INFLUENCE OF SYNCHRONIZED OVULATION AND PRE- SYNCHRONIZATIONON PREGNANCY RATES USED TIMEDAI IN LACTATING DAIRY COWS

G. Gabor and F. Toth

IntroductionDespite 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.

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Change of parturition interval in controlled herds in Hungary between 1970 - 2002

Munka1

YearsParturition interval (days)

1970399

1971398

1972400

1973399

1974398

1975400

1976403

1977402

1978401

1979400

1980399

1981400

1982397

1983399

1984403

1985400

1986406

1987408

1988408

1989410

1990407

1991413

1992411

1993415

1994416

1995415

1996422

1997419

1998420

1999418

2000424

2001426

2002426

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ObjectivesThe 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.

METHODS

AnimalsA 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.

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).

Luteal cystNormal ovaryFigure 1: Ultrasonic appearance of the cattle ovary

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

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).

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

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.

PROVSYNCHPre-synchronization was achieved with a standard estrous synchronization protocol (PGF2a given 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).

RESULTSTable 1: Pregnancy rates followed the synchronization protocols

Sheet1

Number of AI1742

Correct positive diagnosis772

Correct negative diagnosis638

Fals positive diagnosis292

Fals negative diagnosis40

Sensitivity95.1

Specificity68.6

Positive predicted value72.6

Negative predicted value94.1

Number of AI336

Correct positive diagnosis214

Correct negative diagnosis109

Fals positive diagnosis13

Fals negative diagnosis0

Sensitivity100

Specificity89.1

Positive predicted value94

Negative predicted value100

ProvsynchOvsynch

Farm I43.40%29.40%

Farm II-47.10%

Farm III29.90%35.40%

Farm IV-25.70%

ProvsynchOvsynch

Number of AI332538

Number of pregnant cows127182

Number of open cows206317

Pregnancy rate38.30%33.80%

Sheet2

Sheet3

MBD00152438.xls

Sheet1

termkenyts szma1742

korrekt pozitv772

korrekt negatv638

fals pozitv292

fals negatv40

rzkenysg95.07

negatv elrejelzs94.1

Termkenyts336

Korrekt pozitv316

Korrekt negatv164

Fals pozitv20

Fals negatv0

rzkenysg100

Pozitv elrejelzs94

Negatv elrejelzs100

Sheet2

EmbryonicEmbryonicTotalTotalEmbryonic loss

Pregnantlosslossno. of losslossbetweenMilk kg /Correlation

FarmsNo. of cowsbetweenbetweenbetween%25-36 days36-60 dayscow/year

25-36 days36-60 days25-60 days%

I.1908212915.34.211.18000milk / total loss0.73

II.2515444919.5217.59500milk / loss (25-36 days)-0.36

III.175215179.71.18.67500milk/ implantation0.91

IV.1617172414.94.310.67000

Total777229711914.82.911.98000

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

Sheet1

Number of AI1742

Correct positive diagnosis772

Correct negative diagnosis638

Fals positive diagnosis292

Fals negative diagnosis40

Sensitivity95.1

Specificity68.6

Positive predicted value72.6

Negative predicted value94.1

Number of AI336

Correct positive diagnosis214

Correct negative diagnosis109

Fals positive diagnosis13

Fals negative diagnosis0

Sensitivity100

Specificity89.1

Positive predicted value94

Negative predicted value100

ProvsynchOvsynch

Farm I43.40%29.40%

Farm II-47.10%

Farm III29.90%35.40%

Farm IV-25.70%

Sheet2

Sheet3

MBD00152438.xls

Sheet1

termkenyts szma1742

korrekt pozitv772

korrekt negatv638

fals pozitv292

fals negatv40

rzkenysg95.07

negatv elrejelzs94.1

Termkenyts336

Korrekt pozitv316

Korrekt negatv164

Fals pozitv20

Fals negatv0

rzkenysg100

Pozitv elrejelzs94

Negatv elrejelzs100

Sheet2

EmbryonicEmbryonicTotalTotalEmbryonic loss

Pregnantlosslossno. of losslossbetweenMilk kg /Correlation

FarmsNo. of cowsbetweenbetweenbetween%25-36 days36-60 dayscow/year

25-36 days36-60 days25-60 days%

I.1908212915.34.211.18000milk / total loss0.73

II.2515444919.5217.59500milk / loss (25-36 days)-0.36

III.175215179.71.18.67500milk/ implantation0.91

IV.1617172414.94.310.67000

Total777229711914.82.911.98000

DISCUSSIONLarge 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.

CONCLUSIONSNew 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.