LH peak and ovulation after two different estrus synchronization treatments in buffalo cows in the daylight-lengthening period

Clinical Modalities for Enhancing Reproductive Efficiency in Buffaloes: A Review and Practical Aspects for Veterinary Practitioners

This review aimed to bring a comprehensive analysis of key clinical strategies for enhancing reproductive efficiency in buffaloes, a species that exhibit low reproductive performance under conventional reproductive management compared to that exhibited by cattle. It considers key ART techniques including estrus synchronization for artificial insemination, and ovulation induction, highlighting their role in improving fertility and overall herd productivity. However, it also addresses common postpartum inflammatory and functional reproductive disorders, discussing their diagnosis and treatment protocols, stressing their impact on the overall reproductive outcome in buffalo farming.

Interferon-Tau in Maternal Peripheral Blood and Its Relationship with Progesterone and Pregnancy-Associated Glycoproteins in the Early Phases of Gestation in Water Buffalo

The aim of this study was to investigate the interferon tau (IFNt) concentration in the peripheral maternal blood during the early phase of pregnancy in buffalo cows and improve the knowledge on the physiological importance of circulating IFNt, evaluating the possible interaction with pregnancy-associated glycoproteins (PAGs) and progesterone (P4). Blood samples were taken from buffalo cows on day 0 (day of AI), 7, 14, 18, 28, and 40 post insemination for the IFNt, PAG, and P4 analysis and to determine the IFNt mRNA expression. The animals were categorized ex post into Pregnant, Non-pregnant and Embryo mortality groups. The interferon value was influenced by group (p = 0.003), being always higher in pregnant buffalo cows than in non-pregnant ones, while the embryo mortality group showed intermediate values between those for pregnant and non-pregnant animals. The mRNA expression of IFNt was not influenced by groups or any time points. The regression analysis that included IFNt as the independent variable showed that PAGs, from day 18 (p < 0.01), and P4, from day 28 (p < 0.05), were positively associated with IFNt values. The close associations among IFNt, PAGs and P4 demonstrate that all three molecules work together for fetal-placental well-being and pregnancy support. Unfortunately, the great individual variability in circulating IFNt makes this analysis unsuitable for early pregnancy diagnosis.

Peri-estrus activity and mounting behavior and its application to estrus detection in Hanwoo (Korea Native Cattle)

This study was conducted to investigate the change in activity and mounting behavior in Hanwoo (Korean Native Cattle) during the peri-estrus period and its application to estrus detection. A total of 20 Hanwoo cows were fitted with a neck-collar accelerometer device, which measured the location and acceleration of cow movements and recorded the number of instances of mounting behavior by the altitude data. The data were analyzed in three periods (24-, 6-, and 2-h periods). Blood samples were collected for 5 days after the prostaglandin F2α (PGF2α) injection, and the concentrations of estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone were determined by enzyme-linked immunosorbent assays. Activity and mounting behavior recorded over 2-h periods significantly increased as estrus approached and were more efficient at detecting estrus than over 24- and 6-h periods (p < 0.05). Endocrine patterns did not differ with the variation of individual cows during the peri-estrus period (p > 0.05). Activity was selected as the best predictor through stepwise discriminant analysis. However, activity alone is not enough to detect estrus. We suggest that a combination of activity and mounting behavior may improve estrus detection efficiency in Hanwoo. Further research is necessary to validate the findings on a larger sample size.

Interferon Tau (IFNt) and Interferon-Stimulated Genes (ISGs) Expression in Peripheral Blood Leukocytes and Correlation with Circulating Pregnancy-Associated Glycoproteins (PAGs) during Peri-Implantation and Early Pregnancy in Buffalo Cows

The objective of this study was to analyze interferon-stimulated genes (ISGs) and interferon tau (IFNt) gene expression in peripheral blood leukocytes during the peri-implantation period and until 40 days of pregnancy in buffalo cows. Relationships were also examined between the expression of ISGs and IFNt and pregnancy-associated glycoproteins (PAGs) peripheral plasma concentration. Buffalo cows were synchronized and artificially inseminated (d 0). Blood samples were collected on days 0, 18, 28 and 40 after artificial insemination (AI) for peripheral blood mononuclear cells (PBMCs) and polymorphonuclear leukocytes (PMNs) isolation and PAGs radioimmunoassay analysis. The study was carried out on 21 buffalo cows divided ex post into Pregnant (n = 12) and Non-pregnant (n = 9) groups. Steady state levels of OAS1, MX2, ISG15 and IFNt mRNA were measured by RT-qPCR and their estimated marginal means (p < 0.01 for all) were higher in pregnant than non-pregnant buffaloes, both in PBMCs and PMNs. In PBMCs, pairwise comparisons showed that OAS1 and MX2 expressions differed between pregnant and non-pregnant buffaloes on all the days of observation (p < 0.001), while significant differences in ISG15 and IFNt started from day 28 post-AI (p < 0.05). In PMNs, ISG15 expression differed between groups only at days 18 and 28 (p < 0.001), while comparisons were always significant for IFNt (p < 0.05). The expression of all genes, except ISG15 as determined in PMNs, was positively associated with PAGs plasma concentrations (p < 0.05). This work showed a significant increase in ISGs and IFNt expressions in PBMCs and PMNs in buffalo during the peri-implantation period and early pregnancy, and their correlation with PAGs plasma concentration.

Pregnancies following Protocols for Repetitive Synchronization of Ovulation in Primiparous Buffaloes in Different Seasons

Simple Summary

Artificial Insemination (AI) is mainly used after estrus synchronization in buffalo, and consecutive synchronization protocols are used to enhance reproductive efficiency. In this study, two different synchronization protocols have been used: Ovsynch vs. a P₄-administration, and their efficiency in primiparous animals has been evaluated in different seasons for up to four cycles of re-synchronization protocols. Results show that the pregnancy rate upon the initial AI tends to be higher in P₄ treated buffaloes, and that AI efficiency after re-synchronization through P₄ is higher than the Ovsynch protocol. In conclusion, synchronization treatments must be selected according to the season of the year. The results derived from this study could be useful for buffalo breeders who want to improve the reproductive efficiency in primiparous animals in commercially managed buffalo herds.

Abstract

Primiparous buffaloes were tested in two periods of the year characterized, by either low or high reproductive efficiency. They were subjected to two protocols for synchronization of ovulation: (i) Ovsynch (OV) and (ii) progesterone based (P₄) treatment. After calving, the animals underwent a series of four cycles of re-synchronization protocols. The season did not affect pregnancy rates when the results of the two treatments were pooled together with regard to the first synchronization protocol, followed by AI. Pregnancy rates were similar during the low breeding season (50.3% vs. 57.4% in OV and P₄, respectively), but different during the high breeding season (50.4% vs. 67.7% in OV and P₄, respectively; p = 0.000). Logistic regression confirmed a significant effect of treatment and season interaction on pregnancy (p = 0.003). Following re-synchronization, a treatment by season interaction was detected during the low breeding season (odds ratio = 2.233), in favor of P₄. Finally, a survival analysis showed a better response of animals subjected to P₄ treatment from the second AI onward. In conclusion, the pooled data of pregnancy rates from both treatments between seasons are not different following AIs. Better results, though, were obtained from the implementation of P₄ treatment, and are recorded in a season-fashioned mode when the comparison is made following first or cumulative AIs.

Use of GnRH Treatment Based on Pregnancy-Associated Glyco-Proteins (PAGs) Levels as a Strategy for the Maintenance of Pregnancy in Buffalo Cows: A Field Study

The aim of the study was to evaluate the effects of GnRH administrated at day 35 after artificial insemination (AI) on the reproductive performance of buffalo cows. In ten buffalo farms in the period January−February, 481 buffalo cows were subjected to estrus synchronization protocol and fixed-time artificial insemination (Ovsynch−TAI program). Radioimmunoassays (RIA) for pregnancy-associated glycoproteins (PAGs) were used to detect pregnancy at day 28 after AI (cut-off value: ≥1 ng/mL). Among pregnant subjects, those with PAG values between 1 and 2.5 ng/mL were considered at risk of embryonic mortality (EM) and were assigned into two groups: treated (T; n = 57) control (C; n = 57). Treated buffaloes received 0.01 mg of buserelin acetate intramuscularly on day 35 after AI, whereas control buffaloes received no treatment. The pregnancy diagnosis was confirmed at day 60 through PAGs level and rectal palpation. The treatment with GnRH had a significant effect (p < 0.001) in reducing EM. Between days 28 and 60 after AI, the animals that experienced EM were only 2/57 in the T group, while were 13/57 in the C group. Moreover, GnRH treatment produced a significant increase (p < 0.001) in the PAG concentration between day 28 and day 60. Administration of GnRH at day 35 after AI in animals considered at risk of low embryo survival based on PAG levels allowed a reduction in pregnancy losses and improved the pregnancy rate during low-breeding season in buffalo.

Using Pregnancy-Associated Glycoproteins (PAGs) to Improve Reproductive Management: From Dairy Cows to Other Dairy Livestock

Simple Summary

Pregnancy loss is a major cause of infertility in dairy animals, particularly in cattle, which affects the productivity and profitability of farms. Detecting these unsuccessful pregnancies could offer farmers the opportunity to reduce the economic damage caused by pregnancy loss. The determination of proteins secreted by the placenta and related to the presence of a viable conceptus called pregnancy-associated glycoproteins (PAGs) represents a diagnostic tool to identify pregnant or non-pregnant animals and to predict early pregnancy failures. This review describes the state of the art related to PAGs’ function, pregnancy profile, and use in reproductive management in bovine and other dairy livestock.

Abstract

Pregnancy success represents a major issue for the economic income of cattle breeders. Early detection of pregnant and non-pregnant animals, as well as the prediction of early pregnancy failure, can influence farm management decisions. Several diagnostic tools for pregnancy are currently available. Among these, pregnancy-associated glycoproteins (PAGs) have been shown to be useful for identifying the presence of vital embryos and for pregnancy follow-up monitoring. This review presents an overview of the PAGs’ functions, their pregnancy trends, and their use as a tool to improve reproductive management in bovine and other dairy livestock, such as small ruminants and buffalos.

Effect of Different Synchronization Regimens on Reproductive Variables of Crossbred (Swamp × Riverine) Nulliparous and Multiparous Buffaloes during Peak and Low Breeding Seasons

The present study was conducted to examine the effect of conventional the Ovsynch protocol (OVS) and a modified Ovsynch synchronization (GPGMH) protocol on the follicular dynamics, estrus, ovulation, and pregnancy in nulliparous and multiparous crossbred (swamp × riverine) buffaloes during different seasons. GPGMH or OVS protocols were used to synchronize nulliparous (n = 128; GPGMH = 94, OVS = 34) and multiparous (n = 154; GPGMH = 122, OVS = 32) buffaloes during the peak (n = 186; GPGMH = 143, OVS = 43) and low breeding (n = 96; GPGMH = 73, OVS = 23) seasons. Buffaloes were monitored for follicular dynamics, estrus response, ovulation, and pregnancy rates. The results showed that protocol, parity, and season had significant effects on estrus, ovulation, and pregnancy variables, and interactions among parity and protocol, season and protocol, and season and parity were observed for few of reproductive indices in the crossbred buffaloes. There were no significant (p > 0.05) interaction for protocol, parity and season. In multiparous buffaloes, the application of the GPGMH protocol significantly (p < 0.05) increased the interaction to the interval to estrus onset after the second GnRH, estrus response, ovulation rate, and pregnancy rate, and lowered (p < 0.05) the silent estrus when compared with the conventional OVS protocol. During the peak breeding season, the application of the GPGMH protocol significantly (p < 0.05) improved the interaction to the estrus response, ovulation rate, and pregnancy rate, while it lowered (p < 0.05) the silent estrus incidence when compared to the conventional OVS protocol. In conclusion, the GPGMH protocol, in comparison to the OVS protocol, improves the follicular dynamics, estrus response, ovulation, and pregnancy rates in crossbred multiparous buffaloes during the peak breeding seasons.

Approaches to Identify Pregnancy Failure in Buffalo Cows

Simple Summary

Embryonic mortality and pregnancy failures still represent a major issue in domestic livestock production, particularly in dairy cattle. Despite the presence of extensive work in this research area, there is still no effective, accurate and practical method able to determine timing and viability of embryo specifically during early gestation. Indeed, technologies and techniques for predicting pregnancy success must continue to be developed. The aim of this work was to find the best strategy to diagnose pregnancy failures in buffalo cows in order to improve farm reproductive management. Among the methods compared in this study (ultrasonography, progesterone, PAGs), pregnancy-associated glycoproteins (PAGs) seem to be the best marker for predicting embryonic mortality between 25 and 40 days of gestation to be utilized as a diagnostic tool to improve reproductive management in buffalo farms.

Abstract

The aim of this work was to find the best strategy to diagnose pregnancy failures in buffalo. A total of 109 animals belonging to a buffalo herd subjected to a synchronization and artificial insemination (AI) program were enrolled in this study. Blood samples were collected at days 0, 14, 25, 28 and 40 after AI for the determination of progesterone (P4) and pregnancy-associated glycoproteins (PAGs) by the radioimmunoassay (RIA) method. Transrectal ultrasonography was performed on day 25, 28 and 40 after AI to monitor pregnancy. The animals included in the data analysis were assigned ex post in pregnant (n = 50) and mortality (n = 12) groups. By ultrasonography, the predictive sign of mortality was the heartbeat. At day 25, the PAGs concentration was significant in predicting embryonic mortality with respect to ultrasonography and P4, at the cut-off of 1.1 ng/mL. At day 28, either PAGs, at a cut-off of 2.2 ng/mL, or ultrasonography, with no detection of heartbeat, were highly predictive of embryonic mortality. PAGs were the best marker (p < 0.05) for predicting embryonic mortality between 25 and 40 days of gestation in buffalo. Its utilization as a diagnostic tool can influence management decisions in order to improve farm reproductive management.

Salivary luteinizing hormone: An open window to detect oestrous period in buffalo

Silent oestrus is an unsurmountable problem in the management of buffalo reproduction. In addressing this issue, we have earlier reported variation in the levels of urinary luteinizing hormone (LH) through the different phases of oestrous cycle with an extended window during the mid-oestrous phase. Based on this report, the present study is designed to assess the salivary LH levels in buffalo during the different phases of oestrous cycle. Bovine LH ELISA kit was used to determine the level of salivary LH. We observed a notable variation in salivary LH levels during the different phases of oestrous cycle. The maximum LH level, 39.07 mIU/ml, observed during oestrus, which was significantly (p < .05) higher than other consecutive phases. Altogether, the results showed a significant (p < .05) fold variation during oestrus compared with other phases. Therefore, the study convincingly shows that salivary LH has the potential of application in development of a modality for non-invasive oestrous detection in buffalo.

Serum microRNAs in buffalo cows: Potential biomarkers of pregnancy

MiRNAs (microRNA) constitute a large family of single-stranded, non-coding small RNAs. Although the functions and target genes of most miRNAs are still unknown, it has been well established that they are involved in embryogenesis, organogenesis and neonatal birth. In recent decades, interest in buffalo breeding has largely increased worldwide thus focusing the attention on this species as a dairy purpose animal. Problems related to long calving interval, late puberty and seasonal anestrus hamper reproductive efficiency in this species. Early pregnancy diagnosis is important to shorten the calving interval and increase lifetime production on dairy animals. MicroRNAs have recently emerged as key molecules in fertilization of several species even though in buffalo, few previous studies have investigated miRNAs. The aim of this research was to identify the best miRNA reference in serum among miR-191, miR-25-3p, SNORD44, and SNORD48. Consequently, assess the expression levels of miR-103, miR-200b, miR-301a, miR-423-5p, miR-375, miR-451 and miR-452 involved in buffalo progesterone-maturation oocyte and pregnancy. Interestingly, we found that all the miRNAs analyzed at 40days after artificial insemination were differentially expressed among pregnant and non-pregnant buffalo. Our research may be a first step for gain further insight in the biological function of circulating miRNAs in this species.

Protein and mRNA expression of follicle-stimulating hormone receptor and luteinizing hormone receptor during the oestrus in the yak (Bos grunniens)

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) have a central role in follicle growth, maturation and oestrus, but no clear pathway in the seasonal oestrus of yak (Bos grunniens) has been found. To better understand the role of FSH and LH in seasonal oestrus in the yak, six yaks were slaughtered while in oestrus, and the pineal gland, hypothalamus, pituitary gland, and gonads were collected. Using real-time PCR and immunohistochemical assays, we determined the mRNA and protein expression of the FSH and LH receptors (FSHR and LHR) in these organs. The analysis showed that the FSHR mRNA expression level was higher in the pituitary gland tissue compared with LHR (p < .01) during oestrus. By contrast, there was low expression of FSHR and LHR mRNA in the pineal gland and hypothalamus. FSHR mRNA expression was higher than that of LHR (p < .05) in the ovary, whereas LHR mRNA expression was higher than that of FSHR (p < .01) in the uterus. FSHR and LHR proteins were located in the pinealocyte, synaptic ribbon and synaptic spherules of the pineal gland and that FSH and LH interact via nerve fibres. In the hypothalamus, FSHR and LHR proteins were located in the magnocellular neurons and parvocellular neurons. FSHR and LHR proteins were localized in acidophilic cells and basophilic cells in the pituitary gland, and in surface epithelium, stromal cell and gland epithelium in the uterus. In the ovary, FSHR and LHR protein were present in the ovarian follicle. Thus, we concluded that FSHR and LHR are located in the pineal gland, hypothalamus, pituitary and gonad during oestrus in the yak. However, FSHR was mainly expressed in the pituitary gland and ovaries, whereas LHR was mainly expressed in the pituitary gland and uterus.

Using real-time PCR to identify pregnancy-associated glycoprotein 2 (PAG-2) in water buffalo (Bubalus bubalis) blood in early pregnancy

This study investigates for the first time mRNA pregnancy-associated glycoprotein 2 (PAG-2) expression in blood cells during early pregnancy in water buffalo. The PAGs constitute a large family of glycoproteins expressed in the outer epithelial layer of the placenta in eutherian species. All PAGs are not concomitantly expressed throughout pregnancy; some of them are expressed in the earlier phases, whereas others appear later and are expressed over a shorter period. Twenty-one lactating buffaloes were analyzed-17 females were synchronized with PRID and artificially inseminated (AI), whereas four females were synchronized but not inseminated (control group). Blood was collected at Days 0, 18, 28, 40, and 75 from AI (AI = Day 0). Expression of PAG-2 mRNA in blood samples was measured with real-time polymerase chain reaction. Pregnancy diagnosis was performed on Day 28 (D28) and Day 40 (D40) after AI by ultrasonography (US) and by PAG-1 RIA method. The females diagnosed pregnant at D28 and confirmed pregnant at D40 were defined as D28(+)D40(+) group; the females diagnosed pregnant at D28 but not confirmed pregnant at D40 were defined as D28(+)D40(-) group; and the females that were diagnosed as nonpregnant on either days were defined as D28(-)D40(-) group. PAG-2 mRNA at Day 0 was not observed in any groups. The D28(+)D40(+) group showed the highest expression, starting on Day 18 and increasing progressively up to Day 75. PAG-2 mRNA was also expressed on Day 18 in both D28(+)D40(-) and D28(-)D40(-) groups, but their levels were lower than those of D28(+)D40(+) group and almost constant over time. PAG-2 mRNA was never detected in the control group. The significant difference in the expression of PAG-2 mRNA between the D28(+)D40(+) group and the D28(-)D40(-) group, starting from Day 18, suggests that these animals might have conceived, but have experienced early embryonic loss; therefore, the PAG-2 mRNA was still present in blood circulation although at lower levels, as found in the D28(+)D40(-) group. In conclusion, this study shows that PAG-2 mRNA can be detected in peripheral maternal blood cells earlier than circulating PAG-1 molecules and could be useful for studies on early pregnancy and embryonic mortality.

The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1×10(10) (T1, n=41), 1×10(9) (T2, n=37), 1×10(8) (T3, n=37) or 0 (C, n=43) CFU/ml bacteria delivered inhibin vaccine in 10ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5mg PGF2α on day 30 and 200μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P<0.01). The number and diameter of large follicles (≥10mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P<0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P<0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.