Factors influencing timing of puberty in Mexican gray wolves (Canis lupus baileyi)

The reintroduced population of Mexican gray wolves (Canis lupus baileyi) continues to rely on a carefully managed captive breeding program. Although success of that program depends on detailed knowledge of reproductive processes, age of puberty has not been determined. This study assessed male puberty status (presence of sperm in ejaculates), maintained in nine US facilities, during their first breeding season. Variables possibly associated with puberty were also evaluated. There was a significant effect of body weight, testis size, facility latitude, and date of collection, whereas a statistical trend was found for age and inbreeding coefficient. Social factors, including being housed with sire, had no effect. Over half the males in their first breeding season were producing sperm, although in some cases sperm quality was poor, suggesting possible infertility. Although there was no minimum body weight associated with presence of sperm, likelihood increased with increasing body weight, highlighting a possible critical role for nutrition. The trend for sperm production in males collected later in the breeding season and at lower latitudes suggests that later collections, especially at higher latitudes, might reveal a higher percentage of pubertal males. These results have potential implications for breeding program management and introduce the possibility that more wild gray wolves than previously thought might produce sperm during their first year, even if they do not sire young. La población reintroducida de lobo mexicano (Canis lupus baileyi) depende aún de un programa de reproducción en cautiverio cuidadosamente gestionado. Aunque el éxito del programa depende del conocimiento detallado de los procesos reproductivos, la edad de la pubertad no ha sido determinada. Este estudio evaluó el estado de pubertad de los machos (presencia de espermatozoides en los eyaculados) mantenidos en nueve instituciones de los Estado Unidos, durante su primera temporada reproductiva. También se evaluaron variables asociadas posiblemente con la pubertad. Se encontró un efecto significativo del peso corporal, el tamaño de los testículos, la latitud de la institución y la fecha de recolección; mientras que para la edad y el coeficiente de consanguinidad se encontró una tendencia estadística. Factores sociales, incluyendo estar alojado con el padre, no tuvieron ningún efecto. Más de la mitad de los machos en su primera temporada reproductiva produjeron espermatozoides, aunque e