Substitution effect of Noug seed cake (Guizotia abyssinica) with Korch /Eritrnia buruci/ leaf mealon growing Doyogena lambs fed on desho (Pennisetum glaucifolium) grass hay as basal diet

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Tesfaye Abiso¹ , Deribe Gemiyo²

¹Areka Agricultural Research Center, Areka, Ethiopia

²Central Ethiopia Agricultural Research Institute, CEARI, Durame, Ethiopia

Corresponding Author Email: tesfayeab2011@yahoo.com

DOI : https://doi.org/10.51470/AGRI.2025.4.3.16

Abstract

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Introduction

Despite possessing one of the large livestock populations in Africa- including 66.261 million cattle, 38.013 million sheep, 45.716 million goats and millions of other animals [1]-Ethiopia faces chronically low livestock productivity. The primary constraint is a critical shortage in the quantity and quality of feed resources [2], [3]. This is exemplified by the heavy reliance on natural grazing (57.8%) and low quality crop residue (29.8%), with only minimal use of improved feeds (0.38%) [1]. The scarcity of forage during dry season and the low energy density of available are major factors limiting animal performance [4]

Sheep production, a cornerstone of Ethiopian’s mixed farming systems, is under pressure from population growth, urbanization, and climate change.  The productivity of indigenous breed like Menz, Arsi-Bale, and Blackhead Somali) is often low in terms of weight gain and carcass yield [5].While import of exotic breeds with high dressing percentages to improve meat yield and quality. However, exotic breeds like Awassi and Corriedale were attempted to improve meat yield, these breeds have struggled to adapt to local management and climate [6]. Consequently, the rising demand and price for mutton over the past decade necessitate alternative strategies to enhance productivity. A promising approach is to improve the plane of nutrition for adapted indigenous breed through supplementation. Indigenous sheep are valued for their resilience to poor nutrition and disease, and community based breed selection programs are advocating for their genetic improvement as a solution [6].  The Doyogena sheep in particular, is recognized for its good fattening potential and growth capacity in the central Ethiopia region [9] [10]. Unselected male sheep from such programs need to be castrated and finished, but appropriate and cost-efficient feed formulation for this purpose are understood.  Developing feeding system that better utilize locally available resource is crucial for addressing the challenges of global warming and resource depletion [11] [12].  The multipurpose tree legume Erythrina brucei is one such potential nutrient source. Preliminary research has identified several E’. brucei provenances as a high-quality forage due to high dry matter and nitrogen degradation rates but its effect on animal performance requires investigation [13]. Therefore, this study aimed to determine the effect of supplementing Doyogena lambs with Erythirnia brucei leaf meal as a protein source. The specific objectives were to evaluate its impact on feed intake, weight gain, carcass traits and feed and economic efficiencies, thereby providing critical information for smallholder farmers facing widespread protein and calorie malnutrition.  

Material and Methods

Description of the study area

The study was carried out at the Mante Dubo Research Station, which operates as a sub-site of the Areka Agricultural Research Center. The station is located about 7 km northwest of the main center and roughly 306 km from Addis Ababa. It lies at 7°20’ N and 37°50’ E, with an altitude ranging between 1,900 and 2,800 meters above sea level. The area receives an average annual rainfall of 2,121 mm and supports a mixed crop–livestock farming system. These diverse agroecological conditions make the site suitable for testing agricultural technologies under variable field environments.

Preparation of Experimental Feeds and Feeding Procedures

The experimental feeds were desho grass (Pennisetum Pedicelatum)  hay, Doug seed cake meal, and dried E. brucie leaf meal. Desho grass hay was prepared at the Mante Dubo sub-station. It was harvested at an early stage (2 months of age), wilted, dried in the shade, and stored as hay at a moisture content of 10-15%. The hay was chopped into smaller pieces manually to facilitate the intake and palatability, and reduce selective feeding by the sheep.

Purposefully, young kroch leaf was harvested from 2-4 years old trees from nearby farmers’ land, which was already planted for the purpose of a living fence. The leaf was harvested manually during the rainy season (June- August) by hand-picking.   The leaves were subjected to air drying under the shade on a plastic sheet to keep the nutrient quality from deteriorating. The dried Erythrina brucei leaves were easily crushed by hand when pressed and packed in the sack, then stored in a dry place until the feeding trials were started.

Noug seed cake meal and wheat bran were bought from Hossana city of Jon farm oil and feed processing industry. The noug seed cake meal and Erythrina brucei leaves meal were mixed until the CP content became similar in each treatment.

The formulated feeds were offered daily at 8:00 am and 4:00 pm, and water and mineral salt licks were accessed freely to all lambs. Common for all treatments, 200 g of wheat bran was given in equal amounts for all lambs /day once to satisfy the daily energy requirements of lambs [14].

Animals, Housing and Management

Twenty intact male Doyogena lambs (aged 6-9 months) were procured from a local market and transported to Areka Agricultural Research Center, Mante Dubo sub-station. The age was estimated by dentition,  owner information, and overall appearance. Upon arrival, lambs were ear-tagged and quarantined for 15 Days, during which they were treated with albendazole and for parasite control. Following quarantine, the lambs were housed in individual pens, each equipped with a hay trough, and separate buckets for supplement and water, and subjected to a 15-day acclimatization period. The 90-day experimental feeding trial was conducted thereafter, with pens and troughs cleaned daily before feeding.

Experimental Design and Treatment Arrangement      

The study employed a randomized complete block design (RCBD) consisting of four dietary treatments. Lambs were initially stratified into five blocks based on their starting body weight, and animals with similar weights within each block were randomly assigned to one of the four treatments. This approach helped minimize variability and ensure balanced representation across treatments.

Data collection

Data collection focused on feed intake, body weight gain, digestibility, and carcass traits for all experimental lambs throughout the study period.

Feed and nutrient intake

The daily amounts of feed offered and refused were weighed for each lamb using a sensitive balance. A representative sub-sample (20% of the refusals) was collected daily for chemical analysis. Average daily feed intake (ADFI) was determined on a dry matter (DM) basis as the difference between the feed offered and the feed refused.

Body weight gain and feed conversion efficiency of the lambs

 The live body weight of each lamb was measured every seven days after an overnight fast, and for analysis these values were converted to fifteen-day intervals. Initial and final body weights obtained over the 90-day feeding period were used to determine total weight gain.

Average daily gain (ADG) was calculated by subtracting the initial weight from the final weight and dividing the difference by the total number of feeding days. Feed conversion efficiency (FCE) was determined as the ratio of ADG to average daily feed intake (ADFI), following the method described by [15].

Carcass characteristics

At the end of the feeding trial, all lambs were fasted overnight, and their slaughter body weight was recorded. Three lambs from each treatment group were then randomly selected for detailed carcass assessment. Slaughtering was carried out by severing the jugular vein and carotid artery, and the blood was collected and weighed immediately after exsanguination. Carcass dressing and systematic dissection followed. The skin was carefully removed to avoid tissue loss, and all major non-carcass components were separated and weighed individually. These included blood, skin, head, feet, kidneys (with fat), lungs, trachea, esophagus, heart, liver (with gall bladder), spleen, testes, penis, the entire gastrointestinal tract, tail, and tongue.

Empty body weight (EBW) was calculated as slaughter weight minus gut fill. Hot carcass weight (HCW) was recorded after removing the blood, skin, head, feet, gastrointestinal tract, and internal organs, following the procedures outlined by [16].

Dressing percentage was calculated on two bases:

•  (HCW) slaughter body weight x100
•  (HCW/EBW) x100

The rib-eye muscle area was measured by tracing the muscle surface between the 11^th and 12^th ribs onto plastic paper.  The following composite components were calculated:

 Edible offal (EO): sum of blood, kidneys, liver, omasum, abomasum, intestines, reticulo-rumen, kidney fat, tongue, heart, spleen, pancreas, and tail.

Not- eaten offal (NEO): sum of head (without tongue), feet, skin, esophagus, lungs, testis, penis, trachea, and gut content.

Usable products (UP): sum of hot carcass weight, edible offal, and skin.

Partial Budget Analysis

A partial budget analysis was conducted to evaluate the economic feasibility of the different treatments, following the procedure of [17].  This analysis accounted for all variable costs, (e.g. feed , vaccinations)  and the returns from the sale of lambs in each treatment.

Net return (NR) was calculated as:

NR=Total Returns (TR) –Total Variable Costs (TVC)

The marginal rate of return (MRR), which indicates the return per additional unit of expenditure, was calculated as:

MRR% = (ΔNR /ΔTVC) x100

 Where ΔNR is the change in net return and ΔTVC is the change in total variable cost between treatments.

Chemical Analysis

The chemical composition of the experimental feeds, refusals, and fecal samples was analyzed at the College of Agriculture, Arba Minch University (AMU). Representative samples of korch leaf meal, noug seed cake, and refused desho grass hay were ground to pass through a 1-mm sieve prior to analysis. Dry matter (DM), organic matter (OM), crude protein (CP), ash, crude fiber (CF), and ether extract (EE) were determined following the procedures outlined by [18], with crude protein quantified using the Kjeldahl method. Neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were analyzed according to the methods of [19]. For apparent digestibility determination, 20% subsamples of feces collected from each lamb were composited and analyzed for DM, OM, CP, ash, NDF, and ADF. The metabolizable energy (ME) content of the feeds was estimated from digestible organic matter (DOM) using the equation described by [15].

Data analysis 

Data on feed intake, nutrient digestibility, body weight change, and carcass characteristics were analyzed using analysis of variance (ANOVA) under the General Linear Model (GLM) procedure of the Statistical Analysis System (SAS, Version 9.3). Correlations among feed intake, digestibility, and body weight gain were also computed. When significant differences were detected, treatment means were separated using the Least Significant Difference (LSD) test at the 5% significance level.

The model used for analyzing the experimental data was:

Result

 Chemical composition of Experimental feeds

The chemical composition of the feeds used in the experiment is presented in Table 2. All feed samples were analyzed for dry matter (DM), organic matter (OM), ash, crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin (ADL).

Feed Intake, Growth Performance, and Feed Efficiency

Feed intake, average daily gain (ADG), and feed conversion efficiency of the experimental sheep are summarized in Table 3. Lambs receiving the T1 diet showed significantly higher (p < 0.05) total weight gain and ADG compared to those fed the T4 diet. Daily dry matter intake was also greater in the T1 group. Over the 90-day feeding period, the overall mean ADG for all lambs was 53.2 g/head/day. However, except for the difference observed between T1 and T4, ADG did not vary significantly among the remaining treatments. Likewise, initial body weight, final body weight, total dry matter intake, and feed efficiency (gain/feed) showed no significant differences among treatment groups.

Weight change trends

The body weight of the sheep increased over 90-day experimental period. While lambs fed higher level of Erythrina brucei leaf showed a decreasing trend in weight gain compared to those on lower levels, the overall differences in body weight across the weeks were not statistically significant (p>0.05). The trends of weight gain is illustrated in Figure 1.

Carcass characteristics

The carcass characteristics of sheep fed the experimental diets are presented in Table 4. Substituting noug seed cake with Erythrina brucei leaf did not produce any statistically significant differences in slaughter weight, empty body weight, hot carcass weight, or dressing percentage. Lambs in the T2 group showed a numerically higher empty body weight, although the difference was not significant. The overall mean dressing percentage based on slaughter weight was 37.54%. Similarly, hind and forequarter weights, lumbar vertebrae measurements, rib and rib-eye muscle areas showed no significant variation among treatments.

Edible offal components

The weight of edible and non-edible offal components are presented in Table 5and 6 respectively. None of the offal components-including heart, liver, fat, head, skin, and lungs-were significantly affected by the dietary treatments. While there were numerical variations (e.g. total fat was lowest in T4), these differences were not statistically significant (p>0.05). Table 5 Edible offal components (g) of Doyogena sheep

Partial budget estimation

An economic analysis using partial budget estimation was conducted  (Table 7). The net profit per head over the 90-day experimental period was higher for the T4 diet at 2059.82 ETB, followed T1 (1813.39 ETB), 1699.78 ETB for T2 and  1681.58 ETB for T3.

Discussion

Feed intake and feed conversion efficiency

Feed intake is influenced by multiple factors, including feed type, texture, physical form, environmental conditions such as temperature, and the presence of anti-nutritional factors [20]. The proportion of energy to protein in the diet is also a critical determinant. In this study, the inclusion of Erythrina brucei leaf resulted in a higher Feed Conversion Efficiency (FCE), a finding consistent which previous research on the value of korch leaf for growing lambs [21]. Such locally available, protein-rich feeds and fodders are both affordable and accessible for smallholder farmers. Several major local protein sources have already been identified for use in the crop-livestock systems of central Ethiopia [8], while other feed categories have been noted as inadequate for supporting growth [22]. The results indicate that dry matter (DM) intake was statistically similar (P<0.05) across all treatment groups of sheep (Table 3). Consequently, no significant differences in intake were observed among the supplemented animals.  DM intake was observed for all treatment sheep receiving diets (Table 3). Therefore, no significant differences were observed among the supplemented animals.

Pattern of weight changes

In rural communities, it is common practices to sell lambs once they achieve optimal growth, as prolonged increases production costs [22], [10], [23], [21]. A key management strategy for improving productivity is therefore to maximize weight gain while minimizing labor and feed expenses. Weight gain is itself affected by feed preparation (physical or chemical treatment), feed quality (energy and protein content), environmental temperature, and the health of the animals.  In the present study, no weight losses occurred during the experimental period. The use of an efficient grower ration could enable lambs to reach export market weight (25-30 kg), within a short period, such as three months. This is particularly advantageous given recurring feed cost inflation. To farther shorten the finishing period, supplement level could potentially be adjusted. For export market, over-fattening is unnecessary and cost-ineffective, as it primarily leads to fat deposition once animals have reached optimal growth. While animal weight can fluctuate due to factors like feed texture of health, the sheep supplemented with increasing level of Erythrina brucei leaf exhibited a consistent weight increase throughout the study. This aligns finding from [23], who reported a similar study weight gain in oxen fed local energy-rich feeds, this trend is not always linear and can be influenced by animal health, feed forms, and environmental temperature [22]. The weight gain observed in this research was higher than that of reported for goat fed Erythrnia brucei leaf [24] and for sheep fed sensel (Justicia Schemperiana) leaf meal [21].  

Carcass characteristics

Carcass yield and composition are direct functions of an animal’s diet. The higher slaughter weight (SW) and empty body weight (EBW) in sheep the T1 supplemented could be attributed to the high protein level released from Erythrina brucei; this effect declined at higher inclusion levels. This suggests that the higher level of noug cake supplementation may have limited DM intake, metabolizable energy (ME) intake, nutrient digestibility, and dressing percentage. This is supported by [25], who found that dressing percentage increases with higher total DM and nutrient intake. The lack of significant differences in dressing percentage (DP) and hot carcass weight (HCW) among sheep supplemented with various level of Erythrina brucei leaf may be due to the partitioning of weight gain between carcass and non carcass components, which minimized differences between groups.  This finding is consistence with [27], who observed similar DP in Gaddi sheep across nutritional planes, indicating that nutrition did not significantly affect this trait, the DP values on EBW from this study are higher than the values of 41.34 % and 41.79%, and 39.9% reported by [28], [21] for Somali and Mid-Rift Valley sheep raised on concentrate-based diets.

Partial Budget Estimation

Profitability is essential for both private enterprises and smallholder farmers to sustain sheep fattening operations. In the mixed farming systems of the central-south region, the benefits of growing and fattening enterprises have been well documented [22, 23]. Energy-dense feeds are particularly important for accelerated fattening during festive seasons, as they enable faster weight gain, reduce labor and feed costs, and improve overall profitability [23]. Farmers in these areas have also developed informal insurance schemes to increase the number of fattening animals while minimizing risks such as mortality, theft, or loss [22]. Access to credit can further enhance these practices by providing the resources needed for strategic, holiday-targeted fattening. In the partial analysis shown in Table 7, treatment T4 recorded the lowest performance compared to all other treatments.

Conclusion

The study demonstrated that feeding korch (Erythrina brucei) leaf to growing lambs resulted in a satisfactory mean daily gain of 53.2 g/day over three months, indicating its potential as a viable feed resource for both smallholder farmers and private enterprises. Partial budget analysis further confirmed the economic feasibility of strategic supplementation. The lack of significant differences among treatments suggests that korch leaf could effectively replace noug cake meal or commercial concentrates with locally available protein-rich sources for Doyogena sheep. Further research is recommended to evaluate potential antinutritional effects and to determine the optimal and higher inclusion levels for improved growth performance.

Acknowledgments

The authors thank Areka Agricultural Research Center (AARC) and South Ethiopia Agricultural Research Institute (SEARI) for supporting and funding this study.

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