ABSTRACT
Maternal care is very important for infant development, mainly for altricial species such as rodents. This study was carried out in order to analyze the differences between the maternal behavior and infant development in two species of rodents regarded as gregarious and solitary. Thus, the behavior of 40 lactating females (20 golden hamster and 20 albino rat mother, or GH and AR) and their litters was recorded from the 1st to the 35th day after partirition. On the 4th day, litters were culled to 4 pups (all males or all females) and animals were grouped as follows: Groups I and II (litters consisting of all-male or all-female GH pups) and Groups III and IV (litters consisting of all-male or all-female AR pups). It was noted that GH mother spent a higher mean time in bodily interactions with pups and nest-building activity. All mothers axhibited higher pup retrievals and licked their pups more frequnatly around the 15th day, but GH mother exhibited a higher mean number of pup retrievals and licked their pups less frequantly. The emergence of pup self-licking around the 15th day coincided with the abrupt decrease in the maternal licking in both GH and mother. GH gained body mass more rapidly and their mothers lost a significant amount of body weight during the lactation, in contrast to the body weight gain by AR mother during the same period: On the 20th day, GH and AR mother exhibited 88.6 percent and 110.8 percent of their body mass, respectively, suggesting that the rearing costs are higher for GH mothers. We concluded that the behavior of animals may be explained in accordance with the differences in their habitats (desert or savanna), level of gregariousness, and also the characteristics of pup development.
Subject(s)
Animals , Male , Female , Rats , Cricetinae , Behavior, Animal/physiology , Maternal Behavior/physiology , Mesocricetus/growth & development , Rats, Inbred Strains/growth & development , Postpartum PeriodABSTRACT
O estudo da interaçäo mäe-filhote, dentro de um enfoque ontogenético, pode esclarecer muito acerca das características e funçöes do comportamento. Assim sendo, 12 fêmeas foram observadas desde o nascimento de seus filhotes até o 25§ dia post-partum. Observou-se que: a) surtos de locomoçäo do filhote säo mais freqüentes a partir do 10§ dia - antes disso, a locomoçäo é pouco freqüente e ocorre somente dentro do ninho -; b) recuperaçöes dos filhtes atingem o seu ponto máximo por volta do 16§ dia, período em que as fêmeas mais se afastam do ninho; c) o tempo que a mäe dispende em contato físico com o filhote decai gradativamente à medida que este ganha idade; d) comportamentos que exigem um maior desenvolvimento motor (autolimpeza, brincadeira, locomoçäo e manipulaçäo de material de ninho) ou que indicam uma independência física (comer e beber) ocorrem por volta do 10§ dia de vida do filhote; e) o tempo dispendido pela mäe na arrumaçäo do ninho permaneceu bastante irregular até o 18§ dia, tendo, a partir daí um visível decréscimo; f) a auto-limpeza da mäe tem um ligeiro aumento por volta do 2§ dia e, logo em seguida, permanece constante até o final das observaçöes. Concluímos que a interaçäo mäe filho no hamster é um sistema bastante dinâmico, que evolui à medida que o filhote ganha independência
Subject(s)
Animals , Female , Cricetinae , Maternal Behavior , Age Factors , Locomotion , Mesocricetus/growth & development , Motor Activity , Time FactorsABSTRACT
La administración de una dosis única de clindamicina a hamsters dio lugar a la producción de una cepa de C. difficile de baja producción de toxina. La colonización se hizo constante y evidente después de seis meses de administrar el antibiótico. El tratamiento se asoció a un exagerado crecimiento cecal y retraso en el crecimiento en comparación con los animales no tratados. Se infiere que la exposición prolongada a bajos niveles de la toxina de C. difficile puede determinar disfunción del ciego y desnutrición