Resumen El objetivo fue evaluar los pastos del género Urochloa: Mulato II, Convert 330 y Convert 431 al variar las edades de corte en los atributos: dinámica de población de tallos, recambio de tejido, relación hoja:tallo, peso por tallo y rendimiento de materia seca. La investigación se realizó en las praderas del Instituto Tecnológico de Pinotepa, en la localidad de San José Estancia Grande, Oaxaca. Los tratamientos fueron los genotipos: Mulato II, Convert 330 y Convert 431. Los datos se analizaron mediante un diseño de bloques completamente al azar con arreglo en parcelas divididas y cuatro repeticiones, el procedimiento utilizado fue PROC GLM de SAS. El pasto Mulato II presentó mayor densidad de tallos con un promedio de 540 tallos m-2, mientras que el pasto Convert 330 registró la menor densidad de tallos a lo largo de la investigación, con un promedio de 220 tallos m-2, tendiendo a aumentar más lento en el tiempo (p< 0.05). El pasto que obtuvo el mayor crecimiento neto fue Convert 330 seguido por Mulato II y al final Convert 431 con un promedio de 169, 133 y 104 cm tallo-1, respectivamente ((p< 0.05). El pasto Convert 330 en el día 49 después del corte obtuvo el mayor rendimiento con 4 091 kg MS ha-1 (p< 0.05). Como conclusión el genotipo Convert 330 presento mejores características estructurales en la pradera lo que refleja mayor rendimiento de materia seca.

Abstract The objective was to evaluate the grasses of the genus Urochloa: Mulato II, Convert 330 and Convert 431 by varying the cut ages in the attributes: stem population dynamics, tissue replacement, leaf:stem ratio, weight per stem and dry matter yield. The research was carried out in the grasslands of the Technological Institute of Pinotepa, in the locality of San José Estancia Grande, Oaxaca. The treatments were the genotypes: Mulato II, Convert 330 and Convert 431. The data were analyzed using a completely randomized block design arranged in split plots and four repetitions, the procedure used was PROC GLM of SAS. The Mulato II grass had the highest stem density with an average of 540 stems m-2, while the Convert 330 grass had the lowest stem density throughout the research, with an average of 220 stems m-2, tending to increase slower over time (p< 0.05). The grass that obtained the highest net growth was Convert 330, followed by Mulato II and, at the end, Convert 431, with an average of 169, 133 and 104 cm stem-1, respectively (p< 0.05). On day 49 after cutting, the Convert 330 grass obtained the highest yield with 4 091 kg DM ha-1 (p< 0.05). In conclusion, the Convert 330 genotype showed better structural characteristics in the grassland, which reflects a higher dry matter yield.

Resumen El objetivo fue analizar la relación entre el perfil de resistencia a antibióticos y la formación de biofilm de aislados de S. aureus provenientes de mastitis bovina. Se analizaron 30 aislados de S. aureus procedentes de casos de mastitis subclínica en granjas lecheras en sistemas de producción semi-intensivo y de traspatio ubicadas en los estados de Guanajuato y Michoacán, México. Se realizó un antibiograma por el método de difusión en disco Kirbi Bauer. La formación de biofilm se determinó por el método de tinción con cristal violeta. Para la evaluación de genes de resistencia a antibióticos y de formación de biofilm se obtuvo ADN genómico de una colonia para la identificación de los genes: blaZ, mecA, tetK, tetM, gyrA y gyrB, y icaA e icaD. Los resultados mostraron que el 100 % de los aislados fueron resistentes a penicilina y dicloxacilina, seguidos por cefotaxima (86.6 %), ampicilina y cefalotina (83.3 %) y ceftazidima (80.0 %), mientras que se observó un 36.6 % de resistencia a oxacilina. Se identificó que todos los aislados de S. aureus presentaron la capacidad de formar biofilm con un rango del 20 a 98 %. Se observó además que los aislados con una multirresistencia elevada presentaron una mayor formación de biofilm; estableciéndose una correlación positiva significativa. En conclusión, los aislados de S. aureus provenientes de mastitis bovina presentaron elevados niveles de resistencia a antibióticos; así como una importante capacidad formadora de biofilm, demostrando la existencia de una correlación positiva entre estos dos factores.

Abstract The objective was to analyze the relationship between the antibiotic-resistance profile and the biofilm formation of S. aureus isolates from bovine mastitis. Thirty (30) isolates of S. aureus from cases of subclinical mastitis in dairy farms in semi-intensive production and backyard production systems, located in the states of Guanajuato and Michoacán, Mexico, were analyzed. An antibiogram was performed by the Kirbi-Bauer disc-diffusion method. Biofilm formation was determined by the violet crystal staining method. For the evaluation of antibiotic resistance genes and biofilm formation, genomic DNA was obtained from a colony for the identification of the genes: blaZ, mecA, tetK, tetM, gyrA and gyrB, and icaA and icaD. The results showed that 100 % of the isolates were resistant to penicillin and dicloxacillin, followed by cefotaxime (86.6 %), ampicillin and cephalotin (83.3 %) and ceftazidime (80.0 %), while a 36.6 % resistance to oxacillin was observed. It was identified that all isolates of S. aureus had the ability to form biofilm with a range between 20 to 98 %. It was also observed that isolates with a high multi-resistance presented a greater formation of biofilm, establishing a significant positive correlation. In conclusion, S. aureus isolates from bovine mastitis presented high levels of antibiotic resistance; as well as an important biofilm-forming capacity, demonstrating the existence of a positive correlation between these two factors.

ABSTRACT Records of 3716 Nubian goats from the United States (US) were analyzed to estimate relationships between fourteen conformation traits (CT) with lactation average somatic cell score (ASCS). To analyze ASCS, a mixed model was implemented. Linear and quadratic effects of CT traits, days in milk (DIM), and kidding age in months (KA) were considered as fixed covariates, and herd-year (HY) of kidding as a random effect. Correlation coefficients between CT traits and ASCS adjusted for HY and linear and quadratic KA effects were also obtained. The average ± standard deviations for ASCS, DIM, and milk yield were 5.17±0.54 Log2, equivalent to 451.3 cells × 103/mL, 266.3±52.1 days, and 776.3±280.4 kg per lactation, respectively. Significant non-linear relationships with an intermediate maximum were found between ASCS with teat diameter and medial suspensory ligament, while linear relationships were observed with stature, strength, rump width, fore udder attachment, udder depth, teat diameter, teat placement, and medial suspensory ligament. The model explained 53.7% of the ASCS variability, but the contribution of each type variable to increase the coefficient of determination was low (<0.52%). Herd-year explained a large proportion of the variation of ASCS (38.4%). All estimated correlations between CT and ASCS had low values, from −0.04 to 0.11, but most were significant. The results of this study show that conformation traits have few opportunities to contribute phenotypically to assess somatic cell score in Nubian goats.