Evaluation of the bioavailability of the herbicide prosulfocarb through adsorption on soils and model soil colloids, and through a simple bioassay

Adsorption isotherms of prosulfocarb were determined on soils with different physicochemical properties. The extent of adsorption increased with the organic carbon content, but the results also suggested the involvement of some inorganic soil surfaces. In order better to understand the role of each soil surface, adsorption-desorption isotherms were determined on model soil colloids consisting of a soil humic acid, a montmorillonite, a synthetic aluminium hydroxide and their associations. The highest adsorption was observed on the humic acid, but it was also confirmed that the montmorillonite interacted with prosulfocarb. In contrast, the aluminium hydroxide was not active and its association with montmorillonite provoked a decrease in adsorption compared with montmorillonite alone. Except for humic acid, the highest adsorption took place on the ternary association montmorillonite-aluminium hydroxide-humic acid. On each surface tested, the adsorption was largely reversible and decreased at increasing pH. The herbicidal activity of prosulfocarb was tested by the determination of the germination and growth of a typical weed, Lolium multiflorum Lam, in contact with prosulfocarb solutions at different concentrations. The herbicide did not prevent the germination of the seeds but inhibited the growth of the roots and leaves. The same test was performed in the presence of the ternary system to evaluate the influence of adsorption on the plant bioavailability. It was concluded that the presence of an adsorptive surface reduced the herbicidal activity and that the simple bioassay proposed could be useful in predicting the extent of adsorption in a given soil.     

Molecular identification of Cryptosporidium spp. from fecal samples of felines, canines and bovines in the state of São Paulo, Brazil

The objective of this study was to obtain information of epidemiological nature through genotypic characterization of Cryptosporidium isolates from dogs, cats and bovines from the state of São Paulo, Brazil. The extraction of DNA from oocysts was carried out and polymerase chain reaction was accomplished using specific primers to 18S rRNA gene. The amplicons were directed sequenced. Seven cat samples, nine dog samples and nine bovine samples were analysed. From the seven cat samples the genotypic analyses revealed Cryptosporidium felis in all. These were the first genotypic characterization of Cryptosporidium from domestic felines in Brazil. In nine sequenced samples from dogs, genotypic identities compatible with Cryptosporidium canis were revealed in all samples. The genotypic analyses in bovines revealed Cryptosporidium parvum in eight samples and Cryptosporidium bovis in another sample, the last one being a non-zoonotic species, not related to clinical symptoms and described for the first time in Brazil.     

Occurrence of antibodies to Toxoplasma gondii and Lepstospira spp. in manatees (Trichechus inunguis) of the Brazilian Amazon

The presence of Toxoplasma gondii and Leptospira spp. antibodies was investigated in 74 manatees (Trichechus inunguis [Mammalia: Sirenia]) kept in captivity in two rescue units in the northern region of Brazil. Antibodies to T. gondii were detected in 29 (39.2%) of 74 animals by using the modified agglutination test (titer, 1:25). For antibodies against Leptospira spp., sera were diluted 1:50 and tested against 24 strains ofleptospires by microscopic agglutination microtechnique, and positive samples were end titrated. Twenty-three (31.1%) of 74 animals were reactive to four serovars (Patoc 21/23, Castellonis 2/23, Icterohaemorrhagiae 1/23, and Butembo 1/ 23), with titers ranging from 100 to 1,600. This is the first report of antibodies against T. gondii and Leptospira spp. in T. inunguis from the Brazilian Amazon.     

Isoenzyme analysis of Haemonchus contortus resistant or susceptible to ivermectin.

Three different strains of Haemonchus contortus (susceptible to ivermectin, S-IVM; selected for resistance to ivermectin, R-IVM; a multiple resistant strain, i.e. resistant to benzimidazole and ivermectin, R-IVM/SA) were examined for isoenzyme variation by starch gel electrophoresis. Using stains for seven enzymes separated in five different buffer systems, no differences in the electrophoretic mobility could be detected between any of the strains. Results demonstrate a low level of enzyme variation in H. contortus and no differences in enzyme electrophoretic profile between IVM-sensitive and IVM-resistant parasites. Differences between the ivermectin-sensitive and both ivermectin-resistant strains were observed with the propionyl esterases and although some of the differences are probably associated with benzimidazole resistance, others are associated with resistance to ivermectin. The three strains of H. contortus are generally identical; however, differences between all strains of H. contortus and a strain of Dictyocaulus viviparus were detected.     

Prevalence of <Emphasis Type="Italic">Toxoplasma gondii</Emphasis> and <Emphasis Type="Italic">Neospora caninum</Emphasis> infections in sheep from Federal District,central region of Brazil

Serum samples from 1028 sheep were collected from 32 herds within Federal District, in the central region of Brazil. The samples were examined by indirect fluorescent antibody test (IFAT) using sera diluted 1:64 and 1:50 as cut-off values for the detection of antibodies against Toxoplasma gondii and Neospora caninum, respectively. The observed prevalence for T. gondii infection was 38.22% (26.81%<CI 0.95<49.62%), and the titers ranged from 64 to 65536. The observed prevalence for N. caninum infection was 8.81% (7.08%<CI 0.95<10.53%). The titers ranged from 50 to 51200. The reactant sera to both pathogens corresponded to 4.67% of the samples. The risk factors were not determined because of the absence of negative herds for T. gondii and the high proportion of positive herds for N. caninum (87.50%). The prevalence for T. gondii infection was significantly higher among males than in females. The present work is the first report on seroprevalence of T. gondii and N. caninum in sheep from Federal District and shows that infection by both parasites is widespread in the ovine population from this region.     

Longitudinal assessment of the impact of aging on wastage,productivity and welfare of ewes

Retention of aging ewes is a strategy producers may use to maintain or increase flock size. Older ewes can have a higher risk of mortality and health issues, but these may be minimised with early intervention and culling. This retrospective study examined the incidence and causes of mortality and culling in a flock of Merino ewes as they aged from 4.5 to 5.5 until 9.5 to 10.5 years. The annual rate of ewe mortality ranged from 6.2% to 9.9%, with lambing complications being the major source of reported loss. Annual culling rates ranged from 1.6% to 42.8%, the larger rates reflecting opportunistic replacement with younger ewes rather than essential culling to maintain welfare and productivity. The major reasons for culling were low condition score, worn or missing teeth or faulty udders. The incidence of other faults was low. Only 18.3% of ewes remained when aged 9.5–10.5 years and these were fertile (89% pregnant) with a high proportion of multiple fetuses (52%) in their final year, although fleece weight had declined. Younger ewes born in 2004/2005 tended to have lower annual mortality rates than the aged ewes, but 8%–12% were still culled annually. It is concluded that an annual inspection pre-joining of all ewes and preventative culling for health issues is necessary to minimise any increase in mortality and risk to ewe welfare from retaining aging ewes. More frequent inspection will be required as potential health issues develop during the year, as these may not be evident pre-joining.     

Serological survey of Leishmania infantum and Trypanosoma cruzi in dogs from urban areas of Brazil and Colombia

Leishmania infantum and Trypanosoma cruzi are zoonotic parasites that are endemic throughout many parts of Latin America. Infected dogs play an important role in transmission of both parasites to humans. A serological survey of Leishmania and Trypanosoma infection was conducted on 365 dogs from S?o Paulo, Brazil and Bogatá, Colombia, South America. Serum samples were examined by the indirect immunofluorescent antibody test (IFAT). Anti-Leishmania IgG antibodies were detected in 5 of 107 from Brazil (4.7%) and in 4 of 258 dogs (1.6%) from Colombia. Titers ranged from 1:25 to 1:100. Anti-T. cruzi antibodies were not detected in any of the dogs from either Brazil or Colombia. The results show a low prevalence of anti-Leishmania antibodies and no antibodies against T. cruzi in these canine populations. Our study suggests that dogs play a limited role in the spread of L. infantum and T. cruzi in these urban areas of Brazil and Colombia.     

Ultrasound during mid‐gestation: Agreement with physical foetal and placental measurements and use in predicting gestational age in sheep

To determine the effects of poor maternal nutrition and litter size on foetal growth during mid‐gestation, pregnant ewes (n = 82) were fed 100%, 60% or 140% of NRC TDN beginning at day 30.2 ± 0.2 of gestation. Transabdominal ultrasound was performed weekly between day 46.0 ± 0.4 and 86.0 ± 0.7 to monitor foetal heart width (HW), umbilical diameter (UMB), rib width (RW) and placentome outer (OD) and inner diameter (ID). Data were analysed with repeated‐measures using the mixed procedure for effects of maternal diet, litter size and gestation, and equations predictive of gestational age were generated using the regression procedure. To determine the agreement of ultrasound measurement and actual size, ewes (n = 20–21) were euthanized at day 45 or 90 to obtain corresponding postmortem measurements for Bland–Altman analysis. The HW, UMB and placentome OD and ID increased with gestation (p < .0001) but were unaffected by maternal diet or litter size (p ≥ .12). Ultrasound underestimated postmortem measurements of HW (14.8%), UMB (7.3%), placentome OD (4.5%) and ID (37.3%) at day 90 of gestation. Ultrasound underestimated RW at day 45 (7.7%) but overestimated RW (23.8%) at day 90, indicating inconsistent bias when reporting RW by ultrasound. Combining the HW, UMB, RW and placentome OD generated the strongest equation predictive of gestational age (R² = .91). These findings indicate that during mid‐gestation, maternal diet or litter size did not affect HW, UMB or placentome diameters and these factors can be used to estimate gestational age.     

Influence of protein supplementation on the resistance and resilience on young hair sheep naturally infected with gastrointestinal nematodes during rainy and dry seasons

Thirty, 4-month-old entire Santa Ines lambs were grazed on an Andropogon gayanus pasture, during a 34-week period (rainy season weeks 0-20 and dry season weeks 21-34) and allocated in two treatment groups (n = 15) each with different protein supplementation: high protein (HP-19% CP) and low protein (LP-11% CP). These were subdivided into those receiving anthelmintic treatment (c) (n = 7) and without anthelmintic treatment (i) (n = 8). The objective was to evaluate the effects of supplementation with protein on resistance and resilience to natural helminth infection of hair breed lambs. Lamb weight, blood collection and faecal egg counts (FEC) were carried out monthly. The lambs were slaughtered after 34 weeks, when worm burdens, worm length and eosinophil cell counts were taken. The sheep on treatments HPc and HPi were heavier in live weight than those from LPi and LPc (P < 0.05) at the end of the rainy period. The HPc group finished heavier (P < 0.05) than the other groups in the dry season, which had no significant differences between them. The predominant species of nematode found was T. colubriformis followed by H. contortus, Trichuris globulosa and Moniezia expansa. Animals on HPi had lower FEC than LPi (P < 0.05). The number of worms was lower for both HP groups (P < 0.05) with worm length shorter in the HPc group (P < 0.05) compared with all other groups. The number of eosinophils was higher in animals in the LPi group, which also showed anaemia and lower plasma urea at the end of the dry season. Diet supplementation with high protein was able to improve resilience and resistance to natural infection by endoparasites during the rainy season. In the dry season there was a decrease in both of these traits, which were intimately linked to the quality of available forage under tropical conditions.     

Identification of galegine, an isoprenyl guanidine, as the toxic principle of Schoenus asperocarpus (poison sedge)

SUMMARY An Isoprenyl guanldine, galegine, was isolated from the Western Australian sedge Schoenus asperocarpus (Cyperaceae). Synthetic galegine was shown to reproduce the clinical and pathological features of poisoning by this plant. Preliminary results suggest that the massive thoracic effusion observed in sedge poisoning is the result of a direct effect on pulmonary vascular permeability.