Hickson Heifer Mating

Report
Yearling heifer mating
Rebecca Hickson
Outline
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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
Reason
Important or very important
Increased profit
80%
Shorter unproductive period of heifers
78%
More calves per cow over her lifetime
66%
Increased rate of genetic gain
50%
Earlier selection of replacements
40%
Reduces mature size (maintenance) of heifers
28%
Why NOT calve heifers?
Reason
Important or very important
Concerned about rebreeding of 2yo heifers
60%
Need mob (empty R2 heifers) that can be fed less
when required
51%
Stunting of heifers mature size
49%
High dystocia in 2yo heifers
37%
Requires different management skills
37%
Want a higher pregnancy rate than could be
achieved at 15 months
37%
Returns do not justify the extra costs
23%
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
dystocia
• Rebreeding at 2 not a big problem (?)
Line
Angus
Angus x Friesian
Angus x Jersey
Post-partum anoestrus
interval (days)
101
Pregnancy rate to
second joining
91%
97
90
96%
100%
Try it!
But choose your bull wisely
Thanks to Beef + Lamb NZ for funding
the research underpinning this talk

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