RESUMO: Este estudo foi conduzido para avaliar as mudanças em alguns indicadores do estado oxidativo durante a gestação e lactação em ovelhas com diferentes números de partos. Ovelhas Dorset x Sufolk foram classificadas pelo número de partos: 1, 2 e ≥4. Amostras foram coletadas antes da prenhez e no primeiro, segundo, terceiro e quarto mês e no dia 143 de gestação, assim como no dia 5 após o parto e com um mês de lactação. Encontrou-se que a capacidade antioxidativa teve duas reduções, a primeira durante o segundo mês de gestação e a segunda no dia 5 de lactação. A atividade total da glutationa peroxidase aumentou quando se deram as reduções de capacidade antioxidante. O ácido ascórbico diminuiu durante a gestação e lactação, com o valor mais baixo foi no terceiro mês de gestação. Conclui-se que a suscetibilidade a oxidação diminui com o número de partos, e que nas ovelhas durante a gestação e lactação há um mecanismo que previne a oxidação lipídica ocasionando mudanças na capacidade antioxidante, e das atividades glutationa peroxidase e ácido ascórbico.

ABSTRACT: This study was conducted to assess the changes in some indicators of oxidative status during pregnancy and lactation in sheep of different parity. Dorset x Suffolk ewes were classified by number of parity: 1, 2 and ≥4. They were sampled before pregnancy and on the first, second, third, and fourth months, then on day 143 of pregnancy, as well as on day 5 after birth and after one month of lactation. Antioxidant capacity was found to have two reductions, the first during the second month of pregnancy and the second on day 5 of lactation. Susceptibility to lipid oxidation decreased with an increased number of parturitions. A reduction in lipid oxidation was observed on day 143 of gestation relative to the other samplings during gestation and lactation. Total glutathione peroxidase activity increased when the two reductions in antioxidant capacity took place. Ascorbic acid decreased during lactation and gestation; the lowest values were recorded in the third month of gestation. It is concluded that susceptibility to lipid oxidation decreases with the number of parturitions and that in ewes, during gestation and lactation, there is a mechanism that prevents lipid oxidation involving changes in antioxidant capacity, glutathione peroxidase and ascorbic acid.

The aim of this experiment was to study the performance of Orchard grass (Dactylis glomerata L.) based on herbage yield and quality under different grazing management. Three frequencies (2, 3 and 4 wk in spring and summer and 4, 5 and 6 wk in fall) and two grazing intensities (hard: 3 to 5 cm and lax: 6 to 8 cm of residual sward height), in a randomized block design with three replicates, distributed in a 2 x 3 factorial arrangement. Cumulative herbage yield (CHY), net herbage accumulation rate (NHAR), morphological composition and herbage quality were evaluated. The highest CHY and average NHAR were recorded with hard grazing every 4 and 6 wk. The highest seasonal herbage yield (7,844 kg DM ha-1) and NHAR (107 kg DM ha-1 d-1) were observed during summer with hard grazing every 4 wk (P<0.05). There were not statistical differences in herbage yield and NHAR during spring between grazing frequencies. In fall, 5 wk grazing frequency was higher than 4 wk (P<0.05), but it was similar to 6 wk (P>0.05). Across all seasons, hard grazing gave higher forage yield than lax grazing, being different in spring and summer (P<0.05). In overall, total protein and in vitro dry matter digestibility tended to decrease as grazing interval increased, being on average 20 and 65 %, respectively. It was concluded that to obtain the highest herbage yield and quality, orchard grass must be grazed hard every 4 wk in spring-summer and every 5 wk in fall.

El objetivo fue determinar el rendimiento y calidad del pasto ovillo (Dactylis glomerata L.), al variar la frecuencia e intensidad de pastoreo. Se evaluaron tres frecuencias (2, 3 y 4 semanas en primavera y verano y 4, 5 y 6 semanas durante otoño) y dos intensidades de pastoreo (severa: 3 a 5 cm y ligera: 6 a 8 cm de altura de forraje residual). Se evaluó el rendimiento de forraje, tasa de acumulación neta de forraje (TANF), composición morfológica y calidad del forraje. El mayor rendimiento acumulado y TANF se presentaron con pastoreo severo cada 4 y 6 semanas y en ambas intensidades cada 3 y 5 semanas. El mayor rendimiento estacional (7,844; 7,699; 7114 kg MS ha-1) se presentó en verano en las mismas frecuencias e intensidades de pastoreo, respectivamente (P<0.05). Durante primavera no se observaron diferencias en rendimiento y TANF entre frecuencias de pastoreo. En otoño la frecuencia de 5 semanas superó a la de 4 (P<0.05), pero no diferente a la de 6 semanas. En todas las estaciones del año la intensidad de pastoreo severo superó a la ligera, siendo diferentes en primavera y verano (P<0.05). En general, el contenido de proteína total y digestibilidad in vitro de la materia seca tendieron a disminuir conforme aumentó el intervalo de pastoreo, siendo en promedio de 20 y 65 %, respectivamente. Se concluye que para obtener el mayor rendimiento y calidad de forraje, los pastoreos deben realizarse cada 4 semanas durante primavera-verano y cada 5 semanas en otoño, a una intensidad severa.

OBJECTIVE: We present a model for the 2009 influenza epidemic in Mexico to describe the observed pattern of the epidemic from March through the end of August (before the onset of the expected winter epidemic) in terms of the reproduction number and social isolation measures. MATERIAL AND METHODS: The model uses a system of ordinary differential equations. Computer simulations are performed to optimize trajectories as a function of parameters. RESULTS: We report on the theoretical consequences of social isolation using published estimates of the basic reproduction number. The comparison with actual data provides a reasonable good fit. CONCLUSIONS: The pattern of the epidemic outbreak in Mexico is characterized by two peaks resulting from the application of very drastic social isolation measures and other prophylactic measures that lasted for about two weeks. Our model is capable of reproducing the observed pattern.

OBJETIVO: Se presenta un modelo de la epidemia de influenza en México en 2009 para describir el patrón observado desde marzo hasta finales de agosto (antes del inicio de la epidemia invernal), en términos del número reproductivo y las medidas de aislamiento social. MATERIAL Y MÉTODOS: El modelo es un sistema de ecuaciones diferenciales ordinarias. Se realizaron simulaciones computacionales para la optimización de trayectorias como función de los parámetros. RESULTADOS: Se exploran las consecuencias de esta última medida combinada con los valores estimados en la literatura médica del número reproductivo básico. CONCLUSIONES: El patrón de la epidemia mexicana de influenza es bimodal debido a la aplicación del aislamiento social y otras medidas profilácticas que duró aproximadamente dos semanas. Este modelo es capaz de reproducir el patrón observado.

OBJECTIVE: We present a model for the 2009 influenza epidemic in Mexico to describe the observed pattern of the epidemic from March through the end of August (before the onset of the expected winter epidemic) in terms of the reproduction number and social isolation measures. MATERIAL AND METHODS: The model uses a system of ordinary differential equations. Computer simulations are performed to optimize trajectories as a function of parameters. RESULTS: We report on the theoretical consequences of social isolation using published estimates of the basic reproduction number. The comparison with actual data provides a reasonable good fit. CONCLUSIONS: The pattern of the epidemic outbreak in Mexico is characterized by two peaks resulting from the application of very drastic social isolation measures and other prophylactic measures that lasted for about two weeks. Our model is capable of reproducing the observed pattern.

OBJETIVO: Se presenta un modelo de la epidemia de influenza en México en 2009 para describir el patrón observado desde marzo hasta finales de agosto (antes del inicio de la epidemia invernal), en términos del número reproductivo y las medidas de aislamiento social. MATERIAL Y MÉTODOS: El modelo es un sistema de ecuaciones diferenciales ordinarias. Se realizaron simulaciones computacionales para la optimización de trayectorias como función de los parámetros. RESULTADOS: Se exploran las consecuencias de esta última medida combinada con los valores estimados en la literatura médica del número reproductivo básico. CONCLUSIONES: El patrón de la epidemia mexicana de influenza es bimodal debido a la aplicación del aislamiento social y otras medidas profilácticas que duró aproximadamente dos semanas. Este modelo es capaz de reproducir el patrón observado.

The reduction in protein content and inclusion of wheat bran in the diet improves the amino-acids (AA) profile, but increases the fiber content. To this respect, yeasts can increase the digestion of fiber. Three experiments were carried out to evaluate the effect of yeast culture (YC) on diets with a standard (SCPD) or low level of crude protein (LCPD), with or without free AA, for growing-finishing pigs (Landrace-Hampshire-Duroc). In the three experiments the design was randomized complete blocks and data were analyzed with GLM procedure of SAS. In experiment 1, 28 growing pigs (25.2±4.7 kg) were used and there was a factorial arrangement 2 (CP, 11.0 and 18.8 %) x 2 (YC, 0 and 0.75 %) of treatments. The YC did not change (p>0.33) the productive response; the CP level did not influence weight gain (ADG) nor feed intake (FI; p>0.14), but the conversion (CA) was better (p=0.01) with SCPD. Experiment 2 was conducted with 40 finishing pigs (60.2±8.3 kg) and the treatments (T) were: Tl) base diet, wheat-soybean-wheat-bran meal; T2) T1 + 0.75 % of YC; T3) Tl + 1.5 % of YC; T4) control diet wheat-soybean meal; and T5) diet low in CP + free AA. The YC did not change the performance nor the characteristics of the carcass; when it was compared with the LCPD, the area of the longissimus dorsi muscle (p=0.08) and the back fat (p=0.02) were better in pigs fed diets with YC CL, but yield (p=0.02), ADG (p=0.04) and FI (p=0.05) were higher in the LCPD. Experiment 3 was conducted with 32 finishing pigs (67.1 ±10.3 kg); and there was a factorial arrangement 2 (PC, 13.0 and 16.0%) x 2 (YC, 0 and 0.75 %) of treatments. The YC (p>0.70) and the CP level (p≥0.43) did not affect the response of the pigs. It can be concluded that the inclusion of YC in wheat-based diets does not influence the productive response of growing to finishing pigs.

La reducción en el contenido de proteína y la inclusión de salvado de trigo en la dieta mejora el perfil de aminoácidos (AA) pero incrementa el contenido de fibra. Al respecto, los cultivos de levadura pueden aumentar la digestión de la fibra. Por tanto, se realizaron tres experimentos para evaluar el efecto de cultivos de levaduras (CL) en dietas con un nivel de proteína cruda estándar (DEPC) o bajo (DBPC), sin o con AA libres, para cerdos (Landrace-Hampshire-Durc) en crecimiento-finalización. En los tres experimentos el diseño fue de bloques completos al azar y los datos se analizaron con el procedimiento GLM de SAS. En el experimento 1 se usaron 28 cerdos en crecimiento (25.2±4.7 kg), con un arreglo factorial 2 (PC, 11.0 y 18.8 %) x 2 (CL, 0 y 0.75 %) de tratamientos. El CL no cambió (p>0.33) la respuesta productiva; el nivel de PC no influyó en la ganancia ni consumo (p>0.14), pero la conversión (CA) fue mejor (p=0.01) con DEPC. El experimento 2 se realizó con 40 cerdos en finalización (60.2±8.3 kg) y los tratamientos (T) fueron: TI) dieta base, trigo-pasta de soya-salvado de trigo; T2) TI + 0.75 % de CL; T3) TI + 1.5 % de CL; T4) dieta testigo trigo-pasta de soya; y T5) dieta baja en PC + AA libres. El CL no cambió el comportamiento (p>0.34) ni las características de la canal; cuando se comparó con la DBPC, el área del músculo longissimus dorsi (p=0.08) y la grasa dorsal (p=0.02) fueron mejores en cerdos que recibieron CL, pero el rendimiento (p=0.02), la GDP (p=0.04) y el CDA (p=0.05) fueron mayores en la DBPC. El experimento 3 se realizó con 32 cerdos en finalización (67.1 ±10.3 kg); y hubo un arreglo factorial 2 (PC, 13.0 y 16.0 %) x2 (CL, 0 y 0.75 %) de tratamientos. El CL (p>0.70) y el nivel de PC (p≥0.43) no cambiaron la respuesta de los cerdos. Se puede concluir que la inclusión de CL en dietas con base a trigo no influye en la respuesta productiva de cerdos en crecimiento- finalización.