Many dairy farmers are asking questions about fertility and herd reproductive performance, particularly when the time for joining approaches. If we get the basics right, significant improvements can be made. Let’s list a few key targets:
Aim for a 21 day Submission Rate of 80% or greater.
Submission Rate (SR)
SR’s are hugely influenced by accurate heat detection and by identifying non-cycling cows BEFORE joining. Remember that heat detection aids are merely AIDS, there is no substitute for physically watching your cows.
Traditionally, heats are detected for 21-25 days prior to joining; cows not observed to be on heat during this time are classified as non-cyclers, and can be treated at the START of joining. There are multiple methods available to reduce the duration of premating heat detection. (Single PG, double PG, OvSynch, PreSynch etc etc) Each method has its advantages and disadvantages. For more specific information about your herd, please ask to speak to one of our vets.
Aim for a 6 week in-calf rate of 65% or greater.
The key drivers of the 6 week in-calf rate are SR, (if they aren’t joined, they can’t be in calf!!) and Conception Rates (CR).
Conception requires the delivery of fertile semen into a clean uterus at the time of ovulation. Fertile semen should be provided for you by the bull himself or via the A.I. Tech. Infertile semen is a rare problem which, when encountered, can have quite devastating effects.
A cow’s uterus should be ready to conceive 30 days after calving; however this is not always the case. In the past, we have recommended checking the high risk cows and “washing out” the dirty ones. A recent study carried out in Gippsland, shows there is significant benefit in “metri-checking” the entire herd prior to joining. Some of our clients have seen a 10% increase in their CR following whole herd checks. The best timing for this is still unclear, but facilities usually dictate either whole herd checks, or group checks. For advice about your individual setup, please call us at the clinic.
The timing of delivery relies on accurate heat detection.
Cows should calve with a body condition score between 4.5 and 5.5.
At the start of joining they should be 4 to 5. If 15% of your herd is below a body condition of 4, you can expect at least a 10% reduction in 6 week in-calf rates! Body Condition should be monitored throughout lactation, with cows putting on condition (if required) in late lactation. Weight loss should be kept to a minimum during the dry period, early lactation and prior to joining. Light cows AND excessively fat cows that have lost condition prior to joining have the lowest fertility scores.
How to body condition score a cow
As always, remember to Vibrio your bulls, and give them plenty of rest between “shifts”.