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Results for “Restrictive”

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PubMed1996

Expression of heat shock protein 70 in rat spleen lymphocytes is affected by age but not by food restriction.

The purpose of this study was to determine if food restriction alters the age-related decline in heat shock protein 70 (hsp70) expression in lymphocytes from male Fischer 344 rats. Spleen lymphocytes were isolated from young (6 mo) and old (24 mo) rats that had free access to food (control group) and from food-restricted old (24 mo) rats that, beginning at 6 wk of age, were fed 60% (40% food restriction) of the diet consumed by the control rats. Lymphocytes were either heat shocked (42.5 degrees C for 1 h) or maintained at 37 degrees C (control). The levels of hsp70 protein and mRNA and the induction of interleukin-2 (IL-2) mRNA by concanavalin A (conA) were measured in these rats. In addition, the percentage of viability (as an index of thermosensitivity) of the lymphocytes from these rats was also measured after exposure of cells to different temperatures (first at 42.5 degrees C and then 45 degrees C). We found that the induction of hsp70 protein and mRNA in lymphocytes isolated from control old rats and food-restricted old rats was lower (P < 0.001) than that in control young rats. However, the levels of hsp70 and mRNA in lymphocytes isolated from food-restricted old rats were similar to the levels in age-matched control rats. Lymphocytes from both control old rats and food-restricted old rats were more thermosensitive than lymphocytes from control young rats; however, thermosensitivity of lymphocytes from food-restricted old rats was similar to that of age-matched control rats. The induction of IL-2 mRNA levels by conA was significantly (P < 0.001) lower in old than in young control rats. In contrast to hsp70, which was not affected by food restriction, the induction of IL-2 mRNA was higher (P < 0.05) in food-restricted old rats than in age-matched control rats. Therefore, food restriction has a differential effect on gene expression.

Aging↗

PubMed1998

Dietary restriction of energy and calcium alters bone turnover and density in younger and older female rats.

To determine the influence of weight loss with or without adequate calcium intake on bone turnover and density, we examined the influence of dietary restriction of calcium or energy on body weight (BW), bone mineral density (BMD) and bone turnover in both younger (3 mo) and older (10 mo) female rats (n = 66). Diets were designed to allow feeding at two levels of calcium intake (normal = 78 mg/d and low = 15 mg/d) and two levels of energy intake (normal and 40% restriction) while keeping the intake of protein, fat, fiber, vitamins and other minerals equal between groups. Thus rats received either a control diet (CNTL), a diet restricted in calcium, energy or both for 9 wk. Energy restriction reduced BW 5-21% (P < 0.01) and elevated bone formation 10-20% (P < 0.05) in both age groups. Bone resorption was 20-40% above CNTL values (P < 0.05), in rats fed all three restricted diets. In younger rats, BMD increased over time in all groups (P < 0.05), but final BMD was lower in calcium restricted groups compared with CNTL (P < 0.01). In older rats, CNTL had a significantly greater final BMD (P < 0.05) than diet-restricted groups. These data indicate that, in both younger and older rats, dietary restriction of calcium or energy results in an elevated rate of bone turnover. BMD is compromised by calcium restriction in both younger and older rats, whereas only older rats were negatively influenced by dietary energy restriction. Thus the present study indicates a detrimental effect of low-energy diets, as well as inadequate calcium intake, on bone density in mature rats.

Aging↗

PubMed2001

Inflammatory responses to lipopolysaccharide are suppressed in 40% energy-restricted mice.

To elucidate the suppressive effects of energy restriction on the inflammatory responses to lipopolysaccharide (LPS), mice were divided into a control group (fed 5.0 g diet/d; 71 kJ/d) and a 40% energy-restricted group (fed 3.0 g diet/d; 43 kJ/d) at 8-wk of age. Four weeks later, 25 microg of LPS was intraperitoneally injected. After the LPS injection, interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha were elevated in serums in the 40% energy-restricted mice and in the controls, but the extent of the elevation was significantly lower in the restricted group. The LPS-induced expression of inducible nitric oxide synthase in the liver was significantly suppressed by the energy restriction. In addition, the LPS-induced elevations of serum aspartate and alanine aminotransferase activities, which are indexes of hepatic injury, were also significantly attenuated in the restricted group. Moreover, the extent of LPS-induced alterations in hepatic structure was less in the restricted mice than in controls. Serum corticosterone level in the restricted mice was higher than that in the controls before LPS treatment (P < 0.05). Furthermore, after LPS injection, the significantly higher level of corticosterone was maintained in the restricted mice, although the LPS treatment significantly enhanced the level even in the control group. These results suggest that the extreme inflammatory responses to endotoxin are prevented in the 40% energy-restricted mice, and corticosterone participates in the preventive effects.

Animals↗

PubMed2003

Work restrictions and outcome of nonspecific low back pain.

STUDY DESIGN: Retrospective cohort study was conducted. OBJECTIVE: To evaluate the association of prescribed work restrictions with work absenteeism and recurrence in cases of nonspecific low back pain. SUMMARY OF BACKGROUND DATA: The efficacy of commonly prescribed work restrictions in limiting sickness-related absence because of back pain has not been evaluated. METHODS: Employees who had back pain-related sickness absence were identified from medical records of a utility company. The workers were grouped into those who had received a work restriction for their back pain and those who had not. The duration of work disability was compared between the two groups. Employees who returned back to regular, full duty within 1 year of onset were followed for one additional year to determine rates of recurrence. The Cox Proportional Hazards model was used to generate hazard ratios adjusted for age, gender, and job category. RESULTS: Restrictions were given to 43% of the workers. Sickness absence duration did not differ between those who had received restrictions and those who had not (adjusted hazard ratio, 1.12; P = 0.41). The median duration of restricted duty was 32.5 days. For 22% of the workers, restricted duty was never lifted. Recurrence appeared less likely to occur among those who had work restrictions in their initial episode. However, this difference was not statistically significant (adjusted hazard ratio, 0.77; P = 0.48). CONCLUSIONS: No evidence of an association between a prescription of work restriction and early return to work was found. More research is needed to clarify the utility of restricted duty in promoting a positive outcome for work-related low back pain.

Absenteeism↗

PubMed2004

Effects of ageing on the energy balance of food-restricted rats.

AIMS: Age can alter energy balance by decreasing the resting metabolic rate. Food restriction can also change energy balance by decreasing energy expenditure as a mechanism of energy conservation. We investigated the influence of food restriction on the energy balance of rats at different ages. METHODS: Wistar EPM-1 female rats were used at ages of 3, 9, 15 and 21 months. At each age, two food intake schedules were provided: control (ad libitum) and food restriction (50%). Animals remained under these schedules for 30 days, and throughout this period body weight, food intake, and stool collection were controlled daily. On the 30th day, animals were killed, blood was collected and the carcasses and faeces were processed for analysis by pump calorimetry. Blood glucose, T(3), T(4) and rT(3) levels were determined. RESULTS: Food restriction reduced energy gain and gross food efficiency of animals at different ages, but more so in older animals. Food-restricted rats also had lower energy expenditure than controls. This reduction was about 40% of the energy expenditure of control animals irrespective of age. Water content increased and fat content decreased in the carcass of food-restricted animals. Serum T(3) and T(4) levels were lower in food-restricted animals pointing out to a major role of thyroid hormones in the mechanism of energy conservation exhibited by food-restricted animals. CONCLUSIONS: The mechanism of energy conservation takes place in all restricted animals and is very important for survival and for species preservation, mainly in aged animals in which food restriction is frequently aggravated by senescence-related organic disorders.

Adipose Tissue↗

PubMed2003

Effect of nutritional restriction in early pregnancy on isolated femoral artery function in mid-gestation fetal sheep.

Unbalanced maternal nutrition affects fetal endocrine and cardiovascular systems, sometimes accompanied by changes in growth, although this is usually in late gestation. We determined the effect of moderate restriction for the first half of gestation of maternal dietary protein, or of total calorific intake on isolated resistance artery function of mid-gestation fetal sheep. Welsh Mountain ewes were nutritionally restricted by 30 % of the recommended nutrient intake (globally restricted) or 30 % of the recommended protein intake (protein-restricted), compared to control ewes fed 100 % of recommended nutrient intake, for ~12 days prior to conception and for the subsequent 70 days of gestation. At mid-gestation, fetal and placental weights were similar in all dietary groups. In isolated femoral arteries, the response curve to noradrenaline was reduced in protein-restricted group fetuses (P < 0.05). Maximal relaxation (P < 0.01) and sensitivity (P < 0.05) to acetylcholine were markedly reduced in protein-restricted group fetuses, and to a smaller extent in globally restricted group fetuses (response curve, P < 0.05). The dilator response (P < 0.05) and sensitivity (P < 0.05) to the alpha2 agonist UK14304 was lower in protein-, but not in globally restricted group fetuses. The response (P < 0.05) and sensitivity (P < 0.05) to the nitric oxide donor sodium nitroprusside were reduced in protein-restricted group fetuses compared to controls. Our data show that dietary imbalance, in particular restricted protein, of the ewe can produce blunting of endothelial-dependent and -independent relaxation in systemic arteries from the mid-gestation fetus. These changes may precede perturbed late-gestation fetal and postnatal cardiovascular control.

3-Hydroxybutyric Acid↗

PubMed1972

Degradation of bacteriophage lambda deoxyribonucleic acid after restriction by Escherichia coli K-12.

Wild-type bacteria which restrict the deoxyribonucleic acid (DNA) of infecting phage when the phage do not carry the proper host modification rapidly degrade that restricted DNA to acid-soluble products. The purified restriction enzyme acts as an endonuclease in vitro to cleave restrictable DNA and does not further degrade the DNA fragments produced. We have examined mutants of Escherichia coli K-12 which lack various nucleases in order to determine which nucleases are involved in the rapid acid solubilization in vivo of unmodified lambda DNA following restriction. Bacteria which are wild type, recA(-), or polA1(-) degrade about 50% of the unmodified phage DNA within 10 min of infection, with little subsequent degradation. Mutants which are recB(-) or recC(-) degrade unmodified DNA very slowly, solubilizing about 15% of the DNA by 10 min after infection. Two classes of phenotypic revertants of recB(-)/C(-) mutants were also tested. Bacteria which are sbcA(-) restrict poorly and do not degrade much of the restricted DNA. Bacteria which are sbcB(-) restrict normally. This mutation does not appear to affect degradation of restricted phage DNA in recB(-)/C(-) mutants, but such degradation is decreased in recB(+)/C(+) bacteria. The presence of a functional lambda exonuclease gene is not required for degradation after restriction.

Adenosine Triphosphate↗

PubMed1973

Restriction and modification of bacteriophage S2 in Haemophilus influenzae.

The major conclusion from these studies is that variants of Haemophilus influenzae Rd which restrict and modify phage S2 are metastable and capable of giving rise to one another with high frequency. Nonrestrictive RdS cells segregate spontaneously to the restricting, modifying phenotype in about 5% of the progeny of a single clone. The restrictive cells derived from RdS revert to the nonrestrictive phenotype in 15 to 25% of the progeny of a single clone. These frequencies are not appreciably affected by treatment with acriflavine or ethidium bromide, compounds which affect plasmid stability, or by nitrosoguanidine, a powerful mutagen. The genetic locus for restriction and modification of bacteriophage S2 is found to have a chromosomal position between the biotin and proline loci. Restriction-modification of phage S2 has been shown to be a function of its deoxyribonucleic acid (DNA) in that transfection with S2 phage DNA or prophage DNA is subject to host restriction and modification. An enzyme preparation, which contains endodeoxyribonuclease but no appreciable exonuclease activity, from mutant H. influenzae com(-10) did not restrict phage S2.RdS DNA or prophage DNA transfecting activity, indicating that this endodeoxyribonuclease is not responsible for phage restriction. A new restriction enzyme isolated from H. influenzae Rd was found to be the major enzyme involved in the restriction of bacteriophage S2. The enzyme inactivated the transfecting activity of unmodified phage DNA but did not attack modified phage DNA. Unlike endodeoxyribonuclease R, this enzyme requires adenosine triphosphate and S-adenosylmethionine.

Acridines↗

PubMed1987

Immunoglobulins A and G2a in milks of protein- and calorie-restricted dams.

It is well accepted that breast-feeding enhances the ability of newborns and infants to be protected against infection. Maternal nutritional status may affect this passive immunological defense mechanism because of either the change in the volume of milk or the alteration of the immunological components secreted in the milk. Diet restriction in lactating dams has been shown to influence the secretion of immunoglobulin in their milk. We investigated the specific role of caloric or protein restriction on immunoglobulin A (IgA) and IgG2a secretion in the milk of lactating rats. Both calorie- and protein-restricted dams had lower protein levels (milligrams per milliliter) than did the controls during the initial days of lactation (P less than 0.05). The levels (milligrams per milligram of protein) of IgA and IgG were higher in the milk obtained from calorie-restricted dams during the whole lactation period. The amount of IgA in the milk of protein-restricted rats was higher during 21 days of lactation, while the amount of IgG2a was higher only during the first 2 weeks of the lactation period compared with the respective values for the milk from control dams (P less than 0.05). Rats on a protein-restricted diet had lower IgA and IgG2a levels in their milk than those on a calorie-restricted diet at the second half of the lactation period (P less than 0.05). Our data suggest that the diet-restricted dams had a compensatory mechanism to ensure passive immunological protection for their pups during lactation. The compensation was diminished with a protein-restricted diet compared with a calorie-restricted diet.

Animals↗

PubMed2004

Lv2, a novel postentry restriction, is mediated by both capsid and envelope.

The characterization of restrictions to lentivirus replication in cells identifies critical steps in the viral life cycle and potential therapeutic targets. We previously reported that a human immunodeficiency virus type 2 (HIV-2) isolate was restricted to infection in some human cells, which led us to identify a step in the life cycle of HIV-2 detected after reverse transcription but prior to nuclear entry. The block is bypassed with a vesicular stomatitis virus glycoprotein G (VSV-G) envelope (A. McKnight et al., J. Virol. 75:6914-6922, 2001). We hypothesized that, although the restriction is apparent at a post-reverse transcription step, the lack of progress results from a failure of the virus to reach a cellular compartment with access to the nucleus. Here we analyzed molecular clones of the restricted virus, MCR, and an unrestricted virus, MCN. Using sequence analysis and gene swapping, we mapped the viral determinants to gag and env. Site-directed mutagenesis identified a single amino acid at position 207 in CA to be responsible for the gag restriction. Pseudotype experiments indicate that this step is also important for the infection of cells by HIV-1. The HIV-1 NL4.3 core is restricted if supplied with a restricted MCR envelope but not with VSV-G. Also the NL4.3 envelope rescues the restricted core of HIV-2 MCR. Abrogation experiments with MLV demonstrate that the restriction is distinct from Fv1/Ref1/Lv1. We propose that this represents a new lentiviral restriction, Lv2. Thus, the envelope and capsid of HIV act to ensure that the virus is delivered into an appropriate cellular compartment that allows postentry events in viral replication to proceed efficiently.

Animals↗

PubMed1998

Influence of restricted maternal nutrition in early to mid gestation on placental and fetal development at term in sheep.

We investigated the influence of restricted maternal nutrition between 28 and 77 d of gestation on placental weight and appearance, and on fetal weight and conformation. Single-bearing ewes were fed either twice [i.e. controls (n = 19)] or half [i.e. nutrient-restricted (n = 28)] their energy requirements from 28 to 77 d of gestation, after which all ewes were fed to fully meet the energy requirements for maintenance and pregnancy. Close to term (145 +/- 1 d) placental weight was higher in the nutrient-restricted group [nutrient-restricted, 416.3 +/- 12.6 g; controls, 347.4 +/- 17.6 g (p < 0.01)], as was the abundance of everted placentomes. There was no significant difference in total fetal weight, or weights of individual organs between groups, but crown-rump length was significantly greater in lambs born to nutrient-restricted ewes [nutrient-restricted, 50.4 +/- 0.4 cm; controls, 48.2 +/- 0.6, cm (p < 0.01)]. Fetal to placental weight ratio was lower in the nutrient-restricted group [nutrient-restricted, 9.51 +/- 0.23; controls, 10.81 +/- 0.39 (p < 0.01)]. A stronger relationship between the total weight of the fetal component of the placental and fetal weight was observed in controls (r2 = 0.50) than in nutrient-restricted ewes (r2 = 0.18). In conclusion, maternal nutrient restriction over the period of rapid placental growth results in a larger placenta and altered placental to fetal weight ratio if ewes are subsequently fed to requirements for the remainder of gestation.

Analysis of Variance↗

PubMed1998

Effect of restricted nutrition on timing of puberty in female Soay sheep.

Ovariectomized, oestradiol-implanted Soay ewe lambs from 21 September (aged 21 weeks) had restricted (liveweight maintenance) (n = 4) or unrestricted food (n = 4); ovary-intact lambs had unrestricted food (n = 8). LH activation in ovariectomized lambs on restricted and unrestricted food and onset of ovulatory cycles in ovary-intact lambs all occurred on 7 December (SED 8.8 days) (32 weeks), but at different liveweights (24.2, 17.9 and 18.3 kg, respectively, SED 1.22). LH pulse frequency was similar in ovariectomized lambs on restricted and unrestricted food. From 29 August (aged 18 weeks), Soay ewe lambs in seasonally advanced decreased artificial daylength were given restricted food, unrestricted food, or food was restricted for 8 weeks and then unrestricted (n = 8 per group). Ovarian cycles started 3 weeks earlier than in lambs in natural photoperiod on similar dates for all three groups (14, 18 and 19 November, respectively, SED 5.5 days) (29 weeks), but at different liveweights (16.2, 20.7, and 18.4 kg, respectively, SED 0.87). From 1 August, Suffolk x Greyface ewe lambs (aged 16 weeks) had restricted food, unrestricted food, or food restricted for 8 weeks and then unrestricted (n = 8 per group). By 1 November (29 weeks), 0/8 lambs on restricted food (29.3 +/- 0.92 kg) but 8/8 lambs on unrestricted food an 5/8 lambs on 8 weeks of restricted food had ovulated (mean dates: 16 October +/- 2.5 days (27 weeks, 40.1 +/- 1.02 kg), and 1 November +/- 3.0 days (29 weeks, 35.5 +/- 1.23 kg), respectively. Thus, nutritional growth restriction during the 11 weeks preceding normal puberty delayed pubertal data in the improved breed but did not influence the timing of puberty in the unimproved Soay breed within the weight range studied.

Animal Nutritional Physiological Phenomena↗

PubMed2007

Down-regulation of the cardiac sarcoplasmic reticulum ryanodine channel in severely food-restricted rats.

We have shown that myocardial dysfunction induced by food restriction is related to calcium handling. Although cardiac function is depressed in food-restricted animals, there is limited information about the molecular mechanisms that lead to this abnormality. The present study evaluated the effects of food restriction on calcium cycling, focusing on sarcoplasmic Ca2+-ATPase (SERCA2), phospholamban (PLB), and ryanodine channel (RYR2) mRNA expressions in rat myocardium. Male Wistar-Kyoto rats, 60 days old, were submitted to ad libitum feeding (control rats) or 50% diet restriction for 90 days. The levels of left ventricle SERCA2, PLB, and RYR2 were measured using semi-quantitative RT-PCR. Body and ventricular weights were reduced in 50% food-restricted animals. RYR2 mRNA was significantly decreased in the left ventricle of the food-restricted group (control = 5.92 +/- 0.48 vs food-restricted group = 4.84 +/- 0.33, P < 0.01). The levels of SERCA2 and PLB mRNA were similar between groups (control = 8.38 +/- 0.44 vs food-restricted group = 7.96 +/- 0.45, and control = 1.52 +/- 0.06 vs food-restricted group = 1.53 +/- 0.10, respectively). Down-regulation of RYR2 mRNA expressions suggests that chronic food restriction promotes abnormalities in sarcoplasmic reticulum Ca2+ release.

Animals↗

PubMed2003

Effects of a carbohydrate-restricted diet on affective responses to acute exercise among physically active participants.

Currently, the carbohydrate-restricted diet is very popular. Atkins' book, Dr. Atkins' Diet Revolution, has sold millions in its more than 25 years of existence. His book promotes the carbohydrate-restricted diet, which focuses on the consumption of proteins and fats as primary calorie and energy sources, while severely restricting carbohydrates. However, when carbohydrates are restricted from the diet, the body's primary energy source is reduced considerably. Therefore, the purpose of this study was to compare the psychological responses to exercise of individuals when on a carbohydrate restrictive diet and when on a noncarbohydrate restrictive diet. For this study, 17 participants practiced a noncarbohydrate-restricted diet for three weeks and the carbohydrate-restricted diet for three weeks, while maintaining previous exercise habits. After each exercise session, the participants completed the Physical Activity Affect Scale, which measures Positive Affect, Negative Affect, Tranquility, and Fatigue. Simple one-way analyses of variance indicated significant treatment differences (ps<.05) relative to Negative Affect, Positive Affect, and Fatigue. The results of the study indicate as predicted, that, when a person restricts carbohydrates from the diet, he will experience more fatigue, more negative affect, and less positive affect in response to exercise than those individuals who are not restricting carbohydrates.

Adult↗

PubMed1991

Compensatory growth following metabolizable protein or energy restrictions in beef steers.

One hundred sixty crossbred steers were used to compare the effects of metabolizable protein and energy restrictions on subsequent compensatory growth. Diets were formulated to impose severe or mild growth restrictions for periods of 77 to 154 d. Steers were realimented on a high-concentrate diet and fed to achieve approximately 1 cm s.c. fat thickness. Finishing performance and carcass characteristics were evaluated relative to unrestricted control animals. All restricted animals, with the exception of those on the mild, brief energy restriction, exhibited compensatory growth relative to controls. A single direct comparison of energy and protein restriction treatments indicated that finishing performance during realimentation was similar for these two groups. Evaluation of the relative effects of protein and energy restriction by multiple linear regression indicated that compensatory growth was influenced by differences in duration or severity of nutrient deprivation to a greater extent for energy-restricted than for protein-restricted steers. Linear contrasts and regression estimates indicated that compensatory growth was influenced more by differences in severity of restriction than by duration of the restriction period.

Animals↗

PubMed2005

An iterative procedure for deriving selection indexes with constant restrictions.

The objective of this study was to present an iterative procedure for deriving selection indexes with constant restrictions. Constant restriction means that the genetic responses of the restricted traits are preset to actual amounts for a given selection intensity (ī). Results of this study show that an index with constant restriction alone or in combination with other types of restrictions possesses three distinctive characteristics: 1) the coefficient matrix of the index equations is not symmetric and is nonlinear; 2) the coefficient matrix contains unknown ī, indicating that the index coefficients (b) to be derived depends on the value of ī predetermined before selection; and 3) the coefficient matrix contains unknown b, thus requiring iterative methods to solve the index equations. As a result of these unique characteristics, the index coefficients, genetic responses of the index traits, and overall genetic gain in net merit change nonlinearly with varying levels of ī, which is in sharp contrast to both unrestricted and restricted indexes reported in the literature. The construction of a constant-restricted index requires predetermining the value of ī intended for a selection program to derive the corresponding b. An index with constant restrictions has no meaning unless it is associated with a specific value of ī. Numerical examples are given to illustrate the construction of the index with constant restrictions and to validate the theoretical development proposed. The derived equations have yielded an index that maximized the total merit and fulfilled constant restriction at the same time.

Animals↗

PubMed2006

Metabolic effects of abomasal L-carnitine infusion and feed restriction in lactating Holstein cows.

L-Carnitine is required for mitochondrial fatty acid oxidation, but the effects of carnitine supplementation on nutrient metabolism during dry matter intake depression have not been determined in dairy cows. Studies in other species have revealed responses to L-carnitine that may be of specific benefit to dairy cows during the periparturient period. Eight lactating Holstein cows (132 +/- 36 d in milk) were used in a replicated 4 x 4 Latin square experiment with 14-d periods. Treatments were factorial combinations of abomasal infusion of either water or L-carnitine (20 g/d; d 5 to 14) and either ad libitum or restricted intake (50% of previous 5-d dry matter intake; d 10 to 14) of a balanced lactation diet. Liver and muscle biopsies were obtained on d 14 of each period. Feed restriction induced negative balances of energy and metabolizable protein. In feed-restricted cows, carnitine infusion increased 3.5% fat-corrected milk yield compared with those infused with water. Total carnitine concentration in liver was increased in feed-restricted cows infused with carnitine but not in feed-restricted cows infused with water. Carnitine infusion stimulated in vitro oxidation of [1-(14)C] palmitate to acid-soluble products and decreased the proportion of [1-(14)C] palmitate that was converted to esterified products by liver slices. Feed-restricted cows infused with carnitine had lower liver total lipid concentration and tended to have decreased triglyceride accumulation compared with feed-restricted cows infused with water. Plasma nonesterified fatty acid concentration was not altered by carnitine infusion but was increased by feed restriction; serum beta-hydroxybutyric acid was increased by carnitine infusion in feed-restricted cows. In cows fed for ad libitum intake, carnitine infusion affected beta-hydroxybutyric acid, insulin, and urea N in serum, liver glycogen concentration, and in vitro alanine oxidation by liver slices, suggesting that hepatic and peripheral nutrient metabolism was influenced. L-Carnitine infusion effectively decreased liver lipid accumulation during feed restriction as a result of greater capacity for hepatic fatty acid oxidation. Further research examining dietary supplementation of L-carnitine during the periparturient period is warranted.

Abomasum↗

PubMed1992

Effect of early feed restriction on growth, feed conversion, and mortality in broiler chickens.

Two floor pen and two battery experiments were conducted to determine the effects of early feed restriction on the performance of commercial broilers. Feed restriction was induced in all experiments by providing chicks with 40 kcal of ME per bird per day, commencing at 4 days of age. Male chicks were feed-restricted for 7 (Experiments 1 and 2) or 6 days (Experiments 3 and 4), whereas broiler females were restricted for 5 days (Experiment 1). Ad libitum feeding was resumed after the restriction periods, and continued through the conclusion of the experiments at 49 (Experiments 1 and 2) or 28 (Experiments 3 and 4) days of age. Broilers provided ad libitum access to feed for the entire experimental period served as the controls in each study. Broilers subjected to an early feed restriction had significantly (p less than or equal to .05) lower mean body weights than controls for all ages measured in the four experiments. However, feed conversion ratios for restricted broilers were significantly lower at 28 (Experiments 1 through 4) and 49 (Experiments 1 and 2) days of age than for birds consuming feed ad libitum. Through regression analyses, it was estimated that male broilers in Experiments 1 and 2 would require approximately 2 additional days to obtain body weights similar to those observed in control broilers and would still maintain a lower feed conversion ratio at this older age. In Experiments 1 and 2, weekly body weight gains for restricted broilers were significantly lower than for controls from 0 through 28 days of age. However, restricted broilers (7 days) in Experiment 2 had significantly higher rates of gain from 29 to 49 days of age than unrestricted controls. Total pen body weights for restricted and ad libitum groups were similar at 49 days of age in Experiments 1 and 2, which reflected the significant difference in mortality observed between the two groups.

Age Factors↗