Five tips to help you achieve your desired mating length and empty rate
For block calving herds there are only 12 weeks between the planned start of calving and the next mating period.
Having all cows finished calving before mating commences becomes very important. Cows do have a natural calving spread of ± 10 days around their due date, so farmers may shorten their total mating period in an attempt to reduce the number of late calvers.
This comes at a price so requires careful thought. The shorter the mating period is the higher the 3 and 6 week in-calf rate need to be if you are to likely avoid an unexpectedly high empty rate!
Adapted from the ‘expected empty rate (%) given 6-week in- calf rate and length of mating’ table – DairyNZ's The InCalf Book (page 127)
1. Understand your past calving pattern, submission rate, non-return rate and empty rate
2. Be realistic
Don’t cut too short in a single year, or else budget for the higher empty rate
3. Be proactive
Make sure you hit first round submission and conception rate targets
4. Monitor progress and be flexible
As you near the end of mating date, reassess how many cows you are seeing bulling each week. Is it still the right decision? What will you do with the late calves? Are they still valuable? Are there a group of cows you’ll continue to mate to AI and disregard the rest (e.g. good young cows)? Are there Short Gestation Length (SGL™) options that could help?
5. Spilt calving herds may consider shortening one mating period and rolling cows over into the other
Some successful farms manage with 2x 6 week mating periods = 12 weeks per annum total mating.
Be careful not to roll cows over a second time, as you’ll build up infertility in the herd. Consider your feed supply and demand curves - it may suit to calve different sized groups in spring and autumn in which case you’ll need to have a longer mating period f or the larger group or the numbers could get out of balance.
For more information, see your farm consultant or vet.