Long- and short-term flooding effects on survival and sink-source relationships of swamp-adapted tree species     

Angelov MN  Sung SJ  Doong RL  Harms WR  Kormanik PP  Black Jr CC 《Tree physiology》1996,16(5):477-484

About 95% of swamp tupelo (Nyssa sylvatica var. biflora (Walt.) Sarg.) and sweetgum (Liquidambar styraciflua L.) seedlings survived continuous root flooding for more than two years, whereas none of the swamp chestnut oak (Quercus michauxii Nutt.) and cherrybark oak (Q. falcata var. pagodifolia Ell.) seedlings survived one year of flooding. Death of oak seedlings occurred in phases associated with periods of major vegetative growth, e.g., after bud burst in spring, after summer stem elongation, and during the winter deciduous stage, suggesting that stored reserves and sources were inadequate to maintain the seedlings when vegetative sinks were forming. Additional evidence that flooding induced a source deficiency in oak was that leaves of flooded oak were 65 to 75% smaller than leaves of nonflooded oak. Flooded swamp tupelo seedlings had a normal leaf size and patchy stomatal opening compared with nonflooded seedlings. Flooding caused increases in alcohol dehydrogenase (ADH) specific activity in taproot cambial tissues and increases in starch concentrations of swamp tupelo seedlings that were reversed when seedlings were removed from flooding. Flooding had little effect on soluble sugar concentrations in swamp tupelo or sweetgum. In the long-term flood-dry-flood treatment, in which all species had survivors, upper canopy leaf photosynthetic rates were higher in all species during the dry period than in nonflooded controls, whereas their starch and soluble sugars concentrations were similar to those of nonflooded controls. Based on seedling survival and the sink-source relationships, the order of flood tolerance was: swamp tupelo > sweetgum > swamp chestnut oak > cherrybark oak.  相似文献   

Effects of white-tailed deer on vegetation structure and woody seedling composition in three forest types on the Piedmont Plateau     

C. Reed Rossell  Jr.  Bryan Gorsira  Steven Patch 《Forest Ecology and Management》2005,210(1-3):415-424

White-tailed deer (Ododcoileus virginiana) can substantially affect the structure and species composition of a forest. The tolerance of a forest community to browsing may vary by type as a result of varying biotic and abiotic factors of the environment. To date, no studies have compared the effects of browsing among forest communities within a physiographic region. We investigated the effects of browsing on vegetation structure and woody seedling composition in three forest types (oak–hickory, Virginia pine–eastern red cedar, bottomland hardwood) in Manassas National Battlefield Park (MNBP), Virginia, USA. We compared forb cover, vertical plant cover (0–1.5 m tall), and survival of tagged seedlings in 10 exclosed (2 m × 6 m) and 10 unexclosed plots in each forest type during a 5-year period. No differential effects of browsing were found among forest types. In all forest types, deer (67 deer/km²) suppressed forb and vertical plant cover to levels less than would be expected in the absence of deer. Seedling survival rates of most species were significantly reduced by browsing. By the 4th year of the study, box elder (Acer negundo), hickory (Carya spp.), and red maple (Acer rubrum) had been eliminated from unexclosed plots, and red and white oaks (Quercus spp.) dramatically reduced. Ash (Fraxinus spp.), black cherry (Prunus serotina), and hackberry (Celtis occidentalis), although significantly impacted, remained the most abundant species throughout the study. These findings suggest that white-tailed deer may be modifying the structure of the forest interior to the extent that it adversely affects wildlife species dependent on a dense understory to thrive. We predict that the future composition of forests in MNBP will shift towards stands with fewer species and a greater dominance of ash, black cherry, and hackberry, particularly in the oak–hickory and bottomland hardwood forests, where the majority of current dominants are most affected.  相似文献   

Status of the genetic diversity and population structure of the Pêga donkey     

Mário Luiz Santana Jr.  Annaiza Braga Bignardi 《Tropical animal health and production》2015,47(8):1573-1580

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Clinical,histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses          下载免费PDF全文

Nelson I. Pinto  Richard J. McMullen Jr.  Keith E. Linder  John M. Cullen  Brian C. Gilger 《Veterinary ophthalmology》2015,18(6):443-456

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Methane emissions and δ13C composition from beef steers consuming increasing proportions of sericea lespedeza hay on bermudagrass hay diets     

Flavia O S van Cleef  Jos C B Dubeux  Jr.  Harley D Naumann  Erick R S Santos  Lynn E Sollenberger  Joo M B Vendramini  Martin Ruiz-Moreno  Francine M Ciriaco  Nicolas DiLorenzo 《Journal of animal science》2021,99(8)

An experiment was conducted to evaluate the effects of different proportions of ‘Au Grazer’ sericea lespedeza [SL, Lespedeza cuneata (Dum. Cours.) G. Don], a legume rich in condensed tannins (CT), on nutrient intake and digestibility, and to estimate methane (CH₄) emissions and ¹³C isotopic composition (δ¹³C_CH4) from beef steers consuming a forage-based diet. Twenty-five Angus-crossbred steers were distributed in a randomized complete block design (344 ± 48 kg initial BW), and randomly assigned to one of five treatments: 0SL, 25SL, 50SL, 75SL, and 100SL, diets containing 0%, 25%, 50%, 75%, and 100% of SL hay, respectively, mixed with ‘Tifton-85’ bermudagrass hay (Cynodon spp.). The study was carried out for two experimental periods of 21-d each. The statistical model included the fixed effect of treatment and random effects of block, experimental period, and their interaction. Apparent total tract digestibility of crude protein, neutral detergent fiber, and acid detergent fiber was linearly decreased (P < 0.001) by the inclusion of SL. No effects were observed for total CH₄ emissions per day, nor for CH₄ relative to organic matter intake or digestible organic matter with the inclusion of SL. However, emission of CH₄ in relation to intake of CT was affected by treatment (P < 0.001). A linear (P < 0.001) decrease and a quadratic effect (P < 0.001) were observed for δ¹³C of diets and gas, respectively, in which diets and enteric CH₄ with greater inclusion of SL were more depleted in ¹³C. Moreover, the difference in δ¹³C between diets and gas (Δδ¹³C) had a linear decrease (P = 0.001) with the inclusion of SL. The model developed to predict the C₃ proportions in the enteric CH₄ fitted to predicted values (P < 0.0001). Therefore, greater proportions of SL resulted in lesser CH₄ emission when CT intake was considered and the isotopic composition from enteric CH₄ was able to predict the contribution of SL in the emissions.  相似文献   

Marine shrimp aquaculture: a novel waste treatment system     

C. S. Lee  J. N. Sweeney  W. K. Richards  Jr. 《Aquacultural Engineering》1986,5(2-4):147-160

Ecuadorian Penaeus vannamei were cultured in dirt ponds (each of approximately 163 m²) at four different stocking densities, i.e. 5 shrimp m⁻², 10 shrimp m⁻², 15 shrimp m⁻² and 20 shrimp m⁻². Experiments were carried out over three different periods during the year. Each experiment lasted for 11–14 weeks. No commercial feed was given to the shrimp. The only input to the ponds was about 30 kg of cattle manure per pond per week. Chemical composition of the cattle manure was analyzed. Water quality parameters such as temperature, pH, DO and turbidity were recorded twice daily for each experiment; nutrients (nitrite, nitrate, ammonium and phosphate), water ATP, sediment ATP, H₂S and chlorophyll were measured twice weekly for each experiment. Shrimp were sampled either weekly or bi-weekly for body weight measurements.

The results showed a negative correlation between stocking density and growth. Weekly growth ranged from 0·44 to 1·58 g week⁻¹. Survival was over 50% in all treatments and averaged at 70·8%. Under these stocking densities, shrimp production ranged from 4·4 to 18·8 kg ha⁻¹ day⁻¹. The stocking density of 15 shrimps m⁻² provides better production than the other stocking densities.

Water quality data did not relate to any shrimp growth. Water nutrient levels in pond discharge water were less than or equal to the nutrients in the incoming water in spite of the weekly addition of cattle manure and did not increase with the addition of cattle manure. No coliform bacteria were detected in any pond water samples through the study period. This indicates digestion of cattle manure in marine shrimp ponds would not pollute the environment with high concentrations of dissolved nutrients.

Thus, a marine shrimp pond can be considered a dissolved nutrient marine treatment plant converting unwanted cattle manure (1841 kg cattle manure ha⁻¹ week⁻¹ in this study) into a valuable commodity — shrimp.  相似文献   

Short-wave solar radiation level willingly tolerated by lactating Holstein cows in an equatorial semi-arid environment     

Steffan Edward Octávio Oliveira  Cíntia Carol de Melo Costa  João Batista Freire de Souza Jr  João Paulo Araújo Fernandes de Queiroz  Alex Sandro Campos Maia  Leonardo Lelis de Macedo Costa 《Tropical animal health and production》2014,46(8):1413-1417

The amount of short-wave solar radiation willingly tolerated by lactating Holstein cows on pasture was determined in an equatorial semi-arid environment. The study was carried out on a dairy farm located in Limoeiro do Norte, CE, northeastern Brazil. The observed behaviours were as follows: grazing, under the sun, under the shade, standing, lying, ruminating, idling and wallowing in the water. The behaviours were recorded using instantaneous scan sampling at regular intervals of 15 min from 0600 to 1800 hours over 5 days. On all sampling days, the meteorological variables, including local short-wave solar radiation (R _S-W, W m^?2), were recorded. The R _S-W data were divided into five levels. The sun exposure was more frequent under low (100 %) and moderately low (97 %) levels, when R _S-W remained below 500 W m^?2. The grazing was more intense under low (100 %) and moderately low (93 %) levels. Above 500 W m^?2, the grazing time significantly decreased (11 %). The cows avoided grazing under high (0 %) and very high (0 %) levels, when R _S-W exceeded 700 W m^?2. The ruminating behaviour was more frequent under high (33 %) and very high (37 %) levels, in which the highest averages of R _S-W were recorded (815 and 958 W m^?2, respectively). The standing posture was more frequent under low (100 %) and moderately low (97 %) levels. Therefore, the critical R _S-W level that motivates cows to stop grazing and seek shade was in the interval between 500 and 700 W m^?2.  相似文献   

Effect of the replacement of Tifton 85 with maniçoba hay on the performance of Morada Nova hair sheep     

Dorgival Morais de Lima Jr.  Francisco Fernando Ramos de Carvalho  Maria Norma Ribeiro  Ângela Maria Vieira Batista  Bárbara Ferraz Ferreira  Paulo de Barros Sáles Monteiro 《Tropical animal health and production》2014,46(6):995-1000

The use of native and adapted forages is an alternative for sustainable production systems in northeast Brazil. The goal of this study was to evaluate the substitution of Tifton 85 by maniçoba hay on the performance and carcass traits of Morada Nova hair sheep. The 16 lambs that were used in this study initially weighed 19.36?±?1.48 kg, were housed in individual pens, and were slaughtered at 58 days of confinement. The dry matter intake (839.84 g/day and 3.81 % WB) was higher (P?<?0.05) in sheep fed maniçoba hay. The feed conversion was 7.39 for sheep fed maniçoba hay. The empty body weight (21.61 kg) and cold carcass weight (11.40 kg) did not differ (P?>?0.05) between sheep fed different hay types. The replacement of Tifton 85 by maniçoba hay did not influence the loin eye area (cm²) or carcass compactness index (kg/cm). The replacement of Tifton 85 by maniçoba hay in Morada Nova sheep diet did not affect the weight gain or carcass characteristics. The maniçoba hay can be considered a forage resource for feeding sheep in Brazilian semiarid tropics.  相似文献   

Atypical fibrosarcoma in the skin of a Roborovski hamster (Phodopus roborovskii)     

James G. Johnson III  Robert Blair  João Brandão  Thomas N. Tully Jr  Stephen D. Gaunt 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2014,43(2):281-284

A 2.5‐year‐old intact male Roborovski hamster (Phodopus roborovskii) was presented with a large subcutaneous mass overlying the abdomen, affecting the animal's ambulation and access to different compartments of the cage through narrow tubing. Ultrasound examination delineated a well‐circumscribed mass in the subcutis of the caudoventral abdominal region. The mass was surgically excised and on cytologic examination showed, in a background of blood, a small population of individually arranged oval to spindle‐shaped cells that exhibited a moderate degree of anisokaryosis, coarsely stippled chromatin, one or more prominent nucleoli, and lightly basophilic well‐defined cytoplasmic processes. Histologically, the mass was composed of interlacing streams and bundles of pleomorphic spindle cells (ganglion‐like cells) with variable amounts of collagenous stroma. The neoplastic cells exhibited moderate features of malignancy. These cells stained intensely with vimentin, but not with any other markers, including antibodies to cytokeratin AE1/AE3, S100 protein, desmin, smooth muscle actin, synaptophysin, neurofilament, and androgen receptor. Based on histologic features, the mass was diagnosed as an atypical fibrosarcoma. This is the first report of an atypical fibrosarcoma in a Roborovski hamster and one of few reports of atypical fibrosarcoma in domesticated hamsters overall.  相似文献   

Acupuncture Diagnosis in Equine Stifle Disease     

Pedro V. Michelotto Jr.  Luis F.C. BastosCristina S. Sotomaior  DVM  PhD  Cláudia T. Pimpão  DVM  PhD 《Journal of Equine Veterinary Science》2014

The stifle is a large and complex joint in quadrupeds, including horses, making the diagnosis of stifle diseases a challenge for the clinician. The detection of “stifle syndrome” during acupuncture examination of the equine stifle may be useful for diagnosis of stifle diseases in horses. The aim of the present study was to describe stifle syndrome diagnosis in horses. From 2001 through 2012, 810 athletic horses involved in different disciplines were examined using the technique of acupuncture diagnosis. Stifle syndrome was suspected when the following points were reactive: the sacral point suggestive of stifle disease located at the sacral origin of the biceps femoris muscle, bladder (BL)-20, BL-21, and stomach (ST)-30, together with the three local points in the muscle groove of the posterolateral aspect of the thigh. The diagnostic protocol included radiography and/or ultrasonography in certain cases. The horses were evaluated because of reduced athletic performance, routine or prepurchase examination, hind limb lameness, refusal to jump, inappetence, upward fixation of the patella, thoracolumbar spine or sacroiliac pain, suspensory lesion, and front hoof problems, and 86 (9.4%) were diagnosed with stifle syndrome. The sacral acupuncture point suggestive of stifle syndrome correlated with BL-21, local stifle points, gall bladder (GB)-27, spleen-13, BL-23, BL-52, BL-26, and/or GB-25, ST-30, BL-54 (P < .0001), and BL-20 (P = .003). Twenty-two (25.6%) of the 86 horses with stifle syndrome underwent ultrasonography and/or radiography, and lesions were detected in 21. In conclusion, acupuncture for diagnosis of stifle disease may be considered a diagnostic method to be included in routine clinical examination of horses, and its reproducibility shall be investigated in further studies.  相似文献