Distribution, utilization and management of the extra-limital common warthog (Phacochoerus africanus) in South Africa

Swanepoel, Monlee (2016-03)

Thesis (PhD)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: In South Africa, the recognition of wildlife as a natural resource has developed into a lucrative game farming industry where wildlife has value for tourism, recreational hunting and commercial hunting, including meat production and live sales. The modern game ranching industry is largely influenced by the demand of tourists and hunters for certain species and a great diversity of species, which has resulted in South Africa having the second highest rate of ungulate introductions globally. The common warthog (Phacochoerus africanus) was extra-limitally introduced to various game farms and reserves in the Eastern Cape, Northern Cape and the Free State provinces of South Africa for conservation and game farming purposes. Warthogs are not enclosed by the standard fencing used on agricultural lands and nature reserves, and have become free-roaming in the introduced habitats. The species currently inhabit both private and public lands on which major agricultural activities are practiced in South Africa and as a known agricultural pest, have become a managerial problem in traditional agricultural settings. The meat from hunted warthog carcasses is still relatively under-utilized by hunters and/or the commercial sector likely from a lack of information regarding the safety and preparation of the meat. The study found that introduced warthogs are simultaneously considered and managed as an agricultural pest and game animal by agricultural producers. This conflicting approach to management results in unethical and unsustainable control practices with undesirable outcomes for both farmers and warthogs. Since the majority of agricultural producers indicated that they would be more likely to utilize the meat if presented with information on its nutritional profile, the study proposed the production and utilization of warthog meat as fresh game meat or processed game meat products as a strategy to purposefully manage introduced warthog populations. There is a general concern that introduced warthogs could be responsible for introducing and transmitting diseases to animals and humans, and the consumption of warthog meat could cause diseases or parasitic infections in humans. The study found the first record of the tick Rhipicephalus gertrudae on warthogs in South Africa to date, while the low abundance of R. simus was attributed to the fact that the study area largely fell outside the ticks’ preferred distribution range. Overall, the parasite species richness in the host population was low. These results may suggest that introduced warthogs can alter the distribution of parasites, and/or act as host to parasites not previously associated with warthogs. However, although warthogs are able to carry and transmit diseases to animals and humans, there is a lack of documented cases of this occurring in southern Africa outside of disease-controlled areas. In addition, no warthogs culled during this study showed obvious symptoms of diseases or carriers of parasites potentially harmful for human consumption, albeit this was not explicitly investigated in this study. The yields and meat quality characteristics of warthogs, and the use of warthog meat in processed products as determined in this study provides evidence that the species can be considered and utilized as a game animal for formal meat production. The overall carcass yields of warthogs were favourable and comparable to those of other wild ungulates, indicating production of warthog meat is economically feasible. Considering the effect of intrinsic factors such as sex and age, age appeared to have a more pronounced effect on the quality characteristics of warthog meat, while adult male warthogs had heavier body weights and higher yields compared to females. The study concluded that warthog meat should be marketed and labelled as whole muscle cuts considering the differences in quality characteristics among skeletal muscles. However, differences between sex, age and among muscles are considered negligible in terms of its nutrition and healthiness as the raw and cooked meat meat is high in protein (~ 20%) and low in fat (~ 2%) with a favourable polyunsaturated to saturated fatty acids ratio (PUFA:SFA) of < 0.45 and omega 6 to omega ratio 3 (ω6:ω3) ratio < 4, which is the recommended ratio for the human diet. However, the Longissimus lumborum (LL) muscle from warthogs culled on agricultural lands had a ω6:ω3 ratio > 4 compared to warthogs culled on a game reserve, while warthogs culled on the game reserve had higher levels of arachidonic acid. These differences were attributed to the differences in the regional and seasonal diet of warthogs. The sensory profile of warthog meat was dominated by pork aroma and flavour and tenderness, and it was proposed that total moisture content is an important factor influencing the sensory profile of warthog meat considering the overall low total fat. The meat was not described as being gamey, which raises the question of whether gamey attributes should be described as ‘associated with game meat’, and its aptness to distinguish among meat from different species. The study found the undesirable aroma and flavour described as “sour/sweaty” was not found only in adult males and was scored higher for juvenile warthogs of both sexes. The use of game meat in processed products could extend the value chain of game meat production, and the study found that warthog meat can be converted to healthy processed products without compromising the sensory attributes associated with the product, while providing further evidence that processes such as curing and smoking is able to reduce or ‘mask’ undesirable flavours. Neither sex nor age ultimately influenced the sensory profile of warthog back bacon produced from the Longissimus thoracis et lumborum muscle, which was overall high in total protein (~29%) and low in fat (< 2%) with a favourable fatty acid (FA) profile. The use of warthog meat in a ready-to-eat product known as cabanossi found that warthog and pork cabanossi had similar total protein (26.3% and 24.2%, respectively) contents, while the warthog cabanossi was lower in total fat content (6.9% and 13.7%, respectively), which did not affect consumer preference. Despite the encouraging results found in this study regarding the quality and properties of warthog meat, there are still many research questions regarding the distribution, impacts, utilization and management of warthog populations in South Africa. The study in its entirety provides baseline information pertaining to and influencing warthog yields and meat quality characteristics, and concludes that warthogs can be utilized as a game animal for meat production and utilization, with the benefit of producing an overall lean meat with desirable properties for processing.

AFRIKAANSE OPSOMMING: Die erkenning van wild as n natuurlike hulpbron het in Suid Afrika ontwikkel as ‘n aanloklike wildindustrie wat vleisproduksie en lewende verkope insluit. Die moderne wildboerdery word grootliks beinvloed deur die aanvraag van toerisme sowel as die jag van spesifieke spesies, asook ‘n verskeidenhied van ander spesies, wat daartoe gelei het dat Suid Afrika die tweede hoogste voorkoms van die vestiging van hoefdiere in die wereld het. Die algemene vlakvark (Phacochoerus africanus) is op klein skaal binne die landsgrense op verskeie wildreservate in die Oos Kaap, Noord Kaap en die Vrystaat gevestig vir wildbewarings- en wildboerderydoeleindes. Vlakvarke word nie binne gehou deur die standaard heinings wat op landbougrond en wildsreservate gebruik word nie, en beweeg vryelik rond in die gebiede waar hulle ingebring is. Die spesie kom tans algemeen op beide openbare en private grond waarop landbou bedrywighede plaasvind, voor, en het as ‘n algemene probleemdier in ‘n bestuursprobleem vir die boere en eienaars ontaard. Die vleis van die die vlakvark wat gejag word is tans nog relatief onbenut deur sowel die jagter as die sakesektor, waarskynlik a.g.v. ‘n gebrek van inligting aangaande die veiligheid en voorbereiding van die vleis. Hierdie studie het gevind dat vlakvarke as probleemdier sowel as wildspesie deur die landbouers beskou word. Hierdie konflikterende beskouing het uitgeloop op onetiese en onvolhoubare beheermaatreels wat tot onbevredeginde resultate vir beide die boere en die vlakvarke gelei het. Aangesien die meerderheid landbouers aangedui het dat hulle heel waarskynlik die vleis sou gebruik as hulle ingelig kon word oor die voedingswaarde daarvan, stel hierdie studie die produksie en benutting van vlakvarkvleis as vars en geprosesseerde wildsprodukte voor, as ‘n strategie om daardeur doelbewus die vlakvark populasies te probeer beheer. Daar bestaan ‘n algemene bekommernis dat vlakvarke verantwoordelik kan wees vir die bekendstelling en oordrag van siektes na die mens en ander diere en dat die verbruik van die vleis parasitiese infeksies en ander siektes in die mens kan veroorsaak. Die studie bied die eerste dokumentering van die bosluis, Rhipicephalus gertrudae wat tot op datum op vlakvarke in Suid Afrika gevind is, terwyl die lae infestasie van R simus daaraan toegeskryf kan word dat die studiearea grotendeels buite die bosluis se verkose verspreidingsarea val. Oor die algemeen was die infestasie van ekto-parasiete op die gasheerpopulasie laag. Hierdie bevindings kan daarop dui dat die vlakvarke die verspreiding van parasiete kan verander en/of as gasheer vir parasiete wat voorheen nie met vlakvarke geassosieer is nie, optree. Hoewel vlakvarke daartoe instaat is om siektes te dra en oor te dra, is daar ‘n gebrek aan gedokumenteerde gevalle van die aard in Suid Afrika. Geeneen van die vlakvarke wat vir hierdie studie gebruik is, het enige tekens van ooglopende siektes gehad of dat hulle draers van parasiete is, wat potensiëel gevaarlik vir menslike gebruik is nie. Hierdie aspek is egter nie eksplisiet in die studie ondersoek nie. Die gebruik en kwaliteit van vlakvarkvleis in geprosesseerde produkte soos vasgestel in hierdie studie voorsien bewyse dat die spesie beskou en benut kan word as ‘n jagdier vir formele vleisproduksie. Die algemene uitslag persentasie van vlakvarke was gunstig en vergelykbaar met die van ander hoefdiere wat daarop dui dat die produksie van vlakvarkvleis ekonomies haalbaar is. As die intrinsieke faktore soos geslag en ouderdom in ag geneem word, het ouderdom ‘n duidelike effek op die kwaliteit van vlakvarkvleis, terwyl volwasse manlike vlakvarke swaarder geweeg en ‘n hoër uitslag persentasie as vroulike diere gehad het. Die studie het ook tot die gevolgtrekking gekom dat vlakvarkvleis gemerk en bemark behoort te word as heel spiersnitte, met inageneming van die verskille in die kwaliteit van die verskillende skeletspiere. Die verskille tussen ouderdom, geslag en tussen spiere word as onbeduidend in terme van die voedingswaarde en gesondheidsvoordele beskou, aangsien die rou en gaar vleis hoog in totale proteien- (~ 20%) en laag in totale vet-inhoud (~ 2%) is met ‘n gunstige poliversadigde tot versadige vetsuur verhouding (PUFA:SFA) van < 0.45 en omega 6 tot omega 3 verhouding (ω6:ω3) wat die aanbevole verhoudings vir die menslike dieet is. Die LL spiere van die die vlakvark wat op landbougrond gejag is het egter ‘n verhouding van ω6:ω3 > 4 gehad teenoor die wat op ‘n wildreservaat gejag is, terwyl vlakvarke wat op die jagreservaat gejag is, hoër vlakke van arachidoniese suur gehad het. Hierdie verskille is toegeskryf aan die verskille tussen die streeks- en seisoenale dieet van die vlakvarke. Die sensoriese profiel van vlakvarkvleis word gedomineer deur ‘n varkvleis-aroma en -smaak, en sagtheid. Die totale voginhoud is ‘n belangrike bepalende faktor vir die sensoriese profiel van vlakvarkvleis as die algemene lae vetinhoud in ag geneem word. Die vleis was nie beskryf as tipies wild nie, wat die vraag laat onstaan of wildseienskappe daaraan toegedig of toepaslik gebruik moet word om tussen die vleis van verskillende spesies te onderskei. Die studie het gevind dat die ongewenste aroma en geur wat as “suur/sweterig” beskryf word, nie net in volwasse manlike diere voorgekom het nie en ‘n hoër telling is aangeteken vir jong vlakvarke van beide geslagte. Die gebruik van wildsvleis in geprosseseerde produkte kan die waardeketting van wildsvleisproduksie verleng. Die studie het bevind dat vlakvarkvleis tot gesonde geprosseseerde produkte verwerk kan word, sonder om die sensoriese eienskappe wat met die produk geassosieer word, in te boet. Verder word bewys dat prosesse soos die pekel en rook van die vleis die ongewensde geure kan verminder of verbloem. Nie die geslag of ouderdom het die sensoriese profiel van die vlakvarkrugspek wat van die Longissimus thoracis et lumborum spier gemaak is, beinvloed nie. Dit was oor die algemeen hoog in totale proteiene (~29%) en laag in vet (< 2% )met ‘n gunstige vetsuur (FA) profiel. Met die gebruik van vlakvarkvleis in ‘n gereed-om-te-eet produk bekend as cabanossi is bevind dat vlakvark- en varkcabanossi ooreenstemmende totale proteien (26.3% en 24.2%, respectively) inhoud gehad het, terwyl vlakvarkcabanossi laer in vetinhoud (6.9% en 13.7%, onderskeidelik) was, wat nie verbruikersvoorkeure beinvloed het nie. Ten spyte van die bemoedigende resultate wat hierdie studie aangaande die kwaliteit en eienskappe van vlakvarkvleis gevind het, is daar steeds vele navorsingsvrae oor die verspreiding, impak, gebruik en bestuur van die vlakvarkpopulasies in Suid Afrika. Die studie voorsien in sy geheel basiese inligting oor die faktore wat vlakvarkprodukte en -kwaliteit beinvloed en kom tot die gevolgtrekking dat vlakvarke as jagspesie vir vleisproduksie en -gebruik benut kan word, met die voordeel van ‘n laevet vleis wat oor positiewe eienskappe vir prosessering beskik.

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