Active Immunization against Gonadotrophin-releasing Hormone in Chinese Male Pigs

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.     

Improving predictions of forest growth using the 3-PGS model with observations made by remote sensing

Measurements made by remote sensing can characterize the leaf area density and nitrogen/chlorophyll content of forest canopies, as well as maximum photosynthetic capacity and above-ground structure and biomass. Combining these with climate data estimated from relationships based on temperature measurements and using an appropriate process-based model, it is possible to calculate, with useful accuracy, carbon sequestration and wood production by different forest types covering large land areas. To broaden its application and reduce the need for detailed information on stand characteristics, a satellite-driven version of the model 3-PG, was developed. The 3-PGS model incorporates the major first-order physiological processes that determine forest growth, and the biophysical factors that affect and govern those processes. It incorporates remotely sensed estimates of seasonal variation in canopy light interception (fPAR) and includes physiological variables (stomatal conductance and canopy quantum efficiency) that can be estimated by remote-sensing measurements of factors that influence those variables. 3-PGS therefore provides a useful framework within which to evaluate how data from the array of airborne and satellite-borne sensors now available might be used to initialize, drive, and test process-based growth models across regions with diverse soils and climates. We address the question: to what extent might additional remote-sensing techniques improve 3-PGS predictions?Sensitivity analyses indicate that model accuracy would be most improved through better estimates of seasonal changes in canopy photosynthetic capacity (α) and canopy conductance (G_c). Canopy photosynthetic capacity depends on the amount of light absorbed by the canopy, estimated as a fraction of photosynthetically active radiation (fPAR), and on foliage nitrogen or chlorophyll content, which can be estimated using multi-spectral imagery. G_c depends on canopy leaf area index (L) and stomatal conductance of the foliage (g_s), which is affected by the vapor pressure deficit of the air and soil water content. The onset and effects of drought can be determined from changes in canopy reflectance and fPAR identified from sequential measurements; the same measurements, coupled with calculations of evapotranspiration using climatic data and standard formulae, provide estimates of total available water in forest root zones. Periodic surveys with Light Detection and Ranging (LiDAR) and interferometric RADAR may serve to validate model predictions of above-ground growth (NPP_A), while progressive reduction in light-use efficiency (NPP_A/APAR) may identify forests with declining vigor that are likely to succumb to attack from insects and pathogens.     

Long-lasting prevention against blowfly strike using the insect growth regulator dicyclanil

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.     

ULTRASONOGRAPHIC APPEARANCE AND CLINICAL FINDINGS IN 14 DOGS WITH GALLBLADDER MUCOCELE

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.     

The metabolism of mebenil in rats,rabbits and guinea-pigs

The metabolism of mebenil (o-toluanilide) was studied in rats, rabbits and guinea-pigs. The major metabolite in all three species was 4′-hydroxy-o-toluanilide, both free and as glucuronide and sulphate conjugates. Traces of aniline were also excreted, showing that the amide bond was hydrolysed in vivo.     

Plant moisture stress: evaluation by pressure bomb

The recently developed technique for determining the water stress of a plant by measuring the pressure necessary to force water back to the cut surface of a severed twig is adaptable to both field and laboratory experiments. We have designed and operated an efficient portable system weighing less than 18 kilograms. Sampling variation within and among Douglas fir trees varies from less than +/- I atmosphere under low stress conditions to +/- 10 atmospheres under high stress conditions. In the measurement of plants of comparable height and similar exposure, the variation is reduced to a minimum. Values in internal water stress of Douglas fir vary from 3 to more than 40 atmospheres. Both duration and magnitude of stress are important ecologically. Pressure-bomb measurements are used to demonstrate a relation between plant distribution and internal water stress.     

The nutritive value of fish meal, meat-and-bone meal and field bean meal as measured by digestibility experiments on the adult colostomised fowl

Digestibility experiments were carried out, using colostomised hens fed semi‐synthetic diets containing fish meal, meat‐and‐bone meal or field bean meal as the sole source of protein. A “nitrogen‐free” diet was fed to one group of three birds.

Metabolic faecal nitrogen (MFN) output of birds consuming about 75 g dry matter/d was 106 mg/d. The amino acid composition of the MFN was determined. Endogenous urinary nitrogen output (one result) was 0.80 mg Wg0–75/d.

The true digestibilities of the crude protein of fish meal, meat‐and‐bone meal and field bean meal were respectively 89, 69 and 83 per cent. Digestibility coefficients of individual amino acids were also determined and it was found that the amino acids were not equally digestible. However, for each protein source most of the coefficients fell within a range of + 5 per cent of the mean.

The metabolisable energy content of the fish meal was 2645 kcal/kg, meat‐and‐bone meal 1988 kcal/kg and field beans 2910 kcal/kg.     

The metabolism of cis-2,5-dimethylpyrrolidine-1-carboxanilide in rodents

The metabolism of cis-2,5-dimethylpyrrolidine-1-carboxanilide was studied in rats, rabbits, guinea-pigs and mice. The major metabolite in all species was cis-4′-hydroxy-2,5-dimethylpyrrolidine-1-carboxanilide, both free and as glucuronide and sulphate conjugates. About 95% of the compound was absorbed from the gut; over a 3-day period, about 50% of the administered dose was excreted in urine and about 27% in faeces.     

The effects of allopurinol on the ultrastructure of ischaemic and reperfused large intestine of sheep

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.  

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.     

Imbalanced forest ecosystems: Assessments and consequences

Few ecosystems can maintain an ideal balance of available resources for primary producers, decomposing organisms, and consumers. When nutrition is optimal for plants, their tissue may be toxic for many consumers and their detritus nutritionally imbalanced for decomposers. Even conditions favoring high rates of primary production soon lead to limitation in light and possibly other resources. Because of the integrated nature of ecosystems, stress induced in one part permeates the entire system. With chronic stress induced by climatic change or air pollution, we might expect reductions in canopy leaf area, decomposition rates, and root mineral uptake, and increases in herbivory, pathological activity, and leaching of material into or through the rooting zone. Each of the six responses can be simply assessed. As a general index of stress to forest ecosystems, we may monitor changes in the ability of folaige to produce wood. Below a particular level of production, trees become susceptible to a variety of insects and diseases. Through an experimental approach, we can identify the relative importance of constraining factors and predict the consequences of management options.