In this study we examined the body composition of rats recovering from overfeeding, underfeeding or starvation. Female rats (220 g) were fed 160%, 100% or 40% of control intake, by stomach tube, until the 40% rats had lost 50 g. Other rats were starved to lose 50 g. Carcass composition was measured on one group from each treatment. The remaining rats returned to ad libitum feeding. The 160% rats were hypophagic and lost weight. Starved and 40% rats were hyperphagic and gained weight. Serum insulin increased with increased food intake. T4 was depressed by food restriction. T3 and T4 increased during weight loss in 160% rats. Carcass composition of rats from each treatment was determined at progressive stages of recovery. Overfed rats had gained 7 g of protein and 43 g of fat. Protein was soon lost but fat was still significantly increased after 44 d of recovery. Starved and restricted rats had lost 11 g of protein and 28 g of fat. Starved rats regained protein earlier than body fat. Restricted rats recovered body fat much earlier than body protein or weight. Body protein and fat may have individual regulatory mechanisms that work together to control body weight.
One hundred twenty crossbred beef steers averaging 377 kg were used in a 2 x 4 factorial experiment to determine the dose-response effects of recombinant bovine somatotropin (rbST) implants on growth performance and carcass characteristics. The implant dosages were 0 (sham), 40, 80, or 160 mg/wk administered s.c. in the tailhead region on a weekly basis throughout the experiment. The steers were fed a high-concentrate diet, which contained either a degradable (DP; soybean meal) or an escape (EP; corn gluten and blood meal) protein source. No dietary protein effect or dietary protein x rbST level interactions were detected. Recombinant bST decreased both DMI (P less than .10) and feed/gain (P less than .05) in a linear dose-dependent manner. Dosage of rbST did not significantly affect (P greater than .10) ADG or final weight of the steers. Recombinant bST decreased backfat depth (P less than .10), marbling score (P less than .05), and quality grade (P less than .10) and increased yield grade (P less than .10) in a linear dose-dependent manner. Soft tissue composition of the 9-10-11th rib section was altered (P less than .01) by rbST administration in a linear dose-dependent manner. The percentage of protein in the rib section was increased by 9.4% and fat was decreased by 11.8% at the 160 mg/wk rbST level compared with the sham-implanted steers. Recombinant bST did not affect (P greater than .10) dressing percentage, hot carcass weight, kidney, pelvic, and heart fat, or longissimus muscle area.(ABSTRACT TRUNCATED AT 250 WORDS)
To create a behavioral classification of obesity, 2-wk baseline food diaries were obtained from 236 obese women entering weight-loss programs. Subjects monitored food intake along with the social, environmental, and emotional context in which each meal occurred. Variables representing situation-specific eating behaviors were statistically extracted from greater than 11,000 eating episodes. Hierarchical cluster analysis identified five distinct groups of subjects on the basis of similarity of eating patterns. The five groups were (1) moderately healthy eating habits, (2) chronic food restrictors, (3) alternating diet-binge eaters, (4) emotional overeaters, (5) unrestricted meal overeaters. The five groups differed on questionnaire measures of emotional adjustment and eating behavior but did not differ on dropout rates, amount of weight lost, or exercise compliance. The chronic food restrictors had significantly less lean body mass, lower resting metabolic rates, and higher waist-to-hip ratios than did the unrestricted meal overeaters.
Experiments were conducted in pregnant pigs to determine the influence of alloxan diabetes and maternal fasting on fetal development. Maternal fasting and alloxan diabetes both increased adipose tissue thickness in fetuses at 112 days of gestation without altering body weight. Body fat was increased quantitatively only in the fetuses from the diabetic pigs (FDP). Apparently, different factors were affecting the structural development of adipose tissue and the actual storage of lipid. Fetal and maternal hepatic fatty acid synthesis were unaffected by treatments. Maternal subcutaneous adipose fatty acid synthesis was depressed by 75% in both fasted and diabetic dams while subcutaneous adipose tissue lipogenesis was increased 40-fold in the FDP. Enzymes normally associated with lipogenesis (shunt enzymes) were also affected in a similar fashion. These observations support the concept that fetal adipose de novo fatty acid synthesis is stimulated by diabetic pregnancies and is a primary mechanism by which increased lipid accumulates in the fetus.
Newborn Yorkshire and Ossabaw (feral) pigs were examined under thermoneutral conditions to determine whether survival rate during fasting differs between these breeds and whether any blood-borne factors are associated with improved survival. Newborn pigs were removed from the sow before suckling. Body composition was determined on 10 newborn Ossabaw and 12 newborn Yorkshire pigs. Another group of animals (eight Ossabaw, 12 Yorkshire) was fasted for 72 hr, with blood samples drawn at birth and 12 and 24 hr into fasting. Glucose, free fatty acid (FFA), growth hormone (GH), insulin, thyroxine (T4), triiodothyronine (T3), cortisol and glucagon concentrations were measured in plasma of fasted pigs. Concentrations of carcass lipid, dry matter and ash were higher in newborn Ossabaw pigs than in newborn Yorkshire pigs. Survival through 72 hr of fasting was lower among Yorkshire pigs. Yorkshire and Ossabaw pigs had similar concentrations of metabolites and hormones at birth, with the exceptions of lower plasma GH and higher T3 concentrations in Ossabaw pigs. Higher plasma T3 concentrations would indicate a greater potential for fatty acid oxidation. During fasting, Ossabaw pigs had lower plasma GH and T4 concentrations and higher glucagon and FFA concentrations. Increased survival among newborn Ossabaw pigs may have been due to increased availability of FFA during fasting, and to a greater potential for gluconeogenesis through increased oxidation of fatty acids and higher plasma glucagon concentrations. This would suggest that maternal treatments that would increase storage of fat and(or) increase the capacity for oxidation of fat in utero would improve survival of newborn pigs.
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