The Effectiveness of Cosynch Protocol in Dairy Heifers and Multiparous Cows
The aim of the present study was to evaluate the effects of Cosynch protocol on some reproductive parameters in Holstein multiparous cows (MC) (n = 54) and heifers (n = 53). Follicular development, presence of corpus luteum (CL) at different stages of Cosynch protocol, ovulation time and pregnancy rates were evaluated by ultrasonography in MCs and heifers. Pregnancy rates (PR) in MCs and heifers were found as 41% and 51% (P: 0.29, Z: -1.06). At the time of first Gonadotropinreleasing hormone (GnRH) (GnRH1), Prostaglandin F2a (PGF2a) and final GnRH (GnRH2) injections, PRs in heifers and MCs which had CL on their ovaries were detected as 47.4%-48.7% (P: 0.91, Z: 0.12), 60.5%-48.7% (P: 0. 30, Z: -1.4) and 62.1%-36.4% (P: 0.031, Z: -2.15) respectively. Ovulations occurred in 24-30 h interval after artificial insemination (AI) in MCs (50%) and heifers (35%) (P: 0.13, Z: 1.51). In conclusion, Cosynch protocol was found more effective and practical in heifers than MCs. In addition, ovulations that occurred before AI could be the reason of low conception rate for Ovsynch procedure in heifers.
The Effectiveness of Cosynch Protocol in Dairy Heifers and Multiparous Cows
The aim of the present study was to evaluate the effects of Cosynch protocol on some reproductive parameters in Holstein multiparous cows (MC) (n = 54) and heifers (n = 53). Follicular development, presence of corpus luteum (CL) at different stages of Cosynch protocol, ovulation time and pregnancy rates were evaluated by ultrasonography in MCs and heifers. Pregnancy rates (PR) in MCs and heifers were found as 41% and 51% (P: 0.29, Z: -1.06). At the time of first Gonadotropinreleasing hormone (GnRH) (GnRH1), Prostaglandin F2a (PGF2a) and final GnRH (GnRH2) injections, PRs in heifers and MCs which had CL on their ovaries were detected as 47.4%-48.7% (P: 0.91, Z: 0.12), 60.5%-48.7% (P: 0. 30, Z: -1.4) and 62.1%-36.4% (P: 0.031, Z: -2.15) respectively. Ovulations occurred in 24-30 h interval after artificial insemination (AI) in MCs (50%) and heifers (35%) (P: 0.13, Z: 1.51). In conclusion, Cosynch protocol was found more effective and practical in heifers than MCs. In addition, ovulations that occurred before AI could be the reason of low conception rate for Ovsynch procedure in heifers.
___
- Lucy, M.C., McDougall, S., Nation, D.P.: The use of hormonal treatments to improve the reproductive performance of lactating dairy cows in feedlot or pasteur-based management systems. Anim. Reprod. Sci., 2004; 82-83: 495-512.
- Thatcher, W.W., Moreira, F., Pancarci, S.M., Bartolome, J.A., Santos, J.E.P.: Strategies to optimize reproductive efficiency by regulation of ovarian function. Domest. Anim. Endocrinol., 2002; 23: 243-254.
- DeJarnette, J.M., Marshall, C.E.: Effects of pre-synchronization using combinations PGF2αand (or) GnRH on pregnancy rates of ovsynch-and cosynch-treated lactating Holstein cows. Anim. Reprod. Sci., 2003; 77: 51-60.
- Pursley, J.R., Silcox, R.W., Wiltbank, M.C.: Effect of time of artificial insemination on pregnancy rates, calving rates, pregnancy loss, and gender ratio after synchronization of ovulation in lactating dairy cows. J. Dairy Sci., 1998; 81: 2139- 2144.
- Dahlen, C.R., Lamb, G.C., Zehnder, C.M., Miller, L.R., DiCostanzo, A.: Fixed-time insemination in peripuberal, lightweight replacement beef heifers after estrus synchronization with PGF2alpha and GnRH. Theriogenology, 2003; 59: 1827- 1837.
- DeJarnette, J.M., Salverson, R.R., Marshall, C.E.: Incidence of premature estrus in lactating dairy cows and conception rates to standing estrus or fixed-time inseminations after synchronization using GnRH and PGF2α. Anim. Reprod. Sci., 2001; 67: 27-35.
- Colazo, M.G., Kastelic, J.P., Martinez, M.F., Whittaker, P.R., Wilde, R., Ambrose, J.D., Corbett, R., Mapletoft, R.J.: Fertility following fixed-time AI in CIDR-treated beef heifers given GnRH or estradiol cypionate and fed diets supplemented with flax seed or sun flower seed. Theriogenology, 2004; 61: 1115-1124.
- Pursley, J.R., Wiltbank, M.C., Stevenson, J.S., Ottobre, J.S., Garverick, H.A., Anderson, L.L.: Pregnancy rates per artificial insemination for cows and heifers inseminated at synchronized ovulation or synchronized estrus. J. Dairy Sci., 1997; 80: 295- 300.
- Taponen, J., Katila, T., Rodriguez-Martinez, H.: Induction of ovulation with gonadotropin-releasing hormone during proestrus in cattle: influence on subsequent follicular growth and luteal function. Anim. Reprod. Sci., 1999; 55: 91-105.
- Vasconcelos, J.L.M., Sartori, R., Oliveira, H.N., Guenther, J.G., Wiltbank, M.C.: Reduction in size of the ovulatory follicle reduces subsequent luteal size and pregnancy rate. Theriogenology, 2001; 56: 307-314.
- de Araujo Berber, R.C., Madureira, E.H., Baruselli, P.S.: Comparison of two ovsynch protocols (GnRH versus LH) for fixed timed insemination in buffalo (Bubalus bubalis). Theriogenology, 2002; 57: 1421-1430.
- Tenhagen, B.A., Surhold, R., Wittke, M., Vogel, C., Drillich, M., Heuwieser, W.: Use of ovsynch in dairy herds-differences between primiparous and multiparous cows. Anim. Reprod. Sci., 2004; 82: 1-11.
- Wolfenson, D., Inbar, G., Roth, Z., Kaim, M., Bloch, A., Braw-Tal, R.: Follicular dynamics and concentrations of steroids and gonadotropins in lactating cows and nulliparous heifers. Theriogenology, 2004; 62: 1042-1055.
- Tenhagen, B.A., Kuchenbuch, S., Heuwieser, W.: Timing of ovulation and fertility of heifers after synchronization of oestrus with GnRH and Prostaglandin F2α. Reprod. Domest. Anim., 2005; 40: 62-67.
- Martinez, M.F., Kastelic, J.P., Adams, G.P., Cook, B., Olson, W.O., Mapletoft, R.J.: The use of progestins in regimens for fixed-time artificial insemination in beef cattle. Theriogenology, 2002; 57: 1049-1059.
- Saumande, J., Humblot, P.: The variability in the interval between estrus and ovulation in cattle and its determinants. Anim. Reprod. Sci., 2005; 85: 171-182.
- Vasconcelos, J.L.M., Silcox, R.W., Rosa, G.J.M., Pursley, J.R., Wiltbank, M.C.: Synchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrus cycle in lactating dairy cows. Theriogenology, 1999; 52: 1067-1078.
- Tenhagen, B.A., Wittke, M., Vogel, C., Drillich, M., Heuwieser, W.: Timing of ovulation and conception rate in primiparous and multiparous cows after synchronization of ovulation with GnRH and PGF2α. Reprod. Domest. Anim., 2003; 38: 451-454.
- Pursley, J.R., Mee, M.O., Wiltbank, M.C.: Synchronization of ovulation in dairy cows using PGF2αand GnRH. Theriogenology, 1995; 44: 915-923.