SPATIO-TEMPORAL VARIATIONS OF MACRO AND TRACE MINERAL CONTENTS IN SIX NATIVE PLANTS CONSUMED BY SMALL RUMINANTS AT NORTHEASTERN MEXICO

During two consecutive years the Ca, K, Mg, Na, P, Cu, Fe, Mn and Zn contents were determined, seasonally, in foliar tissue of native trees (T) and shrubs (S) from northeastern Mexico such as Acacia rigidula (S), Bumelia celastrina (T), Croton cortesianus (S), Karwinskia humboldtiana (S), Leucophyllum frutescens (S) and Prosopis laevigata (T). Collections were carried out from August 2004 to May 2006 in a subtropical and semiarid region of the State of Nuevo Leon, Mexico at three county (Los Ramones, China and Linares) sites, which are grouped under a similar climatic pattern. Mineral concentrations were quantified using an atomic absorption spectrophotometer, with exception of P content that was estimated using a colorimeter. Mineral data were statistically analyzed using one-way analysis of variance with a multi-factorial arrangement being years (2), sites (3), seasons (4), and plant species (6) the factors. All minerals in all plants were significantly different among years, sites and seasons; however, some interactions were not significant. In general, plants in Linares site had higher mineral content followed by Los Ramores and China; in addition, during the year two, all plants had higher mineral content; moreover, during summer all plants had higher mineral content followed by fall, spring and winter. Yearly and seasonal variations in plant minerals might have been related to seasonal water deficits, excessive irradiance levels during summer and extreme low temperatures in winter that could have affected leaf development and senescence. In spite of these differences, all plant species had suitable levels of Ca, Mg, K, Fe and Mn to satisfy grazing ruminant requirements. However, P, Na, Zn and Cu, showed marginal inadequate concentrations in prolonged periods throughout the year and it might have a negative impact on animal productivity

CONTROL DE LA ACTIVIDAD SEXUAL DE LOS CAPRINOS SIN HORMONAS EXÓGENAS: USO DEL FOTOPERIODO, LAS RELACIONES SOCIO-SEXUALES Y LA NUTRICIÓN

Algunas razas caprinas de las latitudes subtropicales muestran una muy marcada estacionalidad de su actividad sexual anual, mientras que otras sólo presentan una moderada estacionalidad sexual. La estacionalidad sexual provoca el problema de que la producción de leche, queso y cabrito sea también estacional. Para resolver este problema, es necesario tener un profundo conocimiento de las características sexuales de estos animales e identificar el factor del medio ambiente que controla su ciclo anual de reproducción. En este artículo describiremos las reflexiones que nos permitieron desarrollar técnicas sustentables de control reproductivo de los caprinos del subtrópico mexicano. Primero, determinamos las características del ciclo anual de actividad sexual de los machos y hembras caprinos. Segundo, identificamos que el fotoperiodo era el principal factor del medio ambiente que regula el ciclo sexual anual de ambos sexos.  Tercero, utilizamos el fotoperiodo para estimular la actividad sexual de los machos durante el periodo de reposo. Posteriormente, los machos cabríos sexualmente activos se utilizaron para inducir y sincronizar la actividad estral y ovulatoria de las cabras anéstricas mantenidas en condiciones extensivas o intensivas, a través de la técnica de bioestimulación conocida como efecto macho. Finalmente, determinamos que la complementación alimenticia mejora la respuesta reproductiva de las cabras expuestas a los machos cabríos. Estos resultados constituyen una manera original para controlar la actividad sexual de los caprinos utilizando el fotoperiodo, el efecto macho y la nutrición

SENSORIAL AND PHYSIOLOGICAL CONTROL OF MATERNAL BEHAVIOR IN SMALL RUMINANTS: SHEEP AND GOATS

Contrary to rodents in which maternal behaviors is characterized by the nest formation and give birth to altricial offsprings, maternal behavior in sheep and goats is characterized by the establishment of a selective bond between the mother and their progeny during the first postpartum hours. In both species, maternal behavior ethogram at parturition consists of a series of behaviors that initiates with the prepartum isolation of the female from their coespecifics and that culminates with the successful exclusive nursing behavior toward their newborn during postpartum. The sensory and physiological factors that control the expression of maternal behavior are very similar in both sheep and goats, although in the goats there is little information generated about this aspect. The increased peripherical concentrations of oestradiol at the end of gestation and the vaginocervical stimulation are two primary physiological events that are very important to the expression of the maternal behavior. However, olfactory cues from the offspring also are involved in the maintenance of maternal responsiveness once the birth takes place. Although mother-young spatial relationships during postpartum are different between sheep (followers) and goats (hiders) the maternal behavior had many similarities and their sensorial and physiological control are basically identical for many aspects