Reproductive performance of replacement dairy heifers submitted to first service with programs that favor insemination at detected estrus, timed artificial insemination, or a combination of both

Abstract

Our objective was to compare the insemination dynamics and time to pregnancy for up to 100 d after the beginning of the artificial insemination period (AIP) for heifers managed with first artificial insemination (AI) service programs that relied primarily on insemination at detected estrus (AIE) after PGF 2α treatments, timed artificial insemination (TAI), or a combination of both. Holstein heifers were randomly assigned to receive first AI service with sex-selected semen after 368 ± 10 d of age with (1) AIE after synchronization of estrus with up to 3 PGF 2α treatments every 14 d starting on the first day of the AIP (PGF+AIE; n = 317). Heifers not AIE up to 9 d after the third PGF 2α received a 5-d Cosynch protocol with progesterone supplementation [GnRH + controlled internal drug release insert (CIDR)-5 d-CIDR removal and PGF 2α-3 d-GnRH and TAI] before TAI. Heifers detected in estrus from CIDR removal and PGF 2α until the day before TAI received AIE with no GnRH treatment; (2) 2 PGF 2α treatments 14 d apart with the second treatment at the beginning of the AIP (PGF+TAI; n = 334). Heifers received AIE for up to 9 d after the second PGF 2α treatment. Heifers not AIE received TAI after the 5-d Cosynch protocol and (3) TAI after the 5-d Cosynch protocol (ALL-TAI; n = 315). Heifers failing to conceive to a previous AI received a subsequent AI with conventional semen at detected estrus or TAI after the 5-d Cosynch protocol. Binomial outcomes were analyzed by logistic regression, whereas time to AI and pregnancy were analyzed with Cox's regression. The hazard of first AI up to 45 d of the AIP was greater for ALL-TAI than for PGF+AIE

Effect of reproductive management programs for first service on replacement dairy heifer economics

“…Information about farms, animals, and experimental procedures are described in detail in Masello et al (2019). Briefly, nulliparous Holstein heifers from 2 commercial dairy farms located in New York State were enrolled in this experiment (Farm A located in Washington county and Farm B located in Wayne county), from November 2015 to February 2017.…”

“…This might be accomplished by implementing proactive reproductive management programs that maximize the insemination and conception risk after heifers reached the appropriate size to become pregnant. In this regard, Masello et al (2019) reported that a first service program designed to increase the insemination risk by using timed AI (TAI) after synchronization of ovulation with a 5d-Cosynch protocol for all heifers at the beginning of the AIP (i.e., ALL-TAI program) reduced time to pregnancy when compared with a program that relied on insemination after induction of estrus with up to 3 PGF 2α treatments every 14 d. In addition, a program that combined AI at detected estrus (AIE) for 9 d after 2 PGF 2α treatments 14 d apart and TAI for heifers not AIE resulted in similar time to pregnancy relative to the ALL-TAI program. Although results from this experiment suggested that programs that reduce days to first service with ALL-TAI or a combination of AIE and TAI might benefit heifer reproductive performance, ultimately the choice of program for most commercial farms should be based on economic outcomes for the heifer enterprise.…”

“…Thus, the primary objective of this study was to compare cash flow and parameters of economic performance for heifers enrolled in the experiment reported in Masello et al (2019). Specifically, our objective was to analyze individual heifer cash flow for a fixed period of time (i.e., 15 mo) after the beginning of the AIP.…”

Effect of One-Day Delaying CIDR Administration in 5-Day Cosynch Protocol in Dairy Heifers

“…Masello et al [ 27 ] reported similar the first service P/AI following TAI in 5-day CIDR-Cosynch protocol or combinations of AIE and TAI in 5-day CIDR-Cosynch protocol initiated nine days after presynchronization with two or three PGF2α administrations fourteen days apart in dairy heifers. Similarly, there was no main effect of presynchronization prior to both CIDR-4 and CIDR-5 groups in 5-day CIDR-Cosynch protocol in heifers although heifers were not allowed to be inseminated during presynchronization in current study.…”

Synchronization of Estrus and Ovulation in Dairy Cattle

“…More recently, a 5-day CIDR/CoSynch-72 program was shown to be more reliable (Figure 9) (Lima et al, 2009, Masello, 2019Rabaglino et al, 2010a;Rabaglino et al, 2010b;Rabaglino et al, 2010c). Pregnancy risk varies between 45 and 60%.…”