Time of birth and daily activity mediated by feeding rhythms in the pregnant rat

Abstract

Summary. The food was available ; they were noted in all groups at times when the animals were least active according to records kept throughout gestation. Thus, restricting food availability to periods of normal inactivity (groups 9PF and 14PF vs group C) led to a major shift in the time of delivery as well as to a distortion of the normal activity patterns. These results confirm that feeding rhythms are potent entrainers of birth time in rats and that they interact with the light regime. Pregnant rats seem to be organized so that birth either precedes the main daily physical activity or follows it, depending upon the environmental conditions. Introduction.

Influence of feeding regime on timing of parturition in beef cattle and the relationship of vaginal temperature to parturition

“…It has been previously reported that a low percentage of lambs (Sharafeldin et al . 1971) and rats (Bosc et al . 1986) were born around the time when concentrates were fed.…”

Photoperiod and parturition period in isolated or paired rats : influence of sight deprivation and social conditions

“…The dams were on the average a little heavier just after parturition than on day 8 of gestation in all groups, except in group E 2 in which they were a little lighter (on the average 7 g less). (Moore, 1979;Rusak and Zucker, 1979), even if light is directly transmitted to the brain as shown in adult ewes (Van Brunt et al, 1964) or in rats and guinea pig fetuses (Jacques et al, 1987 (Bosc and Nicolle, 1980b (Bosc et al, 1986). This lack of birth for a significant time indicates that parturition can be initiated during given hours of the day according to a gate system which can be reset by photoperiod or other environmental cues (Bosc and Nicolle, 1985;Bosc et al, 1986 (Psychoyos, 1973), or it may result from unspecified effects of sight deprivation.…”

“…Après l'anesthésie, elles ont été gardées isolées (N ou E) ou en paires homogènes (NN et (Mitchell and Yochim, 1970;Plaut et t al., 1970;Lincoln and Porter, 1976;Bosc and Nicolle, 1980a), and therefore the birth mechanism, by endogenous events which are finally integrated at the uterine and cervical levels. Other environmental cues can also modify the time of birth in this species, as in the case of periodic food presentation (Bosc and Nicolle, 1985;Bosc et al, 1986) and probably of social environment (Bosc and Nicolle, 1985). In order to evaluate the possibility of a social influence on the time of parturition, pairs of normal and/or blinded rats were subjected to two different light regimens.…”