In the first experiment, forage samples (n = 39) were collected during 4 years (2006 ? 2009) from pastures grazed by Santa Gertrudis cattle at the King Ranch, TX. The in vitro gas production technique (IVGP) was performed to understand the pattern of fermentation parameters of the forage and obtain fractional digestion rate (kd) values to predict total digestible nutrients (TDN). The best nonlinear model to describe the IVGP values of the forages was the two-pool logistic equation. The passage rate (kp) of 4%/h was used.. The kp predicted by the Large Nutrient Ruminant System (LNRS) model was 3.66%/h. The average TDN was 55.9% compared to 53.8% using a theoretical equation. In the second experiment, Brahman bulls (n = 16) grazed Coastal bermudagrass pastures [Cynodon dactylon (L.) Pers.] and stocked at a moderate to low grazing pressure. Three periods of fecal collections were made within each period. Bulls were individually fed at 0700 and 1900 h of 400 g of corn gluten pellets containing C32 n-alkanes. Each period was divided in 2 sub periods in which fecal samples were collected 4 times a day (0700, 1100, 1500 and 1900 h). N-alkanes in the forage and feces were determined using gas chromatography. In the third experiment, four methods were used to estimate dry matter intake (DMI): C31 or C33 with or without adjustment for forage C32 (C31_0 and C33_0, respectively). There was a difference between morning (0700 and 1100 h) and afternoon fecal collections (1500 and 1900 h) on the predicted DMI using C31 (P = 0.0010), C33 (P = 0.0001), C31_0 (P = 0.0010), or C33_0 (P < 0.0001). There was no difference in average daily gain (ADG) between low and high residual feed intake (RFI) (P = 0.5709). The nonparametric analysis indicated that preranking animals for efficiency under confinement conditions does not guarantee (P < 0.0001) similar ranking under grazing conditions when using the alkane technique to determine forage DMI. In order to estimate DMI at least 5 d of fecal collection and 2 times a day of collection (0700 and 1500h) are needed to decrease the variability.

Prenatal mortality in the swine ranges from 30%~40%. Little is known about genes that involve in the preovulation events that the initiation of swine oocyte development. The main objective of this study was to utilize suppression subtractive hybridization¡]SSH¡^to delineate the differential gene expression between in vitro culture mature and antral-follicle oocytes of swine development. The knowledge of genes and their accumulated mRNA is essential to better understand the mechanisms involved in the oocyte maturation and the survival of the in vitro produced embryos. Porcine ovaries obtained from the slaughterhouse were used to collect oocytes from follicle with a diameter ≥ 3 mm. After in vitro mature for two days, oocytes with first polar body were subjected to as the testers and were lysed for mRNA extraction. Pools of 26 denuded oocytes without culture were submitted to suppressive subtraction hybridization (SSH) as the drivers. Forward and reverse subtractions were performed to identify candidate genes differentially expressed between in vitro culture mature and primordial-follicle oocytes. A total of one hundred and thirty-five differential expressed plasmid clones were sequenced, and each was analyzed by BLAST programs. Of these transcripts, 40 clones were subjected to differential screening by a dot blot cDNA array. We identified three genes like zona pellucida glycoprotein (ZP1), 1-aminocyclopropane-1-carboxylate synthase (ACS), and death associated protein 5¡]DAP 5¡^while other numerous clones remain novel. The in vivo functions of the genes remain further investigation.

The newly discovered oocyte-derived growth factor BMP15, like GDF9, is a member of the transforming growth factor-£] (TGF-£]) superfamily. To our knowledge, however, the expression and function of BMP15 in ovarian tissues has not yet been studied in the pig. We asked whether the relative abundance (RA) of BMP15 mRNA changes in oocytes and follicular cells during pre-ovulatory period or culture of cumulus-oocyte-complexs (COCs) in vitro. Denuded oocytes, cumulus cells and COCs were isolated from growing and pre-ovulatory follicles. Total RNA was extracted from the cells, and reverse transcriptase polymerase chain (RT-PCR) was carried out using specific oligo-nucleotide primers. Expansion of COCs was firstly observed at 18 h, when this period we found BMP15 mRNA expression obviously. But when we culture of denuded oocytes instead of COCs, BMP15 mRNA didn¡¦t express throughout the period. We also detected GDF9 and BMP15 mRNA in pig embryonic stage and in differentiation stage of pig stem cell. GDF9 mRNA level continued to express after fertilization, but BMP15 mRNA didn¡¦t appear. We also added BMP15 antibody against Expanding of COCs. The present results support the concept that BMP15 is a key mediator of oocyte-enabled cumulus expansion in pig.

An infectious cDNA clone of Vero cell adapted Beaudette strain of IBV was constructed using in vitro assembly of cDNA fragments. The entire genome of IBV was RT-PCR amplified into seven fragments, with each piece overlapping about 10 nucleotides. The fragments were ligated and transcribed to synthesize RNA, which was transfected into BHK-21 cells. These cells were then overlaid onto IBV susceptible Vero cells. After five days transfection, the virus was successfully rescued from the transfected cells. The cDNA clone from our laboratory strain has a five nucleotide insertion not present in the originally sequenced virus, resulting in total genome size of 27,613 nucleotides. The infectious cDNA clone was further manipulated to demonstrate its potential as a gene transfer vector, by replacing the ORF5a open reading frame with enhanced green fluorescent protein. The recombinant infectious cDNA clone was also successfully rescued after three days transfection of BHK-21 cells followed by co-culturing with Vero cells. This study showed that the 5a protein, whose function is not known, is not necessary for in vitro IBV replication. This study also showed that the 5a ORF is a good candidate for an insertion site of recombinant genes for the development of IBV infectious cDNA clone as a gene transfer vector.

Thèse d'exercice : Médecine. Neurologie : Université de Nantes : 2004. / Bibliogr. f. 95-101.

Thèse d'exercice : Médecine. Gynécologie médicale : Nantes : 2007. / Bibliogr.

Thèse d'exercice : Médecine. Gynécologie-obstétrique : Université de Nantes : 2007. / Bibliogr.

Zugl.: Berlin, Freie Universiẗat, Diss., 2009.

Zugl.: Giessen, Univ., Diss., 2009

Zugl.: Giessen, Universiẗat, Habil-Schr., 2009.