Mammals have a circadian rhythm that is synchronized by a master clock located in the hypothalamic suprachiasmatic nucleus (SCN). The SCN regulates additional clocks located in peripheral tissues, including some involved in endocrine or reproductive functions. Studies in humans and mice report that molecular clocks also exist in the placenta. However, little is known about the presence of “Clock genes,” namely Circadian Locomotor Output Cycles Kaput (CLOCK), Brain and Muscle Arnt-Like 1 (BMAL1), Period 1 (PER1), Period 2 (PER2), Cryptochrome 1 (CRY1), and Cryptochrome 2 (CRY2), in equine placenta. Pregnancy length in mares varies and shows fluctuations in hormone concentrations throughout pregnancy. We postulate that similar to humans and mice, Clock genes are present in the horse placentas. Our goal was to determine if relative levels of clock genes were different between placentas associated with males and female fetuses or correlated with gestational length. We used polymerase chain reaction and immunofluorescence to study the presence of CLOCK, BMAL1, PER1, PER2, CRY1, and CRY2 in full-term mare placentas. Clock genes were present in all placentas, with significant lower levels of CRY2 and CLOCK in placentas that were associated with male fetuses. There was no association between relative levels of Clock genes and gestational length. These data provide the stage for future studies aimed at uncovering a function for Clock genes in the horse placenta.

Newborn foals are dependent on ingestion of high-quality colostrum for their immune protection. Colostrum quality (immunuoglobulin G [IgG]) can be determined by the single radial immunodiffusion (SRID) test or estimated by Brix refractometer. Goal was to compare SRID test findings (IgG concentrations) and Brix refractometer readings (IgG percentage) in colostrum samples collected from mares during the first 12 - 18 hours postpartum. A total of 56 colostrum samples were collected from 10 postpartum mares. Postfoaling, colostrum IgG concentrations were 21,785 ± 5,592 mg/dl and IgG percentage was 27.9 ± 3.7%. At 12 hours postfoaling, IgG concentrations decreased to 1,713.9 ± 1,380.4 mg/dl and its percentage to 11.4 ± 1.6%. There was a high correlation (r = 0.9661) between SRID test results and Brix refractometry scores. In summary, Brix refractometry can be used to monitor colostrum quality.

Pharmacologically induced ejaculation is utilized in stallions when traditional semen collection procedures are not appropriate or not effective. Most common protocol includes oral imipramine hydrochloride, with intravenous xylazine hydrochloride given 1 - 2 hours later. Goal was to document success rate from past clinical experience (historical data) and to determine whether addition of oxytocin along with xylazine or a prostaglandin analogue prior to xylazine treatment would enhance success rate in aged stallions in a clinical setting. Semen was successfully collected in 3 of 7 aged stallions using the standard protocol. In the modified protocol, 22 times (out of 50 attempts) semen was successfully collected from 12 stallions. However, addition of oxytocin or a prostaglandin analog had a deleterious effect on passive emission of semen.

No abstract

No abstract