Mycobacterium branderi Infection in a Horse with Granulomatous Mesenteric Lymphadenitis.

Although relatively uncommon in horses, infections caused by Mycobacterium spp. may affect the gastrointestinal tract. Mycobacterium branderi is a non-tuberculous Mycobacterium (NTM) that causes respiratory infections in man. Non-tuberculous mycobacteria may also affect horses; however, infection by M. branderi has not yet been reported in this species. This report describes the clinical, pathological, microbiological and molecular findings of M. branderi infection in a horse, causing granulomatous mesenteric lymphadenitis. A 17-year-old Thoroughbred stallion had a 3-month history of chronic diarrhoea, cachexia and ventral and cervical oedema. Necropsy examination revealed severe mesenteric lymphadenomegaly, together with mesenteric lymphangiectasia and diffuse small intestinal mucosal thickening. Microscopically, the mesenteric lymph node had diffuse granulomatous inflammatory infiltration, replacing most of the nodal parenchyma, with multiple acid-fast bacilli within the cytoplasm of macrophages. There was also diffuse lymphangiectasia. Fresh samples of mesenteric lymph nodes yielded no bacterial growth; however, nested polymerase chain reaction products obtained from the mesenteric lymph node samples were consistent with M. branderi. This infection should be included as a differential diagnosis in cases of chronic diarrhoea in horses, especially when granulomatous enteritis and lymphadenitis are also observed.

Ultrastructural and histological characteristics of the equine endometrium at day 5 post ovulation.

Rapid endometrial adaptations occur with the embryo entering the uterus to create a receptive uterine environment, which is essential for the conceptus' development. The aim of this study was to demonstrate ultrastructural and histological changes of the endometrium at day 5 after ovulation in cyclic and inseminated mares. Mares were daily examined by transrectal palpation and ultrasonographic examination of the reproductive tract until ovulation was detected. In the first cycle, endometrial biopsies from 10 cyclic mares (Cyclic group) were collected on day 5 post-ovulation. In the second cycle, the same mares were inseminated with fresh semen from a fertile stallion (Inseminated group). Intrauterine biopsies were collected on day 5 post-ovulation, and according to sampling moment, inseminated mares were subdivided into two subgroups, those sampled at day 5-5.5 (n = 5) and those sampled at day 5.5-6 (n = 5). Biopsy samples were analyzed through scanning electron microscopy and light microscopy. Inseminated group presented an increase in glandular diameter, decrease in ciliated cell population, and an increase in lymphocyte population, compared to Cyclic group. No differences were observed between both experimental groups in number of micro-ciliated polygonal cells, percentage of flat or protruded cells in the epithelium, amount of secretion over the epithelium, glandular density, glandular luminal diameter, height of the glandular epithelium, amount of intraglandular secretion, blood vessel diameter and number of eosinophils and neutrophils. No differences in any of the variables were detected between subgroups from inseminated mares. These facts lead to the hypothesis that there is some sort of signaling to prepare and adapt the uterus to maintain pregnancy even before embryo arrival. There is also evidence to support an alternative hypothesis suggesting that all of the above mentioned are inflammatory events, resulting from a previous inflammation due to residual seminal effects. The results here presented lead to the conclusion that significant ultrastructural and histological changes of the endometrium occur on day 5 post ovulation in inseminated mares.

Proteomic profile of histotroph during early embryo development in mares.

There is a complex cascade involving proteins during early embryo development and maternal recognition, which is very important for maintenance of a conceptus. The aim of this study was to compare proteomic profile of uterine fluid after ovulation in pregnant and cyclic mares. In the first cycle, samples of uterine fluid of 30 cyclic mares were collected on days 7 (n = 10), 10 (n = 10) and 13 (n = 10) post ovulation and constituted the Cyclic group. In the second cycle, the same mares were bred to a fertile stallion. At days 7, 10 and 13 uterine fluid samples were collected. Immediately after sample collection, the mare's uteri were flushed, and those with an embryo recovered were assigned to the Pregnant group. Of the 30 mares flushed embryos were recovered from 6 mares on day 7, 6 on day 10 and 6 on day 13. Samples from the mares without embryo recovery were excluded from both groups. The uterine fluid samples were processed by two-dimensional electrophoresis technique followed by matrix assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry for the identification of relevant protein spots. From a total of 677 detected spots 19 were identified, 13 more abundant in Pregnant group and 6 in Cyclic group. In summary, pregnant and cyclic mares showed proteins with different abundance. Identified proteins were related to the transport of lipids through the embryo capsule, uterine motility, ATP generation, maternal immunological tolerance, cell proliferation, differentiation, metabolism and angiogenesis. Changes in the proteomic profile of uterine fluid during early embryo development in mares were related with the conceptus presence, suggesting that these alterations may be important for conceptus development and maternal recognition of pregnancy.

Ultrastructural and histological characteristics of the endometrium during early embryo development in mares.

The aim of this study was to evaluate ultrastructural and histological changes in the endometrium on days 7, 10 and 13 post-ovulation in pregnant and cyclic mares. Mares were routinely examined by transrectal palpation and ultrasonographic examination of the reproductive tract until estrus was detected. In the first cycle, endometrial biopsies from 30 cyclic mares (Cyclic group) were collected on days 7, 10 and 13 post-ovulation. In the second cycle, the same mares were bred by a fertile stallion. At days 7, 10 and 13 post-ovulation intrauterine biopsies were collected. Immediately after sample collection, the mare's uteri were flushed, and those mares with embryo recovery were assigned to the Pregnant group. From ovulation detection until day of uterine biopsy, blood samples to measure Progesterone concentrations were collected daily in cyclic and pregnant mares. A larger blood vessel caliber was observed in pregnant mares than in cyclic from day 7-13. On the 7th day of pregnancy a large loss of ciliated cells was evident in the group of pregnant mares in comparison with the Cyclic group and the superficial cells of the endometrium were more protruded, and a small amount of histotrophic material between the folds was observed. On the 10th day of pregnancy, the glandular histotrophic secretion and the secretion of luminal epithelium became more intense than the secretion of cyclic mares. On the 13th day of pregnancy, a very large amount of histotroph was observed within large glandular openings surrounded by ciliated cells. The concentrations of P4 were affected by day (P < 0.001), but were not affected by group. Changes occurred in the uterine environment thereupon the entry of the embryo into the uterus. In the stroma and in the lumen, these modifications may aid to provide the necessary nutrition for the initial development of the embryo and to promote changes at cellular structures that will interact in the embryonic signaling and future fixation, implantation and placentation.

Management Strategies Aiming to Improve Horse Welfare Reduce Embryonic Death Rates in Mares.

The objective of this retrospective study was to evaluate the effect of management strategies aiming to improve animal well-being on pregnancy and embryonic death (ED) rates. Breeding records of a cohort of 1206 Thoroughbred mares brought to a stallion station facility, to be bred with the stallions housed there, were evaluated during ten breeding seasons. Mares were blocked according to management strategies in two groups: Stress and Relax. Strategies used to improve animal well-being (Relax group) were as follows: stopping the teasing routine, reducing or eliminating stall confinement, reducing the number of mares per group and maintaining herd stability during the breeding season. In barren mares, the pregnancy rate was higher in the Relax group (91.8%) when compared to the observed in Stress group (84.7%). However, no difference in pregnancy rates were observed (Stress = 85.2% vs. Relax = 86.2) in foaling mares. ED rate was higher in barren and foaling mares of the Stress group mares (25.5% and 26.8%, respectively) compared with the Relax group (16.1% and 14.7%, respectively). No significant differences were observed on foal heat pregnancy rate between groups; yet, the embryo loss on foal heat was significant reduced in Relax mares (Relax = 8.7% vs Stress = 24.5%). In conclusion, management strategies aimed to reduce social stress can reduce early pregnancy losses and the average cycles per pregnancy, improving reproductive performance in mares.

Proteomics of endometrial fluid after dexamethasone treatment in mares susceptible to endometritis.

Corticotherapy is a common treatment in mares susceptible to endometritis. Isoflupredone improves pregnancy rates and affects the protein profile of endometrial fluid in comparison to untreated mares. Dexamethasone decreases postbreeding fluid accumulation and uterine edema; however, its effects on the protein profile of the endometrial fluid have not yet been studied. The aim of the present study was to verify the effect of dexamethasone on the protein profile of endometrial fluid, in the presence or absence of infection, from mares susceptible to persistent postbreeding endometritis. Nine susceptible mares aged between 7 and 18 years were used. After checking for signs of estrus, mares were subjected to four treatments: C: mares received no treatment and served as control; D: mares received 40-mg dexamethasone at breeding, with collection of samples after 6 hours; I-6 and I-24: intrauterine infusion of 1 × 10(9)Streptococcus zooepidemicus/mL and samples collected after 6 and 24 hours; I/D-6 and I/D-24: intrauterine infusion of 1 × 10(9)S zooepidemicus/mL and 40-mg dexamethasone, collecting the sample after 6 and 24 hours. All mares were subjected to all treatments. Samples were collected and subjected to two-dimensional electrophoresis and mass spectrometry for the identification of relevant protein spots. Corticotherapy altered the protein profile of the endometrial fluid of susceptible mares, characterized by an increase and/or decrease in the optical density of inflammatory acute-phase proteins. We conclude that the use of dexamethasone in mares with and without infection alters the protein profile of endometrial fluid of susceptible mares.

Gene expression of matrix metalloproteinases and LH receptors in mare follicular development.

The period from the emergence of a dominant follicle until its formation requires tissue remodeling. Enzymes promoting collagen lysis, such as matrix metalloproteinases (MMPs), are fundamental for the process of extracellular matrix remodeling, which allows changes in ovarian tissue architecture during follicular growth. It has been suggested that the production of these enzymes may be affected by the rise in circulating concentrations of LH, which acts on the ovarian surface epithelium (OSE). The aim of this study was to determine the expression of MMP-1, MMP-2, and LH receptor (LHR) in the ovulation fossa and in the central portion of the equine ovary during follicular deviation and dominance. Ovaries of 12 cyclic mares were selected and subsequently divided into two groups: development (DEV) group and dominant (DOM) group. The DEV group consisted of ovaries from six animals whose follicles were less than 28 mm in diameter (follicular deviation), and the DOM group consisted of ovaries from six animals whose follicles measured 28 mm or more in diameter (dominant follicles). The latter group was divided into two subgroups: the group of ovaries with a dominant follicle (DOM-D) and the group of contralateral ovaries (DOM-C). Our results showed that mRNA for MMP-1, MMP-2, and LHR was present in the equine ovary during follicle development, in the ovulation fossa, and in the central portion of the ovary. MMP-1 and LHR gene expression was greater (P < 0.05) for the DOM-D group compared with the DOM-C group. In the DOM-D group, MMP-1, MMP-2, and LHR gene expression was greater (P < 0.05) in the ovarian stroma compared with the ovulation fossa. Using immunohistochemistry, OSE from the DOM group showed increased expression compared with the DEV group (P < 0.05). In conclusion, we demonstrated that MMP-1 and MMP-2 might be fundamental for events related to tissue remodeling, which occurs during follicular development until the formation of the dominant follicle. We also demonstrated the relationship between the gene expression of MMPs and the gene and protein expression of LHR, suggesting that LHR in the OSE might be an important factor to initiate the signaling cascade that culminates with the production of MMPs.

Recombinant expression and purification of the bovine acidic Seminal Fluid Protein

The acidic Seminal Fluid Protein (aSFP), a 12.9 kDa protein is a maker for bovine semen freezability possibly due to its antioxidant activity and effect on sperm mitochondrial function. However, its precise function on sperm preservation during freezing thaw is poorly understood. The use of recombinant DNA technology allows new approaches on the study of function and structure of proteins, and its production in procaryote systems offers several advantages. The present work describes the recombinant expression of the bovine aSFP and its binding properties. A cDNA library from the bovine seminal vesicle was used as template for amplification of the aSFP coding region. The amplicon was cloned into a pET23a (+) vector and transformed into E.coli BL21 pLysS strain. The recombinant expression was obtained in E coli. One step ion immobilized affinity chromatography was performed, resulting in high yield of purified protein. To determine the bioactivity of the r aSFP, the protein was incubated in different concentrations with 10 7 spermtozoa at 37°C for 5 h. Western blotting and fluorescence microscopy analyses showed the ability of the recombinant aSFP to attach to the spermatozoa. Based on our results, the described method can be used to obtain mg levels of recombinant aSFP.

Resposta reprodutiva de vacas de corte associada a marcadores moleculares relacionados à fertilidade / Reproductive performance of beef cattle cows associated with molecular markers related to the fertility

O objetivo deste estudo foi buscar associação entre a taxa de prenhez após inseminação e natalidade com marcadores moleculares ligados aos genes do receptor para IGF-1, LHβ, Leptina e receptores do FSH e LH. Utilizaram-se 249 vacas adultas Aberdeen Angus, das quais 199 foram submetidas a protocolos distintos para a IATF, seguida pelo repasse com touros, e 50 vacas formaram o grupo controle representado pelo acasalamento com touros. Foram avaliados o escore de condição corporal (ECC) e o escore de condição ovariana (ECO) ao início da estação reprodutiva. O ECC influenciou a taxa de natalidade, respectivamente de 55,6%, 75,8% e 82,4% (P<0,05) para os animais com ECC menor que 2,5, entre 2,5 a 2,9, e maior ou igual a 3,0, por ocasião da estação reprodutiva. Os marcadores relacionados ao gene do receptor para o IGF-1 (AFZ-1 e HEL5) mostraram associação com a taxa de natalidade. Vacas homozigóticas para o marcador AFZ-1 apresentaram 84,4% de natalidade em comparação às heterozigóticas, com 71,5% (P<0,05). A presença do alelo*161 para o marcador HEL5 foi negativa sobre a natalidade, respectivamente de 33,3% e 76,5% para vacas com e sem esse alelo (P<0,05). Esses resultados demonstram uma importante associação entre os marcadores envolvidos com o receptor para o IGF-1 e desempenho reprodutivo de vacas Angus.

The association between the reproductive performance, expressed by pregnancy rate at fixed timed artificial insemination and birth rate in the subsequent season in beef cows, and molecular markers linked to genes for IGF-1 receptor, LHβ, leptin, and FSH and LH receptors were evaluated. Data from 249 Aberdeen Angus adult cows were used in this study. One hundred and ninety-nine cows were subjected to four different protocols for FTAI, followed by clean-up bulls and 50 cows formed the control group, matted only with bulls for 90 days during the mating season. Body condition score (BCS) and ovarian condition score (OCE) were evaluated at the beginning of the breeding season. The birth rate in the following year was 75.5%, with no treatments influence. The BCS has influenced the birth rate, respectively 55.6%, 75.8% and 82.4% (P<0.05) for animals with BCS less than 2.5; 2.5 to 2.9; and greater than or equal to 3.0, at the beginning of the breeding season. The markers related to IGF-1 receptor gene (AFZ-1 and HEL5) were associated with the birth rate in beef cows. Cows homozygous for AFZ-1 marker showed 84.4% of birth rate, while heterozygous cows showed 71.5% (P <0.05). The presence of allele *161 to the HEL5 marker was negative on birth rate. Cows with this allele had only 33.3% of birth rate, while cows without this allele had 76.5% of birth rate (P <0.05). These results demonstrate a significant association between the markers involved with the IGF-1 receptor and reproductive performance of Aberdeen Angus beef cows.

A novel strategy of mesenchymal stem cells delivery in the uterus of mares with endometrosis.

Mesenchymal stem cells (MSCs), because of their immunomodulation and trophic activities, in addition to their capacity to regenerate damaged tissues, have potential for treatment of many diseases. The success of stem cell therapies depends, in part, on the method of cell delivery, which should provide wide cell distribution and homing in to injured sites. The objective of the present study was to developing a novel strategy for delivery of MSCs into the uterus of mares with endometrosis (degenerative alteration of uterine glands and surrounding stroma). Endometrosis was confirmed in all mares (N = 6) used in this study. To trace multipotent equine adipose tissue-derived MSCs (eAT-MSCs) in endometrial tissue, before transplantation, cells were stained with a fluorescent dye. During a synchronized estrus, the eAT-MSCs (2 × 10(7) diluted in 20 mL of sodium chloride 0.9%) were inoculated into uterus using a simple technique, similar to artificial insemination (AI) in mares. At 7 and 21 days after transplantation, homing of fluorescently labeled eAT-MSCs was observed by confocal microscopy of uterine biopsies collected from the uterine body and in both uterine horns, including glandular and periglandular spaces, in three of four treated mares. Herein, we propose a new method of MSCs delivery in uterus of mares with endometrosis, which was minimally invasive and technically simple.

Retardo da realização da IATF sobre o desempenho reprodutivo na estação de acasalamento de vacas de corte lactantes / Delay of beginning to FTAI on reproductive performance during to mating season of beef lactating cows

Compararam-se efeitos de diferentes protocolos para a IATF com o acasalamento natural (Controle) sobre o desempenho reprodutivo de 249 vacas Aberdeen Angus, distribuídas em cinco grupos: Controle (n=50); Crestar 2º uso (n=64); OvSynch (n=65); Primer 1ºuso (n=35) e Primer 2º uso (n=35). A IATF dos animais dos grupos Crestar 2º uso, OvSynch, e Primer 1º uso foi realizada 27 dias após o início da estação do grupo controle e a IATF do grupo Primer 2º uso ocorreu 38 dias após o início da estação do grupo-controle. A partir de sete dias após a IATF, os animais foram submetidos ao repasse por touros até o término da estação de acasalamento, que foi de 91 dias para o grupo-controle, 64 dias para os grupos Crestar 2º uso, OvSynch e Primer 1º uso e de 53 dias para o grupo Primer 2º uso. A taxa de gestação ao final da estação de acasalamento não se diferenciou entre os grupos (P>0,05), sendo de 85,9%; 83,1%; 82,9%; 88,6% e 80,0%, respectivamente, para Crestar 2º uso; OvSynch; Primer 1º uso; Primer 2º uso e Controle. A taxa de parição resultante da IATF foi de 23,4%; 29,2%; 48,6% e 62,9% para os grupos Crestar 2º uso, OvSynch, Primer 1º uso, Primer 2º uso, respectivamente, com diferença significativa (P<0,05) entre Crestar e Primer 1º e 2º uso. OvSynch não se diferenciou de Crestar e Primer 1º uso. Primer 1º uso não se diferenciou de Primer 2º uso. A perda gestacional, do diagnóstico de gestação ao nascimento, foi de 10,5%. O intervalo de partos estimado (IEP) não apresentou diferenças, com média de 478 dias. O escore de condição corporal (ECC) de fêmeas gestantes ao final da estação reprodutiva foi diferente do de fêmeas não gestantes (controle), mas não dos demais grupos, possivelmente pela influência do tratamento em induzir a ciclicidade dos animais com ECC inferior. O atraso da realização da IATF após 27 ou 38 dias do início da estação de acasalamento não afetou a taxa de gestação final e o IEP dos animais, quando comparado ao acasalamento por touros.

The effects of different FTAI protocols were compared to the natural mating of bulls on the reproductive performance of 249 Aberdeen Angus cows. Five groups were formed: Control (n=50); Crestar 2nd use (n=64); OvSynch (n=65); Primer 1st use (n=35) and Primer 2nd use (n=35). The FTAI of the animals in the Crestar 2nd use, OvSynch and Primer 1st use groups was accomplished 27 days after the beginning of the mating season for the control group and the FTAI in the Primer 2nd use group happened 38 days after the beginning of the mating season of the control group. From seven days after the FTAI cows were exposed to bulls until the end of the mating season. The mating season was of 91 days for the control group, 64 days for the Crestar 2nd use, OvSynch and Primer 1st use groups and 53 days for the Primer 2nd use group. The pregnancy rate at the end of the mating season didn't differ among the groups (P>0.05), being 85.9; 83.1; 82.9; 88.6 and 80.0% respectively, for Crestar 2nd use, OvSynch, Primer 1st use, Primer 2nd use and Control. The birth rate resulting from FTAI was 23.4; 29.2; 48.6 and 62.9% for the Crestar 2nd use, OvSynch, Primer 1st use, Primer 2nd use groups, with significant difference (P<0.05) among Crestar and Primer 1st and 2nd use. OvSynch didn't differ in Crestar and Primer 1st use. Primer 1st use didn't differ from Primer 2nd use. The average reproductive losses between the gestation diagnosis and the birth were10.5%. The estimated calving interval (CI) didn't present differences among the animal groups, with an average of 478 days. The body condition score (BCS) of pregnant cows at the end of the reproductive station differed from BCS of empty cows in the control group, but it didn't differ in the other groups, possibly due to the hormonal treatment influence in inducing the oestrus and ovulation in animals with lower BCS. The delay of the accomplishment of FTAI after 27 or 38 days of the beginning of the mating season didn't affect the final pregnancy rate and CI of the cows, when compared to natural mating.

Effect of corticotherapy on proteomics of endometrial fluid from mares susceptible to persistent postbreeding endometritis.

The objective was to determine the effects of corticotherapy, in the presence and absence of uterine inflammation, on proteomics of endometrial fluid from mares susceptible to endometritis. In 11 mares, estrus was induced seven times with 5 mg PGF(2α) given at 14-day intervals. The first estrus was a control (no treatment). During the third estrus, mares received glucocorticoid (GC) treatment (20 mg isoflupredone acetate) every 12 h, for three consecutive days. The fifth estrus was the Infected treatment (intrauterine infusion of 1 × 10(9) colony-forming unit/mL Streptococcus equi subspecies zooepidemicus). Finally, the seventh was a combination of GC + Infected treatment (infusion of bacteria 24 h after the first GC treatment). At 12 h after the end of each treatment, uterine samples were collected and submitted to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) for protein separation and mass spectrometry. Both GC treatment and uterine lumen infection induced proteomic alterations in the endometrial fluid of susceptible mares, characterized by an increase, decrease, or both in the relative optic density and/or frequency of inflammatory acute phase proteins (APP), with major alterations occurring when corticotherapy was applied in the presence of an infectious process. Corticotherapy in the presence of infection increased α(1)-antitrypsin (AAT), transthyretin (TT), and actin, but reduced immunoglobulin G, whereas intrauterine infection increased haptoglobin (Hp) and apolipoprotein A-1 (ApoA-1) and decreased transferrin (TF). Infection reduced levels of α(1)-antitrypsin and transthyretin, whereas corticotherapy in the presence of infection increased their frequency. We concluded that GC influenced the immune response, not only as suppressors, but also as enhancers of local defense mechanisms, through an immunomodulatory action. Short-term corticotherapy could be beneficial for treatment of uterine infectious processes in the mare.

Two-dimensional polyacrylamide gel electrophoresis of equine seminal plasma proteins and their relation with semen freezability.

The objective was to evaluate protein profiles of equine seminal plasma using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and to determine whether any of these proteins were related to semen freezability. Seminal plasma was collected from 10 stallions, of high and low semen freezability, housed at the State Stud of Lower Saxony, and routinely used in AI programs. Twenty-five protein spots were identified from the two-dimensional gel (12%), seven of which were present in all samples (all proteins were identified by MALDI-MS). Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been used to generate ion images of samples in one or more mass-to-charge (m/z) values, providing the capability of mapping specific molecules to two-dimensional coordinates of the original sample. Of the 25 proteins identified, two spots had greater relative content (P < 0.05) in seminal plasma samples collected from stallions with high semen freezability: spot 5 (80-85 kDa, isoelectric point [pI] 7.54), identified as CRISP-3; and spot 45 (18.2 kDa, pI 5.0-5.2), identified as HSP-2. Conversely, protein content was greater (P < 0.05) in seminal plasma samples from stallions with low semen freezability: spot 7 (75.4 kDa, pI 6.9-7.4), identified as lactoferrin; spot 15 (26.7 kDa, pI 5.51), identified as kallikrein; spot 25 (25 kDa, pI 7.54), identified as CRISP-3; and spot 35 (13.9 kDa, pI 3.8-4.2), identified as HSP-1. In conclusion, there were differences in the seminal plasma protein profile from stallions with high and low semen freezability. Furthermore, CRISP-3 and HSP-2 were potential seminal plasma markers of high semen freezability.

Miniature ponies: 1. Follicular, luteal and endometrial dynamics during the oestrous cycle.

Follicular dynamics were studied during 12 interovulatory intervals (IOIs) and 36 preovulatory periods in Miniature mares. The percentage of IOIs with the following follicle events was: ovulatory wave with only one follicle>or=10 mm (55%), diameter deviation similar to previous reports in larger mares (25%) and minor waves emerging before or after the ovulatory wave (55%). Follicle data were compared among Miniature ponies, large ponies and Breton horses (n=12 IOIs per breed). The IOI was longer (P<0.001) in Miniature ponies (23.3+/-0.9 days) and in large ponies (23.9+/-0.5 days) than in Breton horses (20.3+/-0.7 days). The Miniature ponies had fewer (P<0.0001) growing follicles>or=10 mm per ovulatory wave (1.5+/-0.3) and more (P<0.0004) ovulatory waves (6/11) with only one follicle>or=10 mm than large ponies (9.8+/-0.8 and 0/12) and horses (5.8+/-0.9 and 0/12). Maximum diameter of the preovulatory follicle was smaller (P<0.003) in the Miniature ponies (38.3+/-0.7 mm) than in the horses (44.5+/-1.4 mm), but the difference between breeds was slight (6%) compared with the difference in bodyweight (65%). Considering the small number of follicles per ovulatory wave, Miniature mares are a potential model for comparative studies in folliculogenesis within and among species.

Miniature ponies: 2. Endocrinology of the oestrous cycle.

Plasma concentrations of FSH, LH, oestradiol and progesterone were studied daily during 12 interovulatory intervals and 21 periovulatory periods in nine Miniature ponies. The peak of the FSH surge that was temporally associated with emergence of the future ovulatory follicle occurred when the follicle was approximately 9 mm, compared with a reported diameter of 13 mm in larger breeds. The ovulatory LH surge involved a slow increase between Days 13 and 18 (ovulation=Day 0; 0.6+/-0.1 ng day(-1)), a minimal increase or a plateau on Days 18 to 21 (0.04+/-0.1 ng day(-1)), and a rapid increase after Day 21 (2.2+/-0.4 ng day(-1); P<0.0001). The end of the plateau and the beginning of the rapid increase occurred on the day of maximum concentration in the oestradiol preovulatory surge. An unexpected mean increase and decrease in LH occurred (P<0.04) on Days 5 to 9. Concentrations of oestradiol and progesterone seemed similar to reported results in larger breeds. Results indicated that in Miniature ponies the peak of the FSH surge associated with emergence of the future ovulatory follicle occurred at a smaller diameter of the future ovulatory follicle than in larger breeds, the ovulatory LH surge increased in three phases, and the ovulatory LH surge was followed by an LH increase and decrease during the early luteal phase.