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INFLUENCE OF SYNCHRONIZED OVULATION AND PRE- SYNCHRONIZATION ON PREGNANCY RATES USED TIMED AI IN LACTATING DAIRY COWS

INFLUENCE OF SYNCHRONIZED OVULATION AND PRE- SYNCHRONIZATION ON PREGNANCY RATES USED TIMED AI IN LACTATING DAIRY COWS . G. Gabor and F. Toth. Introduction.

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INFLUENCE OF SYNCHRONIZED OVULATION AND PRE- SYNCHRONIZATION ON PREGNANCY RATES USED TIMED AI IN LACTATING DAIRY COWS

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  1. INFLUENCE OF SYNCHRONIZED OVULATION AND PRE- SYNCHRONIZATIONON PREGNANCY RATES USED TIMEDAI IN LACTATING DAIRY COWS G. Gabor and F. Toth

  2. Introduction • Despite increases in milk production, on many farms in Hungary, management (including nutrition, collection and analysis of data, and estrus detection) has often not increased commensurate with increases in herd size. Consequently, there has been a general trend for decreased reproductive performance. Re-breeding of open cows is one of the most effective tools in decreasing of the parturition interval in dairy cows.

  3. Objectives • The primary objective of the present study was to determine pregnancy rate in lactating dairy cows in Hungary synchronized with the Ovsynch and Provsynch (pre-synchronization and ovulation synchronization) regimens.

  4. METHODSAnimals • A field trial was conducted on four Hungarian dairy farms. The cattle were crossbred Holstein-Friesian (R3-R4), with an average of 600 lactating cows. The mean milk productions of the farms were between 7500 and 8500 kg per year.

  5. All cows were diagnosed with cystic ovarian disease or metritis were excluded from the trial and treated (Figure 1). Furthermore, cows with small, inactive ovaries (ovarian diameter 1.0 to 1.5 cm), were also excluded. The remaining cows were used in the trial and were treated with an Ovsynch or Provsynch protocol. Pregnancy was checked by rectal ultrasonography – see Figure 2- (6 Mhz-linear transducer, Scanner 100 LC Vet, Pie Medical, Maastricht, Nederland)or PSPB test (Biopryn™, Biotracking LLC, Moscow, ID, US).

  6. Figure 1: Ultrasonic appearance of the cattle ovary Luteal cyst Normal ovary

  7. Figure 2: Ultrasonic appearance of the bovine fetus at different stages of the pregnancy

  8. PSPB is a novel protein and located in the giant binucleate cells of the trophoblastic ectoderm of the placenta and this indicated that it was either synthesized or sequestered by those cells.Migration of these cells result the appearance of PSPB in the maternal circulation. • PSPB is detectable in serum from 24 to 282 (parturition) days of gestation and can be applied reliably in dairy cow herds at 28 to 30 days after breading. Complete clearence of the protein from blood may not occur until 80 to 100 days after parturition. For this reason testing of blood for a new pregnancy following parturition may give false positive tests. • An ELISA test (BioPryn™ by BioTracking LLC) has been developed for the examination of the PSPB in cattle 30 days after AI (at least 90 days after the previous parturition) (Figure 3).

  9. Figure 3: Biopryn™ PSPB ELISA test (yellow wells represent pregnant samples)

  10. OVSYNCH • The Ovsynch protocol consisted of 150 mg GnRH (Fertagyl®; Intervet, The Netherlands) on Days 0 and 9 and 500 mg cloprostenol sodium (Estrumate®; Schering-Plough, Kenilworth, N.J., US.) on Day 7. Timed AI was carried out 16-24 hours after the 2nd GnRH injection. The Ovsynch was carried out 79  3.8 days (range, 75 to 83) postpartum.

  11. PROVSYNCH • Pre-synchronization was achieved with a standard estrous synchronization protocol (PGF2agiven twice at a 14-day interval) with the Ovsynch program, initiated 12 days after the second injection of PGF2a. All injections were given im. The mean ( SE) interval from calving to the start of the Provsynch protocol was 35  1.7 d (range, 33 to 37).

  12. RESULTS Table 1: Pregnancy rates followed the synchronization protocols

  13. Table 2: Differences of the reproductive efficiency of the different protocols at different farms

  14. DISCUSSION • Large differences of the reproductive efficiency occurred among the farms.Nutrition and season effects probably caused these differences on the four farms. It can be stated that the reproduction management also influenced the effectivity of the novel treatments as well.

  15. CONCLUSIONS • New technologies usually help precisely manipulate reproductive function in lactating dairy cows. On the basis of our findings, these regimens would help to reduce anestrus, parturition interval, synchronize return services and enhance embryo survival.

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