Long‐term Effects of Pyrethrin and Cyfluthrin,a Type II Synthetic Pyrethroid,Insecticide Applications on Bull Reproductive Parameters

The objectives of this study were to determine effects of cyfluthrin and pyrethrin spray products, used in combination with cyfluthrin topical and ear tag applications, on bull reproductive parameters over 18 weeks. Angus or Angus x Simmental bulls were randomly assigned to one of three treatment groups: (i) no exposure to pyrethrins/cyfluthrin (CONT; n = 10), (ii) cyfluthrin ear tag and topical applications (ET; n = 10), or (iii) cyfluthrin ear tag, topical, premise spray and pyrethrin fog spray applications (ET+S; n = 8). Bull body weight was measured every 3 week, and body condition score and scrotal circumference were recorded on weeks 0, 9 and 18. Semen and serum were collected every 3 weeks for sperm evaluation and testosterone measurement, respectively. There was a treatment × week interaction (p < 0.01) for sperm with primary defects; bulls in CONT group had a greater (p = 0.01) percentage of sperm with primary defects than bulls treated with insecticides at week 18. Overall and progressive sperm motility, normal sperm morphology, secondary sperm defects and serum testosterone concentrations changed (p < 0.01) over time in all bulls; however, treatment did not affect (p ≥ 0.13) any of these parameters. There were also no treatment effects (p ≥ 0.08) on bull body weight, body condition score or scrotal circumference. The use of pyrethrin‐ and cyfluthrin‐based insecticides, regardless of application, did not negatively affect reproductive parameters in beef bulls when administered over 18 weeks.     

群养鸡谨防痢菌净中毒

痢菌净学名乙酰甲喹,是我国研制的具有自主知识产权的兽用抗菌药品.本品抗菌谱广,不易产生抗药性,价格低廉,在畜牧养殖业上应用广泛.但在使用过程中常因超剂量应用导致中毒现象发生,造成不应有的损失.本文从药品特性、中毒症状、剖检变化、治疗、中毒原因分析等五个方面对群养鸡痢菌净中毒做了详尽阐述,以期基层兽医临床工作者有所借签.     

Magnetic Field and Plasma Observations at Mars: Initial Results of the Mars Global Surveyor Mission

The magnetometer and electron reflectometer investigation (MAG/ER) on the Mars Global Surveyor spacecraft has obtained magnetic field and plasma observations throughout the near-Mars environment, from beyond the influence of Mars to just above the surface (at an altitude of approximately 100 kilometers). The solar wind interaction with Mars is in many ways similar to that at Venus and at an active comet, that is, primarily an ionospheric-atmospheric interaction. No significant planetary magnetic field of global scale has been detected to date (<2 x 10(21) Gauss-cubic centimeter), but here the discovery of multiple magnetic anomalies of small spatial scale in the crust of Mars is reported.     

Prevalence of antibodies to Encephalitozoon cuniculi in stray dogs as determined by an ELISA

An ELISA, using Encephalitozoon cuniculi spores as antigen, was used to determine the prevalence of specific anti-E cuniculi IgG in a group of stray dogs. In a preliminary survey 51 of 248 sera were classified as positive with titres of 1:400 to 1:3200. The 18 sera with titres of 1:400 were reclassified as negative when no IgG binding to the spores could be detected by comparison with a standard curve of anti-E cuniculi IgG. The remaining 33 sera (13.3 per cent) were classified as low, moderate or strong positives. Comparison of total IgG and specific IgG showed that specific IgG was greatly increased in the moderately and strongly positive sera. E cuniculi may be of importance as one cause of fading puppy syndrome when transmitted transplacentally, and as a complicating infection in human immunodeficiency diseases.     

Characterisation of Pasteurella multocida isolated from fowl cholera outbreaks on turkey farms

SUMMARY: Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate Pasteurella multocida isolates from outbreaks of fowl cholera on 7 turkey farms in New South Wales. While only a single isolate was available from 5 of the farms, multiple isolates, 4 and 12 respectively, were available from the other 2 farms. The available field evidence suggested that 8 outbreaks had occurred with one farm suffering 2 outbreaks. The isolates obtained were all confirmed as Pasteurella multocida . Biochemical profiles allocated the isolates to 4 groups, 3 being variants of P multocida subsp multocida and the fourth being P multocida subsp septica . REA performed with Hpall established 7 groups. Ribotyping using the Hpall digests probed with the 16S rRNA operon of Haemophilus paragallinarum recognised the same 7 groups as REA. Unlike the biochemical profiles, both REA and ribotyping provided a fine subdivision that identified outbreaks as either related or unrelated. The REA and ribotyping patterns as well as biochemical profiles were stable for all isolates from the outbreaks in which multiple isolates were obtained from either the same bird or from different birds. REA and ribotyping were found to be superior to biotyping methods for the investigation of fowl cholera outbreaks.     

Local Effect of the Corpus Luteum on Ovarian Follicular Functional and Morphological Features in the Goat

Ovaries of unilaterally ovulated goats (n=21) were used to study follicular morphological features (proportion and degree of atresia, oestradiol production in vitro and progesterone production of granulosa cells in culture). Follicles were dissected out and classified as small (1–2 mm), medium (2–4 mm) and large (>4 mm). Morphological and physiological features were compared in each size class between ovaries bearing and not bearing corpora lutea (CLO and NCLO, respectively). Within the same size class, there was no difference in proportion or in degree of atresia, between CLO and NCLO. A significant effect of follicular size on oestradiol production in vitro was detected, but no effect of the corpus luteum was found. Finally, progesterone production of granulosa cells in culture was significantly higher in CLO than in NCLO after 24 h (p < 0.05) and also after 90 h (p < 0.01) of culture. This higher progesterone production by CLO granulosa cells in culture could be explained by local influence of the corpus luteum stimulating the steroidogenic activity but not aromatase activity. Further studies are needed to clarify possible factors and pathways for this local effect of the corpus luteum upon follicular physiology.     

The Effects of Sample Size on the Outcome of Ovarian Tissue Cryopreservation

Cryopreservation of ovarian tissue is known to affect follicular survival. Several variables may be responsible for this. Little attention has focused on the effect of the size of the fragment to be cryopreserved. This study was conducted to assess the effect of the size of the tissue on follicular histology after freezing with 1,2-propanediol. Histological evaluations were performed of control and cryopreserved tissue. Fragments were cut 10 × 3 × 2 mm³ (2 mm group) or 10 × 3 × 4 mm³ (4 mm group). Percentages of normal follicles in control fragments cut into 2 and 4 mm slices were 56% and 34%, respectively. The relative risks to obtain normal follicles in the 2 mm and the 4 mm fragments after cryopreservation were 0.63 and 0.47, respectively. Freezing reduced follicle survival to a significantly greater extent in the larger tissue fragments. There is an increased risk of damage to primary and primordial follicles, when the tissue slices are cut with all dimensions larger than 2 mm.