Reading a Breedplan catalogue

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Introduction

When buying bulls, first ensure that they are sound and fertile, with an acceptable temperament. BREEDPLAN figures can then assist you to check that their genetics will suit your cows, the type of country, and the market.

Areas in which BREEDPLAN can assist include growth rate, milk, fertility, calving ease, carcase predictions and, in some cases, feed efficiency and docility. Other attributes such as structure, eye pigment etc. still need to be assessed by eye.

Estimated breeding values

The basic descriptive units of BREEDPLAN are estimated breeding values (EBVs). These are calculated from:

  • the animal’s own performance (weights, scrotal size and other factors);
  • the performance of relatives (parents, relations and progeny) in all linked herds;
  • other related measurements (for example, yearling weight and weaning weight are genetically linked, so each of these weights contributes to an estimate of the other weight).

Therefore, EBVs are a much better predictor of the performance of a bull’s progeny than single measurements on the bull near sale time (e.g. weight, scrotal size, raw scan measurements).

EBVs are expressed in everyday units, for example:

  • kilograms (kg) for weight
  • centimetres (cm) for scrotal size
  • millimetres (mm) for fat.

The values can be positive (+) or negative (–), depending on whether the value for an animal is under or over the ‘base’, which is constant and set at zero. The current breed average is often a more important benchmark than the base (see Using the catalogue).

GROUP BREEDPLAN

The EBVs given in a catalogue may be either the EBVs within that herd, or the EBVs across the whole breed as in GROUP BREEDPLAN. Most Australian bull breeders are now using GROUP BREEDPLAN. The major breeds now regularly produce sire and dam summaries with GROUP BREEDPLAN EBVs. These are published in booklets and on society websites. For links to participating breeds, see http://breedplan.une.edu.au.

All GROUP BREEDPLAN catalogues should display the appropriate logo, for example:

Breedplan AngusBreedplan LimousinBreedplan HerefordBreedplan Brahman

Using the catalogue

Catalogues vary, but most entries should look something like this:

Breedplan entry

* Accuracy figures (expressed as a percentage) are an indication of how much information has been provided, and hence the ‘reliability’ of each EBV. EBVs of lower accuracy are more likely to change as more information is collected. There is an equal chance of this change being up or down.

The given EBVs are set against a zero base that is held constant. For many breeds the base was set in the 1970s. It is therefore more important to compare EBVs with the breed averages for the year of birth. In this case, 2-year-old bulls for sale in 2003 were born in 2001. In the above example, bull A is above average for all the weights, and average for milk and scrotal size, compared with calves of this breed born in 2001.

Comparing the progeny of bulls A and B

We can now examine in more detail how the progeny of the two bulls A and B (in the above catalogue example) would compare.

  • Birthweight. The birthweight EBV is the best predictor of the birthweight of a bull’s progeny. Bull A is well above the breed average, and when joined to a random group of cows, would produce calves averaging 3 kg heavier than those produced by bull B. (There is a 6 kg difference in birthweight EBVs between the bulls. Half of this, the sire’s contribution, will be expressed in the calves.) Birthweight is by far the most important genetic influence on calving ease. Gestation length, calf shape, and the uterine environment and pelvic area of the cow also influence calving ease, as do many non-genetic factors.
  • Milk. BREEDPLAN partitions weaning weight into the ‘milk’ and ‘growth’ components. The ‘milk’ EBV predicts the milking ability of a bull’s daughters, expressed as the kilograms of extra weaning weight that their calves would have. Bull B is well above breed average and would have the best milking daughters. The difference here would obviously only influence a buying decision when an increase in the level of milk production is a high priority. In some situations, ‘high milk’ is a disadvantage.
  • 400-day and 600-day weights. These EBVs are used to predict weight at various ages, so they are most useful, in turn, for yearling or heavy steer producers. Bull A is ahead in both these areas and would produce, on average, calves heavier by 8 kg and 10 kg as yearlings and steers respectively, than calves produced by bull B. Note: ‘200-day growth’ and ‘Mature cow weight’ EBVs are also available but are not used in this example.
  • Scrotal size (SS). Bull A is marginally below the breed average for scrotal size. Bull B is above average and will breed daughters with earlier puberty and shorter calving intervals, and sons with earlier puberty and bigger scrotal size. (Some breeds also give the female fertility EBV, ‘Days to calving’ (DC).)
  • Carcase traits. Carcase traits include rump fat, eye muscle area (EMA) and intramuscular fat (IMF). Compared with the breed average, bull A will produce earlier finishing or fatter progeny, with below-average muscling and above-average marbling.

Further information

See other Agnotes in this series for further information on BREEDPLAN and EBVs.

About the author

Brian Sundstrom is Cattle Breeding Coordinator with NSW Agriculture. Part of this role involves technical specialist and advisory work with BREEDPLAN from an office at the Agricultural Business Research Institute (ABRI) at Armidale. His other role is with the Beef CRC group.