The meaning of lamb carcass quality depends on the geographic area. The amount of fat appreciated by the consumer, for example, is different in various culinary traditions. In fact, in the less developed countries is appreciated an higher amount of fat if compared to the developed ones. In many countries (e.g. Africa, South America), they prefer to slaughter animals more than one year old and with higher live weights (30-50 kg) (Rubino et al., 1999). In developed countries the quality of ovine carcasses is evaluated according to some enstabilished standard. In USA the American Sheep Industries (ASI) association revisited this standards many times: the last version became effective on July 6, 1992. These standars for grades of lamb, yearling mutton and mutton, are written primarily in term of carcasses. However, they also are applicable to the grading of sides. Ovine carcasses are classified as lamb (until 12 months of age), yearling mutton (12-15 months of age), or mutton (over the 24 months), depending upon their evidences of maturity as indicated by the development of their muscular and skeletal systems (Field et al., 1990).
The official USDA grade standards for lamb carcasses, use a dual grading system of quality grades and yield grades. If a processor wishes to have lamb carcasses
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graded, both a quality and yield grade must be applied to each carcass. Quality grades are intended to sort carcasses on eating quality, and as an indicator of intramuscular fat (marbling) is the major determinant of quality grade. The quality grades for lamb are Prime, Choice, Good, Utility and Cull. Prime indicates the highest degree of marbling and eating quality and Cull indicates the lowest degree of marbling and eating quality.
Yield grades are intended to sort carcasses on proportion of lean meat in the carcass, and the only measurement used to determine yield grade is subcutaneous fat thickness midway over the loin eye between the 12th and 13th rib. Yield grades for lamb are YG1, YG2, YG3, YG4, and YG5. YG1 indicates the highest and YG5 indicates the lowest proportion of lean meat. Yield grades are calculated by the following formula:
Yield grade = 0.4 + (10 x fat thickness, in.). For example, a carcass with a fat thickness of 0.27 has a calculated yield grade of 3.1 (0.4 + (10 x .27)), and is a USDA YG3 carcass. Carcasses with calculated yield grades of 3.0 to 3.9 are USDA YG3 carcasses.
Table 2.2 presents the relationships between fat thickness, calculated yield grade, and USDA yield grade. (Thomas, 2014).
Table 2.2. Fat thickness and USDA yield grades for lambs
Fat thickness, in. Calculated yield gradea USDA yield grade
0.0 - .15 0.0 - .19 YG1
.16 - .25 2.0 – 2.9 YG2
.26 - .35 3.0 – 3.9 YG3
.36 - .45 4.0 – 4.9 YG4
.46 and greater 5.0 and greater YG5
a .4 + (10 x fat thickness)
Carcass classification of ruminants in the European Union is based on the EUROP carcass classification system (Commission Regulation (EEC) No 461/93, 1993;
Council Regulation (EEC) No 2137/92, 1992). The overall aim of the EUROP classification system is to sort carcasses according to their value, for further processing and to ensure fair payment to farmers. The EUROP classification system makes use of four carcass categories or maturity groups of sheep, mutton, yarling mutton, lamb and
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suckling lamb. For ruminants EUROP classification is carried out by humans assessment of conformation and fat class in addition to carcass weight. Conformation class describes carcass shape in term of convex or concave profiles and is intented to indicate the amount of meat in relation with bone, where flesh or meati s regarded as the sum off at and lean. Fat class describes the amount of visible fat (subcutaneous) on the outside of the carcass (Fisher & Heal, 2001). Carcasses are given classes from 1 to 15, where grade 1 is P for conformation class and 1 for fat class. Grade 15 is E+
conformation class and 5+ for fat class. High value for conformation class indicates a carcass with well to excellent rounded muscles. High value on fat class indicates a carcass with a high degree of external fat (sub-cutaneous), and utilizes the relationship between external fat and total fat content of carcasses. Classification of ruminant carcasses is traditionally done by trained assessors. The approval limits for certification and validation of assessors for the EUROP classification system are described by the EU Commission regulation (EC) No. 1215/2003. (rewieved by Johansen et al., 2006).
Generally, in lamb the yield grading predicts the amount of sellable product. Meat yield is usually classified in 5 categories grade.
In order to obtain uniform offer of any product on the market, it is necessary to develop legislative system for its classification. Due to mentioned, in production and trade of ovine meat in EU countries, as well as in Croatia, there are legislated classification rules that should be conducted as effectively as possible. Classification of lighter carcasses (< 13 kg) is based on three factors: slaughter weight, meat colour and fat cover. In EU for carcasses lighter than 13 kg there is additionally accepted method for assessment of fat cover with photographic standards. Depending on weight class, colour and fat cover, light carcasses are additionally segregated into two classes. Heavy carcasses (> 13 kg) are classified under ―S.E.U.R.O.P― classification. Compared to Croatia, in classification of carcasses heavier than 13 kg in EU countries, there is additionally considered degree of fat cover. Within EU, each country itself, i.e.
accredited assessors and inspectors are amenable for control of carcass assessments on slaughter lines. In Croatia, the aforementioned classification is accredited by Croatian Agriculture Agency which is under jurisdiction of Ministry of Agriculture. Regarding to current law regulation, classification of lamb and sheep carcasses and pricing in some EU countries as well as in Croatia, is hard to accomplish. Therefore, great efforts are
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made into augmentation and in some cases even substitution of current laws that regulate ovine meat production and trade of ovine meat (reviewed by Kaic et al., 2012).
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