Effect of age and body weight on the maintenance requirement of lean and obese Zucker rats.
The effect of age (34-215 days) and body weight (80-627 g) on the maintenance requirements of lean (n = 4) and obese (n = 4) Zucker rats was determined in 5 maintenance trials. The rats were fed a semipurified, 20% protein diet. The metabolizable energy intake (MEI) required for maintenance of body weight (BW) was determined in weekly intake-metabolism trials. Maintenance requirements [kilocalories MEI/(day.kilogram BW)] were lower (P less than 0.01) for obese rats than for lean rats, and they decreased with age for both types, respectively (Y = 206.23 - 0.3524 X; r = -0.547 and Y = 252.61 -0.4818 X; r = -0.649). Maintenance requirements (kilocalories MEI/day) of obese rats were lower (P less than 0.01) than lean rats, respectively, when expressed in terms of grams body weight (Y = 7.03 + 0.1333 X; r = 0.994 and Y = 9.04 + 0.1441 X; r = 0.994), metabolic body size (kilogram 0.75) (Y = -4.52 + 132.33 X; r = 0.989 and Y = 0.05 + 130.52 X; r-0.992) or least squares, type-specific exponent [Y = 119.03 (kilogram0.77); r = 0.975 and Y = 120.87 (kilogram 0.71); r = 0.986]. The results indicate that obese Zucker rats have lower maintenance requirements than their lean littermates and that maintenance requirements are as closely related to body weight as to metabolic body size or type-specific exponent for each body type.
D000375:Aging; D000818:Animals; D001824:Body Constitution; D001835:Body Weight; D004032:Diet; D004734:Energy Metabolism; D008297:Male; D009751:Nutritional Requirements; D009765:Obesity / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness / Q000378:metabolism*