Animal Reproduction最新文献

{"title":"Let the female tract choose: finding the sperm to enhance <i>in vitro</i> embryo production.","authors":"Marie Saint-Dizier, Luna Ehrhardt, Alba Perez-Gomez, Joanna Maria Gonçalves Souza-Fabjan, Coline Mahé","doi":"10.1590/1984-3143-AR2026-0061","DOIUrl":"10.1590/1984-3143-AR2026-0061","url":null,"abstract":"<p><p><i>In vitro</i> embryo production (IVEP) has become an essential tool for livestock breeding, genetic dissemination, and research. Despite its widespread use, overall efficiency remains limited, as only approximately 25% of fertilized oocytes develop into transferable embryos, and pregnancy outcomes are consistently lower than with <i>in vivo</i>-derived embryos. While oocyte quality is a major determinant, fertilization success and early embryonic development are also strongly influenced by sperm functional competence, which is only partially captured by conventional selection methods based primarily on motility and morphology. <i>In vivo</i>, the female reproductive tract imposes stringent physical and molecular barriers, with fewer than 0.01% of inseminated sperm reaching the fertilization site. This selection involves key processes, including i) passage through the utero-tubal junction, ii) formation and regulation of the oviductal sperm reservoir, and iii) guided sperm navigation toward the oocyte. These mechanisms ensure functional selection of sperm and synchronized meeting with oocytes, features that are largely absent or poorly replicated in conventional <i>in vitro</i> fertilization (IVF) systems. Current sperm selection methods include swim-up and density gradient centrifugation. Emerging biomimetic approaches aim to better replicate physiological conditions, notably through microfluidic platforms and oviduct cell-based selection systems. These approaches have shown promising improvements in IVEP, although their routine application remains constrained by limited throughput, standardization, and scalability. This review synthesizes current knowledge on both the <i>in vivo</i> mechanisms of sperm selection and emerging biomimetic techniques, particularly in cattle, where improving sperm selection remains a key challenge for IVEP efficiency.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 4","pages":"e20260061"},"PeriodicalIF":2.3,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412149/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular and developmental consequences of heat stress on the bovine oocyte and embryo competence.","authors":"Ghyslaine Giselle Ramírez, Nico Graham Menjivar, Samuel Gebremedhn, Ahmed Gad, Eva Held-Hoelker, Michael Hoelker, Genet Zewdie, Dawit Tesfaye","doi":"10.1590/1984-3143-AR2026-0067","DOIUrl":"10.1590/1984-3143-AR2026-0067","url":null,"abstract":"<p><p>Seasonal heat stress (HS) is a pervasive environmental challenge with profound consequences for female reproductive physiology, affecting ovarian function, oocyte maturation, and early embryonic development. At the ovarian level, HS disrupts follicular growth, impairs steroidogenesis, and compromises granulosa cell function, thereby creating a suboptimal microenvironment that reduces oocyte competence. In oocytes, HS induces oxidative stress, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, spindle abnormalities, chromosomal missegregation, and persistent epigenetic alterations. These disruptions extend into early embryonic development, where redox imbalance, apoptosis, ER stress, and altered lineage allocation reduce cleavage and blastocyst formation, compromise trophectoderm and inner cell mass integrity, and impair implantation potential. Maternal heat exposure further exacerbates embryonic vulnerability by altering the oviductal and uterine environment, reducing embryotrophic factors and antioxidant defenses, and ultimately influencing offspring phenotype and fertility, potentially across generations. Accordingly, this review aims to synthesize current knowledge on the physiological and molecular impacts of heat stress on ovarian function, oocyte maturation, and early embryonic development. To this end, we consider studies conducted under both in vivo and in vitro conditions, highlighting shared and distinct mechanisms of thermal stress at the organ and cellular levels to identify potential targets for intervention.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 4","pages":"e20260067"},"PeriodicalIF":2.3,"publicationDate":"2026-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412142/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Histological features of <i>Jaculus jaculus</i> male-reproductive system: detection of metalloproteinases in testes and seminal vesicles during the active-reproductive phase.","authors":"Nesrine Zeghloul, Nemcha Lebaili-Benmoussa, Mohamed El Fadel Ousmaal, Salim Lamine, Nesrine Lina Gharnaout, Sabrina Lekmine, Nassim Moula, Walid Elfalleh, Fehmi Boufahja, Hamdi Bendif, Hichem Tahraoui, Abdeltif Amrane","doi":"10.1590/1984-3143-AR2025-0117","DOIUrl":"10.1590/1984-3143-AR2025-0117","url":null,"abstract":"<p><p>Our study explored the histological and histo-functional characteristics of the testis and seminal vesicles of <i>Jaculus jaculus</i>, collected from the Biskra (34° 51' 0\" N 5° 43' 59.999\" E) and M'sila regions in Algeria (35°42'20.99\" N 4°32'30.98\" E) from autumn to early spring, corresponding to activity and transitional periods of the reproductive cycle. An immunohistochemical analysis of matrix metalloproteinases (MMP-2 and MMP-9) was conducted on the seminal vesicles and testes during the active reproductive. The study utilized an indirect immunohistochemistry protocol with amplification through streptavidin-biotin-peroxidase. Histologically, seminiferous tubules in <i>Jaculus jaculus</i>, captured during the transitional period of the reproductive cycle, multinucleated giant cells of germinal origin were observed during the transitional phase of the reproductive cycle, reflecting a process of seasonal testicular remodelling. The histological structure of seminal vesicles appears highly characteristic of the studied species, with the vesicular epithelium organized into complex acinar glands surrounded by basal lamina and connective tissue. Gland cells secrete a heterogeneous product. In the testis, cells of the seminiferous epithelium express MMP-2 and MMP-9 in their cytoplasm, with a strong expression of MMP-2; however, both proteins are absent from the extracellular matrix. During the active period, in seminal vesicles, a significant immunohistochemical signal of MMP-2 and MMP-9 was observed in epithelial cells, smooth muscle cells, with no immunoexpression in the extracellular matrix. MMP-2 and MMP-9 are expressed in a pattern consistent with a potential role in the seasonal reproductive cycle.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250117"},"PeriodicalIF":2.3,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412014/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryopreservation of jaguar (<i>Panthera onca</i>) fibroblast-like cells in straws and cryovials: a comparison of rapid and slow-freezing protocols.","authors":"Sofia Regina Polizelle, Ian Figueiredo Navarezi, Maite Cardoso Coelho da Silva, Giulia Correia Vieira, Liandra Martiliano Gaeth, Larissa Schneider Brandão-Souza, Bianca Rodrigues Acacio, Pedro Nacib Jorge-Neto, Eliane Vianna da Costa E Silva, Thyara de Deco-Souza, Alexsandra Fernandes Pereira, Gediendson Ribeiro de Araujo","doi":"10.1590/1984-3143-AR2025-0096","DOIUrl":"10.1590/1984-3143-AR2025-0096","url":null,"abstract":"<p><p>Somatic cells serve as essential genetic resources for biobanking. Traditionally, jaguar fibroblast-like cells are frozen in cryovials using slow-freezing protocols. However, this approach necessitates access to ultra-low temperature freezers and requires substantial storage capacity. This study aimed to evaluate the efficacy of a rapid-freezing protocol as a feasible alternative for the freezing of jaguar fibroblasts. Following cultivation to the third passage, cells were frozen using either slow-freezing (SF) or rapid-freezing (RF). For SF, cells were frozen in cryovials (-1 ºC/min), whereas RF involved rapid-freezing (-60 ºC/min) using nitrogen vapor and storage in 0.25 mL straws. Post-thaw, cells were re-cultured to assess recovery. Cell viability was assessed via light microscopy (Trypan blue), fluorescence microscopy (acridine orange + propidium iodide), and flow cytometry (Hoechst 33342 + propidium iodide) immediately post-thaw and upon reaching confluency (> 80%). Fresh culture viability assessed by Trypan blue, acridine orange, and flow cytometry was 98.2 ± 0.3%, 88.7 ± 3.9%, and 94.2 ± 2.2%, respectively. No significant differences in viability were observed between SF and RF immediately post-thaw or after subsequent cultivation. All three assays revealed significant differences (<i>p</i> < 0.05) between cells assessed immediately after thawing and those assessed at confluence. Upon reaching confluence, there was no significant difference (<i>p</i> > 0.05) between fresh and frozen-thawed cells. These findings indicate that RF in straws is a viable alternative to SF for jaguar fibroblast cryopreservation, offering optimized storage density for genetic resource banks.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250096"},"PeriodicalIF":2.3,"publicationDate":"2026-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412005/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Slow freezing and 3D <i>in vitro</i> culture of prepubertal goat testes after short-term conservation.","authors":"Francisco Denilson Rodrigues Gomes, Lucy Vanessa Sulca Ñaupas, Gaby Judith Quispe Palomino, Rensson Homero Céliz Ygnácio, Naiza Arcângela Ribeiro de Sá, Anna Clara Accioly Ferreira, Marco Aurélio Schiavo Novaes, Gustavo Bezerra Nobre do Vale, Bruna Novaes Costa, Carolina Madeira Lucci, César Carneiro Linhares Fernandes, Davide Rondina, Alexandre Rodrigues Silva, José Ricardo de Figueiredo, Gildas Mbemya Tetaping, Ana Paula Ribeiro Rodrigues","doi":"10.1590/1984-3143-AR2025-0139","DOIUrl":"10.1590/1984-3143-AR2025-0139","url":null,"abstract":"<p><p>This study This study aimed to evaluate two conservation times (2h vs 6h) at 4 ºC of prepubertal goat testicles for subsequent slow freezing and 3D in vitro culture. Testicular fragments from six animals were preserved at 4 ºC for 2 or 6 h. After 2 or 6 h of conservation, the fragments were randomly fixed, constituting the control (CTR2; CTR6), cultured in vitro (IVC2; IVC6), frozen (SFZ2; SFZ6), or frozen and cultured in vitro (SFZIVC2; SFZIVC6). All fragments were analyzed by classical histology (morphology), immunohistochemistry (PCNA), immunofluorescence (β-catenin), PCRq-RT (Oct4, C- kit, Bax, Bcl-2), transmission (TEM), and scanning (SEM) electron microscopy, respectively. The histomorphological data showed that regardless of the conservation time, whether followed by cryopreservation or not, epithelial (Ealt) and nuclear (Nalt) alterations increased after 48 h of IVC (p<0.05). Immunostaining for β-catenin was lower (p < 0.05) in SFZIVC2 and SFZIVC6 fragments compared with IVC2 and IVC6, respectively. Oct4 expression in SFZ6 was lower than that in CTR6 (p < 0.05). Conversely, C-kit expression was similar among CTR2, CTR6, SFZ2, and SFZ6 fragments. Bax and Bcl-2 expression were also similar among IVC2, IVC6, SFZIVC2, and SFZIVC6 fragments. The Bax/Bcl-2 ratio in IVC2 and SFZIVC6 was higher than that observed in CTR2 and SFZ6, respectively. In conclusion, our results demonstrate that controlling the duration of testicular storage at 4 °C before slow freezing and/or in vitro culture directly affects the viability and quality of testicular tissue, thereby influencing the success of reproductive function preservation.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250139"},"PeriodicalIF":2.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412006/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cooling extender choice modulates the efficacy of freezing extenders for boar sperm cryopreservation.","authors":"Nina Miglioranza Vellozo, Gabriel Augusto Monteiro, Pedro Henrique de Oliveira Baldini, Rogério Araújo de Almeida, José Antônio Dell'Aqua, Frederico Ozanam Papa, Daniella Jorge de Moura, Eunice Oba","doi":"10.1590/1984-3143-AR2025-0174","DOIUrl":"10.1590/1984-3143-AR2025-0174","url":null,"abstract":"<p><p>Boar semen cryopreservation is limited by high sperm sensitivity, with the cooling extender and holding time representing critical steps. However, the interplay between transport and freezing extenders remains poorly elucidated. This study evaluated the main effects and the interaction between two cooling extender (BTS and BSUI®) and two freezing extenders (TRIS® and BBB®) on post-thaw boar semen quality. Ejaculates from 10 boars were processed in a 2x2 factorial design (BTS/TRIS, BTS/BBB, BSUI/TRIS, BSUI/BBB). Sperm kinetics (CASA) and plasma membrane integrity (PMI) were assessed at pre-centrifugation, post-centrifugation, and post-thaw time points. At the post-thaw evaluation, no significant interaction was observed between transport and freezing extenders (P > 0.05), indicating that these factors act independently. Regarding the main effects, the BSUI® cooling extender resulted in superior kinetic performance compared to BTS (P < 0.05). Independently, the TRIS® freezing extender yielded higher motility and membrane integrity than BBB® (P < 0.05). Consequently, the sequential combination of BSUI/TRIS presented the highest absolute kinetic values (Total Motility 63.3%; Progressive Motility 36.1%) due to the cumulative effect of the most efficient extenders. In conclusion, the cooling extender influences post-thaw quality independently of the freezing extender. The BSUI/TRIS sequence optimized post-thaw kinetics through an additive effect. Therefore, protocol optimization should focus on selecting the most efficient extender for each isolated stage of the process.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250174"},"PeriodicalIF":2.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412004/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effectiveness of peri-conception low dose of a highly gluconeogenic fast-release supplement in a fixed-time insemination program on ovarian and reproductive outcomes in meat goats.","authors":"Caroline Pessoa da Silva, César Carneiro Linhares Fernandes, Alfredo José Herrera Conde, Camila Muniz Cavalcanti, Felipe Brener Bezerra de Oliveira, Saul Gaudencio, Juliana Paula Martins Alves, Dárcio Ítalo Alves Teixeira, Davide Rondina","doi":"10.1590/1984-3143-AR2025-0061","DOIUrl":"10.1590/1984-3143-AR2025-0061","url":null,"abstract":"<p><p>This study verified the impact of glycerin supplementation during fixed-time insemination on ovarian and reproductive outcomes in meat goats. Fifty-one Anglo-Nubian crossbred does underwent estrus synchronization with 12 days of CIDR, followed by 0.075 mg of d-cloprostenol and 150 IU of eCG. Thirty-six hours after CIDR removal, 100 μg of GnRH was administered, and 18 h later, insemination (AI) was performed via intrauterine laparoscopy. At CIDR insertion, goats were grouped into the Control Group (n = 25) fed a TMR, and the DGS Group (n = 26), where TMR was supplemented with 100 mL of glycerin from CIDR insertion to two weeks after AI. DGS showed a lower diet intake (-13%; P < 0.001) and higher (+ 5.3%; P = 0.026) glucose levels. In the CIDR interval, DGS pregnant goats (DGSPG), presented in the first wave a higher number of growing follicles (P = 0.035) and greater follicular diameters (P < 0.05). After CIDR removal, the DGSPG exhibited a lesser small follicles (P = 0.016), greater follicle size (P = 0.005), and lower number of corpora lutea (P = 0.031). Pregnancy (32.0% vs. 46.2%) and twinning rates (87.5% vs. 66.7%) were similar in Control and DGS groups (P > 0.05). The control group had a higher proportion of non-pregnant goats that were follicular unresponsive during the CIDR interval (P < 0.01). In pregnant animals, no differences (P > 0.05) were found in fetal biometric measurements, kidding rate, or litter size. Glycerin stimulated follicle growth and CL regression before AI but did not promote reproductive effects post-AI.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250061"},"PeriodicalIF":2.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412002/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148618111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated ultrasonographic, endocrine, seminal, and morphological characterization of cryptorchidism in collared peccary (<i>Pecari tajacu</i>).","authors":"Radan Elvis Matias de Oliveira, Fernanda Loffler Niemeyer Attademo, Alana Ingrid de Araújo Pereira, Euziele Oliveira de Santana, Romário Parente Dos Santos, Luana Grasiele Pereira Bezerra, Alexandre Rodrigues Silva, Moacir Franco de Oliveira","doi":"10.1590/1984-3143-AR2026-0022","DOIUrl":"10.1590/1984-3143-AR2026-0022","url":null,"abstract":"<p><p>Cryptorchidism is a congenital reproductive disorder that can compromise fertility and represents a challenge for conservation and management programs in wildlife species. In collared peccary (<i>Pecari tajacu</i>), reports of this condition are rare and generally limited to imaging findings. This study reports a case of unilateral cryptorchidism in an adult male collared peccary, providing an integrated ultrasonographic, biometric, endocrine, seminal, and morphological characterization. Clinical examination revealed the absence of the left testis in the scrotum, with an inguinal mass suggestive of testicular retention, which was confirmed by ultrasonography. Ultrasonographic evaluation demonstrated a retained testis with reduced size and homogeneous hypoechoic echotexture, whereas the scrotal testis showed increased volume and discrete echotextural alterations. Testicular biometry revealed marked asymmetry between the testes, with reduced length, width, thickness, and volume of the cryptorchid testis compared with the contralateral scrotal testis, which exhibited hypertrophy. Serum testosterone concentration was markedly elevated (15,940 pg/mL), exceeding reference values for the species. Seminal analysis revealed reduced sperm concentration (380 × 10⁶ spermatozoa/mL) compared to healthy individuals, although motility (74%) and sperm morphology (69% normal cells) remained within ranges compatible with fertility. Reduced mitochondrial activity and plasma membrane functionality suggested potential limitations in functional fertility. Histological evaluation demonstrated preserved architecture and complete spermatogenesis in the scrotal testis, whereas the retained testis exhibited tubular atrophy and absence of advanced stages of spermatogenesis. Despite methodological considerations regarding hormonal assessment, the findings support a compensatory hypertrophic and endocrine response of the scrotal testis in unilateral cryptorchidism. This case expands current knowledge on reproductive pathology in collared peccary and highlights the importance of integrated diagnostic approaches for reproductive health assessment and management in captive wildlife populations.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20260022"},"PeriodicalIF":2.3,"publicationDate":"2026-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412000/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonal hydrology and its impact on buffalo artificial insemination strategies in the amazon region of northern Brazil.","authors":"Haroldo Francisco Lobato Ribeiro, Sebastião Tavares Rolim, Satish Kumar, Ana Flavia Bezerra da Silva, Luciana Magalhães Melo, Vicente José de Figueirêdo Freitas, William Gomes Vale","doi":"10.1590/1984-3143-AR2025-0062","DOIUrl":"10.1590/1984-3143-AR2025-0062","url":null,"abstract":"<p><p>This study aimed to verify how seasonal hydrology affects artificial insemination strategies in northern Brazil to promote better livestock management and ecosystem sustainability. A total of 1780 inseminations were analyzed, including 1590 fixed-time artificial inseminations (FTAI) and 190 conventional artificial inseminations (CAI) (AI in natural estrus without using hormones) conducted over ten years. Of these, 370 inseminations occurred during the flood season (January to May), 700 during the intermediate season (June to September), and 710 during the ebb season (October to January). The estrus synchronization protocols were utilized according the ovarian cyclicity of buffaloes, i.e.: Protocol I (Ovsynch), was used for cycling buffaloes; Protocol II (Ovsynch-P₄); Protocol III (CL-synch), for the buffaloes with a mature corpus luteum (CL); Protocol IV (P₄ + BE) + (PGF_2α + eCG) + GnRH and Protocol V (P₄ + VE) + (PGF_2α + eCG) + BE were implemented for buffaloes in anestrus, with low body condition, or during unfavorable seasons. AI was performed using cryopreserved-thawed semen. Pregnancy diagnosis was performed using ultrasonography or rectal palpation between 45 and 90 days after insemination. A higher pregnancy rate was observed for the PI (66.87%) than for II (53.77%), III (52.41%), IV (53.35%) and V (33.17%). Regarding seasons, the overall pregnancy rate (53.14%) for FTAI was significantly higher (<i>P</i> < 0.05) than CAI (27.4%). During the season of Full tide, Intermediary and Ebb tide, the percentage of pregnancy rate for FTAI vs CAI was 48.28 vs 20.00, 47.77 vs 10.00 and 61.47 vs 41.00, respectively. The pregnancy rate was significantly higher during ebb tide for both FTAI/CAI than in other seasons. In conclusion, seasonal hydrology impacts the outcome of AI strategies in buffaloes in the Amazon region of northern Brazil. A suitable synchronization protocol can enhance buffalo fertility and improve agricultural practices.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250062"},"PeriodicalIF":2.3,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412008/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spawning of pacu, <i>Piaractus mesopotamicus</i>, at two different times, with a focus on melatonin levels and reproductive performance.","authors":"Rafael Tomoda Sato, Mariana Roza de Abreu, Laíza Maria de Jesus Silva, Cristiane Fernanda Benevente, Sergio Ricardo Batlouni","doi":"10.1590/1984-3143-AR2025-0024","DOIUrl":"10.1590/1984-3143-AR2025-0024","url":null,"abstract":"<p><p>Melatonin (MTN) plays a direct role in fish ovulation, and we hypothesized that aligning ovulation with an endogenous MTN peak levels could improve reproductive performance. To that, in experiment 1, we assessed circadian variation of plasma MTN in pacu (<i>Piaractus mesopotamicus</i>) females. In experiment 2, pacu females were divided into two groups: one receiving the hypophysation dose at 7 pm (dark onset) and the other at midnight (five hours after dark). Experiment 1 showed that circulating MTN levels increased at 7 pm and remained stable through the dark phase. In experiment 2, no differences in latency or reproductive performance were observed between groups. However, MTN levels at ovulation increased significantly only in the 7 pm group. Strong positive correlations between MTN levels at ovulation and reproductive parameters, such as fertility, hatching rates, and fecundity, were observed. These results confirm that PGF2α and DHP peaks at ovulation are associated with successful ovulation in pacu, consistent with literature that shows that MTN influences ovulation by acting through the Mtnr1a receptor, triggering arachidonic acid release and prostaglandin synthesis. Our findings indicate that the timing of spawning induction influences MTN levels at ovulation, which are positively correlated with reproductive success. This is the first report linking plasma MTN levels at ovulation to successful reproductive performance in fish induced by hypophysation, highlighting the relevance of spawning timing for pacu reproduction.</p>","PeriodicalId":7889,"journal":{"name":"Animal Reproduction","volume":"23 3","pages":"e20250024"},"PeriodicalIF":2.3,"publicationDate":"2026-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13412116/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148617999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}