Study on prevalence and bacterial etiology of mastitis,and effects of subclinical mastitis and stage of lactation on SCC in dairy goats in Egypt

Tropical Animal Health and Production - In Egypt, inadequate information on prevalence and epidemiology of caprine mastitis is available. This study was designed to investigate prevalence and...     

Procedure for bovine ICSI, not sperm freeze-drying, impairs the function of the microtubule-organizing center

This study was designed to investigate whether freeze-dried (FD) bull spermatozoa maintained the function of the microtubule-organizing center (MTOC) after rehydration and intracytoplasmic sperm injection (ICSI). In a preliminary attempt, the cleavage and blastocyst formation rates in FD-ICSI zygotes (36 and 1%, respectively) were found to be considerably lower than those in control ICSI zygotes (67 and 21%, respectively) or in IVF zygotes (78 and 43%, respectively). An alkaline comet assay indicated that the DNA fragmentation index (length of comet tail % DNA liberated) was not significantly different between fresh and FD spermatozoa. In the main experiment, formation of sperm-asters in the FD-ICSI oocytes 7 h postinsemination occurred at a similar rate when compared with the control ICSI oocytes (41 vs. 49%). Among the oocytes exhibiting sperm aster formation, the extent of microtubule network assembly was comparable between the FD-ICSI and control ICSI groups. However, the MTOC of the ICSI oocytes was not as functional as that of IVF oocytes in terms of the aster formation rate (97%) and the fluorescent intensity of the microtubule network (2.0 folds). These results suggest that the freeze-drying process per se had no adverse effect on maintaining the MTOC function in bull spermatozoa.     

Challenging endeavour for preservation of freeze-dried mammalian spermatozoa

Freeze-drying (lyophilization) has been proposed as an alternative method for sperm preservation to overcome the disadvantages of the current cryopreservation method such as the high maintenance cost of frozen stocks, the problems associated with transportation of frozen materials and the potential risk of total loss of the frozen stock. Since freeze-dried spermatozoa after rehydration lose their motility, which is an essential requirement to complete physiological fertilization, a relatively difficult microinsemination technique must be applied to rehydrated spermatozoa. Theoretically, it has been supposed that freeze-dried spermatozoa could maintain their functions and abilities to interact with the oocyte cytoplasm after prolonged storage at refrigerator temperature. However, sufficient yield of transferable blastocysts and production of live offspring derived from freeze-dried sperm samples are still subjects to be challenged and overcome in large domestic species.     

Effects of dietary marine microalgae,Tetraselmis suecica,on production,gene expression,protein markers and bacterial count of Pacific white shrimp Litopenaeus vannamei

The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin‐like growth factor 2 (IGF‐II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40‐L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg^?1 dried T. suecica (T1), 5 g kg^?1 dried T. suecica (T2) and 7.5 g kg^?1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF‐II was higher in the T2 group. The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.     

Natural co‐infection of cultured Nile tilapia Oreochromis niloticus with Aeromonas hydrophila and Gyrodactylus cichlidarum experiencing high mortality during summer

Aeromonas hydrophila and Gyrodactylus cichlidarum are common pathogens that induce significant economic losses in farm‐reared Nile tilapia. Nowadays, the sudden appearance of fish mortalities was exaggerated due to mixed and multiple infections. During summer 2016, mass mortality among earthen pond‐farmed Nile tilapia was reported. Clinico‐pathological, bacteriological and parasitological examinations have been demonstrated. As well, the water quality parameters were assessed. The clinical and histopathological findings of the moribund and recently dead fish were characterized by generalized septicaemic signs. The water quality parameters were significantly elevated over the permissible levels, whereas there was an elevation in nitrite (0.04 mg/L), un‐ionized ammonia (0.8 mg/L), hydrogen sulphide levels (153.1 mg/L) and organic matter content (3.79 mg/L). A. hydrophila was identified based on phenotypic characterization, API 20E features and the homology of 16S rRNA gene sequence analysis. In addition, PCR data confirmed the presence of aerolysin (aerA) and haemolysin (hly) genes in the identified A. hydrophila isolates. Gene sequencing and phylogenetic analysis based on 16S rRNA sequence confirmed that A. hydrophila H/A (accession No. MN726928) of the present study displayed 98%–99% identity with the 16S rRNA gene of A. hydrophila. Furthermore, the monogenetic trematode, G. cichlidarum was identified in the wet mounts from the skin and gills of the examined fish with a high infestation rate. In this context, it was reported that the synergistic co‐infection of A. hydrophila and G. cichlidarum with deteriorated water quality parameters could induce exaggerated fish mortalities during hot weather.     

Antibacterial effect of carbon nanofibers containing Ag nanoparticles

Silver nanoparticles imbedded in polyacrylonitrile (PAN) nanofibers and converted into carbon nanofibers by calcination was obtained in a simple three-step process. The first step involves conversion of silver ions to metallic silver nanoparticles, through reduction of silver nitrate with dilute solution of PAN. The second step involves electrospinning of viscous PAN solution containing silver nanoparticles, thus obtaining PAN nanofibers containing silver nanoparticles. The third step was converting PAN/Ag composites into carbon nanofibers containing silver nanoparticles. Scanning electron microscopy (SEM) revealed that the diameter of the nanofibers ranged between 200 and 800 nm. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) showed silver nanoparticles dispersed on the surface of the carbon nanofibers. The obtained fiber was fully characterized by measuring and comparing the FTIR spectra and thermogravimetric analysis (TGA) diagrams of PAN nanofiber with and without imbedded silver nanoparticles, in order to show the effect of silver nanoparticles on the electrospun fiber properties. The obtained carbon/Ag composites were tested as gram-class-independent antibacterial agent. The electrosorption of different salt solutions with the fabricated carbon/Ag composite film electrodes was studied.     

Host cholesterol synthesis contributes to growth of intracellular Toxoplasma gondii in macrophages

The intracellular protozoan Toxoplasma gondii lacks the ability to synthesize sterol and scavenges cholesterol from the low-density lipoprotein receptor (LDLR) pathway of its host to facilitate replication. Sterol biosynthesis inhibitors, however, have a demonstrated anti-Toxoplasma effect. In this study, we examined the host mevalonate pathway as a novel source of cholesterol for T. gondii and its effects on parasite growth in macrophages. Parasite growth did not significantly change in the absence of LDLR or when LDL was exogenously supplemented. Lovastatin and compactin, both inhibitors of hydroxymethylglutaryl-CoA (HMG-CoA) reductase in the mevalonate pathway, significantly inhibited T. gondii growth in both wild-type and LDLR-knockout macrophages. Parasite growth was also suppressed by squalestatin, an inhibitor of squalene synthase, despite mevalonate producing isoprenoid intermediates in host cells. The present study demonstrates that lovastatin, compactin and squalestatin have anti-Toxoplasma activities and that the host cholesterol synthesis may contribute to parasite growth in macrophages.     

Influence of low levels of dietary aflatoxins on Eimeria tenella infections in broilers

The present study was conducted to evaluate the adverse effects of an interaction between low levels of dietary aflatoxins (AF) and Eimeria tenella infection on broiler chicks. A set of 1-day-old chicks were raised for 35 days in the following groups: a control group, a group fed AF, a group fed AF and inoculated with E. tenella (AF + E.ten), and a group inoculated with E. tenella alone. AF in the contaminated diet were given at 200 ppb starting from the seventh day after hatching while E. tenella was inoculated at a dose of 5 × 10⁴ sporulated oocysts per chick at the 14th day after hatching. Worsened performance traits and high mortality were all observed in the treated birds, particularly the AF + E.ten group. Lesion scores and oocyst outputs were not different within groups. Chickens fed with AF had significantly increased serum ALT and ALP activities as well as decreased albumin content. They also showed hepatomegaly, hepatocytic vacuolation and necrosis, an atrophied bursa of Fabricius, and a thymus with tissue depletion. E. tenella-infected broilers displayed a significant reduction in packed cell volume, hemoglobin content and lymphocyte percentage, and showed hemorrhagic typhlitis. The deficits in hepatic function and hematologic parameters as well as the gross pathological, and histopathological changes, were more common and more severe in the group that was exposed to both aflatoxicosis and coccidiosis than in the groups exposed to either treatment alone. Thus, the combination of aflatoxicosis and E. tenella infection may influence the course of coccidial infection due to additive effects.