Lifetime breeding studies in fully fed and dietary restricted female CFY Sprague-Dawley rats. 1. Effect of age, housing conditions and diet on fecundity.
Level 5 - mechanism / opinion, no new human data
Animal research with no human data.
PubMed 4079476 · doi:10.1016/0047-6374(85)90106-x
What was done
Female CFY Sprague-Dawley rats were evaluated for their ability to bear multiple litters across their lifespan when breeding commenced at increasing ages. The study compared five conditions: continuous cohabitation with a male (GC), intermittent breeding in group-housed fully fed rats (GI), intermittent breeding in individually housed fully fed rats (I), dietary restriction (DR), and refeeding following dietary restriction (DRA). Measured outcomes included the percentage of females pregnant, number of litters produced, and total litter size.
What was found
Individual housing did not affect the percentage of females pregnant or the number of litters produced, but caused a significantly steeper decline in total litter size with maternal age compared to group housing (GI), matching the regression slope of continuous breeding (GC). Dietary restriction reduced litter size and overall fertility but extended breeding capacity up to 937 days of age, compared to a maximum of 720 days in all fully fed groups, with no age-related decline in litter size while restricted. Refeeding (DRA) restored the rate of litter size decline to that of GI rats; all DRA cohorts produced up to three litters, with breeding initiated at 750 days yielding litters as late as 952 days. Exact numerical counts and percentages were not reported in the abstract.
Why it matters
The findings demonstrate that dietary restriction substantially delays reproductive senescence in female rodents, preserving fertility into advanced age at the expense of immediate fecundity.
Limits
This is an animal study in Sprague-Dawley rats, limiting direct applicability to human reproductive biology. The abstract omits sample sizes, exact dietary restriction percentages, numerical litter counts, confidence intervals, and specific statistical test metrics.
Cited by
- supports If female rats on 40% calorie restriction that have ceased cycling are returned to ad libitum feeding, they regain weight, resume cycling, and maintain fertility to an older age than continuously ad libitum-fed rats.