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A study was conducted to record the deaths that occurred during export, and to examine the temporal pattern of pellet feeding in the feedlot and ascertain the variation in mortality between groups of sheep from different farms. Between November 1985 and April 1987, 5 cohorts of sheep were selected on arrival at a feedlot before live export by sea from Western Australia to the Middle East. Each cohort consisted of 4,118 to 9,612 Merino wethers from 15 to 35 farms (lines). There were few deaths during trucking to the feedlot (rate 0.9, range 0.0 to 3.0 per 10,000 sheep) and during lot-feeding (rate 6.2, range 1.2 to 12.2 per 10,000 sheep). Most of the deaths occurred aboard ship (rate 210.7, range 152.7 to 271.5 per 10,000 sheep). The proportion of sheep that ate pelleted feed increased with increasing length of time in the feedlot. By the end of lot-feeding the percentage of sheep that had not eaten pellets was 23.3, 4.4, 1.2, 2.1 and 0.2 in a representative sample of each of the 5 cohorts. It was considered that offering hay throughout lot-feeding was undesirable for the purpose of maximising the number of sheep that ate pellets before loading on the ship. Half of the deaths aboard ship occurred in 25% of 133 lines of sheep in the 5 cohorts. In each cohort the median per cent death rate (and range) per line was 1.3 (0.3 to 11.9), 1.1 (0.0 to 5.7), 1.8 (0.0 to 6.8), 2.3 (0.0 to 14.3) and 0.9 (0.1 to 5.4).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Integrated optoelectronic devices based on conjugated polymers 总被引:1,自引:0,他引:1
An all-polymer semiconductor integrated device is demonstrated with a high-mobility conjugated polymer field-effect transistor (FET) driving a polymer light-emitting diode (LED) of similar size. The FET uses regioregular poly(hexylthiophene). Its performance approaches that of inorganic amorphous silicon FETs, with field-effect mobilities of 0.05 to 0.1 square centimeters per volt second and ON-OFF current ratios of >10(6). The high mobility is attributed to the formation of extended polaron states as a result of local self-organization, in contrast to the variable-range hopping of self-localized polarons found in more disordered polymers. The FET-LED device represents a step toward all-polymer optoelectronic integrated circuits such as active-matrix polymer LED displays. 相似文献
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AA Zakhidov RH Baughman Z Iqbal C Cui I Khayrullin SO Dantas J Marti VG Ralchenko 《Science (New York, N.Y.)》1998,282(5390):897-901
Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials. 相似文献
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Recently-gathered information relating to the abundance and distribution of the asteroid Acanthaster planci on coral reefs at various localities in the Indo-West Pacific region is presented. Since 1957, population explosions of this coral predator have been observed on reefs in widely-separated areas. The infestations appear to be on an unprecedented scale. In some regions the area of reefs affected has increased progressively during the last decade. The principal infestations have occurred on accessible reefs near centres of human population, while remote reefs appear to be free from A. planci infestations. Human involvement in the initiation of the infestations is suggested. 相似文献
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FL BOWEN P FISARA P JUNQUERA DT KEEVERS RH MAHONEY HR SCHMID 《Australian veterinary journal》1999,77(7):454-460
OBJECTIVE: To assess a ready-to-use formulation of dicyclanil to prevent blowfly strike on Merino sheep under Australian conditions. DESIGN: Randomised clinical trials conducted in an environment house and in the field. PROCEDURE: Two environment house trials were used to measure the protection against flystrike provide by a jetting or a ready-to-use 5% spray-on formulation of dicyclanil over 22 and 31 weeks respectively. Oviposition and strikes were recorded weekly for each sheep. In two field trials the occurrence of strike in Merino sheep treated off-shears or in long wool with dicyclanil or with cyromazine was compared for up to 38 weeks after treatment. Efficacy was assessed by calculating the cumulative percentage of sheep struck. RESULTS: Under environment house conditions, sheep jetted with dicyclanil at 1.50, 0.75 and 0.30 g per sheep developed 0, 8 and 9 strikes respectively during the 22 weeks of the trial, whereas there were 358 strikes present in the placebo group. Sheep sprayed with dicyclanil at 2.25, 1.50 and 0.75 g per sheep developed 5, 11 and 29 strikes respectively between weeks 15 and 31 after treatment, whereas there were 185 strikes present in the untreated controls. In field trials the cumulative percentage of sheep struck reached 1% between weeks 12 to 13 after sheep had been treated with cyromazine. Sheep treated with dicyclanil reached the 1% limit at week 21 after treatment. CONCLUSION: Under Australian field conditions, a ready-to-use 5% spray-on formulation of dicyclanil applied off-shears or to long wool protected Merino sheep from blowfly strike for a period of at least 20 weeks. 相似文献
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XY Zeng JA Turkstra DFM van de Wiel DZ Guo XY Liu RH Meloen WMM Schaaper FQ Chen HB Oonk & X Zhang 《Reproduction in domestic animals》2001,36(2):101-105
We have investigated, under the normal conditions of local Chinese pig farming, castration of young male pigs by vaccination with a newly developed vaccine against gonadotrophin releasing hormone (GnRH). Because of the very early onset of puberty, long fattening period and relatively harsh circumstances in Chinese pig production, an investigation of the endocrine response of Chinese breeds to this type of vaccination was of particular interest. Fifteen crossbred boars (Yorkshire × Yanan) from three different litters were randomly assigned to three groups of five animals each. The first group was immunized at 13 weeks of age with a GnRH tandem dimer OVA‐conjugate in Specol and received a booster immunization 8 weeks later. The second group was injected with Specol alone and served as untreated controls. The remaining group was surgically castrated at the time of weaning (at 6 weeks of age). Pigs were fed ad libitum from weaning onwards. All animals were slaughtered at 31 weeks of age. Immunized boars had undetectable or low serum testosterone (0.09 ± 0.12 ng/ml), low fat androstenone (0.05 ± 0.01 μg/g) levels and very low testes weights (19.1 ± 4.3 g). Intact controls had much higher serum levels of testosterone (9.76 ± 4.81 ng/ml), fat androstenone levels (2.26 ± 0.87 μg/g) and testes weights (114.3 ± 29.41 g) at slaughter. Both the immunized and castrated group grew significantly faster than intact boars (p < 0.01). Average daily gains in immunized, castrated and intact animals were 0.69 ± 0.08, 0.63 ± 0.05 and 0.42 ± 0.07 kg (mean ± SD), respectively. The present data demonstrate for the first time that the newly developed anti‐GnRH vaccine works very well under practical Chinese pig farming conditions, and can be an attractive alternative to surgical castration. 相似文献
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The effects of allopurinol on the ultrastructure of ischaemic and reperfused large intestine of sheep 总被引:1,自引:0,他引:1
M AHMADINEJAD MAE REX RH SUTTON CC POLLITT B CRIBB 《Australian veterinary journal》1996,74(2):135-139
Objective To test the possible inhibitory effect of allopurinol on reperfusion injury, caused by oxygen-derived free radicals, of sheep large intestine.
Design An ultrastructural study on caecal tissues from control and treated groups.
Fifty sheep in four ischaemic and reperfused (treatment) groups and one control group. Three of the treatment groups were subdivided for half to be injected with allopurinol and the other half with its solvent, potassium hydroxide (KOH).
Procedure Ischaemia of the caecum was induced in the four treatment groups for 60 minutes by clamping the apex. Allopurinol and its KOH solvent were injected intravenously in three treatment groups prior to ischaemia. Samples were collected before and 1 hour after induction of ischaemia and 1 min, 1 h and 8 h after reperfusion. Tissues were processed and examined with an electron microscope.
Results Untreated and solvent injected sheep showed minor ultrastructural changes following ischaemia. With reperfusion, there was severe mitochondrial, goblet cell and basement membrane damage. Tissues from allopurinoltreated sheep were preserved and appeared similar to tissues from the control group.
Pre-treatment with allopurinol prevented damage to tissues whereas untreated or allopurinol solventtreated showed severe damage following reperfusion. It is believed that allopurinol, an analogue of hypoxanthine and xanthine, prevents reperfusion injury by competitively binding with xanthine oxidase. This reduces or inhibits the xanthine oxidase mediated conversion of hypoxanthine to xanthine thereby preventing the formation of oxygen-derived free radicals. 相似文献
Design An ultrastructural study on caecal tissues from control and treated groups.
Animals
Fifty sheep in four ischaemic and reperfused (treatment) groups and one control group. Three of the treatment groups were subdivided for half to be injected with allopurinol and the other half with its solvent, potassium hydroxide (KOH).
Procedure Ischaemia of the caecum was induced in the four treatment groups for 60 minutes by clamping the apex. Allopurinol and its KOH solvent were injected intravenously in three treatment groups prior to ischaemia. Samples were collected before and 1 hour after induction of ischaemia and 1 min, 1 h and 8 h after reperfusion. Tissues were processed and examined with an electron microscope.
Results Untreated and solvent injected sheep showed minor ultrastructural changes following ischaemia. With reperfusion, there was severe mitochondrial, goblet cell and basement membrane damage. Tissues from allopurinoltreated sheep were preserved and appeared similar to tissues from the control group.
Conclusion:
Pre-treatment with allopurinol prevented damage to tissues whereas untreated or allopurinol solventtreated showed severe damage following reperfusion. It is believed that allopurinol, an analogue of hypoxanthine and xanthine, prevents reperfusion injury by competitively binding with xanthine oxidase. This reduces or inhibits the xanthine oxidase mediated conversion of hypoxanthine to xanthine thereby preventing the formation of oxygen-derived free radicals. 相似文献
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JG Besso DEDV RH Wrigley BVSc MS DVR JM Gliatto VMD CRL Webster DVM 《Veterinary radiology & ultrasound》2000,41(3):261-271
Fourteen dogs with enlarged gallbladders and immobile stellate or finely striated bile patterns on ultrasound are described. Smaller breeds and older dogs were overrepresented, with 4/14 Cocker Spaniels. Most dogs presented for nonspecific clinical signs such as vomiting, anorexia and lethargy. Abdominal pain, icterus and hyperthermia were the most common findings on physical examination. All dogs except one had serum elevation of total bilirubin and/or alkaline phosphatase, alanine aminotransferase and gamma glutamyl transferase. All dogs were diagnosed with a gallbladder mucocele upon histologic and/or macroscopic evaluation. Ultrasonographically, mucoceles are characterized by the appearance of the stellate or finely striated bile patterns and differ from biliary sludge by the absence of gravity dependent bile movement. On ultrasound, gallbladder wall thickness and wall appearance were variable and nonspecific. The cystic or common bile duct were normal sized in 5 dogs although all 5 had evidence of biliary obstruction at surgery or necropsy. Loss of gallbladder wall integrity and/or gallbladder rupture were present in 50% of the dogs, all located in the fundus. Gallbladder wall discontinuity on ultrasound indicated rupture whereas neither bile patterns predicted the likelihood of gallbladder rupture. Pericholecystic hyperechoic fat or fluid were suggestive of but not diagnostic for a gallbladder rupture. Cholecystectomy appears to be an appropriate treatment for mucoceles, if not to treat a gallbladder rupture, at least in most dogs to prevent it since gallbladder wall necrosis was identified by histology in 9 of 10 dogs. Mucosal hyperplasia was present in all gallbladders examined histologically. Positive aerobic bacterial culture was obtained from bile in 6 of 9 dogs. Cholecystitis was diagnosed histologically in 5 dogs and 4 dogs had signs of gallbladder infection solely upon bacterial bile culture. Gallbladder infection was not present with all the mucoceles suggesting that biliary stasis and mucosal hyperplasia may be the primary factors involved in mucocele formation. Based on the results of our study, we suggest two alternate courses of action in the presence of a distended gallbladder with an immobile ultrasonographic stellate or finely striated bile pattern: a cholecystectomy when clinical or biochemical signs of hepatobiliary disease are present or a medical treatment (antibiotics and choleretics) and patient monitoring by follow-up ultrasound examinations when the patient does not have clinical or biochemical abnormalities. An aerobic bile culture should be obtained in all patients, by ultrasound-guided fine needle aspirate or at surgery. 相似文献