Avian influenza epidemic in Italy due to serovar H7N1

Beginning at the end of March 1999, a syndrome characterized by severe depression, anorexia, fever, and respiratory and enteric symptoms appeared in flocks of turkeys and, to a lesser extent, of chickens in the densely populated poultry-rearing regions of northeast Italy. The disease was characterized by sinusitis, tracheitis, peritonitis, and pancreatitis. The mortality varied between 5% and 90%. The disease was diagnosed as low pathogenic avian influenza, H7N1 serotype. After a summer period of declining cases, the disease reappeared in autumn exclusively in turkeys. Since the middle of December 1999, many farms of chickens, turkeys, and guinea fowl were abruptly affected by a highly pathogenic H7N1 virus, with very severe depression and mortality up to 100% in a few days. By the end of March 2000, nearly 500 farms, representing over 15 million birds, were affected or depopulated. To date, control measures have focused on improved biosecurity measures. Vaccine was not allowed, but its use was debated.     

Diallel analysis of partial resistance to an Iranian strain of bacterial leaf streak (Xanthomonascampestris pv. cerealis) in wheat

Six wheat genotypes with wide genetic variability for resistance to bacterial leaf streak were crossed in diallel fashion to determine the inheritance of resistance to this disease. Parental genotypes and their F1 hybrids were inoculated at the second leaf stage with an Iranian isolate of Xanthomonas campestris pv. cerealis . Two experiments were undertaken in a controlled environment chamber. Results showed that the genotypes IBPT66, IBPT84 and IBPT34 had a high level of partial resistance to the disease. General and specific combining abilities presented several significant positive or negative values, showing the importance of both additive and dominant genetic control for partial resistance to this bacterial disease. The resistant line IBPT66 could be a good donor of partial resistance to bacterial leaf streak in wheat.     

Nature of resistance to Striga hermonthica (Del.) Benth. parasitism in some Sorghum vulgare (Pers.) cultivars

Ten Sorghum vulgare (Pers.) cultivars varying in tolerance to Striga hermonthica (Del.) Benth. parasitism were grown with or without Striga infection. Endodermal thickening, pericycle lignification and silica crystal deposition were studied microscopically and measured for infected and non-infected sorghum cultivars. Although differences in the root character measurements were statistically significant they were not closely related to the response of the plant to infection. Low stimulant producing cultivars showed low or medium root cell thickening. The cv. Framida had both low stimulant production and high root cell thickening and was the best of the tolerant cultivars. High stimulant producing, tolerant cultivars generally showed heavy or intermediate cell thickening. The high stimulant producing, susceptible cultivar Debaikri also showed intermediate root cell thickening.‘Antibiosis', measured by the content of phenolic compounds in the plant, was then studied. Varietal differences in quality and quantity of phenolic substances in the roots and shoots of sorghum cultivars infected or non-infected with Striga were observed. Infection increased total phenolic contents in both shoot and root extracts. Differences in the total phenolic content in the shoot of non-infected cultivars did not reflect tolerance to Striga infection. The total phenolic acid content of the root extracts was closely related to the response of the host plant to Striga infection, tolerant cultivars having greater total phenolic acid content than susceptible ones.     

Decay in Norway Spruce Caused by Stereum sanguinolentum Alb. & Schw. ex Fr. Developing from Extraction Wounds

In two stands of Norway spruce (Picea abies (L.) Karst.), plantedin 1952 and 1929 in Yair Hill Forest and Glentress Forest, BordersRegion, two per cent of the trees examined in 1983 had extractiondamage on stems and superficial roots. Extraction wounds were4 and 8 years old respectively and ranged in size from 52 to1099 cm². Infection frequency of the damaged trees was 47 percent and 54 per cent respectively. Stereum sanguinolentum wasthe most common fungus isolated, accompanied by Trichodermaviride Fr; Chaetomium cochlioides Palliser and Heterobasidionannosum (Fr.) Bref. The frequency of isolation of S. sanguinolentumincreased progressively in samples taken from the outside ofstems inwards, whereas the other microorganisms present showedthe opposite pattern. In four trees, T. viride overgrew S. sanguinolentumin the the decay columns. Positive correlations were demonstratedbetween surface area of wounds and vertical extension of decay,tree volume and decay volume, and diameter of stem at breastheight (DBH) and decay volume; whereas a negative correlationoccurred between number of growth rings per 5 cm (measured inwardsfrom the outside of the bole) and radial penetration of decay.The results confirm the importance of S. sanguinolentum as awound pathogen.     

Effect of using okara meal,a by‐product from soymilk production as a dietary protein source for Nile tilapia (Oreochromis niloticus L.) mono‐sex males

The main objectives of this study was to evaluate the effect of partial and total replacement of fishmeal protein by okara meal (OM) protein in practical diets on growth performance, feed utilization and body composition of Nile tilapia (Oreochromis niloticus L.) mono‐sex males. Fish of an average initial weight of 2.67 ± 0.01 g were stocked in 15 glass aquariums (80 L each) at a rate of 15 fish per aquarium. Fishmeal protein (18% of the diet) was used as the sole source of animal protein in the control diet. Percent replacement of fish meal (FM) by OM on the basis of crude protein was as follows: 0% (control diet A), 25% (diet B), 50% (diet C), 75% (diet D) and 100% (diet E). Diets were fed to fish at a rate of 5%, and then gradually reduced to 4% of the total fish biomass daily, for a period of 12 weeks. The results revealed that the fish fed diets A (100% FM control), B (25% OM), C (50% OM) and D (75% OM) had significantly the best average body weight, weight gain g, specific growth rate (SGR % day^?1), weight gain % and feed intake g fish^?1 compared with diet E (100% OM) which had the lowest values. There were no significant differences (P > 0.05) among all experimental diets and control in terms of feed conversion ratio (FCR), protein efficiency ratio (PER) and survival rate %. Whole body protein contents for fish fed diets B, C and D were superior to the control diet. Incorporation of OM in the diets increased significantly whole body fat content. Incorporation of OM in the diets significantly increased apparent digestibility coefficient of crude protein crude fat and energy. Therefore, these findings suggest that up to 75% of FM protein can be replaced by OM protein in Nile tilapia, mono‐sex male diets.     

除草剂对土壤微生物生物量和氮矿化的影响

除草剂对土壤微生物生物量和氮矿化有不同的影响效应,这与除草剂类型、除草剂浓度、土壤类型以及包括温度、水分、培养时间等实验条件有关,这些影响效应在土壤肥力和环境保护上的重要性也进行了讨论。     

The effect of some cryoprotectants on dromedary camel frozen‐thawed semen

The cryopreserved camel semen is often associated with poor quality and fertility. This study aimed to improve the dromedary frozen semen quality by comparing the efficiency of four cryoprotectant agents (CPAs) on sperm freezability. Semen samples were collected from seven male Maghrabi camels, diluted with Shotor diluent supplemented with glycerol (Sh‐G), dimethyl formamide (DMF, Sh‐DF), dimethyl sulfoxide (DMSO, Sh‐DS) or ethylene glycol (EG, Sh‐EG), all at 6% final concentration, and the samples were subjected to cryopreservation. The results revealed the superiority of Sh‐DF over Sh‐G and Sh‐DS in terms of post‐thaw motility (55.83 ± 2.20 vs. 47.50 ± 4.33 and 45.00 ± 2.89%, respectively), sperm membrane (49.00 ± 0.58, 39.33 ± 3.33 and 42.67 ± 1.45%, respectively) and acrosomal integrities (53.00 ± 0.58, 57.33 ± 0.88 and 52.33 ± 1.45%, respectively). Sh‐EG group showed the lowest post‐thaw motility, plasma membrane and acrosome integrities (12.50 ± 1.44, 22.67 ± 1.45 and 30.67 ± 1.45, respectively). In conclusion, the protocols of dromedary camel semen cryopreservation could be enhanced using 6% DMF as a cryoprotectant agent.     

Natural co-infection of torque teno virus and porcine circovirus 2 in the reproductive apparatus of swine

This work aimed to detect and study natural co-infection of Circoviridae torque teno virus (TTV) and porcine circovirus 2 (PCV2) in the swine reproductive apparatus. Semen and organs from 17 boars were tested by nested and real-time PCR. PCV2 was amplified from semen (47%), lymph nodes (84.6%) and testicles (35.3%). TTV2 was amplified from 16/17 testis and 13/13 lymph nodes. TTV1 DNA was detected in fewer testicle samples (2/17), which were also TTV2 positive. Analyzed ovaries, follicular fluid and uteri of 83 culled sows showed TTV2, TTV1 and PCV2 from 49.3%, 30.1% and 6.0% of the sows, respectively. Sperm analysis indicated insignificant differences between PCV2 and TTVs positive and negative boars. The most frequent pathologic lesion in sows was endometritis (28.9%), but this was unassociated with PCV2 or TTVs detection. These findings question the importance of PCV2 and TTV2 natural co-infection in the pathology of porcine reproductive failures.