Cultivation and drainage performance on former opencast coal mining land

Abstract. The effect of various cultivation sequences on the performance of field drainage systems was investigated in a number of case studies carried out on former opencast coal mining land. Comparisons of drain flow patterns before and after cultivation indicated marked deteriorations in performance following preparation of the final seedbed. Neither mouldboard ploughing nor discing alone affected drain flow.
Soil moisture, hydraulic conductivity and drain flow data suggested that drainage performance may have deteriorated as a result, initially, of secondary drainage channels being blocked with fine materials translocated from the seedbed. A subsequent collapse of tilth to form a surface pan reinforced this adverse effect. It was not clear to what extent the failure of secondary drainage channels contributed to this collapse.
Implications for the management of former opencast land and the advantages of various cultivation techniques are discussed.     

Prevalence of Mycoplasma gallisepticum and M. synoviae in commercial layers in southern and central California

The prevalence of Mycoplasma gallisepticum (MG) and M. synoviae (MS) in commercial pullet and layer flocks in Southern and Central California was estimated by testing serum and egg-yolk samples from 360 sample flocks in Southern California and 41 sample flocks in Central California. Data relating to potential risk factors associated with MG and MS infections were collected. The estimated true prevalence rate of MG was 73% in Southern California and 3% in Central California. The estimated true prevalence rate of MS was 91% in Southern California and 32% in Central California. Compared with uninfected flocks, MG-infected flocks in Southern California were significantly older and were medicated less (P less than 0.05). More managements were under a multiple-age system, more flocks had molted, more were vaccinated with F-strain, and more had concurrent infection with MS (P less than 0.05). Only one sample flock in Central California was MG-infected; none were vaccinated with F-strain. In Southern California, MS-infected flocks were older than uninfected flocks, more had molted, more were medicated, and more had concurrent infection with MG (P less than 0.05). In Central California, MS-infected flocks did not differ significantly from uninfected flocks in any factor examined; the lack of statistical significance may be due to small sample size.     

A survey of gastro intestinal helminth parasites of stray dogs in Zaria, Nigeria.

A survey of helminth parasites in stray dogs was carried out in the Zaria area. Out of 180 dogs examined 65.6 per cent (118/180) were found positive for Ancylostoma caninum, while Toxocara canis and Trichuris vulpis were detected in 41.1 per cent (74/180) and 13.9 per cent (25/180) respectively. Other helminth parasites found Taenia ovis 35 per cent (63/180) Taenia hydatigena 67.8 per cent (122/180), Echinococcus granulosus 0.006 per cent (1/180) and Dipylidium caninum 97.8 per cent (176/180).     

The epidemiology of echinococcus infection in Kaduna State, Nigeria

Infection of dogs with Echinococcus gramulosus is recorded for the first time in Kaduna State. Observations on 330 dogs from different suburbs revealed an incidence of 1.2 per cent. Of slaughtered stock examined, hydatid cyst infections were found in sheep (7.1 per cent), goats (18.4 per cent), cattle (1.5 per cent), camels (70.9 per cent) and pigs (5 per cent).     

Serum gamma glutamyl transferase activity in horses with right or left dorsal displacements of the large colon

The purpose of this study was to test the hypothesis that horses with right dorsal displacement of the large colon (RDDLC) have elevations in serum gamma glutamyl transferase (GGT) activity when compared with horses with left dorsal displacement of the large colon (LDDLC). Medical records from 37 horses with RDDLC and 48 horses with LDDLC were reviewed. Horses were included for study if the RDDLC or LDDLC was confirmed by exploratory laparotomy or postmortem examination and if a serum GGT measurement was obtained within 24 hours before surgery. The proportion of horses with GGT activity within or above the reference range was determined. Of 37 horses, 18 (49%; exact binomial 95% confidence interval, 32-66%) with RDDLC and, of 48 horses, 1 (2%; 95% CI, 0-11%) with LDDLC had GGT above the reference range. Horses with RDDLC had higher serum GGT than did horses with LDDLC. Of 37 horses, 36 (97%) with RDDLC were discharged with a good prognosis and none returned as a result of hepatic disease. Evaluation of surgical and postmortem examinations revealed that positioning of the colon in horses with RDDLC results in compression of the bile duct, which can cause extrahepatic bile duct obstruction and a subsequent elevation in serum GGT activity.     

Molecular characterization of potentially zoonotic isolates of Giardia duodenalis in horses

Giardia isolates from eight horses from New York State (NY), USA and two horses from Western Australia (WA) were genetically characterized at the SSU-rDNA and triose-phosphate isomerase (TPI) genes. Phylogenetic analysis of the TPI gene provided strong support for the placement of both isolates of Giardia from horses in WA and a single isolate from a horse in NY within the assemblage AI genotype of G. duodenalis. Another two isolates from horses in NY placed within the assemblage AII genotype of G. duodenalis. Phylogenetic analysis of the TPI gene also provided strong bootstrap support for the placement of four G. duodenalis isolates from horses in NY into a potentially host-specific sub-assemblage of assemblage BIV. The results of this study are consistent with previous studies showing that assemblages AI and AII of G. duodenalis provide the greatest potential zoonotic risk to humans. Horses may therefore constitute a potential source for human infection of Giardia either directly or via watersheds.     

Genotype dynamics of Campylobacter jejuni in a broiler flock

We investigated the genotype diversity and dynamics of Campylobacter in a commercial broiler flock during rearing and slaughter. In total, 220 Campylobacter jejuni isolates collected on four sampling occasions during rearing and from routine sampling during slaughter were subtyped by SmaI macrorestriction and pulsed-field gel electrophoresis, PFGE. Eight different SmaI types were found. During rearing, a subsequent addition of genotypes occurred, with two SmaI types found at 2 weeks of age and six types on the day before slaughter. All types that were detected in more than one isolate were also found on all succeeding sampling occasions, including the slaughter sampling. Two new types were found in the slaughter samples. In two-thirds of the individual birds sampled the day before slaughter, more than one SmaI type were found, although there was a clear tendency for dominance of one type in individual birds. Our results show that multiple genotypes of C. jejuni may be present in a commercial broiler flock during rearing and even in gastrointestinal tracts of individual birds. Both recurring environmental exposure and genetic changes within the population may explain the genotype diversity. Although the distribution of genotypes varied between different sampling occasions, we found no indication that any subtype excluded another during the rearing of the broiler flock.     

The contact toxicity of indoxacarb and five other insecticides to Orius insidiosus (Hemiptera: Anthocoridae) and Aphidius colemani (Hymenoptera: Braconidae), beneficials used in the greenhouse industry

The contact toxicity of indoxacarb, abamectin, endosulfan, insecticide soap, S-kinoprene and dimethoate to Orius insidiosus (Say) and Aphidius colemani Viereck were studied in the laboratory. These beneficials are often used in the greenhouses to manage various insect pests. Indoxacarb is slow acting and therefore, to estimate lethal dosages, observations should be continued for several days until data stabilize. Seven days after treatment, the LC50 was 0.119 g AI litre(-1) for O insidiosus adults and 0.019 g AI litre(-1) for A colemani. At that time, the recommended field concentration was 0.479 times the LC50 for O insidiosus adults and three times the LC50 for A colemani. In contrast, indoxacarb had no adverse effect on the reproductive capacity of wasps surviving a treatment or the developing wasps in the aphid mummy. Among the other insecticides S-kinoprene was the most innocuous while dimethoate was the most toxic to the two beneficials. The other insecticides had overlapping toxicities.