Mid-March-born suckler weanlings should weigh a minimum of 300kg at present to justify keeping them entire in order to meet market specifications for bull beef next spring and early summer.

Finishing male suckler-bred cattle as young bulls under 16 months is an efficient beef production method, offering better feed conversion and lower greenhouse gas emissions than steers.

Weanlings to be finished as bulls should be selected from sires with high growth rates and easy fleshing to ensure adequate fat cover at slaughter.

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In our example, a mid-March-born suckler calf weighing around 43kg at birth and achieving an average daily liveweight gain (DLWG) of 1kg until weaning in mid-November should weigh at least 300kg.

Targeting an average DLWG of 1.5kg/day from weaning to slaughter should see bulls weighing 500kg at 12 months and will give a final liveweight of 680kg at 16 months. Assuming an average kill-out of 58%, this will produce a carcase weight of 395kg.

Silage quality drives margins

Concentrates with a cereal content of 75% to 80% and crude protein of 15% are sufficient for growing bulls up to 12 months of age. The protein can be reduced to 12-13% thereafter.

Bull weanlings provided with high-quality silage of at least 70% D-value should be gradually moved up to 4 to 5kg of concentrate over the next three to four weeks and remain on this until 12 months of age, progressing to 6kg to 8kg thereafter.

However, at silage qualities closer to 60% D-value, much higher rates of concentrate will need to be fed, with 7kg to 8kg required to achieve 1kg DLWG up to 12 months of age, and significantly more after this period.

Bull beef systems based on ad-lib concentrates with poorer D-value silage will be most vulnerable to changes in beef and concentrate prices, given that the total amount fed could be up to 700kg more per head.

Management

Initial space allocation needs to be based on the target final finished weight of bulls in the pen.

Ideally, bulls should be housed in pens away from breeding stock and finishing heifers.