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Animal and Poultry Science

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Browsing Animal and Poultry Science by Author "Ahmed, Mawahib Alhag Ali."

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    Gastrointestinal (nematode) infections in small ruminants : epidemiology, anthelmintic efficacy and the effect of wattle tannins.
    (2010) Ahmed, Mawahib Alhag Ali.; Nsahlai, Ignatius Verla.
    Nematode parasites have become the biggest problem for small ruminant production in South Africa due to their resistance to the commercial anthelmintics. Notable, wattle tannin has been used as an alternative strategy for control. However, the concentration and the frequencies can likely influence its effect on the parasites control. The objective of this study was to determine the degree of pasture infestation and nematode infection in sheep and goats, as well as investigate nematode resistance to the anthelmintics, and the potential of wattle tannin in nematode control. The first study dealt with the epidemiology of internal parasites. Eight Merino ewes and eight Nguni does averaged 7-18 months of age were observed for 1 year during the months of February 2008 to January 2009 at the University of KwaZulu-Natal Research Farm (Ukulinga). Egg count per gram (EPG) and coccidian oocysts per gram (OPG) were counted according to Mc Master Technique (Hansen & Perry, 1994) by magnifying parasitic eggs from monthly rectal faecal samples dissolved in saturated sodium chloride. Faecal samples also were cultured for 15 days to identify infective nematode larvae (L3) using Baermann technique. Herbage samples were collected monthly from four paddocks as well to count L3 on the pasture. Sheep live weight was also recorded monthly. Seasonal effects was significant (P<0.05) on the EPG, OPG, faecal culture L3 and pasture L3. A higher level of infection was observed in summer (wet) than in winter (dry season). Trichostrongylus spp larvae were the most prevalent larvae (26.5%) while Strongyloides, Haemonchus contortus, Nematodirus and Cooperia spp occurred in the faecal culture by percentage of 20.9%, 16%, 16% and 14.5%, respectively. For parasite resistance, Ivermectin 1% (IVM), Closantel 5% (CST) and a combination of Abamectin 0.08% and Praziquantel 1.5% (CPA) were evaluated. Twenty four sheep (12 females and 12 males) aged between 7-18 months were used for 21 days. Animals were naturally infested by gastro-intestinal parasites. EPG and faecal culture L3 were counted on day 0, 7, 14 and 21. Closantel was the most effective. Haemonchus spp. were least affected whilst Trichostrongylus spp. were the most affected by all drugs. In the third study, wattle tannins were evaluated as an alternative nematode control drug. Three experiments (Exp.) were conducted to determine the effect of tannin concentration (Exp.1 and 2) and frequency (Exp.3) on nematode parasites. In Exp.1, 0, 0.8, 1.6 and 2.4 g tannin/kg BW were drenched for three consecutive days per sheep (16 females and 8 males, aged 8-9 months) for 21 day. In Exp.2, 30 sheep (14 males and 16 females, aged 9-18 months) were randomly allocated into three tannin treatments (0, 0.8 and 1.6 g tannin/kg BW) and drenched for a day. In Exp.3, 26 sheep (11 males and 15 females aged 9-18 months) were divided into three groups of 9, 9, and 8 sheep each. These groups were drenched with 1.6 g tannins/kg BW/day; once, twice or thrice for the 3 groups respectively. For the three experiments, EPG and L3 larvae were counted in individual feacal samples. For all tannin treatments, EPG decreased (P<0.05) over time. Though the differences among tannin levels and frequencies varied (P<0.05) over time, EPG consistently decreased with increasing tannin level and frequency. Thus 1.6 and 2.4 g tannin /kg BW for 3 consecutive days had nearly similar effects on the EPG. The results of this study are rather inconclusive that weather conditions such as rainfall had a direct effect on internal parasites development. Nematode parasites at Ukulinga Research Farm were resistant to the commercial anthelmintics used. Drenching with 1.6g wattle tannin/kg BW over three successive days is enough to reduce EPG and reduce the degree of pasture contamination.
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    Integrated control of gastrointestinal nematodes of sheep using plant extracts. and bicontrol agents.
    (2013) Ahmed, Mawahib Alhag Ali.; Laing, Mark Delmege.; Nsahlai, Ignatius Verla.
    Infection of small ruminants by gastrointestinal nematodes (GIN) is a major health concern because they cause substantial economic losses, especially in the tropics and sub-tropics. For many years, control of GIN has been based upon use of anthelmintics. However, there is now a global challange because mutant GIN individuals can tolerate most of the widely used anthelmintics. Therefore, alternative control measures are needed. The objective of the study was to screen a number of plant species for their anthelmintic effects, and to evaluate selected strains of Bacillus thuringiensis (Berliner) and Clonostachys rosea (Schroers) for activity against sheep GIN. Subsequently, the combined treatments would test a dual control strategy for nematodes by using a combination of plant extracts with biocontrol agents. Ethanol extracts of 25 plant species were screened for their anthelmintic effects against Haemonchus contortus (Rudolphi 1803). Extracts of each plant were used in vitro at various concentrations (10, 20 and 30%) to treat 10 day faecal cultures. Five plants with high efficacies (Ananas comosus L. Merr., Aloe ferox Mill., Allium sativum Linn., Lespedeza cuneata Dum. Cours. and Warburgia salutaris Bertol.f. Chiov) were selected for further investigation, using ethanol, dichloromethane and water extracts at four concentrations (2.5, 5, 10 and 20%). Ethanol was the most effective solvent. Larval counts decreased as a result of increasing extract concentrations. An ethanolic extract of Lespedeza cuneata caused more than 70% mortality at all concentrations. In an in vivo study, the five plants A. comosus, A. ferox, A. sativum, L. cuneata and W. salutaris extracts were compared to a positive Control (Equimax®, a modern anthelmintic based on abamectin and praziquantel). Gender, eggs count (EPG₀) and initial body weights were used in assigning sheep (24 females and 24 males) to six groups. Each group was randomly assigned a treatment. Plant extracts were applied as an oral dose (100 mg kg⁻¹ BW), one dose per week per animal for 42 days (Phase 1). Subsequently, the same sheep were dosed for three consecutive days with the same treatments, keeping them in the same groups (Phase 2). Rectal faecal samples were taken for counting of eggs per gram of faeces (EPG) and L₃ larvae per gram (LPG) in faecal cultures. With application of plant extracts, the EPG count decreased with time (P<0.001), and the impact of the plant extracts increased (P<0.001) with time. Two extracts, from A. comosus and L. cuneata, were the most effective in Phase 1 (58% and 61% reduction of EPG, respectively,), and in Phase 2 (77% and 81% reduction of EPG, respectively). In a study on potential biocontrol agents, two strains of Bacillus thuringiensis (Bt) and one of Clonostachys rosea f. rosea (C. rosea), and compared with a diatomaceous earth (DE) product for their anthelmintic activity in sheep. Bacillus thuringiensis and C. rosea were fed to sheep at a rate of 1g kg⁻¹ BW, and DE was fed at 2% of sheep diet. The biocontrol treatments had no effect on EPG (P>0.05), but reduced GIN larvae per gram (LPG) (P<0.001) in faecal culture. Efficacy varied with time (P<0.001). By Day 7 Bt, C. rosea and DE had caused mortalities of GIN of 75.7, 86.9 and 60.6%, respectively. In addition, the efficacy of feeding 1g kg⁻¹ BW of C. rosea chlamydospores to sheep every day, every second day and every third day was tested. Daily feeding of fungal chlamydospores reduced LPG (a count of 12±1.67 GIN larvae) (P<0.001) more than feeding them the biocontrol agent every second day (39±0.77) or third day (58±1.77). By Day 12, feeding the biocontrol agent to sheep every day, every second day, or every third day caused mortality of GIN larvae of 90, 63 and 49%, respectively. Four dietary levels (treatments) of C. rosea (0.25g (F1), 0.5g (F2), 1g (F3) and control (C) of C. rosea product kg-1 BW) were tested. Treatments were each mixed with a complete diet and fed to sheep once daily for 10 weeks, according to body weights. Increased doses of the biocontrol agent reduced LPG (P<0.001), larval development (LD) (P<0.001), and increased efficacy (P<0.001). On Day 70, F1, F2, F3 and the Control controlled LD by 33.3, 72.3, 89.4 and 2.6%, respectively. Clonostachys rosea was effective in reducing third stage larvae (L₃) on pastures significantly (P<0.001) by Day 63 and Day 70. Ethanolic extracts of A. comosus, A. ferox, A. sativum, L. cuneata and W. salutaris all reduced egg production by GIN parasites of sheep. Feeding sheep cultured chlamydospores of a biocontrol fungus, Clonostachys rosea, reduced counts of nematode larvae in sheep; and 1g C. rosea chlamydospores kg⁻¹ BW daily was enough to reduce nematode infective larvae, therefore reducing the degree of pasture contamination. An initial trial showed that the combination of the two treatments of an A. comosus extract and C. rosea chlamydospores was more effective than either treatment on its own in controlling gastrointestinal nematodes in sheep. A long-term trial is being undertaken currently to confirm this finding.