Pivotal periods for pregnancy loss during the first trimester of gestation in lactating dairy cows

Wiltbank, Milo C.; Baez, Giovanni M.; García-Guerra, A.; Toledo, Mateus Z.; Monteiro, P. L. J.; Melo, Leonardo de França e; Ochoa, Julián Camilo; Santos, J.E.P.; Sartori, Roberto

doi:10.1016/j.theriogenology.2016.04.037

Cited by 353 publications

(318 citation statements)

References 167 publications

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“…After breeding, whether natural or artificial, estrous repetition indicated that conception failed to occur or, if it has occurred, the cow experienced pregnancy loss. Conception failure and early pregnancy disruption are multicausal disorders originated by infectious, environmental, nutritional, or management factors (VANROOSE et al, 2000;WILTBANK et al, 2016). Our outcomes demonstrated that estrous repetition was more frequent in older animals (>6 years old).…”

mentioning

confidence: 69%

Repetition of estrus is the most frequent reproductive problem after breeding in dairy cattle from Rio de Janeiro, Brazil

et al. 2017

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Reproductive efficiency is one of the key elements for any milk production system to be successful. In this regard, reproductive management must be planned properly and the identification of the main reproductive disorders that affect the herd is primordial for decision-making. The aim of the present study was to identify the main reproductive problems that affect dairy herds on Rio de Janeiro (RJ), Brazil. Data regarding breed, age, reproductive disorder occurrence, and breeding system were individually collected from dairy cows raised at 25 farms located at RJ. The occurrence of reproductive disorders was reported in 37% of the studied animals. Estrous repetition (76.2%) and abortion (15.6%) were the most frequent reproductive problems reported. Estrous repetition was more common in older animals (>6 years old). However, an association between abortion and age of animal was not observed, nor an association between breeding system and occurrence of abortion. The present results demonstrated that estrous repetition is the main obstacle to the reproductive efficiency in dairy herds at RJ, and that the replace of older cows by heifers is an important point within reproductive management of a dairy herd.

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mentioning

confidence: 69%

Repetition of estrus is the most frequent reproductive problem after breeding in dairy cattle from Rio de Janeiro, Brazil

et al. 2017

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“…Related to this question is the observation of pregnancy loss during 30-60 days of pregnancy. For example, we recently summarized the results from 46 recent studies and ~25,000 pregnancies that were evaluated by ultrasound on ~day 32 and again at ~day 60 and found 11.95% pregnancy loss during this period (Wiltbank et al, 2016). The pregnancy loss during this time period is even greater for clones.…”

Section: Period III Prevention Of Later Luteolysis During Pregnancymentioning

confidence: 99%

“…We became more interested in luteolysis during this time period, based on recent observations that we made on timing of CL regression in accessory CL that are contralateral to the pregnancy (Wiltbank et al, 2016). In this experiment, we induced accessory CL in lactating cows by treatment with GnRH on day 5 after AI.…”

Section: Period III Prevention Of Later Luteolysis During Pregnancymentioning

confidence: 99%

Maintenance or regression of the corpus luteum during multiple decisive periods of bovinepregnancy

Wiltbank¹,

Meidan²,

Ochoa³

et al. 2016

Anim Reprod

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In ruminants, there are specific times during the estrous cycle or pregnancy when the corpus luteum (CL) may undergo regression. This review has attempted to summarize the physiological and cellular mechanisms involved in CL regression or maintenance during four distinct periods. The first period is near day 7 when animals that are ovulating after a period of low circulating progesterone (P4), such as first pubertal ovulation or first postpartum ovulation, are at risk of having a premature increase in Prostaglandin F2α (PGF) secreted from the uterus resulting in early CL regression and a short estrous cycle. The second period is when normal luteolysis occurs at day 18-25 of the cycle or when the CL is rescued by interferon-tau secreted by the elongating embryo. The uterine mechanisms that determine the timing of this luteolysis or the prevention of luteolysis have been generally defined. Induction and activation of endometrial E2 receptors result in induction of endometrial oxytocin receptors that can now be activated by normal pulses of oxytocin. Of particular importance is the observation that the primary mechanisms are only activated through local (ipsilateral) and not a systemic route due to transfer of PGF from the uterine vein to the ovarian artery. In addition at the CL level, studies are providing definition to the cellular and molecular mechanisms that are activated in response to uterine PGF pulses or pregnancy. The third period that is discussed occurs in the second month of pregnancy (day 28-60) when undefined mechanisms result in CL maintenance of an ipsilateral CL but regression of a contralateral (opposite side from pregnancy) CL. The final period that is discussed is regression of the CL just prior to parturition. Although, cortisol from the fetus appears to be the primary initiator of luteolysis, PGF seems to be the final signal that causes regression of the CL. Thus, in all four periods, regression of the CL is likely to be caused by the direct actions of PGF that is secreted from the uterus. The uterine mechanisms that result in secretion of PGF seem to be normally inhibited during the early luteal phase, making short luteal phases not a normal event, and are altered during early pregnancy (day 18-25) resulting in prevention of luteolysis. During much of pregnancy, the mechanisms that cause PGF secretion from the uterus in response to oxytocin are intact but luteolysis does not normally occur, perhaps due to lack of efficient utero-ovarian transfer of PGF.

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“…Since then, that terminology has been used worldwide to define embryo losses. Recently, some authors (Walsh et al, 2011, Wiltbank et al, 2016 have proposed some modifications to define embryo mortality based on the crucial periods that the embryo faces within the reproductive tract to establish a successful full-term pregnancy. Thus, Walsh et al (2011) suggested including an initial stage termed very early embryo mortality to define the losses that occur after breeding and within the first week of gestation.…”

Section: Embryo Mortality and Endometrial Receptivitymentioning

confidence: 99%

63 Effect of Endometrial Biopsy on Uterine Health of Tropically Adapted Beef Cattle

Ramirez-Garzon

Satake

Lyons

et al. 2017

Reprod. Fertil. Dev.

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In cattle, early embryonic loss during the first two to three weeks after fertilisation is recognised as the major cause of reproductive failure, with consequent significant impacts on business performance of beef and dairy farms. Inadequate endometrial receptivity is considered an important cause of early embryonic mortality in cattle. A pilot experiment was conducted to compare the outcome of performing different endometrial sampling procedures in tropically adapted (Bos indicus x Bos taurus) heifers, and to select the most suitable method to collect samples for investigation of endometrial gene expression. Endometrial biopsy (EB) using a biopsy device with a diameter similar to an artificial insemination gun (10366L Karl Storz®, Germany) was found to be the most reliable method of collecting endometrial samples in these heifers, with the samples recovered yielding a mean concentration of RNA of 72.9 ±39.3 ng/µl and mean RNA integrity number (RIN) of 7.3 ±1.1.To assess the likely safety of conducting EB in cattle a systematic review of published information assessing the impact of EB on subsequent pregnancy rates was conducted. Using the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) protocol, online searches identified 1164 possible studies. After applying the exclusion criteria, six studies allowed the comparison of pregnancy rates between sampled (n= 1,208) and non-sampled cows (n=2,393). The results showed that EB can be performed before breeding without adversely affecting the likelihood of cows becoming pregnant.A major objective of the research was to determine whether EB and evaluation of endometrial gene expression could be used to identify tropically adapted embryo transfer (ET) recipients more likely to become pregnant. Three potential EB scenarios were investigated, 1) EB on Day 7 of the oestrous cycle prior to the cycle when ET would be performed, 2) EB on Day 4 of the oestrous cycle in which ET would be performed i.e. EB 3 days before ET, and 3) EB on the same day when ET would be performed.The first study assessed the morphological and inflammatory changes induced by endometrial biopsy. Pre-synchronised heifers underwent EB from the horn ipsilateral to the corpus luteum (CL) either at Day 7 of the previous cycle (Group 1 n=10) followed by administration of a luteolytic dose of prostaglandin F2α or at Day 4 (Group 2, n=7) of the present cycle. All heifers were slaughtered on Day 7 of the present cycle. The site of EB was visually evident in 40% (4/10) of Group 1 and 42% (3/7) of Group 2 heifers. Histological assessment revealed no evidence of changes indicative of endometritis in either the biopsied or non-biopsied horns in both groups. The histological iii changes observed included mild mononuclear infiltration of the epithelium and mild vascular changes associated with haemorrhage and congestion.Initial investigation of the endometrial expression of the pro-inflammatory cytokine IL1β and wound healing cytokine TGFβ genes found no significant difference betwe...

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Pivotal periods for pregnancy loss during the first trimester of gestation in lactating dairy cows

Cited by 353 publications

References 167 publications

Repetition of estrus is the most frequent reproductive problem after breeding in dairy cattle from Rio de Janeiro, Brazil

Repetition of estrus is the most frequent reproductive problem after breeding in dairy cattle from Rio de Janeiro, Brazil

Maintenance or regression of the corpus luteum during multiple decisive periods of bovinepregnancy

63 Effect of Endometrial Biopsy on Uterine Health of Tropically Adapted Beef Cattle

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