Last year, 16 animals out of 141, or just over 11%, failed to maximise the 20c/kg in-spec bonus payment.

The full 20c/kg in-spec bonus is paid on stock that grade O= or better, and have a carcase fat score of between 2+ to 4=.

Failing to hit this specification, the in-spec bonus reduces to 12c/kg for stock grading O- or having a fat score of 4+.

Stock grading P for conformation results in no in-spec bonus while a fat score of 2- or lower and fat score 5 are also ineligible for any in-spec bonus payment.

Obviously, the cost of falling out of spec reaches far beyond the in-spec bonus payment. It also means the animal slips down the grid payment; -14c/kg was the average price reduction across the entire batch of cattle ranging from 0c/kg to -36c/kg.

In addition, where breed bonuses are available stock will also miss out on this payment in the majority of cases.

This can be worth up to 35c/kg, depending on the breed and time of year you are killing cattle.

Combined, the difference between an in-spec and out-of-spec animal could be worth as much as €130 on the average carcase weight from the demo farm.

The main problem with this is that when purchasing a calf at three weeks old, it is very hard to tell which animal will fail to meet carcase specifications.

Heifers were a bigger culprit than bullocks with 16% failing to maximise the payment, while just 7% of bullocks were penalised. Looking within this, early-maturing breeds were more likely to fall out of spec compared to late-maturing breeds.

The average grade of the Angus and Hereford heifers was just below an O=, while in terms of carcase fat score the average grade was 4- at an average carcase weight of 263kg at just over 19 months of age at slaughter.

Late-maturing breeds

Compare this to the late-maturing breeds of Limousin and Belgian Blue. They graded just below an R- on average at a carcase fat score of 3+ at an average carcase weight of 283kg at just over 20 months old at slaughter.

Of the heifers that were penalised due to having too high a fat score, they were predominantly 4+ but there was also a 5-. This indicates that drafting a week to 10 days earlier would have overcome the problem.

However, the average carcase weight of these heifers was 271kg at just over 19 months of age.

This shows the challenge with this stock type, while trying to maximise carcase weight when slaughtering off grass, we are faced with the prospect of going out of spec at relatively light weights.

Genetics of the cow

Looking at the cow type behind these heifers, as they do account for 50% of the genetics, they are all Holstein Friesian cows with an average EBI, beef sub-index figure of -€16 (national average is -€13) and a maintenance figure, which is really a cow mature size figure of €17.20.

The higher the maintenance figure, the smaller the mature weight of the cow. A maintenance figure of €0 corresponds to a mature cow weight of 640kg.

The average mature weight of these cows is somewhere around 550kg. It is therefore not surprising that we have heifers going over fat at similar weights.