عنوان انگلیسی مقاله:
Prostaglandin F2a influences pre-ovulatory follicle characteristics and pregnancy per AI in anovular dairy cows
ترجمه فارسی عنوان مقاله:
پروستاگلاندین F2a بر خصوصیات فولیکول قبل از تخمک گذاری و بارداری در هوش مصنوعی در گاوهای شیری بی قاعده تأثیر می گذارد
Sciencedirect - Elsevier - Theriogenology, 153 (2020) 122-132. doi:10.1016/j.theriogenology.2020.04.038
F.R. Lopes Jr. a, b, L.M. Silva b, R. Zimpel b, A.K. Munhoz a, A. Vieira-Neto b, M.H.C. Pereira a, M. Poindexter b, M.L. Gambarini b, W.W. Thatcher b, c, J.L.M. Vasconcelos a, J.E.P. Santos b, c,
Objectives were to determine the effects of a dose of PGF2a administered 2 days before timed artificial
insemination (AI) on LH pulsatility, characteristics of the pre-ovulatory follicle, and pregnancy per
artificial insemination (P/AI) in anovular dairy cows, particularly in cows not subjected to hyperthermia.
In experiment 1, 2,011 lactating Holstein cows had ovaries scanned by ultrasound to determine corpus
luteum (CL) presence and only those without a CL in two consecutive exams were enrolled (n ¼ 437).
Cows had the estrous cycle synchronized with an estradiol-progesterone based protocol starting on
experiment Day 11 and timed AI on Day 0. Cows were assigned randomly to receive a single dose of
25 mg of PGF2a as dinoprost on Day 4 (1PGF, n ¼ 222) or two doses of 25 mg each of PGF2a, one on
Day 4 and one on Day 2 (2PGF, n ¼ 215). Rectal temperatures were evaluated on the day of AI and 7
days later and cows were classified as being normothermic (<39.1 C) or hyperthermic (39.1 C).
Ovulatory responses and P/AI were determined. In experiment 2, cows with regressed CL were exposed
to low concentrations of progesterone and then randomly assigned to the same estrous synchronization
protocol and treatments, 1PGF (n ¼ 28) and 2PGF (n ¼ 28). Blood was sampled and analyzed for concentrations
of progesterone, and for concentrations of LH and 13,14-dihydro-15-keto-PGF2a metabolite
(PGFM) every 15 min starting 1 h before to 6 h after treatments and then every 2 h from 12 to 59 h after
treatments. The pre-ovulatory follicle was aspirated 44 h after treatments and concentrations of estradiol
quantified. In experiment 1, treatment of anovular cows with a second dose of PGF2a increased P/AI in
normothermic cows (19.8 [18/91] vs. 38.8% [31/80]), but not in hyperthermic cows. Synchronization was
not affected by treatment, but it was greater for normothermic than hyperthermic cows (87.1 [149/171]
vs. 77.8% [207/266]). When only synchronized cows were evaluated, the same responses were observed;
treatment with 2PGF increased P/AI compared with 1PGF in normothermic cows (23.1 [18/78] vs. 43.7%
[31/71]), but not in hyperthermic cows. In experiment 2, administration of 25 mg of dinoprost in 2PGF
resulted in concentrations of PGFM 26-fold greater than 1PGF in the first 6 h after treatment (48 vs.
1,242 pg/mL). Cows receiving 2PGF had smaller basal LH concentration (0.57 vs. 0.46 ng/mL) and less
frequent LH pulses (4.5 vs. 3.9 pulses/6 h), but duration of the LH surge was longer for 2PGF than 1PGF
(13.1 vs. 15.5 h). Treatment with 2PGF increased the diameter and volume of the pre-ovulatory follicle,
and concentration of estradiol (115 vs. 262 ng/mL) and total follicular estradiol content (124 vs. 505 ng)
compared with 1PGF. Collectively, these results suggest that PGF2a has a role in fertility of anovular cows
that is unrelated to its luteolytic effect.
Keywords: Anovular | Follicle | Dairy cow | Prostaglandin