At the recent CAFRE Greenmount Centenary Beef Conference held in conjunction with AFBI and AgriSearch Norman Weatherup stressed the importance of selecting bulls on Estimated Breeding Values (EBV).

Speakers at Enniskillen Beef Conference.

Many producers buy a bull on looks alone and this allows for some assessment of locomotion, length, soundness, condition etc.  However, it is impossible to tell by looks alone:

  • How easily his calves will be born
  • How quickly they will grow
  • Whether his progeny will be lean or fat
  • How milky his daughters will be
  •  How fertile his daughters will be

These characteristics are determined by his genetics and the tools to measure genetics have been around for some time in the form of Estimated Breeding Values (EBVs).

There are two genetic evaluation systems in use in the UK, namely Breedplan and Signet.  Both systems show a bar chart deviating from a vertical central line which is the current breed average.  Anything to the right is better – the further to the right the higher the EBV.  Anything to the left is worse than breed average.

There are four vital EBV’s to be checked in a bull to produce replacement heifers, namely;

 Milk – to ensure a heifer will have sufficient milk to rear a calf.

Calving ease direct – a dead calf will never make a replacement heifer.

Calving ease daughters - to ensure that a bull’s daughters will give birth to their progeny easily.

Scrotal circumference – to ensure that a bull’s daughters will be more fertile and will reach puberty earlier.

Other traits that should also assessed are:

Eye muscle area – 50% of the bull’s progeny will be male so it is important that they meet market specification.  On the other hand, excessively muscled females tend to have poorer fertility and increased calving difficulty. 

Growth – again moderate rather than extreme values are desirable so that progeny reach market specification without increasing the mature weight of the herd which increases maintenance and reduced efficiency.

Fat depth – in some cases it may be desirable to have more fat (although this will appear on the left hand or undesirable side of the graph).  Ideally a suckler cow should gain condition cheaply at grass and lose some condition in the winter months.  Very lean animals may not be capable of this.

EBVs to check in a bull to mate with replacement heifers are calving ease direct, birth weight and gestation length.

It should be noted that calving ease figures for a young bull will be based on the mid-point of his parent’s EBVs.  This means that his figures may change over time as more performance data from his relatives and progeny become available.  However, if a young bull is purchased by a commercial farmer, it is unlikely there will be any progeny information available and the potential for his calving ease figures to change is reduced.  On the other hand an older bull that has been widely used for AI and has sired many calves will have a calving ease EBV with a high accuracy, i.e. unlikely to change.  Therefore, if calving ease is a really high priority, an older, widely used AI bull with proven calving ease is more likely to be a suitable choice than gambling on a young bull.

EBV’s to be checked in a bull to produce slaughter stock:

Calving ease direct – a dead calf can never be sold

Carcase weight – higher values means a heavier carcase

200 and 400 day weight – higher values mean faster growing animals

Eye muscle area / muscle depth – higher values means increased muscularity

Fat depth – select higher values for crossing with lean type cows and vice versa.

Summary

  •  Select a bull based to mate with replacement heifers based on calving ease, birth weight and gestation length EBVs
  • Select a bull to produce replacement heifers based on EBVs for milk, calving ease daughters, scrotal circumference and calving ease direct.
  • Select a bull to produce slaughter stock based on EBVs for carcase traits, fatness and growth.