26 January 1996

Heavier the weight, the less profit

MOST producers taking intensively fed Holstein bulls to over 500kg liveweight will be losing money.

This is evident from a Scottish Agricultural College trial reported by nutritionist Mitch Lewis in Signets latest Beef and Sheep notes.

The work showed that liveweight gains of intensively fed bulls reduced with age.

"Taking animals heavier to 550 to 600kg will secure a big cheque but its easy to forget the cost of producing that heavier carcass. Money will be lost from the 500kg stage onwards," says Dr Lewis.

Holstein bulls at Langhill are bucket reared and offered an ad-lib coarse calf concentrate after weaning at five to six weeks old. At 12 weeks they are transferred to straw-bedded pens and offered a compound nut ad-lib until slaughter at about 470-500kg.

Last year the performance of one batch of 40 bulls going through the system was monitored closely.

Daily gains peaked at a high rate during the two-and-a-half to three-month period when the bulls weighed between 200 and 340kg and then fell. Since performance could be monitored up to a liveweight of about 470kg only, gains for heavier animals were predicted. Daily gains were expected to fall below 1kg at a liveweight of about 580kg (see Fig 1).

Feed intake increased rapidly up to a liveweight of about 300kg and then started to level off. Predicted intakes showed little increase from 500kg onwards, reflecting reducing gains at these heavier weights.

As expected FCR values were low (high efficiency) during the period when the bulls are young and growing rapidly.

Over about 300kg lwt the decline in daily gains, coupled with an increase in maintenance requirements as the bulls became heavier, reduced FCR.

Dr Lewis suggests these results provide a useful guide to help decide on the optimum weight for slaughtering this type of animal. For example, when feed costs £135/t and the return on finished bulls 120p/kg lwt then the break-even point – when daily feed cost equals the value of the daily gain produced – occurs at a liveweight of about 500kg. If interest charges (currently around 15p/head/day) are also taken into account then the point at which the bulls start losing money occurs at an even lighter weight, he says.