Postnatal Litter Size Effects on Growth and Reproduction in Rats

Abstract

The effects of postnatal litter size on pre- and postweaning growth, daughter's litter size and rebreeding performance of the dam were examined in rats that had undergone 14 generations of selection for rate (LG) or efficiency (LE) of postweaning protein gain followed by relaxed selection, and in a randomly selected control line (C). Data came from generations 23 to 24 (standardized litters) and 25 to 26 (unstandardized litters). Generation 25 dams were remated at weaning for two additional parities. Regressions of average pup weight on average postnatal litter size were negative and increased in magnitude from birth to weaning, but decreased with parity number. Average litter size from birth to weaning (3 wk) affected postweaning weights at 5 and 7 wk, but compensatory growth occurred, especially during wk 3 to 5. The effect of dam's litter size (the litter in which the daughter was born) on daughter's weight was still negative and significant at mating and affected litter size of daughters. This negative maternal effect on daughter's litter size was larger when the dam's litter was not standardized. Litter size weaned also affected rebreeding interval of females.

Early development influences ontogeny of personality types in young laboratory rats

“…As it has been shown in previous studies (e.g., Azzam, Nielsen, & Dickerson, 1984;Mendl, 1988;Rödel, Prager, et al, 2008) Males were consistently and significantly heavier than females during the whole study period, even on postnatal day 6, when we weighed the animals individually for the first time (b males ¼ .90, p MCMC ¼ .001; R 2 Nagelkerke ¼ .11). However, there were no interactions between sex and litter size (p MCMC > .30), indicating that litter size effects on body mass had a similar negative slope in both sexes.…”

Litter size, age-related memory impairments, and microglial changes in rat dentate gyrus: Stereological analysis and three dimensional morphometry

“…However, non-lethal consequences of this natural competition may induce important differences in an individual's postnatal life. For example, growth rates are favored for subjects with greater access to maternal milk; these individuals may achieve higher reproductive success and longer lives; thus, a small litter size may represent an evolutionary advantage (Azzam et al, 1984;van Engelen et al, 1995;Stockley and Parker, 2002;Rodel et al, 2008;Rodel et al, 2010). Furthermore, it has been demonstrated that spontaneous litter size changes may affect emotionality in adulthood; these changes could not be explained by concomitant changes in maternal care (Dimitsantos et al, 2007).…”

Bodyweight Assessment of Enamelin Null Mice

“…The negative relationship between litter size and average litter BW is in accordance with previous studies. The study evaluated the effect of litter size on average pup weight in rats using regression analysis showed that the relation was negative and increased in magnitude from birth to weaning (3 wk) [31]. The effect persisted into the postweaning period; although a compensatory growth spurt seemed to occur during wk 3 to 5.…”