Yearling Heifer Mating
Stephen
T. Morris
Nutritional
Management of Pastoral Animal Production and Health
Institute of Veterinary, Animal
& Biomedical Sciences, Massey
University
(Background Notes for Monitor Farm Open day at The Thomsen Family
farm, Patoka, Hawkes Bay 20 March 2002)
Successful yearling heifer mating is the major opportunity to increase
profitability in most beef breeding herds. Practiced in only 30%
of heifers on beef cattle farms
Need to be aware of the management requirements for practice to
be successful
Reasons farmers do not mate heifers
- calving problems
- low in-calf rates
- re-breeding problems at 27 months
- stunting of heifers growth and mature size
- an extra mob to look after
- more small calves
- extra feed over winter required to grow heifers
- more management skills required
Benefits of calving heifers as 2 year olds
- Lower ratio of non productive animals in herd
- The unproductive life of each female in herd is reduced
- Lifetime output is increased
- Provides a good basis for selecting replacements
There are some limitations to successful adoption
- Stage of farm development
- Heifers not reached puberty
- Not reached a critical minimum liveweight
- Loss of a dry mob of stock a “buffer” mob
- Inappropriate use of sires on heifers – resulting in
calving problems
- Calves are sometimes lighter
- Lower % get back in calf as three year old
Need a management package to be successful
- Set a growth path from weaning to minimum joining weight (specific
for farm and breed or cross
- Use a small breed type and bulls with low or negative EBV for
birthweight
- mate for 42 days only at the same time as cows (this is important)
- Overmate (mate more heifers than needed as replacements) then
cull
- Feed as a growing animal until last 2months of pregnancy (450
kg) then M
- ensure heifers calve in ‘fit’ condition
Aim For
- 85 % pregnant after 42 day mating
- 60-70% calving in first 21 days
- 90 % calf survival
- 90% pregnant as rising 3 year olds
but note there are additional feed costs and if yearling heifer
in-calf rates are less than 70 % then there may be no benefits
Use restricted heifer mating periods as method of tightening the
calving duration in main herd Calving pattern (number in first
21 days is crucial to this).
Date added: 16 September 2002
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