Articles


13th October, 2006

SELECTING BULLS FOR YEARLING HEIFER MATING

These days most people believe it is essential to breed from yearling heifers.  This way you optimise your herd’s profitability as well as maximising the genetic gain.
The chance of calving difficulties is minimised by the careful selection of sires to put over these heifers.
The following is part of an article by Russell Priest, Beef Genetics Coordinator, Meat and Wool, NZ. 
Ph: 063234484  Fax:  063233878  mobile: 0274369372
We feel it explains clearly how to go about selection.

“Place plenty of emphasis on the Calving Ease (Direct) EBV when buying your bulls.

Remember, the higher (more positive) the Calving Ease (Direct) EBV, the more easily the calves will be born.

Don’t neglect the Caving Ease (Maternal) EBV if you are going to use heifer progeny as herd replacement, because this will influence the ease with which a bull’s daughters will calve.
The breed average EBV or percentile band information will enable you to benchmark a bull within the breed.”
“Target bulls with Birth Weight EBVs which are at least below the breed average and remember the BW and Growth rates are quite strongly related. 
Low BWs generally result in low growth rates and vice versa, thought there are more bulls being bred nowadays which break this genetic relationship.”      Look for these.

At Kakahu we believe that the Calving Ease EBVs should always be available in sale catalogues. There will always be a variation in any herd, and it is essential for buyers to be able to select. These EBVs are not such a concern for cow mating in the same way as for heifer mating.  A catalogue that leaves them out often has something to hide.
 
There are methods of finding out all the information that is not in the catalogue. 

  1. Go to www.nzangus.co.nz 
  2. Click on EBV enquiries
  3. Put in the Kakahu Herd No. plus a % sign. (this says "Find All animals beginning with this Herd No".). The Kakahu Herd No. is 13300.
  4. Put in the calving year.
  5. Click Search

The Australasian average for the breed will be found at the bottom of the list.
It is a good idea to click on “Show Index Values”. Again the breed average is at the bottom of the list. 
As Russell Priest says
“ Selection of bulls to mate with yearling heifers has been made much easier with the introduction of the Ease of Calving Index by the Angus Breed Society and The Dairy Maternal Index by the Hereford Breed Society. 
These Indexes rank bulls on their ability to generate profit per cow mated in a production system, in which the main focus is to minimise calving problems, without neglecting subsequent growth.
Indexes gather traits, those affecting costs and returns, which are of economic importance in specific production systems and place an economic value on these.  In using the index system, it is still wise to view the component EBVs to ensure you are comfortable with these before making your final selection.”

Now, having selected all the bulls in the catalogue that suit your criteria, go and view the bulls in question. 
Avoid any with heavy shoulders, and very heavy bone structure. 
They should have a minimum scrotal circumference of 28cm.
And, as Russell Priest says, 
“ Remember, yearling bulls do not necessarily leave smaller calves than older bulls.  Birth Weight depends on the level of feeding of the cow/heifer and the BW genes carried by the parents of the calf, and it is completely independent of the age of the sire.”

Feed yearling bulls on generous rations of high-quality grass before, during and after mating because they are still growing rapidly at this age and their fertility is likely to suffer if fed inadequately.”