Administration of prostaglandin F-2 alpha 14 d before initiating a G6G or a G7G timed artificial insemination protocol increased circulating progesterone prior to artificial insemination and reduced pregnancy loss in multiparous Holstein cows

作者：Dirandeh E^*; Roodbari A Rezaei; Gholizadeh M; Deldar H; Masoumi R; Kazemifard M; Colazo M G

来源：Journal of Dairy Science, 2015, 98(8): 5414-5421.

DOI：10.3168/jds.2015-9417

• multiparous Holstein cow
• G6G
• progesterone
• ultrasonography

The objectives of this study were to determine the effect of PGF(2 alpha), treatment 14 d before the initiation of a G6G or G7G (PGF(2 alpha), 2 d, GnRH, 6 or 7 d, Ovsynch) protocol on ovarian response, synchronization protocol on ovarian response, progesterone (P-4) concentration, pregnancy per AT (P/AI), and pregnancy loss in multiparous Holstein cows. Cows (3.6 +/- 1.1 lactations and yielding >30 kg/d of milk) were randomly assigned to 1 of 4 timed artificial insemination (TAI) protocols: 1) G6G (n = 240), one injection of PGF(2 alpha), GnRH 2 d later and a 7-d Ovsynch protocol (GnRH, 7 d, PGF(2 alpha), 56 h, GnRH 16 h TAI) was initiated 6 d later; 2) PG6G (n = 250), PGF(2 alpha), 14 d before the initiation of the G6G protocol; 3) G7G (n = 200), one injection of PGF(2 alpha), GnRH 2 d later, and a 7-d Ovsynch protocol initiated 7 d later; and (4) PG7G (n = 200), a PGF(2 alpha), injection 14 d before the initiation of the G7G protocol. Blood samples from a subset of 269 cows were collected at the times of first and second GnRH, and PGF(2 alpha), of the Ovsynch protocol to measure P-4. Ultrasound examinations were performed to evaluate ovarian response to GnRH and PGF(2 alpha) of Ovsynch, and to determine pregnancy status at 32 and 60 d after TAI. The proportion of cows with high (>= 1 ng/mL) P-4 at first GnRH of Ovsynch was greater for PG6G and PG7G compared with G6G and G7G groups (combined 79.7 vs. 59.3%). In addition, mean (+/- SEM) plasma P-4 concentration (ng/mL) at PGF(2 alpha) of Ovsynch was also greater in PG6G (6.5 0.2) and PG7G (6.7 0.3) compared with G6G (5.1 0.2) and G7G (5.0 0.2). Cows given PGF(2 alpha), 14 d before initiating a G6G or a G7G TAI (PG6G and PG7G) tended to have a greater P/AI at 32 d compared with those cows not receiving PGF(2 alpha) (G6G and G7G). However, P/AI at 60 d was greater in cows subjected to PG6G and PG7G protocols (31.1 vs. 39.2%), with a lower pregnancy loss between 32 and 60 d (11.65 vs. 19.7%). In summary, administration of PGF(2 alpha) 14 d before initiating a G60 or a G7G TAI protocol increased P-4 concentrations before artificial insemination and late embryonic/early fetal survival in multiparous Holstein cows.

• 出版日期2015-8