Prevalence and risk factors of gastrointestinal parasitic infections in goats in low-input low-output farming systems in Zimbabwe

AbstractA longitudinal study was conducted in low-input low-output farming systems to determine the prevalence of gastrointestinal parasitic infections in different age groups, sex and associated risk factors in goats. A total of 580 indigenous goats were randomly selected in areas representing the five agro-ecological regions of Zimbabwe in the dry and wet seasons. Blood and faecal samples were collected from each animal and egg/oocyst per gram of faeces (epg/opg), larval culture, and packed cell volumes (PCV) were determined. Factors affecting parasitic infections were evaluated. Highest prevalence was determined for Eimeria oocysts (43%), strongyles (31%) and lower levels in trematodes and cestodes. Parasites identified were Haemonchus, Strongyloides and Oesophagostomum. Area, season, sex and age significantly influenced patterns of gastrointestinal infections (P<0.05). Cannonical correlations indicated that parasite species composition varied by area and impacts of risk factors also differed. Risk of infection was very high for goats sampled in Natural regions (NR) I, II, III (OR=6.6–8.2; P<0.05) as compared to those in NR IV and V. Highest helminths and Eimeria infections were observed in the wet vs. dry season (P<0.05). Young animals were more susceptible to parasitic infections (P<0.05). Prevalence was higher in males than females, with odds of infection for males being almost three times to that for females (P<0.0001). Knowledge concerning gastrointestinal helminth biology and epidemiological infection patterns caused by these parasites is essential in the development of appropriate control strategies and this has a potential to reduce production losses

Breeding for resistance to gastrointestinal nematodes - the potential in low-input/output small ruminant production systems

AbstractThe control of gastrointestinal nematodes (GIN) is mainly based on the use of drugs, grazing management, use of copper oxide wire particles and bioactive forages. Resistance to anthelmintic drugs in small ruminants is documented worldwide. Host genetic resistance to parasites, has been increasingly used as a complementary control strategy, along with the conventional intervention methods mentioned above. Genetic diversity in resistance to GIN has been well studied in experimental and commercial flocks in temperate climates and more developed economies. However, there are very few report outputs from the more extensive low-input/output smallholder systems in developing and emerging countries. Furthermore, results on quantitative trait loci (QTL) associated with nematode resistance from various studies have not always been consistent, mainly due to the different nematodes studied, different host breeds, ages, climates, natural infections versus artificial challenges, infection level at sampling periods, among others. The increasing use of genetic markers (Single Nucleotide Polymorphisms, SNPs) in GWAS or the use of whole genome sequence data and a plethora of analytic methods offer the potential to identify loci or regions associated nematode resistance. Genomic selection as a genome-wide level method overcomes the need to identify candidate genes. Benefits in genomic selection are now being realised in dairy cattle and sheep under commercial settings in the more advanced countries. However, despite the commercial benefits of using these tools, there are practical problems associated with incorporating the use of marker-assisted selection or genomic selection in low-input/output smallholder farming systems breeding schemes. Unlike anthelmintic resistance, there is no empirical evidence suggesting that nematodes will evolve rapidly in response to resistant hosts. The strategy of nematode control has evolved to a more practical manipulation of host-parasite equilibrium in grazing systems by implementation of various strategies, in which improvement of genetic resistance of small ruminant should be included. Therefore, selection for resistant hosts can be considered as one of the sustainable control strategy, although it will be most effective when used to complement other control strategies such as grazing management and improving efficiency of anthelmintics currently

A genome-wide association study on mechanisms underlying genetic resistance to gastrointestinal parasites in goats, Zimbabwe

Thesis (PhDAgric)--Stellenbosch University, 2017.ENGLISH ABSTRACT: Genome wide association studies (GWAS) have evolved into powerful tools for investigating the genetic association of complex traits, such as gastrointestinal parasite (GIN) resistance. Knowledge on genes associated with GIN resistance can provide information for use in breeding programs. The objective of the study was to identify markers associated with resistance in goats, through the following specific objectives: i) assessing the level of knowledge on GIN, management and control of GIN, ii) determining the prevalence and risk factors of GIN, iii) determining genetic diversity and population structure of goats in Zimbabwe and iv) investigating genomic loci associated with GIN resistance traits using a genome-wide association analyses (GWAS). Surveys were conducted in 135 households, using a pre-tested questionnaires in Chipinge (natural region (NR) I and II), Shurugwi (NR III), Binga and Tsholotsho (NR IV) and Matobo (NR V). GIN were ranked highest as the most common disease, with 57% of farmers not controlling or treating animals and 63% of farmers not having knowledge on the spread of GIN. A total of 580 blood and faecal samples were collected from goats from the same households, with additional sampling being conducted in the Research station flock. Highest prevalence was determined for Eimeria oocysts (43%) and Strongyles (31%). Area, season, sex and age significantly influenced patterns of GIN infections (P < 0.05). Prevalence was highest in goats from Chipinge and Binga, greater in wet than dry season and in males than females. High prevalences were observed for goats aged 1 and 6 years and the least for goats aged 3. Associated risk factors were also evaluated per area. A subset of the sampled animals (253) was genotyped using the Illumina Goat 50 K SNP beadchip. Population structure analyses were performed using ADMITXURE and PLINK. Five clusters were identified, with distinct populations of Binga and high levels of shared ancestry in goats from Tsholotsho and Matobo districts. Genetic parameters indicated high levels of genetic diversity based on observed (HE) and expected (HO), low linkage disequilibrium (r 2 = 0.03 - 0.18) and low FST (0.01 – 0.04). For genome-wide analyses, two approaches were used: i) single-SNP association using logarithm transformed faecal egg counts, ii) within-population association using case/control data. After quality control, 49 984 SNPs and 44 918 SNPs were available for genome-wide association analyses in GenAbel and PLINK respectively. The study confirmed that GIN resistance traits were heritable (0.27 - 0.56 i.e low - moderate). The analyses revealed significant multiple SNPs that were associated with Eimeria and Strongyles at the genome-wide level. Regions on chromosomes (chr) 4 (P = 2.66 x10-6 and P = 1.45 x10-5) for Eimeira and chr 29 (P = 9.93 x10-6) were found to be associated with GIN resistance, for the Eimeria and Strongyles traits. Genes annotated to the SNP positions were ORC5, DGKB and HRASLS5, respectively. The role of the genes have not been reported in previous studies or implicated in the involvement of biological pathways that have roles in eliciting responses towards GIN infections. Overally, the study demonstrates the utility of the Illumina Goat 50 K SNP, despite that the animals used in the study were not represented in the SNP discovery breeds. Knowledge of these genes and understanding the underlying mechanisms to GIN resistance can be used in the development of breeding programs and hence improve productivity.AFRIKAANSE OPSOMMING: Genoom wye assosiasie studies (GWAS) het ontwikkel in ‘n kragtige instrument vir die ondersoek van genetiese verwantskappe van komplekse eienskappe, soos gastro-parasiet weerstand. Kennis oor gene wat verband hou met gastro-parasiet weerstand kan inligting verskaf wat gebruik kan word in teeltprogramme. Die doel van hierdie studie was om merkers geassosieer met weerstand in bokke te identifiseer, deur die volgende spesifieke doelwitte: (i) die bepaling van die vlak van kennis oor gastro-parasiete onder kleinboere, hul bestuur en beheer van gastro-parasiete (ii) die bepaling van die voorkoms en risikofaktore van gastro-parasiete (iii) bepaling van genetiese diversiteit en populasisestruktuur van bokke in Zimbabwe (iv) die ondersoek van genomiese lokusse wat verwant is aan gastro-parasiet weerstand eienskappe met behulp van ‘n genoom wye assosiasie studie (GWAS). Opnames is in 135 huishoudings, met behulp van ‘n pre-toetse vraelyste in Chipinge (natuurlike gebied (NG) I en II), Shurugwi (NG III), Binga enTsholotsho (NG IV), en Matobo (NG V) distrikte, wat vyf landbou-ekologiese streke in Zimbabwe verteenwoordig. Gastro-parasiete was die hoogste geklas as die mees algemeenste siekte, met meerderheid van die boere (57%) wat nie beheer toepas of siek diere behandel nie en 63% van die boere wat geen kennis het oor die verspreiding van gastro-parasiet siektes nie. ‘n Totaal van 580 bloed en fekale monsters was versamel van bokke vanuit dieselfde huishoudings, met bykomede monsterversameling gedoen in die Navorsingstasie kudde. Hoogste voorkoms was Eimeria oösiste (43%) en Strongyles (31%). Gebied, seisoen, geslag en ouderdom het die patroon van gastro-parasiete infeksies beduidend beïnvloed (P < 0.05). Voorkoms was die hoogste in bokke vanaf Chipinge en Binga, asook hoër in die nat teenoor droë seisoen en hoër in bokramme teenoor bokooie. Hoë voorkoms is ook waargeneem vir bokke 1 en 6 jaar oud en die minste vir bokke 3 jaar oud. Geassosieerde risikofaktore is ook geëvalueer per area. ‘n Subset van die gemonsterde diere (253) was genotipeerd met behulp van die Illumina Bok 50 K SNP beadchip. Populasiestruktuur analise is uitgevoer met behulp van ADMITXURE en PLINK. Vyf klusters is geïdentifiseerd, elk met sy eie bevolkings van Binga en hoë vlakke van gedeelde afkoms in die bokke vanaf Tsholotsho en Matobo. Genetiese parameters is aanduided van hoë vlakke van genetiese diversiteit gebaseerd op die waargeneemde (HE) en verwagte (HO), lae koppeling onewewigtigheid (r 2 = 0.03 - 0.18) en lae FST (0.01 – 0.04). Vir genoomwye ontledings is twee benaderings gebruik: i) enkel-SNP assosiasie met behulp van logaritme veranderde fekale eiertellings ii) binne-populasie assosiasie met behulp van gevalle/kontrole data. Na gehalte beheer, 49 984 SNPs en 44918 SNPs was beskikbaar vir die genoomwye assosiasie analise in GenAbel en PLINK onderskeidelik. Die studie het bevestig dat gastro-parasiete weerstand eienskappe is oorerflik (0.27 - 0.56 d.w.s lae tot gemiddeld). Die analise het beduidende verskeie SNP’s openbaar wat verband hou met Eimeria en Strongyles by die genoomwye vlak. Streke op chromosome (chr) 4 (P = 2.66 x10-6 and P = 1.45 x10-5) vir Eimeira en chr 29 (P = 9.93 x10-6) is gevind wat verband hou met die gastro-parasiete weerstand, vir die Eimeria en Strongyles eienskappe. Gene geannoteerd naby hierdie SNP posisies was ORC5, DGKB en HRASLS5 onderskeidelik. Die rol van die gene is nog nie aangemeld in vorige studies of hul betrokkenheid by biologiese weë wat reaksie lok teenoor gastro-parasiete infeksie nie. In geheel, toon die studie die nut van Illumina Bok 50 K SNP, ten spyte daarvan dat die diere gebruik in die studie nie die diere verteenwoordig wat gebruik was in die SNP ontdekking rasse nie. Kennis van hierdie gene en die begrip van die onderliggende meganismes van gastro-parasiete weerstand kan gebruik word in die ontwikkeling van teelprogramme en sodoende produktiwiteit verbeter

Sustainable Utilization of Indigenous Goats in Southern Africa

Goats have a key role in ensuring food security and economic livelihood to smallholder farmers in rural areas. Women play a vital role in goat rearing, promoting economic autonomy within households. Indigenous goats dominate and are of high significance due to their adaptive traits that are relevant for climate change and low maintenance. However, lack of emphasis on farmer-centered technology development and proper breed characterization remains a hitch to sustainable utilization and breed development of indigenous goats. This can be over come through proper linkage between market and production, workable regional and national agricultural policies, community breeding programs, collaborative research work within the region, and consistent government support

PERFORMANCE OF MASHONA COWS REARED ON NATURAL RANGELANDS WITH NON-CONVENTIONAL PROTEIN SUPPLEMENTATION IN THE DRY SEASON, ZIMBABWE

Performance of animals in smallholder farming systems is hindered by feed availability and feed costs that make up 60-70% of total variable cost in a farming system. The use of non-conventional feedstuffs is an alternative which can be adopted to minimize feeding costs. The study was conducted to evaluate performance of animals fed with supplements formulated on-farm in comparison with a commercial prepared supplement. Thirty Mashona cows were grouped according to age and subjected to five treatments, given twice a week from the 1st of September until 31st December for three subsequent years. The five treatment diets, beef survival meal (BSM), urea treated maize stover (UTS), Leucaena leucocephala meal (LLM), mixed forage meal (MFM) and natural pastures (NP) were randomly assigned to cows in a complete randomised design (CRD). Average weight gains were determined. Performance in the first year was not significantly different across treatments. In the subsequent years, performance remained low in the NP. Average weight gains increased in the second and third years and was significantly different across treatments (P<0.05). Performance of animals supplemented with non-conventional feed was comparable to those offered commercial BFM; hence LLM and UTS can be used as alternative protein supplements especially in resource-constrained farming systems.

Degradability of amino acids in selected legume forages using the in situ nylon-bag technique

This study was conducted to determine the amino acid profiles and rumen degradability of amino acids of three cultivated forage legumes – velvet bean (Mucuna pruriens), cowpea (Vigna unguiculata) and silverleaf desmodium (Desmodium uncinatum) – using the in situ nylon-bag technique. Two Friesian cows fitted with 10-cm-diameter rumen cannulae on a complete dairy feed ration (19% crude-protein dairy meal and maize silage) were used. Silverleaf desmodium had significantly (p &lt; 0.05) higher concentration of amino acids compared with cowpea and velvet bean. Aspartic acid showed the highest (p &lt; 0.05) concentration in all legumes and cysteine showed the lowest concentration. Legume forage of cowpea showed the highest (p &lt; 0.05) level of degradability of amino acid followed by silverleaf desmodium and then velvet bean. Readily and slowly degradable components in all amino acids were highest (p &lt; 0.05) in cowpea followed by silverleaf desmodium and then velvet bean. Moreover, silverleaf and cowpea showed higher (p &lt; 0.05) levels of effective degradability of amino acids (at outflow rates p = 0.02, 0.04 and 0.06 h−1) than velvet bean. Total amino acid disappearance was the least in velvet bean, which suggests that it can be used to supply bypass protein to the duodenum of the ruminant animal.Keywords: amino acids, forage legumes, rumen degradabilit

Apparent digestibility and microbial protein yield of Desmodium uncinatum, Mucuna pruriens and Vigna unguiculata forage legumes in goats

This study examined the effects of adding forage legumes as protein supplements to poor-quality natural pasture (veld) hay offered to goats on microbial protein yield and nitrogen metabolism. Four indigenous Nguni-type goats were used in a 4 × 4 Latin cross-over design experiment. Goats were randomly allocated to four dietary treatments comprising commercial goat feed (GF), veld hay supplemented with cowpea (CW), velvetbean (VB) or silverleaf desmodium (SD). Microbial protein yields were determined using the purine derivatives technique and nitrogen retention was calculated from the digestible organic matter intake. Total nitrogen intake was significantly higher in the GF followed by CW, SD and VB, respectively. Microbial protein supply, calculated microbial true protein and digestible microbial true protein were affected (P &lt; 0.05) by legume supplementation. Animals on poor-quality forages had the most efficient microbial protein synthesis. However,  supplementation of hay failed to meet the maintenance requirements of animals as evidenced by negative nitrogen balances in VB and SD. The efficiency of utilisation of nitrogen in the supplements could have been limited by unavailable fermentable metabolisable energy in the diets.  Supplementation of poor-quality veld hay with legume forages could improve utilisation, especially in the dry season.Keywords: forage quality, goats, utilisatio

Effect of Moringa oleifera

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