L-carnitine is a potent antioxidant used for in vitro culture systems. Controversial results have been reported using l-carnitine in culture medium at different stages of in vitro bovine embryo production. Cumulus-oocyte complexes (n = 843) were in vitro-fertilized and cultured and added (treatment group) or not added (control group) with l-carnitine. At day three of culture, each group was subdivided into two subgroups receiving no l-carnitine (group 1), 3.8 mM l-carnitine added during in vitro maturation (group 2), 1.5 mM added during the in vitro culture (group 3), and 3.8 mM and 1.5 mM added during the maturation and culture, respectively (group 4). At day 8, blastocyst embryos were examined for mitochondrial activity, the presence of lipid droplets, total cell number, gene expression, and cryotolerance by vitrification. The data were analyzed with a one-way analysis of variance. l-carnitine added in the late in vitro culture significantly reduced mitochondrial activity and lipid content, and upregulated ifn-τ and ptgs2 gene expression compared to controls (p < 0.05). l-carnitine supplementation did not significantly affect the embryo rate production or survival rate after vitrification and warming (p > 0.05). l-carnitine supplementation significantly improved embryo potential to develop viable pregnancies in agreement with a study reporting improved pregnancy rates.

Early embryo development is driven first by the maternal RNAs and proteins accumulated during the oocyte’s cytoplasmic maturation and then after the embryo genome activation. In mammalian cells, ATP generation occurs via oxidative pathways or by glycolysis, whereas in embryonic stem cells, the consumption of glucose, pyruvate, lipids, and amino acids results in ATP synthesis. Although the bovine embryo has energy reserves in glycogen and lipids, the glycogen concentration is deficient. Conversely, lipids represent the most abundant energy reservoir of bovine embryos, where lipid droplets-containing triacylglycerols are the main fatty acid stores. Oocytes of many mammalian species contain comparatively high amounts of lipids stored as droplets in the ooplasm. L-carnitine has been described as a cofactor that facilitates the mobilization of fatty acids present in the oocyte’s cytoplasm into the mitochondria to facilitate β-oxidation processes. However, the L-carnitine effects by addition to media in the in vitro produced embryos on the quality are highly disputed and contradictory by different researchers. This review’s objective was to explore the effect that the addition of L-carnitine on culture media could have on the overall bovine embryo production in vitro, from the oocyte metabolism to the modulation of gene expression in the developing embryos.

Objetivo. Estimar la diversidad morfométrica, faneróptica y de cuatro genes dominantes en aves criollas de pescuezo desnudo (Gallus domesticus L. Subespecie nudicollis) de traspatio en la subregión Sabana, departamento de Sucre (Colombia). Materiales y métodos. En 650 aves adultas (480 gallinas y 170 gallos) de 10 localidades, se midieron 14 variables morfométricas, ocho fanerópticas y cuatro genes dominantes. Los datos fueron sometidos a análisis descriptivos. Mediante análsis de varianza y test de Ducan se compararon las aves entre localidades. Se evaluó la armonía morfoestructural a partir de las correlaciones entre las mediciones. Se estimaron las frecuencias de los genes Frizzled feather, silky feather, ptilopody y polydactyly, e influencia, sobre cuatro variables mofométricas. Las variables fanerópticas se evaluaron mediante frecuencias. Resultados. Los descriptores analizados mostraron superioridad de los gallos sobre las gallinas al igual que entre localidades (p< 0.001). El peso corporal y longitud del tarso, fueron diferenciadores sexuales (p< 0.001). Las frecuencias alélicas estimadas fueron bajas excepto para el gen Polydactyly, cuyas aves fueron significativamente más grandes (p< 0.001). Las características fanerópticas, describen un ave de plumaje normal, de color marrón, tarsos blancos, color de lóbulo rojo y ojo rojo-naranja, de cresta simple y tamaño pequeño-mediano en gallinas y mediano-grande en gallos. Conclusiones. Se encontró una población heterogénea con gran variabilidad fanerópticas, hay indicios de introgresión de razas especializadas. Las frecuencias de los genes dominantes fueron bajas, con mayor rendimiento para las características W, LC, PT, LP y LA en las aves con genotipo polydactyly.