Efficiency Of Mares Research Articles

Platelet-Rich Plasma Proteome of Mares Susceptible to Persistent-Breeding-Induced Endometritis Differs from Resistant Mares.

Persistent-breeding-induced endometritis (PBIE) is the leading cause of subfertility and poor reproductive efficiency in mares. Platelet-rich plasma (PRP) treatment has been shown to mitigate PBIE, reduce uterine infections, and improve fertility in mares. However, the proteome of PRP in mares, particularly those susceptible to PBIE, remains unknown. This study aimed to fill this knowledge gap by comparing the most abundant proteins present in PRP prepared from mares with histories of being susceptible or resistant to PBIE. The study involved twelve light-breed mares: seven susceptible and five resistant to PBIE. A complete blood count and physical examination were performed on each mare before blood drawing to ensure good health. The PRP was prepared following collection in a blood transfusion bag and double centrifugation. Platelet counts in the PRP were compared across the groups. The PRP was cryopreserved in liquid nitrogen until proteomics could be completed. Physical parameters and complete blood cell counts were within normal ranges. The platelet counts for resistant (561 ± 152 × 103) and susceptible mares (768 ± 395 × 103) differed (p < 0.05). One hundred and five proteins were detected in all mares, and four proteins were more abundant in resistant mares (p < 0.05). The proteins were apolipoprotein C-II, serpin family G member 1, protection of telomeres protein 1, and non-specific serine/threonine protein kinase. All these proteins are linked to the immune response. These results suggest that PRP prepared from mares resistant to PBIE may be more beneficial in mitigating PBIE in mares, offering a promising avenue for improving equine reproductive health. However, this remains to be determined with in vivo studies.

Pregnancy rates according to follicle diameter and uterus edema in different age groups in two consecutive ovulations in Arabian mares

The study aimed to evaluate the pregnancy rates of mares in different age groups based on follicle diameter and uterine edema during two consecutive ovulations in three breeding seasons. Thirty Arabian mares were divided into two groups: below and equal to 10 years (Group A=54) and above 10 years old (Group B=36). Throughout the breeding season, the diameters of ovulatory follicles and uterine edema were recorded. After the first ovulation, when the follicle diameters of all mares in both Group A and Group B were analyzed independently of age, and compared between pregnant and non-pregnant mares, no differences were found (P&gt;0.05). The differences between the agerelated groups were insignificant (P&gt;0.05). Follicle diameters between pregnant and non-pregnant mares at the second ovulation were significantly different (P0.05). Differences between uterine edema values determined in mares that were pregnant and nonpregnant in two consecutive ovulations were found to be insignificant in terms of pregnancy (P&gt;0.05). As a result, although preovulatory diameter is not a reliable marker for pregnancy detection, it remains an important parameter for determining ovulation and artificial insemination timing. Uterine edema is only useful for determining the timing of insemination and is not associated with pregnancy. Moreover, since similar pregnancy rates were observed among different age groups, age alone is not a sufficient parameter for assessing reproductive efficiency in mares.

Effect of age and of reproductive status on reproductive indices in horse mares carrying mule pregnancies

Mules (Equus mulus) are interspecific hybrids derived from crossing horse (Equus caballus) mares with jackasses (Equus asinus). In Italy, the production of mules is very important for the special environmental areas, where they are used as working animals, instead of the forbidden agricultural machines. Although many horse mares carry mule pregnancy successfully at term, low fertility of mares used for producing mules was reported, but limited data about reproductive efficiency in mares carrying mule pregnancy, especially when age and reproductive status are concerned, are available. Therefore, the present study aimed to assess the effect of age and of reproductive status on some reproductive indices of horse mares carrying mule pregnancy, in the final purpose to better clarify factors affecting reproductive performances in the valuable production of mules as working animals under special environmental areas in Italy.The study, performed on 96 draft mares inseminated with Martina Franca donkey semen, showed a satisfactory 89.6% 14 days PO pregnancy rate, lower pregnancy losses (19.8%) than those previously reported for mule pregnancies, leading to satisfactory foaling rates (71.9%), similar to those reported for intraspecific horse pregnancies. A clear, significant detrimental effect of mare's age on pregnancy losses, foaling rate, and on number of estrous cycles needed to achieve pregnancy, was found. Reproductive status also affected the reproductive indices, with significantly higher pregnancy losses and lower foaling rate in barren mares, reopening the question about the possible lower reproduction efficiency in horse mares carrying mule pregnancy. The present study results, although mostly descriptive, add useful information about some factors affecting reproductive performances in the valuable production of mules as working animals under special environmental areas in Italy.

Effect of different types of artificial insemination and semen dose on reproductive efficiency in mares

Effect of different types of artificial insemination and semen dose on reproductive efficiency in mares

332 Effect of dietary l-arginine on blood flow dynamics, gestation length, and placental efficiency of mares

332 Effect of dietary l-arginine on blood flow dynamics, gestation length, and placental efficiency of mares

Escherichia coli Lipopolysaccharide-Induced Immunomodulation Along With Oxytocin Administration After Mating as a Treatment Protocol for Persistent Endometritis in Mares

Endometritis is accepted as a major hindrance to achieve optimal reproductive efficiency in mares. The objective of the present study was to evaluate the therapeutic efficacy of combined therapy of immunomodulator and ecbolic as an alternative stand-alone therapy for mares with persistent endometritis. On the basis of history, culture, endometrial cytology, and per rectal and/or ultrasonographic genital examinations, 76 subfertile mares were selected and assigned to three age groups and four treatment (G-1, 2, 3) and control (G-4) groups. At estrus, all the mares were bred once naturally. Thereafter, the mares of G-1 (n = 28) were aseptically treated at 6-hours after natural service with intrauterine infusion (in 50 mL normal saline solution) of 100 μg of Escherichia coli lipopolysaccharide (LPS). Additionally, these mares received two injections of 20 IU of oxytocin (IV) at 12 and 24-hours after infusion. Mares in group G-2 (n = 11) were treated with LPS as mares of G-1, whereas mares in G-3 (n = 12) received oxytocin injections only. The mares of G-4 (n = 23) did not receive any treatment. Pregnancy rates at day 21 and foaling rates were higher ( P < .001) in group G-1 than in G-4. In G-1, higher percentage of mares at ages 6–10 years conceived and foaled than mares aged ≥16 years. On re-swabbing of mares that remained nonpregnant, the majority of G-1 and G-2 mares demonstrated sterile cultures and negative cytology, whereas uterine inflammation persisted in mares of G-3 and G-4. In conclusion, the combined therapy was effective for the elimination of persistent endometritis and improved reproductive performance of subfertile mares.

A clinical view of mare reproductive physiology

Summary An understanding of clinically relevant aspects of equine reproductive physiology is helpful to the stud farm practitioner. Anestrus and transition can delay the desired onset of the breeding season and reduce the number of opportunities to establish pregnancy during the season. Although alteration of the photoperiod has long been accepted as the best way to advance the breeding season, recent research may provide additional assistance for hastening the onset of cyclicity. During the breeding season, knowing the pattern of ovulation in mares, both in general and for a particular mare, can be very beneficial in timing insemination for optimum conception rates. Likewise, appreciating the effects of luteolytic agents on aspects of reproductive physiology other than regression of the corpus luteum, such as on follicular development, ovulation, and development of hemorrhagic anovulatory follicles, can assist the clinician in improving breeding efficiency in mares.

181 CHANGES IN THE BODY CONDITION STATUS OF DONOR MARES THROUGHOUT THE BREEDING SEASON AND THEIR RELATIONSHIP WITH REPRODUCTION TRAITS

The objective was to investigate the relationship between changes in body condition on reproductive traits of donor mares in an embryo collection program. Fifty-six non-pregnant mares, 3 to 18 years old, were studied from August 2008 through April 2009. Body condition score (BC; 1-9 scale, thin to obese) was estimated monthly. Body weight and tail and rib s.c. fat depths (SF) were measured monthly. SF was determined by ultrasound. Dominant follicle diameter (DF) was measured daily during the follicular phase. Mares were artificially inseminated and embryo transfers were conducted 6 d after ovulation. Analyses were performed with SAS® (SAS Institute Inc., Cary, NC, USA). Age classes were as follows: age 1, 3 to 6.9 (n = 17); age 2, 7 to 12.9 (n = 25), and age 3, ≥13 years (n = 14). Months in experiment were T1 to T6. BC classes were as follows: B1, &lt;6.5; B2, 6.5 to 6.9; B3, 7.0 to 7.5; and B4, &gt;7.5. Embryo recovery rate was compared by chi square. Effects of month and age on BC, weight, and SF were analyzed by a mixed model. Age, BC, and month fixed effects on DF diameter were analyzed by ANOVA with mare within class as the error term. Means were compared by contrasts. BC was higher (P = 0.02) in older mares (6.78 ± 0.2 and 6.93 ± 0.2 in age 1 and age 2 v. 7.25 ± 0.2 in age 3) and increased (P = 0.009) with time (from 6.79 ± 0.20 to 7.42 ± 0.26 for T1 to T6, respectively). Weight (kg) was not associated with age but increased (P = 0.03) throughout the experiment. Tail fat increased with age (P = 0.04) and decreased with increasing months on experiment (P = 0.02). DF diameter increased daily through the follicular phase (P &lt; 0.0001) and was smaller (P &lt; 0.05) in mares with lower body condition (33.80 ± 0.31 in BC1 v. 34.17 ± 0.31 mm in BC4). DF diameter decreased (P &lt; 0.01) with month on study. Embryo recovery rate was not affected by age or BC but was lower (P = 0.003) in mares that ovulated follicles smaller than 40 mm compared to mares ovulating follicles greater than 40 mm. BC above 6.5 was associated with higher embryo recovery rate, which was, in turn, correlated positively with DF diameter. Thus, our results support the use of BC scoring to predict performance in equine embryo transfer programs. Body condition scoring was not a good indicator of SF under the current experimental conditions because SF decreased during the breeding season. BC scoring may indicate lean tissue gain, which may be a better indicator of reproductive efficiency in mares. FAPEMIG, CAPES, Haras El Far.

Markers of the uterine innate immune response of the mare

Reproductive efficiency in mares is low and persistent mating-induced endometritis (PMIE) is an important cause of subfertility. Mating-induced endometritis (MIE) an obligate precursor to PMIE, is a ubiquitous, transient inflammatory response to the presence of sperm, seminal components and pathogens. However, the specific inflammatory pathways that derive from MIE and that may also be precursors to PMIE are not clear. The ability to identify and measure robust, repeatable markers of inflammation integral to MIE may be key to understanding the progression to PMIE. The aim of the study was to (i) refine a protocol for inducing MIE and in doing so test a range of cellular and molecular parameters as valid markers of MIE to facilitate future studies of mares susceptible to PMIE (ii) concurrently identify those parameters with potential as inflammatory indicators during MIE to inform and enhance early treatment regimens in practice. Mating-induced endometritis was induced in pony mares using a stringent protocol; mares were treated intrauterine with frozen/thawed semen ( n = 5; FTS) or frozen/thawed extender ( n = 6: FTEx). The parameters tested were measured before treatment were compared to samples collected at strategic time points after treatment: uterine cytology using cytological (at 8, 16, 24, 48 and 72 h after treatment) or histological analysis (at 24 and 72 h); uterine bacteriology (at 24 and 72 h); secretion of prostaglandin F 2α (PGF 2α; at 8, 16, 24, 48 and 72 h); peripheral concentrations of serum amyloid A (SAA; at 24 h); endometrial mRNA gene expression, focussing upon IL8 and TLR4, as examples of genes pertinent to inflammation (at 24 h). Uterine neutrophil cell numbers in both treatment groups increased at 8 ( P < 0.001), 16 ( P < 0.01) and 24 ( P < 0.01) h after insemination, indicative of MIE and distinguished between different treatments because neutrophil numbers were greater from FTS mares than FTEx mares 8 h after challenge. Uterine neutrophil cell numbers, assessed by histology, increased ( P < 0.001) 24 and 72 h after treatment. Prostaglandin F 2α concentrations increased ( P < 0.05) 16 h after treatments, while SAA concentrations and bacterial growth scores were not significantly different after treatment. Endometrium from pony mares expressed mRNA for IL8 and TLR4 but expression was not altered after insemination. The protocol induced MIE, as confirmed by uterine cytology and maybe used hereafter as a repeatable and robust method for studying immune mechanisms that underlie MIE and so may aid the understanding of progression to persistent inflammation. It can be concluded that of the range of parameters tested, neutrophil cell numbers by cytological analysis and PGF 2α were regarded as the most accurate markers of inflammation during MIE and important for use in practice.

Induction of Estrus and Promotion of Fertility by Prostaglandin F2.ALPHA. Administrtion in Mares.

To reduce the intervals from Parturition to conception in normal multiparous mares and to promote the fertility in mares with reproductive failures, 13 mares, a total of 17 cases, were intramuscularly injected with prostaglandin F2α (PG) in the luteal phase. Ten mares came into estrue after the first injection of 5 mg of PG, whereas 3 mares required two or three PG treatments to induce estrus. Estrus was induced 5-8 days after PG treatment in 10 out of 14 cases that showed signs of estrus. The duration of estrus was 3.9 days on the average and 11 out of 17 cases ovulated 8-12 days after PG treatment. The number of matings was 1-5 times during the induced estrus and 11 mares conceived. A “star-like layering of the folds” in the uterine cavity appeared 2-6 days after PG treatment, and then disappeared 1-2 days before ovulation on ultrasonic monitoring. The plasma levels of progesterone (P) rapidly decreased following PG treatment, whereas the plasma levels of inhibin (INH) and estradiol-17β (E2) increased after PG treatment. The plasma concentrations of LH gradually increased following PG treatment and typical prolonged LH surges were observed during the periovulatory period. In contrast, the plasma concentrations of FSH decreased after PG treatment, followed by an increase after ovulation. There was an inverse relationship between the plasma concentrations of FSH and INH. The results of the present study clearly demonstrated that treatment with PG is a useful method for reducing the intervals from parturition to conception in multiparous mares, and for improving reproductive efficiency in mares with reproductive failure.

Relationships of age to uterine function and reproductive efficiency in mares

The uterine function and reproductive efficiency of 31 nonlactating pony mares were compared for two age groups: young (5 to 7 years, n=9) and old (≥15 years, n=22). For pregnant mares, differences between age groups were not significant for the diameter of the largest follicle, cross-sectional area of the corpus luteum, growth profile of the embryonic vesicle or embryo mobility characteristics. Uterine contractility scores were lower (P<0.05), day of fixation of the embryonic vesicle was later (P<0.05), and uterine tone tended (P<0.10) to be lower in the old than the young mares. Endometrial biopsies in old mares had more (P<0.05) inflammatory cell infiltrations, more (P<0.05) fibrotic changes, and less dense (P<0.05) endometrial glands than in young mares. Ultrasonically detected intrauterine fluid collections were more extensive (P<0.05) in the old than the young mares. The pregnancy rate on Day 12 (Day 0=ovulation) was lower (P<0.05) and embryo-loss rate (Days 12 to 39) was greater (P<0.05) in old (32 and 62%, respectively) than in young (100 and 11%, respectively) mares. The results confirmed previous reports that old age was associated with increased endometrial inflammation, reduced pregnancy rate and increased embryo-loss rate. The results also indicated that uterine contractility and uterine tone were reduced and the fixation of the embryonic vesicle occurred later in old than in young mares.

Effects of repeated hCG injections on reproductive efficiency in mares

Thirty reproductively sound mares were divided into treatment and control groups. In the treatment group, consisting of 14 mares, 2500 I.U. of human chorionic gonadotropin (hCG) was administered intravenously during estrus, in the presence of a 35 mm follicle over five successive cycles in 1987, and at least two cycles in 1988. Beginning with the second cycle of treatment in 1988, these mares were bred to a fertile stallion. The control group, consisting of 16 mares, was followed for two to five cycles in either the 1987 or 1988 season and six of these mares were bred to fertile stallions. Throughout the study period, blood was collected from the mares in the treatment group for analysis of anti-hCG antibodies and cross reactivity of the antibody to purified equine lutenizing hormone (eLH) and equine chorionic gonadotropin (eCG). In 1987, after the first three injections of hCG, mean duration of estrus in treated mares tended to be shorter than in control mares (P<.10). After all five hCG injections in 1987, mean ovulation time for treated mares was shorter than in control mares (P<0.01). However, after two to five hCG injections in 1987, seven treated mares (50%) had some individual ovulation times that did not differ from the control mares. Initially, following the first three injections of hCG in 1988, mean duration of estrus tended to be shorter (P<0.1) in treated mares compared to control mares. A reduction in mean ovulation time was observed after the first two hCG injections of 1988 (P<0.01). However, after one to four hCG injections in 1988, eight treated mares (57.1%) had some individual ovulation times that did not differ from controls. In 1987, all 14 treated mares developed significant levels of antibodies to hCG after one to four injections, and again in 1988, were positive for anti-hCG antibodies after one to three injections. However, no correlation was observed between magnitude of the immune response and duration of ovulation time or pregnancy rate. In cross reactivity studies, no significant binding of plasma anti-hCG antibodies to either eLH or eCG was observed in vitro. Overall, pregnancy and foaling rates of treated (85.7%) and control mares (83.3%) did not differ. Additionally, no difference was observed in number of inseminations per estrus between treated and control mares. In this study, with successive injections of hCG, the expected shortened time to ovulation was not elicited consistently in all mares. However, mares continued to ovulate, conceive and foal in the presence of significant levels of anti-hCG antibodies.