By Jessica Matchett, Animal and Poultry Science, University of KwaZulu-Natal
A review of the use of plants with ethno-veterinary medical properties has been submitted to SAPPO for the benefit of its members. The review details many such plants that are indigenous to South Africa, and those from other regions that exhibit effects of interest to the pig industry. This short article gives a brief glimpse into the research described in the review article, which is available at www.sapork.com. The plants are mentioned in this article by their common names, but their scientific names can be found in the review.In this era of advancing doom and gloom about global recession and global warming, there is an increasing drive for all sectors to “go green”. As agriculturalists, our main worry is that we will go green and, as a result of lowered productivity, fail to see the next generation because we have all succumbed to starvation! So, is there a way to have your (green) cake and eat? I believe so…
You may be wondering how this green effect can play a role in the pork production sector. One of the many voices squealing to be heard above the rest is that group which lobbies against the use of antibiotic growth promoters in intensive agricultural production systems, with our pork industry being one of the so-called culprits. They claim, whether accurately or not, that the inclusion of sub-clinical doses of anti-microbials in feed undermines the effects of such drugs, and ultimately creates strains of super-bugs, which are resistant to treatment and hence are a major threat to human health.
There is still much research to be done in the field of ethno-botany with regard to its impact on the veterinary sector, particularly in South Africa. And more specifically, there are large gaps in the research pertaining to pigs. However, if one applies a little lateral thinking to the research which has already been done on the effects of such plants on human health, as well as on various animal species in other regions, one can clearly see that the potential for antibiotic growth promotants to be replaced with “green” alternatives is large.
The use of antibiotics as growth promoters in pig production systems is controversial, and growing to be more of a public concern all the time. Consumers are wary of products containing “unnatural” compounds, and tending increasingly towards “organic” products. The primary impetus behind the search for “alternatives” to antibiotic growth promoters is that the utilisation of antibiotics in animals destined for the human food sector allegedly allows for the survival of, and selection for, antibiotic-resistant micro-organisms. The public health sector has expressed concerns that these resistant bacteria may spread from livestock via the food products to humans, and result in increased incidences of human infection. However, the actual risk of antibiotic resistance being transmitted from food animals to humans is small, and is as yet unquantified, especially in the light of the small dosages of the drugs used for growth promotant purposes.
As a result of these fears, the European Union has banned dietary inclusions of antibiotic growth promoting substances in the production of livestock, and this has led to an emerging field of research: The use of predominantly plant-based alternatives. As yet, such wholesale prohibition of antibiotics has not been incorporated into South Africa’s legislature, but it would be prudent for livestock producers to pay attention to this issue, and to prepare for its impact on their production practices. The most obviously affected by such laws would be those involved in intensive production systems such as feedlots, layer and broiler chicken operations, and more importantly, pigs. Not much research has been conducted on indigenous South African ethno-veterinary plants, particularly with regard to their use in the pork production sector. Nevertheless, because humans and pigs share a similar physiology, my review has revealed several avenues of interest, both within the ethno-medical and ethno-veterinary fields, that might be of benefit to the pig industry. Established remedies and plants of potential viability are presented, with emphasis at three levels: A South African, an African, and a global level.
Some plants traditionally used in South Africa for the treatment of wounds and retained placenta in livestock have been screened for anti-bacterial and anti-inflammatory activity. The highest level of anti-bacterial activity was exhibited by large Devil’s thorn, kiaat or bloodwood, castor bean and pinnate false threadleaf. Extracts of veldt grape and Jatropha zeyheri showed high anti-inflammatory activity while pinnate false threadleaf displayed selective anti-inflammatory properties. These results suggest that many of the traditional medicinal plants used to treat these two conditions in livestock exhibit efficacy in counteracting infection and alleviating pain. Another study tested the anti-inflammatory activity of five plant species of which African potato and willow herb both acted anti-biotically. The most promising result of all the plant species was from willow herb, which demonstrated anti-bacterial, anti-inflammatory and anti-oxidant activity. There is pre-existing knowledge of the anti-microbial (anti-bacterial and anti-fungal) activities of the indigenous South African wild plum, demonstrating that this plant holds potential for further investigation.
Some of the plants that display anti-inflammatory properties are Kukumakranka, Blue squill/blue hyacinth and the indigenous South African pineapple lily plant species, which is used traditionally for this purpose. Eleven other plant species displayed high anti-inflammatory activity, suggesting their potential use in the ethno-veterinary field. Jessop bulbs showed good anti-bacterial activity against gram-positive bacteria, whilst cultivated garlic and wild garlic had the highest anti-fungal efficacy against the Candida albicans fungus. Myrtle-leaf milkwood leaf extracts, pepper bark tree bark and leaves, and cultivated liquorice rhizome extracts also proved to be effective against the fungus. These five plants thus have anti-fungal properties which could be investigated for similar action against fungal species known to pose a problem to pig producers.
Research emphasis has shifted to the search for effective natural anti-inflammatory alternatives without toxic side effects. Two successful plants that have such properties are the pineapple lily species and bushwillow. The main parts of plants predominantly employed in the traditional healing sector are the storage organs, namely bark, bulbs, tubers and rhizomes, which are characterised by high quantities of storage proteins and lectins.
Plants have also been researched in other regions of Africa. Extracts from the roots of coffee senna have proven to be inhibitory against bacteria, three plants (cheeseweed mallow, Cape chamomile and asparagus) are used in Lesotho to treat inflammatory conditions and bacterial infections, and red spike-thorn is a widely used and traditionally important anti-bacterial medicinal plant in East Africa. An indigenous Central African plants, Vernonia amygdalina (bitter leaf), is used in Western Uganda typically for anti-biotic, anti-bacterial and fungal infections, and for general pains. This suggests the plant possesses both analgesic as well as anti-microbial properties. Some Vernonia species are found in South Africa, such as V. glabra and V. oligocephala. African cabbage (cat’s whiskers) roots, leaves and flowers are boiled or cooked as food, and used to treat colic pains. Again, this suggests the potential of this plant to be utilised for further research into analgesic ethno-medicines.
In other global regions, several studies have been conducted on the use of both ethno-medical and ethno-veterinary properties of plants. Plants found to have some ethno-veterinary action were aloe vera, bamboo, turmeric, wild coffee, cashew, guava, neem, papaya, and coconut. Indigenous South African plants of similar species or the same family could perhaps in a future project be investigated for similar activity.
The inhibitory effects of tannins, extracted from four forage legumes (greater bird’s-foot-trefoil, bird’s-foot-trefoil, Sulla and sainfoin) have been tested against deer lungworm and deer gastrointestinal nematodes. Sainfoin tannins had the highest level of inhibitory activity but the others also showed potential. These results suggest significant potential for tannins to be utilised as anthelmintics. Although this research was conducted on ruminants, such results provide a motivation for similar research to be conducted in monogastrics. Many indigenous South African plants contain condensed tannins and could be investigated for specific anthelmintic effects in pigs.
An ethno-veterinary medical exploratory study, carried out in Trinidad and Tobago, examined backyard remedies used for pigs and chickens. Four remedies are of interest, namely male papaya, which is used to de-worm pigs by dietary administration; coffee grounds, which are used for treatment of scours in pigs; worm grass, and cotton bush, both of which are utilised as anthelmintics. Common tobacco leaves also demonstrated anthelmintic properties. Extracts of this plant either paralysed or killed Barber’s pole worms (red stomach worms or wire worms) in vitro. Although the level of efficacy is below that of standard anthelmintic agents such as Levamisole, the study demonstrated that there is justification behind the use of tobacco as an anthelmintic.
The dietary inclusion of potato protein was shown to result in improved average daily gain and gain: Feed ratios in growing pigs. The potato protein effectively reduced microbial populations in the caecum, colon and rectum, as well as in faeces. The results of this study demonstrate the potential for potato to be included in pig diets as an alternative to antibiotic growth promoters, both because of increasing performance parameters and because of its anti-microbial activity.
Until such time as South Africa enacts prohibitive legislation against antibiotic growth promoters it is unlikely that commercial pig producers would switch to herbal alternatives, unless there is a significant economic or production benefit. My review has uncovered a range of potentially useful plants with suitable properties that may be helpful when the time comes. The development of such plant products would have a large spin-off effect for the rural and peri-urban livestock sector in South Africa. For subsistence and small scale farmers, it would make economic and infrastructural sense to be able to utilise local flora in the place of antibiotic growth promoters, and for commercial producers it is reassuring to know that there are some locally grown medicinal plants that could take the place of these growth promoters if and when they are no longer allowed in this country.