Low progesterone concentration during the development of the first follicular wave reduces pregnancy per insemination of lactating dairy cows

Abstract

Objectives were to determine the effect of progesterone (P4) concentration on fertility of lactating dairy cows induced to ovulate follicles of the first follicular wave. Lactating dairy cows (n=989) at 38±3d postpartum were balanced by parity and body condition score and randomly assigned to 3 treatments: first follicular wave (FFW), first follicular wave with exogenous P4 (FFWP), or second follicular wave (SFW). All cows had their estrous cycle presynchronized with 2 injections of prostaglandin (PG) F(2α) given 14 d apart. Cows in the FFW and FFWP treatments started the ovulation synchronization protocol 3 d after the last PGF(2α) of the presynchronization protocol, whereas SFW cows received a GnRH injection (100 μg of gonadorelin diacetate; Cystorelin, Merial Ltd., Duluth, GA) 3 d after the last PGF(2α) of the presynchronization protocol and started the synchronization protocol 7 d later. The synchronization protocol consisted of GnRH on d -10, PGF(2α) on d -3, and GnRH concurrent with timed artificial insemination (AI) on d 0. Cows in the FFWP treatment received 2 controlled internal drug release inserts containing 1.38 g of P4 from d -8 to -3. Progesterone concentration was determined on d -10, -8, -6, -3, and 0 from all cows and at 7, 14, and 21 d after AI from a subsample of cows (n=170). Cows (n=715) had their ovaries scanned by ultrasound on d -10, -3, and 7 d. Pregnancy was diagnosed at 38 and 66 d after AI. Concentration of P4 from study d -8 to -3 was lowest for FFW cows (1.4±0.1 ng/mL) and similar between SFW (3.7±0.2 ng/mL) and FFWP (3.7±0.1 ng/mL) cows. Diameter of the dominant follicle on study d -3 was greater for FFW cows (16.5±0.3 mm) than for SFW cows (15.4±0.3 mm), but diameter of the dominant follicle of FFWP cows was not different (15.9±0.3 mm) compared with that of SFW and FFW cows. The incidence of multiple ovulation was largest for FFW cows (SFW=19.5, FFW=33.6, FFWP=19.0%), but pregnancy per AI (P/AI) at 66 d was smallest for FFW cows (SFW=38.9, FFW=22.3, FFWP=32.0%). Anovular cows in the SFW (19.4 vs. 42.8%) and FFWP (22.1 vs. 37.2%) treatments had reduced P/AI compared with cyclic cows, despite having similar or greater P4 concentration from study d -8 to -3, respectively. Estrus and ovulation synchronization protocols for lactating dairy cows must result in growth of ovulatory follicle under P4 concentration >2 ng/mL to ensure high P/AI.

Synchronisation of ovulation for management of reproduction in dairy cows

“…Bisinotto et al (2013) observed that incorporating Bisinotto, Ribeiro and Santos 154 two CIDR inserts during the timed AI protocol for cows without CL increased concentrations in plasma to 2.65 ng/mL and restored fertility similar to that of cows in dioestrus when the timed AI was initiated. Similar findings had been observed by Lima et al (2009b) and Denicol et al (2012). Therefore, when supplemental progesterone has to be used in high-producing cows, it is suggested that benefits to P/AI will be greater when the resulting concentrations of progesterone in blood resemble those of cows in dioestrus and, in some cases, two intravaginal devices are needed to achieve such concentrations.…”

“…Incorporation of intravaginal controlled internal drug release (CIDR) containing progesterone during presynchronisation did not result in significant changes in fertility (Chebel et al, 2006, Rutigliano et al, 2008. Overall, lactating dairy cows subjected to PGF 2α -based presynchronisation programmes had 42% greater odds of becoming pregnant compared with cows that did not receive any presynchronisation before the timed AI protocol (odds ratio (OR) = 1.42, 95% CI = 1.23 to 1.64; Bisinotto and Santos, 2012).…”

“…Unfortunately, the Ovsynch programme has limitations on its ability to synchronise follicle growth because ovulation to the initial GnRH administered at random stages of the oestrus cycle is usually 50% to 60%, or up to 70% when presynchronisation precedes the Ovsynch (Bisinotto and Santos, 2012;Ribeiro et al, 2012a). Even when cows were presynchronised with two sequential Ovsynch protocols (Double Ovsynch), ovulation to the first GnRH of the breeding Ovsynch was < 72% (Souza et al, 2008;Giordano et al, 2013).…”

“…Nevertheless, ovulation in response to the initial GnRH depends on the presence of a follicle responsive to LH. Because ∼70% of the lactating dairy cows have oestrus cycles with two follicular waves (Townson et al, 2002), treatment with GnRH at random stages of the oestrus cycle only induce ovulation in 50% to 60% of the cows (Bisinotto and Santos, 2012;Ribeiro et al, 2012a). Therefore, presynchronisation of the oestrus cycle has been developed to manage first postpartum AI such that synchronisation responses and P/AI to the Ovsynch protocol are optimised (Moreira et al, 2001).…”

“…Absence of a CL when the timed AI is initiated is a major limitation to high P/AI regardless whether the cow is anovular or not (Bisinotto et al, 2010a). It seems that a minimum of 2.5 to 3.0 ng/mL of progesterone during the Ovsynch protocol is needed for adequate fertility (Denicol et al, 2012;Bisinotto et al, 2013). Even when a CL is present, concentration of plasma progesterone in lactating cows is ∼1.5 ng/mL less than that of heifers (Sartori et al, 2004).…”