Evaluation of biological and economic efficiency of the All Heifer,No Cow beef production system using a system dynamics model based on 6 yr of demonstration herd data     

Meredith A Harrison  John J Sheehan  George E Seidel  Jr.  Dan F Mooney  Ryan D Rhoades  Jason K Ahola 《Journal of animal science》2021,99(1)

Alternative management strategies with no cows and all heifers may improve biological and economic efficiency of beef production. The All Heifer, No Cow (AHNC) beef production system involves insemination of nulliparous heifers with female sex-selected semen (FSS) to produce primarily female calves that are early weaned at 3 mo of age. Dams are finished on a high concentrate diet and harvested before 30 mo of age. The objectives of this research were to: 1) build a dynamic model of an AHNC beef production system to quantify system biological and economic efficiency; 2) compare effects of utilizing FSS vs. conventional semen on biological and economic efficiency; 3) evaluate what-if scenarios to determine the effects on biological and economic efficiency of changing variables ±5%, 10%, 15%, and 20% from initial observed values; and 4) evaluate the effects on biological and economic efficiency of changing variables ±10% from initial observed values. A model was built over a 21-yr horizon using Stella Architect. Biological parameter values in the model were based on the 6 yr of data collected from the management of an AHNC demonstration herd. In the model animal, total digestible nutrients (TDN) intake, hot carcass weight (HCW), and age at harvest were randomized. Feed, animal, and carcass prices included in the model were based on 10 yr of historical U.S. price data. Key response variables were biological and economic efficiency (mean ± SD). Biological efficiency was defined as the ratio of output (kilograms of HCW produced) to input (lifetime kilograms of feed TDN consumed), and economic efficiency was measured using a benefit–cost ratio (BCR) and unit variable cost (UVC). Over 40 simulation runs, the predicted mean biological efficiency was 0.0714 ± 0.0008. Economic efficiency was 0.95 ± 0.02 and US $445.41 ± 0.06 for BCR and UVC, respectively. Biological and economic efficiency was improved in the conventional semen scenario; biological efficiency was 0.0738 ± 0.0008, and BCR and UVC were 0.99 ± 0.04 and US $407.24 ± 0.006, respectively. Under this parameterization and market conditions, the AHNC beef production system failed to achieve profitability under any scenario that was evaluated. However, this review did not account for the potential increased genetic benefit from a decreased generation interval and the reduction in feed energy in comparison to a conventional cow/calf system.  相似文献   

Canine calvarial subperiosteal hematomas are fluid to soft tissue attenuating mass‐like lesions with smoothly marginated peripheral mineralization on CT     

Ava Nowak  Ryan King  Agustina Anson 《Veterinary radiology & ultrasound》2021,62(1):44-53

Subperiosteal hematomas are accumulations of blood between a bone and the periosteum leading to elevation of the periosteum. When ossified they have a mineralized outer rim. For this retrospective, multi‐institutional case series, medical records were searched to identify dogs that underwent CT for focal calvarial swellings noted acutely after trauma. A total of four dogs were included. Computed tomography images were reviewed for each case. The focal swellings had progressed in size during the weeks after the head trauma until the time of imaging. Findings in all cases included a fluid to soft tissue attenuating mass‐like lesion with smoothly marginated peripheral mineralization. Diagnosis was confirmed in two cases by cytology and/or histopathology. Therefore, authors recommend that subperiosteal hematoma be included in the differential diagnosis list for dogs with these clinical and CT characteristics. Based on our review of the literature, this is the first report to describe the CT features of calvarial subperiosteal hematomas in dogs.  相似文献   

Treatment of indolent cutaneous T-cell lymphoma with hypofractionated radiation therapy in three cats     

Laura E. Chadsey  Matthew R. Cook  Eric E. Green  Ryan N. Jennings  Peter F. Moore  William Vernau  William C. Kisseberth  Sandra F. Diaz 《Veterinary dermatology》2021,32(5):515-e143

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Fluoroquinolone exposure in utero did not affect articular cartilage of resulting foals     

Robyn E. Ellerbrock  Igor F. Canisso  Ryan J. Larsen  Katherine S. Garrett  Matthew C. Stewart  Kalyn K. Herzog  Mariana E. Kersh  Sara G. Moshage  Giorgia Podico  Fabio S. Lima  Bronwen A. Childs 《Equine veterinary journal》2021,53(2):385-396

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Is low-level laser therapy useful as an adjunctive treatment for canine acral lick dermatitis? A randomized,double-blinded,sham-controlled study     

Amy H. Schnedeker  Lynette K. Cole  Sandra F. Diaz  Gwendolen Lorch  Päivi J. Rajala-Shultz  Ryan N. Jennings  Eric T. Hostnik  Joshua B. Daniels 《Veterinary dermatology》2021,32(2):148-e35

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Bioactivity of Backhousia citriodora: antibacterial and antifungal activity   总被引：2，自引：0，他引：2  

Wilkinson JM  Hipwell M  Ryan T  Cavanagh HM 《Journal of agricultural and food chemistry》2003,51(1):76-81

Backhousia citriodora products are used as bushfoods and flavorings and by the aromatherapy industry. The antimicrobial activity of 4 samples of B. citriodora oil, leaf paste, commercial tea (0.2 and 0.02 g/mL), and hydrosol (aqueous distillate) were tested against 13 bacteria and 8 fungi. Little or no activity was found to be associated with the leaf tea and hydrosol, respectively. Leaf paste displayed antimicrobial activity against 7 bacteria including Clostridium perfringens, Pseudomonas aeruginosa, and a hospital isolate of methicillin resistant Staphylococcus aureus (MRSA). The 4 essential oils were found to be effective antibacterial and antifungal agents; however, variation was apparent between oils that did not correlate with citral content. The antimicrobial activity of B. citriodoraessential oils was found to be greater than that of citral alone and often superior to Melaleuca alternifolia essential oil. B. citriodora has significant antimicrobial activity that has potential as an antiseptic or surface disinfectant or for inclusion in foods as a natural antimicrobial agent.  相似文献   

Topographic and biotic regulation of aboveground carbon storage in subtropical broad-leaved forests of Taiwan   总被引：2，自引：0，他引：2  

Ryan W. McEwanYi-Ching Lin  I-Fang SunChang-Fu Hsieh  Sheng-Hsin SuLi-Wan Chang  Guo-Zhang Michael SongHsiang-Hua Wang  Jeen-Lian HwongKuo-Chuan Lin  Kuoh-Cheng YangJyh-Min Chiang 《Forest Ecology and Management》2011,262(9):1817-1825

There is a growing need to understand, and ultimately manage, carbon storage by forest ecosystems. Broad-leaved evergreen forests of Taiwan provide an outstanding opportunity to examine factors that regulate ecosystem carbon storage. We utilized data from three Taiwan Forest Dynamics Plots (FS, LHC, and PTY) in which every tree is identified, measured, tagged and mapped, to examine factors regulating carbon storage as estimated from aboveground biomass. Allometric equations were used to estimate the aboveground biomass of each tree, and a model building procedure was used to examine relationships between plot-level aboveground biomass (AGB; Mg/ha) and a suite of topographic and biotic factors. We found that our study sites have AGB values comparable to some of the most carbon dense forests in the world. Across all three sites, maximum biomass was contained in the taxonomic families Fagaceae, Lauraceae and Theaceae. In the FS site, we identified slope convexity (P = 0.03) and elevation (P < 0.001) as topographic predictors of AGB and found that maximum AGB was found in topographically flat areas. In FS, stem density (P < 0.001) was a significant biotic predictor of AGB and the maxima occurred at intermediate densities. In LHC, we found that convexity (P < 0.001) and slope (P < 0.001) were significantly related to AGB which was maximized along a topographic ridge in the plot. Species richness (P < 0.001) was a significant biotic predictor of AGB in LHC, and the relationship indicated slightly higher AGB at higher levels of species richness. The only significant factor related to AGB in PTY was species richness (P = 0.02). Further work is needed to seek a mechanistic understanding of topographic factors and species richness as drivers of carbon storage in forests.  相似文献   

A single recessive gene conferring short leaves in romaine × Latin type lettuce (Lactuca sativa L.) crosses,and its effect on plant morphology and resistance to lettuce drop caused by Sclerotinia minor Jagger     

Ryan J. Hayes  BoMing Wu  Krishna V. Subbarao 《Plant Breeding》2011,130(3):388-393

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Canopy and hydraulic conductance in young, mature and old Douglas-fir trees   总被引：1，自引：0，他引：1  

Phillips N  Bond BJ  McDowell NG  Ryan MG 《Tree physiology》2002,22(2-3):205-211

We tested for reductions in water transport with increasing tree size, a key component in determining whether gas exchange and growth are hydraulically limited in tall trees. During the summers of 1998 and 1999, we measured water transport with Granier-type, constant-heat sap flow probes, vapor pressure deficit, and leaf and soil water potentials in overstory Pseudotsuga menziesii (Mirb.) Franco trees in three stands differing in size and age (15, 32 and 60 m in height and about 20, 40 and 450 years in age, respectively) in a P. menziesii-dominated forest in the Pacific Northwest, USA. A total of 24 trees were equipped with sap flow sensors--six 60-m trees, nine 32-m trees and nine 15-m trees. Based on the sap flow measurements and leaf area information estimated from leaf area-sapwood area relationships, we estimated crown-averaged stomatal conductance (GS) and leaf-specific hydraulic conductance (KL). We tested the hypothesis that GS and KL vary inversely with tree height (15 > 32 > 60 m). Analysis of variance of GS ranked as 15 = 60 > 32 m during the early summer and 15 > 60 > 32 m during late season drought. Over the growing season, mean daily GS (+/- SE) was 29.2 +/- 4.4, 24.0 +/- 6.8 and 17.7 +/- 7.2 mmol m-2 s-1 for the 15-, 60- and 32-m trees, respectively. The value of K(L) differed among tree heights only during late season drought and ranked 15 > 32 = 60 m. A hydraulic mass balance suggests that greater sapwood conductivity in 60-m trees compared with 32- and 15-m trees is a likely cause for the departure of the above rankings from those predicted by height and leaf-to-sapwood area ratio.  相似文献   

The PP2A-associated protein alpha4 is an essential inhibitor of apoptosis     

Kong M  Fox CJ  Mu J  Solt L  Xu A  Cinalli RM  Birnbaum MJ  Lindsten T  Thompson CB 《Science (New York, N.Y.)》2004,306(5696):695-698

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