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.     

基于无线传感器网络的奶牛行为特征监测系统设计

奶牛等大型动物的疾病和发情状况目前主要依赖饲养员目测判断,大规模集约化养殖仍采用人工观测方法,这不仅带来繁重的人力负担,也容易误判。为了能自动准确地识别奶牛是否发情或生病,该文提出在奶牛颈部安装无线传感器节点,通过各种传感器获取奶牛的体温、呼吸频率和运动加速度等参数,采用K-均值聚类算法对提取的各种参数进行行为特征多级分类识别,以此建立的动物行为监测系统能准确区分奶牛静止、慢走、爬跨等行为特征,从而可以长时间监测奶牛的健康状态。而且,这种监测系统易于推广到对其他动物的监测,对促进养殖业和畜牧业的发展也具有指导意义。     

Rearing Macrobrachium rosenbergii larvae in Fiji

Rearing Macrobrachium rosenbergii larvae to post-larvae has been accomplished using simple techniques. Live Artemia nauplii, ground kai meat (Batissa violacea) and tuna (Thunnus albacores) were used as food. About 16 300 post-larvae were produced in 13 trials.     

Dimensionality-driven insulator-to-metal transition in the bechgaard salts

Optical experiments were conducted on a series of organic linear chain conductors with different values of the interchain single-electron transfer integral tb, which quantifies the degree of anisotropy. Electron-electron interactions together with Umklapp scattering resulted in a correlation gap and an insulating state for small tb. An insulator-to-metal transition was observed when tb exceeded a critical value, on the order of the correlation gap Egap. The absence of a plasma edge on the insulator side of the transition for polarization perpendicular to the chains suggests that the electrons are confined to the chains. The optical features of the metallic state, when contrasted with the magnetic properties, are suggestive of spin-charge separation.     

Effects of elevated dietary iron on the gastrointestinal expression of Nramp genes and iron homeostasis in rainbow trout (Oncorhynchus mykiss)

Diet is the primary source of iron (Fe) for freshwater fish, and the absorption of Fe is believed to occur via the Nramp family of divalent metal transporters (also called DMT1). Presently, the homeostatic regulation of dietary Fe absorption in fish is poorly understood. This study examined the gastrointestinal mRNA expression of two Nramp isoforms, Nramp-β and Nramp-γ, in the freshwater rainbow trout (Oncorhynchus mykiss), following exposure to elevated dietary Fe [1,256 mg Fe/kg food vs. 136 mg Fe/kg food (control)] for 14 days. The physiological performance, plasma Fe status and tissue-specific accumulation of Fe were also evaluated. In general, the mRNA expression level of Nramp was higher in the intestine relative to the stomach. Interestingly, fish fed on a high-Fe diet exhibited a significant induction in Nramp expression after 7 days, followed by a decrease to the level observed in control fish on day 14. The increase in Nramp expression correlated with the elevated gastrointestinal and plasma Fe concentrations. However, the hepatic Fe concentration remained unchanged during the entire exposure period, indicating strong homeostatic regulation of hepatic Fe level in fish. Fish appeared to handle increased systemic Fe level by elevating the plasma transferrin level, thereby enhancing the Fe-binding capacity in the plasma. Overall, our study provides new interesting insights into the homeostatic regulation of dietary Fe uptake and handling in freshwater fish.     

Benefits of Conservation Agriculture on Soil and Water Conservation and Its Progress in China

Conservation agriculture has been practised for three decades and has been spread widely. There are many nomenclatures surrounding conservation agriculture and differ to each other lightly. Conservation agriculture (CA) is a system approach to soil and water conservation, high crop productivity and profitability, in one word, it is a system approach to sustainable agriculture. Yet, because conservation agriculture is a knowledge-intensive and a complex system to learn and implement,and also because of traditions of intensive cultivation, adoption rates have been low, since to date, only about seven percent of the world's arable and permanent cropland area is farmed under conservation agriculture. The practice and wider extention of conservation agriculture thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to conserve soil and water and improve sustainability over the long term. This paper described terms related to conservation agriculture, presented the effects of conservation agriculture on soil and water conservation, crop productivity, progress and adoption of CA worldwide, emphasized obstacles and possible ways to increase CA adoption to accelerate sustainable development of China agriculture.     

Impact of the use of biofertilizers on cotton ( Gossypium hirsutum ) crop under irrigated agro-ecosystem

High nitrogen fixing, phosphate solubilizing, phytohormones producing isolates of Azotobacter, Azospirillum, Acetobacter and Pseudomonas were used as inoculants for cotton. Important cultures were selected on the basis of their effect on root/shoot length and chemotactic behaviour. Selected bioinoculants were earlier tested for their beneficial properties like nitrogen fixation (ARA), ammonia excretion, IAA production etc. These bio-inoculants were further tested for phosphate solubilization property. Various chosen strains were tested with Desi (HD 123) and American (H 1098) cotton under field conditions (as for wheat). Plant height and boll weight were determined at the time of harvesting whereas survival rate of inoculated bacteria was determined after 30, 80 and 130 days respectively. In the year 2000–01, on the basis of boll number and boll weight plant^?1 AVK 51 (36; 76.2?g plant^?1), HT 57 (27; 56.9?g plant^?1), AC18 (33; 61.5?g plant^?1), Ala 27 (36; 61.4?g plant^?1) and Pseudomonas (34; 71.3?g plant^?1) were identified as significant both for American and desi cotton varieties. Highest survival rate was observed with Mac 68 (33.4 × 10⁵) followed by HT54 (31.5 × 10⁵) after 30 days of sowing, which decreased after 80 days and remained constant up to 130 days. This trend was observed with all the cultures. Similar results were observed in 2001–02. 25?kg ha^?1 N saving was observed with A. chroococcum (AVK51) bioinoculant for cotton crop.