You have to achieve average daily gain from birth of 1.33kg/day — but Dr Norman Weatherup of the College of Agriculture, Food and Rural Enterprise (CAFRE) says this is not a very demanding target for healthy suckler bulls, to produce a finished carcase of 360 kg by 450 days of age (15 months).
The young bull kill in Northern Ireland increased 20% in 2013.
More than half were slaughtered older than 16 months — presenting a problem for the processors because over-age bulls are unsuitable for many premium retail and food service contracts — as their beef is darker, firmer, and drier.
As a result, over-age bull beef price penalties were increased by northern meat processors in the second half of 2013.
A similar trend in the south has left bull beef farmers facing losses.
Finishing suckler bull beef before 16 months with live weight of at least 645kg should start with cow vaccination against scour before calving, and calf vaccination before housing against pneumonia, advised Dr Norman Weatherup.
A milky cow should be able to support a daily gain of 1.3-1.5kg/day in her calf. The key is to use a planned cross breeding programme to produce calves that grow faster.
Early creep feeding is necessary. Adequate fresh leafy grass is needed to maintain cow milk supply to the calf, and calf growth rate after calves start grazing.
For autumn-born bulls, it is vitally important to keep them in stable groups, well away from heifers or cows that could be on heat.
In Northern Ireland, the advice is that bulls be fed at grass from late July or early August, and housed no later than September, for at least 100 days of feeding before slaughter.
While 1.33kg/day is technically not a very demanding growth rate, nonetheless there is no room for a store period in the bull’s life, according to Dr Weatherup. If a bull spends two months on a maintenance-only diet, the required daily gain increases from 1.33 to 1.54kg (which would be challenging for many bulls).
Growth rate and feed conversion ratio will deteriorate after 100 days of feeding in steers and heifers, but bulls have a higher genetic potential for growth and have a lower body fat content, so they maintain growth rates over a longer feeding period.
While steers and heifers can be finished using lower quantities of straight barley, store cattle may be fed maize gluten as the sole concentrate, bulls will be offered concentrates at a much higher rate.
Bull rations require a range of energy, protein and fibre sources to avoid the risk of acidosis, and to maintain a high energy concentration.
It is, of course, possible to finish bulls on a silage-based diet, but the silage must be excellent quality.
It is much easier to manage bulls when they are offered concentrates and straw ad lib, with access to clean, fresh water, (ideally, you should be able to be check water points from outside the pen, at least once per day).