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  • Author: J. J. LUCAS x
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J. J. LUCAS, B. W. PICKETT and R. J. KOMAREK

Summary.

Semen records of ten ejaculates from each of ten Yorkshire boars were used to estimate the boar and ejaculate variance components for eleven semen characteristics. These data were used to estimate the power of the test. In ten of eleven characteristics, a minimum of five boars and five ejaculates per boar provided at least a 90% chance of detecting a difference of 50% of the mean. For these same ten characteristics, a minimum of fourteen boars and forty-three ejaculates per boar provided at least a 90% chance of detecting a difference of 25% of the mean.

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S. K. Wasser, R. Thomas, P. P. Nair, C. Guidry, J. Southers, J. Lucas, D. E. Wildt and S. L. Monfort

A study was conducted in captive baboons to determine (i) the impact of cereal dietary fibre on faecal progestogen excretion, and (ii) whether means of controlling dietary effects could be identified. Blood was collected on 3 days per week and faeces on 5 days per week from four unanaesthetized cyclic female baboons, consecutively fed three diets of 5, 10 and 20% fibre for 90 days per diet. A 2 day lag time was detected before progesterone in the blood appeared in the faeces, regardless of diet (mean correlation was 0.62, P = 0.002). Increased dietary fibre had a negative effect on progestogen excretion (P < 0.004). Correspondence between blood and faecal progestogens was consistently greatest and the effect of dietary fibre least when faecal progestogens were expressed g−1 dry faeces. Several means of indexing faecal steroid excretion rates were examined including dehydroepiandrosterone (DHEA) and a number of byproducts of cholesterol metabolism. The cholesterol metabolite, cholestanone, was positively correlated with dietary fibre (r = 0.27; P < 0.04). Multiplying faecal progestogen concentration by the cholestanone g−1 dry faeces concentration increased the correlation between serum and cholestanone-indexed faecal progestogens (r = 0.78, P = 0.0001) compared with nonindexed progestogens (r = 0.71, P = 0.0001). We conclude that expressing faecal progestogens g−1 dry faeces may be sufficient and the most cost-effective method for controlling for most dietary effects when the objective is monitoring longitudinal endocrine status in baboons. However, it may be appropriate to express faecal progestogens by cholestanone concentrations when increased precision is needed to overcome the effects of profound variations in dietary fibre.

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Adam J Watkins, Emma S Lucas, Stephanie Marfy-Smith, Nicola Bates, Susan J Kimber and Tom P Fleming

Mammalian placentation is dependent upon the action of trophoblast cells at the time of implantation. Appropriate fetal growth, regulated by maternal nutrition and nutrient transport across the placenta, is a critical factor for adult offspring long-term health. We have demonstrated that a mouse maternal low-protein diet (LPD) fed exclusively during preimplantation development (Emb-LPD) increases offspring growth but programmes adult cardiovascular and metabolic disease. In this study, we investigate the impact of maternal nutrition on post-implantation trophoblast phenotype and fetal growth. Ectoplacental cone explants were isolated at day 8 of gestation from female mice fed either normal protein diet (NPD: 18% casein), LPD (9% casein) or Emb-LPD and cultured in vitro. We observed enhanced spreading and cell division within proliferative and secondary trophoblast giant cells (TGCs) emerging from explants isolated from LPD-fed females when compared with NPD and Emb-LPD explants after 24 and 48 h. Moreover, both LPD and Emb-LPD explants showed substantial expansion of TGC area during 24–48 h, not observed in NPD. No difference in invasive capacity was observed between treatments using Matrigel transwell migration assays. At day 17 of gestation, LPD- and Emb-LPD-fed conceptuses displayed smaller placentas and larger fetuses respectively, resulting in increased fetal:placental ratios in both groups compared with NPD conceptuses. Analysis of placental and yolk sac nutrient signalling within the mammalian target of rapamycin complex 1 pathway revealed similar levels of total and phosphorylated downstream targets across groups. These data demonstrate that early post-implantation embryos modify trophoblast phenotype to regulate fetal growth under conditions of poor maternal nutrition.

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EA Martinez, JM Vazquez, J Roca, X Lucas, MA Gil, I Parrilla, JL Vazquez and BN Day

A 100-fold reduction of the standard dose for artificial insemination in pigs (3 x 10(9) spermatozoa in 80-100 ml fluid) can be used when spermatozoa are deposited surgically next to the uterotubal junction. The present study was performed to develop a technique for non-surgical deep intrauterine insemination in pigs without sedation of the animal. In Expt 1, sows were weaned, treated to induce oestrus and used to evaluate the difficulties involved in the insertion of a flexible fibre optic endoscope through the cervix and along the uterine horn. Deep uterine catheterizations were performed on each sow at 30-40 h after hCG treatment in the crate in which the animal was housed. The endoscope was inserted through an artificial insemination spirette, moved through the cervical canal and propelled forward along one uterine horn until the entire endoscope was inserted. In 30 sows (90.9%) no or minor difficulties were observed during insertion and in these animals the procedure was completed in 4.1 +/- 0.26 min. Insertion of the endoscope through the cervical canal was not possible in only one sow (3.03%). In Expt 2, endoscopic deep intrauterine insemination at 36 h after hCG treatment was performed in 15, 18 and 13 sows with 100, 20 or 5 x 10(7) spermatozoa, respectively, resulting in farrowing rates of 86.6%, 88.9% and 92.3%, respectively; there were no significant differences among groups. Farrowing rates after deep intrauterine inseminations were also not different from those achieved after standard intracervical insemination with 3 x 10(9) spermatozoa (control group: n = 48; 87.5%). Mean litter size (9.41 +/- 0.38 to 10.02 +/- 0.25) was also similar among the different experimental and control groups. In conclusion, endoscopic non-surgical deep intrauterine inseminations can be performed quickly in sows, and normal farrowing rates and litter sizes can be obtained after insemination with a small number of spermatozoa.

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EA Martinez, JM Vazquez, J Roca, X Lucas, MA Gil, I Parrilla, JL Vazquez and BN Day

A fibreoptic endoscope procedure for non-surgical deep intrauterine insemination in non-sedated sows has been reported. However, the endoscope is an expensive and fragile instrument, and is unsuitable for use under field conditions. The aim of this study was to determine the minimum number of spermatozoa required to maintain optimal fertility using a flexible catheter (1.8 m in length, 4 mm in diameter) for deep intrauterine insemination in 2-6 parity non-sedated sows. Crossbred sows were treated with eCG 24 h after weaning and with hCG 72 h later to induce oestrus. Deep intrauterine insemination was performed 36 h after hCG treatment in 117, 126, 60 and 69 sows with 15.0, 5.0, 2.5 or 1.0 x 10(7) spermatozoa in 10 ml, respectively. Weaned sows (n = 147) not treated with hormones and used for standard artificial insemination (AI) (two inseminations per oestrus with 3 x 10(9) spermatozoa in 100 ml) served as controls. The flexible catheter was passed successfully through the cervix into one uterine horn in 95.4% of the sows in an average of 3.7 +/- 0.09 min. Farrowing rates after deep intrauterine insemination with 15 or 5 x 10(7) spermatozoa did not differ from those of the control group (82.9, 76.2 and 83.0%, respectively), but a significant decrease (P < 0.001) was observed in sows inseminated with 2.5 or 1.0 x 10(7) spermatozoa (46.7 and 39.1%, respectively). In contrast, the number of spermatozoa inseminated did not affect prolificacy. Laparotomy revealed that the tip of the flexible catheter reached approximately the anterior third of the uterine horn. Although deep intrauterine insemination was performed in only one uterine horn, the percentages of embryos collected from the tip of both uterine horns 2 days after deep insemination were not significantly different. The results show that in comparison with standard AI, a 20-60-fold reduction in the number of spermatozoa inseminated and an 8-10-fold reduction in the dose volume can be achieved without decreasing fertility when semen is deposited non-surgically into the upper first third of one uterine horn.

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J. C. Lucas, M. B. Renfree, G. Shaw and C. M. Butler

The development of the prostate and the normal descent of the testes in the tammar wallaby (Macropus eugenii) were influenced by treatment with the non-steroidal anti-androgen flutamide. Male pouch young were treated daily from day 9 to day 45, or from day 20 to day 45, of pouch life. Prostate development was inhibited in both treatment groups to a similar extent. Since prostatic buds do not form until day 25 of pouch life, these results suggest that there is a window of androgen sensitivity operating between day 20 and day 25 of pouch life. The number of prostatic buds was significantly lower, but despite the duration of treatment there was never complete abolition of prostate development. Although testes had descended to the same position in treated and control pouch young, inguinal hernias developed in three of four animals treated with flutamide from day 9. These data demonstrate that virilization of the male reproductive tract in this marsupial is dependent on a relatively brief exposure to androgens. Blocking androgen receptor action interferes with normal development of the inguinal canal, which suggests that it is this aspect of inguinoscrotal testicular descent that is androgen dependent.

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Emma S Lucas, Nigel P Dyer, Katherine Fishwick, Sascha Ott and Jan J Brosens

Endometrial stem-like cells, including mesenchymal stem cells (MSCs) and epithelial progenitor cells, are essential for cyclic regeneration of the endometrium following menstrual shedding. Emerging evidence indicates that endometrial MSCs (eMSCs) constitute a dynamic population of cells that enables the endometrium to adapt in response to a failed pregnancy. Recurrent miscarriage is associated with relative depletion of endometrial eMSCs, which not only curtails the intrinsic ability of the endometrium to adapt to reproductive failure but also compromises endometrial decidualization, an obligatory transformation process for embryo implantation. These novel findings should pave the way for more effective screening of women at risk of pregnancy failure before conception.