The effect of breed type and feeding system on yields of edible and saleable components of Somali and Arsi-Bale goats

G Legesse^1,2 and G Abebe²

¹University of Hohenheim, Institute of Animal Production in the Tropics and Subtropics (480a), 70593 Stuttgart, Germany
getahun@uni-hohenheim.de
²University of Hawassa, Awassa College of Agriculture, Department of Animal and Range Sciences, P. O. Box - 05, Awassa, Ethiopia
gabebe7@yahoo.com
 

Abstract 

The slaughter data from 27 Arsi-Bale and 21 Somali intact male goats managed under three feeding systems (viz. intensive, semi-intensive and extensive) were analyzed to determine the influence of genotype and feeding system on the edible and saleable components. Edible proportion of live weight was obtained as all body components minus pelt, respiratory tract, heart, head, feet and gut content while saleable proportion of live weight was defined as all body components except feet and gut content.

According to local criteria, the total edible and saleable percentages were 60.2 and 77.5 for Somali and 62.1 and 80.8 for Arsi-Bale goats, respectively. Arsi-Bale goats had significantly higher (P<0.05) edible and saleable live weights than Somali goats. Animals managed under the intensive and semi-intensive feeding systems had statistically higher (P<0.05) edible and saleable proportions of live weight than the extensively managed animals. Though breed did not exert significant influence (P>0.05) on both external and internal non-carcass components, animals managed extensively had higher (P<0.05) external non-carcass components as a proportion of empty body weight than the animals managed under the other two feeding systems. The higher proportion of external non-carcass components that are inedible under Ethiopian condition was the primary cause of the lower edible proportion of extensively managed animals. Significantly (P<0.05) higher total fat were dissected in the Somali than in the Arsi-Bale that may indicate their adaptation to their area of origin that has been facing seasonal feed-supply fluctuations.

Key words: carcass, Ethiopia, extensive, intensive, non-carcass components, semi-intensive

Introduction

Goat meat is consumed in most regions of Ethiopia mainly during holidays and feasts. The rise in demand and price of goat meat is indicated in the country (Woldu et al 2004). In many parts of the country, non-carcass items like blood, liver and rumen are also important. Butcheries specializing in goat meat sale and hotels serving food made exclusively from goat meat have been mushrooming in major urban areas in recent years. It is not uncommon to find dishes made from intestines, rumen, liver etc in those growing number of shops and hotels. Some non-carcass components like blood are also delicacy in most pastoral and other communities. Much of the research on meat production on small ruminants focus only on carcass yield and quality and ignored valuable components of traditional meat consumption. In most meat breed evaluation studies non-conventional edible parameters are often not measured thus leading to reporting of dressing percentage only. Recent reports highlighted the need to consider the total yield of consumable and saleable products rather than only carcass weight and dressing percentage in evaluating the suitability of breeds for meat production (Ermias et al 2000; Shrestha and Fahmy 2005). This study, therefore, aimed at evaluating the influence of genotype and feeding system on the edible and saleable components of Ethiopian goats.

Methodology 

Forty-eight intact male goats (27 of Arsi-Bale and 21 Somali), approximately 9 months of age, were managed under three feeding systems (viz. intensive, semi-intensive and extensive) for a period of three months at the Research and Farm Center of Awassa College of Agriculture, Ethiopia

Goats on the intensive feeding system were housed individually and consumed coarsely chopped Rhodes-grass (Chloris gayana) hay ad libitum supplemented with 300 g/day of a concentrate mixture (54% wheat bran, 19% Noug (Guizotia abyssinica) cake, 26% maize, and 1% salt). Goats on the semi-intensive feeding system grazed a grass pasture for 7 h daily and were also supplemented with 300 g/day of the concentrate mixture. Goats on the extensive feeding system grazed the same pasture for 8 h/day. When not grazing, semi-intensive and extensive goats were housed in a confinement facility.

At the end of the experiment, animals were fasted for 16 hours before harvest but had access to water. Body weight was determined immediately before slaughter. Weights of the blood, skin, head, feet, and hot carcass were determined. Different segments of the gastrointestinal tract were weighed with and without digesta; empty body weight was determined as the difference between slaughter and total digesta weight. Fat surrounding the stomach, intestines, and kidney was separated and weighed, and weights of the heart, liver, kidneys, and respiratory tract (trachea and lungs) were determined. Weights of external non-carcass components (head, pelt, and feet) and internal non-carcass components (blood, visceral fat, empty gut, liver, respiratory tract with lungs, spleen and heart) were expressed as a percentage of Empty Body Weight (EBW). Based on the actual condition in most parts of Ethiopia, edible proportion of live weight was obtained as all body components minus pelt, respiratory tract, heart, head, feet and gut content. Saleable proportion of live weight was defined as all body components except feet and gut content. Saleable products are marketable parts of a slaughtered animal that include pelt and parts used either for human consumption or as food for pet animals. Some body parts, like lung, are not commonly used for human consumption in most urban areas but can be sold with lower price to feed pet animals.

Data were analyzed using General Linear Model procedure of SAS (1994) as a two-by-three factorial arrangement of treatments. Genotype × feeding system interactions were not significant (P > 0.05); hence, the interaction was dropped from the model 
 

Results and discussion 

The edible proportion of live weight of Somali and Arsi-Bale goats are presented in Table 1. The total edible material according to local criteria was 60.2 and 62.1% for Somali and Arsi-Bale, respectively. The total saleable percentages were 77.5 and 80.8 for Somali and Arsi-Bale goats, respectively. Arsi-Bale goats had higher (P<0.05) edible and saleable live weights than Somali goats.

Previous analysis indicated that body components such as feet, empty gut, liver, respiratory tract, kidney and spleen were heavier (P<0.05) in Somali goats (Legesse et al 2006). However, when non-carcass components are expressed as proportion of EBW, Arsi-Bale goats had significantly (P<0.05) higher values.

In indigenous East African goats slaughtered at approximately 14 kg live weight, Wilson (1958) estimated that the total edible proportion of the live weight according to local criteria was 48% of the live weight while the total saleable percentage of different age groups fell between the range of 55% to 61%. For Malaysian goats slaughtered at about 25 kg live weight, Devendra (1966) reported a higher (61%) total edible material. According to local criteria in Malawi, the edible proportion of the local goats of 19.4 kg live weight was as much as 76% (Owen 1975). On the other hand, Owen and Norman (1977) reported 78 to 81% of saleable and 70 to 74 of edible percentages for indigenous Malawi goats and Boer goats. Mahgoub and Lodge (1996) also found 62 to 63 total edible and 69 to 71 total saleable percentages for different sex groups of Omani Batina goats slaughtered at 28 kg. Most of the edible and saleable percentages reported in other parts of tropics are comparable with those computed in the present study.

There were no breed differences (P>0.05) for both external and internal non-carcass components. However, as it is presented in Table 1, animals managed extensively had higher (P<0.05) external non-carcass components as a proportion of empty body weight than the animals managed under the other two feeding systems. Conversely, animals managed under the intensive and semi-intensive feeding systems had significantly higher (P<0.05) edible and saleable proportions of live weight than the extensively managed animals. This lower edible proportion of extensively managed animals was primarily due to their higher proportion of external non-carcass components that are inedible under Ethiopian condition. In addition to its effect in carcass components, feeding system was found to affect non-carcass components (Legesse et al 2006) thereby the saleable and edible percentages of the animals that may possibly have an effect on the profitability of the systems (Legesse et al 2005). The extensively managed goats had proportionally heavier (P<0.05) head, empty gut and respiratory tract than both semi-intensively and intensively managed animals. But, most of the actual values of non-carcass components for animals managed under the other two systems were significantly heavier (P<0.05) than the animals kept extensively (Legesse et al 2006).

The gut contents in Somali and Arsi-Bale goats comprise about 18% and 15% of live weight, respectively. The gut contents proportion of Somali goats is significantly higher (P<0.05) than that of Arsi-Bale. The gut fill values as a proportion of live weights obtained for both indigenous goat breeds studied were greater than the six to eight percent recorded for finished Sudan Desert goats (Gaili et al 1972) but fall within the range of ten to twenty three reported in Zimbabwe for Matabele goats (Hatendi et al 1992) and comparable with fifteen to eighteen reported for indigenous Malawi and Boer goats (Owen and Norman 1977). 

The least squares means of carcass and non-carcass fat depots expressed as a percentage of empty body weight are presented in Table 2. The percentages of omental-mesentric fat, kidney fat, carcass fat and total body fat determined by dissection were 0.73, 0.39, 6.53 and 7.64%, respectively, in the Somali and 1.02, 0.54, 5.13 and 6.70%, respectively, in the Arsi-Bale. Significantly (P<0.05) higher carcass and total fat were dissected in the Somali than in the Arsi-Bale. Omental-mesentric fat and kidney fat proportions (as a percentage of empty body weight) were significantly (P<0.05) lower in goats under extensive management than the other groups. The total non-carcass and total body fat proportions of the animals under intensive system were significantly (P<0.05) higher than those managed under both extensive and semi-intensive systems. Somali goats are mainly distributed in semi-arid and arid areas of the country where seasonal scarcity of feedstuffs has been prevalent. The higher proportion of total body fat relative to the Arsi-Bale goats may possibly one of the adaptation mechanisms to the prevailing condition.

References 

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Received 1 March 2008; Accepted 2 April 2008; Published 10 June 2008

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