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SUMMARY The proportion of wool bale brands with a positive test for sheep lice in baled wool decreased from 29.5% in 1987/88 to 23.2% in 1990/91 before increasing to 38.2% in 1992/93. Changes in the proportion of wool bale brands with a positive test for lice were highly correlated with changes in the Wool Market Price Indicator. The increase in the proportion of positive lice tests since 1990/91 was associated with an increase in failures to eradicate lice from flocks. These failures were partly a consequence of the reduced use of lousicidal treatments, the development of resistance to synthetic pyrethroid chemicals and an increase in the transmission of lice between flocks. 相似文献
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T Tsutsui F Takahashi T Hori E Kawakami PW Concannon 《Reproduction in domestic animals》2009,44(S2):230-233
The fertile period for natural mating in dogs extends from before ovulation until day 5 post ovulation (PO) and involves a delay in oocyte maturation until 2–3 days PO and viability of secondary oocytes for 48–60 h or more. Spermatozoa do not enter the uterus after vaginal insemination in late oestrus. Cervical closure appears to occur on average 5 days PO, but conception may occur following intrauterine artificial insemination (IUAI) up to 8 days PO. Therefore, the present study was conducted to clarify the duration of fertility of canine ova. Using IUAI at 6, 7, 8 and 9 days PO (n = 5 bitches each) conception rates were 100%, 71.4%, 37.5% and 0%, respectively, with an average litter resorption rate of 30.8%, and with mean litter sizes and times to delivery PO being 4.3 ± 1.6 and 64.3 ± 0.3 days, 4.0 ± 1.4 and 66.3 ± 0.4 days, and 2.5 and 68 days for IUAI at 6, 7 and 8 days, respectively. The high pregnancy rates with IUAI at 6 and 7 days PO confirm that many canine oocytes are fertile at 4–5 days after maturation. The high rate of resorption was presumably because of aging of ova or asynchrony between embryonic development and the intrauterine environment. 相似文献
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PW Hellyer L Bai J Supon C Quail AE Wagner KR Mama KR Magnusson 《Veterinary anaesthesia and analgesia》2003,30(2):111-111
Ketamine, a noncompetitive NMDA receptor antagonist, has been shown to provide analgesia in some species. To target the NMDA receptor specifically and to potentially minimize some untoward side-effects, ketamine had been used epidurally. The objective of this study was to determine the analgesic effect of epidurally administered ketamine in dogs with chemically induced synovitis.
Sixteen healthy dogs were used. Dogs were anesthetized with propofol (4 mg kg−1 IV). Synovitis was induced by injecting 1 mL of sodium urate crystal solution (10 mg mL−1 ) into the right stifle. Dogs were allowed to recover and the synovitis was allowed to develop for 12 hours. The dogs were then anesthetized again using propofol (4 mg kg−1 IV). Lumbosacral epidural injections were performed with each dog receiving either 2 mg kg−1 of ketamine (20 mg mL−1 ) or an equal volume of placebo (sterile water containing not more than 0.1 mg mL−1 benzethonium chloride). Analgesia was assessed at baseline and then at 12, 14, 16, 18, 20, and 24 hours after induction of synovitis. Ground reaction forces (peak vertical force and impulse area) and overall pain were measured using a force platform and a pain scoring system (numerical rating scale).
Analysis of the data by Repeated Measures anova showed that the dogs developed a significant lameness between the baseline and 12 hours. However, no significant difference in ground reaction forces or total pain score was demonstrated between the treatment and control groups at any other time.
In conclusion, ketamine administered epidurally at a dose of 2 mg kg−1 did not provide significant analgesia in dogs with chemically induced synovitis. 相似文献
Sixteen healthy dogs were used. Dogs were anesthetized with propofol (4 mg kg
Analysis of the data by Repeated Measures anova showed that the dogs developed a significant lameness between the baseline and 12 hours. However, no significant difference in ground reaction forces or total pain score was demonstrated between the treatment and control groups at any other time.
In conclusion, ketamine administered epidurally at a dose of 2 mg kg
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The Kaap Valley pluton in South Africa is a tonalite intrusion associated with the Archean Barberton Greenstone Belt. Antipodal paleomagnetic directions determined from the central and marginal parts of the pluton record a geomagnetic reversal that occurred as the pluton cooled. The age of the reversal is constrained by an 40Ar/39Ar plateau age from hornblende at 3214 +/- 4 million years, making it the oldest known reversal. The data presented here suggest that Earth has had a reversing, perhaps dipolar, magnetic field since at least 3.2 billion years ago. 相似文献
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