Livestock Research for Rural Development 22 (9) 2010 Notes to Authors LRRD Newsletter

Citation of this paper

Performance of growing Small East African Goats offered Rhodes grass hay and supplemented with a 1:1 mixture of Maerua angolensis: Zizyphus mucronata leaf browses

J O Ondiek*, S A Abdulrazak*,** and E N Njoka***

* Egerton University, Department of Animal Science, P.O. Box 536-20115, Egerton, Kenya
** National Council for Science and Technology, P.O. Box 30623-00100, Nairobi, Kenya
*** Chuka University College, P.O. Box 109 Chuka   ;


A 56-day experiment was conducted to examine the contribution of Maerua angolensis and Zizyphus mucronata, mixed on a 1:1 ratio as a supplement to growing Small East African Goats fed a basal diet of Chloris gayana hay. Twenty goats were assigned to five treatments of:  0, 15, 20, 25 and 30 g DM kg-1W0.75, assigned as MZ0, MZ15, MZ20, MZ25 and MZ30.


The total extractable phenolics (TEPH) and total extractable tannins (TET) for Maerua angolensis (11.4, 3.01 mg kg-1 DM) were lower than for Zizyphus mucronata (72.3, 41.2 mgkg-1DM) and the mixture had average values (41.9, 22.1 mg kg-1 DM), respectively. The Chloris gayana hay had low crude protein content (54 g kg-1 DM). Intake of hay and of total DM, and coefficients of apparent digestibility of diet proximate components, increased with supplementation. The control animals (MZ0) lost weight and the supplemented groups gained weight with best growth on the MZ20 diet. Rumen pH was in the normal range but rumen ammonia N was low for the control diet (8.99 mg 100ml-1), increasing with supplementation to 11.3 - 12.7 mg 100ml-1.  There was a positive linear relationship between rumen ammonia level and live weight change.


It is concluded that the 1:1 mixture of Maerua angolensis:Zizyphus mucronata with a CP of 261g kg-1 DM is an adequate protein supplement for growing Small East African Goats when fed a low quality (5.4% CP) basal diet of Chloris gayana hay.

Key words: Digestibility, forage mixture, indigenous browse, intake, rumen ammonia


In arid and semi arid regions Kenya, goats are normally kept under an extensive grazing system. They mainly depend on rangeland pastures that are deficient in nitrogen and digestible nutrients for optimum fermentative rumen digestion (Van Soest 1982), thus low intake which can be improved by tree fodder supplementation (Topps 1992, Abdulrazak et al 2000). Norton (1994) reported that when the basal diet quality is higher, lower level supplementation at 0.5 of live weight or 15% of DMI is probably sufficient, whereas normal gains can be achieved by supplementing at 1.0 - 1.5 % of live weight or 40 - 60 % of DMI. Kanjanapruthipong and Leng (1998) reported improved performance of rams fed poor quality grass diets and supplemented with Gliricidia maculata at an optimum level of inclusion of 20 - 25%.


The tree browses, however, contain tannins that may adversely affect utilization (Makkar el al 1989, Makkar 1993). Hence, mixtures of  tree foliages may help to dilute the concentration of these anti nutritive agents. They have been shown to increase palatability and intake (Devendra 1990,  Rosales and Gill 1997) as well as diet digestibility (Phiri et al 1992) and growth  (Bosman et al 1995). In the free range, goats feed on random mixtures of the available fodders even when these are among the preferred feed. This helps to optimize on nutritional intake to meet their requirements.


The objective of this study was to examine the effects of supplementation of 1:1 leaf mixture of Maerua angolensis and Zizyphus mucronata on voluntary feed intake, diet digestibility and growth performance for Small East African goats fed a basal diet of Chloris gayana hay.


Materials and methods 



The Maerua angolensis and Zizyphus mucronata leaves were harvested at the Egerton University Chemeron field station in Baringo, in the Lower Midland agro-ecological zone (LM5), and 1,080 m above sea level, with an annual mean temperature of 23C and 700 to 950 mm of rainfall per year with peaks in the April/May and July/August rain seasons. The two browse species were selected based on previous studies on their proximate composition, palatability, and in- vivo and in- vitro degradation.




Twenty Small East African Goats with an initial average live weight and age of 13.8 (s.d 1.2) kg and 7 months, respectively, were used. All animals were treated against internal parasite s using Nilzan+ (Coopers Ltd) and sprayed with Triatix (Coopers Ltd) before commencement. All goats were kept in a house and confined in individual, well-ventilated raised slatted floor cages and were weighed weekly for 8 weeks. The animals were allocated to five diets each with four goats with equal live weights on each treatment..




Rhodes grass (Chloris gayana) hay was purchased in Elementaita, Nakuru, and was milled through a 4mm mesh to minimize wastage and preferential selection. Maerua angolensis and Zizyphus mucronata leaf forage was harvested from mature plants in Marigat, Baringo, and stems were removed to ensure uniformity of the forage. They were dried for 7 days in a well-ventilated iron roof shed to avoid bleaching and the dry forage was later milled through a 3.5 mm screen to produce the Maerua angolensis and Zizyphus mucronata meals. These were mixed in a 1:1 ratio on DM basis and then stored in gunny bags for use in the experiment. Maize germ meal was purchased from a commercial firm. Additionally, the animals were offered 15g daily of Maclik salt (Coopers K (Ltd)) that contained: NaCl 27.00, Ca 18.01, P 11.00, Mg 3.00, Fe 0.5, Cu 0.16, Mn 0.4, Zn 0.5, S 0.4, Co 0.02, I 0.02, Se 0.001, Mo 0.002, with a Ca:P ratio of 1.08:1).




The five treatment diets were offered in a completely randomized block design (RCBD) with 4 animals per treatment and the animals, with an initial weight of 13.8▒1.2kg were blocked on live weight. The mixed forage supplement was offered at 0 (control), 15, 20, 25 and 30 g DMkg-1W0.75, designated as MZ0, MZ15, MZ20, MZ25 and MZ30.


Chopped Chloris gayana hay basal diet was offered at 0830hr and 1430hr allowing a proportional refusal of 20% of total daily amount offered. Basal diet and supplement were adjusted weekly based on animal’s weekly body weight. Feed refusals were collected and weighed separately for individual animals in the morning before fresh feeds were offered and daily intake was calculated by difference. Feeds offered were sampled fortnightly and bulked for proximate analysis. After the feeding trial, a nutrient digestibility trial was conducted.


Feces collection, rumen pH and NH3-N


After the feeding trial, total collection of daily faeces output of all goats was done for 7 days, the faecal weight recorded and afterwards, 10% portions of the 24 hr faeces were taken, oven dried at 60oC for 48 h and stored for later chemical analysis. The dry faeces and feed samples were milled through 2 mm screen and stored in polythene bags for chemical analysis. During the last three days of the digestibility trial, approximately 10 ml of rumen liquor was collected from the goats before supplement was offered and thereafter 2, 4, 6 and 8 h post feeding, using a stomach tube. The pH of the sample was determined immediately using an ionizable pH meter and the sample was then strained through a double layer of clean cheesecloth. About 10ml of the liquid fraction was sampled, acidified with 2ml of 10% H2SO4 acid and stored at-20oC for later analysis of NH3-N.


Analytical methods


Proximate fractions (DM, OM, CP, ADF, NDF and ash) in feed and feces; and N in feeds, feces and rumen fluid were determined according to standard procedures of the Association of Official Analytical Chemists (AOAC1990). The Kjeldahl nitrogen N content in feeds and faeces was then converted into CP, calculated as (N x 6.25). Neutral detergent fibre (NDF) and acid detergent fibre (ADF) were determined by the method of Van Soest et al (1991). Phenolics were extracted using 70% aqueous acetone. Total extractable phenolics (TEPH) were determined using Folin Ciocalteu procedures as described by Makkar  (2000). The concentration of TEPH was calculated using the regression equation of tannic acid standard. Total extractable tannins (TET) were estimated indirectly after being absorbed to insoluble polyvinyl pyrrolidine (PVP) and the TET concentration calculated by subtracting the TEPH remaining after PVP treatment from the initial TEPH.


Statistical analysis


Data on DMI, ADG and digestibility were subjected to analysis of covariance using the General Linear Model of Statistical Analysis System computer package (SAS 2000), where initial live weight was a covariate in the analysis of DM intake and live weight changes. An F- test at 5 % probability level was used to test for significance and significantly different means separated using Duncan's New multiple range test (Steel and Torrie 1980).


Results and discussion 

The chemical composition of feed offered is shown in Table 1. 

Table 1.  Chemical composition (g kg-1DM except por DM which is on air-dry basis)) of Maerua angolensis, Zizyphus mucronata and their 1:1 mixture and Chloris gayana hay offered to Small East African Goats.










Maerua angolensis









Zizyphus mucronata









1:1 mixture


















 nd= not done

Rhodes grass hay had the highest NDF content (528gkg-1 DM), comparable to that reported by Ondiek et al (1999) and Ondiek et al (2000) whereas it was lowest in the supplement mixture (421 g kg-1 DM). The CP of the hay (54.3 g kg-1 DM) was below 7%, indicated as the minimum for microbial growth and optimum roughage intake (Minson 1981; Preston and Leng 2009). The CP of the supplement at 261g kg-1 DM was within the range earlier reported in the work of Shayo et al (1997) and Coppock (1993)  but higher than what is reported for other tree forage species (Abdulrazak et al 2000). This variation could partly be attributed to species, site, variety, part harvested and stage of maturity (Topps 1992, Osuga et al 2006).


The pH values (Table 2) were within the optimum range for microbial growth and fiber digestion (ěrskov 1982). The NH3-N concentration increased from 8.99 to 12.7 mg 100ml–1. These concentrations are higher than the 50 – 80mg l-1 requirement for optimum rumen function as indicated by Satter and Slyter (1974), but closer to those recommended for microbial digestion of crop residues (Perdok and Leng 1989). This indicates the presence of adequate rumen degradable nitrogen supply for rumen fermentation.

Table 2.   Dry matter feed intake, average daily gains, rumen ammonia nitrogen and apparent nutrient digestibility of Small East African goats fed Chloris gayana hay and supplemented with1:1 mixture of Maerua angolensis and Zizyphus mucronata








Supplement level, g kg-1 MW0.75







DM  intake, g/d














  1:1 Maerua angolensis: Zizyphus mucronata














Total DM intake, % BW







Daily gain, gd-1







Rumen NH3-N, mg100ml-1







Rumen  pH







Apparent digestibility, g/kg-1DM

  Dry matter







  Crude protein







  Organic matter







  Acid detergent fiber







  Neutral detergent fiber







a, b Means on the same row with different superscripts are different at P<0.05

SEM- Standard error of the mean

The growth rates of the goats were negative on hay alone (Table 2), and positive with all supplement levels with best result on the MZ20 diet. These results are similar to what Njuguna 2004 (MSc. Thesis, unpublished) reported for goats fed Chloris gayana hay and supplemented with mixtures of Acacia tortilis leaves and pods (range 12.6 to 23.6 gd-1. Rumen ammonia levels were lowest on hay alone and highest on the MZ20 diet. The increase in weight gain appeared to be associated with the supply of ruminal fermentable N (Figure 1) providing a substrate for enhanced microbial growth and protein synthesis.

Figure 1.  
Relationship between rumen ammonia level and live weight change

Supplementation with leaf forage significantly improved  the coefficients of digestibility of all proximate constituents (Table 2).  Mixing of the forages could have led to synchronized fermentability of individual chemical constituents leading to associative effects in DM intake and digestibility (Sinclair et al 1995, Rosales and Gill 1997).


Protein status of poor quality roughage has limiting effects on the intake (Kempton et al 1978) and supplementing with protein increases the rumen outflow rate that stimulates the intake. Mixing of the two MPTS probably improved diet palatability through dilution of anti-nutritive factors including fiber (Devendra 1990) resulting to an associated improved dry matter digestibility and intake. Similarly Mtenga and Shoo (1990) and Bosman et al (1995) reported improved intake on supplementing with browse and forage mixtures.




The authors are grateful for the financial support from the family and the facilitation given by the department of Animal Sciences in laboratory analyses. The support from the Tatton Demonstration Farm (TDU) of Egerton University is acknowledged.



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Received 3 December 2008; Accepted 28 July 2010; Published 1 September 2010

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