Resumo em Inglês:

Abstract The anti-Mullerian hormone (AMH) or Mullerian Inhibiting Substance (MIS), produced by the Sertoli cells induces the regression of Mullerian ducts in male embryos. Granulosa cells from ovarian follicle are homologous to Sertoli cells and produce AMH. The aim of this study was the immunolocalization of AMH in the testicles and ovaries of bovine fetuses at different ages. Gonads from bovine fetuses between 4 and 7 months (24-98 CRL) were collected in a local slaughterhouse, fixed in 10% formaldehyde, and processed for conventional histology and embedded in paraffin cut with a rotative microtome, deparaffinized, and subjected to immunohistochemistry using the anti- AMH 1:50 (SC 28912, Santa Cruz Biotechnology) according to the manufacturer's instructions. Immunostaining was observed in the cytoplasm of Sertoli cells, within the sexual cords (developing seminiferous tubules) at all ages and was not observed in gonocytes and interstitial tissue. In the ovary there was light staining in granulosa cells but not in the theca cells, however, intense staining was observed in the cytoplasm of the oocyte of primordial, primary, secondary and antral follicles, at all ages analyzed, suggesting that despite being produced by granulosa cells, AMH concentrates in the oocyte cytoplasm. The importance of AMH in sexual differentiation and action in Muller's ducts is well understood, however there are no studies on the role of this protein in gonadal development, this being the first report of AMH immunolocalization in fetal bovine testis and ovaries, requiring further studies on the action and importance of AMH in the gonadal development of bovine fetuses.

Resumo em Inglês:

Abstract Colostrogenesis and lactogenesis influenced by age require further understanding in Zebu herds, due to the longevity of breeding cows. Thus, we aimed to compare colostrum and milk physicochemical and proteinogram of Dairy Gir cows and calves’ passive immunity transfer by grouping 28 cows and their calves by maternal age: Young (n=6; aged 24-36 months), Adult (n=15; 37-91 months) and Senior (n=7; 96-137 months) groups. Colostrum and milk were collected at first milking (immediately after calving), transition milk (3rd milking, after 24h of calving) and full milk (10th milking, after 5 days of calving) for analysis of density, total solids, pH, immunoglobulin (IgG) and proteinogram (lactoferrin, albumin, heavy and light chain IgG, β-lactoglobulin and α-lactalbumin). Calves’ blood was collected after 3 days of birth to evaluate serum total solids, total protein, liver profile, light and heavy chain IgG. Data were statistically analyzed by LSD Test at P<0.05. Young Group had higher (P<0.05) colostrum total solid and density compared to Senior Group. Transition milk of young cows had lower (P<0.05) pH than seniors. Calves of senior cows presented higher (P<0.05) serum albumin than young and adult. Young cows had IgG decrease from colostrum to transition milk, whereas adult cows presented fall (P<0.05) of IgG throughout milking. In conclusion, age of Dairy Gir cows does not affect colostrum and milk immunological quality, nor calves’ immunity transfer. However, it determines protein composition and dynamic changes, especially in young and senior cows.

Resumo em Inglês:

Abstract Postpartum uterine disease is a major cause of impaired bovine reproduction and is usually managed with intrauterine antibiotics. Alternative non‑antibiotic therapy is needed to support uterine health without contributing to antimicrobial resistance. The goal of this study was to characterize histomorphometric and ultrastructural changes of the bovine endometrium after intrauterine infusion of ozonated sunflower oil during early puerperium, and to assess its in vitro antimicrobial activity against uterine bacteria. Eighteen primiparous cows received a single intrauterine treatment with ozonated or non‑ozonated oil (O3 and non‑O3 groups; n=9/group) on day 10 postpartum. Endometrial biopsies were collected before and 15 days post-treatment (D0 and D15) for light microscopy and scanning electron microscopy. Uterine cytology was used to evaluate subclinical endometritis. Minimum inhibitory and bactericidal concentrations (MIC and MBC) of the treatments were determined against uterine isolates (Escherichia coli, Staphylococcus spp., Streptococcus spp. and Arcanobacterium pyogenes). At D15, the number of endometrial glands was higher in the O3 group than in the non‑O3 group (32.6±2.5 vs. 11.0±1.0; P<0.01), whereas glandular diameter, luminal area and cell number per gland were lower in O3 cows (P<0.01), indicating enhanced gland proliferation with reduced glandular dilatation. No degenerative histopathological changes, such as periglandular fibrosis or endometrial atrophy, were detected in either group, and scanning electron microscopy showed preserved apical ultrastructure without adverse effects of ozonated oil. Ozonated oil inactivated all uterine bacteria (MIC and MBC ≤0.18 µg mL‑1), while non‑ozonated oil showed no antimicrobial activity. Both groups showed a marked reduction in neutrophil percentage by D15, but histological evidence of persistent inflammation was more pronounced in non‑O3 cows. These findings indicate that intrauterine ozonated sunflower oil is a promising non‑antibiotic therapy to support postpartum uterine involution and endometrial recovery in dairy cows and may contribute to improved reproductive performance.

Resumo em Inglês:

Abstract 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 (Piaractus mesopotamicus) 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.

Resumo em Inglês:

Abstract 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) + (PGF2α + eCG) + GnRH and Protocol V (P4 + VE) + (PGF2α + 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 (P < 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.

Resumo em Inglês:

Abstract This study aimed to characterize the antibiofilm action of ozone-enriched sunflower oil (O3) against pathogens associated with endometritis in mares. Initially, samples from 41 mares with a history of subfertility were stored in BHI broth and 0.9% NaCl solution. The samples underwent microbial culture, identification, and in vitro sensitivity testing at LABRAPE-UFRPE, Brazil. Biofilm production was evaluated by the crystal violet method. Subsequently, biofilm-forming bacteria were subjected to the action of different concentrations of ozonated sunflower oil. Of the 21 isolates tested for biofilm production, 76.2% (16/21) showed positive production, with 43.75% (7/16) being weak producers, 31.25% (5/16) moderate producers, and 25% (4/16) strong producers. After the action of ozonated sunflower oil at a concentration of 203.43 mEq/L, a reduction was observed in the mass of the gram-negative bacilli biofilm, however, no statistical difference was found for the gram-positive cocci biofilm. The results show that ozonated sunflower oil presented satisfactory results in breaking down gram-negative bacteria biofilm.

Resumo em Inglês:

Abstract 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.

Resumo em Inglês:

Abstract 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.

Resumo em Inglês:

Abstract Artificial insemination (AI) is a key biotechnology applied to disseminate superior genetics; however, its success depends on skilled labor to ensure accurate and consistent execution. A semi-automated insemination system (SAIS), capable of controlling semen deposition and reproducing the pressure of natural mating, can align AI procedures more closely with the sow’s physiological responses. The objective of this study was to evaluate whether the use of SAIS in post-cervical AI can improve reproductive efficiency in sows. A total of 449 females were inseminated, with 228 sows assigned to SAIS and 221 to the conventional method (CONV). Groups were balanced for parity, body condition, inseminator, and boar distribution. Sperm quality during storage did not differ between treatments. However, significant differences emerged during AI procedures: the SAIS group required less time to perform AI (18.60 ± 5.65 vs. 22.52 ± 12.38 seconds; P < 0.0001) and presented a lower incidence of semen backflow after AI (43.28% vs. 66.15%; P < 0.0001). The backflow negatively affected conception rate (P = 0.0342), although it did not influence total or live-born piglet numbers. Regarding reproductive performance, conception and farrowing rates were similar between groups. Nevertheless, females inseminated with SAIS have a higher total number of piglets born (16.97 ± 3.38 vs. 15.70 ± 3.91; P = 0.0027) and more live-born piglets (15.79 ± 3.3 vs. 14.46 ± 3.6; P = 0.0016) compared with CONV. Since backflow was not associated with litter size, this improvement cannot be attributed solely to reduced reflux. Instead, factors such as more standardized semen deposition and lower variability between inseminations may have contributed to this improvement. In conclusion, SAIS proved to be a practical and advantageous tool for AI in sows. Its use reduced time, decreased backflow, and increased litter size, representing a promising strategy to enhance efficiency in commercial herds.

Resumo em Inglês:

Abstract 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.

Resumo em Inglês:

Abstract 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 (Pecari tajacu), 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.

Resumo em Inglês:

Abstract 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 (p < 0.05) between cells assessed immediately after thawing and those assessed at confluence. Upon reaching confluence, there was no significant difference (p > 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.

Resumo em Inglês:

Abstract Our study explored the histological and histo-functional characteristics of the testis and seminal vesicles of Jaculus jaculus, 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 Jaculus jaculus, 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.

Resumo em Inglês:

Abstract The objective of this study was to evaluate the antioxidant properties of Moringa oleifera hay and the effects of its dietary inclusion on the reproductive potential of rams. Twenty-eight adult rams, with a mean age of two years and an average body weight of 69.36 ± 1.29 kg, were randomly allocated into four experimental groups (G) and subjected to isoproteic diets composed of 30% concentrate (corn, soybean meal, and urea), sorghum silage (SS), and MOH in different proportions: G0 (control: 0% MOH, 70% SS); G10 (10% MOH, 60% SS); G20 (20% MOH, 50% SS); G30 (30% MOH, 40% SS), along with ad libitum water. Semen collections were performed every 15 days for seminal and sperm evaluations. M. oleifera (MO) hay was analyzed for total phenolic compounds, flavonoid content, and in vitro antioxidant capacity and was compared with fresh MO. Total antioxidant capacity of seminal plasma was determined using the ferric reducing antioxidant power (FRAP) assay. MOH did not differ from MO in total phenolic content (33.38 vs. 33.64mg GA Eq/g), but its flavonoid content was higher (4.75 vs. 3.88 mg CAT Eq/g). DPPH (802.00 vs. 1840.38 µg/mL), ABTS (1091.78 vs. 2943.82 µg/mL), and FRAP (418.08 vs. 146.83 mg/mL) The results indicated greater antioxidant and reducing capacity in MO hay. No differences were observed among groups regarding total antioxidant capacity of seminal plasma or conventional seminal parameters (P> 0.05). However, regardless of the inclusion level, groups supplemented with MO hay showed a higher percentage of sperm plasma membrane integrity (P < 0.05) compared with the control group at all evaluation time points. It is concluded that the haymaking process enhances the antioxidant capacity of MO and that its inclusion in the diet of rams improves sperm plasma membrane integrity, positively reflecting semen quality. Thus, the use of MO hay may be considered a promising nutritional strategy to increase the reproductive potential of rams.

Resumo em Inglês:

Abstract Highly conserved vertebrate molecular markers, such as Gfra1, Pou5f3, Notch1, Plzf, and Nanos2, represent important candidates for evaluating spermatogonial stem cells (SSCs) physiology and preferential location in the fish testis. In tilapia, germ cell cysts are distributed within seminiferous tubules oriented along the dorso–ventral axis, while the adult testis continues to grow along both the longitudinal (cranio–caudal) and dorso–ventral axes. Herein we investigated the spatial distribution of undifferentiated spermatogonia (Aund) expressing established SSC-associated markers in the testes of sexually mature Nile tilapia. Topographical analysis along the longitudinal axis showed that Aund were predominantly located in regions of the seminiferous tubules adjacent to the interstitial compartment, with approximately 53% of Aund in the caudal region and 18% in the cranial region of the testis. Accordingly, most Aund positive for Gfra1, Plzf, and Nanos2 (>70%; p<0.05) were preferentially detected in the caudal region. Analysis along the dorso–ventral axis showed that Aund positive for Plzf, Gfrα1, Nanos2, Nanos1, Notch1, and Notch3 were more frequently observed in areas closer to the tunica albuginea compared with regions adjacent to the efferent ducts. Together, these findings demonstrate pronounced regional differences in the distribution of Aund along both the cranio–caudal and dorso–ventral axes of the Nile tilapia testis, highlighting a spatially organized germinal architecture that may be relevant for the maintenance of the germinal epithelium and post-pubertal testicular growth. To our knowledge, this is the first study to systematically describe the spatial distribution of Aund-associated markers in a teleost species.

Resumo em Inglês:

Abstract This study investigated the patterns of sperm kinetics in two fish species, Piaractus mesopotamicus and Pseudoplatystoma reticulatum and their relationship with seminal quality. Semen samples were collected after hormonal induction, with the aim of identifying indicators of seminal quality and their relationship with reproductive success. The results revealed marked interspecific differences: P. reticulatum exhibited longer-lasting motility (83 ± 31 s) with stable linear movement patterns after activation, while P. mesopotamicus showed more intense but shorter-lasting motility (41 ± 8 s), exhibiting initial circular trajectories that transitioned to linear patterns. In P. reticulatum, positive correlations were found between total motility (MOT), progressivity (PROG), velocities: curvilinear (VCL), straight-line (VSL) and average (VAP), with hatching rate (HR). These are suggested to be reliable predictors of seminal quality. For P. mesopotamicus, multivariate analysis (PCA) indicated that sperm quality was associated with a specific combination of VCL, VAP, and amplitude and lateral displacement of the head (ALH), although no single parameter was directly correlated with HR. These differences reflect distinct evolutionary adaptations to their lotic reproductive environment, associated with effective oocyte fertilization capacity and larval hatching rate. P. mesopotamicus is adapted for rapid fertilization, with higher sperm speed, while P. reticulatum demonstrates more sustained sperm motility. These results highlight the need for species-specific approaches and demonstrate that the simple evaluation of sperm kinetic parameters in fish does not allow seminal qualification, requiring detailed knowledge of sperm movement by species, essential information to optimize the nutritional and reproductive management of breeders, and seminal cryopreservation protocols.

Resumo em Inglês:

Abstract Gonadectomy, the surgical removal of reproductive organs—is commonly practiced in canine management and is often associated with responsible pet ownership. Although advised for preventing unwanted litter and specific health hazards, its effects on canine behavior remain contentious and little studied. This article analyzes the physiological and behavioral effects of gonadectomy in dogs, emphasizing other sexually dimorphic behaviors including mounting, wandering, and urine marking, alongside aggression, fear, anxiety, separation-related issues, and canine cognitive dysfunction. Gonadectomy impacts hormonal equilibrium by modifying the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes, hence affecting stress responses, cognition, and behavior. Certain research indicates that neutering diminishes urine marking and roaming; nevertheless, the results are inconsistent. Conflicting research suggests that gonadectomy may intensify aggression, fearfulness, and anxiety, thus undermining the human-animal bond. The effects of gonadectomy on cognitive impairment remain ambiguous. Alternative methods, including vasectomy, ovary-sparing spay, and chemical castration, provide reproductive regulation while maintaining hormonal function, potentially alleviating negative behavioral consequences. Due to the complex aspects of behavioral development, encompassing heredity, environment, and personal experiences, a general policy on gonadectomy is unsuitable. This review highlights the necessity of personalized assessments when advising gonadectomy for behavioral management in canines. Veterinarians must meticulously evaluate the advantages and disadvantages, considering the unique circumstances of each animal and seeking guidance from veterinary behaviorists, as necessary. Routine desexing should not be universally advocated only for the purpose of mitigating behavioral issues. Additional research is crucial to comprehend the intricate link between gonadectomy and canine behavior.