Pulsed-field gel electrophoresis typing of Campylobacter fetus subsp. fetus isolated from sheep abortions in New Zealand

AIMS: To genotype Campylobacter fetus subsp. fetus isolates cultured from sheep abortions submitted to diagnostic laboratories in New Zealand during the year 2000 breeding season. To compare the types found nationally with those found in the Hawke' Bay region in 1999, and strains held in the New Zealand Reference Culture Collection, Medical Section (NZRM) from a study published in 1987.

METHODS: Campylobacter fetus subsp. fetus isolates cultured by veterinary diagnostic laboratories in the year 2000 breeding season, from sheep abortions from throughout New Zealand, were typed using pulsed-field gel electrophoresis (PFGE). In addition, seven freeze-dried C. fetus subsp. fetus isolates (strain numbers 2939–2945) from the NZRM, representing restriction types a–g found amongst sheep abortion isolates in a study published in 1987, were typed using PFGE.

RESULTS: In total, 293 C. fetus subsp. fetus isolates from 200 farms were obtained from veterinary diagnostic laboratories. Twenty-two distinct PFGE profiles were identified amongst the isolates. PFGE type B1 was predominant in each region of New Zealand and was identified from 66% of farms overall. Of the C. fetus subsp. fetus restriction types a–g lodged with the NZRM, 3/7 had PFGE profiles indistinguishable from profiles found in the current study. The other four restriction types had PFGE profiles that were unique but similar to those found in the current study.

CONCLUSIONS: PFGE type B1 was predominant amongst the C. fetus subsp. fetus isolates cultured from sheep abortions in each region of New Zealand in the year 2000, as was found in Hawke' Bay in 1999. The similarity between PFGE profiles of C. fetus subsp. fetus sheep abortion isolates from 1987 and 2000, and the relative prevalence of the PFGE groups, suggests that there has been no major genotypic shift in the population of C. fetus subsp. fetus implicated in sheep abortion in New Zealand during this time.     

Identifying factors which maximise the lambing performance of hoggets: a cross sectional study

AIM: To identity perceptions of farmers with respect to advantages of hogget lambing and to identify optimal management strategies for hogget lambing used in New Zealand.

METHODS: A questionnaire was sent to 1,038 sheep farmers in New Zealand who had indicated their hoggets would be lambing in 2002. Information was gathered on the practice of hogget lambing in New Zealand, in particular on the numbers and breeds of hoggets and rams used, selection criteria used for hoggets, use of teasers (vasectomised rams), length of mating period, use of mating crayons, vaccinations, medications and mineral supplements given, level of feed offered, use of pregnancy scanning, management during pregnancy and lambing, number of lambs present at docking, and shearing policies for hoggets. Farmers were also asked to indicate the relative importance of five stated reasons for choosing to have their hoggets mated in 2002.

RESULTS: A total of 629 (60.6%) responses were incorporated in the analysis, and the average percentage of hogget lambing was 60%. Use of vaccinations, length of the mating period, number of rams used, breed of hogget, weight at mating, management during lactation, and shearing policy were associated (p<0.05) with the lambing performance of hoggets, in the multivariate analysis.

CONCLUSIONS: This study indicated that to ensure high lambing percentages (LP) in hoggets in New Zealand, sheep farmers should: vaccinate hoggets against toxoplasmosis and campylobacteriosis; utilise a 40-day mating period; use 2.6–3.5% of rams during mating; incorporate Finn or East Friesian genetics; ensure liveweights at mating are as high as possible; manage single- and multiple-bearing/-rearing hoggets separately during the lambing and lactation periods; and shear hoggets pre-mating.     

The Effect of Parity of the Dam on Sexual Maturation,Serum Concentrations of Metabolic Hormones and the Response to Luteinizing Hormone Releasing Hormone in Bull Calves

The objectives of this study were to determine the effect of parity of the dam on age at which a scrotal circumference (SC) ≥ 28 cm was attained and the LH response to Luteinizing Hormone Releasing Hormone (LHRH) in bull calves. We also wanted to confirm, in a large group of bull calves, that the LH response to LHRH could be used to select early maturing bulls. Body weight and SC of the bull calves were measured every other week. At 15, 20 and 25 weeks of age, calves received 4.12 nm /kg body weight of LHRH ischio‐rectally and blood samples were taken every 15 min for 4 h. Calves from primiparous and multiparous dams were separated into two sub‐groups based on age at which an SC ≥ 28 cm was attained (early or late). An SC ≥ 28 cm was attained earlier in calves born to multiparous as compared with primiparous dams (p < 0.05). At 20 and 25 weeks of age, peak serum LH concentrations (LH‐peak) and area under the LH response curve (LH‐AUC) in response to LHRH were higher (p < 0.01) in calves born to multiparous as compared with primiparous dams. In calves born to multiparous dams the LH‐peak at 15 and 25 weeks of age and the LH‐AUC at 15 weeks of age were lower (p < 0.05) in calves that attained an SC ≥ 28 cm early as compared with late. The LHRH‐challenge test sensitivity and specificity ranged from 46% to 86%. We concluded that parity of the dam affected age at which SC ≥ 28 cm was attained and the LH response to LHRH in bull calves. Serum LH responses to LHRH at 15 and 25 weeks of age, in calves born to multiparous dams, show some promise for development into a test to select early maturing bull calves.     

In vitro production of porcine zygotes using intracytoplasmic injection of vitrified sperm

The objectives of this study were to evaluate if vitrified porcine spermatozoa are able to maintain their capacity to produce zygotes in vitro using intracytoplasmic sperm injection (ICSI) and to evaluate the zygote development in two in vitro atmospheric conditions: 5% CO₂ and tri‐gas. A group of porcine oocytes maturated in vitro were injected with vitrified‐warmed sperm (treatment group) and another group, with sperm diluted and conserved at 17°C (control group). To evidence parthenogenetic activation, some oocytes were submitted to a Sham test. The injected oocytes were cultured in G1 medium at 38°C, 100% humidity and 5% CO₂ or tri‐gas. No significant differences (p > .05) were observed in embryo development between the oocytes injected with vitrified‐warmed sperm (31.8%; 36/113), and those injected with semen diluted and conserved at 17°C (35.5%; 32/90), when cultured in 5% CO₂ or under tri‐gas atmosphere (42.9%; 39/91 vs. 34.2%; 26/76, respectively). No significant differences (p > .05) were observed in the percentage of pronuclei (PN) obtained between 5% CO₂ and tri‐gas, within each treatment either. Of the 52 oocytes submitted to the Sham test, only two presented a female PN (activation) indicating that the PN observed in the treatment group were a product of fertilization and not parthenogenetic activation. To conclude, porcine sperm vitrified using spheres, at a concentration of 5 × 10⁶ spermatozoa/ml in TALP medium with 1% bovine serum albumin (BSA), conserve condensed and intact chromatin capable of producing early embryo development up to the pronuclear stage.     

Association Between ETFA Genotype and Activity of Superoxide Dismutase,Catalase and Glutathione Peroxidase in Cryopreserved Sperm of Holstein–Friesian Bulls

The aim of this study was to determine whether C/T missense mutation within the ETFA gene is associated with sperm antioxidant enzymatic activity. One hundred and twenty Holstein–Friesian bulls were genotyped by the PCR‐RFLP technique (MwoI). Commercial straws of frozen‐thawed semen were used to evaluate the activity of three antioxidant enzymes: superoxide dismutase, catalase and glutathione peroxidase. Among all bulls investigated, genotype CT was the most frequent (44.2%), in comparison with CC (42.5%) and TT (13.3%). Significant differences in glutathione peroxidase activity were observed between homozygous individuals (CC vs TT) with heterozygous CT having intermediate values. Dismutase activity was significantly associated with ETFA genotype, although only bulls with the CT genotype were significantly different from bulls carrying the CC genotype. The activity of catalase showed a similar trend (but was not statistically significant). In conclusion, we found that bulls with the ETFA TT genotype produce sperm with the highest glutathione peroxidase activity and can therefore be more efficiently protected from reactive oxygen. The mechanism of this interaction needs to be elucidated in future research.     

The horse-racetrack interface: a preliminary study on the effect of shoeing on impact trauma using a novel wireless data acquisition system

REASONS FOR PERFORMING STUDY: There is a need to determine accelerations acting on the equine hoof under field conditions in order to better assess the risks for orthopaedic health associated with shoeing practices and/or surface conditions. OBJECTIVES: To measure the acceleration profiles generated in Thoroughbred racehorses exercising at high speeds over dirt racetracks and specifically to evaluate the effect of a toe grab shoe compared to a flat racing plate, using a newly developed wireless data acquisition system (WDAS). METHODS: Four Thoroughbred racehorses in training and racing were used. Based on previous trials, each horse served as its own control for speed trials, with shoe type as variable. Horses were evaluated at speeds ranging from 12.0-17.3 m/sec. Impact accelerations, acceleration on break over and take-off, and temporal stride parameters were calculated. Impact injury scores were also determined, using peak accelerations and the time over which they occurred. RESULTS: Recorded accelerations for the resultant vector (all horses all speeds) calculated from triaxial accelerometers ranged 96.3-251.1 g, depending on the phase of the impact event. An association was observed between shoe type and change in acceleration in individual horses, with 2 horses having increased g on initial impact with toe grab shoes in place. In the final impact phase, one horse had an increase of 110 g while wearing toe grab shoes. Increased accelerations were also observed on break over in 2 horses while wearing toe grab shoes. CONCLUSIONS: Shoe type may change impact accelerations significantly in an individual horse and could represent increased risk for injury. Further work is needed to determine if trends exist across a population. POTENTIAL RELEVANCE: The WDAS could be used for performance evaluation in individual horses to evaluate any component of the horse-performance surface interface, with the goal of minimising risk and optimising performance.