A QUANTITATIVE STUDY OF THE FIBRINOLYSIN-ANTIFIBRINOLYSIN REACTION

The results of a study of the streptococcal fibrinolysin reaction and its inhibition by sera containing specific antibody are presented. It was possible to devise a quantitative antifibrinolysin test by controlling the various factors influencing the reaction. In man, the antifibrinolysin response was found to vary according to the strain of streptococcus responsible for the infection.     

油桐早实丰产技术研究报告

油桐早实丰产技术的研究是“七五”国家科技重点攻关项目。项目要求从1986年至1990年的5年内完成油桐丰产试验林面积2000亩,从第三年开始亩产桐油2-3kg,进入盛果期亩产桐油20-25kg。经6年的努力,实际完成丰产林面积2037.5亩,超额1.7％。从1988年至1991年4年累产桐油89932.8kg,连同林地间种总收入是582208.6元,扣除科研投资30万元(地方资助5万元),盈余28万元。丰产林产生的辐射效应,带动农户造桐林1万余亩。每亩多增收30元,则有30万元。油桐早实丰产技术研究,不仅为油桐生产提供应用技术,并且也直接创造了经济效益。本课题所营造的丰产林获得成功的关键技术是实现了栽培良种化,应用立地类型划分的方法。正确选择宜桐林地,合理调整林分结构,运用生态系统的理论和方法,集约化经营好桐林,这是丰产的保证。同时在试验研究的全过程中,贯彻执行了正确的科研指导思想和技术路线。     

Genetic parameters and genotype x environment interaction for feed efficiency traits in steers fed grower and finisher diets

The objective of this study was to examine the genetic parameters and genetic correlations of feed efficiency traits in steers (n = 490) fed grower or finisher diets in 2 feeding periods. A bivariate model was used to estimate phenotypic and genetic parameters using steers that received the grower and finisher diets in successive feeding periods, whereas a repeated animal model was used to estimate the permanent environmental effects. Genetic correlations between the grower-fed and finisher-fed regimens were 0.50 ± 0.48 and 0.78 ± 0.43 for residual feed intake (RFI) and G:F, respectively. The moderate genetic correlation between the 2 feeding regimens may indicate the presence of a genotype × environment interaction for RFI. Permanent environmental effects (expressed in percentage of phenotypic variance) were detected in the grower-fed steers for ADG (38%), DMI (30%), RFI (18%), and G:F (40%) and also in the finisher-fed steers for ADG (28%), DMI (35%), metabolic mid-weight (23%), and RFI (10%). Heritability estimates were 0.08 ± 0.10 and 0.14 ± 0.15 for the grower-fed steers and 0.42 ± 0.16 and 0.40 ± 17 for the finisher-fed steers for RFI and G:F, respectively. The dependency of the RFI on the feeding regimen may have serious implications when selecting animals in the beef industry. Because of the higher cost of grains, feed efficiency in the feedlot might be overemphasized, whereas efficiency in the cow herd and the backgrounding segments may have less emphasis. These results may also favor the retention (for subsequent breeding) of cows whose steers were efficient in the feedlot sector. Therefore, comprehensive feeding trials may be necessary to provide more insight into the mechanisms surrounding genotype × environment interaction in steers.     

采用综合技术措施快速育肥肉兔

Feeding pelteobagrus fulvidraco in cyclic-water tank with six different feeds over aperiod of sixty days.The results are shown as follows1.The frequency of occurrence of the foods on the stomach of pelteodagrus fulvidracocomplete feedI,I,Sliver carp meat＞pond-snail meat,pig meat＞mud-fish meat,complete feed II.Inthe case of the growth,similar changes arenoticed.2.After feeding,the protease and diastase activities of stomach and intestine show asignificant rising(p＜0.05).3.The oxygen consumption rate of pelteobagrus fulvidraco is144mg/h.kg,and increases by 13.8%than before trial,suffocation point is0.309mg/l(p＞0.05).     

Accuracy of genomic breeding values for residual feed intake in crossbred beef cattle

The benefit of using genomic breeding values (GEBV) in predicting ADG, DMI, and residual feed intake for an admixed population was investigated. Phenotypic data consisting of individual daily feed intake measurements for 721 beef cattle steers tested over 5 yr was available for analysis. The animals used were an admixed population of spring-born steers, progeny of a cross between 3 sire breeds and a composite dam line. Training and validation data sets were defined by randomly splitting the data into training and testing data sets based on sire family so that there was no overlap of sires in the 2 sets. The random split was replicated to obtain 5 separate data sets. Two methods (BayesB and random regression BLUP) were used to estimate marker effects and to define marker panels and ultimately the GEBV. The accuracy of prediction (the correlation between the phenotypes and GEBV) was compared between SNP panels. Accuracy for all traits was low, ranging from 0.223 to 0.479 for marker panels with 200 SNP, and 0.114 to 0.246 for marker panels with 37,959 SNP, depending on the genomic selection method used. This was less than accuracies observed for polygenic EBV accuracies, which ranged from 0.504 to 0.602. The results obtained from this study demonstrate that the utility of genetic markers for genomic prediction of residual feed intake in beef cattle may be suboptimal. Differences in accuracy were observed between sire breeds when the random regression BLUP method was used, which may imply that the correlations obtained by this method were confounded by the ability of the selected SNP to trace breed differences. This may also suggest that prediction equations derived from such an admixed population may be useful only in populations of similar composition. Given the sample size used in this study, there is a need for increased feed intake testing if substantially greater accuracies are to be achieved.