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At least 199 records · Page 11Linked to original sources
PubMed1987

Feed efficiency and norepinephrine turnover in iron deficiency.

Norepinephrine turnover and energetic efficiency studies were conducted in three groups of male Sprague-Dawley rats placed on low iron diets for 5 weeks on weaning. Iron-deficient rats had significant anemia (hematocrit less than 20%) and growth retardation relative to pair-fed and ad libitum fed controls who received the same diet plus weekly iron dextran injections. Energetic efficiency over a 7-day period was nearly 30% less in anemic animals. This was associated with significantly higher rates of norepinephrine turnover in brown adipose tissue (110%) and heart (330%) with significant hypertrophy in both tissues. There was no difference in body composition in ad libitum groups. Plasma triiodothyronine and thyroxine were reduced by 37% in iron deficients compared to controls. Thus 39% increase in caloric requirements in iron deficiency is associated with increased sympathetic and perhaps thermogenic activity in brown adipocytes.

Adipose Tissue↗
PubMed1992

Long-term exercise training and retirement in genetically obese rats: effects on food intake, feeding efficiency and carcass composition.

Short-term physical exercise (EX) can reduce body weight and fat gain in obese humans and animals. However, the beneficial effects of physical exercise are not long-lasting. In this study, the effects of long-term physical exercise and retirement from exercise (R) on body weight, body composition and fat distribution were examined in genetically obese (OB) and lean (LE) female rats. Fifty OB and 45 LE rats, four weeks old, were divided into EX (swimming, 2h/day, 5 days/week) or sedentary (SD) groups. At the end of the 28th week of treatment, EX groups were further divided into continued EX or R groups for another 11-12 weeks. It was found that at the end of the 28th week EX had reduced the rate of weight gain in OB and LE rats. Percentage body fat was only reduced in OBEX rats and this was achieved by a significant reduction of subcutaneous fat mass. At the end of the 40th week, EX had further reduced the weight gain, fat mass and body fat percentage in OBEX rats while only body fat percentage was reduced in the LEEX group. Retirement from exercise reversed these phenomena. Thus there were no differences between OBSD and OBEX-R rats in body weight, fat mass and percentage body fat. However, the OBEX-R group had a significantly higher amount of internal fat than the other two OB groups. Therefore, exercise, even long-term to cover the entire fat cell proliferation period, still only exerted temporary beneficial effects in OB rats. After retirement, the beneficial effects all disappeared rapidly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1993

Quantitative traits in chicken associated with DNA fingerprint bands.

In an unselected control line of a selection experiment in chicken the following traits were evaluated: number of eggs, average egg weight, egg mass, age at first egg, body weight at 20 weeks, body weight at 40 weeks, feed consumption and feed efficiency (feed consumption/egg mass). Data and blood samples of 143 females of the same age were available for analysis. The animals were ranked for each trait according to the phenotypic performance adjusted for hatch and laying house effect rather than the breeding value. DNA mixes of the top 5 and the bottom 5 hens were compared to each other by DNA fingerprinting. The most striking differences could be observed with the probe pV47 in the mixes for body weight at 20 weeks and the feed efficiency. In the following the study focused on feed efficiency. Five groups of 10 hens each, around quantiles 0%, 25%, 50%, 75% and 100%, were analyzed with respect to the occurrence of 7 particular DNA fingerprint bands. The association of the groups' mean feed efficiency with the groups' band frequencies was assessed by linear regression. For 2 bands significant regression coefficients (P < 0.005) were found.

Alleles↗
PubMed1983

Effects of 4,4'-dimethyldiphenyliodonium chloride on performance of growing cattle.

Two 112-d studies were conducted to evaluate effects of the deaminase inhibitor, 4,4'-dimethyldiphenyliodonium chloride, on performance of growing cattle. With diets containing low levels of crude protein (i.e., 11%), 25 ppm of chemical in the diet increased (P less than .05) gain and improved (P less than .05) feed efficiency. Feed intake was not affected. Higher levels of chemical (50 and 100 ppm) produced equivalent responses. With a higher level of dietary crude protein (i.e., 14%) gain and feed efficiency were not improved and some decreases in feed intake were observed. Performance responses resulting from adjustments in ruminal nitrogen transactions to provide more alpha-amino-N depend upon whether the animal needs additional amino acids for maintenance and production. Our data demonstrated that the supply of amino acids can be increased either by adjustment of ruminal nitrogen transactions with a chemical agent or by increasing concentration of dietary protein.

Animals↗