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A 60% pregnancy success for inseminations is targeted to optimize production efficiency for dairy cows within a seasonal, pasture-grazed system. Routine measures of pregnancy success are widely available but are limited, in practice, to a gestation stage beyond the first 28 d. Although some historical data exist on embryonic mortality before this stage, productivity of dairy systems and genetics of the cows have advanced significantly in recent decades. Accordingly, the aim was to construct an updated estimate of pregnancy success at key developmental stages during the first 70 d after insemination. Blood samples were collected for progesterone concentrations on d 0 and 7. A temporal series of 4 groups spanning fertilization through d 70 were conducted on 4 seasonal, pasture-grazed dairy farms (n = 1,467 cows) during the first 21 d of the seasonal breeding period. Morphological examination was undertaken on embryos collected on d 7 (group E7) and 15 (group E15), and pregnancy was diagnosed via ultrasonography on approximately d 28 and 35 (group E35) as well as d 70 (group E70). Fertilization, embryo, and fetal evaluation for viability established a pregnancy success pattern. Additionally, cow and on-farm risk factor variables associated with pregnancy success were evaluated. We estimated pregnancy success rates of 70.9%, 59.1%, 63.8%, 62.3%, and 56.7% at d 7, 15, 28, 35, and 70, respectively. Fertilization failure (15.8%) and embryonic arrest before the morula stage (10.3%) were the major developmental events contributing to first-week pregnancy failures. Embryo elongation failure of 7% contributed to pregnancy failure during the second week. The risk factors for pregnancy success that were related to the cows included interval between calving and insemination, and d-7 plasma progesterone concentrations, whereas insemination sire was associated with pregnancy outcome. Most pregnancy failure occurs during the first week among seasonal-calving pasture-grazed dairy cows. [Display omitted] [ABSTRACT FROM AUTHOR]

Recessive alleles represent genetic risk in populations that have undergone bottleneck events. We present a comprehensive framework for identification and validation of these genetic defects, including haplotype-based detection, variant selection from sequence data, and validation using knockout embryos. Holstein haplotype 2 (HH2), which causes embryonic death, was used to demonstrate the approach. Holstein haplotype 2 was identified using a deficiency-of-homozygotes approach and confirmed to negatively affect conception rate and stillbirths. Five carriers were present in a group of 183 sequenced Holstein bulls selected to maximize the coverage of unique haplotypes. Three variants concordant with haplotype calls were found in HH2: a high-priority frameshift mutation resulting, and 2 low-priority variants (1 synonymous variant, 1 premature stop codon). The frameshift in intraflagellar 80 (IFT80) was confirmed in a separate group of Holsteins from the 1000 Bull Genomes Project that shared no animals with the discovery set. IFT80-null embryos were generated by truncating the IFT80 transcript at exon 2 or 11 using a CRISPR-Cas9 system. Abattoir-derived oocytes were fertilized in vitro, and zygotes were injected at the one-cell stage either with a guide RNA and CAS9 mRNA complex (n = 100) or Cas9 mRNA (control, n = 100) before return to culture, and replicated 3 times. IFT80 is activated at the 8-cell stage, and IFT80-null embryos arrested at this stage of development, which is consistent with data from mouse hypomorphs and HH2 carrier-to-carrier matings. This frameshift in IFT80 on chromosome 1 at 107,172,615 bp (p.Leu381fs) disrupts WNT and hedgehog signaling, and is responsible for the death of homozygous embryos. [ABSTRACT FROM AUTHOR]

Endometrial epidermal growth factor (EGF) shows a cyclic change with two peaks on Days 2–4 and 13–14 during the estrous cycle. An altered (i.e., loss of the two peaks) profile has been linked to reduced fertility in repeat breeder cows. We previously demonstrated that a form of osteopontin (OPN), with a molecular weight of 29 kDa and found in bull seminal plasma (SP), normalized the EGF profile and restored fertility in repeat breeder cows. OPN has many molecular forms due to post-translational modifications and is abundant in bovine milk. The purpose of the present study was to investigate whether mOPN normalizes the endometrial EGF profile and restores fertility in repeat breeder dairy cows with an altered EGF profile. OPN was separated by one-step anion-exchange column chromatography from the whey of bovine milk. Purified mOPN was verified by Western blotting and peptide mass fingerprinting analyses. The OPN fraction showed three major protein bands of 61, 37 and 31 kDa (peptides I, II, and III, respectively) on SDS-PAGE. All three major bands were identified as OPNs by Western blotting and their tryptic peptide masses were matched at approximately 50, 40, and 10%, respectively, to the bovine OPN amino acid sequence by a peptide mass finger printing analysis. The three bands accounted for approximately 85% of the total protein content and 6–23 mg of OPN was obtained from 1 L of bovine milk. A lyophilized eluate containing 1.3 mg of mOPN (171 cows), 0.5 mL of frozen SP (62 cows), and PBS (84 cows) was infused at estrus into the vagina of repeat breeder cows with an altered EGF profile. Some of the cows treated with mOPN, SP, and PBS (46, 50, and 45 cows, respectively) were inseminated immediately before the infusion and then examined for pregnancy between Days 60 and 65. The rate at which mOPN to normalize the EGF profile (56.1%) was similar to that of SP (58.1%) and higher than that of PBS (23.8%) (P < 0.05). The conception rate after the infusion of mOPN (43.5%) was similar to that of SP (40.0%) and higher than that of PBS (22.2%) (P < 0.05). The present results indicate that the infusion of mOPN into the vagina is a treatment option for repeat breeder cows with an altered EGF profile. Further studies are needed to compare the capacity of the three OPN molecules in milk to normalize the EGF profile, together with their molecular characteristics due to post-translational modifications. • OPN protein (mOPN) between 6 and 23 mg from 1 L of milk and with three different molecular masses are obtained. • mOPN normalized the endometrial EGF profile and restored fertility in repeat breeder dairy cows. • The effects of mOPN are at the similar levels to seminal OPN despite different molecular masses of OPNs in the two sources. [ABSTRACT FROM AUTHOR]

A greater understanding of factors influencing fertility is essential to improve pregnancy rates and reduce the occurrence of embryonic mortality in beef herds. The objective of the current study was to evaluate retrospective data of pregnancy per artificial insemination (P/AI) and pregnancy loss in Nelore females subjected to timed-AI (TAI) in Brazil. Data from 40,104 TAI collected from six breeding seasons (2016–2022) were analyzed, and the effects of animal category (e.g., classification based on age and parity), farm, month of parturition, sire, sire breed (Nelore vs Angus), estrus expression at TAI, animal temperament, and body condition scores (BCS) were evaluated. P/AI and pregnancy loss were affected (P < 0.001) by animal category. There was also an effect of farm (P = 0.0013) on P/AI and pregnancy loss (P = 0.001), as P/AI ranged from 49.28% and 55.58% and pregnancy loss from 3.37% to 6.89% across the herds evaluated. Month of parturition also affected (P < 0.001) P/ AI and was higher for cows that became pregnant at the beginning of the previous breeding season. Calmer animals, presenting lower velocity scores while exiting the chute following TAI, achieved higher P/AI (P < 0.001). Lower BCS at TAI was associated (P < 0.001) with increased pregnancy loss, and BCS gain following AI was associated (P < 0.001) with reduced rates of embryonic mortality. There was a major effect (P < 0.001) of sire on P/AI and pregnancy loss, as P/AI ranged from 11% to 79%, and embryonic mortality from 0% to 40% for the bulls used in the study, highlighting the importance of the sire fertility on overall pregnancy success. Results from the current study reinforce the idea that animal age and parity at the beginning of the breeding season, BCS at the onset of estrous synchronization, BCS gain following AI, estrus expression at TAI, sire, and month of parturition are important factors influencing P/AI and rates of embryonic mortality in beef herds. • Factors like Farm, Sire Breed, bull, Dam Category, BCS, parturition month, and Heat influence pregnancy loss in Nellore cows. • The pregnancy rate at TAI didn't correlate with pregnancy loss. • P/AI vary from 11% to 79% according to bull. • Pregnancy loss varies from 0% to 40% according to bull [ABSTRACT FROM AUTHOR]

What is the impact of radiation exposure on oocyte quality and female fertility? Prepubertal mice underwent whole-body irradiation with a single dose (0.02, 0.1, 0.5, 2, 8 Gy) of gamma- or X-rays. Oocytes were quantified in irradiated (n = 36) and sham-treated (n = 8) mice. After a single exposure to 2 Gy, formation of DNA double-strand breaks (n = 10), activation of checkpoint kinase (Chk2) (n = 10) and dynamics of follicular growth (n = 18) were analysed. Fertility assessment was performed in adult irradiated mice and controls from the number of pups per mouse (n = 28) and the fetal abortion rate (n = 24). Ploidy of mature oocytes (n = 20) was analysed after CREST immunostaining, and uterine sections were examined. Radiation exposure induced a massive loss of primordial follicles with LD 50 below 50 mGy for both gamma and X-rays. Growing follicles survived doses up to 8 Gy. This difference in radiosensitivity was not due to a different amount of radio-induced DNA damage, and Chk2 was activated in all oocytes. Exposure to a 2 Gy dose abolished the long-term fertility of females due to depletion of the ovarian reserve. Detailed analysis indicates that surviving oocytes were able to complete folliculogenesis and could be fertilized. This transient fertility allowed irradiated females to produce a single litter albeit with a high rate of fetal abortion (23%, P = 0.0096), related to altered ploidy in the surviving oocytes (25.5%, P = 0.0035). The effects of radiation on surviving oocyte quality question natural conception as a first-line approach in cancer survivors. Together, the data emphasize the need for fertility preservation before radiation exposure and call for reassessment of the use of cryopreserved oocytes. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the association between reproductive disorders and the main serogroups of Leptospira spp. in dairy herds. Blood samples from 216 cows from nine herds were collected for a Microscopic Agglutination Test (MAT), and a reproductive follow-up with ultrasonography was carried out monthly for at least 12 months. A total of 75 (16.5%) cows were reactive, while seroreactivity to a herd level ranged from 16.0% to 52.8%. Out of the nine herds, in five (55.0%) Sejroe was found to be the predominant serogroup and in four (45.0%) it was Icterohaemorrhagiae. The major reproductive problems identified were embryonic death (ED) and abortions. All herds presented ED and abortion was observed in three (33.3%). Herds with high seroreactivity (>20%) had more reproductive problems. Those with a predominance of Sejroe were associated with ED (P < 0.05), while those with Icterohaemorrhagiae were associated with abortion. The results show that different leptospiral strains lead to different reproductive problems, as well as showing that the main problem – ED – is caused by leptospirosis, particularly for those determined by strains of the serogroup Sejroe. • Bovine leptospirosis is reproductive disease and leads to reproductive disorders (ED, repetitive estrous, Abortion). • Cattle herds with high seroreactivity to leptospiral serogroups had more reproductive disorders. • Seroreactivity to Leptospira spp. strains of Sejroe serogroup was associated to embryonic death. • Seroreactivity to Icterohaemorrhagiae strains was associated to abortions. [ABSTRACT FROM AUTHOR]

Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure. [ABSTRACT FROM AUTHOR]

The feeding of diets with greater energy content than that needed for body maintenance following mating is believed to reduce embryonic survival in pigs. In swine operations, therefore, feed intake is often restricted during the first and second week of pregnancy to reduce embryo mortality. There is thought to be a relationship between feeding diets that result in energy intake that is greater than that needed for body maintenance and embryonic death. This relationship is associated with lesser than typical progesterone (P4) concentrations when feeding diets with greater energy content due to increased hepatic clearance. There is no consensus, however, as to whether feeding should be restricted during early pregnancy to avert this possible detrimental effect. Thus, the aim of this systematic review is to assess the effect in sows and gilts of feeding diets with different energy contents post-mating on embryonic survival, evaluating when possible, the relationship of a greater energy intake and P4 concentrations on embryonic survival. An electronic search was conducted of the PubMed, Science Direct, Scopus, Web of science, and Scielo databases during June 2018. A total of 109 articles were retrieved, and of these, only 16 articles were selected after applying the selection criteria. There was no negative effect of a greater feed intake than that needed for body maintenance after breeding in 75% of the experiments. Results from 35% of the experiments indicated feeding early pregnant sows a diet with greater energy content than that needed for body maintenance resulted in augmented embryonic death. In 66.7% of the experiments, in which there was assessment of P4 concentration, there was no negative effect of feeding after farrowing a diet with greater energy than that needed for body maintenance. In conclusion, it appears that restricted feed intake in early pregnancy is no longer relevant when there are modern prolific dam lines utilized in swine production enterprises because dietary energy of as great as 54 MJ ME/day had no detrimental effect on embryo survival. [ABSTRACT FROM AUTHOR]

Abstract The goal of this study was to evaluate the effect of long-acting progesterone supplementation on pregnancy rates and gestational losses in Nelore females (Bos taurus indicus) submitted to Timed Artificial Insemination (TAI). Ovulations of multiparous (n = 534), primiparous (n = 117) and nulliparous (n = 81) Nelore females were synchronized for TAI and the day of insemination was considered D0. After TAI, the animals were allocated into three groups. Two groups received 150 mg of long acting injectable progesterone (P4) in a single dose, 5 (D = 5) or 11 (D = 11) days after TAI, resulting in the following treatments: 1) Group P4 - D5 (n = 235); 2) Group P4 - D11 (n = 245); and 3) Control Group (n = 252). The animals in the control group did not receive any supplementation. Pregnancy was checked by ultrasonography, 30 days after the TAI. The gestational losses were evaluated at two different periods: 1) from 30 to 60 days, and 2) from 60 to 90 days. The pregnancy rate and the gestational losses as a function of the treatments were tested by the non-parametric binomial test with 5% significance level. The pregnancy rates were different between the groups P4 - D5 and Control (47 and 39%, respectively) (P < 0.05), but no difference was observed in relation to the P4 - D11 group. There was a difference in gestational losses from 30 to 60 days and total losses between the groups treated with P4 on the fifth day and eleventh day after TAI in relation to the control group (P = 0.0173; P = 0.0454), but no difference was observed between the treatments in relation to the losses between 60 and 90 days (P ≥ 0.0578). Among the animals that were cycling at the beginning of the protocol, the groups supplemented with progesterone at day 5 or 11 after insemination had gestational losses significantly lower (P = 0.04) than the control group (P4 - D5 = 2%; P4 - D11 = 2%, control = 14%). The animals in anestrous that received supplementation 5 days after TAI had lower gestational losses (P = 0.049) compared with the other groups (P4 - D5 = 3%, P4 - D11 = 7% Control = 10%). Under the conditions of this study, the use of long-acting injectable progesterone 5 days after TAI in Nelore females increased the pregnancy rates, but when supplemented 11 days after TAI, it did not have the same effect. Also, when used 5 days after TAI, it significantly decreased gestational losses on both anestrous and cycling animals. Therefore, it may be an interesting alternative to increase reproductive and productive efficiencies. Highlights • Pregnancy losses from 30 to 60 days were significant different between treated groups. • There was difference (P = 0.049) in pregnancy losses considering cyclicity. • For anestrous animals, control group presented pregnancy losses higher than P4-D5. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of a single administration of one of three different gonadotropins on Day 7 post-insemination on ovarian activity, progesterone (P 4 ) concentration and pregnancy outcomes of rabbit does. Multiparous, non-lactating, V-line does were artificially inseminated after synchronization and ovulation induction with equine chorionic gonadotropin (eCG; 25 IU im) and gonadotropin releasing hormone (GnRH; 0.8 μg buserelin im) 48 h later. On Day 7 post-inseminarion, does were randomly allocated into four groups (n = 40/group). Does of each group were intramuscularly injected with a single dose of one of physiological saline ( placebo ; control), GnRH (0.8 μg buserelin), human chorionic gonadotropin (hCG; 25 IU) or eCG (25 IU). Concentration of serum P 4 was determined on Days 6, 9, 11 and 18 post-insemination. On Day 14 post-insemination, the ovaries and reproductive tracts of pregnant does were removed and weighed. Also, numbers of visible follicles, hemorrhagic follicles, corpora lutea of pregnancy (pCLs), new CLs (nCLs; formed after Day 7 post-insemination) and implantation sites were recorded. Conception rate, parturition rate, abortion rate, litter size/weight and litter viability were recorded. The highest (P < 0.05) reproductive tract and ovary weights were for eCG. The highest (P < 0.05) number of visible ovarian follicles was for eCG, whereas the lowest (P < 0.05) was for GnRH. Treatment with eCG increased (P < 0.05) numbers of pCLs and total implantation sites compared to the other groups. Treatment with GnRH or hCG increased (P < 0.05) number of nCLs compared to control and eCG. The highest rate of fetal loss was in does treated with GnRH. The concentration of serum P 4 decreased (P < 0.05) following the treatment with GnRH and continued low until Day 18. However, it remained in line for control, hCG and eCG groups up to Day 11, then decreased (P < 0.05) for control and hCG on Day 18, being lower for hCG than control, while continued to increase for eCG up to Day 18. Compared to control, treatment with eCG improved (P < 0.05) conception and parturition rates by 24 and 22%; respectively, while GnRH and hCG treatments decreased (P < 0.05) them by 57 and 47.6%; respectively. Litter size and litter weight at birth were improved by eCG, but were adversely affectd by GnRH and hCG. In conclusion, a single administration of eCG 7 Days post-insemination could be recommended for improving pregnancy outcomes in rabbits. [ABSTRACT FROM AUTHOR]

Defining factors associated with embryonic and/or fetal losses will be helpful in overcoming such problem, either by adjusting conditions or applying therapeutic approaches to high-risk cows. The objective of this study was to investigate the association between a number of maternal and non-maternal factors and the risk of late embryonic (LED) and early fetal death (EFD) in dairy herds. Additionally, we investigated the effect of treating pregnant cows either with GnRH on day 26 post-insemination, or GnRH on day 26 plus CIDR insertion between days 26 and 33 post-insemination, on the risk of LED/EFD. From 3826 pregnancies, diagnosed at day 30 post-insemination, 851 cows lost the pregnancy by day 70 post-insemination. A mixed-effects logistic model was constructed to assess the effect of cow breed, calving difficulty, postpartum problems, lactation number, days in milk, insemination number, actual 305-day milk production, temperature humidity index (THI) at insemination, estrus synchronization protocols, and other factors, on the risk of LED/EFD. Our findings indicated that Holstein X Brown Swiss crossbreed cows had a lower risk for LED/EFD than Holstein cows (P < 0.05). Cows that had postpartum problems, were inseminated for the first time, produced more milk, or were inseminated at THI ≥75, recorded higher risks of LED/EFD (P < 0.05). Calving difficulty, lactation number, and synchronization protocols were not found to be associated with LED/EFD. Moreover, treatment of the pregnant cows with GnRH on day 26 post-insemination plus CIDR insertion between days 26 and 33 post-insemination decreased the risk of LED/EFD. In conclusion, cows that had postpartum problems, were inseminated early postpartum, produced higher milk, and/or were inseminated at high THI, were under higher risk of LED/EFD. Treating such cows with GnRH on day 26 plus CIDR insertion between days 26 and 33 may decrease the possibility of the LED/EFD. [ABSTRACT FROM AUTHOR]

Early pregnancy loss occurs in 6-10% of equine pregnancies making it the main cause of reproductive wastage. Despite this, reasons for the losses are known in only 16% of cases. Lack of viable conceptus material has inhibited investigations of many potential genetic and pathological causes. We present a method for isolating and culturing placental cells from failed early equine pregnancies. Trophoblast cells from 18/30 (60%) failed equine pregnancies of gestational ages 14-65 days were successfully cultured in three different media, with the greatest growth achieved for cells cultured in AmnioChrome™ Plus. Genomic DNA of a suitable quality for molecular assays was also isolated from 29/30 of these cases. This method will enable future investigations determining pathologies causing EPL. [ABSTRACT FROM AUTHOR]

Abstract: Pregnancy loss in mares is thought to be a main problem associated with reproductive efficiency. To clarify the situation of pregnancy loss in Thoroughbred mares in Japan, the occurrence of pregnancy loss before and after 35 days of gestation was investigated with 1,476 Thoroughbred mares in Hidaka, Japan, from 2007 to 2009. Pregnancy loss on days 17-35 was determined by ultrasound examination between 17 and 35 days after the last mating. Follow-up surveys were conducted between 35 days and foaling to determine pregnancy loss on day 35 until foaling in 843 of these mares. Using multiple logistic regression analysis, we assessed the influence of mare age, reproductive status, twin pregnancy reduction, body condition score (BCS), estrus type in foaling mares (foal heat or not), progesterone therapy, and endometrial cysts on pregnancy loss rates on days 17-35 and on day 35 until foaling in this population of mares. The pregnancy loss rates on days 17-35 and on day 35 until foaling were 5.8% and 8.7%, respectively. The overall pregnancy loss rate (day 17 until foaling, including parturient losses) was 14.7%. Risk factors for pregnancy loss included decrease in BCS between 17 and 35 days, <5 BCS at day 35, mating during foal heat, and endometrial cysts. In all, 14.7% of pregnancies were lost between day 17 and birth, contributing significantly to reduced reproductive efficiency in Thoroughbred mares in Japan. These observations indicate that mares should be maintained at high BCS and should be prevented from mating in foal heat to decrease the pregnancy loss rates. [Copyright &y& Elsevier]

Abstract: Bottlenose dolphins (Tursiops truncatus) undergoing natural breeding and artificial insemination (AI) were examined to characterize serum progesterone concentrations and determine relationships among age, parity, and reproductive outcome. Progesterone profiles of five cycle types (n = 119 total cycles from 54 animals) were characterized as follows: (i) conception and production of a live term calf (conceptive-term, n = 73); (ii) conception and abortion after Day 60 (conceptive-abortion, n = 12); (iii) unknown conception status with prolonged, elevated progesterone and absence of a fetus (conceptive-unknown, n = 14); (iv) conception failure with normal luteal phase progesterone concentrations (non-conceptive, n = 14, AI cycles only); and (v) conception failure with progesterone insufficiency occuring after spontaneous ovulation or owing to premature ovulation induction using GnRH (non-conceptive-PI, n = 6, AI cycles only). By Day 21 post-insemination (PI), progesterone concentrations were similar (P > 0.05) among conceptive-term, conceptive-abortion and conceptive-unknown, and higher (P < 0.05) for conceptive-term than non-conceptive and non-conceptive-PI cycles. Progesterone concentrations of known conceptive cycles peaked by Week 7 PI (P < 0.05) and remained elevated for the remainder of pregnancy (Weeks 8 up to 54, ≥5 days pre-partum). During midpregnancy (Days 121–240), conceptive-term cycles had higher (P > 0.05) progesterone concentrations than conceptive-abortion and unknown conception status cycles. Parity was not associated with reproductive outcome based on cycle type (P > 0.05). Age of females in conceptive-unknown (26.5 ± 10.1 yrs) and conceptive-abortion (22.1 ± 9.4 yrs) groups was higher (P < 0.05) than in conceptive-term (15.7 ± 7.2 yrs). The conceptive-unknown cycle type possibly represents undetected early embryonic loss occurring before Day 60 PI. Length of gestation using known conception dates was 376.1 ± 11.0 days and the range of this parameter (355–395 days) has implications for peri-parturient management procedures for the species. [Copyright &y& Elsevier]

Abstract: The objective was to compare the observed and expected combined effects of clinical mastitis before timed artificial insemination (TAI) and low body condition at 70 d postpartum (dpp) on pregnancy loss in dairy cows. Cows were examined for pregnancy by ultrasonographic examination 28–32 d after TAI; the presence of an embryo with a heartbeat was the criterion used to determine pregnancy. Cows diagnosed pregnant were re-examined by transrectal palpation of the uterus and its contents 28 d later to confirm pregnancy status and to identify pregnancy loss. Eighty-eight (17%) of 512 cows were diagnosed with pregnancy loss. Cows affected with clinical mastitis before insemination and a body condition score (BCS) ≤ 2.75 at 70 dpp were 2.03 times more likely to experience pregnancy loss, compared to cows without clinical mastitis and with a BCS > 2.75 (RR = 2.03; 95% CI = 1.15, 3.60; P = 0.01). This observed combined effect for pregnancy loss (RR = 2.03) was higher than the expected combined effect based on adding (RR = 1.39) or multiplying (RR = 1.42) absolute independent excesses due to clinical mastitis or low body condition. [Copyright &y& Elsevier]

Abstract: The objective was to determine physiological causes of low fertility in beef cows. Fertility was compared between low-fertility cows (34 British cows and 64 Brahman crossbred cows; cows that did not get pregnant when mated to fertile bulls in one or two previous breeding seasons); fertile cows (16 Brahman crossbreds; cows having a calf in several of the preceding breeding seasons), and virgin heifers (45 Brahman crossbreds, 2 yr of age). Females were mated to fertile bulls and killed 3 or 34 d after breeding to obtain reproductive tracts. There were no significant differences among groups in rates of ovulation or fertilization. Overall, 14% of females failed to ovulate and 24% that ovulated failed to undergo fertilization. The proportion of cows that were not detected in estrus before Day 34 of pregnancy was lower (P<0.01) for low-fertility British cows (5 of 16 cows, 31%) than for other groups, including low-fertility Brahman crossbred cows (23/32, 72%), fertile cows (8/9, 89%), and heifers (21/24, 88%). All cows that did not return to estrus by Day 34 had an identifiable conceptus. The proportion of conceptuses recovered at Day 34 that were classified as normal (weight and length) was lower (P<0.05) for cows with low fertility (British: 2/5, 40%; Brahman crossbred: 9/23, 39%) than for fertile cows (8/8, 100%) or heifers (18/21; 86%). Similarly, the proportion of cows in which a normal embryo was recovered (cows with normal embryos/number of cows mated) was lower (P<0.001) for low-fertility British cows (2/16, 13%) and low-fertility Brahman crossbred cows (9/32, 28%) than for fertile cows (8/9, 89%) and heifers (18/24, 75%). In conclusion, cows that were infertile in previous breeding seasons did not experience reduced ovulation or fertilization rates, but had greater embryonic mortality. These data highlighted the importance of ovulation and fertilization failure and embryonic mortality as important determinants of pregnancy success. Moreover, increased embryonic loss after Day 34 contributed to infertility in low-fertility cows. [Copyright &y& Elsevier]

Abstract: The objective was to estimate the effect of palpation per rectum (for early pregnancy diagnosis) on embryo/fetal viability in dairy cattle. A controlled, randomized block-design experiment with two blocks, one by category, and the other by number of embryos, was conducted. Five-hundred-and-twenty pregnant dairy cows and heifers with a viable embryo detected by transrectal ultrasonography (TRUS) between days 29 and 32 after AI were included. The pregnant females were randomly allocated into two nearly equal groups: palpation per rectum (PAL group; n =258) and no palpation per rectum (NPAL group; n =262). The PAL group was submitted to palpation per rectum (PPR) using the fetal membrane slip (FMS) technique once between days 34 and 41 of pregnancy. The fetal membrane slip consisted of compressing the pregnant uterine horn and allowing the chorioallantoic membrane to slip between the fingers. Both groups were submitted to two additional TRUS at days 45 and 60 of pregnancy, to monitor the potential immediate and delayed deleterious effects of PPR on embryo and fetal viability, respectively. A diagnosis of embryo/fetal death was made when there was no embryo/fetal heart beat or the absence of positive signs of pregnancy in an animal previously diagnosed pregnant, or the presence of signs of embryo/fetal degeneration. The overall rate of embryo/fetal death was 14.0% (73/520). Embryonic death (10%; 52/520) was higher than fetal death (4.5%; 21/468; P <0.001). Embryo/fetal mortality was higher in cows (16.4%; 59/360) than in heifers (8.8%; 14/160; P <0.025) and in cattle with twin (25.5%; 12/47) versus singleton pregnancies (12.9%; 61/473; P <0.025), but was not different (P >0.05) between PAL (14.7%; 38/258) and NPAL (13.4%; 35/262). In conclusion, PPR between days 34 and 41 of pregnancy using the fetal membrane slip technique did not affect embryo/fetal viability. [Copyright &y& Elsevier]

Abstract: Objectives: To compare early loss rates between twin and singleton pregnancies following ART. Study design: First-trimester sonography counted the number of embryos with positive heartbeat in women undergoing IVF/ICSI and transfer of one to three embryos. The number of lost pregnancies was calculated from a second-trimester sonogram. Loss rates of the entire pregnancy were related to maternal age <38 or ≥38 years, IVF or ICSI, and cleavage or blastocyst stage embryo transfers (in ICSI cases). Results: Patients underwent IVF with (n =672) and without (n =189) ICSI. The overall odds of miscarrying the entire singleton pregnancy were 2.6 times that of a twin gestation (95% CI 1.5, 4.5). The disadvantage for singletons compared to twins seems more apparent in pregnancy after ICSI in the subgroup of patients <38 years (OR 2.9, 95% CI 1.5, 5.8). In this subgroup, the disadvantage conferred to singletons appeared only among days 2–3 embryo transfers (OR 3.0, 95% CI 1.3, 7.2). Conclusion: A significantly lower early spontaneous loss rate of twin pregnancies seems related to ICSI followed by cleavage stage embryo transfer in patients <38 years. [Copyright &y& Elsevier]

Abstract: The objective of the experiment was to determine the effects of fat supplementation on cyclicity, progesterone concentration, follicular development, conception rate, embryo mortality, and plasma concentrations of prostalglandin F metabolite (PGFM) in cattle. The hypothesis of this experiment was that feeding flaxseed, which is a source rich in C18:3, would increase conception rate of dairy cows due to decreased plasma PGFM concentrations. A total of 138 lactating Holstein cows were allotted at calving to three groups of 46 cows, blocked for similar calving dates. Cows within each block were assigned to one of three isonitrogenous, isoenergetic, and isolipidic supplements based on either whole flaxseed (FLA), Megalac® (MEG) or micronized soybeans (SOY). The diets were fed from calving to Day 50 of pregnancy for pregnant cows, or 120 day postpartum for those not diagnosed pregnant after AI. Detailed measurements of PGFM and follicle dynamics were only made on four cows for FLA and five cows for both MEG and SOY. The response in PGFM concentration following the oxytocin challenge administered around Week 11 of lactation was similar over time among treatments. Plasma progesterone concentrations from Days 17 to 21 of the estrous cycle starting around Week 9 of lactation and determined on a subsample of cows (n =for FLA and n =5 for both MEG and SOY) were higher for cows fed FLA than for those fed SOY (P =0.04) or MEG (P =0.06). Conception rates were similar among treatments. Total embryo mortality was lower (P =0.07) for cows fed FLA (0%) compared to those fed either MEG (15.4%) or SOY (8.0%). The mean size of the CL measured during a complete estrous cycle from Week 9 of lactation was smaller for cows fed SOY (16.3mm) compared to those fed either FLA (19.1mm) or MEG (18.3mm). We inferred that pregnancy losses could be reduced by feeding whole flaxseed as a result of its effects on different factors such as modulation in concentration of progesterone and size of the CL. [Copyright &y& Elsevier]

Abstract: The objective of this study was to identify factors affecting variation in conception rate to first artificial inseminations (AI) (CR: number of pregnant cows on D80–100/inseminated cows) and the incidence of embryonic/foetal loss (LEM) between 21 and 80 days of pregnancy (number of cows non-pregnant on D80–100/pregnant on D21) in 44 low fertility dairy herds of the west-central region of France. Reproductive status was assessed using progesterone milk concentration on D0=Day of AI and D21–24, plasma PSPB concentration on D30–35, rectal palpation on D80–100 and observed return to oestrous. The final data set contained 1285 Prim’Holstein cows, 5.0% (64/1285) were inseminated in the luteal phase (progesterone ≥3ng/ml on D0), 61.3% (787/1285) were pregnant on D21–24 (progesterone<3ng/ml on D0 and ≥5ng/ml on D21–24), 15.4% lost their embryo/foetus between D21–24 and D80–100 (198/1285) and 45.8% (589/1285) were pregnant on D80–100. The incidence of late embryonic/foetal loss (LEM) was 25.2% (198/787). Multivariate logistic regression models including the random herd effect were used to analyse the relationship between AI centre, AI sire, cow''s sire, parity, interval between calving and AI, milk production, milk protein content, body condition score (BCS) on D0, season of calving, season of AI, estimated genetic index on CR and LEM incidence. CR was significantly related to parity (p <0.05), milk production after calving (p <0.05) and estimated genetic value (p <0.01). A significant difference in CR was observed for calving to AI interval ≤70 days versus ≥90 days, but the overall effect of the interval was not significant (p =0.11). LEM incidence was affected by period of AI (p <0.05), milk production (p <0.05) and BCS (p <0.05), but was not related to estimated genetic index. In conclusion, in these low fertility herds, the incidence of LEM was high and 25% of the cows lost their embryo after 21 days of pregnancy. LEM was affected by specific factors (season, BCS), which were not related to CR. The absence of a relationship between estimated genetic index and LEM in spite of its effect on CR indicates that estimated genetic merit has a greater effect on early embryonic loss or fertilisation failure than on later stages of embryo development. [Copyright &y& Elsevier]

Objective: To determine whether embryo quality is associated with early spontaneous loss rates in twin and singleton pregnancies after IVF/intracytoplasmic sperm injection (ICSI). Design: Retrospective, single center analysis. Setting: The Center of Reproductive Medicine, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. Patient(s): Women undergoing IVF/ICSI and two- or three-embryo transfer of intermediate- and top-quality embryos. Intervention(s): First-trimester sonography at 6 to 7 weeks to determine number of embryos with positive heartbeat. Number of embryos lost was calculated from a second-trimester sonogram. Main Outcome Measure(s): Rates of total pregnancy loss, as related to embryo quality, initial number of embryos, maternal age <35 or ≥35 years, and IVF procedure. Results: A total of 94 losses (23.1% of 407 pregnancies) were counted, with similar proportions in pregnancies after transfer of intermediate- or top-quality embryos. Neither the mode of IVF procedure nor the number of transferred embryos affected the loss rate. In contrast, the loss rate was significantly higher in older mothers after transfer of intermediate-quality embryos (odds ratio [OR 2.4], 95% confidence interval [CI] 1.1–5.5). Losses among singletons were significantly higher compared with losses among twins (OR 2.5, 95% CI 1.1–6.0), but this was observed in top-quality embryos only. Conclusion(s): Top-quality but not intermediate-quality ETs are associated with lower early spontaneous loss rates among twin pregnancies after IVF/ICSI. [Copyright &y& Elsevier]

During depopulation of a breeding unit within Swine Graphics Enterprises, extensive data were collected and used to examine relationships among ovulation rate, the pattern of prenatal loss, and placental and fetal development. Groups of Large White × Landrace females (n = 447) were slaughtered between day 20–30, 50–55 or 85–90 of gestation, with approximately equal numbers of animals representing gilts and parity 1 (G/P1), parity 2–3 (P2/3), and parity >4 (P4+). Ovulation rate and embryo number were recorded for all animals. With the exception of the G/P1 animals, embryonic and placental weight were recorded for four conceptuses per sow on day 20–30; on day 85–90 two conceptuses per sow were dissected to determine placental and fetal development. Ovulation rate (22.7 ± 0.2 overall) was higher (P < 0.05) in P2/3 (23.6 ± 0.4) and P4+ (24.7 ± 0.4) than in G/P1 (20.2 ± 0.5). Embryonic/fetal survival was 61.8 ± 2.1% at day 20–30, 50.2 ± 2.2% at day 50–55 and 48.7 ± 1.9% at day 85–90 and the number of surviving conceptuses was higher (P < 0.05) in the P2/3 sows than in other parity groups. There was no relationship between ovulation rate and number of live embryos at day 20–30 or 85–90. At day 20–30 and 85–90, embryo weight was positively correlated with placental weight, but neither placental weight nor embryonic/fetal weight was correlated with number of viable embryos. A parity by gestation day interaction existed; placental weight for P4+ (3.42 ± 0.43 g) was less than for P2/3 (7.55 ± 0.40 g) at day 20–30 (P < 0.0001), whereas at day 85–90, placental weight of P2/3 (209.5 ± 8.5 g) was less (P = 0.05) than both G/P1 (235.7 ± 7.3 g) and P4+ (235.4 ± 7.1 g). At day 85–90, fetal brain weight, relative to body weight (R2 = 0.61, P < 0.0001), and fetal brain:liver weight ratio (R2 = 0.35; P < 0.0001) were negatively related to mean fetal weight, and brain:liver weight ratio showed a trend towards a relationship with number of viable fetuses (P = 0.08). Parity also affected brain:liver weight ratio (P = 0.01). Clearly, high ovulation rates in the higher parity sows have the potential to cause excessive in utero crowding of conceptuses in the post-implantation period. Even with moderate crowding, increased brain:liver weight ratios in smaller fetuses in late gestation indicate that uterine capacity impacts fetal development as well as the number of surviving fetuses. [Copyright &y& Elsevier]

To investigate the influence of dibutyl phtalate (DBP) given in a soy-free rat chow on pre-pubertal development, 46 Long Evans female rats 2-month-old were divided into three experimental groups and fed three different chows: (1) control; (2) DP 0.61g/kg chow (12mg/kgrat/day); (3) DP 2.5g/kg chow (50mg/kgrat/day) for 2 months. While under this treatment, they were mated and their offspring studied. Litter size and female:male ratio were recorded. At 14 days of age 6, male pups of each group were sacrificed and testis and thymus were excised and weighed. Pups were weaned at 22 days of age and continued into three experimental groups according to diet. From day 22 onwards, vaginal opening, occurrence of first estrous, and pre-putial separation were recorded. Results: The percent of pregnancies showed a marked decrease in group 3, while no difference was observed between groups 1 and 2. Sex prevalence and litter size were not affected by the different diets. Pup survival showed a decrease when mothers were fed diet 2, but it was similar in diets 1 and 3. Pup weights on day 2 showed an evident (P < 0.05) reduction in groups 2 and 3, the decrease being more marked (P < 0.001) in group 3. On day 6, pups of group 2 showed lower weights (P < 0.01) as compared with the other groups. Weight gain was significantly higher in pups of group 3. Eye opening was not affected by the different diets. Fourteen-day-old male pups’ relative weight of thymus and testis showed a decrease in animals whose mothers had been fed diets 2 and 3. Vaginal opening and occurrence of first estrous showed an evident delay (P < 0.05; P < 0.01) in females fed diets 2 and 3. Significant differences (P < 0.001) in pre-putial separation were observed between treated and untreated groups. Conclusion: Offspring pre-pubertal development seems to be affected by oral intake of DBP by their mothers during pregnancy, the effects being more evident in the reproductive development of male pups. [Copyright &y& Elsevier]

Objective: To determine whether pregnancies after IVF, with and without intracytoplasmic sperm injection (ICSI), have different early spontaneous loss rates. Design: Retrospective analysis of IVF/ICSI dataset. Setting: The Center of Reproductive Medicine, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. Patient(s): Women undergoing IVF with or without ICSI. Intervention(s): First-trimester sonography at 6-7 weeks to count the number of embryos with positive heartbeat. The number of embryos lost was calculated from a second-trimester sonogram. Main Outcome Measure(s): Embryonic loss rates related to the initial number of embryos, maternal age <35 or > or =35 years, and IVF procedure. Result(s): In vitro fertilization and ICSI had similar embryonic loss rates (odds ratio [OR] 1.2, 95% confidence interval [CI] 0.9-1.7, and OR 1.3, 95% CI 0.9-1.8 for women aged <35 years and > or =35 years, respectively). Younger women had fewer losses after IVF (OR 0.7, 95% CI 0.5-0.9). Multiples had lower loss rates compared with singleton pregnancies. Conclusion(s): In vitro fertilization and ICSI have similar spontaneous embryonic loss rates. Factors other than the initial number of embryos, maternal age, and IVF technique, such as embryo quality or uterine environment, might be involved in the outcome of multiple pregnancies in assisted reproductive technology procedures. [ABSTRACT FROM AUTHOR]

One or two in vitro-produced (IVP) Japanese Black (JB) cattle embryos at 8 days after in vitro fertilization were transferred to the contralateral uterine horn of previously bred Japanese Shorthorn (JSH) or JSH–JB cross recipients, and then the occurrence of early embryonic death, abortion during mid- and late gestation, and calving loss were recorded. The survival rate of embryos, including indigenous ones, was not affected by the number of embryos transferred, and a significantly higher twinning rate (68% of pregnant recipients at 80 days after transfer) was achieved when two IVP embryos were transferred, as compared with the rate when one IVP embryo was transferred (24%). In late ET (recipients at 8.5–9.0 days after the onset of oestrus), the embryo survival rate (22%) and the pregnancy rate (42%) at 80 days after ET were significantly lower than those rates in the synchronous ET (recipients at 8.0 days after the onset of oestrus; 47 and 79%, respectively). In the early ET (recipients at 6.0–7.5 days after the onset of oestrus), no significant differences from the synchronous ET were detected in these rates. Twenty-six percent of twin pregnant recipients were aborted during mid- or late-pregnancy, and 39% of twin calves were stillborn. The mean gestation length of the twin-bearing JSH dams (276 days) was 1 week shorter than that of the single-bearing JSH dams, and it was 2 weeks shorter than that of the JB dams bearing a single JB calf derived from the IVP embryos. The longer gestation length of single JB calves derived from IVP embryos resulted in a significantly higher mean birth weight than that of in vivo control calves with the standard length of gestation.In conclusion, the number of embryos to be transferred did not affect the embryo survival rate, and the transfer of two IVP embryos to previously inseminated recipients induced a significantly higher twinning rate during early pregnancy than that of one IVP embryo transfer. The incidence of embryonic losses during early pregnancy increased when Day 8 embryos were transferred to the recipients later in the oestrous cycle (>8.0 days). The results suggested that one cause of the high rate of abortions and stillbirths in twin-bearing dams is the difference in the mean gestation length between the native JSH and JB foetuses derived from transferred IVP embryos. [Copyright &y& Elsevier]

Intensive genetic selection for increased milk production, coupled with increased dry matter intakes has led to significant improvements in cow milk yield, however, this increase in milk output has been accompanied by a decline in cow fertility. It has been suggested that there is a higher increment of late embryonic loss in high-yielding than in moderate yielding cows or in heifers. The objectives of this study were to establish the extent and pattern of embryonic loss, from days 28 to 84 of gestation, and to examine possible relationships between cow milk yield, cow genetic merit, parity, calving to insemination interval and embryonic loss in dairy cows managed mainly under pasture-based milk production systems. Multiparous dairy cows (n=1046) located on 8 farms and nulliparous dairy heifers (n=162) located on five of these farms were used in this study. The extent and timing of embryonic loss was measured by ultrasound scanning of the cows and heifers at 14-day intervals between days 28 and 84 of gestation. Positive diagnosis of pregnancy was based on the presence of an embryo or foetus with a visible heartbeat and, at the later scans, visible movement, whose size was compatible with stage of gestation and also on the presence of clear amniotic fluid of the cows and heifers presented as presumed pregnant on day 28 after insemination, 67 and 81%, respectively had a viable embryo. The subsequent embryonic loss rate between days 28 and 84 of gestation was similar (P>0.05) for cows (7.2%) and heifers (6.1%) and the pattern of loss over this period was also similar (P>0.05) for cows and heifers. There was no significant association (P>0.05) between level of milk production or milk energy output measured to day 120 of lactation and embryonic loss rate. Similarly, there was no significant relationship (P>0.05) between % milk fat, % milk protein and % milk lactose and embryonic loss rate. The extent and pattern of embryonic loss were not related (P>0.05) to either cow or to cow sire genetic merit. There was no significant (P>0.05) relationship between the calving to first service interval and embryonic loss. The extent of embryonic loss was greater (P<0.05) in cows that lost body condition between days 28 and 56 of gestation compared with cows than either maintained or improved in body condition. [Copyright &y& Elsevier]

Humans have low natural fecundity, as the probability of establishing a viable conception in any one menstrual cycle is 20–25% for a healthy, fertile couple. There are numerous underlying causes for this low rate of human fertility, not the least of which are intrinsic abnormalities within the oocyte and/or embryo, which likely account for greater than 50% of failed conceptions. During assisted reproduction technology (ART) interventions, controlled ovarian stimulation is used to obtain several oocytes in attempts to increase the likelihood of having at least one developmentally competent embryo available for transfer. However, current techniques for identifying the competent embryo(s) are by no means perfect. These limitations, coupled with pressures to maximize the chance of pregnancy, typically result in the transfer of multiple embryos. Not surprisingly, this practice has resulted in an unacceptably high rate of multiple pregnancies arising from ART. During the last few years, concerted efforts have focused on reducing these rates. Programs for ART are developing patient-specific policies, restricting the number of embryos to transfer. In addition, strategies are being adopted to improve the accuracy for selecting viable embryos for transfer. One such strategy involves further refinement of morphological criteria associated with improved viability by considering, for example, pronuclei disposition, nucleolar organization, and identification of the fast-cleaving embryos with only mononucleate blastomeres. Another strategy employs pre-implantation genetic diagnosis (PGD) whereby a biopsied blastomere is tested for ploidy using fluorescence in situ hybridization (FISH). A final strategy involves extending the duration of culture to the blastocyst stage, thereby allowing self-selection of those embryos capable of proceeding to blastulation and exclusion of those less viable embryos that succumb to developmental arrest. Together, these strategies are enabling fewer embryos of higher quality to be transferred. Accordingly, the overall pregnancy rate from ART continues to increase, while the rate of triplet and higher order multiple births continues to decline. Nevertheless, the high incidence of intrinsic developmental anomalies in human oocytes inevitably will continue to result in a high degree of embryonic loss in ART. [Copyright &y& Elsevier]

The reproductive performance of goats that received a GnRH analog (gonadorelin) fabricated with or without chitosan-sodium tripolyphosphate (TPP) nanoparticles on the day of estrus (day 0) was evaluated. The chitosan-TPP polymer was conjugated with gonadorelin using an ionic gelation method. Thirty-three multiparous Zaraiebi goats were synchronized for estrus with 2 intramuscular (im) injections of 125 μg prostaglandin F 2α 14 d apart. Goats showing signs of estrus were divided equally into 3 experimental groups and received a single im injection of 1 mL physiological saline (placebo; control), 50 μg/mL gonadorelin (GnRH), or 12.5 μg (quarter of GnRH dose)/mL chitosan-TPP–conjugated gonadorelin nanoparticles (NGnRH). Each goat underwent ultrasound imaging of their ovaries at day 0 and at day 10 after mating, and pregnancy was diagnosed 28 and 45 d after mating. The concentrations of estradiol (E 2) and progesterone (P 4) were determined at day 0 and at days 7, 14, 21, and 42 after mating. NGnRH size, polydispersity, and zeta potential were 93.91 nm, 0.302, and 11.6 mV, respectively. Chitosan-TPP nanoparticles showed 91.2% entrapment efficiency for GnRH. No differences in estrus rate, interval to estrus, or ovarian structure at day 0 were observed among the experimental groups, but the GnRH and NGnRH treatments significantly decreased the duration of estrus compared with the control. At day 10 after mating, both GnRH and NGnRH increased (P = 0.011) the number of corpora lutea compared with the control. Treatment with GnRH increased (P = 0.023) serum E 2 concentrations from day 7 to 42 after mating compared with NGnRH and control treatments. The highest (P = 0.043) serum P 4 concentration was observed in the GnRH group, followed by the NGnRH and control groups. The increase in serum P 4 concentration started earlier a on day 7 in the GnRH group but later on day 14 in the NGnRH group. Compared with the control, GnRH resulted in a higher (P = 0.041) P 4 -to-E 2 ratio, followed by NGnRH. Both gonadorelin treatments significantly increased the twinning rate, the number of embryos at days 28 and 42, and prolificacy and decreased pregnancy losses compared with the control. In conclusion, the administration of GnRH at the time of estrus improved the prolificacy of goats by increasing both the ovulation rate and the number of embryos. In addition, the nanoformulation developed in this study allowed a 75% reduction in the conventional dose of gonadorelin without affecting the fertility and prolificacy of goats, indicating the bioavailability of the reduced GnRH dose after conjugation with developed nanoformula. • Gonadorelin conjugated with chitosan- sodium tripolyphosphate nanoparticles (NGnRH) was developed to compare its biological activity with bare GnRH. • Reproductive performance of goats receiving either GnRH (50 μg) or NGnRH (12.5 μg) at the day of estrus was compared. • Both GnRH and NGnRH treatments increased serum P 4 concentrations, ovulation rates, and prolificacies. • The nanoformulation of GnRH was efficient to reduce the dosage of gonadorelin by 75%. [ABSTRACT FROM AUTHOR]