TY  - JOUR
T1  - Effects of Early Postpartum GnRH and Prostaglandin F<SUB>2&#945;</SUB> Administration on Reproductive Activity and Ovulation Synchronization in Lactating Dairy Cows
AU - Ryan, P.L. AU - Willard, S.T. AU - Fuquay, J.W. AU - Williams, A. AU - Tucker, W.B. AU - Sanchez, H.L. AU - Tucker, A.L. 
JO  - Journal of Animal and Veterinary Advances
VL  - 10
IS  - 7
SP  - 900
EP  - 908
PY  - 2011
DA  - 2001/08/19
SN  - 1680-5593
DO  - javaa.2011.900.908
UR  - https://makhillpublications.co/view-article.php?doi=javaa.2011.900.908
KW  - concentration
KW  -treatment
KW  -Postpartum estrual activity
KW  -ovulation synchronization
KW  -ovulation synchronization
KW  -uterine involution
AB  - The objectives of this study were to determine the efficacy of GnRH and PGF<SUB>2&#945;</SUB> for inducing early Postpartum (PP) estrual activity, hastening uterine involution and enhancing ovulation synchronization in lactating dairy cows. About 40 Holstein and Jersey cows were assigned at calving to 1 of 3 Treatments (Trt) and balanced by breed: Trt 1 (Control; n = 13) received an injection of saline on days 15 and 25 PP; Trt 2 (n = 14) received saline and PGF<SUB>2&#945; </SUB>injections on days 15 and 25 PP, respectively; Trt 3 (n = 13) received GnRH and PGF<SUB>2&#945; </SUB>injections on days 15 and 25 PP, respectively. Reproductive function was monitored through day 58 PP via electronic heat detection, rectal palpation for uterine tone, ultrasonography of ovarian structures and blood samples obtained 3 times week<SUP>-1</SUP> for serum Progesterone (P<SUB>4</SUB>) analysis. On day 58 PP, an ovulation synchronization protocol was initiated as follows: GnRH given on day 0, PGF<SUB>2&#945;</SUB> administered on day 7, GnRH given again on day 9 and artificial insemination conducted 16 h after the 2nd GnRH injection. In both Trt 2 and Trt 3, serum P<SUB>4</SUB> fell sharply after the PGF<SUB>2&#945;</SUB> injection at 25 days PP. An interaction of treatment by sample time (p&lt;0.05) associated with treatment effects (PGF<SUB>2&#945; </SUB>vs. saline) on P<SUB>4</SUB> concentrations was observed. Postpartum estrual activity (p&gt;0.10), rate of uterine involution (p&gt;0.05), follicular dynamics (p&gt;0.10) and P<SUB>4</SUB> concentrations (p&lt;0.10) did not differ between treatment groups prior to ovulation synchronization. Pregnancy rate following artificial insemination also did not differ between breeds (p&gt;0.05) or among treatment groups (p&gt;0.05) and for all cows was 50% (20/40). In summary, early postpartum hormonal treatments did not influence uterine involution, follicular development or estrus activity compared to non-Treated controls (Trt 1). Moreover, early postpartum (days 15-25 PP) treatment with GnRH and/or PGF<SUB>2&#945;</SUB> did not enhance subsequent ovulation synchronization nor conception rates for lactating dairy cows in this study.
ER  -