The Role of Genetics in Optimising MSA Carcase Compliance and Improving MSA Eating Quality

Jake Phillips, Breed Development Officer

Approximately 3.8 million cattle were MSA graded through 39 Australian beef processors, representing 46% of the national adult cattle slaughter in 2019-20.

This is an increase of 3% on the previous year. Historically Grainfed cattle have achieved the best carcase compliance to MSA minimum specifications which include having a pH of less than 5.71 and more Rib Fat than 3mm at the assessment site. During the 2019-20 year, Grainfed cattle achieved a 98% compliance rate to these specifications. The Grassfed cattle presented for MSA grading in 2019-20 improved their compliance rates from the previous year by 1% however still recorded only a 90% compliance rate to the MSA minimum specifications, indicating opportunity for improvement across industry ( Fig1).

Figure 1. The average MSA Non- Compliance to pH and Rib fat for all feed types: Source MSA AO Report 2019-20 Figure 2. The average price premium for MSA compliant cattle in 2019-20 Source: MSA AO Report 2019-20

MSA Price Premiums

Over the past decade the demand for beef that has passed MSA standards has grown exponentially to the stage now that many processing companies and indeed brands of beef offer not only a price premium for these cattle but also a premium for animals with a superior MSA Index eating quality outcome. As reported in the 2019-20 MSA Annual Outcomes Report, an average of $0.27/kg ( Fig2) or $75/ head premium could be achieved over a 279kg carcase, however a recent study of current processing grids suggest a larger price difference with a Southern Australia processor offering $0.30/kg - $.80kg across its MSA compliant grades of cattle and a central NSW processor offering premiums between $0.70/kg - $1.10/kg. These recent premiums from April price grid offerings suggest the per head premium is more likely to be between $200/head and $300/head for over the hooks consigned MSA compliant carcases also meeting the company specific requirements. The 279kg average carcase weight for MSA consigned cattle reported by MLA in 2020 has also recently been projected to be 3% higher during 2021 in their recent industry projections due mainly to improved seasonal conditions and also a reduced turnoff of cattle. The price premiums on offer for cattle producers consigning MSA eligible cattle during 2021 have arguably never been so attractive and consequently the difference between compliance and noncompliance is sparse.

MSA Index underpins Branding

Key parameters regarding cattle management have long been known and continue to be validated by industry regarding the contributing factors to a carcase complying to MSA minimum specifications. More recently there has also been significant research and extension as individual brands create a point of difference around premium eating quality outcomes for their customers. These on farm management strategies have seen widespread adoption of nutrition management, preparing cattle for slaughter techniques and low stress stock handling to maximise the amount of Glycogen stored in the carcase, a critical factor in how the carcase will grade to MSA standards.

A significant factor in achieving improved compliance rates and increased MSA eating quality measured through the MSA index is the use of appropriate genetics and selection within your breeding program. Of the many traits that can impact compliance and eating quality , docility, Rib fat depth and distribution, IMF, Growth and Carcase Weight have the ability to influence the outcome and can be selected for within a breeding program to improve overall profitability for a carcase.

Using Genetics to Optimize MSA Carcase Compliance

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 carcase weight

Using Genetics to Improve your MSA Eating Quality Index

IMF

· Marbling has the largest genetic impact on the MSA

Index outcome · As MSA Marble Score increases by 10, the MSA Index has the potential to increase by 0.15 Index units · E.g. an increase in MSA Marble Score of 100 (roughly equivalent to a 1 unit increase in AUSMEAT marble score) equates to a 1.5 unit increase in MSA Index. · Selection for improved MSA marble score can be achieved by selecting animals with higher Intramuscular Fat (IMF) EBVs · EBVs are estimates of genetic differences between animals in intramuscular fat at the 12/13th rib site in a standard weight steer carcase, with higher IMF EBVs associated with greater marbling in the carcase · For example, an animal with an IMF EBV of +2.9 would be expected to produce progeny with more marbling in a standard carcase than the progeny of an animal with an

IMF EBV of +0.2.

Ossification

· Physiological maturity of the carcase. · Influenced by nutrition, sickness and/or temperament

Ossification scores range from 100 to 590 in increments of 10, with lower scores indicating less physiological maturity. · As ossification score decreases by 10, the MSA Index potentially increases by 0.6 Index units · E.g. A decrease in ossification score of 100 equates to an increase in MSA Index of 6 units. · Younger animals with lower levels of ossification tend to have a higher MSA index values 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 which grow more quickly will reach target live weights at a younger age with lower ossification score. · 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 +60 kg would be expected to produce heavier progeny at 400 days of age than an animal with a 400 Day Weight

EBV of +20 kg

Carcase weight

· Whilst an important specification in most livestock grids, carcase weight only has a small impact on MSA Index, with MSA calculating that as HSCW increases by 1kg, the MSA Index will potentially increase by less than 0.01

Index units. In other words, an increase in HSCW of 100kg equates to an increase in MSA Index of 1 unit. · To select for heavier carcasses at the same maturity (ossification), animals with higher Carcase Weight EBVs should be selected. · Carcase Weight EBVs are estimates of the genetic differences between animals in hot standard carcase weight, with higher Carcase Weight EBVs associated with heavier carcases. · For example, an animal with a Carcase Weight EBV of +60 kg would be expected to produce progeny with heavier carcases than an animal with a Carcase Weight

EBV of +30 kg.