Animal Reproduction最新文献

The aim of this study was to evaluate the probability of pregnancy in heifers weaned at different ages and bred at 13 to 15 months old. A total of 121 Braford heifers were used, weaned as calves at 77 days (early) or 147 days (conventional) of age. To develop the statistical models of reproductive performance, factors related to the development of the heifers were analyzed. The analysis included a diagnosis of multicollinearity using the Pearson correlation matrix, adjusting the model by means of the Hosmer and Lemeshow test. The response variable, rate of pregnancy, was analysed using the LOGISTIC procedure. Beginning with a weight of 271 kg and an age of 402 days at the start of the breeding season, the pregnancy rates increased by 18.4% and 29.0%, respectively for every 15 kg increase in body weight and 10-day increase in age. However, a reduction of 15 kg in body weight and of 10 days in age reduced the pregnancy rates in the heifers by 15.5% and 22.5%. An increase or reduction of 0.100 kg in the average daily gain between early weaning and conventional weaning represented an increase of 44.6% and a reduction of 30.9% in the chances of pregnancy. Early-weaned heifers require correct nutritional management to allow satisfactory postweaning weight gains so as not to compromise their reproductive performance.

Luteinizing hormone (LH) plays a crucial role in follicle development, ovulation induction, and the regulation of key reproductive events. However, the efficacy of LH within the follicular microenvironment largely depends on the capacity of follicular cells to express its receptor. This study aims to investigate whether granulosa cells (GCs) can acquire LHR through extracellular vesicles (sEVs) present in follicular fluid (FF) from follicles of varying sizes. In the first experiment, GCs and sEVs were collected from the FF of small (3-5 mm), medium (5.1-7 mm), and large (7.1-9 mm) ovarian follicles from Bos taurus indicus cows. In the second experiment, GCs and sEVs were collected from the FF of small (3-6 mm) and large (8-14 mm) follicles from Bos taurus taurus cows. Initially, we assessed the ability of sEVs to carry LHR mRNA by comparing its expression profiles in sEVs derived from different size follicles. Our findings revealed that as follicular development progresses, LHR levels in FF sEVs decrease, while in corresponding GCs, from which the sEVs primarily originate, show increased LHR expression. To further investigate whether GCs represent an additional source of FF sEVs carrying LHR mRNA, GC cultures were established and sEVs secreted into the culture medium (ME-sEVs) were analyzed for LHR mRNA levels. A similar pattern was observed in ME-sEVs derived from GCs of small versus large follicles, with decreased LHR mRNA levels in sEVs secreted by GCs from large follicles compared to small follicles. This suggests that LHR is likely packaged into sEVs in small follicles stage, and shuttled into follicular cells during follicular growth, preparing them for the ovulatory stimulus. Our study uncovers a possible mechanism of LHR acquisition by GCs, which involves EVs and can possibly be involved in follicle quality and ability to respond to LH stimulus.

The aim of this study was to evaluate the effects of in vivo oocyte maturation using seminal plasma alone or in combination with an additional period of in vitro maturation (IVM) on the developmental competence of alpaca oocytes. The experiment was conducted in Lima, Peru, with twelve adult female alpacas. Follicular ablation of the dominant follicle was performed to initiate a new follicular wave. After 36 hours, a superstimulation protocol with 750 IU of eCG was administered intramuscularly (IM). Four days later, 2 mL of seminal plasma was administered IM to promote in vivo oocyte maturation. Cumulus-oocyte complexes (COCs) were retrieved via ovum pick-up 20 hours post-treatment, morphologically evaluated, and allocated into three groups: (T1) no additional IVM, (T2) 12 hours of additional IVM, and (T3) 18 hours of additional IVM. Oocyte developmental competence was assessed using a 26 µM brilliant cresyl blue (BCB) staining protocol for 90 minutes. COCs were classified as BCB positive (blue ooplasm) or BCB negative (unstained ooplasm) and subsequently denuded and fixed for nuclear maturation assessment via orcein staining. No significant differences (p=0.14) were observed in the percentage of expanded COCs across groups (71.4%, 81.8%, and 54.6% for T1, T2, and T3, respectively). The proportion of COCs reaching the metaphase II (MII) stage was higher (p<0.05) in T3 (54.6%), while the developmental competence rate was greatest (p<0.05) in T2 (100%). However, no differences (p=0.21) were detected in the proportion of BCB positive MII stage COCs across groups. In conclusion, alpaca oocytes matured in vivo with seminal plasma require 12 to 18 hours of IVM to achieve optimal nuclear maturation and developmental competence.

Serum calcium fluctuations are common during the peripartum period of dairy cattle and several studies have attempted to demonstrate the impact of decreased blood calcium (Ca) on subclinical endometritis; however, the highly dynamic and complex nature of the peripartum period in dairy cows may impair the establishment of the cause-and-effect relationship. The objective of this review is to compile information regarding hypocalcemia and subclinical endometritis and their relationship, as well as the available in vivo and in vitro study models that artificially induce subclinical states of hypocalcemia and endometritis in cows that are not in peripartum period. Regarding hypocalcemia, several studies have demonstrated the effectiveness and safety of protocols using Ca chelators such as ethylenediaminetetraacetic acid (EDTA) or ethylene glycol tetraacetic acid (EGTA) in vivo. The induced transitory hypocalcemia impaired feed intake, rumination and neutrophilic phagocytic and oxidative burst response. However, the effects on uterine environment remain poorly explored. Although these experimental models allow the understanding of the effects of hypocalcemia alone, without the peripartum metabolic and hormonal variations, the effects are likely underestimated because dairy cows may experience hypocalcemia for much longer periods. For studying bovine endometritis, the main experimental in vivo model is the intrauterine infusion of pathogenic bacteria or their components (lipopolysaccharide - LPS), which induce endometrial inflammation, even causing long-term negative effects. Several in vitro and ex vivo models have also been developed, which are mainly indicated to investigate the mechanisms underlying endometrial inflammation in cattle because there is no interaction with other tissues, organs and systems, as would occur in vivo. In conclusion, current models still face limitations and, therefore, future efforts to the development and refinement of in vivo and in vitro experimental models are necessary.

The aim of this study was to evaluate the effects of supplementing the cryodiluent medium with sulfated polysaccharides (SP) extracted from marine algae (Ascophyllum nodosum or Solieria filiformis) and fish skin (Colossoma macropomum, Prochilodus brevis, or Oreochromis niloticus) on the cryopreservation of tambaqui semen. Twenty male tambaqui were used for semen collection and cryopreservation. For the fertilization assay, three males and five females were used. In Experiment 1, different concentrations of SP (0.0, 0.1, 0.25, 0.5, and 0.75 mg/mL) extracted from fish skin or marine algae were added to the freezing medium for C. macropomum semen. In Experiment 2, the results of sperm velocity analyses were used to select one concentration of each sulfated polysaccharide for use in fertilization trials. Among the treatments, A. nodosum at 0.75 mg/mL and C. macropomum at 0.50 mg/mL stood out, significantly improving sperm parameters such as motility, VCL, VSL, VAP, and LIN compared to the control group. S. filiformis, P. brevis, and O. niloticus also showed good results, with performance varying by concentration. Membrane integrity was higher in the algae-derived extract groups. Sperm morphology and DNA integrity did not differ significantly among groups. Fertilization rates remained high across all treatments (84.67% to 88.67%), with no statistically significant differences, indicating that the tested extracts did not compromise fertility. It was concluded that supplementation with SP from A. nodosum at 0.75 mg/mL and C. macropomum at 0.50 mg/mL, although all treatments showed similar fertility rates, is recommended as an additive to the semen dilution medium for tambaqui during freezing, as it improved important sperm parameters such as motility and VCL.

The genes identification involved in male reproduction and the evaluation of its functions improve the comprehension about spermatogenesis molecular bases, fertilization, embryos early cleavage, spermatic quality and male infertility. The present study aimed to verify the Protamine1 (PRM1), Protamine2 (PRM2) and Cation Channel Sperm Associated 1 (Catsper1) genes expression into the equine sperm and their relations with the stallions' spermatic quality and fertility. Semen collections were performed in eighteen stallions, which were divided in two groups, based on fertility rates: fertile (with pregnancy rate per cycle ≥ 70%) and subfertile (with pregnancy rate per cycle ≤ 40%). The semen analysis was performed by Computer Assisted Sperm Analysis AndroVision®. The mRNA was extracted from the spermatozoa and the PRM1, PRM2 and Catsper1 gene expression verification in the spermatic cell was conducted by the qPCR technique. The results present a higher expression of PRM1 and Catsper1 in the fertile stallions' group than subfertile group; there was no correlation of PRM1 and PRM2 expression with spermatic quality parameters; there was correlation of the Catsper1 expression with morphology and motility parameters. Negative correlation was found between the PRM1/PRM2 ratio, fertility and motility parameters. The present research demonstrates that the PRM1 and Catsper1 genes are related to stallions' fertility and spermatic quality, and they may work as biomarkers.

The aim of this study was to evaluate the effect of follicular wave synchronization and equine chorionic gonadotropin (eCG) prior to ovum pick-up (OPU) in Braford cows on the oocyte competence, maturation rate, and in vitro embryo production. Cows (n = 27) were divided into three groups on a crossover model: no treatment prior to OPU (Control), follicular wave synchronization (Synchro), and synchronization plus 800IU of eCG (eCG800). Donors of the groups Synchro and eCG800 were synchronized with 2 mg of estradiol benzoate (EB), prostaglandin F2α analogue (PGF2α) and intravaginal device with 1g of progesterone (P4) on D0. On day 3, eCG800 group donors received 800IU of eCG. On day 6, OPU was performed, and the number of follicles were counted and classified by diameter in small, medium, and large. In experiment 1, the viable oocytes were evaluated for competence development, nuclear maturation, and mitochondrial reorganization. In experiment 2, oocytes were matured, fertilized, and cultured in vitro to blastocyst stage. All analysis was performed by ANOVA, and the differences were compared by Tukey's test with significance P ≤ 0.05. The use of 800 IU of eCG increased (P < 0.05) the number of medium and large follicles compared to the Syncro group. The oocyte recovery, viability, nuclear or cytoplasmic maturation, cleavage, and grade 1 embryos rate did not differ among groups (P > 0.05). The blastocyst rate on D7 showed tendency (P = 0.075) to improve from Control (17±6.08%) to Synchro (23.8±8.95%) to eCG800 (37.3±6.51%). The dose of 800 IU of eCG 72 h before OPU increased the proportion and number of medium and large follicles in relation to the Control and Synchro groups, without affecting oocyte competence and tending to produce more blastocysts on D7.

We tested the effects of centrifuging in vitro matured bovine oocytes for varying times on embryo development and cryotolerance. The oocytes were divided into four groups: control (GC) and centrifuged groups [5433 x g: G5, n = 463 (5 min); G10, n = 461 (10 min); and G15, n = 483 (15 min)]. After centrifugation, the oocytes underwent in vitro fertilization for embryo production. Two parameters were evaluated: i) embryonic development (n = 1,878), and ii) cryotolerance evaluation (survival and hatching rates; n = 303). The CG and G10 groups showed blastocyst rates of 42.25% and 45.77%, respectively, higher than those of the other groups (p = 0.02). The hatching rate was equal (p > 0.05) in CG (91.96%), G5: (87.74%), and G10: (95.73%) groups; however, it was lower in G15: 77.06% (p < 0.01). In the CG group, 65.88% of cryopreserved embryos survived, which was different (p < 0.05) from that in G5 (82.02%) and G10 (82.28%) (p > 0.05). Post-freeze hatching percentage was 74.0%, 87.7%, and 47.7%, in G5, G10, and G15, respectively, which was significantly greater than that in CG (p < 0.01; 26.8%). Post-freeze hatching percentage in only G10 matched that of the non-cryopreserved embryos CG (p = 0.06, 92%). We conclude that oocyte centrifugation for 10 minutes was efficient for in vitro embryonic development and cryopreservation of cattle embryos.

To establish a mouse embryo bank at the Institute of Science and Technology in Biomodels, Oswaldo Cruz Foundation (ICTB/FIOCRUZ), embryos from genetically modified strains were vitrified. The strains included B6.129SVEV-CCBP2 (D6), B6.129P2-Nos2 (Nos2), B6.129S2-Cd28 (Cd28), B6.129P2-Ccl3 (Ccl3), B6.129S2-Alox5 (Alox5), B6.129P2-Ccr2 (Ccr2), B6.129P2-Ccr5 (Ccr5) and B6.129S1-Tlr6 (Tlr6). To accomplish this, the animals were superovulated and mated, and their embryos were collected and vitrified. The success of the technique was evaluated by examining the development of the embryos through thawing and in vitro culture, comparing them to a control group. The results were analyzed using percentages, Tukey's t-test, and Analysis of Variance. The embryonic development percentages for the different strains were as follows: D6 (55%), Nos2 (24.7%), Cd28 (45.8%), Ccl3 (50%), Alox5 (4.8%), Ccr2 (66.7%), Ccr5 (63.04%) and Tlr6 (52.8%). Significant differences were observed between the strains Nos2 (p=0.0434), Cd28 (p=0.034), Ccl3 (p=0.0006), and Alox5 (p=0.0166) compared to their respective control groups. In conclusion, the strains Ccr2 (p= p=0.0889), Ccr5 (p=0.0806), D6(p=0,0685) and Tlr6 (p=0.0806) demonstrated favorable results in terms of the vitrification protocol and subsequent embryonic development, as they did not significantly differ from the control groups.

This study aimed to characterize the ovarian follicular dynamics in locally adapted Curraleiro Pé-Duro cows and heifers. Cyclic heifers (n =12) and non-lactating, multiparous cows (n = 11) were examined daily by ultrasonography for two consecutive ovulations (an estrous cycle). Follicles > 3 mm and corpus luteum (CL) were measured and followed until they disappeared. Follicular and luteal characteristics were not different between heifers and cows. Consequently, data on cows and heifers were combined according to the number of follicular waves. Follicular dynamics was characterized by the predominance of two (36.8%) and three (63.2%) follicular waves. No difference in estrous cycle length between these follicular wave patterns was observed. The number of recruited follicles was smaller in the second follicular wave. The ovulatory follicle (OF) growth rate (mm/d) and maximum diameter were greater (P < 0.05) in females, showing three waves. The ovulatory wave was shorter (P < 0.05) than the preceding waves regardless of the wave pattern. No difference was found in CL development between females with two and three follicular wave patterns. Some follicular dynamics characteristics were similar to Bos taurus and others similar to Bos indicus, confirming the crosses made throughout the years. The data from this study will be useful to better estrous cycle manipulation aiming for good results in artificial insemination (AI), fixed-time AI (FTAI), and multiple ovulation and embryo transfer (MOET) programs.