sires and the a alleles occurred more often in fillies than in colts. The frequency of a and e alleles was higher in the offspring than in the parents. The genotype distribution in the offspring differed from the expected one, assessed from the gamete frequency in sires and in dams. Fewer bay foals were born than anticipated. All the results show that the coat colour is not entirely disregarded in the breeding of Thoroughbred horses. The dominant A and E alleles producing the colour are preferred in the selection, particularly in the sires. This leads to some alterations in the phenotypic structure of the population. On the other hand, the horses are mated randomly, irrespective of the coat colour.     

短花针茅荒漠草地放牧系统微量元素季节变化及盈缺分析

为更有效地防治内蒙古自治区四子王旗地区家畜微量元素代谢病,合理使用微量元素添加剂,采用实地采样和实验室分析相结合的方法,对该地区短花针茅（Stipa breviflora）荒漠草地土壤-牧草-家畜生态系统中微量元素的水平进行检测。结果显示,土壤中铜和硒处于缺乏状态。牧草中铁和锰元素处于过量状态,硒为缺乏状态。与健康绵羊的各项指标相比较,血浆中铁和锰分别于夏秋季节和全年高于正常水平,硒和铜元素分别于秋季和冬季低于正常水平;肝脏中铁和锰全年高于正常水平,铜冬季低于临界值,硒元素秋冬季节低于正常水平;被毛中铁全年高于正常水平,而铜和硒全年低于正常水平。结合放牧绵羊对各种矿物质的进食量和消化率进行综合分析表明,该地区为高铁、高锰、低硒的生态环境,同时铜和锌处于季节性缺乏状态。