Search

Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups, the resulting conceptuses were collected 21 days after transfer to assess conceptus development. HE mares became obese, and embryos recovered from HE mares were more likely to succumb to early embryonic death. The period of annual cyclicity was extended in HE compared to control mares in all years. The incidence of HAFs did not consistently differ between HE and control mares. No differences in embryo morphometric parameters were apparent. In conclusion, consuming a HE diet extended the duration of cyclicity, and appeared to increase the likelihood of embryos undergoing early embryonic death following embryo transfer.

Background: Overfeeding is associated with obesity and insulin dysregulation (ID), which are both risk factors for equine metabolic syndrome. How chronic overfeeding affects development of these factors is poorly understood. Objectives: To examine the influence of long-term high-energy diet provision on body condition and ID. Animals: Eleven Shetland pony mares. Methods: In a 3-phase study, the high-energy group (n = 7) was fed 200% of net energy (NE) requirements (hay; concentrate: 36% sugar and starch, 13% fat) for 24 weeks, followed by 17 weeks hay-only feeding before resuming the high-energy diet (n = 4) for an additional 29 weeks. Mares were weighed weekly. Oral glucose tolerance tests were performed 3 to 4 times per dietary period. Results were compared with those of a control group (phase 1, n = 4; phases 2 and 3, n = 6) that received 100% NE requirements, using a general linear mixed model with post hoc Bonferroni testing. Results: The mean body weight of the high-energy group increased by 27% per high-energy feeding period. During both feeding periods, area under the curve (AUC) for plasma glucose concentration decreased (P

Introduction Placental imprinted genes appear to be sensitive indicators of an inappropriate pre-implantation environment. This study examined the effects of negative uterine asynchrony after embryo transfer (ET) on early horse embryo development, and yolk-sac membrane expression of DNA methyltransferases (DNMTs) and equine specific placental imprinted genes. Methods Day 8 embryos were transferred to recipient mares on day 8 (synchronous) or day 3 (asynchronous) after ovulation, and conceptuses were recovered 6 or 11 days later (day 14 or 19 of development). Results Day 14 conceptuses recovered from an asynchronous uterus had a smaller embryonic disc, in which primitive streak development was visibly retarded compared to conceptuses from a synchronous uterus. Similarly, length, somite number and organogenesis were retarded in day 19 embryos after asynchronous ET. Maternal ( GRB10 , H19 , IGF2R , PHLDA2 ) and paternal ( IGF2 , INSR , PEG3 , PEG10 , DIO3 , NDN , SNRPN ) imprinted genes and DNMTs ( DNMT1 , 3A and 3B ) were all up-regulated between day 14 and 19 of pregnancy and, for most, mRNA expression was higher in synchronous than asynchronous day 19 yolk-sac membrane. Expression of the paternally imprinted gene HAT1 increased between day 14 and 19 of pregnancy, but was not affected by the asynchrony. Discussion Conceptus development and upregulation of DNMTs and imprinted genes were delayed rather than dysregulated after transfer into a negatively asynchronous uterus. We propose that this ability to ‘reset’ conceptus development to uterine stage is an adaptation that explains why horse embryos are unusually tolerant of asynchrony after ET.

The location of an undescended testicle influences the choice of surgical technique for efficient cryptorchid castration. We review a standardized protocol for preoperative examination to dictate surgical approach to cryptorchidism. Cases are split into two periods: 2004–2006 and 2007–2014. In 2004–2006, conventional cryptorchidectomy and laparoscopic cryptorchid castration (standing) were both offered, but the choice of technique was based primarily on owners' preference for a recumbent or standing procedure. In 2007–2014, ultrasonography was used to locate the testes and dictate the preferred surgical approach; for abdominal testes, laparoscopic intraabdominal spermatic cord ligation without orchidectomy was preferred and for inguinal testes, conventional open orchidectomy. The numbers of animals requiring a second procedure to complete castration were compared between the two periods. In addition, failure rates for individual testes grouped by location were determined separately for the different techniques, and the value of preoperative ultrasonography to locate the retained testes was assessed. In 2004–2006, 15.3% (20/131) of the cryptorchids needed more than one surgery to complete castration, compared to 0.7% (1/144) in 2007–2014. Failure rates for laparoscopic castration were 0/168 (0%) for abdominal, 3/40 (7.5%) for inguinal, and 9/55 (16.4%) for scrotal testes; for conventional castration, failure was recorded for 3/12 (25%) abdominal and 0/92 (0%) inguinal testes. For 94% (156/166) of retained testes, ultrasound-based preoperative advice on surgical approach was correct. Using a standardized preoperative examination to determine choice of surgical technique significantly (P < .001) reduced the number of second surgeries needed to complete castration. Preoperative ultrasound is therefore a useful aid to determining the surgical approach to cryptorchid castration.