Show Me Synch study improves heifer breeding
By Scott Poock, University of Missouri Dairy Veterinarian
There has been a great deal of interest in synchronizing dairy heifers for breeding. The University of Missouri's Foremost Dairy was looking for a way to group breed their heifers when breeding season began in December, 2008. Daniel Mallory, a graduate student of Dr. Dave Patterson, has been working with a protocol named "Show Me Synch" in beef heifers.
The protocol involves the use of a CIDR and prostaglandin. The CIDR is inserted for two weeks (14 days). Sixteen (16) days after removing the CIDR, the heifers receive an injection of prostaglandin (lutalyse, estrumate, estroplan, etc.) and are then bred on signs of estrus for the next six days. Dr. Patterson, Daniel Mallory, and the Genex group are researching timed breeding in beef heifers and cows.
In December of 2008, Foremost Dairy used the Show Me Synch program on 49 Holstein and Guernsey heifers. Estrotect patches were placed on the heifers to aid in heat detection. Due to the fact that they were using Gender Selected semen, the heifers were bred by the AM/PM rule after detection of standing estrus. In five days they bred 47 out of the 49 heifers.
The largest percentage of heifers were bred at 60 and 72 hours after the receiving prostaglandin. Subsequently, 27 of the 47 bred heifers conceived (55%). This was an improvement for conception rate using the Gender Selected semen.
Given the success accomplished with beef cattle and Foremost's dairy heifers, Drs. Matt Lucy, MU reproductive physiology, Dave Patterson, MU Extension beef reproduction, and Scott Poock, MU Commercial Agriculture dairy veterinarian, developed additional field trials with dairy heifers.
Seasonal grazing herds have a tight calving window like beef herds. Therefore, the Show Me Synch program was instituted on several grazing dairies, as well as a large traditional dairy. At the traditional dairy the 209 heifers were split between the Show Me Synch program (105) and a more common way of synchronizing by injecting a group of heifers (104) with prostaglandin only.
All the heifers at the traditional dairy were weighed and palpated for reproductive tract scores (RTS) prior at the start of the trial. The heifers were sorted by weight and RTS. Once again, due to the fact that heifers were bred to Gender Selected semen, estrotect patches and heat detection were used.
The heifers were bred using the AM/PM rule. At this point, only breeding data is complete, but the results are encouraging. Of the 105 heifers on the Show Me Synch program, 96 were bred primarily over two days. In contrast, the prostaglandin-only heifers had 69 of the 104 bred, spread over a six day period.
Likewise, on the two grazing dairies, a large percentage of heifers showing signs of estrus in a tight window were observed. Of the 120 heifers that were synchronized, 107 showed heat and were bred. One farm bred on the AM/PM rule because of the use of Gender Selected semen. The second farm bred once a day based on estrus signs using estrotect patches.
What does this all mean? Pregnancy check data is still needed, but the estrus response has been favorable. The synchronization has been tight with heifers expressing heat within 48 to 66 hours after the prostaglandin. Dr. Patterson, Daniel Mallory, and Genex's latest data on timed-breeding will be added to the present data.
The trials will be repeated with dairy heifers. Kurt Watson of Genex suggests looking at the economics of synchronizing and the use of Gender Selected semen. Joe Horner of the MU Commercial Agriculture Dairy team will analyze the economics of the study once pregnancy results are computed in July and August, and all data has been submitted.
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