Animal Reproduction最新文献

Repeat breeder (RB) syndrome plays a detrimental role on fertility and economic performance of dairy farms. Regarding its multifactorial origin, it has been stated that an immunological response in the female genital tract may impair sperm viability. Therefore, the aim of this study was to evaluate the concentration of immunoglobulins in cervical mucus of RB cows and its influence on sperm motility. Fifteen fertile cows and 32 RB cows were included in the study. Cervical mucus samples were collected at the time of artificial insemination (AI). The concentration of IgG and IgA was determined by radial immunodiffusion. Sperm motility in cervical mucus was evaluated by CASA system. Our results showed no significant differences between cows with or without RB syndrome regarding the concentration of immunoglobulins in cervical mucus and sperm motility. The only factor affecting sperm motility was time. Consequently, it may be probable that a local immune response against spermatozoa is not one common cause of RB syndrome.

Successful implementation of conservation programs for endangered species requires biological material for use in reproductive biotechnologies. This enhances reproductive efficiency and helps increase the populations of critically endangered species. One way to facilitate the exchange of genetics between captive and free-ranging animals is through the creation of cryogenic banks that store cryopreserved gametes. In particular, semen cryopreservation allows for this exchange to occur. We evaluated whether the use of exogenous hormones (such as oxytocin and prostaglandin) prior to electroejaculation increases seminal volume, sperm concentration, and the number of doses produced in the red brocket deer (Mazama rufa). We also evaluate whether seminal parameters vary over the three stimulation cycles of the same electroejaculation procedure. The treatments did not affect ejaculate volume (p = 0.402), the number of sperm cells in the ejaculates (p = 0.926), total doses produced (p = 0.684), sperm mass movement (p = 0.229), sperm cell concentration (p = 0.106), and acrosome integrity (p = 0.210). The use of hormones has potential in reducing the need for stressful stimuli in electroejaculation, but the choice of hormones must take into account their effects on semen quality.

Small ruminant farming plays a pivotal role in agriculture, especially in developing countries due to sheep's diverse functions and capacity to acclimate to varying temperatures. This review comprehensively explored the impact of rising temperatures on reproductive processes, reproductive function encoding gene expression, and sheep's ability to adapt to heat stress. Several mechanisms contribute to sheep's resilience to heat stress, encompassing morphological, behavioral, physiological, and genetic adaptations. It has been shown that heat stress compromises fertility by affecting follicular development, ovulation rate, estrous behavior, rates of conception, embryonic survival, and fetal development, while also disrupting sperm production and motility, and increasing the incidence of structurally abnormal sperm in males. Estimates suggested that heat stress may reduce conception rates from 20% to 27%. Essential genes encoding the Gonadotrophin-releasing hormone, Follicle-stimulating hormone receptor, Luteinizing hormone receptor, Estradiol receptor, progesterone receptor, and Inhibin play a critical role in elucidating how heat stress impacts the reproductive performance of sheep. Furthermore, the resilience of sheep in facing heat stress adversities is associated with a specific heat shock factor. When an animal is under heat stress, Heat shock factors get activated and stimulate the production of Heat Shock Proteins (HSPs). Emphasis should be given to identifying specific genes and candidate genes that confer protection against heat stress and conducting comprehensive research to unravel how sheep adapt to demanding local climatic conditions to enhance production and profitability, improve animal welfare, and for genetic conservation and breeding programs.

Porcine breeding industries typically ensure the viability of boar artificial insemination doses during a 5-day liquid storage period at 17 °C. This study aimed to investigate whether the addition of L-carnitine (LC) to boar semen doses on different days of cooled storage could extend their usability. In experiment 1, LC was added to porcine semen doses on the fifth day (d5) of cooled storage performing five treatments control (no LC), 0.5, 1-, 5- and 10-mM LC. On d6 and d8 of storage, semen samples were evaluated for sperm motility and kinematic parameters, membrane functionality, and hydrogen peroxide and nitrite concentrations. In experiment 2, the number of sperm bound to the zona pellucida (ZP) was determined, as a way to investigate sperm penetration capability from boar insemination doses, with co-incubation with porcine oocytes. LC concentration that produced the most favorable outcomes in Experiment 1 was chosen to experiments 2 and 3, performing two treatments in the absence and with the LC. In Experiment 3, LC was added to cooled porcine semen doses after one day of storage (d1), and the same evaluations of experiment 1 were conducted on days 5, 7, 9, and 12, including sperm membrane integrity. The addition of 10 mM LC on d5 and d1 of storage improved sperm motility, which was extended up to 8 and 12 days of cooled storage, respectively. LC addition on d5 of storage increased sperm membrane functionality, while when added to semen on d1 of storage, it decreased NO₂ ^- concentration on d9. On d6 of cooled storage 10 mM LC increased the number of sperm bound to ZP compared to the control. In conclusion, adding 10 mM LC to porcine semen doses at 17 °C improved sperm characteristics and ZP binding, ultimately enhancing sperm viability for up to 12d.

The objective of this study was to investigate the effects of GnRH at insemination on pregnancy and lambing in seven ewe populations during the breeding season. Estrus was synchronized in 1560 adult ewes using an intravaginal sponge impregnated with flurogestone acetate. The sponge was left in the vagina for 12 days followed by an injection of 330 IU of eCG at sponge removal. Each ewe was inseminated twice at 48 h and 60 h after sponge removal. The treatment group was intramuscularly injected at the first insemination with a dose of 16 μg GnRH and the control group with saline solution in each ewe population. The results showed that GnRH administration significantly decreased the pregnancy rate in three ewe populations, but had no effects in four ewe populations. Additionally, the litter size tended to increase in the treatment group compared to the control group in all seven ewe populations, but the difference was not significant. In conclusion, GnRH administration at insemination was not recommended for ewes undergoing a timed artificial insemination during the breeding season. The breed/population may be a critical determinant of the potential for exploiting GnRH application in sheep breeding programs.

Anti-Müllerian Hormone (AMH), a member of the TGF-β superfamily, plays a critical role in mammalian fertility. This study aimed to investigate AMH concentrations in pregnant buffalo cows and their fetuses, and to characterize the cellular distribution and immunolocalization of AMH within fetal gonads. Gonads were collected from 12 male and 14 female buffalo fetuses, fixed in 10% buffered formalin, and processed for routine histological analysis and immunohistochemical localization of AMH. Blood samples were collected from 26 pregnant buffalo cows and their corresponding fetuses into EDTA-coated tubes. AMH levels in both maternal and fetal blood were quantified using a commercially available bovine AMH ELISA kit. Significant (p < 0.05) inter-individual variations in maternal and fetal AMH concentrations were observed. In males, fetal AMH concentrations increased significantly with gestational age, with levels substantially higher compared to females at all gestational ages (52-1222 times higher). Immunohistochemistry revealed intense AMH immunoreactivity in the cytoplasm of pre-Sertoli cells in male fetuses. In females, no significant correlation was found between fetal AMH concentrations and follicular populations, although intense AMH immunostaining was observed in the cytoplasm of oocytes within primordial follicles. These findings suggest that fetal AMH concentrations in buffaloes are influenced by gestational age and sex, and that fetal AMH likely does not readily cross the placental barrier. Further investigations are warranted to elucidate the intricate role of AMH in gonadal development and function in buffaloes.

Owing to the low heritability of reproductive traits, the search for markers and their interrelationship that could indicate reproductively superior individuals is important in the selection process for bovine reproductive efficiency. This study aimed to investigate the possible interrelationships between the antral follicle count (AFC), vulvar-width (VW), anti-Müllerian hormone (AMH) concentrations, fertility in Bos Taurus and Bos Indicus females. Brahman (Bos Taurus-Indicus, n = 126) and Simmental and Angus (Bos Taurus-Taurus, n = 155) cows were classified as having large (≥86 mm) and small (<86 mm) VW. From each group, one blood sample per animal was collected to determine the AMH serum concentrations. The GLIMMIX procedure in SAS^® was used to determine whether vulva width (VW) and AMH classes, associated or not with breed, could influence the age at first calving (FCA), calving to first service interval (CFSI), calving interval (CI), number of services per pregnancy (SP), and number of viable oocytes (VO). Antral follicle count (AFC) (36.10 ± 1.90 vs. 22.78 ± 1.64, for large and small VW, respectively), AMH (1.17 ± 0.07 vs. 0.48 ± 0.007 ng/mL), and viable oocytes or VO (18.86 ± 1.76 vs. 10.15 ± 1.49) were greater (P < 0.05) in the large VW than in the small VW. Brahman cows had greater AFC (36.30 ± 1.34 vs. 22.09 ± 1.67), VW (106.94 ± 15.83 vs. 69.78 ± 14.11 mm), and AMH (1.18 ± 0.07 vs. 0.42 ± 0.05 ng/mL) compared to that of taurine cows. In conclusion, VW was an efficient predictor of AFC and AMH concentrations in both genetic groups, but under the conditions of this trial no link could be detected between these variables and the reproductive indices studied.

The aim of this study was to evaluate the influence of diluent, stored volume and the cryodiluent medium supplementation with sulfated polysaccharides (SP) extracted from Nile tilapia skin on P. brevis vitrified sperm. Six pools were diluted in 5% Glucose or Powder Coconut Water (ACP-104), supplemented or not with 0.5 mg/mL of SP, and submitted to vitrification. Subsequently, they were stored in cryotubes in two volumes (60 μL and 420 μL). After 15 days, the samples were devitrified and evaluated for kinetics, membrane integrity and sperm DNA integrity. ACP-104 proved to be the best diluent for P. brevis sperm vitrification. Membrane and DNA integrity rates were higher (P < 0.05) when stored in smaller and larger volume, respectively. Additionally, the best rates (P < 0.05) of these same parameters were obtained with supplemented medium. There was interaction (P < 0.05) between diluent and stored volume, with ACP-104 exceeding 5% Glucose for motility in both volumes, while for average path speed (VAP) and membrane integrity the same happened in the larger volume. 5% Glucose had higher VAP and membrane integrity when stored in smaller volume. There was a triple interaction (P < 0.05) for DNA integrity, and better results were obtained when semen was vitrified in ACP-104 and stored in the larger volume, regardless of supplementation, which influenced only the 5% Glucose medium in the smaller volume. It was concluded that ACP-104, supplemented with SP and stored in larger volume make up the best treatment for P. brevis sperm vitrification.

This study aimed to characterize the reproductive parameters and economic indicators of dairy farms. Data were from technical assistance of the Programa de Desenvolvimento em Pecuária Leiteira (PDPL-UFV) including 26 farms, from September 2022 to August 2023, comprising an entire production cycle. The following economic indicators were selected as dependent variables: Unit Net Margin (UNM), Operating Profitability (OP) and Rate of Return on Capital (RRC). Reproductive parameters were used as explanatory variables in multiple linear regression analysis. A stepwise selection was performed and only variables significant at p < 0.10 were kept in the final model. Pregnancy rate of cows, number of inseminations per pregnant heifer, and replacement rate were the reproductive parameters with the greatest effect on the evaluated economic indices. The UNM and OP were positively affected by pregnancy rate of cows and number of inseminations per pregnant heifer, but replacement rate negatively affected both indices. Only the pregnancy rate of cows showed a significant and positive effect on RRC. Results suggest that the economic viability of a dairy farm is not only associated with cutting costs such as reducing the number of inseminations in heifers, or increasing revenue by selling animals, which increases the replacement rate.

Somatic cell nuclear transfer (SCNT), or cloning, is used to reprogram cells and generate genetically identical embryos and animals. However, the cloning process is inefficient, limiting its application to producing valuable animals. In swine, cloning is mainly utilized to produce genetically modified animals. Indeed, recombinant DNA technologies have evolved considerably in recent years, with homologous recombination and gene editing technologies becoming more efficient and capable of recombining both alleles in a single cell. The selection of appropriate cells and their use as nuclear donors for SCNT is the most common method for generating edited and genetically modified animals for commercial and research purposes. This article reviews current applications of swine cloning and shares our personal experiences with the procedure in this species.