Association of herd productivity and bulk-tank somatic cell counts in US dairy herds in 1996     

Ott SL  Novak PR 《Journal of the American Veterinary Medical Association》2001,218(8):1325-1330

OBJECTIVE: To assess the association of bulk-tank somatic cell counts (BTSCC) and the value of herd productivity (milk produced, calves born, and net costs for cow replacements) in US dairy herds in 1996. DESIGN: Randomized stratified national survey of dairy producers. SAMPLE POPULATION: Records from 1,219 dairy herds in the top 20 dairy states. PROCEDURE: Responses for 1,178 herds had complete information for economic analysis. Per-cow value of production was determined for each herd. Data for herds with high (> or = 400,000 cells/ml) and medium (200,000 to 399,999 cells/ml) BTSCC were compared with values for herds with low BTSCC (< 200,000 cells/ml), using a multivariable regression model. RESULTS: In 1996, milk was priced at $0.287/kg ($13/cwt). Herds with low BTSCC annually generated $103.90/cow more in herd productivity than herds with medium BTSCC and $292.39/cow more than herds with high BTSCC. CONCLUSIONS AND CLINICAL RELEVANCE: Increased BTSCC (> 200,000 cells/ml) were associated with a reduced value of productivity per cow. Thus, dairy producers have a financial incentive to seek out and implement cost-effective management practices that will enable them to decrease their BTSCC to < 200,000 cells/ml and maximize herd productivity.  相似文献   

微量矿物质营养调控对生产高品质禽肉影响的研究     

Curtis Novak  Catalina Troche  王强 《中国家禽》2007,29(15):31-33

长期以来家禽养殖者们都是采用一些预防性措施来确保高产、无病害禽产品进入市场.传统意义上,这些预防性措施包括:良好的饲养管理程序、免疫接种程序、适宜的抗菌素添加剂使用和生物安全.……  相似文献   

Untersuchungen über Produktion und Konsum von Honigtau in Hecken Oberfrankens     

Dipl. Biol. H. Novak 《Journal of pest science》1992,65(3):41-48

Zusammenfassung Im Rahmen einer einjährigen Arbeit wurde die Produktion von Honigtau in oberfränkischen Hecken und dessen Nutzung durch die Arthropodenfauna untersucht. Dazu wurde das Artenpektrum und die Phänologie der phloemsaugenden Insekten mit Hilfe der Klopfprobemethode über die gesamte Vegetationsperiode hinweg erfaßt.Von den 25 an den heckentypischen Gehölzarten festgestellten Phloemsaugern traten die Psylliden an Weißdorn und die Aphididen an Schlehe in besonders großen Individuenzahlen auf. Sie stellten im Untersuchungszeitraum die ergiebigsten Honigtauproduzenten in den bearbeiteten Hecken.Die Honigtauabgabe erreichte an den meisten Heckengehölzen ihr Maximum im Frühjahr, mit einem Abklingen in den Sommermonaten und einem erneuten kleineren Anstieg im Herbst. Demgegenüber dauerte die Blattlausentwicklung an der Schlehe und der Eiche den Sommer über an und ermöglichte so ein kontinuierliches Honigtauangebot für nahrungssuchende Insekten über die ganze Vegetationsperiode.An der Schlehe konnten insgesamt 139 Insekternarten als Honigtau-Besucher festgestellt werden. Die Syrphiden waren dabei mit 16 Arten am zahlreichsten vertreten, wobeiEpisyrphus balteatus (Deg.) die mit Abstand häufigste Honigtau-Besucherin stellte.

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Studies on production and consumption of honeydew in hedges of upper frankonia

In a one-year study, the production of honeydew in hedges of Upper Frankonia and its utilization by food-searching insects were investigated. The phloemfeeding fauna and its seasonal development on hedgeshrubs were assessed by means of the beating method.Out of the 25 sap-sucking species recorded on the shrubs typical for hedges, the Psyllidae on hawthorn (Crataegus spec.) and the Aphididae on blackthorn (Prunus spinosa) were most abundant during the period of investigation producing considerable amounts of honeydew.On most hedgeplants honeydew production reached a maximum in spring with a sharp decline in summer and a second but smaller peak in autumn. In contrast, the development of the aphids on blackthorn and oak persisted throughout the summer and therefore there was a continous honeydew supply for foodsearching insect species in the hedges during the season.On blackthorn a total of 139 insect species were recorded taking up honeydew from the plant's surface. In species number as well as in individual number the syrphids were the most frequent honeydew visitors. EspeciallyEpisyrphus balteatus (Deg.) was observed to feed in great numbers on the excretions of aphids.

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Mit 3 Abbildungen und 5 Tabellen  相似文献   

Do the size and landscape context of forest openings influence the abundance and breeding success of shrubland songbirds in southern New England?     

Robert A. Askins  Benjamin Zuckerberg  Leah Novak   《Forest Ecology and Management》2007,250(3):137-147

Early successional birds have declined in the northeastern United States due to the regeneration of forest on abandoned farm fields and the suppression of natural disturbances that once provided appropriate habitat. These species have become increasingly dependent on early successional habitats generated by such activities as timber harvesting. Recent approaches of timber harvesting, which range from single-tree harvesting to clearcutting, create forest openings of different sizes and configurations embedded in landscapes with different land use patterns. To assess the importance of forest openings created by timber harvesting for shrubland birds, we surveyed birds on 50 m radius plots in 34 harvest sites (0.5–21 ha). We collected data on multi-scaled habitat variables ranging from plot-level vegetation characteristics to land use patterns within 1 km of each study site. We also monitored mating and nesting success of Blue-winged Warblers (Vermivora pinus) in 10 forest openings.

The abundance of most shrubland species was influenced by plot-level habitat variables, such as tree density and vegetation height, rather than shrubland area or the composition of land uses in the surrounding landscape. Only Eastern Towhees (Pipilo erythrophthalmus) were more frequent in survey plots in larger forest openings. In contrast, neither abundance nor reproductive activity of Blue-winged Warblers was correlated with the size of the forest opening. Their abundance was negatively related to vegetation height, however. Only 54% of the territorial male Blue-winged Warblers in forest openings were mated. We documented relatively low nest success rates of 21.1% during the egg laying and incubation nest stages, but increased success rates during the later stages of nesting.

Our results indicate that even small forest openings with low vegetation provide habitat for Blue-winged Warblers and other shrubland birds. The overall reproductive rate of territorial male Blue-winged Warblers in forests openings was low during the 2 years of the study, however. Further studies are needed to assess the long-term value of this type of habitat for sustaining shrubland bird populations.  相似文献   

Mangrove expansion and population structure at a planted site,East London,South Africa     

Sabine CL Hoppe-Speer  Anusha Rajkaran 《Southern Forests》2015,77(2):131-139

Avicennia marina (Forrsk.) Vierh. was planted in 1969 at Nahoon Estuary, East London, followed a few years later by the planting of Bruguiera gymnorrhiza (L.) Lam. and Rhizophora mucronata (L.) among the larger A. marina trees. This study tested the hypothesis that mangroves have expanded and replaced salt marsh over a 33-year period (1978–2011). It provides important information on mangroves growing at higher latitudes, where they were thought to not occur naturally due to lower annual average temperatures. It further provides insights on future scenarios of possible shifts in vegetation types due to climate change at one of the most southerly distribution sites worldwide. The expansion of mangroves was measured using past aerial photographs and Esri ArcGIS Desktop 10 software. In addition, field surveys were completed in 2011 to determine the population structure of the present mangrove forest and relate this to environmental conditions. The study showed that mangrove area cover increased linearly at a rate of 0.06 ha y^?1, while the salt marsh area cover also increased (0.09 ha y^?1) but was found to be variable over time. The mangrove area is still relatively small (<2 ha) and expanded mostly over a bare sandflat area. Avicennia marina was the dominant species and had high recruitment (seedling density was 33 822 ± 16 364 ha^?1). Only a few Bruguiera gymnorrhiza and Rhizophora mucronata individuals were found (<10 adult trees), although observations indicate that some young plants are becoming established away from the parent plants. The site provides opportunities for studies on mangrove/salt marsh interactions in response to a changing climate. Mangroves should not be planted in non-native areas as they may become invasive outside their natural range. However, future increases in temperature will certainly lead to a southerly expansion of mangoves in South African estuaries.  相似文献   

Effect of oregano (O. majorana x O. vulgare) on performance and antioxidative capacity of quails fed a diet rich in omega3 fatty acids     

Handl S  Hellweg P  Khol-Parisini A  Rossmann B  Thurner K  Luf W  Novak J  Zentek J 《Journal of animal physiology and animal nutrition》2008,92(3):242-245

Oregano possesses high antioxidant activity and could therefore be used to enhance oxidative stability of eggs high in omega3 fatty acids. In this study, 20 female quails were fed a diet containing 4% linseed oil. They were divided into two groups, one receiving oregano, and the other grass meal as control (2% respectively). Cholesterol oxidation products were analysed in fresh eggs, in stored eggs and in the livers. Trolox equivalent antioxidative capacity of plasma was measured. No significant differences were seen between the groups.  相似文献   

Effects of Interferon‐Tau and Steroids on Cytochrome P450 Activity in Bovine Endometrial Epithelial Cells          下载免费PDF全文

CL Gilfeather  CO Lemley 《Reproduction in domestic animals》2016,51(3):415-420

The objective of the current study was to examine cyclooxygenase (COX), cytochrome P450 1A (CYP1A) and 2C (CYP2C) activity in bovine endometrial cell cultures following exposure to oxytocin (OT), interferon‐τ (IFN), estradiol (E2) and/or progesterone (P4). Bovine endometrial epithelial cells were treated with OT, IFN, a combination of OT+IFN or control (CON) media for 24 h. For the second experiment, cells were treated with E2, P4, a combination of E2 + P4 or CON media for 24 h. Treatments were performed in triplicate, and the experiment was repeated four times (n = 12 per treatment). Treatment with OT alone increased (p < 0.01) activity of COX compared with CON; however, OT alone did not alter activity of CYP1A (p = 0.55) or CYP2C (p = 0.46) compared with CON. Activity of CYP1A and CYP2C was decreased in cells exposed to IFN (p < 0.01) or OT+IFN (p < 0.01) compared with CON. Treatment with E2 alone did not alter activity of CYP1A (p = 0.64) or CYP2C (p = 0.06) compared with CON. Activity of CYP1A and CYP2C was decreased (p < 0.01) in P4 vs CON. In summary, IFN exposure, irrespective of OT treatment, decreased the activity of CYP1A and CYP2C. Activity of CYP1A was decreased following P4 treatment alone, while that of CYP2C was decreased following both P4 and E2 + P4 treatment. The mixed function monooxygenase enzymes, CYP1A and CYP2C, have been implicated in synthesizing embryotoxic compounds; therefore, downregulation in the endometrium may be necessary during maternal recognition of pregnancy.  相似文献   

Induction of Chitinase and β-1,3-Endoglucanase Proteins by UV Irradiation and Wounding in Grapefruit Peel Tissue   总被引：1，自引：0，他引：1  

R. Porat  A. Lers  S. Dori  L. Cohen  B. Weiss  A. Daus  CL. Wilson  S. Droby 《Phytoparasitica》1999,27(3):233-238

UV irradiation enhanced the resistance of grapefruit against the development of green mold décay caused byPenicillium digitatum, the main postharvest pathogen of citrus fruit, and significantly inhibited the fungus’ growth at the fruit wound sites. Immunoblotting analysis using specific citrus chitinase and β-1,3-endoglucanase antibodies, showed that UV irradiation, wounding of the fruit, or a combination of these two treatments, induced the accumulation of a 25 kD chitinase protein in the fruit’s peel tissue. On the other hand, UV irradiation or wounding of the fruit alone was unable to induce the accumulation of 39 and 43 kD β-1,3-endoglucanase proteins, but the combination of the two treatments increased these protein levels. It is suggested that both chitinase and β-1,3-endoglucanase may play a role in the UV-induced resistance of grapefruit againstP. digitatum. Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. No. 403/99. http://www.phytoparasitica.org posting June 3, 1999.  相似文献   

Methods of detection of Chlamydia psittaci in domesticated and wild birds     

CL McELNEA  GM CROSS 《Australian veterinary journal》1999,77(8):516-521

OBJECTIVE: To study the occurrence of Chlamydia psittaci in domesticated and wild birds and compare the sensitivity of molecular detection with cell culture isolation. DESIGN: Study of cell culture isolation and PCR detection of C psittaci in avian samples. PROCEDURE: Samples were obtained from 485 birds. Domesticated birds were selected at random from pet shops, private aviaries and zoos, while wild birds were captured locally, sampled, and immediately released. Swabs were collected from choanal slit, conjunctiva and cloaca of each bird and pooled. Samples were divided into equal portions for use in PCR dot-blot and cell culture detection. PCR and dot-blot detection was based on the ompB gene. RESULTS: Prevalence of infection varied markedly between flocks of captive birds. It was highest where there were frequent changes in the flock members or where there were many birds confined in small areas. C psittaci was not detected in wild birds or water birds. The sensitivity of cell culture compared to PCR dot-blot detection was 68%. All samples positive by cell culture were also positive by PCR. CONCLUSIONS: PCR-dot blot detection of C psittaci in birds appears to be more sensitive than cell culture isolation in this study. C psittaci infection of birds may occur in clinically normal captive birds.  相似文献   

Toward pollen sterility in German chamomile (Matricaria chamomilla)–Conventional breeding approaches of cytoplasmic/genic male sterility and chemical emasculation     

Bettina Faehnrich  Julia Huber  Sarah Wagner  Chlodwig Franz  Beate Fraust  Maria Wehrle  Joana Ruzicka  Johannes Novak  Lars-Gernot Otto 《Plant Breeding》2020,139(6):1299-1309

Pollen sterility (PS) in mother lines is crucial for hybrid crossings in plant breeding. 21 di- (2x) and tetraploid (4x) accessions of the hermaphroditic chamomile were screened for spontaneous, thermic or gametocide induced PS. Two crossing trials with the diploid accessions 'Bona' (BON) and 'Hungary 2' (HUN2) should specify maternally inherited cytoplasmic male sterility (CMS). Progeny thereof showed increased PS. BON as mother (BH) entailed means of 30 and 22% PS, versus 8% and 20% after reciprocal crossings. Backcrosses of BH with HUN2 in paternal and maternal direction revealed increasing mean PS (24% and 32%), without verification of CMS. A split plot design of 100 individuals treated with four chemical gametocides analyzed PS, seed set, germination rate and whole plant damage. Tri-iodobenzoic acid caused the highest PS (43%). Progeny of two plants (2x, 4x) with degenerated anthers without pollen, showed 100% PS either in tetraploid F₁ and F₂ (4% and 11%) or in diploid F₂ and F₃ (26% and 23%). High temperature (30/28°C day/night) decreased the male fertility to some extent.  相似文献