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Simple Summary: The timing of ovulation varies widely among gilts, leading farms to often perform multiple inseminations to ensure that sperm and eggs meet in the reproductive tract, thus enhancing fertility. Administering a gonadotropin-releasing hormone (GnRH) agonist, such as buserelin, at the onset of estrus can induce ovulation and reduce the variation in ovulation timing among sows. This study examined the effect of adding buserelin to boar semen on the litter size of gilts. Gilts were inseminated with semen enriched with either 5 or 10 µg of buserelin acetate during the initial insemination. Although there were no significant differences in the farrowing rate between the groups, the group receiving 10 µg of buserelin acetate had a higher total number of piglets and live-born piglets. Additionally, this group exhibited greater litter birth weight compared to the control group. These findings indicate that supplementing boar semen with a GnRH agonist enhances litter size in gilts. The use of exogenous hormones has long been of interest for improving reproductive performance in swine production. Enhancing litter size directly impacts the economic efficiency of pig production. Various strategies, including nutritional, genetic, and hormonal approaches, have been explored with varying degrees of success. Administering a gonadotropin-releasing hormone (GnRH) agonist, such as buserelin, at the onset of estrus can induce ovulation and reduce the variation in ovulation timing among sows. This study assessed the impact of GnRH agonist supplementation in boar semen doses on the litter size of inseminated gilts. The research was conducted on a commercial swine herd in northern Thailand. A total of 231 Landrace × Yorkshire crossbred gilts, aged 224.5 ± 16.2 days at the onset of estrus synchronization, participated in the experiment. The gilts' estrus was synchronized with oral altrenogest supplementation at a dosage of 20 mg/day for 18 days. After exhibiting standing estrus, the gilts were randomly divided into three groups. Control group: gilts were inseminated at 0 and 12 h post standing estrus onset with a conventional semen dose (n = 94). Treatment 1: similar to the control group, but with an added 5 µg (1.25 mL) of buserelin acetate to the boar semen dose during the first insemination (n = 71). Treatment 2: similar to the control group, but with 10 µg (2.5 mL) of buserelin acetate added to the boar semen dose during the first insemination (n = 66). All gilts were inseminated twice during their standing estrus using the intrauterine artificial insemination method. Each semen dose contained 3.0 × 109 motile sperm in 80 mL. The farrowing rate averaged 78.8% and did not significantly differ between the groups (p = 0.141). The total number of piglets born per litter in the treatment 2 group was greater than in the control group (14.0 ± 0.3 vs. 13.2 ± 0.3, respectively, p = 0.049), but was not significantly different from the treatment 1 group (13.3 ± 0.3, p = 0.154). Similarly, the number of live-born piglets in the treatment 2 group was greater than in the control and treatment 1 groups (13.2 ± 0.4 vs. 12.3 ± 0.3 and 12.0 ± 0.4, respectively, p < 0.05). Moreover, the live-born piglets' litter birth weight in the treatment 2 group was greater than in the control group (17.0 ± 0.4 vs. 15.6 ± 0.3 kg, respectively, p = 0.008) and the treatment 1 group (15.7 ± 0.4 kg, p = 0.025). In conclusion, adding a GnRH agonist to boar semen appears to enhance the litter size of gilts. Further research should focus on understanding the underlying mechanisms and determining the optimal dose and timing for GnRH agonist supplementation. [ABSTRACT FROM AUTHOR]

The present study investigated factors associated with the incidence of stillbirth in young hyper‐prolific sows within free farrowing systems in tropical environments. A total of 714 live‐born and 54 stillborn piglets from 57 Landrace × Yorkshire sows, with an average parity of 2.7 ± 1.0 (range: 1 – 4), were comprehensively investigated. Reproductive variables of the sows, including gestation length, farrowing duration, the total number of piglets born per litter, and the birth order and status of each piglet, were recorded. Differences in the physiological characteristics of live‐born and stillborn piglets, such as birth interval, cumulative birth interval, body weight at birth, crown‐rump length, body mass index (BMI), ponderal index (PI), meconium staining score, and the percentage of piglets with a broken umbilical cord, were analysed. Piglets were divided into four groups based on the quartiles of birth order (Q1–Q4). On average, the duration of farrowing was 173.3 ± 85.9 min, and the total number of piglets born and number of piglets born alive‐per litter were 14.1 ± 3.8 and 12.5 ± 3.5, respectively. The incidence of stillbirth was 6.7% (54/801 piglets). The higher percentages of stillbirths were detected in sows with large litter sizes (≥17 piglets, 10.9%) compared to those with small (≤13 piglets, 6.1%) and moderate (14 – 16 piglets, 2.8%) litter sizes (p <.001). The incidences of stillbirth in Q3 and Q4 of the litters were higher than in Q1 and Q2 (p <.001). Compared to live‐born piglets, stillborn piglets had higher cumulative birth interval (103.0 ± 3.71 vs. 142.4 ± 9.35 min, p <.001), BMI (17.1 ± 0.15 vs. 18.4 ± 0.39 kg/m2, p =.002), PI (63.7 ± 0.59 vs. 70.8 ± 1.59 kg/m3, p <.001), meconium staining scores (1.78 ± 0.04 vs. 2.04 ± 0.10, p =.021), and the percentage of piglets born with a ruptured umbilical cord (45.2% vs. 66.0%, p =.004). An increase in the incidence of stillbirth was detected at 60, 120, 150, 180, and ≥ 210 min after the first piglet was born, compared to those born within the first 30 min of farrowing (p <.05). In conclusion, the study found that stillbirths in young, hyper‐prolific sows were linked to several factors: large litter sizes (≥17 piglets per litter), prolonged cumulative birth intervals (142.4 min), elevated BMI of 18.4 kg/m2, high PI values of 70.8 kg/m3, increased meconium staining scores, and a higher occurrence of ruptured umbilical cords. To reduce the risk of stillbirth, particularly among piglets with high body indices born later in the birthing process, it is recommended to enhance farrowing supervision for young sows, starting at a cumulative birth interval of 60 min. [ABSTRACT FROM AUTHOR]

Melatonin, an endogenous indolamine derived from tryptophan, is primarily synthesized by the pineal gland in mammals and regulated by a complex neural system. Its release follows a circadian rhythm, which is crucial for regulating physiological processes in response to light–dark cycles in both humans and animals. In this review, we report that the presence of this hormone in bovine milk, with significant differences in concentration between daytime and nighttime milking, has increased interest in milk as a natural source of bioactive molecules. Melatonin lowers cortisol levels at night, reduces body temperature and blood pressure, coinciding with decreased alertness and performance, acts as an antioxidant and anti-inflammatory agent, modulates the immune system, offers neuroprotective benefits, and supports gastrointestinal health by scavenging free radicals and reducing oxidative stress in dairy cows. Many factors influence the release of melatonin, such as the intensity of artificial lighting during nighttime milking, the frequency of milkings, milk yield, and genetic differences between animals. Nocturnal milking under low-intensity light boosts melatonin, potentially reducing oxidative damage and mastitis risk. Additionally, ultra-high temperature (UHT) treatment does not significantly affect the melatonin content in milk. However, further research on its stability during milk processing and storage is crucial for ensuring product efficacy. In some countries, nighttime milk with naturally elevated melatonin content is already commercialized as a natural aid for sleep. Thus, naturally melatonin-rich milk may be a promising alternative to synthetic supplements for promoting better sleep and overall well-being. [ABSTRACT FROM AUTHOR]

Simple Summary: Today, sows produce larger litter sizes than they did several years ago. Modern hyperprolific sows with greater parity numbers experience longer farrowing durations and require more farrowing assistance compared to those with lower parity numbers. Among reproductive hormones, oxytocin plays a critical role during parturition and is often given to sows during farrowing to shorten its duration. Oxytocin is a uterotonic hormone originating from the hypothalamus and released from the posterior pituitary gland, and it is important for the expulsion of fetuses. Aging is a well-known factor that affects productivity and increases farrowing duration in modern prolific sows. In the current study, we demonstrated a decrease in the immunolocalization of oxytocin receptors in the uterine tissue of older sows, supporting a previous study that showed weaker uterine contractions in sows with a greater parity number, which possibly affects the duration of farrowing. This study investigated the gross morphology of reproductive organs and oxytocin receptor distribution across different parities in hyperprolific sows. A total of thirty-two reproductive organs from Landrace × Yorkshire crossbred sows were categorized into three groups based on parity numbers: 1 (n = 10), 2–5 (n = 12), and ≥6 (n = 10). All sows were culled due to management problems, and none had reproductive disorders. A gross morphology examination of the ovaries, uterus, and the rest of the reproductive tract was conducted. Using immunohistochemistry, the levels of oxytocin receptor were evaluated in five layers of the uterus, the epithelial, superficial glandular, deep glandular, and circular and longitudinal smooth muscles of the myometrium, and were quantified using an H-score. On average, the age and body weight of sows and the total number of piglets born per litter were 799.8 ± 327.8 days, 213.2 ± 31.7 kg, and 15.5 ± 4.8, respectively. The numbers of ovulations in sows in parity number 1 (19.9 ± 2.4) were lower than those in sows in parity numbers 2–5 (29.7 ± 2.0, p = 0.004) and ≥6 (27.7 ± 2.1, p = 0.022). The uterine weights of sows in parity number 1 (902.9 ± 112.5 g) were lower than those of parity numbers 2–5 (1442.1 ± 111.8 g, p = 0.001) and ≥6 (1394.3 ± 125.1 g, p = 0.004). The length of the uterus in sows with parity number 1 (277.9 ± 26.1 cm) was shorter than those in sows with parity numbers 2–5 (354.6 ± 25.9 cm, p = 0.033) and tended to be shorter than those in sows with parity numbers ≥ 6 (346.6 ± 29.0 cm, p = 0.068). The immunolocalization of oxytocin receptors could be detected in various parts of the porcine endometrium and myometrium. Among the five tissue layers of the uterus, the H-score of oxytocin receptors in the deep uterine glands was greater than in the superficial uterine glands (p = 0.023) and the circular muscle layer of the myometrium (p = 0.011), but it did not differ from the epithelial layer of the endometrium (p = 0.428) or the longitudinal muscle layer of the myometrium (p = 0.081). Sows with parity numbers ≥ 6 had a lower oxytocin receptor H-score than those with parity numbers 1 (p < 0.001) and 2–5 (p < 0.001). In conclusion, these data emphasize the notable variations in several reproductive parameters and the levels of oxytocin receptor within the uterus of hyperprolific sows. Across the majority of uterine tissue layers, there was a marked decrease in the H-score of the oxytocin receptor in the older sows. [ABSTRACT FROM AUTHOR]

This study aims to investigate bacterial communities and antimicrobial resistance (AMR) in airborne dust from pig farms. Airborne dust, pig feces and feed were collected from nine pig farms in Thailand. Airborne dust samples were collected fromupwind and downwind (25meters frompig house), and inside (in themiddle of the pig house) of the selected pig house. Pig feces and feed samples were individually collected from the pen floor and feed trough from the same pig house where airborne dust was collected. A direct total bacteria count on each sampling plate was conducted and averaged. The ESKAPE pathogens together with Escherichia coli, Salmonella, and Streptococcus were examined. A total of 163 bacterial isolates were collected and tested for MICs. Pooled bacteria from the inside airborne dust samples were analyzed using Metagenomic Sequencing. The highest bacterial concentration (1.9-11.2 × 10³ CFU/m³) was found inside pig houses. Staphylococcus (n = 37) and Enterococcus (n = 36) were most frequent bacterial species. Salmonella (n = 3) were exclusively isolated from feed and feces. Target bacteria showed a variety of resistance phenotypes, and the same bacterial species with the same resistance phenotype were found in airborne dust, feed and fecal from each farm. Metagenomic Sequencing analysis revealed 1,652 bacterial species across all pig farms, of which the predominant bacterial phylum was Bacillota. One hundred fifty-nine AMR genes of 12 different antibiotic classes were identified, with aminoglycoside resistance genes (24%) being the most prevalent. A total of 251 different plasmids were discovered, and the same plasmid was detected in multiple farms. In conclusion, the phenotypic and metagenomic results demonstrated that airborne dust from pig farms contained a diverse array of bacterial species and genes encoding resistance to a range of clinically important antimicrobial agents, indicating the significant role in the spread of AMR bacterial pathogens with potential hazards to human health. Policy measurements to address AMR in airborne dust from livestock farms are mandatory. [ABSTRACT FROM AUTHOR]

Premating maternal nutrition is crucial for postweaning follicle growth, thereby influencing piglet birth weight in subsequent litters. The present study investigated the impact of supplementing a carbohydrate-rich premating diet in sows on metabolic hormones, subsequent piglet birth weight and reproductive performance. Sows were distributed into three groups, control (n=42) received standard diets; treatment I (n=41) received the same diets supplemented with 500 g of a carbohydrate-rich premating diet from weaning until insemination; treatment II (n=42) received the same diets supplemented with 500 g of a carbohydrate-rich premating diet from 7 days before weaning until insemination. Blood samples were taken from sows around weaning to measure serum insulin-like growth factor-1 and insulin, and blood glucose after feeding. The study found that sows on a carbohydrate-rich diet (treatment II) had higher postprandial glucose (P<0.05) and insulin levels (P=0.06) than others. This diet did not affect overall reproductive performance, but it did increase piglet birth weight and reduce the number of low-birth weight piglets compared to the control (P<0.001) and treatment I groups (P<0.05). Supplementing a carbohydrate-rich premating diet for 7 days before weaning until insemination enhanced postprandial glucose and insulin concentrations in weaned sows. This dietary intervention led to improved subsequent piglet birth weight and reduced the proportion of low-birth weight piglets. [ABSTRACT FROM AUTHOR]

Objective: This study evaluated the effect of Andrographis paniculata (A. paniculata) supplementation in sow diets before and after farrowing on the sow and piglets' performances during early postpartum period and on sows' backfat and longissimus muscle losses during lactation. Methods: Seventy Landrace×Yorkshire sows and their offspring (1,186 piglets) were distributed into three groups: control (n = 31), treatment-250 (n = 18), and treatment-1000 (n = 21). From 110.2±0.7 days of gestation until farrowing (5.8 days) and throughout the lactation period (25.2 days), sows in the control group were given the conventional lactation diet, while sows in the treatment-250 and treatment-1000 groups received supplements of 250 ppm and 1,000 ppm of A. paniculata, respectively. Results: In sows with parity 3-5, piglets from the treatment-1000 group had higher colostrum intake than the control and treatment-250 groups (p<0.05), but not in sows with parity 6-9. Colostrum immunoglobulin G (IgG) increased in treated sows versus controls for parity 6-9 (p<0.05), but was consistent for parity 3-5. Piglet performance until day 3 postnatal was similar across groups (p>0.05). Treatment-250 sows had higher feed intake post-farrowing than treatment-1000 sows (p<0.05). Longissimus loss was less in both treatment groups than control (p<0.05), but backfat loss was similar across groups (p>0.05). Post-partum complications were consistent across groups (p>0.05). Farrowing duration and piglet birth intervals in sows with parity 6-9 were prolonged in the treatment-1000 group. Conclusion: Supplementing with 1,000 ppm A. paniculata for 5.8 days pre-farrowing and 25.2 days post-farrowing enhanced sow colostrum IgG and piglet colostrum intake, while also reducing longissimus loss in sows. However, for sows of parity 6-9, this supplementation led to prolonged farrowing, increased intervals between piglet births, increased stillbirth, and reduced piglet birth weight. These effects should be considered when using A. paniculata supplementation. [ABSTRACT FROM AUTHOR]

Simple Summary: This review delves into the oestrus-to-ovulation interval, the potential for ovulation time prediction, and the optimal timing for insemination in dairy cows. Typically, oestrus lasts 10–20 h in dairy cows, with variations attributed to oestrus detection methods and observation frequency. Most cows ovulate around 24–33 h after oestrus onset and 15–22 h after the end of oestrus. The interval from the preovulatory luteinising hormone (LH) surge to ovulation range is approximately 21–30 h, with ovulation occurring at a follicle diameter averaging 18–20 mm. Correctly identifying oestrus onset allows for efficient artificial insemination using the "a.m.–p.m. rule". However, excessively long or short oestrus-to-ovulation intervals may compromise fertility. Heat stress during warm seasons can increase the variability of the oestrus-to-ovulation interval. In cases where insemination timing risks being too early or late relative to ovulation, GnRH administration may be considered to optimize fertility outcomes. This review describes the oestrus-to-ovulation interval, the possibility of predicting the time of ovulation, and the optimum time for insemination relative to oestrus in dairy cows. The duration of oestrus in dairy cows is approximately 8–20 h, with differences possibly related to the methods of oestrus detection and the frequency of observations. Most cows ovulate approximately 24–33 h after the onset of oestrus and 15–22 h after the end of oestrus. The interval from the preovulatory luteinising hormone (LH) surge to ovulation is approximately 4–30 h. Ovulation occurs when follicle diameter averages 18–20 mm. When it is possible to correctly determine the beginning of oestrus, artificial insemination can be performed utilizing the "a.m.–p.m. rule", and only one insemination may be applied. In cows with too long or too short oestrus-to-ovulation intervals, fertility can be compromised. One important factor that can alter the oestrus-to-ovulation interval is acute or chronic heat stress during the warm season. When there is a risk that insemination may occur too early or too late with respect to the time of ovulation, GnRH administration can be considered. [ABSTRACT FROM AUTHOR]

Simple Summary: The current research evaluated the impact of adding dietary fiber to sows during the transitional phase, specifically examining its effects on constipation, the farrowing process, colostrum production, and the mortality of piglets before weaning within a free-farrowing system. Administering 75 g/day of dietary fiber to sows for 7 days before farrowing, especially in those with larger litters, showed a decrease in constipation rates and a reduction in the time taken for farrowing. Additionally, this fiber supplementation resulted in lower mortality rates in piglets prior to weaning. However, this addition of fiber did not improve the production of colostrum and milk, nor did it increase the consumption of colostrum by piglets. These results suggest that in a free-farrowing system, providing sows with dietary fiber during the transitional period can alleviate constipation and shorten the duration of farrowing. Nevertheless, it is advisable to manage the body condition of sows before farrowing to address issues like constipation effectively and to boost colostrum intake. This study investigated how dietary fiber supplementation during the transition period in sows affects constipation, farrowing duration, colostrum production, milk yield, and pre-weaning piglet mortality in the free-farrowing system. A total of 92 Landrace × Yorkshire sows and their 1272 offspring were included in the study. Sows were divided into two groups by parity: control (n = 41) and treatment (n = 51). The control group was fed a standard lactation diet 7 days before farrowing, whereas the treatment group received the same diet with 75 g/day of a dietary fiber supplement. The dietary fiber content analyses were 4.30% and 5.53% in the control and treatment groups, respectively. Sows were fed with 3.89 ± 0.92 kg per day with a diet containing 17.8% crude protein, 3732 kcal/kg of metabolizable energy, and 1.1% lysine. Parameters including farrowing duration, litter characteristics, and the fecal condition of sows were measured. Piglet mortality rates were recorded at 3, 7, and 21 days of lactation. Sows had an average farrowing duration of 216 ± 159 min, with litter sizes of 13.8 ± 4.2 piglets per litter, and a 7.4% stillbirth rate. The treatment group showed a lower constipation rate compared to the control group (17.6% vs. 46.3%, p = 0.003). Farrowing duration did not significantly differ between groups, but the treatment group experienced a 43.6 min shorter duration. In sows with litter sizes of ≥16 piglets per litter, the farrowing duration for sows in the treatment group tended to be shorter than that of the control groups (202.0 ± 37.9 vs. 287.5 ± 41.3 min, p = 0.115). The mean colostrum intake of piglets in the control and treatment groups averaged 424.0 ± 13.7 g and 421.8 ± 12.6 g, respectively (p = 0.908). Likewise, the milk production of sows from Days 3 to 10 and from Days 10 to 17 of lactation in the treatment group (7.34 ± 0.27 and 8.76 ± 0.43 kg/day, respectively) did not differ from that of the control group (7.85 ± 0.30 and 9.55 ± 0.47 kg/day, respectively, p > 0.05). Pre-weaning piglet mortality was slightly lower in the treatment group (13.4% vs. 17.3%, p = 0.085). Across groups, piglet mortality rates within 3, 7, and 21 days were 10.3%, 11.9%, and 15.4%, respectively. Piglets with a ≤200 g colostrum intake had a higher pre-weaning mortality compared to those with a higher intake (p < 0.05), except for the 201–300 g intake (p = 0.472). In conclusion, introducing dietary fiber to sows during the transition period reduced constipation and tended to decrease farrowing duration, especially in sows with large litters. Additionally, it lowered pre-weaning piglet mortality by 3.9% in the free-farrowing system. Nonetheless, providing sows with a 75 g/day dietary fiber supplement for only 7 days before farrowing was not enough to enhance colostrum and milk production, nor did it lead to an increase in piglet colostrum consumption. [ABSTRACT FROM AUTHOR]

The present study investigated impact of the interval between the last meal and the onset of farrowing on the duration of farrowing, stillbirth rates, and colostrum production in highly productive sows in a tropical climate. The study involved a total of 92 Danish Landrace x Yorkshire sows (herd A) and 114 French Landrace x Yorkshire sows (herd B). In herd B, a total of 61 sows had their blood samples collected within 1 hr after the onset of farrowing to evaluate their blood glucose levels. The interval between the last meal and the onset of farrowing averaged 5.9 ± 4.5 and 5.4 ± 4.1 hr in herds A and B, respectively. Neither the duration of farrowing nor the occurrence of stillborn piglets in both herds was affected by the time gap between the last meal and the onset of farrowing. At the onset of farrowing, the average blood glucose level in sows was 77.1 ± 19.3 mg/ dL, with a range of 27 to 115 mg/dL. There was a positive correlation observed between the blood glucose concentration and the colostrum yield of the sows (r=0.261, P=0.042). In conclusion, the time interval between the last meal and the onset of farrowing did not have any impact on the farrowing performance of sows. However, a higher concentration of blood glucose at the onset of farrowing was associated with an improvement in the colostrum yield of the sows. [ABSTRACT FROM AUTHOR]

This study analysed data from a commercial swine herd in Thailand equipped with a free‐farrowing housing system, comprising 17,196 piglets from 1318 litters, to explore the impact of sow and litter characteristics on the piglet birth weight and the incidence of stillbirth. The piglets were classified into four groups based on the total number of piglets born per litter (TB): ≤9 (n = 1434), 10–12 (n = 3232), 13–15 (n = 6537) and ≥16 (n = 5993). Sows were classified into four groups based on parity number: 1, 2–4, 5–7 and ≥8. The piglets were categorized into quartiles based on their birth order ranking: Q1 (n = 4786), Q2 (n = 4143), Q3 (n = 3808) and Q4 (n = 4456). Piglet birth weight was individually measured before colostrum ingestion. On average, TB, the number of live‐born piglets and the incidence of stillbirth were 13.1 ± 3.7, 11.5 ± 3.8 and 6.3%, respectively. Among these litters, 26.6% had TB numbers ≥16. The average piglet birth weight was 1.37 ± 0.36 kg, with 18.3% of piglets weighing ≤1.0 kg at birth. Piglet birth weight was influenced by birth order ranking, as Q4 piglets were found to be heavier than piglets born in Q1–Q3 (p <.001). Moreover, the percentage of piglets with a birth weight of ≤1.0 kg increased from 5.9% in litters with TB of ≤9–25.3% in litters with TB of ≥16 (p <.001). Additionally, primiparous sows had lower piglet birth weights compared to sows with parity numbers 2–4, 5–7 and ≥8 (p <.001). Piglets born in the fourth quartile (Q4) had a higher risk of stillbirth compared to those born in the first (Q1), second (Q2) and third (Q3) quartiles (12.5% vs. 2.2%, 4.1% and 6.6%, respectively, p <.001). The incidence of stillbirth in litters with TB ≥16 was also higher than that in litters with TB ≤9 and 10–12 (p <.05). Furthermore, sows with parity numbers ≥8 had a higher incidence of stillbirth (9.7%) compared to primiparous sows (4.0%, p <.001), sows with 2–4 parity (5.2%, p <.001) and sows with 5–7 parity (7.6%, p =.003). In summary, a high incidence of stillbirth was found in piglets born in the last quartile of litters, in litters with >16 piglets and for sows with parity numbers ≥8. Piglets born in the last quartile of litters were heavier than those born in the first to third quartiles. [ABSTRACT FROM AUTHOR]

Simple Summary: Semen possesses unique microbiota that are distinct from other microbial populations, such as those in the piglet gut and sow vagina. Environmental variations can result in alterations in the bacterial composition, which might not be detrimental but instead could be essential for sustaining optimal sperm functionality. The present study investigated the seminal microbiota in boars in relation to sperm quality. We found a negative linear relationship between the dominant bacterial orders, specifically potential probiotic bacteria (Lactobacillales) and harmful bacteria (Enterobacterales). Moreover, the abundance of potential probiotic functional bacteria was more frequently observed in high-quality ejaculates. Differences in the abundance of specific small subsets of microbes and their interactions revealed more precise effects on sperm quality than the overall seminal bacterial content (CFU/mL). The findings suggest that alterations in the seminal microbiome are significantly associated with the quality of boar semen, and strategies to increase the richness of functional candidates such as Lactobacillus spp. through herd management practices (e.g., seasonal changes, feeding, microbial exposure, antibiotics, and probiotics use) could create favorable reproductive potentials. The present study was carried out to determine the seminal microbiota of boars and their correlation with sperm quality. A total of 17 ejaculates were collected from 17 Duroc boars and were classified according to sperm quality into two groups: low-quality (n = 8) and high-quality (n = 9). Each ejaculate was subjected to (i) semen evaluation, (ii) bacterial culture and MALDI-TOF identification, and (iii) 16S rRNA gene sequencing and bioinformatic analyses. No difference in the total bacterial count, alpha diversity, and beta diversity between the high-quality group and the low-quality group was detected (p > 0.05). While Globicatella sanguinis was negatively correlated with sperm quality (p < 0.05), Delftia acidovorans was positively correlated with sperm quality (p < 0.05). Lactobacillales (25.2%; LB) and Enterobacterales (10.3%; EB) were the most dominant bacteria and negatively correlated: EB = 507.3 − 0.5 × LB, R2 = 0.24, p < 0.001. Moreover, the abundance of Escherichia-shigella was negatively correlated with LB (r = −0.754, p < 0.001) and positively correlated with Proteus (r = 0.533, p < 0.05). Alysiella was positively correlated with Lactobacillus (r = 0.485, p < 0.05), Prevotella (r = 0.622, p < 0.01), and Staphylococcus (r = 0.489, p < 0.05). In conclusion, seminal microbiota is significantly associated with boar semen qualities. The distributions of the most dominant bacterial genera, the differences in the abundance of small subset microbes, and their correlation appear to have far more impact than the overall seminal bacterial content (e.g., total bacterial count, alpha diversity, and beta diversity) on sperm quality. [ABSTRACT FROM AUTHOR]