A comparison of the effect of short-acting and long-acting cloxacillin-based dry-cow therapy on somatic cell counts after calving in cows also given internal teat sealants

AIM: To compare, in cows treated with an internal teat sealant, the effect of short-acting and long-acting cloxacillin-based dry-cow therapy on somatic cell counts (SCC) after calving.

METHODS: Cows from a spring-calving, pasture-based dairy farm in the Manawatu-Whanganui region of New Zealand were randomly allocated to receive either a short-acting cloxacillin and ampicillin dry-cow therapy and internal teat sealant (n=291) or a long-acting cloxacillin and ampicillin dry-cow therapy and internal teat sealant (n=288) at the end of lactation. Cows were managed on-farm with routine husbandry procedures through the dry period and following calving. A multivariable logistic regression model was used to determine the association between length of action of dry-cow therapy and the proportion of cows with a SCC >150,000?cells/mL at the first herd test after calving.

RESULTS: Age of cow, mean SCC for the preceding season and interval from calving to the first post-calving herd test were all associated with the proportion of cows with an individual SCC >150,000?cells/mL at the first herd test (p<0.001) Treatment with the short-acting dry-cow therapy was not associated with decreased odds of cows having a SCC >150,000?cells/mL at the first herd test compared with treatment with long-acting dry-cow therapy (OR=0.724; 95% CI=0.40–1.30).

CONCLUSIONS AND CLINICAL RELEVANCE: In this herd, which routinely used internal teat sealants, the use of short-acting cloxacillin-based dry-cow therapy did not result in an increased proportion of cows with elevated SSC post-calving. This was a single farm, single year study but indicates that in this herd, changing from a long-acting to a short-acting antimicrobial may have no impact on the prevalence of subclinical mastitis.     

杨树纸浆材优良无性系选择方法的研究

该文利用主成分分析法、遗传距离聚类分析、选择指数和综合性状评分法 ,对 7年生 2 5个杨树无性系进行优良无性系多性状选择 .通过对上述几种方法的比较认为 :遗传距离聚类分析可把无性系分为在主成分值上各具不同特点的类群 ,从而使具有相似特征的无性系归为一类 ,且在优良类群内可以继续选择 ;主成分分析可以评价各无性系综合性状的优劣 ,并作为无性系选择的参考 ;选择指数是评价生长和材性性状较为理想的方法 ;综合性状评分法 ,从选择结果看与前 3种方法结合起来所选的基本一致 ,而且综合性状评分法是一种较为简便、直观的方法 .4种方法共同应用 ,能够较准确地选出生长迅速和材性优良的无性系 .     

秤锤树叶片内生真菌的分离鉴定及其对植株生长的影响

本研究从秤锤树叶片中分离内生菌进行分子鉴定,并接种到无菌组培苗中研究其对植株生长的影响。研究结果显示,从秤锤树叶片中共分离获得7株真菌。扩增出的6个菌株经ITS测序,在NCBI网站上进行基因序列比对,鉴定出其中5株菌株均属于球毛壳菌（Chaetomium globosum）,1株属于子囊菌（As-comycete）。进一步实验表明：分离的菌株多数对组培苗的株高生长影响不大,可初步鉴定其为内生菌,其中的属于球毛壳菌的F和H菌株对无菌苗的株高有明显的促进作用。     

Acute cortisol responses of calves to scoop dehorning using local anaesthesia and/or cautery of the wound

Objective To measure plasma cortisol responses in calves dehorned using a scoop after administration of local anaesthesia and/or cautery of the wounds.
Design A physiological study with controls.
Procedure There were six treatments: control handling with and without local anaesthesia, dehorning, dehorning after local anaesthesia, dehorning followed by wound cautery, and dehorning after local anaesthesia followed by wound cautery. Blood samples were taken before and after dehorning.
Results Dehorning caused an increase in plasma cortisol concentrations, which decreased a little to plateau values and then declined to pretreatment values 3 to 4 h after dehorning. The peak was smaller after local anaesthesia was administered but when its effects wore off, cortisol concentrations increased and thereafter were similar to those in the dehorned animals. The combination of local anaesthesia and cautery resulted in a plasma cortisol response similar to those in control calves with or without local anaesthesia.
Conclusions If plasma cortisol concentrations reflect the distress being experienced by the calves, then local anaesthesia reduces the acute distress for about 3 h after dehorning but not during the subsequent 3 to 4 h. Combining local anaesthetic and cautery prevented the significant increase in plasma cortisol following dehorning and may eliminate the acute distress caused by scoop dehorning.     

Genital pathology of feral male goats

Genitalia from 1000 feral male goats derived from western Queensland and New South Wales were examined after slaughter at an abattoir and the prevalence of abnormalities determined. Ulcerative balanoposthitis, considered due to caprine herpesvirus infection, was observed in 11 animals (1.1%); acidophilic intranuclear inclusions were found in 7 of these. Other conditions included focal hypoplasia of seminiferous tubules in 2 bucks (0.2%), segmental aplasia of the epididymis (one buck, 0.1%), bulbourethral gland cysts with contained aggregations (33 bucks, 3.3%) and haemangiosarcoma of the bulbourethral gland in one animal. The low prevalence of several conditions such as spermatic granuloma, cryptorchidism, and testicular hypoplasia, was attributed largely to the fact that the bucks examined were horned so that the recognised association between genital abnormalities and polledness did not apply.     

荔枝高压苗繁殖技术研究

为提高荔枝高压苗牛根率、成苗率和定植成活率，课题组１９９３至１９９４年在新平县腰街、夏洒白糯格和者新街等地，分别从ＡＢＴ生根粉的应用、母树年龄、母树光照条件和操作技术等方面进行了荔枝高压苗繁殖技术的试验研究。研究结果表明：应用１０００ｐｐｍＡＢＴ１号生根粉处理环剥口能明显缩短压苗的生根时间，提高生根率；进行高压苗繁殖应选用幼龄母树的向阳生枝条和采用效果良好的生根基质，把握好环剥、包扎等操作技术。     

Semen cryopreservation of salmonid fishes: influence of handling parameters on the postthaw fertilization rate

Using the cryopreservation method of Lahnsteiner, Berger, Weismann & Patzner (1995, Aquaculture Research 26 , 801-807) the influence of allowable variations of methodical parameters (storage of semen before cryopreservation, dilution ratios in the extender, equilibration in the extender, cooling rates, storage of deep-frozen semen in liquid nitrogen, storage of frozen/thawed semen, minimal sperm/egg ratio) was investigated under the aspect of routine utilization. Under optimized experimental conditions, fertilization rates were 90-100% of controls in Oncorhynchus mykiss (Walbaum), Salmo trutta L. f. lacustrisSalmo truttaL.f. fario and Salvelinus fontinalis (Mitchill). The following results were obtained: 1. Storage of untreated semen for more than 1 h before cryopreservation decreased the postthaw fertility. 2. Equilibration of semen up to 20 min in the extender did not affect the postthaw fertility. 3. Optimal dilution ratio of semen in the extender was threefold in Oncorhynchus mykiss and Salvelinus fontinalis. Lower dilution ratios decreased the postthaw fertility, higher dilution ratios did not affect the postthaw fertility. In Salmo trutta f. lacustris and Salmo trutta f. fario, which have a higher sperm density, optimal dilution ratio of semen in the extender was fivefold to sevenfold. 4. In Oncorhynchus mykiss, as in Salmo trutta f lacustris and Salmo trutta f. fario, the optimal freezing height was at 1.5 cm above the level of liquid nitrogen (-110 ± 2^oC); in Salvelinus fontinalis it was 2.5 cm above the level of liquid nitrogen (-92 ± 2^oC). Changes in the freezing height of 0.5 cm (about 10^oC) resulted in a significant decrease of postthaw fertility. 5. Storage of deep-frozen semen for up to 370 days in liquid nitrogen had no influence on its postthaw fertilization rate. 6. Storage of frozen/thawed semen for 30 s before insemination significantly decreased its postthaw fertility. 7. Reliable minimal sperm:egg ratio to obtain fertilization rates of 90-100% of control was 3-5 X 10⁵ spermatozoa egg^-1.