母牛干奶期的缩短(综述)

近来有许多奶牛营养专家和研究人员推荐取消母牛的干奶前期,即延长三周的时间让母牛继续挤奶,然后将母牛直接置于产前35～40天的干奶后期。不断有研究机构表示,少于60天的干奶期对下一泌乳期的产量不存在负面影响。     

Abundance and distribution of the white shark in the Mediterranean Sea

Conservation of apex predators is a key challenge both in marine and terrestrial ecosystems. The white shark is a rare but persistent inhabitant of the Mediterranean Sea and it is currently assessed as “critically endangered” in the region. However, the population trends and dynamics of this species in the area are still unknown. Little is known about white shark distribution, habitat use and population abundance trends, aspects that are critical for conservation and management. In this study, we built the most comprehensive database of white shark occurrence records in the region. We collected 773 different records from different sources and used them to characterize the spatial and temporal patterns of abundance of Mediterranean white sharks between 1860 and 2016. We analysed these data by using generalized additive models and used spatially disaggregated information on human population abundance as a proxy of observation effort. Our results suggest a complex trajectory of population change characterized by a historical increase and a more recent reduction (61%, range 58%–72%) since the second half of the 20th century. In particular, analyses reveal a 52% (range 37%–88%) to 96% (range 92%–100%) overall decline in different Mediterranean sectors and a contraction in spatial distribution. Here, we provide the first reconstruction of abundance trends and offer new hypotheses regarding the drivers of change of white sharks in the Mediterranean. Our approach can be broadly applied to data‐poor contexts to reconstruct change and inform the conservation of endangered top predators in the Mediterranean Sea and other intensely used marine regions.     

Influence of temperature and oxygen on the distribution of blue marlin (Makaira nigricans) in the Central Pacific

The blue marlin (Makaira nigricans) is a highly migratory pelagic predator of tropical and subtropical seas. Information on the habitat use of marine species is fundamental to understanding their ecology and population dynamics and is needed to inform responsible management strategies. Using a long‐term satellite tagging data set from The International Game Fish Association Great Marlin Race, we examined habitat use and how oxygen and temperature influence the horizontal and vertical distributions of blue marlin in the Central Pacific. Blue marlin primarily occurred in warm waters (26–30°C) and exhibited a diel bimodal depth distribution across the 5‐year data record (2009–2013), with fish spending the majority of their time near the surface at night and at deeper depths during the day (25–100 m). The depth distribution of blue marlin was limited in areas where low oxygen and/or temperature conditions occur closer to the surface, with the extent of habitat compression being greatest when both oxygen and temperature were limiting. The migrations of blue marlin appeared restricted during the 2010 La Niña, when increased equatorial upwelling resulted in an extension of the cold, low oxygen waters of the cold tongue into the Central Pacific, creating a barrier to the trans‐equatorial migrations that occurred during all other tagging years. If the frequency and intensity of La Niña events increases and the oxygen minimum layer continues to expand as has been predicted under certain climate change scenarios, the migratory behavior and habitat availability of blue marlin may be impacted.     

Treatment of feline leukemia virus (FeLV) infection.

FeLV infection is still considered to account for most disease-related deaths in pet cats. Different treatment attempts with various drugs were performed in the past but none resulted in healing or complete virus elimination. Therefore, it caused a sensation when Horber and Mayr [Horber, D., Mayr, B., 1991. Prax. 19, 311-314; Horber, D., Schnabl, W., Mayr, B., 1992. Tierarztl. Umschau 47, 556-560; Mayr, B., Horber, D., 1992. Kleintierprax. 37, 515-518] published that they were able to cure 80 to 100% FeLV-infected cats from viremia by using an immunomodulating compound. Articles in cat breeder and cat owner journals appeared assuming that obviously there is a rescue for FeLV-infected cats suffering from this deadly infection. The immunomodulator [Buttner, M., 1993. Comp. Immun. Microbiol. Infect. Dis. 18, 1-10] used in those studies was the so-called 'paramunity inducer' PIND-ORF (Baypamun, Bayer, Leverkusen, Germany) consisting of inactivated parapox ovis virus. Since that time, Baypamun is the most commonly used drug for treatment of FeLV infection in Germany and other European countries. Four placebo-controlled double-blind trials were performed to determine the therapeutic efficacy of Baypamun and other compounds in naturally FeLV-infected cats under controlled conditions.     

Migratory movements, depth preferences, and thermal biology of Atlantic bluefin tuna

The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of >1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic.     

Natal homing and connectivity in Atlantic bluefin tuna populations

Atlantic bluefin tuna populations are in steep decline, and an improved understanding of connectivity between individuals from eastern (Mediterranean Sea) and western (Gulf of Mexico) spawning areas is needed to manage remaining fisheries. Chemical signatures in the otoliths of yearlings from regional nurseries were distinct and served as natural tags to assess natal homing and mixing. Adults showed high rates of natal homing to both eastern and western spawning areas. Trans-Atlantic movement (east to west) was significant and size-dependent, with individuals of Mediterranean origin mixing with the western population in the U.S. Atlantic. The largest (oldest) bluefin tuna collected near the northern extent of their range in North American waters were almost exclusively of western origin, indicating that this region represents critical habitat for the western population.     

Refining Inclusion Levels of Grain Distiller's Dried Yeast in Commercial‐type and Plant‐based Diets for Juvenile Rainbow Trout,Oncorhynchus mykiss

Recent studies with rainbow trout, Oncorhynchus mykiss, demonstrated that grain distiller's dried yeast (GDDY) at up to 12% inclusion was an effective dietary protein source when replacing fish meal. To examine the effectiveness of GDDY when replacing an increased variety of dietary protein sources, two feeding trials were conducted. In the first trial, six commercial‐type diets were formulated to contain 42% digestible protein and 20% crude lipid with GDDY included at 0, 6, 9, 12, 15, and 18% to replace all dietary protein sources except fish meal. In the second trial, four plant‐based diets with GDDY at 0, 9, 12, and 15% were examined. Experimental diets were fed twice daily, to apparent satiation, to three replicate tanks of fish/diet (initial weight = 22.3 ± 0.7 g) for 10 wk in a 15 C recirculating system. Results demonstrated excellent fish growth and the inclusion rate of GDDY did not negatively affect growth or feed conversion. No significant negative effects of GDDY on body indices or whole‐body proximate composition were observed. Based on these results, GDDY can be included in both commercial‐type diets and plant‐based diets for rainbow trout at up to 18 or 15%, respectively, without decreasing growth performance.     

Mechanized land preparation in forest-based fallow systems: The experience from Eastern Amazonia

Agroforestry Systems - The slash-and-burn practice of land preparation that farmers use traditionally in forest-based fallow systems in the humid tropics causes land degradation and human health...     

Productivity of mixed versus pure stands of oak (Quercus petraea (Matt.) Liebl. and Quercus robur L.) and European beech (Fagus sylvatica L.) along an ecological gradient

The mixture of beech (Fagus sylvatica L.) and oak (sessile oak, Quercus petraea (Matt.) Liebl., and pedunculate oak, Q. robur L.) is of considerable importance in Europe and will probably become even more important under climate change. Therefore, the performance of oak and beech in mixture was compared with the species’ growth in pure stands. Data from 37 long-term mixing experiments in Poland, Germany and Switzerland were pooled for analysis of mixing effects on stand productivity and possible interrelationships with mixing portions or site conditions. We found that on average, mixed stands of oak and beech exceeded biomass productivity in pure stands by 30 % or 1.7 t ha^?1 year^?1, as the growth of both species was benefitted by the mixture. However, that the interaction actually ranged from facilitation and overyielding on poor sites to underyielding on fertile sites triggered by competition. An empirically derived interaction model showed volume and dry mass growth changing in mixed stands from gains of 50 % to losses of 10 % depending on site conditions. It is concluded that the analysed mixture grows in accordance with the stress-gradient hypothesis and that our results suggest a site-specific relationship between species mixture and biomass productivity. As a consequence, an adequate species mix should result in increased productivity under steady state as well as climate change.