Optimum geometric layout of a single cable road

Cable-based technologies have been a backbone for harvesting on steep slopes. The layout of a single cable road is challenging because one must identify intermediate support locations and heights that guarantee structural safety and operational efficiency while minimizing set-up and dismantling costs. Our study objectives were to (1) develop an optimization approach for designing the best possible intermediate support layout for a given ground profile, (2) compare optimization procedures between linearized and nonlinear analyses of a cable structure and (3) investigate the effect of simplifying a multi-span representation. Our results demonstrate that the computational effort is 30–60 times greater for an optimization approach based on nonlinear cable mechanical assumptions than when considering linear assumptions. Those nonlinear assumptions also stipulate lower heights for intermediate supports and a larger span length. Finally, compared with the unloaded case, tensile force in the skyline is increased by as much as 80% under load for a single-span skyline configuration. Our approach provides additional value for cable operations because it ensures greater structural safety at a lower cost for installation. Improvements are still needed in developing a stand-alone application that can be easily distributed. Moreover, our rather simple assumptions regarding set-up and dismantling costs must be refined.     

The incidence of agglutination and its influence on sperm quality and fertility of boar semen

The aim of this study was to examine the incidence of sperm agglutinations and their relationships with sperm quality and fertility. Semen samples of 40 boars of an AI-station were investigated. Nineteen of the 40 investigated boars showed a constantly low (< 10% agglutinated sperm), 3 an intermediate (10-20%) and 6 boars a high level (> 20%) of agglutination in raw semen. The degree of agglutination in sperm samples of 12 boars varied distinctly during the investigation period. During summer more (P < 0.05) agglutinated sperm were observed (11.0 +/- 11.6%) than during winter (6.2 +/- 7.3%). There was no association between bacterial contamination and incidence of agglutinations (P > 0.05). After dilution in extender the percentage of agglutinated sperm decreased from 6.2 +/- 7.3% to 1.1 +/- 1.4% (P < 0.0001). Twenty-four hours after dilution the percentage of progressively motile sperm was 7.4% lower (P < 0.05) in ejaculates with an initially high degree of agglutination (> 20% agglutinated sperm) compared to samples with an initially low degree of agglutinated sperm (< 10%). Plasma membrane integrity, mitochondrial membrane potential, acrosome reaction and chromatin structure were independent (P > 0.05) from the level of agglutination. Fertility data did not differ (P > 0.05) between boars with low and high numbers of agglutinated sperm in raw semen. The results show that there are individual, ejaculatory and seasonal variations in the incidence and degree of agglutination. Agglutinations have a negative effect on motility of sperm and disappear to a large extent after dilution in sperm extender. They have no negative consequences on fertility.     

The clinical diagnosis of BSE

Diagnosis of Bovine spongiform encephalopathy (BSE) is confirmed by specified laboratory methods on brain material. On the other hand clinical signs of manifest BSE are quite obvious. The first part of this paper describes case histories, clinical signs, laboratory findings and the most common differential diagnoses. On the basis of the data of actual prevalence in Germany, the role of clinical examination in eradication of BSE is dealt in the second part. Clinical diagnosis is a very sensitive and specific method when there is a high prevalence. According to the data from December 2000 to November 2001 prevalence in Germany was beyond 1 BSE case per 100,000 cattle or 3 cases per 100,000 cows. This very low prevalence decreases rapidly sensitivity and specificity of the diagnosis made by clinical examination. Therefore the main focus of field-diagnostics has to be laid on specified laboratory diagnostic methods. On the other hand prevalence of BSE-positive cattle is distinctly higher in the group of animals slaughtered in cases of illness or emergency than in cattle slaughtered on the regulatory bases. Nevertheless every veterinary practitioner should be aware of the clinical picture of BSE, clinical examination-routine and differential diagnosis, because occurrence of BSE is still possible in any dairy herd. At the moment it is not possible to make any statement if eradication of BSE can be reached in future.     

Using “Uterine Index” to diagnose embryonic death in mares

Embryonic death plays an important role in infertility in mares, and most of embryonic mortality occurs at an early stage (before day 40) of pregnancy. Previous investigations focused on B-mode sonographic images to determine abnormal pregnancy; however, no study has provided a quantitative and objective method to diagnose embryonic death. Here we developed a new index, “Uterine Index,” using color Doppler sonography to describe alterations of uterine blood flow in physiological and pathological gestations during early gestation. Six Trotter mares were used in this study. The pregnancies were interrupted with a prostaglandin F2α (PGF_2α) analog (tiaprost) at days 25, 30, and 40. Three gestations were investigated in each stage. After the PGF_2α administration, these mares were examined every 8 hours until the embryonic vesicles were not visible on ultrasound. In the control group, three pregnancies were examined daily from days 12 to 60. The embryo size was measured in B-mode sonography, and the blood flow in uterine arteries was examined in Doppler ultrasound. The resistance index (RI) and uterine index (UI) were calculated. In the control group, the RI values of uterine artery were lower in pregnant side compared with that of the non-pregnant side from day 15 on, and the difference became greater as the pregnancy advanced (P < .05). The UI was close to 0 before week 3 and increased to approximately 10 after week 4. In the PGF_2α-treated group, the UI values reduced from pregnancy level to approximately 0. As early as 32 hours before embryonic death, we observed a significant difference of UI values between control and treated mares. On the contrary, the embryo size of treated mares was not different from that of normal mares. Through the analysis of all recorded UI values, we suggest that the UI values 10 and 5 are good values for distinguishing normal pregnancy (UI >10) from embryonic death (UI < 5). If the UI values are located between 10 and 5, a reexamination at intervals of 1 to 3 days is recommended. Our findings demonstrate that the UI is a useful method to diagnose and predict embryonic death in mares by providing reliable and objective information.     

Impact of a simultaneous application of anionic salts and rumen buffer on acid-base-balance and mineral metabolism in dairy cows

In this study, the influence of simultaneous application of anionic salts (AS) and rumen buffer (RB) on the metabolism of dairy cows was examined. Eleven rumen fistulated, non-pregnant and non-lactating dairy cows received equal amounts of one AS (CaCl2 or CaSO4) and one RB (NaHCO3 or KHCO3) via rumen cannula during feeding time over a period of eight days. Before the first application of AS and RB and on day eight of the treatment period, blood, urine and rumen fluid samples were taken. The following parameters were measured: whole blood: pH, base excess, bicarbonate; serum: sodium, potassium, chloride, calcium; urine: pH, net acid base excretion, sodium, potassium, chloride, calcium; rumen fluid: pH. The changes of each parameter were compared via ANOVA.The changes in acid-base balance on day eight were very small, although significant. But p-values showed that the statistical evidence was low.The most changes occurred when NaHCO3 was fed in combination with one of the AS used. In this case a small acidogenic load was seen in blood (p < 0.05), and calcium concentrations increased slightly (p < 0.05). No alkalotic reaction could be detected when any combination of AS and RB were given to the cows. Simultaneous application of AS and RB results in a loss of effectivity of AS. Neither an adequate acidification of blood nor an activation of calcium metabolism occurred. In feed ration for cows in the last weeks of pregnancy, rumen buffer must not be fed, if anionic salts are given for prevention of parturient paresis.