Biomaterial Database

Postnatal litter size effects on growth and reproduction in rats. 1984

S M Azzam, and M K Nielsen, and G E Dickerson

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.

UI	MeSH Term	Description	Entries
D008098	Litter Size	The number of offspring produced at one birth by a viviparous animal.	Litter Sizes,Size, Litter,Sizes, Litter
D008297	Male		Males
D011247	Pregnancy	The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.	Gestation,Pregnancies
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
D012098	Reproduction	The total process by which organisms produce offspring. (Stedman, 25th ed)	Human Reproductive Index,Human Reproductive Indexes,Reproductive Period,Human Reproductive Indices,Index, Human Reproductive,Indexes, Human Reproductive,Indices, Human Reproductive,Period, Reproductive,Periods, Reproductive,Reproductive Index, Human,Reproductive Indices, Human,Reproductive Periods
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D014886	Weaning	Permanent deprivation of breast milk and commencement of nourishment with other food. (From Stedman, 25th ed)	Weanings
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus