Escherichia coli strains causing edema disease in northern Vietnam share an identical verotoxin 2e

Edema disease (ED) is a common fatal disease in newly weaned piglets. To develop an effective control program for ED, we carried out a study to better understand the incidence and spread of the disease and the characteristics of the causative agent. In our study, 69 Escherichia coli strains, isolated from 92 piglets showing clinical signs of ED from 13 provinces in northern Vietnam, were positive for both the VT2e toxin and the F18 major fimbrial subunit gene fedA. Of these, 40 strains (58%) were positive for AIDA and 16 isolates carried one or more enterotoxins. Forty-six (67%) of the 69 VT2e⁺/F18⁺ E. coli isolates belonged to classical serotypes (O139:K82, O141: K85, O138:K81, and O149:K91) while the remaining strains did not belong to the common serotypes in pig. Seropathotype 0139:K82⁺/VT2e⁺/F18⁺/AIDA⁺ (21 isolates) was the most frequently detected ED-causing E. coli strain. High prevalence of resistance was observed to the common drugs of tetracycline, streptomycin, trimethoprim/sulfamethoxazole, amoxicillin/clavulanic acid, and spectinomycin. Multiple resistances were widely distributed with 84% of isolates resistant to five antibiotics. Sequence analysis demonstrated that the VT2e toxin is identical among E. coli strains causing ED in pig.     

Effect of Parity,Season and FSH Treatment on the Calving Interval of Ayrshire Cows in the Tropics

A total of 607 calving intervals on 99 Ayrshire cows with parities from 1 to 10 and belonging to one dairy herd at Iringa in the southern highlands of Tanzania were analysed to study the effect of parity and season or month of calving on the subsequent calving interval. In addition, 22 calving intervals incorporating a superovulatory cycle were compared with those of 52 controls that had calved around the same period.The average (mean±SEM) age at first calving was 985±16 days. The effect of parity on calving interval was highly significant (p<0.001). Cows that calved in December, at the beginning of the rainy season, exhibited the shortest calving interval (404±13), while those that calved in September/October, in the dry season, exhibited the longest average calving interval (466±20 days), although this difference was not significant. Prior treatment with follicle-stimulating hormone to induce superovulation, significantly lengthened the average calving interval (579±28 vs 457±15 days; p<0.001).It was concluded that both parity and FSH treatment affected the calving interval. However, season (rainy vs dry) or month of calving did not influence this interval.     

Sex determination of bovine embryos based on embryonic cleavage rates

Bovine embryos (n = 64) collected at day-6 from 10 superovulated and inseminated donors were evaluated upon recovery and again after incubation for approx. 12 hrs. According to cleavage rate they could be divided into a fast, an intermediate and a slow developing group, respectively. This grouping was correlated to embryonic sex determined by karyotyping (n = 29). From the fast developing group we found 7 males and 2 females (male ratios 78%), from the intermediate group 3 males and 8 females (male ratio 27%) and from the slow group 1 male and 8 females (male ratio 11%). From this preliminary study it is concluded that the rate of embryonic development may be used as a sex discriminator.     

Fertilization in vitro of bovine oocytes: analysis of some factors affecting the fertilization rates.

Ovarian follicles were aspirated from superovulated heifers at different periods from the beginning of standing heat. The follicular fluid of these follicles was analyzed for progesterone, estradiol, testosterone and androstenedione concentrations and compared to the maturation stages of the oocytes and their ability to undergo fertilization in vitro. The results obtained suggest that high concentrations of progesterone, testosterone and androstenedione compared to a lower concentration of estradiol correspond to a high proportion of M-II oocytes and a high in vitro fertilization rate.     

Flow cytometric DNA-analysis of granulosa cells from preovulatory follicles in superovulated cows

Flow-cytometrische DNA-Analyse von Granulosazellen aus superovulierten, bovinen, präovulatorischen Follikeln In 68 Aspiraten aus präovulatorischen Follikeln von 14 superovulierten Kühen wurde der Anteil der Granulosazellen in der DNA-S-Phase des mitotischen Zyklus (“S-Fraktion”) sowie die Konzentrationen von Progesteron und Östradiol-17β in der Follikelflüssigkeit bestimmt. Zwischen der S-Fraktion und den Konzentrationen der gemessenen Steroidhormone in der Follikelflüssigkeit ergaben sich signifikante Zusammenhänge. Die mitotische Aktivität der Granulosazellen, d.h. die S-Fraktion, blieb bis zu 17 Stunden nach dem präovulatorischen LH-Peak unverändert. Anschließend erfolgte ein signifikanter Abfall bis zur 21.—23. Stunde. Diese Befunde konnen zur Beurteilung der präovulatorischen Periode herangezogen werden. Die S-Fraktion läuft sowohl mit den präovulatorischen follikulären Veränderungen als auch mit den Steroidkonzentrationelz der Follikelflüssigkeit parallel. Sie bietet dadurch eine Möglichkeit, das follikulare Stadium individuell ansprechen zu können. Indirekt ist damit auch eine Aussage über den Reifezustand der Oozyten möglich.     

Development after Separation and Reaggregation of Blastomeres from Early Pig Embryos cultured in vitro

The in vitro developmental potential of blastomeres from early porcine embryos war studied. Two-, 4-, and 8-cell embryos were separated into component blastomeres and replaced into zonae pellucidae in the following configurations (designated by number of blastomeresl original cell stage): half embryos (1/2, 2/4, and 4/8); quarter embryos (1/4 and 2/8); and eighth embryos (1/8). Culture was done in 50 μl droplets under paraffin oil in either Whitten's medium supplemented with 4 mg/ml bovine serum albumin (BSA) and 10% fetal calf serum (FCS) or in the same medium supplemented with porcine oviductal cells. Cultures were observed on a daily baris when the morphology was recorded and at the end of culture (144—168 h after the expected time of ovulation), the embryos were stained with Hoechst 33342 and cell counts made. Generally, no significant differences in developmental rate were found between the two culture system and the data was pooled. Blastocyst formation rate in half embryos was 23%, 28%, and 44% for 1/2, 2/4, and 4/8 embryos, respectively. The respective blastocysts contained an average of 24.3 ± 4.4 and 28.8 ± 2.0 versa 41.2 ± 6.4 cells (p < 0.05 and p < 0.05). Blastocyst formation rate in quarter embryos was 15% and 35% (p < 0.01) for 1/4 and 2/8 embryos, respectively and they possessed an average of 17.0 ± 1.8 and 22.8 ± 1.4 cells (p < 0.02), respectively. Blastocyst formation rate in 1/8 embryos was 9% and the blastocysts averaged 13.0 ± 1.3 cells. Two-,4-, and 8-cell control embryos formed blastocysts at rates of 22%, 85%, and 64%, respectively, and had average cell counts of 45.8 ± 10.8, 69.1 ± 4.0, and 75.4 ± 7.3, respectively. The timing of the initiation of blastocoel formation was similar for reaggregated and control embryos that started culture at the same stage. This along with the cell counts of reaggregated embryos at cavitation, which were proportional to the reduction in cell mars (7.2 ± 0.6, 12.6 ± 1.9, and 25.6 ± 2.8 for quarter, half and control embryos, respectively) supports the assumption that in pigs blastocoel formation occurs independent of the number of cells present. Inhalt: Entwicklung von frühen in vitro kultivierten Schweineblastomeren nach Abtrennung und Reaggregation Es wurde die Entwicklungspotenz von Blastomoren aus frühen Schweineembryonen studiert. Zwei-, Vier- und Achtzell-Embryonen wurden in ihre Blastomerenbestandteile zerlegt und nachfolgendem Schema in Zonae pellucidae zurückverbracht: Halbierte Embryonen (1/2, 2/4, 4/8) Viertelembrynnen (1/4 und 2/8) und Achtelembryonen (1/8). Die Kulturphase erfolgte in 50 μl Tropfen, die mit Parafinöl überschichtet waren. Es wurde Whitten's Medium, entweder mit 4 mg/ml BSA und 10% FCS verwendet oder das Medium mit porcinen Eileitenellen supplementiert. Die Kultur wurde täglich überpüft und die Morphologie beurteilt. Am Ende der Kulturzeit (144–168 Std nach dem berechneten Ovulationszeitpunkt) wurden die Embryonen mit dem Hoechstfarbstoff 33342 gefärbt und die Zellen gezählt. Signifikante Unterschiede in der Entwicklungsrate zwischen den beiden Medien wurden nicht gefunden und die Daten wurden zusammengefaβt. Die Blastozystenbildungsrate der Embryonenhälften betrug 23% und 44% für 1/2, 2/4 und 4/8 Embryonen. Diese Blastozysten enthielten im Mittel 24,3 ± 4,4 und 28 ± 2,0 gegenüber 41,2 ± 6,4 Zellen (p ≤ 0,05). Die Blastozystenbildungsrate aus Embryoversuchen betrug 1.5% und 35% (p ≤ 0,01) für 1/4 und 2/8 Embryonen. Im Mittel waren 17,0 ± 1,8 und 22,8 ± 1,4 Zellen (p ≤ 0,02) enhvickelt worden. Die Blastozystenbildungsrate in 1/8 Embryonen betrug 9% und durchschnittlich wurden 13,0 ± 1,3 Zellen in den gebildeten Blastozysten nachgewiesen. Zwei-, Vier- und Achtzell-Embryonen der Kontrollgruppe formten zu 22%, 85% und 64% Blastozysten und die mittlere Zellzahl betrug 45,8 ± 10,8, 69,1 ± 4,0 und 75,4 ± 7,3. Der Zeitpunkt der Blastozoelbildung war für reaggregierte und Kontrollembryonen ähnlich, wenn sie die Kulturphase im gleichen Enhvicklungsstadium begannen. Diese Tatsache und die vorhandene Zellzahl in reaggregierten Embryonen zum Zeitpunkt der Kavitation, die sich proportional zur Verringerung der Zellzaiilen verhielt (7,2 ± 0,6, 12,6 ± 1,9 und 25,6 ± 2,8 für Viertel-, Halb- und Kontrollembryonen), unterstützt die Annahme, daβ die Blastozoelbildung beim Schwein unabhängig yon der Zellzahl erfolgt.