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1.
Genetic selection for carcass traits is paramount to maximize the profitability and long‐term sustainability of any meat‐producing livestock species. The main objectives of this research were to evaluate the efficiency of indicator traits for the genetic improvement of lamb carcass traits and to determine the value of including carcass traits into terminal sire selection indexes for the Canadian sheep industry. The carcass traits included hot carcass weight (HCW), fat depth at the GR site (FATGR) and average carcass conformation score (AVGCONF), and were measured on heavy lambs (slaughter age less than 365 days and HCW greater than 16.3 kg) in commercial abattoirs. Growth traits were found to be moderately efficient indicator traits for the genetic improvement of HCW but selection on ultrasound traits was necessary to substantially improve the carcass quality traits (FATGR and AVGCONF). Economic selection indexes were designed by adding various combinations of carcass traits into the Canadian Sheep Genetic Evaluation System terminal indexes. Records measured on individuals and progeny were assumed to be the sources of information for live animal and carcass traits, respectively. The changes in index accuracy, efficiency and expected correlated response were used to assess the value of their inclusion. HCW was found to have a large economic value, and its inclusion into terminal selection indexes was expected to substantially increase their accuracy (0.08–0.12 points) and efficiency (20%–30%). However, further including FATGR (measured 110 mm from the carcass midline over the 12th rib) and AVGCONF had little impact on the accuracy (≤0.03) and efficiency (1%–7%) of the proposed indexes. Thus, the inclusion of carcass traits into the existing terminal selection indexes could be beneficial for the genetic improvement of HCW, but further research is needed to determine optimal methods of increasing carcass fatness and muscularity.  相似文献   
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ObjectiveTo describe and evaluate an ultrasound-guided modified subcostal approach for the transversus abdominis plane (TAP) block in horse cadavers in lateral or dorsal recumbency.Study designProspective, experimental cadaveric study.AnimalsStudy of one preserved foal and eight fresh adult horse cadavers.MethodsThe lateral and ventral abdominal wall of a preserved cadaver was dissected to identify the muscles and nerves. A unilateral standard TAP block technique was performed (60 mL of methylene blue dye–bupivacaine) on a fresh cadaver in right lateral recumbency. A modified subcostal technique was performed on the opposite side using a linear ultrasound transducer and in-plane approach. Injection points (two 30 mL dye) were at the level of the TAP (between the rectus abdominis and transversus abdominis muscles and ventral to the cutaneous trunci muscle) perpendicular to: 1) the mid-point between the xiphoid cartilage and umbilical scar; and 2) at a point between the caudal and middle thirds of the abdomen measured from the first injection point to the umbilical scar. The modified subcostal approach was performed in seven additional cadavers in both hemiabdomens, with three cadavers in lateral and four cadavers in dorsal recumbency. Ultrasound guidance was used with all injections.ResultsThe standard approach stained the sixteenth to eighteenth thoracic nerves (T16–T18). The modified subcostal approach performed in lateral recumbency provided greater spread (T9–T17) than dorsal recumbency (T12–T18) (p = 0.016).Conclusions and clinical relevanceThe modified subcostal TAP approach resulted in extensive staining exceeding the standard approach. The nerves stained are consistent with production of ventral abdominal wall anesthesia in horses. Clinical studies are needed to verify these findings.  相似文献   
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When using saline waters, sprinkling irrigation at night is a recommended practice to reduce evaporation, salt absorption by the wetted leaves and its negative effects on crops. We measured shoot ion concentrations (Cl, Na+ and K+) and total dry matter (TDM) in alfalfa subject to diurnal and nocturnal saline sprinkler irrigations and established potential relationships among them. The work was carried out along the 2004–2006 growing seasons using EC waters from 0.5 to 5.6 dS m−1. Saline sprinkling irrigations linearly increased shoot Cl and Na+ and decreased shoot K+. Even though daytime evaporation was much higher than nigh-time, shoot ion accumulation and TDM were similar in the diurnal and nocturnal irrigations. The salinity tolerance of alfalfa decreased in year 2006 due to increases in shoot Cl and, particularly, shoot Na+. The lower threshold for shoot Na+ (276 meq kg−1) than for shoot Cl (726 meq kg−1) shows that alfalfa is more sensitive to Na+ than to Cl, and that Na+ accumulation is the preponderant cause of alfalfa yield decline after 3 years of sprinkling with saline waters.  相似文献   
5.
This study evaluated the effect of the density at harvest on the performance and profitability of hatchery‐reared spotted rose snapper cultured in cages. The fish were stocked at harvest densities of 15, 20, and 22 kg/m3 in cages of 222 and 286 m3. More than 39,000 snapper fingerlings with an initial weight of 14 g were stocked. The fish were fed an extruded diet and cultured over a 360 d period. The thermal growth coefficient ranged from 0.04 to 0.05 and survival was 95% for all treatments, with the highest final weight (436.8 g) observed for fish reared at a density of 20 kg/m3. The allometric value b indicated that hatchery‐raised, cage‐cultured snapper were heavier than their wild counterparts. The major costs were feed (ranging from 44.7–45.9%), labor (22.4–32.6%), and seed costs (20.2–26.1%). The total production cost ranged from US$ 6.5 to US$ 7.5/kg. The baseline scenario was not economically feasible. However, a 10% increase in the sales price resulted in increases in the internal rate of return (183%) and net present value (US$ 97,628.9). These results suggest that L. guttatus has the potential for commercial production in cages.  相似文献   
6.
OBJECTIVE: To determine whether plasma, urine, and fecal electrolyte and mineral concentrations differ between clinically normal horses and Thoroughbreds with recurrent exertional rhabdomyolysis (RER) after consumption of diets varying in cation-anion balance. ANIMALS: 5 Thoroughbred mares with RER and 6 clinically normal mixed-breed mares. PROCEDURE: Each of 3 isocaloric diets designated as low, medium, and high on the basis of dietary cation-anion balance (DCAB) values of 85, 190, and 380, respectively, were fed to horses for 14 days. During the last 72 hours, 3 horses with RER and 3 control horses had daily urine and fecal samples obtained by total 24-hour collection. Remaining horses had urine samples collected daily by single catheterization. RESULTS: For each diet, no differences existed between horses with RER and control horses in plasma pH, electrolyte concentrations, and creatine kinase activity or in urine pH and renal fractional excretion (FE) values. Plasma pH, strong ion difference, bicarbonate and total carbon dioxide concentrations, and base excess decreased and plasma chloride and ionized calcium concentrations increased with decreasing DCAB. Urine pH decreased with decreasing DCAB. The FE of chloride and phosphorus were greatest for horses fed the low diet. The FE values for all electrolytes exept magnesium did not differ between urine samples obtained by single catheterization and total 24-hour collection. Daily balance of calcium, phosphorus, sodium, chloride, and potassium did not differ significantly among horses fed the various diets. CONCLUSIONS: In clinically normal horses and in horses with RER, the DCAB strongly affects plasma and urine pH and the FE of sodium, potassium, chloride, and phosphorus.  相似文献   
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Interest in conversion of marginal agricultural lands to small oak woodlands for the production of black truffles (Tuber melanosporum Vittad.) is increasing in the native black truffle areas of France, Spain and Italy as well as suitable or amended sites throughout the world due to high economic returns for gastronomically valuable truffles. Successful long-term management of a perennial plantation replacing an annual crop requires understanding the system in all phases of the life cycle, and in the case of truffles this involves understanding the interactive growth of the aboveground host and the belowground symbiotic ectomycorrhizal fungus whose fruitbody is the desired truffle. Here we focus on the pre-production phase, 4 years after establishing the truffle-oak plantation and prior to truffle production. We tested the influence of weed control, irrigation and fertilizer, each at 3 levels, on plant growth and ectomycorrhizal proliferation in three truffle-oaks plantations in northeast Spain. Results show that adequate weed control improves root and shoot dry weight while fertilizer and irrigation treatments did not influence plant growth. The low dose of irrigation (50% of the estimated water deficit for the site) and glyphosate weed control both increased total root tips/plant and T. melanosporum colonized tips (ectomycorrhizae) by approximately two-fold, compared to control treatments. Distribution of the ectomycorrhizae within the soil profile was significantly influenced by the low dose irrigation treatment, with increases observed in the 10?C20 cm and the 20?C30 cm deep layers compared to the control and high irrigation treatments. Four years after planting, T. melanosporum remained the dominant fungal symbiont, despite the presence of 14 other ectomycorrhizal morphotypes from these sites.  相似文献   
9.
Sulfluramid is an expensive active principle of insecticidal baits that is lost by volatilization during the pelletization of baits. To increase the thermal stability of sulfluramid, we tested its molecular encapsulation in beta-cyclodextrin (beta-CD), using molar ratios of 1:1 and 1:2 (sulfluramid:beta-CD), using the complex preparation techniques of coprecipitation and kneading. The physical mixture of sulfluramid and beta-CD was also tested for comparison. The products of complexation were characterized by differential scanning calorimetry, thermogravimetry, and derivative thermogravimetry, indicating the formation of a sulfluramid/beta-CD complex and showing that the release of the complexed sulfluramid occurs in the range of 270-300 degrees C, a temperature range that is well above the temperature at which sulfluramid sublimates (40 degrees C). This result warrants a reduced sulfluramid loss in the preparation of insecticidal baits. The preparation of the complex by kneading with molar ratio of 1:2 gave the highest yield of complex, about 64%, in relation to the theoretical maximum.  相似文献   
10.
Enzymatic activity (EA) was explored as a possible tool for composting characterization. Three composts (yard wastes, cotton wastes and a mixture of the two) were sampled during different phases of the process and divided in two fractions. The first was immediately analysed for microbial biomass C (BC) and EAs (β-glucosidase, arylsulphatase, acid and alkaline phosphatase). The second fraction was air-dried prior to analysis for the same EAs and for organic C (CORG), total N (NTOT), dissolved organic C (DOC), extractable C (CE) and humic-like C (CH).BC decreased throughout the composting period (149 days), whereas EA in moist fractions stabilized between 50 (β-glucosidase, alkaline phosphatase) and 90 (arylsulphatase, acid phosphatase) days of composting.EA was always reduced by air‐drying (β-glucosidase: 40-80%; arylsulphatase: 10-50%; acid phosphatase: 10-70%; alkaline phosphatase: 50-90%), but this effect was less prominent as composting proceeded, especially for β-glucosidase and alkaline phosphatase.EA in air-dried samples displayed the same trend as in moist ones, except that there was a marked difference (47-66%) between initial and final activities of all four enzymes.EAs in air‐dried compost and content of humic-like substances showed a similar trend: a marked increase in the first 90 days of the process and no significant variations afterwards. This suggests that the formation of humic-enzymatic complexes has taken place and indicates that this process occurs almost totally during the first stage of composting.EA steadiness in air-dried samples occurred concurrently with the achievement of compost stability, as indicated by the conventional indexes (i.e. CH, CORG/NTOT). Therefore, the development of a stable enzyme activity in air-dried compost could represent a simple measure of compost stabilization in routine analysis of composting process.  相似文献   
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