Ethiopia has 53.4 million cattle, 25.5 million sheep and 22.7 million goats. These numbers illustrate a considerable potential for the leather industry in the country (Central Statistical Authority [CSA] 2011/2012). With an expected off-take rate of 33%, 35% and 7% for sheep, goats and cattle, respectively, Ethiopia is capable of supplying 16–18 million hides and skins per annum (Abadi 2000; Ethiopian Sheep and Goat Productivity Improvement Program [ESGPIP] 2009; Ministry of Agriculture and Rural Development 2008). The sheep skins have a fine grain and compact structure and goat skins are well known for their quality and international acceptance for producing various leather products.

Skins and hides are the most valuable export item for the country other than coffee (Engineering Capacity Building Program 2009), with export earnings for the country ranging from $405 to $590 million between 1998 and 2004 (Ayele et al. 2003; Tadesse 2005). The leather industry is one of the fastest-growing economic sectors in Ethiopia (Abadi 2000; Bayou 2007). The 26 operational tanneries in the country have a soaking capacity for 153 650 sheep and goat skins and 9725 cattle hides per day (United Nations Industrial Development Organization [UNIDO] 2008). However, they are not working to full capacity, as the hides and skins become available only when meat is needed and are not supplied for sustained leather processing (Bisrat 2013).

The leather industry processes raw hides and skins and produces semi-processed and finished leather both for export and for local markets (Abadi 2000). The semi-processed products are pickled sheep skin, wet blue goat skin and wet blue hides. Pickling refers to treating unhaired, limed, delimed and bated hides or skins with a solution of salt and acid (e.g. sulphuric acid or formic acid) to preserve them or prepare them for the tanning process. Wet blue skins or hides refer to products that have been chrome tanned but not dried (Quality Standard Authority of Ethiopia 2008).

However, the sector faces several challenges. Large numbers of hides and skins are discarded or their quality is substantially reduced by factors that can be avoided. Some of these factors are inherent to the production structure and animal husbandry practices, whereas others arise from the dispersal of the slaughter facilities, unfavourable marketing structures, poor handling (e.g. presentation and transportation) of the raw stock, and insufficient collection and preparation for further processing and export.

Defects are generally classified as pre-slaughter, slaughter, and post-slaughter defects (Leach 2002). The pre-slaughter defects include cockle (ekek), which is due to an allergic skin hypersensitivity reaction to parasitic infestation, grain scratches, pox lesions, warts, tick damage, branding, age (shrinkage) and poor substance (thickness of the skin or hide, toughness of the fibres and the closeness of the texture of the fibres). The major slaughter defects are flay cuts (scores), holes (a complete perforation of the skin or hide resulting from a knife or flaying appliance), poor pattern (an asymmetric skin or hide due to bad opening cuts or distortion during drying because of uneven tension), and vein marks (traces of blood vessels in the skin where the blood was not completely drained). Post-slaughter defects include heating or putrefaction (bacterial and enzymatic breakdown due to improper curing), hide beetle damage, machine damage and grain crack (ESGPIP 2009; Quality Standard Authority of Ethiopia 2008).

Another aspect in the recognition of the defects is that the quality of the hides and skins is seen only after additional costs have been incurred for the removal of hair or wool or when the tanning process has been completed. Raw hides and skins of high grades subsequently have to be rejected or downgraded (Kidanu 2001). In realising the development potential and economic importance of hides and skins, the government of Ethiopia has launched various development programmes aimed at increasing the supply and improving the quality of the raw material. The sector is, however, still constrained by poor quality of raw materials, lack of an efficient marketing structure, weak extension services, competition from local or rural tanning practices and a lack of price incentive for the production of good-quality raw materials (Yacob 2013).

According to the CSA (2011/2012), the Tigray region has 3.5 million head of cattle, 2.9 million goats and 1.1 million sheep. Despite the availability of substantial resources and active attempts to improve animal husbandry and health management, the leather sector contributes only marginally to the national economy so far. This is mainly due to the presence of livestock disease and difficulties to meet the strict international health and trade requirements set by the World Organisation for Animal Health (OIE) (CSA 2011/2012). Detailed information on the major causes of defects in hides and skins is urgently needed to design and implement a cost-effective and sound animal disease control strategy. The objectives of this study were to identify the major defect types in skins and hides and to determine their prevalence in pickled hides and skins of sheep and wet blue goat skins and hides at the Sheba Tannery and Leather Industry in Tigray, northern Ethiopia.

The defects resulting in hides or skins being downgraded or rejected at the study site were classified as pre-slaughter, slaughter and post-slaughter defects.

The major pre-slaughter defects in pickled sheep skins (Table 1) were cockle (68.0%), scratches (67.2%), scars (11.05%) and poor substance (9.8%). The major slaughter defects were flay cuts or scores (11.1%), holes (6.7%) and poor pattern (0.5%). The most prominent post-slaughter defect in pickled sheep skins was heat damage or putrefaction (3.7%).

The major pre-slaughter defects of wet blue salted and dry goat skins (Table 2) were scratches (59.1%) and pox lesions (10.8%), whereas slaughter defects included flay cuts and scores (28.7%), holes (5.6%) and poor pattern (3.7%).Post-slaughter defects observed in both wet blue salted and dry goat skins were putrefaction and machine damage. Grain cracks (49.1%) and hide beetle damage (25.2%) were observed only in dry goat skins.

The major pre-slaughter defects seen in wet blue hides (Table 3) were caused by grain scratches (79.4%), scars (66.1%), branding (28.8%), tick-bite damage (22.7%), age or shrinkage (12.5%), and lumpy skin disease (LSD) (8.3%). The slaughter defects of hides included flay cuts or scores (22.8%), holes (17.5%) and vein marks (11.5%). Putrefaction (21.8%) and hide beetle damage (4.6%) were the only post-slaughter defects seen on hides.

The production of good-quality leather depends on the quality of raw stock. Defects in leather are costly from a production point of view and greatly reduce the sale value of the leather. Damage and defects can occur from birth to the completion of the leather processing (Leach & Wilson 2009). The common pre-slaughter defects seen in pickled sheep skins, wet blue goat skins and wet blue hides in this study included scratches, cockle (ekek), poor substance, brandings, and wounds and scars resulting from pox, LSD or tick infestations. These observations are in agreement with those of a study by Kidanu (2001). However, Tadesse and Mebrahitu (2010) reported a lower percentage of scratches, cockle and scars on pickled sheep skins and wet blue goat skins as the major pre-slaughter defects in the Sheba tannery. Similarly, Mulugeta (2008) reported lower rates of scratches, cockle and scars on pickled sheep skins and wet blue hides. In contrast, Ermias (2000) and Tefera and Abebe (2007) reported much higher presence of cockle on pickled sheep skins from the Sebeta and Dessie tanneries. Bisrat (2013) indicated that the occurrence of cockle was higher in sheep than in cattle and goats. This difference may be due to the variation in veterinary interventions in different districts, which may not be effective against the cockle-causing ectoparasites (especially lice and keds) in the study area.

Pox and LSD lesions were observed on wet blue goat skins, wet blue hides and pickled sheep skins. The animals infected by pox or the LSD virus develop blisters with small red spots, followed by the appearance of papules, vesicles, pustules and pox lesions, or deep, yellow, pea-sized oval ulcers that cause permanent scarring (Boden 2005). According to a report by ESGPIP (2009) and a study by Mulugeta (2008) pox and LSD lesions were also seen on wet blue goat skins, wet blue hides and pickled sheep skins. However, Ermias (2000) and Tefera and Abebe (2007) reported low rates of pox and LSD, which could be attributed to agro-ecological differences. Defects due to brand markings were more common on wet blue hides than on wet blue goat skins and pickled sheep skins. Tadesse (2005) also reported similar findings. Tick damage was observed only in wet blue hides, which is in agreement with the findings of Hagos, Yacob and Mulugeta (2013). The absence of tick lesions in skins could be due to effective ectoparasite control in small ruminants.

The major slaughter defects found in this study were flay cuts or scores, holes, poor pattern and vein markings. Flay cuts and scores are caused by the careless use of a knife during skinning of the carcass because of poor technique (ESGPIP 2009). This was more common on wet blue goat skins than on wet blue hides and pickled sheep skins. This finding is in agreement with previously reported findings (Berhanu et al. 2011; ESGPIP 2009; Yacob 2013). However, Bisrat (2013) found a higher number of flay cut defects in cattle compared with goats and sheep. Wet blue hides presented with holes more often than pickled sheep and goat skins. Similarly, a report by ESGPIP (2009) notes holes as major defects in wet blue hides. Vein marks were observed only in wet blue hides and are caused by incomplete bleeding of the carcass. Blood that remains in the blood vessels leads to the multiplication of bacteria (Yacob 2013).

The post-slaughter defects observed in this study included grain crack, hide beetle damage, and putrefaction, heat or machine defects. Similar post-slaughter defects in hides and skins have been reported previously (ESGPIP 2009). Grain crack was observed only in wet blue goat skins. Grain crack refers to broken fibres on the grain side of hides and skins that were dried before folding. Defects due to hide beetle damage were found in wet blue goat skins and wet blue hides, which is in agreement with the findings reported by Bisrat (2013). Putrefaction was more common in hides than in wet blue goat and sheep skins. This finding was not in line with the report of Yacob (2013). Most of the post-slaughter defects are due to improper curing or preservation and storage of hides and skins.

The mentioned defects lead to downgrading or rejection of skins and hides. In this study, a large proportion of wet blue hides were found to be rejected, followed by pickled sheep skins and wet blue goat skins (Table 4). At the Sheba tannery, cockle led to a financial loss of close to $800 000, with a further loss of close to $250 000 due to rejection of pickled sheep and wet blue goat skins in 2010 (Hagos et al. 2013). The estimated financial losses caused by defects stem mainly from the purchase of raw skins or hides that are of undetectable inferior quality, the cost of processing these skins or hides and the eventual downgrading of such skins or hides, thereby rendering them unsuitable for sale in export markets (Bayou 2005). Berhanu et al. (2011) documented that the major defects leading to skin rejection at the Modjo tannery were cockle and scratches, goat pox, poor substance, scars, and technical defects such as heat and knife cuts.

It is not realistic to expect animal hides or skins to be perfect and defects are almost always present to some extent. Such defects cause depreciation in the value of the hides and skins and the consequence is that farmers, traders and the tanning industry suffer considerable financial losses. We found pre-slaughter defects to be more common than slaughter and post-slaughter defects combined. To improve the quality of hides and skins, animal health service delivery needs to be strengthened and there is a need for effective strategic planning, monitoring and assessment of disease control programmes. Awareness creation, training, and increased collaboration between the Bureau of Agriculture, international and regional organisations, research institutions and the Ethiopian leather associations can address unnecessary losses in the leather industry.