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Carcase EBV Explained

BREEDPLAN combines both live animal ultrasound scanning information with abattoir chiller carcase data to calculate EBVs that provide information regarding the genetic differences in carcase composition between animals. Carcase EBVs provide a useful tool to assist breeders in targeting animals that meet production and market requirements.

BREEDPLAN currently produces seven Carcase EBVs:

  • Carcase Weight
  • Rib Fat Depth
  • Rump Fat Depth
  • Eye Muscle Area
  • Intramuscular Fat (Marbling)
  • Retail Beef Yield
  • Shear Force

Carcase Weight

Carcase Weight EBVs are estimates of the genetic differences between animals in hot standard carcase weight (as defined by AUSMEAT) at 650 days of age. Carcase Weight EBVs are expressed in kilograms (kg).

Larger, more positive, Carcase Weight EBVs are generally more favourable. For example an animal with a Carcase Weight EBV of +40 kg would be expected to produce progeny with heavier slaughtered carcases at 650 days of age than an animal with a Carcase Weight EBV of +30 kg.

Carcase Weight should not be confused with yield. The Carcase Weight EBV is an indication of the animal’s carcase weight and not an indication of the animal’s yield percentage.

Eye Muscle Area (EMA)

Eye Muscle Area EBVs are estimates of the genetic differences between animals in eye muscle area at 12/13th rib site in a standard weight steer carcase. EMA EBVs are expressed in square centimetres (cm2).

Larger, more positive, EMA EBVs are generally more favourable. For example, a bull with an EMA EBV of +4 cm2 would be expected to produce steer progeny with a greater degree of muscle expression than a bull with an EMA EBV of +1 cm2, relative to carcase weight.

Rib Fat

Rib Fat EBVs are estimates of the genetic differences between animals in fat depth at the 12/13th rib site in a standard weight steer carcase. Rib Fat EBVs are expressed in millimetres (mm).

More positive or more negative Rib Fat EBVs may be more favourable, depending on your breeding goals relating to the finishing ability of your animals. A bull with a Rib Fat EBV of -0.4 mm would be expected to produce leaner calves than a bull with a Rib Fat EBV of +0.4 mm, relative to carcase weight.

Rump Fat

Rump Fat EBVs are estimates of the genetic differences between animals in fat depth at the P8 rump site in a standard weight steer carcase. Rump Fat EBVs are expressed in millimetres (mm).

More positive or more negative Rump Fat EBVs may be more favourable, depending on your breeding goals relating to the finishing ability of your animals. A bull with a Rump Fat EBV of -0.6 mm would be expected to produce leaner calves than a bull with a Rump Fat EBV of +0.6 mm, relative to carcase weight.

Stock with positive fat EBVs are likely to produce progeny that are fatter, or more earlier maturing, on average than stock with lower or negative fat EBVs. Increasing fat depth leads to a decrease in retail beef yield, however most market specifications require a minimum fat depth. Breeders aiming to breed leaner, higher yielding cattle may select for lower fat EBVs. Breeders wishing to finish their animals earlier may tend to select animals with moderate fat EBVs. Caution should be placed on selecting for extremely low fat EBVs for replacement females as this may indicate females that are more difficult to get in calf.

Differences between Rib Fat EBVs and Rump Fat EBVs can indicate differences in fat distribution among animals.

Retail Beef Yield (RBY)

Retail Beef Yield (RBY) EBVs are estimates of genetic differences between animals in boned out retail beef yield in a standard weight steer carcase. RBY EBVs are reported as differences in percentage (%) yield.

Larger, more positive, RBY EBVs are generally more favourable. For example an animal with a RBY EBV of +0.9% would be expected to produce progeny that would yield higher percentages of saleable beef in a standard weight steer carcase than an animal with a RBY EBV of +0.1%.

Intramuscular Fat (IMF)

Intramuscular Fat (IMF) EBVs are estimates of genetic differences between animals in intramuscular fat (marbling) at the 12/13 rib site in a standard weight steer carcase. IMF EBVs are reported as differences in percentage (%) IMF.

Larger, more positive, IMF EBVs are generally more favourable. For example an animal with an IMF EBV of +0.8% would be expected to produce progeny that would express more marbling in a standard weight steer carcase than an animal with an IMF EBV of +0.1%. For markets where marbling is important (eg. Japanese B2/B3 market, restaurant trade, MSA etc.), higher IMF EBVs can contribute significantly to carcase value.

Shear Force

Shear Force EBVs are estimates of genetic differences between animals in meat tenderness. Shear Force EBVs are expressed as differences in the kilograms of shear force that are required to pull a mechanical blade through a piece of cooked meat and are calculated from shear force measurements (i.e. objective abattoir measures of meat tenderness), gene marker information and flight time records.

Lower, more negative, Shear Force EBVs are more favourable. That is, lower EBVs indicate that less shear force is required and hence the meat is more tender. For example, a bull with an EBV of -0.90 would be expected to on average produce progeny with meat that required a shear force of 1 kg less than a bull with an EBV of +1.10.