The effect of neutral detergent-soluble fiber level on gut barrier function and intestinal microbiota was examined in weaned rabbits. A control diet (AH) containing 103 g of neutral detergent-soluble fiber/ kg of DM included alfalfa hay as main source of fiber. Another diet (B-AP) was formulated by replacing half of the alfalfa hay with a mixture of beet and apple pulp resulting in 131 g of soluble fiber/kg of DM. A third diet (OH) was obtained by substituting half of the alfalfa hay with a mix of oat hulls and a soybean protein concentrate and contained 79 g of soluble fiber/kg of DM. Rabbits weaned at 25 d and slaughtered at 35 d were used to determine ileal digestibility, jejunal morphology, sucrase activity, lamina propria lymphocytes, and intestinal microbiota. Suckling 35-d-old rabbits were used to assess mucosa morphology. Mortality (from weaning to 63 d of age) was also determined. Villous height of the jejunal mucosa increased with soluble fiber (P = 0.001). Rabbits fed with the greatest level of soluble fiber (BA-P diet) showed the highest villous height/ crypt depth ratio (8.14; P = 0.001), sucrase specific activity (8,671 mumol of glucose/g of protein; P = 0.019), and the greatest ileal starch digestibility (96.8%; P = 0.002). The opposite effects were observed in rabbits fed decreased levels of soluble fiber (AH and OH diets; 4.70, 5,848 mumol of glucose/g of protein, as average, respectively). The lowest ileal starch digestibility was detected for animals fed OH diet (93.2%). Suckling rabbits of the same age showed a lower villous height/crypt depth ratio (6.70) compared with the B-AP diet group, but this ratio was higher than the AH or OH diet groups. Lower levels of soluble fiber tended (P = 0.074) to increase the cellular immune response (CD8+ lymphocytes). Diet affected IL-2 production (CD25+, P = 0.029; CD5+CD25+, P = 0.057), with no clear relationship between soluble fiber and IL-2. The intestinal microbiota biodiversity was not affected by diets (P >/= 0.38). Rabbits fed the B-AP and AH diets had a reduced cecal frequency of detection compatible with Campylobacter spp. (20.3 vs. 37.8, P = 0.074), and Clostridium perfringens (4.3 vs. 17.6%, P = 0.047), compared with the OH diet group. Moreover, the mortality rates decreased from 14.4 (OH diet) to 5.1% (B-AP diet) with the increased presence of soluble fiber in the diet. In conclusion, increased levels of dietary soluble fiber improve mucosal integrity and functionality.

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The effects of different combinations of epidermal growth factor (EGF) and insulin-like growth factor I (IGF-I) on cumulus expansion and meiotic maturation were examined in rabbit oocytes. Selected rabbit follicular oocytes were matured in vitro and were classified as cumulus-oocyte complexes or denuded oocytes. They were cultured in TCM 199, and were treated with growth factors at different concentrations: EGF at 0, 1, 10, 50 and 100 ng ml-1, IGF-I at 0, 50, 100 and 200 ng ml-1 and EGF plus IGF-I at 10 + 50; 10 + 100; 50 + 50 and 50 + 100 ng ml-1, respectively. After 6 h of culture, the oocytes were assessed for nuclear maturation and after 16 h of culture, for cumulus expansion and maturation stage. After culture for 6 h, the incidence of germinal vesicle breakdown was higher (P < 0.05) in all of the growth factor treatments tested compared with controls. After culture for 16 h, EGF enhanced the incidence of cumulus expansion at all of the concentrations tested. Cumulus expansion was greatest with 50 mg EGF ml-1 plus 100 ng IGF-I ml-1 (72.0% versus 2.4% in controls). Treatment with IGF-I significantly increased (P < 0.05) the incidence of metaphase II stage, and maximum stimulation occurred at 100 ng IGF-I ml-1 (84.5% versus 31.1% in controls). However, IGF-I did not affect cumulus expansion. When denuded oocytes were used, no positive effects on nuclear maturation rates were observed for any treatment. These results suggest that: (1) EGF, either alone or with IGF-I, stimulates cumulus expansion; (2) the addition of IGF-I or EGF plus IGF-I significantly enhances nuclear maturation in immature rabbit oocytes; and (3) this effect is mediated by the presence of cumulus cells.

The correlations between chemical composition and coefficient of standardized ileal digestibility (CSID) of crude protein (CP) and amino acids (AA) were determined in 22 soybean meal (SBM) samples originated from USA (n = 8), Brazil (BRA; n = l) and Argentina (ARG; n = l) in 21-day oíd broilers. Birds were fed a commercial maize-SBM diet from 1 to 17 days of age followed by the experimental diets in which the SBM tested was the only source of protein (205g CP/kg) for three days. Also, in vitro nitrogen (N) digestión study was conducted with these samples using the two-step enzymatic method. The coefficient of apparent ileal digestibility (CAID) of the SBM, independent of the origin, varied from 0.820 to 0.880 for CP, 0.850 to 0.905 for lysine (Lys), 0.859 to 0.907 for methionine (Met) and 0.664 to 0.750 for cysteine (Cys). The corresponding CSID valúes varied from 0.850 to 0.966 for CP, 0.891 to 0.940 for Lys, 0.931 to 0.970 for Met and 0.786 to 0.855 for Cys. The CSID of CP and Lys of the SBM were positively correlated with CP (r = 0.514; P<0.05 and r=0.370; P = 0.09, respectively), KOH solubility (KOH sol.) (r=0.696; P<0.001 and r = 0.619; P < 0.01, respectively), trypsin inhibitor activity (TÍA) (r = 0.541; P < 0.01 and r=0.416; P = 0.05, respectively) and reactive Lys (r=0.563; P<0.01 and r=0.486; P<0.05) valúes, but no relation was observed with neutral detergent fiber and oligosaccharide contení. No relation between the CSID of CP determined in vivo and N digestibility determined in vitro was found. The CSID of most key AA were higher for the USA and the BRA meáis than for the ARG meáis. For Lys, the CSID was 0.921,0.919 and 0.908 (P< 0.05) and for Cys 0.828, 0.833 and 0.800 (P< 0.01) for USA, BRA and ARG meáis, respectively. It is concluded that under the conditions of this experiment, the CSID of CP and Lys increased with CP content, KOH sol., TÍA and reactive Lys valúes of the SBM. The CSID of most limiting AA, including Lys and Cys, were higher for USA and BRA meáis than for ARG meáis.

In vivo-matured cumulus-oocyte complexes are valuable models in which to assess potential biomarkers of rabbit oocyte quality that contribute to enhanced IVM systems. In the present study we compared some gene markers of oocytes and cumulus cells (CCs) from immature, in vivo-matured and IVM oocytes. Moreover, apoptosis in CCs, nuclear maturation, mitochondrial reallocation and the developmental potential of oocytes after IVF were assessed. In relation to cumulus expansion, gene expression of gap junction protein, alpha 1, 43 kDa (Gja1) and prostaglandin-endoperoxide synthase 2 (Ptgs2) was significantly lower in CCs after in vivo maturation than IVM. In addition, there were differences in gene expression after in vivo maturation versus IVM in both oocytes and CCs for genes related to cell cycle regulation and apoptosis (V-Akt murine thymoma viral oncogene homologue 1 (Akt1), tumour protein 53 (Tp53), caspase 3, apoptosis-related cysteine protease (Casp3)), oxidative response (superoxide dismutase 2, mitochondrial (Sod2)) and metabolism (glucose-6-phosphate dehydrogenase (G6pd), glyceraldehyde-3-phosphate dehydrogenase (Gapdh)). In vivo-matured CCs had a lower apoptosis rate than IVM and immature CCs. Meiotic progression, mitochondrial migration to the periphery and developmental competence were higher for in vivo-matured than IVM oocytes. In conclusion, differences in oocyte developmental capacity after IVM or in vivo maturation are accompanied by significant changes in transcript abundance in oocytes and their surrounding CCs, meiotic rate, mitochondrial distribution and apoptotic index. Some of the genes investigated, such as Gja1, could be potential biomarkers for oocyte developmental competence in the rabbit model, helping improve in vitro culture systems in these species.