Luteolytic efficiency of reduced doses of cloprostenol in the ewe. Effect of progesterone concentrations at the time of treatment.

Seventy six ewes were treated with 7.5, 12.5, 25 or 50µg of cloprostenol on day 6 or 9 post-estrus to compare the luteolytic efficiency of the PGF2α analogue at each stage and to evaluate if progesterone concentrations at the time of treatment affect such efficiency. Blood samples were obtained before cloprostenol administration and 12, 24, 48, and 72h thereafter. There was an effect of dose (p<0.05) but not of day post-estrus on the proportion of animals completing luteolysis. As the dose increased, the proportion of ewes completing luteolysis also increased. Also, as the dose increased from 7.5 to 25µg, more ewes showed a transient progesterone decline instead of an absence of response, indicating that in some ewes reduced doses initiated luteolysis but were not able to finish the process. Since the dose of 25µg resulted in close to 50% luteolytic efficacy, this group was used to study the effects of progesterone concentrations at the time of treatment on the response to cloprostenol. Pre-treatment progesterone concentrations were higher (p<0.01) in ewes experiencing luteolytic failure than in those that completed luteolysis. There was a negative correlation between initial progesterone concentrations and their reduction by 12h post-treatment. It is concluded that high progesterone concentrations are associated with a reduction in sensitivity to small doses of cloprostenol. Possible mechanisms and implications of this luteoprotective effect are discussed.

Enfermedad de rosai-dorfman / Rosai-dorfman disease

La enfermedad de Rosai-Dorfman, o sinuhistiocitosis con linfadenopatía masiva, es una rara patología que se presenta con linfadenopatía dolorosa generalizada, más frecuentemente en cabeza y cuello. Su curso clínico y tratamiento es variable. Se describe el caso de un paciente masculino con compromiso nasal de la enfermedad...

Rosai-Dorfman disease, or sinus histiocytosis with massive lymphadenopathy, is a rare disorder presented as painless bilateral lymph node enlargement mainly in the head and neck region. Clinical course and treatment regimen are variable. We described one male patient with nasal involment...

Actividad reproductiva de la oveja Pelibuey durante la época del anestro: Influencia de la presencia del macho / Reproductive Activity of Pelibuey Ewe During the Anoestrus Season: Influence of the Male Presence

Se determinó la actividad reproductiva de ovejas Pelibuey durante la época de anestro, a 19° latitud norte. Se utilizaron 26 ovejas Pelibuey adultas y 21 ovejas nulíparas, hijas de las anteriores. Durante el primer año las ovejas adultas y nulíparas fueron sometidas diariamente a la detección de celos, de diciembre a julio, utilizando machos Pelibuey provistos de mandil. Durante el segundo año, las hembras fueron aisladas de los machos y se determinó la actividad ovárica por medio de concentraciones de progesterona en los mismos meses. En el primer año, la proporción de estros encontrada de enero a abril fue mayor (P < 0,05) en las ovejas adultas (100; 96,1; 84,6 y 96,1%) que en las nulíparas (42,8; 57,1; 52,3; 61,9%), respectivamente. Diez ovejas adultas y cuatro nulíparas ciclaron de manera regular y continua durante todo el período de observación. Durante el segundo año, la actividad ovulatoria se comportó en forma diferente en ambos grupos; a partir de marzo, se muestra un descenso el cual se mantiene hasta junio en las adultas y en julio en las nulíparas. Además, los porcentajes fueron significativamente diferentes. Ocho ovejas adultas tuvieron actividad ovulatoria continua. Se concluye que algunas ovejas Pelibuey tienen capacidad para mostrar actividad reproductiva continua durante los meses del anestro. Dicha actividad es menor en las hembras nulíparas que en las adultas. La presencia del macho durante la detección de celos ejerce un efecto estimulatorio sobre la actividad estral. La identificación de ovejas con capacidad para ciclar en forma continua, abre la posibilidad de realizar un programa de selección tendente a fijar esta característica.

Reproductive activity of Pelibuey ewes during the anoestrus was determined at 19° lat.N. Twenty six adult Pelibuey ewes and their twenty one nuliparous daughters were used. During the first year, adult and nuliparous ewes were subjected to daily estrous detection from December to July with Pelibuey rams fitted with an apron. During the second year, females were isolated from males and ovarian activity was followed by progesterone concentrations for the same months. Monthly estrous proportion from January to April was higher (P < 0.05) in adult (100, 96.1, 84.6 y 96.1%) than in nuliparous ewes (42.8, 57.1, 52.3, 61.9%). In the first year, ten adult and four nuliparous ewes cycled in a regular and continuous manner during the whole observation period. During the second year, ovulatory activity showed different paterns in the experimental groups; following March, there was a percentage reduction up to June (adults) and July (nuliparous). Eigth adult ewes showed a continuos ovulatory activity. It is concluded that some Pelibuey ewes have the capacity to show a continuous reproductive activity during the anoestrus months. This capacity is lower in nuliparous than in adult ewes. The presence of the male during estrous detection exerts an stimulatory effect on estrous activity. Identification of ewes that cycle in an continuous manner open the possibility to establish a selection program toward this trait.