Review ArticleAbstract
Poisonous plant is one of the causes of livestock health problems all over the world and brings significant economic loss. Therefore, a cross sectional study was concluded in and around Horo Buluk district North Horo Guduru Wolega Zone of Oromia Regional State, western Ethiopia from September to December 2017 with the objective of identifying poisonous plant and their toxic effect in the study area. In order to put the objective into practice, structured questionnaires were developed and 130 individuals (120 livestock owners and 10 animal health practitioners) were interview on voluntary basis. At the end of the survey, it was found that 102 (78.5%) of livestock owners and 10 (100%) of animal health practitioner complained the presence of plant poisoning on livestock’s in the study area. Similarly, 33 plants were identified as having poisoning effect on livestock, among which Trifolium Hybridium, snowdina polystarchia, Plantago Laceolata, Urtica doca solanium, guizotia scabra and had the highest botanical frequency. According to the result of survey, agricultural expansion, draught, soil erosion and overgrazing predispose the livestock’s to plant poisoning. In the same way, almost all of the livestock’s were managed by extensive type of production system which allows them to browse poisonous perennial herbs on identified. On the other hand, the livestock’s were poisoned by leaves and other parts of the identified poisonous plants through ingestion or contract. In conclusion, from the current study, high number of poisonous plant was obtained in the area. Hence, the livestock health in the area is at high risk of exposure to these toxic plants and therefore the government should intervene to create awareness among the community about the effects of these plants and for further photochemical and toxicological studies and possibly pharmacological activity.
Keywords: Botanical frequency; Ethiopia; livestock; Poisonous plants; Questionnaire
Introduction
Plants add a touch of color and fragrance to our daily lives. They
also inject an element of anger in our lives and they cannot move to
escape their predators. So, all plants have other means of protecting
themselves from the herbivores. Some plants have physical such as
thorns. But others contain some toxic. Chemical defenses of plants
against consumption by herbivores are determined by non-nutrient
compounds such as fiber, lignin, cellulose, toxicants or essential oils
and other volatile substances. Some volatile substances are overtly
toxic others are merely unpleasant [1].
Plant poisoning is due to either accidental ingestion of material
eaten along with grass or willful consumption of poisonous
plants when pasture is dry while most poisonous plants remain
green all the year round. It is also more likely to occur in animals
which have been moved from one part of country to another. New
importations are unfamiliar with the strange ingestion of their
fresh surrounding. Acclimatization in herbivores animals induces
a sense of discrimination between edible and non-edible parts [2].
Even though many of the medical substances produced by plants [3], some of them have been reported as toxic [4,5]. Plants may cause toxic effects or even death as a result of accidental exposure by skin contact/absorption, eye exposure and inhalation or accidental ingestion of the plant parts (seed, fruit, root, etc) while owner usually does not even suspect their toxic nature [6,7]. Plants affect animals in many ways although symptoms and lesions differ depending on the amount of the plant consumed. The common symptoms however include chronic illness debilitation, decreased weight gain, abortion, abdominal discomfort, salivation, congenital defects, photosensitization and sudden death can occur without the presentation of clinical signs [8].
Currently and rapidly diagnosing a plant poisoning is often
extremely difficult. In many cases initial clinical signs are nonspecific
(such as diarrhea) and post-mortem lesions may be absent.
However, diagnosis of plant poisoning of livestock depends on the
history, clinical syndrome observed, post-mortem lesions, evidence
that plants have been grazed, and remains of toxic plants in the
gastrointestinal tract. In addition, specialized veterinary toxicology
laboratories may provide testing for plant toxins and should be
consulted. Thus, the best way to support a diagnosis of a plant
poisoning is to confirm the presence of a toxic plant in the animal’s
environment, and to confirm that the plant has been ingested [9].
Awareness of poisonous plants growing in a certain geographical
region and their associated clinical signs are instrumental in making
a diagnosis and initiate treatment [10]. It is important to establish
an accurate diagnosis in order to provide adequate treatment to
affected animals, carefully and accurately assess the potential for
the transfer of toxins into edible products and prevent further
exposures. Most importantly, recognition of poisonous plants in
hay or forage may help prevent plant poisonings in animals [11].
In Ethiopia, to this date, most of the available information about
poisonous plants is case reports. Thus, it is virgin (neglected) area
for interested researchers to fill available gaps regarding paucity
of information on the effects of poisonous plants on livestock.
Therefore, the objective of this study is: To identify different
poisonous plants and their toxic effects on livestock in and around
the Oda Buluk District area.
Materials and Methods
Study Area
The study was conducted from September 2017 to December 2017 in and around Horo Buluk district, northern Horo Guduru Wolega Zone of Oromia regional state, western Ethiopia. The district is located at 322 km West of Addis Ababa. It is lies between 37005 ‘05’- 37007 ‘45’’East and 9033 ‘00’-‘’9035’25’’North longitude and on the altitude of 2503meter above sea level. The mean annual rain fall is 1264mm, the rain period ranges from April to October. It has a warm humid climate with mean minimum and average temperature of 15.70c (NMSA, 2003). The farming system at the area is crop livestock mixed type. The number of livestock population of the area was, cattle in head (61901), sheep (10112), goat (1100), horse (3795), mule (1054) and donkey (8668) poultry(30749) (CSA, 2008).
Study Population
The target study populations were voluntary animal owners and animal health practitioners. A total of 120 animal owners and 10 animal health practitioners were interviewed by employing close approaches to collect important data relevant to the study.
Study Design and Sampling Methods
A cross sectional study was used to interview voluntary animal owners and animal health practitioners. For this study, structured questionnaire was design to collect information related to plant poisoning on livestock in the study area. Questionnaire survey was carried out on the selected individuals by interviewing voluntary animal owners and animal health practitioners. Livestock owners and animal health professionals were randomly selected for the interview. The district was purposefully selected by taking into consideration of distance from the zone and occurrence of a variety of plant vegetation cover in the area different and plant poisoning.
Study Methodology
The study was conducted through questionnaire surveys designed for livestock owners and animal health professionals. A total of 130 individuals were interviewed from the district by applying face to face approach. The structured questionnaire was used to collect information related to toxic plants to livestock and its associated risk factors such as agricultural expansion, drought, over grazing and soil erosion. The plants were collected with their local name from surrounding forests and other sites where the plant is found with the interview individuals.
Data Management and Analysis
Suspected poisonous plants to livestock were collected in the area through structured questionnaire and according to the respective respondents the data were stored in the Microsoft Excel spread sheet 2010. Before the analysis of the coded data, it was filtered. Finally, it was analyzed and presented using tables. Lastly by applying descriptive statistics, frequencies and percentage were calculated.
Results
In this study, a total of 130 individuals were interviewed, of
which 120 individuals were livestock owners and 10 individuals
were animal health practitioners by employing structured
questionnaire. Out of interviewed interviewee, 102 (85%)
individuals complained the presence of poisonous plants in the
study area where as 18 (15%) individuals had no information
about the presence of these plants in the study area. Similarly, all
of interviewed animal health practitioners 10 (100%) informed the
presence of these toxic plants (Table 1). During the present study, a
total of 33 plants were identified which have poisonous effects on livestock by interviewed individuals. In all interviewed individual
extensive type of management is practiced.
Among these plants Trifolium hybridium (20.8%), Snowdina
polystarchia (12.5%), Plantago Laceolata (10%), Urtica doca
solanium (7.5%) Guizotia scabra (5.8%) were the most frequently
complained toxic plants (Table 2). According to the result of current
study, livestock’s were mainly poisoned through contact and/
or ingestion of leaves (51.1%) and other parts of the poisonous
plants (stem, seed and fruit) which account for 34.5%. On the
other hand, livestock’s were predisposed to these toxic plants due
to agricultural expansion (29.5%), drought (22.3%), soil erosion
(8.6%) and overgrazing (3.6%) (Table 1).
Table 1: Summary of number respondents on poisonous plants in the study area
Table 2: Summary of the identified poisonous plants according to their botanical and local (Afan Oromo) name, poisonous parts, susceptible species and harmful effects.
Discussion
The current study showed that photo poisoning is the cause
of ill health in livestock in the study area. Out of 130 interviewed
individuals (120 of livestock owners and 10 animal health
professionals), 85% of livestock owners and 100% animal health
professionals informed that plant poisoning is posing significant
livestock health problems in the area. According to information
collected from the respondents, the condition is provoked
by scarcity of forage supply due to different reasons such as
agricultural expansion, drought, soil erosion, over grazing which
force animals to browse perennial shrubs and bushes while most of
these perennial plants have been known to contain toxic secondary
metabolites and the result of this study was in agreement with
the study findings reported in the Sokoto state, Nigeria [12,13] by
sharing similar risk factors and also with research finding reported
from in the North Central America [14].
In this study, 33 plants having toxic effect to livestock
were identified. Of these, Trifolium hybridium (25), snowdina
polystarchia (15), Plantago Laceolata (12), Urtica doca solanium(9),
guizotia scabra(7) were the most frequently complained toxic
plants. The differences might be due to various plants growing in
different geographical areas that have different geographic and
climatic factors. These factors also contribute to the variations
in the chemical composition of different poisonous plants in
different areas. In the same manner, the variation might also be
due to differences in level of information about these plants in
the community from which the information was collected [15].
According to data obtained from different published literatures,
most of the currently identified poisonous plants have worldwide
importance. For instance, Medico sativa is phototoxic plant
containing photo estrogen which is responsible for the reproductive
disorders in addition to bloating and other effects to poisoned
animals in the study area. A similar harmful effect of this poisonous
plant was also reported in Colombia [16,17].
The current study revealed that, an increase in the degree of
livestock poisoning by these toxic plants is corrected with factors
such as drought which was agreed with the finding reported in USA
(NCR, 1972)
[18]. Similarly, the importance of Trifolium Spp, Ricinus
cumunus and acacia Spp as causes of livestock poisoning have
been published in the different literature (Munro, 2009). Pteridium
aquilinium (Bracken fern) is also widely distributed in many parts
of the world. In Ethiopia, its existence and importance as cause of
enzootic hematuria has been previously shown in different regions
[19] and it has also been reported elsewhere [20].
The results of current study also indicated that livestock
production in the study area was mostly extensive type with a
very low population of animals kept under intensive production
systems. Land used for extensive grazing cattle contain complex
mixes of native and invasive plants which may increase the risk of
exposure to toxic plants, many of which have not been identified
and characterized to avoid livestock exposure and this finding was
in agreement with study result reported by in Brazil [21].
Conclusion and Recommendations
In general, based on the results of present study, it is possible
to conclude that, plant poisoning was one of the livestock health
problems in the study area. Depending on the result of present
study, the following recommendations were forwarded:
a. Preventing livestock from grazing the pasture infested by
poisonous plants.
b. During drought season providing livestock with sufficient
feeds to avoid the exposure to plant poisoning while searching
for feeds.
c. Hay and other feed stuff should be carefully inspected for
contamination with potentially toxic weeds before feeding.
d. Livestock owners should be advised to remove the toxic
plants from the pasture land.
e. Awareness creation should be made among the
community on the practice of intensive livestock management
system to minimize exposure of plant poisoning on the field.
f. During early spring season, livestock owners should give
due attention to the area where their livestock graze because
many poisonous plants grow and appear on the grazing field in
this season.
g. It is recommended that detailed investigation should be
performed to know the epidemiology of the poisonings caused
by plants.
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