Traditional management systems and linear body measurements of Washera sheep in the western highlands of the Amhara National Regional State, Ethiopia

Taye Mengistie^1,2, Abebe Girma², Gizaw Solomon³, Lemma Sisay³, Mekoya Abebe³ and Tibbo Markos^3,4,5

¹Andassa Livestock Research Centre, PO Box 27, Bahir Dar, Ethiopia
²Hawassa University, PO Box 5, Awassa, Ethiopia
³Debreberhan Agricultural Research Centre, PO Box 112, Debre Berhan, Ethiopia
⁴International Livestock Research Institute, PO Box 5689, Addis Ababa, Ethiopia
⁵International Center for Agricultural Research in the Dry Areas, PO Box 5466, Aleppo, Syria
mengistietaye@yahoo.com

Abstract

A study was conducted to describe the production systems and management practices and investigate the physical linear body measurements of Washera sheep in the traditional farming systems in the western highlands of the Amhara National Regional State, Ethiopia. Data was collected using focus group discussion and field measurements.

The agricultural production system in the study area was mixed crop-livestock. Livestock production and crop production complement each other in such a way that livestock are used as a source for draft and manure for crop production and from crop production the crop residues, straws and aftermath serve as main components of livestock feeds in the study areas. The main component of feed for sheep is communal pasture. Farmers house their sheep throughout the year together with other livestock separated by a woodlot. Breeding is allowed year round. Docking the fat tail of ewe lambs, for ease of mating, is a common practice.

The average flock size per household obtained in the present study was 9.58 sheep. The total flock age composition was 52.2, 9.9, 8.3, 5.2 and 24.3%, young stock with milk teeth, sheep with 1 pair of  permanent incisor (PPI), 2 PPI, 3 PPI and 4 PPI & above, respectively. The overall least squares mean of body weight, wither height, body length, heart girth, pelvic width and ear length obtained were 26.7±0.45 kg, 69.0±0.36 cm, 57.7±0.33 cm, 74.4±0.49 cm, 14.3±0.12 cm and 9.73±0.08 cm, respectively. The fixed effects of district, sex, dentition and the interaction between sex & dentition were sources of variation for the most of the response variables. The high correlation coefficients observed between body weight and heart girth for all dentition groups suggest that heart girth alone or in combination with other body measurements could provide a good estimate for predicting live weight of Washera sheep at different dentition groups. The differences in the coefficient of determination of the equations fitted between different dentition groups indicated that weight can be estimated using different equations for different age groups with different accuracies.

Key words: docking, heart girth, Quarit, weaning methods, Yilmanadensa

Introduction

Ethiopia with its extremes of variable agro-climatic conditions and ecological systems is endowed with diverse (18) populations (Tibbo 2006) and large number (21 million) (CSA 2006) of sheep. Among the diverse sheep populations, the Washera sheep is the one which inhabit the western highlands of the Amhara national regional state (Sisay 2002). The breed has a population of around 1.22 million (CSA 2006) and are possibly one of the most productive Ethiopian sheep breeds (Chipman 2003).

The Washera sheep also called Dangla sheep is characterised by large body size, wide fat-tail usually curved upward tip, horizontally carried or semi-pendulous long ears, both sexes hornless and slightly concave facial profile. These sheep have long thin legs, long neck, and prominently protruding brisket. Plain, patchy and spotted patterns of coat colour to which reddish brown with white patches or spots usually on the forehead and lower parts of the legs, plain reddish brown and plain white are dominant colour types (Sisay 2002).

A primary procedure for any future improvement in genetic resource utilization and conservation is to describe the breed/type and its production system. Information on the description of body measurements of Ethiopian indigenous sheep in general and Washera sheep in particular is sparse. The objective of this study was to collect data on the production system and morphological characters of indigenous Washera sheep kept under the traditional management system of the north western highlands of Ethiopia.

Materials and methods 

Study area     

The study was conducted on on-farm flocks of two districts in the north-western highlands of Ethiopia. The first district, Yilmanadensa, is located between 11^o10’-11^o15’N and 37^o30’-37^o40’E, about 60 km south-east of Bahir Dar, the capital of Amhara National Regional State. The second district is Quarit. It is located between 11^o00’N and 37^o20’-37^o30’E, about 280 km south of Bahir Dar. The study districts and flocks were selected purposively to superimpose on the ongoing ‘Community- and Conservation-based Improvement Scheme (program) for Washera Sheep’ project. Both the study areas lie within an altitude range of 1500 to >3000 m a.s.l. The study areas have one rainy season (kiremt), which extends from mid-May to October and all the remaining months (November to mid-May) are categorised as dry season. Estimated average minimum and maximum air temperatures in the two districts are 13 and 24 degree Celsius, respectively (ENMA unpublished).

Data collection

Data was collected during August 2007. Participatory rural appraisal (PRA) with a focus group discussion was used to investigate and understand the general sheep production system of the area. For the PRA study a check list focused on the major agricultural system, major crops produced, major livestock produced, sheep production (management and marketing, feeds and feeding, reproduction management etc.) was used.

For the morphological study, all sheep (n=650) in the study flock above 9 months of age were measured. Weight measurement, the live weight of an animal, was taken using the Salter scale (50 kg capacity with 200 gram precision). Other body measurements (heart girth, wither height, body length, pelvic width and ear length) were taken using flexible metal tape (3 meter length) to the nearest 0.5 cm after restraining and holding the animals in an unforced position. The reference points taken were: heart girth - the circumference of the chest posterior to the forelegs at right angles to the body axis; wither height - the highest point measured as the vertical distance from the top of the shoulder to the ground (bottom of forelegs); body length - horizontal length from the point of shoulder to the pin bone; pelvic width - horizontal distance between the extreme lateral points of the hook bone (tuber coxae) of the pelvis; and ear length - length of the external ear from its root to the tip (Figure 1).

All data collected from this field research was entered, cleaned and managed using Microsoft Excel computer program.

Statistical analysis

Analysis of variance of fixed effects of location, sex and dentition on body measurements were done by the General Linear Model procedures of Statistical Analysis System (SAS version 9.1).

The statistical models used were:

Y_ijk = µ + D_i + S_j +T_k + (ST)_jk +e_ijk                                                               Model 1

W = a + bG (linear)                                                                                       Model 2

W = a + b₁G₁ + b₂G₂ +… + b_nG_n (Multiple linear)                                        Model 3

Where:

Y_ijk = The observation on body weight and other linear body measurements;
W = The observation on live weight of the animal;
µ = Overall mean;
D_i = Fixed effect of district (i= Yilmanadensa, Quarit);
S_j = Fixed effect of lamb sex (j = Female, Male);
T_k = Fixed effect of dentition (k = 0, 1, 2, 3, 4);
(ST)_jk = the interaction effect of sex with dentition;
a = Intercept;
b= Regression coefficient of weight on body measurements;

G = Body measurements;
n = n^th number of body measurement;
e_ijk = effect of random error

 For the analysis of fixed effects of linear body measurements Model 1 was used. For all linear measurements dentition was grouped as 0 - sheep with milk teeth (above 9 months); 1 - sheep with one pair of permanent incisor (PPI); 2 - sheep with two PPI; 3 - sheep with three PPI; 4 - sheep with four PPI and above.

For the prediction equation of weight using body measurements, models 2 (linear) and 3 (multiple linear) were used. The statistical analysis was carried out using statistical package for social sciences (SPSS version 13.0) linear regression procedures. Live weight was regressed on body measurements separately for different age groups and for overall. In the multiple regression equation, prediction equations were developed for live weight using a stepwise multiple regression procedure in which the number of predictors to be selected and the order of entry are both decided by statistical criteria (Field 2005).

Results and discussion  

Description of the production system

The agricultural production system in the study area was mixed crop-livestock. Crop production was the main agricultural activity for the livelihood of the smallholder farmer in both study areas. The major crops grown include teff, maize, chickpea, barley, grass pea, field pea, faba bean and wheat. Cattle, sheep, donkey and poultry were main livestock species reared by the farm household. Some people practiced apiculture. Cattle were mainly kept for draft power (ploughing) from oxen, production of oxen and small milk from cows. Sheep and poultry were kept for cash income (sale) and for home consumption.

Livestock production and crop production complement each other in such a way that livestock are used as a source for draft and manure for crop production and from crop production the crop residues, straws and aftermath serve as main components of livestock feeds in the study areas. This type of complementarity in mixed crop-livestock production systems is well documented in the literature (Getahun 2008).

Livestock graze on communal grazing land which is owned by about 10 farmers (the area of land and number of households varies from area to area) and on crop stubble after harvesting. Most farmers own private grazing land for morning and afternoon grazing. Shrinkage of the communal grazing land from time to time due to cultivation and increased population pressure are the critical and major threats in addition to land slide and erosion (gully) in the highlands of Ethiopia (Getahun 2008; Mengistie 2008).

Though sheep production contributes in the household income to a great extent, it has long been taken as a side activity. However, the trend is that due to the decreasing grazing land and increasing population pressure, sheep are becoming very important and increasing from time to time. During focus group discussion, the key informants did mention that because of their suitability to produce and reproduce under feed shortage and with the increased market value, sheep are getting more attention at present.

Sheep production and management

Feeding

Sheep are herded together with other livestock species during the day. Like other parts of the highlands of the country, the main feed source is communal grazing land, crop residues and crop stubble (Abebe 1999; Getahun 2008; Tesfaye 2008). During crop harvesting season and in the afternoon, farmers remove their animals from the group-flock and graze them in their respective private grazing land and crop aftermath. Sheep had no access to hay and straw collected for dry season feeding. Some farmers in the study areas are recognising the difference of supplementing or not supplementing during feed shortage times. Priorities are given to pregnant, suckling and castrate animals when supplementing. The supplements are grass-pea straw, sprouted bean, local brewery bi-product “atela” and salt.

Housing

Farmers in the study area house their sheep throughout the year to protect them from cold and rain, predators and theft. They are housed usually together with other livestock to which it is separated by a woodlot. But some farmers with large flocks have separate housing for their sheep. In both cases it is usually built adjacent to the family house. Some farmers with small flock size tie their sheep to a peg. According to the information of the members of the focus group, there is a difference in the productivity of sheep between those tied and housed freely, i.e., tied animals were healthier and productive than those housed freely. Farmers explained this as sheep housed freely lay one over each other because of their social behaviour and also in need of the warmth from huddling. Pregnant animals, young lambs and weak animals are the most vulnerable groups. In addition, animals may not get enough rest at night.

Newborn lambs in the first week of birth are separated from their dam and cared for at home during the day when sheep are taken to grazing and before they get into their house upon their return in the afternoon. This is a common practice in other parts of the country (Abebe 1999; Mengistie 2008; Tesfaye 2008). Farmers use large baskets to keep newborn lambs and allow lambs to be kept dry, clean and warm. Suckling occurs in the morning before the dam leaves for grazing and when the flocks are back from grazing in the afternoon. Some farmers separate the dams for at least the first week of parturition and provide care for both lambs and dams indoors. These increase the dam-lamb bond and help to protect the lamb from chill, sun and other environmental stresses thereby increase lamb survival (Mukasa-Mugerwa et al 2000).

Disease prevalence and control

There is a low incidence of disease load in the study areas. Nonetheless, occasionally there might be disease outbreak during which many sheep would die because of lack of health support. Some of the symptoms of diseases in the area mentioned were death, shivering, coughing, diarrhoea, bloating, haemorrhage and wound around ear and mouth and legs, loss of appetite, mucus and frowsy mouth, dropping ear and head. Apart from taking to health clinics, farmers treat their animals by drenching with the juice of different herbs, bleeding from ear cuts and ironing and puncturing the abdomen when bloating. Most of the time, however, they die. Abortion was an important problem of sheep production in the area mentioned. Fearing these, many farmers are reluctant to keep as many sheep as they need.

Reproduction

Reproduction occurs year-round although most lambings are concentrated in August and February. This is because of better feed availability. Ewes lambing in August conceive in February and March when most crop types get threshed (sheep have access for straw and by-products on the farm), and those lambing in February conceive in August and September when the grazing condition is better. This is true for any other breeds of sheep in Ethiopia (Getahun 2008; Girma 2008). Mating was uncontrolled: any ram in the flock would mate with any in-heat ewe. There is a problem of breeding ram; farmers sale good conformation ram lambs before they reach puberty. This is because they can fetch better money. If any, those were of poor conformation (condition) that could not be sold. In fact, some farmers had their own ram tied at home and a farmer does not allow his ram to mate other farmers’ ewes.

Docking

Cutting the fat tail of female sheep is a common practice in both study areas. Sisay (2002) reported that more than half of the breeding females in the western highland sheep were docked. There is no standardised specific site of cutting. The practice is that almost all of the fat tail would be cut (Figure 2).

This is intended to facilitate mating and improve conception rate, improve body condition and not least to use the cut tail for consumption while the sheep are still alive. The cutting is done at the age of 2 – 3 months age, after weaning and they used a hot sharp knife to avoid bleeding and infection.

Weaning

There is no apparent target weaning age. But when suckling is prolonged and if lambs are of good body condition, farmers wean their sheep by covering the udder of the dam with a piece of cloth (Figure 2), smearing the teat with dung and separating the dam from the lamb. This is usually done after three months of age of the lamb.

Culling

Culling of unproductive animals is not common in the study area. Old ewes are maintained for long period of time even to the 12^th lambing. Ewes can be kept with no production for years. Farmers do not want to sell or slaughter those sheep that served the family. But today, this type of sheep management is changing.

Castration

Castration of sheep is not a common practice in the study areas. Some farmers with better wealth status, however, castrate and fatten two to three castrates for long period (1-2 years) for home consumption as well as for market. The method of castration is traditional by repeatedly crushing the cord above the testis using a smooth river-stone and wood. The age of castration is not fixed, but it is usually after the one pair of permanent incisors is seen. This is because the farmers believed that the rams will mature and finishes growth at this age.

Marketing

Though sheep are sold anytime in a year and as cash is needed, most are sold during holidays. Most ewe and ram lambs are sold just at weaning before they lose condition because of weaning shock. It is the ram lambs that are usually sold for meat at the market. Ewe lambs are sold for reproduction at the village level. Ewe lambs of healthy and better producing flock can be sold (pre-paid with better price) even earlier than two weeks of age by convention between the owner and buyer to take at weaning. This is to have better producing genotype. Through this they are selecting for flock characteristics. They are, however, unintentionally selecting against fast-growing desirable genotype ram lambs. This is because those good looking with high growth ram lambs are sold out from the flock before they reach breeding age. Since there is no controlled breeding, ram lambs which are not sold because of poor growth and conformation have the best chance to mate the flock.

In both areas, there is a nearby market to sell their sheep and there is a trend of marketing within the village (especially for breeding purpose). Market access was not mentioned as a problem in the study areas.

Flock size and demography

The average flock size per household and flock composition by age and sex in the study is presented in Table 1. The average flock size per household obtained in the present study was 9.58 sheep. Flock size ranged from 1 to 29 head of sheep. A similar result was reported for the same sheep at Quarit by Chipman (2003). The average holding of sheep (9.58) was higher than the 5.0 sheep/household reported from Alaba areas (Tsedeke 2007) and the 6.97 sheep per household around Dire Dawa (Aden 2003). However, it is lower than the 16.0 sheep per household in Gumuz sheep (Solomon 2007), and 24 sheep per household in Lallo Mama Midir in the central highland of Ethiopia (Abebe 1999).

Flock composition in terms of sex and age classes has been taken as an indicator of the management system that reflects to some degree the management objective, flock productivity and constraints on the system (Ibrahim 1998). In the present study, the total flock composition was 52.2, 9.9, 8.3, 5.2 and 24.3%, young stock with milk teeth, sheep with 1 PPI, 2 PPI, 3 PPI and 4 PPI and above, respectively. Of the young stock, 60.2% were females, 38.7% males and the rest 1.1% were castrates. This suggests that since a 1:1 male to female ratio is expected, more ram lambs were already sold from this age group.

Of the total flock, 76.4% were females of which 58.8% were breeding ewes with at least one PPI and 31.6% were old ewes with four PPI and above. This higher proportion of old breeding ewes indicates that farmers in the study area maintain breeding ewes for long periods of time and the importance of culling is not fully recognized. Males and castrates constitute 21.8% and 1.8%, respectively. More than 92% of the non-castrated males and 32% of the castrates still had only milk teeth. The present study is in close agreement with the CSA (2006) report obtained in the Amhara region with 74.1% females and 25.9% males from the total flock. Sisay (2002), who studied sheep flocks under the traditional systems in Amhara region reported similar results of 76.39% females and 23.61% males.

Linear body measurements

The least squares means of body measurements of Washera sheep are presented in Table 2. The overall least squares mean of body weight, wither height, body length, heart girth, pelvic width and ear length obtained were 26.7±0.45 kg, 69.0±0.36 cm, 57.7±0.33 cm, 74.3±0.49 cm, 14.3±0.12 cm and 9.73±0.08 cm, respectively.

The overall least squares mean of body weight (26.7±0.45 kg) obtained was smaller than that reported for mature western highland sheep (Sisay 2002) while it was in close agreement with Horro and Menz sheep at 12 and 24 months of age (Tibbo et al 2004). Fixed effects district, sex and dentition were a significant (P<0.001) source of variation for body weights. Sheep from Quarit, male sheep and old aged sheep were superior in weight than Yilmanadensa sheep, female sheep and young aged sheep (with dentition <2 PPI), respectively. The effect of district may be because of the differences in the management of sheep between the districts. The superiority in the weight of males over females could be a result of the hormonal differences in their endocrinological and physiological functions (Ebangi et al 1996). Tibbo et al (2004) had also reported the effect of sex on the weight of Horro and Menz sheep. The interaction effect of sex with dentition (P<0.01) affected body weight; male and old aged (dentition 2, 3, 4) sheep were heavier than other groups of sheep. 

Height at wither (69.0±0.36 cm) was (P<0.001) affected by district, sex, dentition and the interaction between sex and dentition. Yilmanadensa sheep were superior in height at wither over their Quarit counterparts. Males with dentition above 1 PPI were taller than other sex and dentition groups. This might be because growth continues to a certain age until bone growth stops. The value obtained is comparable with the value reported for mature western highland sheep (Sisay 2002). However it is greater than that of Horro and Menz sheep at 12 and 24 months of age (Tibbo et al 2004). 

Sex, dentition and the interaction effect of sex with dentition were important sources of variation in body length. Females and sheep with dentition 0 were shorter (P<0.05) in body length than males and sheep with higher dentition groups.

Sheep at Quarit were superior (P<0.01) in heart girth than Yilmanadensa sheep. Sex also affected heart girth that males had higher (P<0.01) heart girth than their female counterparts. With respect to the effect of age, sheep with dentition 4 were superior (P<0.001) over their dentition 0 counterparts. Similarly, there was an interaction effect of sex with dentition (P<0.001); females with four PPI and males with four, three and two PPI were superior over other sex and dentition interaction groups.

Pelvic width also was variable among districts. Quarit sheep had wider (P<0.001) pelvis than Yilmanadensa sheep. Dentition group influenced pelvic width; pelvic width increased with age of sheep.

Prediction of weight using body measurements

The Pearson's correlation of linear body measurements with weight and with each other is presented in Table 3. The observed positive (P<0.01) correlations between weight and other body measurements were in agreement with literature (Varade and Ali 1999; Kassahun 2000; Thiruvenkadan 2005; Afolayan et al 2006; Sowande and Sobola 2007; Khan et al 2006).

Among the body measurements heart girth had the highest correlation coefficient with weight at all dentition groups. The correlation coefficient between weight and heart girth was highest at dentition group 0 PPI. Similarly the highest correlation between weight and wither height, body length and pelvic width was found at dentition group 0 PPI.

The high correlation coefficients observed between body weight and heart girth for all dentition groups suggest that heart girth alone or in combination with other body measurements could provide a good estimate of predicting live weight of Washera sheep at different dentition groups.

Parameter estimates of linear and multiple linear regression equations predicting live weight from body measurements of Washera sheep are presented in Table 4.  In this study, all the fitted equations were good at estimating weight from body measurements (R² of 0.58 to 0.82). Heart girth alone was better in estimating weight (R² of 0.58 to 0.73). Kassahun (2000) found out that heart girth alone explains 83% and 81% of weight of Menz and Horro ram lambs. The higher association of body weight with heart girth was possibly due to relatively larger contribution in body weight by heart girth (Thiruvenkadan 2005).

The highest coefficient of determination (0.82) was obtained when the equations were fitted for the pool (for all dentition groups). Comparing for dentition groups, the highest coefficient of determination was depicted at age group 0 (75.9% of the variation in weight was explained by the equation). The differences in the coefficient of determination of equations between different dentition groups indicated that weight can be estimated using different equations for different age groups with different accuracies. Kassahun (2000) and Alade et al (2008) has estimated different fitted models for different age groups. Within dentition groups, the coefficient of determination (it increases) revealed that weight was better predicted when two or more measurements were included in the equation.

Conclusions 

• The agricultural production system in the study area is mixed crop-livestock which complement each other in such a way that livestock are used as a source for draft and manure for crop production and from crop production the crop residues, straws and stubble serve as main components of livestock feeds in the study areas. Due to the increasing attention given to sheep production, because of the decreasing grazing land as a result of increasing population pressure, land slide and gully erosion and because of their suitability to produce and reproduce under feed shortage and the current increasing market value, production problems identified needs to be improved.  Traditional management practices such as the weaning, docking and use of traditional herbal medications need to be encouraged and supported by scientific knowledge. Flock composition identified is with in the range of many studies in Ethiopia. The higher proportion of old breeding ewes in the flock indicates that farmers in study area maintain breeding ewes for long period of time and the importance of culling.

  
  

• The fixed effects of district, sex, dentition and the interaction between sex and dentition were sources of variation for the most of the response variables (linear body measurements). The high correlation coefficients observed between body weight and heart girth for all dentition groups suggest that heart girth alone or in combination with other body measurements could provide a good estimate of predicting live weight of Washera sheep at different dentition groups. The differences in the coefficient of determination of the equations fitted between different dentition groups indicated that weight can be estimated using different equations for different age groups with different accuracies. For ease of use and higher coefficient of determination, equations fitted for the pool (all age groups) or heart girth alone could be used in the field.

Acknowledgment 

The field research was fully financed by the Amhara Regional Agricultural Research Institute (ARARI) in Ethiopia. The International Livestock Research Institute (ILRI) provided a graduate fellowship to the first author while undertaking his MSc research thesis. The authors are greatly indebted to Mr Zerihun Taddese (ILRI) for his meticulous biometrics support during the data analyses. We are grateful to the staff of Andassa Research Centre of ARARI, particularly to Mr Asresu Yitayew and Mr Habtemariam Assefa for their interest in our research and support during the field work.

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Received 6 July 2010; Accepted 19 July 2010; Published 1 September 2010

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