Development and reproductive performance of Swiss mice in an enriched environment

Abstract

The present study investigated the effects of environment enrichment on the development and reproductive performance of an outbred Swiss strain. Physical enrichment consisted of free access of animals to tubular devices of different shapes and sizes. The development evaluation was done by monitoring growth rate during 39 days, from weaning (21 days) to the onset of sexual maturity (60 days of age). Over five consecutive gestations (105 days), the following variables were monitored: litter size, number of animals born alive; number of pups alive at 12 hours and on days 4, 9, 12, 15 and 18; number of animals weaned per litter; average weight of litters on days 4, 9, 12, 15 and 18. The reproductive performance was then evaluated using the inclusion of these variables in the indices of gestation and birth, viability, lactation, survival success, mating success and production. The results showed that the environmental enrichment did not influence, in a significant way, the evaluated parameters. However, there is no reason to deprive the animals from an enriched environment where they can develop their natural instinctive behaviour and guarantee health and well-being.Keywords: environmental enrichment, development, reproductive performance, mice. Desenvolvimento e performance reprodutiva de camundongos Swiss em ambiente enriquecidoResumo O presente estudo investigou efeitos do enriquecimento ambiental sobre o desenvolvimento e a performance reprodutiva de camundongos outbred da linhagem Swiss. O enriquecimento teve como base o livre acesso dos animais a dispositivos tubulares de tamanhos e formas diferentes. A avaliação do desenvolvimento a partir da taxa de crescimento decorreu por um período de 39 dias, desde o desmame (21 dias) até os 60 dias de vida (maturidade sexual). Durante cinco gestações consecutivas (105 dias), foram registradas as seguintes variáveis: média do tamanho da ninhada, nú-mero de animais nascidos vivos; número de filhotes vivos em 12 horas, e nos dias 4, 9, 12, 15 e 18; número de animais desmamados por ninhada; e a média do peso dos filhotes nos dias 4, 9, 12, 15 e 18. A performance reprodutiva foi então avaliada a partir da inclusão dessas variáveis nos índices de gestação e nascimento, viabilidade, lactação, sucesso de sobrevivência, sucesso de acasalamento e produção. Os resultados obtidos mostraram que o enriquecimento ambiental não influenciou significativamente no desenvolvimento e na performance reprodutiva de camundongos da linhagem Swiss para nenhum dos parâmetros avaliados. Contudo, não há motivo para privar os animais de um ambiente enriquecido onde possam desenvolver seu comportamento instintivo natural e, consequentemente, viver com saúde e bem-estar.Palavras-chave: enriquecimento ambiental, desenvolvimento, performance reprodutiva, camundongo.

Environmentally Enriched Male Mink Gain More Copulations than Stereotypic, Barren-Reared Competitors

“…Enrichment enhances male mating success in laboratory-reared flies [74] , [75] ; prolongs reproductive lifespan in domestic hens [76] ; and in mammals, enrichment seems to increase the number of infants succesfully weaned by females in laboratory mice [77] (though cf. [78] ) and farmed mink [79] . However, no study has investigated the effects of enrichment in both sexes, through all stages of reproduction from mating inspections to weaning; nor has any study identified the mechanisms underlying any observed success.…”

Long-Term Effect of Environmental Enrichment on Reproductive Performance of Swiss Webster Mice and Their Female Offspring

“…Additionally, it has been found that EE promotes a greater number of viable oocytes induced by superovulation in rats [ 16 ]. On the other hand, other authors did not find any effect of EE on reproductive parameters [ 17 , 18 ]. Despite these findings, further information is required on the effect of EE on reproduction in mice breeding colonies and their progeny.…”

“…Previous studies in mice reported controversial findings on the effect of EE on reproductive performance. Some authors suggest that EE does not affect the reproductive outcomes of Swiss Webster and C57BL/6J mice using physical enrichment, such as plastic devices of different shapes and sizes, or cotton squares [ 17 , 18 ]. On the other hand, other authors reported that physical EE items and the period of exposure resulted in larger body weights of the F1 or F2 offspring generations, addressing a relevant phenotype effect [ 22 ].…”

Nicotina y modelos animales: ¿qué nos aporta el paradigma de enriquecimiento ambiental?

“…En última instancia, se trataría de "enriquecer el ambiente para potenciar al cerebro" (Sale, Berardi, y Maffei, 2009). Esta complejidad proporciona también estimulación a nivel visual, somatosensorial e incluso olfatorio (Carvalho, Araujo, Farias, Rocha-Bezerra, y Cavalheiro, 2009;Nithianantharajah y Hannan, 2006;Redolat y Mesa-Gresa, 2011). El periodo durante el cual se mantienen los animales en estas condiciones y la edad de los mismos varía en función de los objetivos del estudio, de los análisis y pruebas que se realicen y de las hipótesis que guíen la investigación.…”