Livestock Research for Rural Development 32 (10) 2020 LRRD Search LRRD Misssion Guide for preparation of papers LRRD Newsletter

Citation of this paper

Effects of Prosopis juliflora pod and leaf meal on physical characteristics of teeth and bones of goats in Kitui County, Kenya

S K Mutavi

School of Agriculture and Veterinary Sciences, South Eastern Kenya University (SEKU), PO BOX 170 - 90200, Kitui, Kenya.


Livestock farmers in Baringo and Kitui counties in Kenya have complained that their goats lose their teeth with time when feeding on Prosopis juliflora pods and leaves. On this basis two studies were done: (i) to establish the extent of this complaint by a survey in Kwa Vonza ward in Kitui county; and (ii) determine the effects of the Prosopis browse on the physical characteristics of the teeth and bones in an experiment, set up in South Eastern Kenya University (SEKU).

The laboratory study revealed that Prosopis browse caused the teeth and bones taken from slaughtered goats to crack or break into small pieces when soaked in aqueous suspensions of the meal from Prosopis pods and leaves and that the effects were worse for the pods than the leaves. The farmer survey revealed that 79% of the respondents indicated that Prosopis plant had negative effects in mature goats, especially loss of teeth and resultant loss of body condition, which impacted negatively on the returns to the farmers. The respondents noted that Prosopis juliflora was a real threat to livestock production in the pasturelands and that alternative uses should be explored like generation of biofuels.

Keywords: adaptation, biofuel, livelihood, resilience


Arid and Semi-arid lands (ASALs), accounting for more than 80% of the Kenyan land mass, provide a key foundation for indigenous livestock production and sustainability of economic livelihoods of local communities. Cattle, goats, sheep and camels are the common livestock kept to extensively forage on the natural pastures in these ASALs. However, due declining land size and poor rain patterns, the small scale livestock farmers are constantly faced with the problem of feed scarcity. This is attributed to several factors: inadequate rains in the growing seasons; low quality and quantity of the pastures; lack of conservation of excess feedstuffs and poor feeds utilization methods, like continuous communal grazing of pastures among others.

This feed scarcity in the ASALs has been of big concern to many stakeholders especially researchers, agricultural extension officers, public administrators (chiefs and county commissioners) and the livestock farmers themselves. The researchers have been doing research on pastures and feed utilization technologies with aim of developing better pastures and ways to utilize the pastures with minimal wastage of feedstuffs. The extension officers have been educating and disseminating the coping innovations and technologies on pastures and feed utilization to the livestock farmers to adopt. The livestock farmers, on varied degree, have been embracing the adaptive innovations and interventions in order to alleviate the problem of feed scarcity. These include: planting quality grasses and legumes to increase feed supply; harvesting of excess forage for conservation in the haybarn; chopping of feedstuff to reduce wastage during feeding and making hay and silage among other coping strategies. Some of the introduced grasses include Chloris gayana (Rhodes grass), Pennisetum purpureum (Napier grass) andBrachiaria brizantha (Mulato II) while the legumes include Leuceana leucocephala, Dolichos Lab lab, Lucerne and Calliandra species. In addition, efforts to address the feed scarcity, government administrators would encourage farmers to plant trees and grasses that have not been adequately researched on, like Prosopis juliflora (Weber, 2003).

For example, in Baringo County, P. juliflora, (native in Latin America – Peru, Chile and Uruguay), was introduced to rehabilitate degraded mines in Mombasa and pasturelands in the ASALs in the former Rift Valley in Kenya (Shitanda et al 2013). P. juliflora is also known by synonyms P.juliflora var. juliflora (Sw.) or Acacia juliflora among other names across the world. It is commonly known as Prosopis, Mathenge in Kenya and ironwood eterai among the Turkana community in Kenya.

Weber(2003) noted that P. juliflora is a deep-rooted tree that utilizes the sub-surface waters in most sandy and saline soils in areas with 300 – 1900m altitude. P. juliflora has promising potential as a fodder for goats, restoration of degraded forests (Shitanda et al 2013) and supply of gum Arabic, fuel, firewood, timber and nectar among other benefits (Maundu and Tegnas, 2005). It was against these benefits, for example, that P. juliflora was introduced in Mombasa in 1970s for rehabilitation of quarries in Bamburi and advocated for growing especially as a fodder in Baringo County (MOA, 2005). The livestock farmers, then, planted the leafy thorny legume in their fields to provide feeds to the goats in 1990s as no cognizance of its invasive trait or side effects had been noticed. However, in Baringo, it became invasive and became to be popularly be known as ‘Mathenge’ shrub. In addition, it further spread to Samburu, Wajir, Garissa, Tana River and Kitui Counties among other counties in Kenya. The goats among other livestock, liked browsing on the leaves and the mature pods of theP. juliflora. With time, due to the fast and wide spread of the P. juliflora legume, the livestock farmers thought that they had a lasting solution to feed scarcity. However, the livestock farmers observed that the plant became a nuisance due to its invasive nature and creation of thick bushlands that spread easily especially along the riverine ecosystems. In addition, later on, in the early 2000s and 2010s, the livestock farmers in Baringo County started noticing that their goats were constantly in poor body condition regardless of the fact that the goats spent many hours browsing in the pastureland on their favourite P. juliflora. Out of curiosity, some farmers in Baringo County examined the affected mature goats and noticed that these goats had broken and worn out teeth and could not browse with ease (Daily Nation, 2005). It is against this background that the researcher was motivated to carry out this research to analysize the pH of the leaf and pod extract meal and its effects on the teeth and bone of livestock and provide insights on the correlation to the destruction of the dentition and bones of the goats in ASALs in Kenya.

Methods and materials

This study was conducted in South Eastern Kenya University (SEKU) in Kitui County for a period of four (4) weeks in September – October 2019. Kitui County lies at latitude 0010′ and 300 south and longitude 37050′E and 390 0E with a semi-arid climate and a population of over 1 million people (Population census, 2019). In Kitui County, livestock production is a major activity for livelihood sustainability of the households. However, feed quality and quantity is a major challenge and some browse plants, like P. juliflora have been introduced to alleviate feed scarcity. In the recent past, some livestock had reduced performance, body condition and loss of teeth which needed evaluation. It is on this basis that this study was initiated; the research materials included the P. juliflora leaves and pods, which were collected from the Mikuyuni and Mwitasyano riverine ecosystems in Kwa Vonza / Yatta ward in Kitui Rural Sub-county in Kitui County and fresh bones and teeth from the carcass meat of goats slaughtered at SEKU. These leaves and pods were used in simple experimental designs in Agriculture wet lab in SEKU to evaluate the effects of the respective paste chemistry on the physical characteristics of teeth and bone of goats. In addition, a survey was done among the local small scale livestock farmers on their perceptions on the impacts of the P. juliflora on the teeth and performance of their goats in their farms.

Experiment design

Substantial amounts of P. juliflora leaves and pods were separately dried in the open, crushed in a crucible using mortar, then distilled water added to form thick pastes and their pH determined using a pH meter. In order to reduce experimental errors, the experiments involving each kind of paste were replicated three (3) times. The leaf and pods pastes were each divided into six (6) equal portions and each portions placed in a glass beaker. The beakers were grouped into two for each kind of paste: in each of the first set of beakers, two (2) teeth were placed and immersed in the leaf and pods pastes while in the second set, two (2) short rib bones of the goats were placed in each beaker and immersed in the thick leaf and pods paste respectively. For control purposes, two (2) teeth and two (2) short rib bones were immersed in equivalent amount of distilled water respectively. Then, all beakers were left undisturbed for two (2) weeks and comparisons made on visual observations on physical appearance, texture and strength of the teeth and the bones and conclusions drawn.

Survey design

The survey design involved interviewing ninety (90) respondents using closed questionnaires, who were purposively selected in the sample areas. The respondents were selected on criterion that the respondents had goats that grazes along the riverine ecosystems in Kwa vonza ward, Kitui Rural sub-county.

Results and discussion


The results were drawn from the experiments carried out in the agriculture lab in SEKU and responses from the survey carried out in the Kwa Vonza ward, Kitui Rural in Kitui County

The study revealed that the aqueous suspensions of P. juliflora foliage were acidic (Table 1). The pod meal was very acidic compared to the leaf meal. his acidity is suspected to have effects on the physical characteristics, like texture and compactness / flexibility of the teeth and bones of the browsing goats.

Table 1. pH of the foliage paste






Leaf meal paste

4.5 – 5.5

Slightly acidic

Pod meal paste

2.5 – 3.5

Very acidic

The acidic foliage had varied effects on the physical characteristics of teeth and bones of the goats within the period of study (Table 2). The effects were greatest on the teeth and bones immersed in the pod meal paste. The rib bones immersed in pod meal paste softened and became flexible while those immersed in leaf meal paste remained slightly compact with minimal extent of flexibility. The teeth immersed in pod meal paste were easily removed from the jaws and easily broken into pieces when a small force was applied while those immersed in the leaf meal paste were slightly removed from the jaw bones and not easily broken when a small force was applied. In the control experiments, no observable changes were made on both the teeth and the bones once the flexibility and breakage were tested by applying a small force on teeth and the bones

Table 2. Analysis of effects of Prosopis juliflora extract on bone and teeth of goats


Observable effects on the bones and teeth

Rank of
the effect


a. Bones remained compact / hard


b. Teeth remained intact on jaws and compact


Pod extract

a. Bones softened and become flexible


b. Teeth easily removed from the jaws and broken


Leaf extract

a. Bones still remained compact / hard


b. Teeth slightly removed from jaws but not as easy as for pod extract / no observable breakage


The majority of the livestock farmers considered that feeding goats on foliage of P. juliflora had negative effects on the teeth and performance of the goats (Table 3). In addition, the majority of the farmers observed that the mature goats were the ones that were highly affected with regard to loss of teeth and reduced feed intake and were likely to have their performance and returns to the farmers greatly reduced.

Table 3. Farmers’ perceptions on negative effects ofP. juliflora (Mathenge) (n=90)

Farmers’ Perception



P Value





No effects



Don’t know



The study revealed that the consumption of the P. juliflora foliage greatly (90.0%) causes loss and breakage of teeth of the mature goats (Table 3). This impact negatively on the body condition (85.6%), feed intake (66.7%) and reduces the returns and profitability (18.1%) to the livestock farmers. In addition, it is expected there would be continued effects on the performance of the goats and other livestock is likely to reduce livestock production.

Table 4. Farmer observations on the effects on the goats from consuming Prosopis leaves and pods (n=90)




Reduced feed intake




Reduced body condition




Loss / broken teeth




Reduced returns




The study revealed that livestock farmers perceived P. juliflora to be a nuisance species as it was very invasive, encroached on pastureland and regenerated easily (Table 5). Its encroachment caused bushy thickets (Photo 1) that reduced pastures. In addition, most respondents observed that the thorns of P. juliflora were poisonous. Finally, encroachment by P. juliflora reduced the overall returns to the livestock farmers in the ASALs.

Table 5. Farmers’ perception on nuisance of P. juliflora ( Mathenge) ( n =90)

Farmers’ perception




Invasiveness / encroachment




Reduced pasture




Re-sprouting nature




Poisonous thorns




Photo 1. Thickets of P. juliflora along Mikuyuni riverine ecosystem in Kwa Vonza, Kitui (source: Mutavi)


Shitanda et al (2013) found that P. juliflora pods had high levels of several sugars: rhamnose, fructose, xylose, galactose and glucose. These sugars served as substrates for bacteria and form acids in the mouth of livestock. This concurs with current findings that the pods and leaf meal pastes were acidic within the period of study while the control treatment remained neutral. The acidic conditions created in the mouth of the goats are suspected to corrode the enamel of the teeth and causing loss and breakage of the teeth. This concurs with the current findings where the pods and leaf meal paste caused corrosion of the teeth and flexibility of the bones. In addition, these findings concur with observations by Shitanda et al (2013) that livestock loose tooth once they feed on foliage of P. juliflora. Shitanda et al (2013) further noted the negative impacts on the health and body condition leads to reduced feed intake and at times death of animals. This concurs with current findings on the farmers’ perception that foliage of P. juliflora caused reduced body condition, feed intake and return to the farmers.

Choge et al (2004) observed that P. juliflora is a very invasive species – which is expansively encroaching in the dry rangelands of the world including Kenya. In addition, due to the aggressive invasive nature of Prosopis species, P.juliflora was classified as an invasive species in the rangelands (GISP 2010). This concurs with current finding on the farmers’ perception on encroachment that P.juliflora was found to be a noxious and invasive species in the Kitui ecosystems, especially the riverine areas, thus reducing the coverage of the pastures in the rangelands. The Ministry of Agriculture Act (Cap 325) on suppression of noxious weeds in Kenya declared that P. juliflora was a noxious species, which is in agreement with Maundu et al (2009), that it needs to be controlled to prevent any further negative impacts on animal health, environment and livelihood sustainability. Under the Act (325), the owner of the land, where the noxious plant has become nuisant, may be forced to uproot the plant to control its agrresive invasive nature. This is in support to the public outcry of residents of areas where the P. juliflora has enormous invasiveness and health problems in livestock (Daily Nation 2005).

Weber (2003) noted that P. juliflora rapidly grows and forms dense thorny thickets, which re-sprouts easily when cut or uprooted. The thick tickets casts sufficient shade that suppress the underneath herbaceous plant species which forms critical vegetation base for livestock grazers (Maundu et al 2009). Opiyo et al (2014) further noted that the increasing colonization of the grazing lands by P. juliflora in semi-arid lands, like Turkana county, if not well managed, it will constitute to an ecological and socioeconomic threat to pastoral communities. This concurs with current finding that thickets are problematic in the riverine ecosystems in Kwa Vonza ward, Kitui rural sub-county in Kitui County and control measures are not able to combat the P. juliflora nuisance in the rangelands in Kenya. The respondents felt that control of this species is not successful and concurs with Maundu et al (2009) finding in which residents in Garissa County felt that they can do without the P. juliflora due to its negative impacts (fast invasiveness, thick bushlands and loss of pasture) in their grazing lands.



I acknowledge the support from the technical team at SEKU for the assistance in carrying out of the experiments for analyzing the pH of the pod and leaf meal. I also appreciate the co-operation of the respondents and key informants from Kwa Vonza ward, Kitui Rural sub-county in Kitui County.


Choge S K and Chikamai B N 2004 Proceedings of workshop on integrated management of Prosopis species in Kenya. 1st‐2nd October 2003, Soi Safari Club, Lake Baringo. Global Environment Facility, Kenya Forestry Research Institute and Forest Department.

Dairy Nation, May 19, 2005 An article: Kenyans to take FAO to World Court

GISD 2010 Global Invasive Species Database online data sheet. Prosopis juliflora ( shrub). Accessed March 2011

Maundu P and Tegnas B 2005 eds. Useful Treesand Shrubs for Kenya, World Agroforestry Centre, Nairobi.

Maundu P, Kibet S, Morimoto Y, Imbumi M. and Adeka R 2009 Impact of Prosopis juliflora on Kenya's semi-arid and arid ecosystems and local livelihoods. Biodiversity10: 33-50.

MoA 2005 Ministry of Agriculture. Development plan. Baringo District

Opiyo F E O, Wasonga O V and Nyangito M M 2014 Measuring household vulnerability to climate-induced stresses in pastoral rangelands of Kenya: Implications for resilience programming. Pastoralism: Research, Policy and Practice 4(10): 1–15.

Shitanda D, Mukonyi, K, Kagiri M, Simiyu L and Gichua M 2013 Properties of Prosopis juliflora and its potential uses in ASAL areas of Kenya. Journal of Agriculture, Science and Technology, 15(1).

Suppression of noxious wee ds Act 1983 Edition

Weber E 2003 Invasive Plant Species of the World: A Reference Guide to Environmental Weeds. CABI Publishing, Wallingford, UK.