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921.
P.G. Gibbs PhD G.D. Potter PhD G.T. Schelling PhD J.L. Kreider PhD C.L. Boyd DVM 《Journal of Equine Veterinary Science》1996,16(2):60-65
Mature ponies fitted with permanent ileal cannulas were used in two 3×3 Latin square experiments to quantify prececal, postileal and total tract digestion of N. In trial 1, corn, oats and sorghum were each fed with coastal Bermuda grass hay in 75:25 ratios. Apparent prececal digestibilities were similar (P>.05) and averaged 46.6%. By-difference procedures were employed to calculate digestibility of the cereal grain N only and apparent prececal N digestibility averaged 57.1%. In trial 2, a basal corn and hay diet was supplemented with cottonseed meal and soybean meal. Apparent total tract N digestibilities were similar (P>.05) across treatments, and prececal digestibility averaged 45.6%. By-difference calculations were used to determine digestibility of SBM and CSM N alone. Apparent prececal digestibility of SBM was 52.5% and was lower (P<.05) than 81.2% for CSM. It is possible that inadequate or excessive heat treatment of SBM affected enzymatic digestion. True digestibility of total rations fed in trial 2 was estimated by linear regression of nitrogen digested on nitrogen intake or N presented to the large intestine. True N digestibility of diets containing SBM and CSM was 54.7% and 69.4%, respectively. 相似文献
922.
Portfolio theory, an established technique in the selection of stocks and financial instruments for investment purposes, was used as a means of selecting an economic mix of veterinary interventions in a dairy herd. The expected return on investment in six veterinary services and the associated standard deviations (as measures of risk) were calculated using computer simulation modeling techniques. Mathematical programming techniques were applied to identify the optimal combinations of veterinary interventions which maximize expected financial returns while minimizing risk. Parametric analysis was used to show how risk (standard deviation) increases as the required expected return is increased along the efficient risk-return frontier of these optimal combinations. This exercise emphasizes the importance of regarding risk in addition to expected return when considering investment in veterinary services. 相似文献
923.
Concentrations of bioactive and immunoactive luteinizing hormone in bovine anterior pituitary tissue
G E Moss R P Lemenager J R Parfet B M Adams T E Adams 《Domestic animal endocrinology》1988,5(2):185-190
Tissue concentrations of LH as determined by radioimmunoassay (RIA) may not accurately measure actual changes that could occur in biological activity of the hormone. To examine this possibility, pituitary homogenates from 135 beef cows in various physiological states were analyzed for content of LH by both RIA and an in vitro bioassay. The ratio of biological/immunological active concentrations of LH remained constant (.52 +/- .02) even though tissue concentrations of immunoactive LH differed among groups. Tissue concentrations of bioactive LH were linearly related to, and highly correlated with (P less than .001), tissue concentrations of immunoactive LH. These data indicate that only a fraction of the immunoactive LH in the bovine pituitary is biologically active. However, this fraction does not vary with the reproductive status or plane of nutrition. 相似文献
924.
Interaction of sub-epithelial connective tissue components with Staphylococcus aureus and coagulase-negative staphylococci from bovine mastitis 总被引:4,自引:0,他引:4
Staphylococcus aureus and coagulase-negative staphylococci (CNS) isolated from bovine mastitis were examined for their ability to interact with 125I-labelled fibronectin, fibrinogen and type II collagen. Their relative surface hydrophobicity and production of extracellular capsule were also investigated. Almost all S. aureus strains bound fibronectin (mean value 23%), fibrinogen (mean value 12%) and type II collagen (mean value 16%). CNS bound fibronectin (mean value 6%) and type II collagen (mean value 7%), but not fibrinogen (mean value 2%). The specificity of binding of these proteins to S. aureus strain F1440 and to coagulase-negative Staphylococcus chromogenes strain BO52 was studied by adding an excess of unlabelled proteins. Fibronectin and collagen binding were observed to be specific, varying between 50 and 75%, whereas the specificity of fibrinogen binding to S. aureus strain F1440 was lower (26%). Most of the S. aureus strains (63%) showed very high surface hydrophobicity (autoaggregation) or lower hydrophobicity (29% of the strains) and the rest were hydrophilic. None of the CNS strains autoaggregated, 44% were classified as hydrophilic strains. Hydrophilic strains (except the reference strains) did not show extracellular capsule production. However, the encapsulated (reference) strains showed low binding to these proteins as compared to their unencapsulated variants. Pre-treatment of S. aureus strain F1440 and S. chromogenes strain BO52 with trypsin decreased their fibronectin binding capacity and surface hydrophobicity, whereas pre-treatment with bovine milk (except on collagen binding to strain F1440) did not significantly affect binding to these proteins. These data indicate that S. aureus and CNS isolated from bovine udder infection have the ability to bind to tissue matrix and plasma proteins which may be exposed in the traumatized or toxin-damaged udder epithelial lesions. 相似文献
925.
The effects of age, environmental temperature and relative humidity on the bacterial flora of the nose and trachea of calves were investigated by sequential sampling of three groups each of eight Friesian-Holstein male calves kept in three different environmental conditions. All calves were vaccinated with a live attenuated vaccine against infectious bovine rhinotracheitis (IBR) when they were 12 weeks old. Nasal and tracheal swabs were collected at 14-day intervals for bacteriological examinations. The upper respiratory tract of calves started to be colonized by various species of bacteria within the first day of life. Although they were born at different periods of the year, the calves in all three groups had similar bacterial loads in their noses and tracheas when they were 1 day old (P greater than 0.05). The total bacterial colony forming units (BCFU) were highly variable from calf to calf and from one time of sampling to another. Despite these variations, there were age-related increases in the total BCFU in nasal and tracheal swabs in all experiments. These increases were influenced by environmental temperature. Vaccination of the calves with a live IBR vaccine appeared to enhance the bacterial colonization of the upper respiratory tract. 相似文献
926.
A geometrical model of weft knitted spacer structures made with mono-filament yarn has been analysed to understand the spacer
yarn path. Theoretical models have been created to predict the porosity and the radius of the capillaries of a knitted spacer
structure depending on their geometrical parameters, such as course spacing, wale spacing, stitch length, fabric thickness,
count of yarn and fibre density. Polyester knitted spacer fabrics were produced with different parameters; their porosity
was determined by measuring the weight and compared with the theoretical porosity. The validity of the model was confirmed
by experimental results. The porosity of knitted spacer structures made out of mono-filament yarn can be maintained above
a certain level by adjusting the fabric parameters such as fabric thickness, course spacing and wale spacing. 相似文献
927.
本实验分析了9个红麻品种在南非地区的产量稳定性.结果显示,在南非纳塔尔地区,红麻产量的基因型和环境相互作用显著.在不同的参试地区和年份中,红麻鲜重,鲜茎产量以及干茎产量均为极显著差异.灌溉条件下各产量指标明显高于干旱地区.本实验还应用了3个不同的参数和方案,评估了这9个品种的稳定性.结果表明,综合三个参数,EI Salvador是在不同环境条件下具有丰产潜力的品种. 相似文献
928.
Reduction of runoff and soil loss over steep slopes by using vetiver hedgerow systems 总被引:2,自引:0,他引:2
Vetiver hedgerow system has potential for reducing runoff and soil loss especially on steep slope areas, but the dynamics of these reductions are not fully understood. This research was conducted to determine reduction in runoff and soil loss by vetiver hedgerow system. Vetiver hedgerow systems with three vertical intervals of hedgerow were tested on three land slopes and compared with the case without hedgerow for six simulated rainfall amounts. The vetiver hedgerows reduce runoff volume and soil loss by 31–69 and 62–86 %, respectively compared to the case without vetiver hedgerow. Runoff volume increases with rainfall amount, and hence increases soil loss. Therefore soil loss increases with land slope, runoff volume, rainfall amount, and vertical hedge interval. Two final equations for estimating soil loss are presented in this study. The first equation contains parameters of runoff volume, land slope, and vertical hedge interval, while the second equation contains rainfall amount instead of runoff volume. The correlation coefficients between estimated soil losses and the experimental data in this study and in the literatures were found to be 0.94 and 0.90 for the first and second equations, respectively. 相似文献
929.
T K Herath H W Ferguson K D Thompson A Adams R H Richards 《Journal of fish diseases》2012,35(11):799-808
Studies on the ultrastructural morphogenesis of viruses give an insight into how the host cell mechanisms are utilized for new virion synthesis. A time course examining salmonid alphavirus 1 (SAV 1) assembly was performed by culturing the virus on Chinook salmon embryo cells (CHSE‐214). Different stages of viral replication were observed under electron microscopy. Virus‐like particles were observed inside membrane‐bound vesicles as early as 1 h following contact of the virus with the cells. Membrane‐dependent replication complexes were observed in the cytoplasm of the cells, with spherules found at the periphery of late endosome‐like vacuoles. The use of intracellular membranes for RNA replication is similar to other positive‐sense single‐stranded RNA (+ssRNA) viruses. The number of Golgi apparatus and associated vacuoles characterized by ‘fuzzy’‐coated membranes was greater in virus‐infected cells. The mature enveloped virions started to bud out from the cells at approximately 24 h post‐infection. These observations suggest that the pathway used by SAV 1 for the generation of new virus particles in vitro is comparable to viral replication observed with mammalian alphaviruses but with some interesting differences. 相似文献
930.
Shinichiro Ogawa Makoto Kimata Masamitsu Tomiyama Masahiro Satoh 《Journal of animal science》2022,100(3)
We estimated heritabilities of semen production traits and their genetic correlations with litter traits and pork production traits in purebred Duroc pigs. Semen production traits were semen volume, sperm concentration, proportion of morphologically normal sperms, total number of sperm, and total number of morphologically normal sperm. Litter traits at farrowing were total number born, number born alive, number stillborn, total litter weight at birth, mean litter weight at birth, and piglet survival rate at birth. Litter traits at weaning were litter size at weaning, total litter weight at weaning, mean litter weight at weaning, and piglet survival rate from birth to weaning. Pork production traits were average daily gain, backfat thickness, and loin muscle area. We analyzed 45,913 semen collection records of 896 boars, 6,950 farrowing performance records of 1,400 sows, 2,237 weaning performance records of 586 sows, and individual growth performance records of 9,550 animals measured at approximately 5 mo of age. Heritabilities were estimated using a single-trait animal model. Genetic correlations were estimated using a 2-trait animal model. Estimated heritabilities of semen production traits ranged from 0.20 for sperm concentration to 0.29 for semen volume and were equal to or higher than those of litter traits, ranging from 0.06 for number stillborn and piglet survival rate at birth to 0.25 for mean litter weight at birth, but lower than those of pork production traits, ranging from 0.50 for average daily gain to 0.63 for backfat thickness. In many cases, the absolute values of estimated genetic correlations between semen production traits and other traits were smaller than 0.3. These estimated genetic parameters provide useful information for establishing a comprehensive pig breeding scheme. 相似文献