Effect of Suppression of FSH with a GnRH Antagonist (Acyline) Before and During Follicle Deviation in the Mare

A GnRH antagonist (Acyline) was used to study the role of FSH in early development of a follicular wave in 61 mares. In Experiment 1, a single dose of 3 mg per mare, compared with 0 and 1 mg, suppressed both the FSH and follicle responses to exogenous GnRH. In Experiment 2, high concentrations of FSH were induced by two successive ablations of all follicles ≥ 6 mm on days 10 and 13 (day 0 = ovulation). A single treatment with Acyline resulted in significantly greater suppression of plasma concentrations of FSH than a single treatment with charcoal-extracted follicular fluid (source of inhibin) or oestradiol. Suppression of FSH was not significantly different between the group treated with Acyline alone and a group treated with a combination of Acyline, inhibin and oestradiol. In Experiment 3, all follicles were ablated on day 10 to induce an FSH surge and a new follicular wave. Acyline treatment on day 10 resulted in an immediate decrease in FSH, without a significant effect on day of emergence of a new wave or growth of follicles from 7 to 11 mm on days 11–13. Treatment on day 15, a day before expected follicle deviation and after the peak of the wave-stimulating FSH surge, resulted in an immediate decrease in FSH and cessation of follicle growth. Results indicated that growth of follicles for about 2 days after wave emergence was independent of FSH. In contrast, during the decline in the wave-stimulating FSH surge and before follicle deviation, growth of follicles was dependent on FSH.     

Groei en produksie van ‘n aanal aangeplante weidings onder beweiding

Uittreksel

Die groei en produksie onder beweiding van ‘n aantal aangeplante weidings is met behulp van die verskilmetode bepaal. Uit die data verkry in die proef is dit duidelik dat indien daar besproeiingswater beskikbaar is, groen materiaal dwarsdeur die jaar voorsien kan word. Spesies wat in so ‘n kombinasie gebruik kan word, is byvoorbeeld Dactylis glomerata, Festuca arundina‐ceae, Lolium multiflorum en Digitaria eriantha. D. eriantha kan egter met Eragrostis curvula, Cynodon dactylon of Medicago sativa vervang word. Loliumperenne het die laagste droëmateriaalproduksie van al die spesies onder besproeiing gelewer.     

Culicoides species associated with sheep in the Netherlands and the effect of a permethrin insecticide

Culicoides spp. act as vectors for a number of viral diseases of animals including bluetongue in sheep. The aims of this study were to determine: (1) which Culicoides spp. are associated with sheep in The Netherlands; (2) the time of the day when they are most active; and (3) the effect of treatment of animals with a permethrin insecticide. Two pairs of sheep were each housed within mosquito tents of either one or two layers of netting and all trapped Culicoides spp. were identified microscopically. For the permethrin insecticide study, one of two pairs of sheep was treated with 3.6% permethrin and all animals were housed in tents of similar design. Of the 6210 midges captured, 54.1% were identified as C. chiopterus and 42.7% as C. obsoletus. C. imicola was not identified. The average insect feeding rate was 35-40% and midge activity was greatest around sunset. Permethrin treatment reduced the number of midges captured by 50% and also resulted in a decrease in the percentage of midges that had fed. The findings provide useful information on the behaviour and distribution of Culicoides spp. that will facilitate the development of appropriate control strategies to minimise the risk of insect-vector borne virus diseases such as bluetongue.     

Treatment of virulent footrot with lincomycin and spectinomycin

A mixture of lincomycin and spectinomycin was investigated as a treatment for footrot in sheep. In a controlled clinical trial 92.5% of acute and chronic cases of virulent footrot were cured following a single intramuscular injection of a mixture containing 50 mg lincomycin and 100 mg spectinomycin/ml at a dose rate of 1 ml/10 kg bodyweight. No improvement in clinical response was observed in groups of sheep treated on 3 successive days with this dose rate nor in another group treated once at a dose rate 1 ml/3.3 kg bodyweight. Cure effectiveness of each of the 3 treatment groups relative to untreated controls was 89%, 95% and 95%. Efficacy of lincomycin/spectinomycin was compared with that of penicillin/streptomycin in the treatment of footrot on 2 farms in south western New South Wales. Assessments made 14 to 17 d after treatment showed that on one farm all 122 ewes treated with lincomycin/spectinomycin had recovered while 170 of 175 ewes treated with penicillin/streptomycin recovered in the same period. On the second farm 87 of 90 ewes treated with lincomycin/spectinomycin recovered, compared with 184 of 190 sheep in the same flock treated with penicillin/streptomycin. Supportive footbathing did not seem to improve the clinical response in either treatment group and the paring done was sufficient only to establish diagnosis and to remove grossly overgrown horn.     

温度对荔枝开花的影响

低温能促进荔枝（LitchichinestsSonn．）开花,但是成功诱导开花的临界温度和所需低温量并不清楚。研究了最高温／最低温：15°／5°,20°／5°,20°／10°,20°／15°,25°／10°,25°／15°,25°／20°和30°／20℃8个温度处理对KwaiMayPink荔枝和Casino荔枝营养生长和开花的影响。在第2个试验中,WaiChee荔枝在转移到无诱导条件的30°／20℃温度前,分别给予0,2,4,6,8,10和31周的15℃低温诱导。在第3个试验中．WaiChee荔枝生长温度为15℃时,每24小时内给予高于20℃的温度处理时间分别为0,1,2和8h（15℃以上分别为0,2,4和15h）。在第1个试验中,KwaiMayPink的营养生长温度为25°／20℃和30°／20℃,温度为25°／10℃和25°／15℃时,既有营养生长,又有花穗发育,较低的温度更利于开花。Casino荔枝除了在25°／10℃和25°／15℃的温度条件下既无营养生长,也无花穗发育外,其余处理的反映和KwaiMayPink荔枝类似。对2个荔枝品种而言,在20°／15℃和更低的温度时,几乎所有枝条都开了花。‘WaiChee’荔枝成花诱导条件为在转移到高温条件下之前,保持15℃的低温4周,最长6周。低温时间的长短还影响花穗的类型,15℃的低温诱导10周后,‘WaiChee’荔枝几乎无有叶花穗。保持15℃的低温