A survey of the causes of mortality in adult mink, with emphasis on the lactation period

A study of the pattern and relative frequency of diseases in adult female mink during the lactation period was undertaken. All adult females that died between parturition (April/May) and July 1, 1990, from 48 farms in southern Ontario were selected for study, and the cause of death was determined by gross necropsy. In addition, the cause of death was determined by gross necropsy for all adults and weaned kits that died on one farm between April 1988 and March 1989.

The mortality rate among farms in the 1990 study, for adult females during the lactation period, ranged from 0.2% to 10.1%, with a median of 1.9%. Nursing disease (56%) was the most common diagnosis, followed by mastitis (11%), metritis (8%), and dystocia (7%). Escherichia coli and Staphylococcus spp. were the most frequent isolates from the cases of mastitis. In the 1988/1989 study, the mortality rate was highest from May to July, with a large increase in June as a result of nursing disease.

     

Time-frequency and complexity analyses for differentiation of physiologic murmurs from heart murmurs caused by aortic stenosis in Boxers

OBJECTIVE: To investigate whether time-frequency and complexity analyses of heart murmurs can be used to differentiate physiologic murmurs from murmurs caused by aortic stenosis (AS) in Boxers. ANIMALS: 27 Boxers with murmurs. PROCEDURES: Dogs were evaluated via auscultation and echocardiography. Analyses of time-frequency properties (TFPs; ie, maximal murmur frequency and duration of murmur frequency > 200 Hz) and correlation dimension (T(2)) of murmurs were performed on phonocardiographic sound data. Time-frequency property and T(2) analyses of low-intensity murmurs in 16 dogs without AS were performed at 7 weeks and 12 months of age. Additionally, TFP and T(2) analyses were performed on data obtained from 11 adult AS-affected dogs with murmurs. RESULTS: In dogs with low-intensity murmurs, TFP or T(2) values at 7 weeks and 12 months did not differ significantly. For differentiation of physiologic murmurs from murmurs caused by mild AS, duration of murmur frequency > 200 Hz was useful and the combination assessment of duration of frequency > 200 Hz and T(2) of the murmur had a sensitivity of 94% and a specificity of 82%. Maximal murmur frequency did not differentiate dogs with AS from those without AS. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that assessment of the duration of murmur frequency > 200 Hz can be used to distinguish physiologic heart murmurs from murmurs caused by mild AS in Boxers. Combination of this analysis with T(2) analysis may be a useful complementary method for diagnostic assessment of cardiovascular function in dogs.     

Effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group-housed sows

A total of 208 sows and 288 gilts (PIC line C29) were used to determine the influence of feeding frequency (2 vs. 6 times/d, floor fed) on performance and welfare measurements on a commercial sow farm. Treatments consisted of feeding similar amounts of feed to each sow (2.5 kg) or gilt (2.05 kg) over 2 (0700 and 1530) or 6 times daily (0700, 0730, 0800, 1530, 1600, and 1630). There were 8 sows or 12 gilts in each pen. Gilts and sows were moved to pens 1 to 4 d after breeding. In sows, there were no differences (P > 0.10) in ADG, backfat change, or variation in BW. There was a trend (P < 0.08) for sows fed twice daily to farrow more total pigs born, but number born alive or other reproductive performance traits were not different (P > 0.10) among treatments. Sows fed 6 times per day had increased vocalization during the morning (P < 0.07) and afternoon (P < 0.01) feeding periods compared with sows fed twice daily. Sows fed twice daily had more skin (P < 0.01) and vulva (P < 0.04) lesions as well as a small increase in feet and leg (P < 0.01) and hoof (P < 0.02) problems. In this commercial facility, the standard management protocol required moving gilts to a different gestation facility on d 42. On d 42, two pens of gilts with similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. Gilts fed 6 times daily had a tendency for greater ADG (P < 0.07) from d 0 to 42 and a tendency for greater (P < 0.09) backfat on d 42. After movement to the larger groups from d 42 to farrowing, ADG was similar (P > 0.10) for gilts fed 2 or 6 times daily. Gilts fed twice daily had lower BW variation at d 42 (P < 0.04) and tended to at farrowing (P < 0.10). In gilts, there were no differences (P > 0.10) for reproductive performance, skin and vulva lesions, and feet and leg scores. In conclusion, there were few growth, farrowing, or aggression differences among gilts fed 2 or 6 times daily. This suggests that either feeding method is suitable for group-housed gilts. Among sows, feeding frequency resulted in few growth or farrowing performance differences. Feeding 6 times daily resulted in a small but significant reduction in skin and vulva lesions and structural problem scores while increasing vocalization. Increasing the feeding frequency from 2 to 6 times daily does not appear to have a negative or positive impact on performance or welfare of group-housed gilts and sows.     

Transthoracic echocardiographic measurement of patent ductus arteriosus in dogs

BACKGROUND: Patent ductus arteriosus (PDA) size and morphology influence the selection of the kind and the size of the embolization device used to effect shunt closure. HYPOTHESIS: That echocardiographic measurement of PDA in dogs is accurate. ANIMALS: Forty-five client-owned dogs with PDA. METHODS: Prospective observational study. Echocardiographic and angiographic data were compared. RESULTS: Measurement of the ductus in color Doppler echocardiography (CD-E) and 2-dimensional echocardiography (2D-E) was achieved from left parasternal views in 43 of 45 unsedated dogs (96%). In these 43 dogs, the angiographic minimal PDA diameter was 3.72 +/- 1.59 mm, and the diameter of the PDA ampulla was 8.46 +/- 3.01 mm. The CD-E minimal PDA diameter ranged from 2.3 to 9.5 mm (median, 4.0 mm). There was a significant mean difference to the angiographic measurements (1.15 +/- 0.95 mm; P < .0001). An agreement in a 1-mm range was found in 21 of 43 dogs (48%). The 2D-E minimal PDA diameter was 3.73 +/- 1.78 mm, and the mean difference to the angiographic measurements was not significant (0.00 +/- 0.72 mm; P = .98). An agreement in a 1-mm range was found in 31 of 43 dogs (72%). The 2D-E measurement of the PDA ampulla revealed a significant mean difference to the angiographic data (1.95 +/- 2.43 mm, P < .0001). An agreement in a 2-mm range was found in 21 of 43 dogs (49%). CONCLUSIONS AND CLINICAL IMPORTANCE: The 2D-E from the left cranial parasternal view is an excellent noninvasive method to estimate the PDA minimal diameter before doing catheter intervention.     

Role of transpiration suppression by evaporation of intercepted water in improving irrigation efficiency

Sprinkler irrigation efficiency declines when applied water intercepted by the crop foliage, or gross interception (I_gross), as well as airborne droplets and ponded water at the soil surface evaporate before use by the crop. However, evaporation of applied water can also supply some of the atmospheric demands usually met by plant transpiration. Any suppression of crop transpiration from the irrigated area as compared to a non-irrigated area can be subtracted from I_gross irrigation application losses for a reduced, or net, interception (I_net) loss. This study was conducted to determine the extent in which transpiration suppression due to microclimatic modification resulting from evaporation of plant-intercepted water and/or of applied water can reduce total sprinkler irrigation application losses of impact sprinkler and low energy precision application (LEPA) irrigation systems. Fully irrigated corn (Zea Mays L.) was grown on 0.75 m wide east-west rows in 1990 at Bushland, TX in two contiguous 5-ha fields, each containing a weighing lysimeter and micrometeorological instrumentation. Transpiration (Tr) was measured using heat balance sap flow gauges. During and following an impact sprinkler irrigation, within-canopy vapor pressure deficit and canopy temperature declined sharply due to canopyintercepted water and microclimatic modification from evaporation. For an average day time impact irrigation application of 21 mm, estimated average I_gross loss was 10.7%, but the resulting suppression of measured Tr by 50% or more during the irrigation reduced I_gross loss by 3.9%. On days of high solar radiation, continued transpiration suppression following the irrigation reduced I_gross loss an additional 1.2%. Further 4–6% reductions in I_gross losses were predicted when aerodynamic and canopy resistances were considered. Irrigation water applied only at the soil surface by LEPA irrigation had little effect on the microclimate within the canopy and consequently on Tr or ET, or irrigation application efficiency.     

Antibody response to Raboral VR-G® oral rabies vaccine in captive and free-ranging black-backed jackals (Canis mesomelas)

Rabies is a zoonotic disease that remains endemic in large parts of southern Africa because of its persistence in wildlife and domestic dog vectors. The black-backed jackals (Canis mesomelas) is primarily the wildlife vector responsible for rabies outbreaks in northern parts of South Africa. Two trials were carried out to investigate antibody responses to the oral rabies vaccine Raboral V-RG® in black-backed jackals under captive and free-ranging conditions. In captive jackals 10/12 (83%; 95% confidence interval [CI]: 52% – 98%), seroconverted after single oral vaccination. Nine captive jackals had protective antibody titres (> 0.5 IU/mL) at 4 weeks (median: 2.1 IU/mL; inter quartile range [IQR]: 0.6–5.7) and 10 jackals had at 12 weeks (median: 3.5 IU/mL; IQR: 1.5–8.3) and three maintained antibody titres for up to 48 weeks (median: 3.4 IU/mL; IQR: 2.0–6.3). Four sites were baited with Raboral V-RG® vaccine for wild jackals, using fishmeal polymer and chicken heads. Baits were distributed by hand or from vehicle at three sites in north-eastern South Africa, with an average baiting density of 4.4 baits/km² and at one site in central South Africa, at 0.12 baits/km². This resulted in protective antibody titres in 3/11 jackals (27%; 95% Cl: 6–61) trapped between 3 and 12 months after baiting in north-eastern South Africa, compared with 4/7 jackals (57%; 95% Cl: 18–90) trapped after 3–18 months in central South Africa. This study shows the potential utility of oral rabies vaccination for the control of wildlife-associated rabies in north-eastern and central South Africa, but extensive studies with wider distribution of bait are needed to assess its potential impact on rabies control in wild jackals.     

Respiration pattern and microbial use of field-grown transgenic Bt-maize residues

A 49-day incubation experiment was carried out with the addition of field-grown maize stem and leaf residues to soil at three different temperatures (5, 15, and 25 °C). The aim was to study the effects of two transgenic Bt-maize varieties in comparison to their two parental non-Bt varieties on the mineralization of the residues, on their incorporation into the microbial biomass and on changes in the microbial community structure. The stem and leaf residues of Novelis-Bt contained 3.9 μg g⁻¹ dry weight of the Bt toxin Cry1Ab and those of Valmont-Bt only 0.8 μg g⁻¹. The residues of the two parental non-Bt varieties Nobilis and Prelude contained higher concentrations of ergosterol (+220%) and glucosamine (+190%) and had a larger fungal C-to-bacterial C ratio (+240%) than the two Bt varieties. After adding the Bt residues, an initial peak in respiration of an extra 700 μg CO₂-C g⁻¹ soil or 4% of the added amount was observed in comparison to the two non-Bt varieties at all three temperatures. On average of the four varieties, 19-38% of the maize C added was mineralized during the 49-day incubation at the three different temperatures. The overall mean increase in total maize-derived CO₂ evolution corresponded to a Q₁₀ value of 1.4 for both temperature steps, i.e. from 5 to 15 °C and from 15 to 25 °C. The addition of maize residues led to a strong increase in all microbial properties analyzed. The highest contents were always measured at 5 °C and the lowest at 25 °C. The variety-specific contents of microbial biomass C, biomass N, ATP and adenylates increased in the order Novelis-Bt ? Prelude<Valmont-Bt ? Nobilis. The mineralization of Novelis-Bt residues with the highest Bt concentration and lowest N concentration and their incorporation into the microbial biomass was significantly reduced compared to the parental non-Bt variety Nobilis. These negative effects increased considerably from 5 to 25 °C. The transgenic Bt variety Valmont did not show further significant effects except for the initial peak in respiration at any temperature.     

Ripening reduces the shrinkage of processed dredged material

Purpose

The utilization of dredged material in dike construction as a substitute for traditionally used materials is considered as an option to preserve natural resources such as marsh sediments. As a prerequisite for this application, the equivalency with respect to soil physical and mechanical properties of the materials must be assessed. Previous investigations have shown pronounced differences in shrinkage behavior and desiccation cracking between sediments and dredged material. The key objective of the study was to assess whether shrinkage of processed dredged material can be reduced by further processing, i.e., dewatering, which can be referred to as ripening.

Materials and methods

To compare the shrinkage behavior of the materials, three different methods of different scales were applied. Small-scale methods conducted were the standard procedure for the determination of the shrinkage limit and the determination of the coefficient of linear extensibility (COLE_rod). Large-scale shrink-swell experiments were carried out in a specially constructed test system with 90 l capacity for a period of up to 385 days. Here the materials were ripened, i.e., air-dried, until shrinkage almost ceased, and a rewetting-air-drying cycle was conducted. Shrinkage and swelling were determined during the processes by measuring the changes in volume. On the ripened materials, COLE_rod was determined.

Results and discussion

The experiments show that the shrinkage behavior of processed dredged material can be ameliorated by ripening. COLE_rod of the ripened materials were about 20–80% lower than COLE_rod of the un-ripened materials. The large-scale shrink-swell experiments showed that shrinkage in the second drying cycle amounted to less volume than in the first drying cycle and that shrinkage behavior in contrast to the first drying cycle, where pronounced proportional shrinkage was observed, was dominated by structural and residual shrinkage in this cycle.

Conclusions

Ripening of processed dredged material is considered a useful pre-treatment option to ameliorate the shrink-swell behavior of processed dredged material and to obtain a better functional equivalency with traditionally used dike construction materials such as fine-grained marsh sediments.