Comparison of crossbred cows containing various proportions of Brahman in spring- or fall-calving systems: IV. Effects of genotype x environment interaction on lifetime productivity of young cows.     

M N McCarter  D S Buchanan  R R Frahm 《Journal of animal science》1991,69(10):3977-3982

Lifetime productivity of young (2 to 6-yr-old) crossbred cows containing various proportions (0, 1/4, or 1/2) of Braham breeding was evaluated using 188 spring-calving and 154 fall-calving cows. Cows were mated to Limousin sires to produce 1983 through 1986 calf crops. The 1987 calf crops were produced using Limousin and Salers sires. Significant (P less than .10) genotype (crossbred cow group) x environment (season of calving) interactions were found for age at first calf and lifetime calving percentage and mature cow weight. Within the spring calving group, no differences were found between crossbred groups for age at first calf or lifetime calving percentage. However, within the fall-calving group, 0 and 1/2 Braham cows from Angus dams calved earlier than did those from Hereford dams. Age at first calf also tended to increase as proportion of Brahman increased in the fall-calving group. Within the fall-calving group, lifetime calving percentage for 0 and 1/2 Brahman cows from Hereford dams was lower than for those from Angus dams. The opposite was true for the 1/4 Braham crosses. In general, as the proportion of Brahman breeding increased, productivity, measured as weight per calf or weight weaned per year, increased; however, age at first calving increased also as proportion of Brahman increased. All spring-calving groups calved earlier in life (P less than .05) than their respective fall-calving counterparts and with the exception of the 0 Brahman groups, which were similar, spring-calving groups produced a higher (P less than .05) percentage of calves than did the fall groups.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Composition of rumen contents and digestion as related to the type of feed and time of sampling in sheep     

D O Erickson  W E Dinusson  D W Bolin  C N Haugse  M L Buchanan 《Journal of animal science》1970,30(2):262-267

  相似文献   

Relationship of gastrointestinal histology and mucus antiparasite activity with the development of resistance to trichostrongyle infections in sheep     

P. G. C. Douch  G. B. L. Harriston  D. C. Elliott  L. L. Buchanan  K. S. Greer 《Veterinary parasitology》1986,20(4):315-331

Changes in the numbers of globule leucocytes, mast cells, eosinophils and goblet cells in the gastrointestinal mucosa were examined in relation to the development of resistance and elimination of nematodes in grazing sheep in their firsty year of life. Sheep immunised against Trichostrongylus colubriformis, and sheep treated with dexamethansone were also examined. A strong association between resistance to infection and the presence of globule leucocytes was found. In contrast, the numbers of mast cells or goblet cells were not correlated with resistance. Globule leucocyte and eosinophil numbers were also correlated with antiparasite activity in mucus.

Immunising infections of T. colubriformis given to 10-month-old sheep, their duration limited by thiabendazole treatment, gave rise to considerable immunity to homologous challenge infections. Larvae that developed to the 4th stage were as effective at stimulating immunity as those that developed to the 5th stage. Dexamethasone treatment abrogated resistance to trickle challenge infection with T. colubriformis and reduced mucosal globule leucocyte and mast cell numbers. After cessation of drug treatment, the re-establishment of resistance and adult worm elimination were associated with repopulation of the mucosa with large numbers of globule leucocytes and high antiparasite activities in mucus.  相似文献   

Aortic embolism in cats: prevalence, surgical treatment and electrocardiography   总被引：2，自引：0，他引：2  

J W Buchanan  G J Baker  J D Hill 《The Veterinary record》1966,79(18):496-505

  相似文献   

Projection Slides in 90 Seconds1     

James W. Buchanan 《Veterinary radiology & ultrasound》1977,18(2):58-69

  相似文献   

Altruism is rewarding   总被引：2，自引：0，他引：2  

R F Weiss  W Buchanan  L Altstatt  J P Lombardo 《Science (New York, N.Y.)》1971,171(977):1262-1263

People will learn an instrumental conditioned response, the reward for which is the deliverance of another human being from suffering.  相似文献   

Morphological variants developing in L-form cultures of two strains of Actinomyces spp. of canine origin     

Audria M. Buchanan 《Veterinary microbiology》1982,7(6):587-605

The present study has shown that a catalase-positive Actinomyces-like organism, UCD 19-480, failed to grom from its clinical fluid origin as normal colonies on three types of L-form media, although all three media were later shown to support it from a blood agar plate source. The growth of 19-480 from a fresh sulfur granule into a droplet of modified Barile Yaguchi Eveland (BYE) L-form broth was studied in a sealed slide incubated at 25–28°C for 11 weeks. Within 7 days, very long, bizarre branched filaments were detected near the crushed granule mass. Microcolonies were present at 5 weeks with radial filaments extending 0.5 cm from a core. The core consisted of pleomorphic vesicles arranged in a ring. Crystals appeared within and around the granule, but not elsewhere. After repeated passage on blood agar plates, 19-480 and a second, non-granule strain of recent origin, 339-180, were inoculated into BYE L-form broths as well as broths of new design. Unique membranous structures exhibiting actinomycete morphology were detected at 3 weeks in the 19-480 trypticase soya cultures containing putrescine and at 9 weeks in BYE L-form broths. They were restricted to the deep portions of certain broth types at predictable times and were not present in incubated controls. They fluoresced intensely with acridine orange and were weakly Gram-positive. ‘Pseudocolony’-like formations were detected at 8 weeks in the 3% NaCl + 5% sucrose BYE broth culture of UCD 19-480. It is suggested that the absence of normal colonies of these agents of L-form plate cultures of clinical fluids is due to growth of spreading variants unique to the actinomycete group.  相似文献   

Distribution, density and abundance of the western Baltic herring (Clupea harengus) in the Sound (ICES Subdivision 23) in relation to hydrographical features     

J. Rasmus Nielsen  Bo Lundgren  Torben F. Jensen  Karl-Johan Sthr 《Fisheries Research》2001,50(3):235-258

Biomass and duration of the over-wintering period of the Rügen spring spawning herring stock (RHS) in the Sound (ICES Subdivison 23) were investigated as well as possible hydrographical factors affecting relative distribution and triggering southwards migration towards the spawning grounds. Monitoring was performed during 27 surveys over a 6-year period (1993–1998). Abundance of 45–165 000 t in August–February, 5–60 000 t in March–May, and <2000 t in June–July was found. This indicates a longer over-wintering period than hitherto assumed. The year classes 1988, 1991 and 1994 were relatively strong occurring in the Sound from age 2 (winter-rings) and abundance in autumn 1993 and 1996–1997 was relatively high. Relative year class strengths are in accordance with variations in larval indices at the spawning grounds. Decreasing abundance in late spring in the Sound was concordant with observed peaks in commercial landings and (subsequent) peak larval indices at the spawning grounds. Larger size groups seem to migrate southwards in spring before smaller herring size groups. Peak herring densities occur in the northern Sound in autumn and they do not concentrate near the southern Drogden threshold in spring before southwards spawning migration. Highest densities were found from 8 to 22 m below sea surface, and just below or in the halocline in areas with stratified water column. Indications of inflows to the Baltic triggering southwards migration can be observed at some occasions, however, these results are not conclusive because of relatively few biomass estimates in 1996–1998. The identified patterns in herring occurrence agree with some conclusions on migration routes for RHS from previously reported tagging studies, but the present investigations indicate prolonged over-wintering in the Sound. This report quantifies the abundance and distribution of herring in the Sound over the year on basis of repeated investigations, and investigates possible influence of hydrographical factors on distribution and migration.  相似文献   

Implementing the precautionary approach into fisheries management: Biomass reference points and uncertainty buffers     

Tobias K. Mildenberger  Casper W. Berg  Alexandros Kokkalis  Adrian R. Hordyk  Chantel Wetzel  Nis S. Jacobsen  Andr E. Punt  J. Rasmus Nielsen 《Fish and Fisheries》2022,23(1):73-92

The precautionary approach to fisheries management advocates for risk-averse management strategies that include biological reference points and account for scientific uncertainty (i.e. process, model and observation uncertainty). In this regard, two approaches have been recommended: (a) biomass reference points to safeguard against low stock biomass, and (b) uncertainty buffers that reduce the catch limit as a function of the scientific uncertainty. This study compares the effectiveness of these two precautionary approaches in recovering over-exploited fish stocks. We evaluate the performance of more than 80 harvest control rules (HCRs) within a stochastic management strategy evaluation (MSE) framework for three stocks with contrasting life-history parameters and under various levels of scientific uncertainty. The results show that both approaches reduce the risk of overfishing at the expense of expected yield. This risk-yield trade-off strongly depends on the HCRs, life-history parameters of the species, as well as the level of the scientific uncertainty. Nevertheless, some combinations of biomass threshold and limit reference points as well as uncertainty buffers lead to a more favourable risk-yield trade-off than other rules. This study elucidates the multiple factors affecting the effectiveness of management strategies and highlights key features of HCRs for precautionary fisheries management.  相似文献   

Prolonged activation of mitochondrial conductances during synaptic transmission     

Jonas EA  Buchanan J  Kaczmarek LK 《Science (New York, N.Y.)》1999,286(5443):1347-1350

Although ion channels have been detected in mitochondria, scientists have not been able to record ion transport in mitochondria of intact cells. A variation of the patch clamp technique was used to record ion channel activity from intracellular organelles in the presynaptic terminal of the squid. Electron microscopy indicated that mitochondria are numerous in this terminal and are the only organelles compatible with the tips of the pipettes. Before synaptic stimulation, channel activity was infrequent and its conductance was small, although large conductances ( approximately 0.5 to 2.5 nanosiemens) could be detected occasionally. During a train of action potentials, the conductance of the mitochondrial membrane increased up to 60-fold. The conductance increased after a delay of several hundred milliseconds and continued to increase after stimulation had stopped. Recovery occurred over tens of seconds.  相似文献