Iron Horse Equine Reproduction Services

10/16/2026

We have frozen semen in our tanks now 29 years old. Good to know it is keeping well stored in the liquid nitrogen tanks!

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐋𝐨𝐧𝐠-𝐓𝐞𝐫𝐦 𝐋𝐢𝐪𝐮𝐢𝐝 𝐍𝐢𝐭𝐫𝐨𝐠𝐞𝐧 𝐒𝐭𝐨𝐫𝐚𝐠𝐞 𝐄𝐟𝐟𝐞𝐜𝐭𝐬 𝐨𝐧 𝐅𝐫𝐨𝐳𝐞𝐧 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧 𝐒𝐞𝐦𝐞𝐧 𝐐𝐮𝐚𝐥𝐢𝐭𝐲 𝐚𝐧𝐝 𝐌𝐞𝐬𝐬𝐞𝐧𝐠𝐞𝐫 𝐑𝐍𝐀 𝐀𝐛𝐮𝐧𝐝𝐚𝐧𝐜𝐞

Cryopreserved semen stored in liquid nitrogen is widely assumed to maintain fertility indefinitely, yet emerging reports suggest possible long-term quality decline. This study examined whether extended storage duration affects conventional s***m quality parameters and fertility-associated messenger RNA abundance in commercially cryopreserved stallion semen.

Study Design:
• 18 stallions (Warmblood, Thoroughbred, Lipizzaner); semen cryopreserved between 1998 and 2024; storage duration 0–26 years
• Post-thaw assessment: concentration, motility, membrane integrity, mitochondrial membrane potential, and chromatin condensation
• Messenger RNA extracted from 12 semen batches; abundance of 10 fertility-associated genes measured by quantitative reverse transcription polymerase chain reaction
• Spearman correlation analysis performed between all endpoints and storage duration

Key Results:
• No significant correlations between storage duration and any conventional s***m quality parameter
• No significant correlations between storage duration and messenger RNA quality metrics
• Four genes showed significant negative correlations with storage duration:
•• Protamine 1 (r=–0.338)
•• Protamine 3 (r=–0.373)
•• Peroxiredoxin 6 (r=–0.336)
•• Cysteine-rich secretory protein 3 (r=–0.507)

Conclusions:
• Conventional s***m quality is not meaningfully affected by liquid nitrogen storage for up to 26 years
• Fertility-associated messenger RNA abundance does decline with extended storage duration for select candidate genes
• Major s***m quality changes occur at cryopreservation processing, not during subsequent storage
• Larger sample sizes are needed to confirm messenger RNA findings

(Vigolo V, Ertl R, Aurich C. 2025. Long-term storage does not result in considerable changes of frozen stallion semen characteristics but affects semen mRNA abundance. Journal of Equine Veterinary Science 145:105332. https://doi.org/10.1016/j.jevs.2024.105332)

09/22/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐩𝐞𝐫𝐦 𝐌𝐞𝐦𝐛𝐫𝐚𝐧𝐞 𝐋𝐢𝐩𝐢𝐝 𝐏𝐫𝐨𝐟𝐢𝐥𝐞 𝐃𝐢𝐟𝐟𝐞𝐫𝐞𝐧𝐜𝐞𝐬 𝐁𝐞𝐭𝐰𝐞𝐞𝐧 𝐏𝐨𝐨𝐫 𝐚𝐧𝐝 𝐆𝐨𝐨𝐝 𝐅𝐫𝐞𝐞𝐳𝐞𝐫 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧𝐬

Study Design:
• 39 stallions with established fertility & cryopreservation histories; 2 ej******es each
• Classified as poor freezers (n=19): total motility 20%
• Lipid profiles obtained via mass spectrometry; differential expression analyzed by analysis of variance with Tukey's test & volcano plot

Key Results:
• Five phospholipid classes were significantly more abundant in poor freezer stallions:
•• Glycerophosphoethanolamines
•• Glycerophosphoglycerols
•• Glycerophosphoinositols
•• Glycerophosphoserines
•• Simple glucosylceramide series
• Differentially expressed lipids were characterized by long carbon chain lengths (31–39) & high polyunsaturation
• Lipid class patterns varied consistently between groups across multiple phospholipid families, reflecting changes in the s***m membrane lipid profile between poor & good freezers.

Conclusions:
• S***m membrane lipid profile composition is a significant determinant of cryopreservation tolerance in stallions
• Long-chain polyunsaturated fatty acids in the plasma membrane appear to be critical negative regulators of cryoresistance, further supporting the impact of the s***m membrane lipid profile on fertility preservation outcomes.
• Lipidomic profiling offers a novel tool for predicting freezing suitability & informing targeted fertility preservation strategies. In summary, future research should continue to investigate the s***m membrane lipid profile to improve cryopreservation techniques in stallions.

(Ramires Neto C, Freitas-Dell'Aqua CP, Sancler-Silva YFR, Belaz KR, Zampieri D, Tata A, Eberlin M, Papa FO, Dell'Aqua Jr JA, Alvarenga MA. 2025. Lipid profile differences in semen from "bad" and "good" freezer stallions. Journal of Equine Veterinary Science 145:105315. https://doi.org/10.1016/j.jevs.2024.105315)

09/21/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐏𝐨𝐬𝐭-𝐓𝐡𝐚𝐰 𝐒𝐩𝐞𝐫𝐦 𝐌𝐨𝐭𝐢𝐥𝐢𝐭𝐲 𝐂𝐨𝐦𝐩𝐚𝐫𝐢𝐧𝐠 𝐀𝐮𝐭𝐨𝐦𝐚𝐭𝐞𝐝 𝐅𝐫𝐞𝐞𝐳𝐞𝐫 𝐯𝐬. 𝐒𝐭𝐲𝐫𝐨𝐟𝐨𝐚𝐦 𝐁𝐨𝐱 𝐀𝐜𝐫𝐨𝐬𝐬 𝐌𝐮𝐥𝐭𝐢𝐩𝐥𝐞 𝐂𝐫𝐲𝐨𝐩𝐫𝐨𝐭𝐞𝐜𝐭𝐚𝐧𝐭𝐬

Study Design:

• 4 stallions (ages 4–20); 4 semen collections each
• Four cryoprotectant groups tested:
• Glycerol + methylformamide (2% + 1%)
• Ethylene glycol + methylformamide (2.5% + 2.5%)
• Glycerol + methylformamide (2.5% + 2.5%)
• Standard commercial control extender
• Two freezing methods per group: isothermal styrofoam box & automated computer-controlled freezer
• Post-thaw assessment: total motility, progressive motility, rapid s***m percentage, average path velocity, straight-line velocity, & curvilinear velocity

Key Results:

• No significant differences in total motility, progressive motility, rapid s***m percentage, or average path velocity across groups or methods
• Straight-line velocity was lower in the ethylene glycol group using the box versus the control box & glycerol/methylformamide machine groups
• Curvilinear velocity was highest in the standard control box protocol, outperforming all other group/method combinations

Conclusions:

• When the automated freezing machine vs. Styrofoam box are compared, both freezing methods are effective; all cryoprotectant combinations produced acceptable post-thaw motility
• The automated machine offers greater process consistency by eliminating external variables such as nitrogen level & straw quantity
• Individual cryoprotectant combinations may influence velocity parameters even when primary motility metrics remain comparable

(Canuto LEF, Trinque CM, Cavalero TMS, Frasson MA, de Zutter BM, Zanlorenzi Silva LP, Baby MEA, Freitas-Dell'Aqua CP, Alvarenga MA, Papa FO. 2025. Post-thaw semen motility in different cryoprotectants after freezing in a Cryogen® automatic freezer compared to an isothermal box. JEVS 145:105272 - https://www.sciencedirect.com/science/article/abs/pii/S0737080624002788)

09/21/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐞𝐦𝐞𝐧 𝐌𝐢𝐜𝐫𝐨𝐛𝐢𝐨𝐦𝐞 𝐈𝐧𝐟𝐥𝐮𝐞𝐧𝐜𝐞 𝐨𝐧 𝐭𝐡𝐞 𝐌𝐚𝐫𝐞 𝐔𝐭𝐞𝐫𝐢𝐧𝐞 𝐌𝐢𝐜𝐫𝐨𝐛𝐢𝐨𝐦𝐞

While semen-uterine microbiome interactions have been described in humans, equivalent data in horses was absent. Using a cross-species insemination model, this study investigated whether the male seminal microbiome influences the mare uterine microbiome and whether post-breeding microbiome composition affects embryo recovery.

Study Design:

• 22 fertile mares inseminated with raw semen (2 billion s***m) from either a donkey jack or horse stallion in a cross-over design with washout cycle between treatments
• Uterine fluid sampled before insemination, at 6 hours, 24 hours, and 8 days post-ovulation at embryo flush
• Bacterial DNA sequenced via full-length 16S region; taxonomic analysis performed to family level

Key Results:

• Semen microbial diversity differed significantly between donkey and horse (p=0.048)
• Dominant phyla in both groups: Proteobacteria, Actinobacteria, and Firmicutes — proportions differed between species
• Lactobacillales contributed up to 20% of uterine microbiome in donkey-bred mares versus 6% in horse-bred mares
• 24 bacterial families shared between donkey semen and post-insemination uterine microbiome; 9 shared between horse semen and uterine microbiome
• Uterine microbiome composition at 8 days post-ovulation differed significantly based on embryo recovery outcome (p=0.02)

Conclusions:

• Semen microbiome composition demonstrably influences the mare uterine microbiome post-breeding
• A temporary combined male-female microbiome appears to have measurable consequences for embryonic recovery
• First demonstration in horses of a semen-to-uterus microbiome transfer effect

(Podico G, Canisso IF. 2025. The semen microbiome influences the mare uterine microbiome. JEVS 145:105314 - https://doi.org/10.1016/j.jevs.2024.105314)

09/15/2026

We are travelling to Saskatchewan this coming weekend September 18-21 for our annual Reproduction Workshops with Avante Garde Canadians! Looking forward to a great weekend of education and hands on learning experience! Let’s do this!

09/15/2026

IHE X’Royal Halo placed 2nd in her 2nd ever eventing competition!! Super proud breeder moment!

08/20/2026

Morphology better indicator than motility… S***m Motility actually has a 0.56 correlation to fertility yet so many put an emphasis on it.

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐞𝐦𝐞𝐧 𝐀𝐬𝐬𝐞𝐬𝐬𝐦𝐞𝐧𝐭 𝐚𝐬 𝐚 𝐅𝐞𝐫𝐭𝐢𝐥𝐢𝐭𝐲 𝐏𝐫𝐞𝐝𝐢𝐜𝐭𝐨𝐫 𝐢𝐧 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧𝐬

Accurate stallion semen assessment as a fertility predictor need not rely on expensive equipment. This study investigated whether basic light microscopy assessments of s***m motility, membrane integrity, and morphology could reliably distinguish fertile from sub-fertile stallions under field conditions.

Study Design:

• 24 frozen semen batches from 24 Arabian and Straight Egyptian Arabian stallions
• Semen frozen across Europe and the Middle East; used for artificial insemination in Doha, Qatar
• All straws standardized at 100 million s***m cells; thawed at 37°C for 1 minute
• Eosin-Nigrosin stain (Botuvital, Botupharma) used to assess membrane integrity and morphology under light microscopy
• 200 cells evaluated per sample; categorized as major, minor, total, and non-compensatory defects
• Mares inseminated once at ovulation; pregnancy confirmed by ultrasound at 14 days

Key Results:

• Major s***m pathologies, total pathologies, and non-compensatory defects were all significantly associated with pregnancy outcome (p

07/19/2026

We are travelling with our mobile unit to collect and freeze stallions in Quebec July 30-Aug 2. If anyone is interested in our services, pm us! Our portable phantom requires secure footing for 2’ stakes to be pounded into ground.

07/06/2026

💥𝐈𝐒𝐒𝐑 𝐒𝐧𝐢𝐩𝐩𝐞𝐭!🐴 𝐒𝐭𝐚𝐥𝐥𝐢𝐨𝐧 𝐃𝐢𝐬𝐦𝐨𝐮𝐧𝐭 𝐋𝐚𝐭𝐞𝐧𝐜𝐲 𝐚𝐧𝐝 𝐏𝐫𝐞𝐠𝐧𝐚𝐧𝐜𝐲 𝐎𝐮𝐭𝐜𝐨𝐦𝐞𝐬 𝐢𝐧 𝐓𝐡𝐨𝐫𝐨𝐮𝐠𝐡𝐛𝐫𝐞𝐝 𝐇𝐨𝐫𝐬𝐞𝐬

In Thoroughbred natural service breeding, dismount semen — residual urethral semen collected after copulation — is routinely used as a proxy for ej*****te quality. This study investigated whether the duration a stallion remains mounted post-ej*******on (stallion dismount latency) influences both dismount sample composition and pregnancy outcomes.

Study Design:

• 62 Thoroughbred stallions
• Dismount latency defined as time from ej*******on start to pe**le withdrawal
• Dismount samples analyzed for s***m concentration and motility parameters
• Pregnancy outcomes correlated with dismount latency using regression and one-tailed t-tests

Key Results:

• S***m concentration in dismount samples negatively correlated with dismount latency — shorter stallion dismount latency yielded higher-quality samples
• Total motility showed a similar negative trend with dismount latency, though not statistically significant
• Progressive motility, straightness, and average path velocity showed no significant correlation with dismount latency
• Stallion dismount latency was significantly longer in cycles resulting in pregnancy (11.1 vs. 10.2 seconds; p≤0.05)

Interpretation:

• Prolonged stallion dismount latency likely results in more s***m being deposited directly into the uterus rather than retained in the va**na
• Shorter dismount latency is associated with premature withdrawal, leaving more residual s***m in the dismount sample

Conclusions:

• Longer dismount latency improves pregnancy outcomes and should be encouraged through management strategies
• Paradoxically, higher-quality dismount samples are associated with poorer pregnancy rates
• Stallion dismount samples are unreliable proxies for ej*****te fertility and should be interpreted with caution.

(Medica A, Griffin R, Swegen A, Gibb Z. (2025) Prolonged dismount latency and its relationship with pregnancy outcomes in Thoroughbred horses. JEVS 145:105304 - abstract on-line at https://www.sciencedirect.com/science/article/abs/pii/S0737080624003101)