Hickson Heifer Mating

Yearling heifer mating
Rebecca Hickson
Profitability of calving heifers
Beef cow efficiency
Why calve heifers
Why not calve heifers
Performance of heifers in industry
How to calve heifers
The costs and the income
• The 2-year-olds will be there anyway
– How much extra has it cost you to feed them to support
pregnancy and lactation?
• More calves = more income from the beef herd
– What is an extra calf worth?
Example of extra costs
– Assume heifers are 346 kg at 15 months (joining), 484 kg at 31
months (weaning)
– Calves are 34 kg at birth, 232 kg at weaning at 208 days of age;
6 kg milk/day
– Pasture is 11 MJ ME per kg DM
• Non pregnant heifer eats 2565 kg DM
• Heifer and calf eat 3713 kg DM
• An extra 1149 kg DM (45%) over empty heifer
• At 12c/kg DM this is an extra $138 in feed eaten
Example of extra income
232 kg weaner at $2.20/kg = $510??
Efficiency (or lack of it)
• Beef cows are exceptionally inefficient
– 70% of feed requirements are for maintenance
• Efficiency depends on
– Number of calves weaned
– Weight of calves weaned
– Feed requirements (live weight) of cows
Increasing efficiency
• Smaller cows – breed and EBVs
• Bigger calves – breed and EBVs, ‘milky’ cows
• More calves
– National calving percentage hardly changed in 20 years
– Getting calves from the 2-year-old heifers increases number of
calves far more than any tweaking of calving percentage of
mature cows
Why calve 2-year-olds?
Survey of 331 farmers in charge of 16,000 heifers
Important or very important
Increased profit
Shorter unproductive period of heifers
More calves per cow over her lifetime
Increased rate of genetic gain
Earlier selection of replacements
Reduces mature size (maintenance) of heifers
Why NOT calve heifers?
Important or very important
Concerned about rebreeding of 2yo heifers
Need mob (empty R2 heifers) that can be fed less
when required
Stunting of heifers mature size
High dystocia in 2yo heifers
Requires different management skills
Want a higher pregnancy rate than could be
achieved at 15 months
Returns do not justify the extra costs
Simulated profitability and dystocia
• Based on a simulated farm with a fixed feed
supply, and assuming an assisted birth killed
36% of calves and 11% of heifers…
• More profitable to calve 2yo heifers than 3yo
heifers as long as incidence of assistance
remained below 89%
Industry performance of 2yo heifers
• 86% pregnant per heifer joined
• 78% calves marked per heifer joined
• 9.6% heifers assisted at calving
– Of 386 assisted births:
• 36% of calves died
• 11% of heifers died
• 84% of heifers that calved at 2 calved again at 3
– 7% were empty, 9% culled for other reasons or died
Get heifers ready for joining
• Well grown
– Reach puberty (mean live weight 297 kg for Angus heifers)
– Get a ‘head start’ on the calf – reduce dystocia
Choosing the right bulls
• All about the EBVs!
– Direct calving ease (higher is better)
– Birth weight
– Accuracy: is birth weight measured in the herd you are buying
from? Do they calve their 2 year olds?
• Shape is of little (no?) importance, just birth weight
• Daughters’ calving ease EBV useful if choosing a bull to
father your replacements
Feeding during pregnancy
• Feeding in early pregnancy does not affect dystocia
– Losing 560 g/d from 6-12w of gestation reduced milk production
• Feeding in late pregnancy does not affect dystocia reliably
– Underfeeding can reduce milk yield, calf weight and pregnancy
rate to rebreeding
• Keep them within the range of ‘normal’, neither very thin
or very fat
Management at calving
• Where do you calve them?
• How often do you observe them?
• At what point do you assist?
Rebreeding & culling
• Cull heifers that don’t get pregnant at 15 months
• Dystocia at first calving does not imply future
• Rebreeding at 2 not a big problem (?)
Angus x Friesian
Angus x Jersey
Post-partum anoestrus
interval (days)
Pregnancy rate to
second joining
Try it!
But choose your bull wisely
Thanks to Beef + Lamb NZ for funding
the research underpinning this talk

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