BODY-WEIGHT AND COMPOSITION IN THE SPRAGUE-DAWLEY RAT - COMPARISON OF3 OUTBRED SOURCES

Body weight with age and final composition for water, fat, and protein , were measured in three outbred stocks derived from the Sprague Dawle y rat, Three groups of 10 individually housed male rats hom three outb red colonies (Crl:CD[SD]BR, Hsd:SD[SD], and Tac:N[SB]fER) provided wit h standard rodent chow and water ad libitum were weighed weekly for 56 consecutive weeks. Rats in each group were born on the same day, and each group was born within a 4-day period. Significant group effects w ere found for upper weight limit, carcass weight, water, and fat conte nt (P < 0.05), The Hsd:SD(SD) and Tac:N(SD) rats grew, in proportion t o their upper weight limits, at a faster rate (P < 0.01) and contained a greater percentage of body protein (P < 0.05) than did heavier, rep ortedly shorter-lived Crl:CD(SD)BR rats.