Yearling heifer matingRebecca Hickson
• Profitability of calving heifers• Beef cow efficiency• Why calve heifers• Why not calve heifers• Performance of heifers in industry• How to calve heifers
Outline
• 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?
The costs and the income
– 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 costs
Example of extra income
232 kg weaner at $2.20/kg = $510??
• 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
Efficiency (or lack of it)
• 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
Increasing efficiency
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%
• 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%
Simulated profitability and dystocia
• 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
Industry performance of 2yo heifers
• Well grown– Reach puberty (mean live weight 297 kg for Angus heifers)– Get a ‘head start’ on the calf – reduce dystocia
Get heifers ready for joining
• 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
Choosing the right bulls
• 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
Feeding during pregnancy
• Where do you calve them? • How often do you observe them?• At what point do you assist?
Management at calving
• 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 (?)
Rebreeding & culling
Line Post-partum anoestrus interval (days)
Pregnancy rate to second joining
Angus 101 91%Angus x Friesian 97 96%Angus x Jersey 90 100%
Try it!But choose your bull wisely
Thanks to Beef + Lamb NZ for funding the research underpinning this talk