By Kelley Neuhold, Ph.D.
Heifer synchronization is one of the best technologies to help add to the bottom line of a ranch. Synchronizing heifers can increase the profit of a ranch by producing heavier calves, increasing the longevity of females, reduce labor cost associated with AI and genetic improvement through the use of superior sires. We know that older calves weigh more and if we get more heifers to calve in the first 21 days of the calving period the weaning weight of calves will increase. This will also increase the possibility of heifers rebreeding earlier and staying in the herd longer. Advantages of Synchronizing heifers over cows are a higher conception rate at timed AI then cows and no calves to sort off and care for.
To successfully synchronize heifers, they must be sexually mature. To reach sexual maturity research would suggest that heifers must be 55 to 65% of mature body weight with adequate body condition (5 on a BCS scale of 1-9) and of an appropriate age. Historical research would say a minimum of 12 to 13 months old, however, as genetics change, the age to puberty seems to be decreasing. Having heifers on an increasing plane of nutrition prior to breeding will increase conception rates of heifers especially those heifers marginal on body weight or body condition. There is evidence that some synchronization protocols will bring heifers that have not cycled in to estrous, however, if the heifer is physically incapable of cycling, she will not cycle.
Heifer synchronization protocol has been well researched and ranges from the very simple to the very complex. When picking a protocol it is important to think about the goals for synchronization and how that protocol will work on your operation. The use of AI with synchronization can be a powerful tool, but heifer can be synchronized prior to natural service if the goal is shorter calving season or older calves at weaning. Feeding melengestrol acetate (MGA) for 14 days prior to turning bulls out maybe the simplest and effective way to synchronize heifers. MGA can be fed through a total mixed ration or hand fed in a cake or other pellet daily.
If fixed-timed AI is the preferred breeding method then a more complex protocol will be needed. A protocol referred to as “7 day CO Sync + CIDR” would be a great option. It requires the heifers to be in a chute 3 times including AI which is minimal for fixed timed AI protocols. With fixed-timed AI you can expect a 65 to 75% conception rate with proper protocol, good AI technicians and quality semen.
If you haven’t considered synchronizing heifers on your operation it would be time well spent and could help increase profit for your cattle operation. For more information contact QLF technical support or your local semen provider.