Department of Veterinary Biosciences

Bioassay guided fractionation of senna singueana and its potential for development of poultry phytogenic feed additives.

Thu, 13 Jan 2022 00:00:00 GMT

Bioassay guided fractionation of senna singueana and its potential for development of poultry phytogenic feed additives. Jambwa, Prosper; Makhubu, Fikile N.; Matope, Gift; Fouche, Gerda; McGaw, Lyndy J. There has been burgeoning interest in plant-based feed additives following restrictions placed on the use of antibiotic feed additives inmany countries. Phytogenic feed additives are recommended to have a range of useful properties to support the growth and development of poultry to a similar level as that obtained by supplementing feed with antibiotics. The aim of this study was to evaluate the antibacterial, anti lipoxygenase and antioxidant activity, and in vitro safety of fractions and isolated compounds from leaves of Senna singueana. Antibacterial activities of the fractions and isolated compounds were determined against a panel of bacteria using a two-fold serial microdilution assay and qualitative bioautography assays. Anti lipoxygenase activity was evaluated using the ferrous oxidation-xylenol orange (FOX) method. Antioxidant activity was assessed qualitatively and quantitatively using radical scavenging assays. Dichloromethane and ethyl acetate fractions from solvent-solvent partitioning had the best antibacterial activity with MIC values ranging from 156 to 313μg/ml. Fractions obtained from column chromatography had significant to weak antibacterial activity with MIC values ranging from 50 to 1,250μg/ml. Bioautography showed clear bands of bacterial inhibition, indicating the presence of a number of active compounds in several fractions. The ethyl acetate fraction and all the tested column fractions had potent anti-lipoxygenase activity with IC50 values of ≤2.5μg/ml which were lower than that of quercetin (positive control), indicating anti-inflammatory potential. The ethyl acetate fraction and several column fractions had powerful antioxidant activity with IC50 values of≤5μg/ml in the ABTS assay. Cytotoxicity values against Vero kidney cells ranged from LC50 = 40.0–989.3μg/ml. Bioassay-guided fractionation led to the isolation and identification of a known bioactive compound, luteolin. S. singueana is a promising candidate for the development of poultry phytogenic feed additives.

Epidemiological studies of amphistome infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe

Sat, 01 Jan 2005 00:00:00 GMT

Epidemiological studies of amphistome infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe Pfukenyi, Davies Mubika; Mukaratirwa, Samson; Willingham, A.L.; Monrad, J. During the period between January 1999 and December 2000, the distribution and seasonal patterns of amphistome infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe were determined through monthly coprological examination. Cattle faecal samples were collected from 12 and nine dipping sites in the highveld and lowveld communal grazing areas, respectively. Patterns of distribution and seasonal fluctuations of intermediate host-snail populations and the climatic factors influencing the distribution were also determined by sampling at monthly intervals for a period of 24 months (November 1998 to October 2000) in six dams and six streams in the highveld and in nine dams in the lowveld communal grazing areas. Each site was sampled for relative snail density and the vegetation cover and type, physical and chemical properties of water, and mean monthly rainfall and temperature were recorded. Aquatic vegetation and grass samples 0–1 m from the edges of the snail habitats were collected monthly to determine the presence or absence of amphistome metacercariae. Snails collected at the same time were individually checked for the emergence of larval stages of amphistomes. A total of 16 264 (calves 5 418, weaners 5 461 and adults 5 385) faecal samples were collected during the entire period of the study and 4 790 (29.5 %) of the samples were positive for amphistome eggs. For both regions the number of animals positive for amphistome eggs differed significantly between the 2 years, with the second year having a significantly higher prevalence (P < 0.01) than the first year. Significantly higher prevalences were found in the highveld compared to the lowveld (P < 0.001), for adult cattle than calves (P < 0.01), and in the wet over the dry season (P < 0.01). Faecal egg output peaked from October to March in both years of the study. Bulinus tropicus, Bulinus forskalii and Biomphalaria pfeifferi were recorded from the study sites. The main intermediate host for amphistomes was B. tropicus with a prevalence of infection of 8.5 %. However, amphistome cercariae were also recorded in Biom. pfeifferi and B. forskalii. Amphistome cercariae were recorded from both the highveld and lowveld areas with peak prevalence during the post-rainy season (March to May). Metacercariae were found on herbage from the fringes of the snail habitats between February and August, with most of the metacercariae concentrated on herbage 0–1 m from the edges of the habitats. Based on the epidemiological findings a control programme was devised. From this study, large burdens of immature flukes could be expected in cattle during the dry months. Since adult cattle would be resistant to the pathogenic effects of the migrating immature amphistomes the target for control would be young animals being exposed to the infection for the first time.Therefore, the first anthelmintic treatment can be administered in calves in mid June when maximum migration of immature amphistomes starting 3–4 weeks after infection in the early dry season would be expected. A second treatment could be given in late July or early August to remove potentially dangerous burdens of immature flukes acquired later in the dry season. Where resources permit, another strategy would be to treat against the mature flukes in March or April in order to reduce the number of eggs deposited on pastures and the opportunity for infection of the intermediate host snails. To reduce cercarial shedding by the intermediate host snails molluscicides can also be applied during the peak transmission periods (April/May and August/September). Post-Print to the original article available from: http://openjournals.net

Epidemiological studies of parasitic gastrointestinal nematodes, cestodes and coccidia infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe

Mon, 01 Jan 2007 00:00:00 GMT

Epidemiological studies of parasitic gastrointestinal nematodes, cestodes and coccidia infections in cattle in the highveld and lowveld communal grazing areas of Zimbabwe Pfukenyi, Davies Mubika; Mukaratirwa, Samson; Willingham, A.L.; Monrad, J. Between January 1999 and December 2000 faecal samples from 16 264 cattle at 12 dipping sites in the highveld and nine in the lowveld communal grazing areas of Zimbabwe were examined for gastrointestinal (GI) nematode and cestodes eggs, and coccidia oocysts. Strongyle larvae were identified following culture of pooled faecal samples collected at monthly intervals. The effects of region, age, sex and season on the prevalence of GI nematodes, cestodes and coccidia were determined. Faecal egg and oocyst counts showed an overall prevalence of GI nematodes of 43 %, coccidia 19.8 % and cestodes 4.8 %. A significantly higher prevalence of infection with GI nematodes, cestodes and coccidia was recorded in calves (P < 0.01) than in adults. Pregnant and lactating cows had significantly higher prevalences than bulls, oxen and non-lactating (dry cows) (P < 0.01). The general trend of eggs per gram (epg) of faeces and oocysts per gram (opg) of faeces was associated with the rainfall pattern in the two regions, with high epg and opg being recorded during the wet months. The most prevalent genera of GI nematodes were Cooperia, Haemonchus and Trichostrongylus in that order. Strongyloides papillosus was found exclusively in calves. Haemonchus was significantly more prevalent during the wet season than the dry season (P < 0.01). In contrast, Trichostrongylus was present in significantly (P < 0.01) higher numbers during the dry months than the wet months, while Cooperia and Oesophagostomum revealed no significant differences between the wet and dry season. These findings are discussed with reference to their relevance for strategic control of GI parasites in cattle in communal grazing areas of Zimbabwe. Post-Print Available from: http://openjournals.net

Horn Innervation in the Calf: An Immunohistochemical Study

Wed, 01 Mar 2000 00:00:00 GMT

Horn Innervation in the Calf: An Immunohistochemical Study Mudekurozwa, M.C; Purton, M; MacMillan, I; Boyd, J.C