The role of Genetics in the Quality Beef Equation

Supplied by Angus Australia for AngusPro magazine 2022

Over the past decade the demand for quality beef has grown exponentially, to the stage now that many processing companies, and indeed brands of beef, offer a price premium for these cattle. Let’s take a look at how genetics play a part in optimising your results, in order to meet premium beef program targets here in New Zealand.

Docility
Docility EBVs are estimates of genetic differences in the percentage of an animal’s progeny that will be scored with acceptable temperament, with higher EBVs associated with superior temperament.

• For example, an animal with an EBV of +20 would be expected to, on average, produce a greater percentage of progeny that have acceptable temperament than a bull with an EBV of -2.

Rib Fat and Distribution
• Rib fat thickness is the measured depth of subcutaneous fat over the quartered rib site between the 5th and 13th ribs. A covering of fat is needed to protect the high-value primal cuts from rapid chilling, which can cause toughening, and to enhance eating quality and appearance.

• Selection for adequate rib fat and fat distribution can be achieved by selection of animals with appropriate rib and rump fat EBVs.

• For example, an animal with a Rib Fat EBV of +0.4 mm would be expected to produce calves with more fat than an animal with a Rib Fat EBV of -0.6 mm, relative to carcass weight.

Intramuscular Fat
• Marbling has the largest genetic impact on the premiums currently offered in New Zealand.
Selection for higher premiums can be achieved by selecting animals with higher intramuscular fat (IMF) EBVs.

• EBVs are estimates of genetic differences between animals in IMF at the 12/13th rib site in a standard weight steer carcass, with higher IMF EBVs associated with greater marbling in the carcass.

• For example, an animal with an IMF EBV of +2.9 would be expected to produce progeny with more marbling in a standard carcass than the progeny of an animal with an IMF EBV of +0.2.

Ossification
• Physiological maturity of the carcass.

• Influenced by nutrition, sickness and/or temperament.

• Younger animals with lower levels of ossification tend to have a higher value than older animals with higher ossification values.

• Selection for lower ossification scores can be achieved by selecting animals with higher 200 Day Growth, 400 Day Weight and 600 Day Weight EBVs, as calves that grow more quickly will reach target live weights at a younger age with lower ossification.

• 200 Day Growth EBV, 400 Day Weight EBV and 600 Day Weight EBV estimate the genetic differences between animals in live weight at 200, 400 and 600 days respectively due to an animal’s growth genetics. In all three cases, higher EBVs are associated with heavier weights at the respective age.

• For example, an animal with a 400 Day Weight EBV of +60kg would be expected to produce heavier progeny at 400 days of age than an animal with a 400 Day Weight EBV of +20kg.

Carcass Weight
• In New Zealand you’re currently paid on carcass weight.

• To select for heavier carcasses at the same maturity (ossification), animals with higher Carcass Weight EBVs should be selected.

• Carcass Weight EBVs are estimates of the genetic differences between animals’ carcass weights, with higher Carcass Weight EBVs associated with heavier carcasses.

• For example, an animal with a Carcass Weight EBV of +60kg would be expected to produce progeny with heavier carcasses than an animal with a Carcass Weight EBV of +30kg.

Are There Opportunities to Improve Through Genetic Selection?
A recent Australian study revealed a $695 per carcass difference in carcass revenue (Graph1.) based on carcass data collected in Cohort 5 of the Angus Sire Benchmarking Program (ASBP).

  • The study compared carcass values, on a progeny average basis, between the highest and lowest ranked sires.
  • The parameters are based on a general long-fed production system (200+ days) with the aim of producing and selling high-quality Angus beef products.

Summary
Placing selection pressure on your breeding program and the genetics being utilised with relation to docility, rib and rump fat, IMF, carcass weight and growth will all provide benefits to your overall results with carcass weights and marble scores. A careful and balanced approach will ensure an optimum outcome for your production system and should include a balanced selection of these traits as well as other production traits important to other aspects of your business, such as fertility. Feed and management are important, however genetics need focus for optimum overall results.