Beef Cattle Carcass Assessments
3.11 Carcass assessments
The ultimate goal of all beef cattle production systems is to efficiently produce a high yield of palatable beef. Meat quality and the quantity of edible portion are basic factors used to assess carcass merit. However, the relative emphasis to be placed on quality and quantity are subject to change with changing market demands.
Not all beef producers need complete carcass data. Careful thought should be given to the specific information that will be useful. Increasing the amount of traits to be recorded on large numbers of carcasses adds to the time required, costs, and likelihood of errors and may reduce beef processors’ interest in cooperating. Only trained personnel should be contracted to do this in the large processing plants. Carcass weight, composition and quality are essential traits to be recorded at the slaughterhouse.
An essential prerequisite for gaining records in the slaughterhouse is that the ID of the live animal stays with the carcass or that a system is used, that allows the reporting carcass data with the ID of the corresponding live animal.
The following traits, as illustrated in table 4, are recommended as mandatory traits for breeding purposes.
3.11.1 Carcass weight
Carcass weights are unaffected by variation in shrinking and therefore – apart from the scaling effect - show less variation than live weights. Compared to live weights they relate more to meat yield and to the consumers endpoint. Calculation of net gain is based on slaughter weight.
Typically, carcass weights are collected by commercial abattoirs; additionally experimental abattoirs come into consideration. Carcass weights should be collected consistently to ensure an informative data analysis.
Usually, carcass weight is defined by appropriate national legislation which clearly specifies which parts of the carcass are to be removed prior to taking the weight.
In the case of no legal definition, carcass weight should be defined as the hot weight of both half carcasses after removal of skin, bled and eviscerated and after removal of external genitalia, the limbs at the carpus and tarsus, head, tail, kidneys and kidney fats and the udder.
Preferably the unit of measurement should be metric to the nearest of 500 grams.
3.11.2 Carcass grade
Carcass grades significantly affect the market value of the carcass. Therefore they form a trait with big economic impact and should be used for the analysis of progeny productivity. Grading mostly is done according to national standards that frequently are based on appropriate legislation.
a. However, according to different market demands, national grading schemes frequently target different objectives and therefore are composed of different traits. On a global level there are two predominant types of grading schemes: b. USDA grading scheme including the following components - Class (steer, bullock, bull, heifer, cow) - Maturity - Meat colour - Texture of lean meat - Quality grade: 8 levels (Prime; Choice; Select; Standard; Commercial; Utility; Cutter; Canner) - Marbling - Firmness - Yield grade - External fat - Kidney, pelvic and heart fat - Ribeye area - Carcass weight c. EU grading scheme including the following components - Class (calf, young bull (=bullock), bull, steer, heifer, cow) - Conformation grade: 6 levels (S-E-U-R-O-P) - Fat grade: 5 levels (1-2-3-4-5) As a consequence meat reports are almost incomparable across big market regions like e.g. North America, Europe and other continents. Therefore the grading system should be clearly indicated on reports provided for use outside the country where the grading scheme is applied. In order to provide useful information that might be used outside the market region, it is recommended additionally to record each of natural components forming the grade. 3.11.3 Dressing percentage Dressing percentage describes the percent ratio between carcass weight and the live weight taken immediately before slaughter. Although dressing percentage mainly is used for the estimation of carcass weights of live animals, it provides additional information on the animal’s type even if carcass weight is measured directly. A scale that measures in increments of 1 kg or 2 lb., or less, should be used for taking the live weight immediately before slaughter. As live weight is largely influenced by shrinking, dressing percentage should account for this effect, by standardisation of the live weight to 12-hours shrinking time. The correction factors should apply in the special production environment of the animals. Dressing percentage should be described as percentage with 1 decimal place. 3.11.4 Meat yield Meat yield means the percentage of lean meat in the beef carcass as obtained by dissection. However, - with regard to high costs arising from carcass dissection - meat yield frequently is estimated on the base of surrogate traits, that can be easily measured in the course of the slaughter process. In some areas meat yield refers to the whole lean meat contained in the carcass, whereas other regions account for specified retail cuts forming the most evident part of the carcass value. Meat yield should be described as percentage with 1 decimal place. Some areas apply yield grades rather than meat yield itself; e.g. the USDA yield grade is a numerical score from 1 to 5 expressed as a whole number. It represents the yield of the boneless, closely trimmed retail cuts from the round, loin, rib and chuck. These cuts represent about 75% of the carcass weight and about 90% of the carcass value. Y.G.=2.5 + (2.5 X adjusted fat thickness, in inches) + (0.2 X per cent kidney-, pelvic-, heart fat) + (0.0038 X hot carcass weight, in pounds) - (0.32 X Ribeye area) The relation between yield grade and meat yield is described in table 3.5.
