Local influence of the corpus luteum on the ipsilateral oviduct and early embryo development in the ewe.

The objective of this study was to evaluate the local effect of the corpus luteum (CL) on ipsilateral oviduct-uterus functionality and early embryo development in ewes. A total of 499 embryos were transferred on Day 1 after in vitro fertilization into the ipsilateral (n = 250) and contralateral oviducts (n = 249) of 13 ewes on Day 1 after ovulation (18-20 embryos per oviduct). On Day 6, their reproductive tracts were collected and their uterine horns were flushed for embryo recovery. More recovered embryos, a higher proportion of blastocysts, and more viable embryos were collected when the embryos were transferred into the ipsilateral oviducts (P < 0.05). In addition, almost five times higher P4 concentrations and significantly lower E2 concentrations, with higher P4:E2 ratio, were found in the ipsilateral than contralateral oviductal tissue (P < 0.05). Furthermore, a higher concentration of adiponectin was found in the ipsilateral uterine tissue macerates than in the contralateral side to the CL. The ipsilateral oviductal tissue had a lower expression of PGR and IGFBP5, but the transcript expression of ADIPOR1 was higher in the ipsilateral oviductal tissue. In the uterus, the mRNA expression of ESR1, IGFBP3, IGFBP5, and LEPR was higher or tended to be higher in the ipsilateral than contralateral uterine tissue. Uterine flushing fluid collected from the ipsilateral uterine horn had lower insulin concentrations than the contralateral horn, while no differences were found in the P4 and E2 concentrations. In conclusion, on Day 6 post-ovulation, P4 was elevated in the ipsilateral oviductal tissue, embryo development was advanced, and differential gene expression of PGR, ESR1, IGFBP3, IGFBP5, LEPR, and ADIPOR1 in the oviductal or uterine tissue was found between the ipsilateral and contralateral side. This study demonstrates local regulation of the ovary on the ipsilateral oviduct/uterine horn in the ewe.

Genetic parameters of objectionable fibers and of their associations with fleece traits in Corriedale sheep.

The aim of this research was to assess the variability and genetic relationships among binary traits denoting the presence or absence of objectionable fibers, namely pigmented (BINPPF), medullated (BINPMED), and kemp fibers (BINPK), and of fleece traits (fiber diameter [FD] and clean fleece weight [CFW]) in Corriedale sheep. Additionally, the total response to selection against objectionable fibers and indirect responses when selecting for fleece traits were evaluated. Fiber records from 679 animals and fleece records from 795 animals obtained from 2 experimental flocks (from 2005 to 2007) were used; the pedigree file included a total of 3,792 animals. Heritability and genetic correlations among the traits were estimated with a multivariate animal model under a Bayesian setting. Heritability estimates (posterior SD) for BINPPF, BINPMED, and BINPK were 0.35 (0.08), 0.37 (0.10), and 0.63 (0.09), respectively; for CFW and FD, estimates were 0.42 (0.09) and 0.43 (0.08), respectively. The genetic correlations between CFW and the 3 types of objectionable fibers were very low (i.e., <0.2). Thus selection for CFW is not expected to affect the number of such fibers in any direction. The same occurred for the genetic correlation between BINPK and FD. Genetic correlations between FD and BINPMED and FD and BINPPF were positive and favorable (0.50 and 0.56, respectively). Selecting for lower FD would decrease the numbers of objectionable fibers. The expected correlated responses in BINPPF, BINPMED, and BINPK when selecting for CFW were -0.03 (0.11), 0.03 (0.11), and -0.05 (0.18), respectively; when selecting for FD, the correlated responses were -0.26 (0.11), -0.26 (0.11), and -0.14 (0.16). Overall, this study reports novel information on genetic parameters for the presence of objectionable fibers and their associations with fleece traits in sheep. Our findings suggest that it could be possible to improve FD while at the same time reducing the content of BINPMED and BINPPF in wool; however, improvements in CFW are likely to have no effect on the numbers of objectionable fibers.