Effect Of Feeding Schedule Research Articles

Effect of Feeding Schedule on Carcass Component Weight of Female Kacang Goats

This research was conducted at the Research Barn in Pengawu Village, South Palu Subdistrict, Palu City, Central Sulawesi Province, for 10 weeks, starting from May 19, 2014, to August 11, 2014. The aim of this study was to determine the carcass component weight of female Kacang goats fed at different times. Fifteen female Kacang goats, aged approximately 10 to 12 months and weighing between 10.20 to 16.00 kg, were used for the study. These goats were sourced from local farmers in Palu City and its surrounding areas. Each goat was placed in an individual pen with dimensions of 75 x 75 x 75 cm, and there was a total of 15 individual pens, each equipped with a feeding and drinking trough. The study used a Randomized Block Design (RBD) with five treatments and three blocks as replications. The five different feeding times were as follows: WM1 = Feeding at 08:00 WITA, WM2 = Feeding at 09:30 WITA, WM3 = Feeding at 11:00 WITA, WM4 = Feeding at 12:30 WITA, and WM5 = Feeding at 14:00 WITA. The results of the analysis of variance (ANOVA) showed that feeding at different times had a highly significant effect (P<0.01) on the carcass weight of female Kacang goats in the neck, ribs, and legs. It also had a significant effect (P<0.05) on the carcass component weight in the shoulder, loin, flank, and breast, but it did not have a significant effect (P>0.05) on the carcass component weight in the arm

Anticipation of Scheduled Feeding in BTBR Mice Reveals Independence and Interactions Between the Light- and Food-Entrainable Circadian Clocks.

Many animal species exhibit food-anticipatory activity (FAA) when fed at a fixed time of the day. FAA exhibits properties of a daily rhythm controlled by food-entrainable circadian oscillators (FEOs). Lesion studies indicate that FEOs are separate from the light-entrainable circadian pacemaker (LEP) located in the suprachiasmatic nucleus. While anatomically distinct, food- and light-entrainable clocks do appear to interact, and the output of these clocks may be modulated by their phase relation. We report here an analysis of FAA in the BTBR T+ Itpr3tf/J (BTBR) mouse strain that provides new insights into the nature of interactions between food- and light-entrained clocks and rhythms. BTBR mice fed ad libitum exhibit an unusually short active phase and free-running circadian periodicity (~22.5 h). In a light-dark cycle, BTBR mice limited to a 4 h daily meal in the light period show robust FAA compared to the C57BL/6J mice. In constant darkness, BTBR mice exhibit clear and distinct free-running and food-anticipatory rhythms that interact in a phase-dependent fashion. The free-running rhythm exhibits phase advances when FAA occurs in the mid-to-late rest phase of the free run, and phase delays when FAA occurs in the late active phase. A phase-response curve (PRC) inferred from these shifts is similar to the PRC for activity-induced phase shifts in nocturnal rodents, suggesting that the effects of feeding schedules on the LEP in constant darkness are mediated by FAA. A phase-dependent effect of the free-running rhythm on FAA was evident in both its magnitude and duration; FAA counts were greatest when FAA occurred during the active phase of the free-running rhythm. The LEP inhibited FAA when FAA occurred at the end of the subjective day. These findings provide evidence for interactions between food- and light-entrainable circadian clocks and rhythms and demonstrate the utility of the BTBR mouse model in probing these interactions.

Automated feeding systems for shrimp: Effects of feeding schedules and passive feedback feeding systems

Shrimp aquaculture has been on a growing trend for the past four decades and its continued success will rely on efficient feeding protocols and reductions in labor cost. Various studies have demonstrated better growth and feed conversion for shrimp fed numerous meals in opposition to the traditional 1 to 4 meals offered during the day. With the adoption of automatic feeding systems by the shrimp industry not only can more feedings be delivered but also the time of day when feed is delivered is less problematic. This opens the door to looking at various feed management strategies. The goal of this work was to continue the development of a standard feeding protocol for timer feeders (SPTF) to maximize growth rates and production efficiency in semi-intensive pond production of shrimp through manipulation of feeding schedules. For this work, a 13-week pond production trial was performed in 16, 0.1 ha outdoors ponds, stocked at 35 shrimp/m2. Four treatments including: three fixed feeding treatments based on SPTF Day, SPTF Night and SPTF 115% 24 h were offered using automatic timer-feeders, and a fourth on demand treatment utilized AQ1 acoustic feeding system. To further evaluate different combinations of number of meals, feed quantities and time of feeding, a 11-week growth trial was conducted in 32, 800 L circular tanks in a recirculating green-water system. Results for the pond trial further confirm higher yields with AQ1 acoustic feeding system and showed no statistical differences among timer feeder treatments. Results in the tank trial indicated a relationship between growth response to increasing feed inputs and number of meals rather than feeding schedule alone. We also observed in the same trial a positive response on growth to more meals for identical feeding rates. Results confirm that increasing the number of feeding allows increased feed inputs and thus increased growth. The on demand feeding protocol using passive acoustics, resulted in the best performance of the shrimp.

10.4314/sajas.v40i5.65325

The effect of the feeding schedule and the use of a dditives on the intake and its rate were studied on animals consuming a temperate pasture. Twenty four wethers (47.8 ± 6.4 kg BW), housed in metabolism cages, were fed a fresh pasture (80% Lotus corniculatus ) and assigned to four groups. Group AD had forage available all day; group 1D was fed for 6 h/day; gr oup 1D&B was fed 6 h/day plus 2% DM intake level of buffer (75% NaHCO 3-25% MgO) and group 1D&S was fed 6 h/day plus 6.2 x 10 9 CFU/animal/day of Saccharomyces cerevisiae. Daily intake and its rate were measured weighing t he amount offered and refused every one hour for six hours. Orthogonal contrasts were performed on data to study the effect of feedi ng schedule, the use of additives and the type of addi tive used. There were no differences in g of DM ingested/kg BW 0.75 /day (mean value: 52.8). Groups fed 6 h/day showed a higher rate of intake for every hour studied (i.e. hour 2: AD: 5.9 vs. 6 h/day: 7.2). Within groups fed 6 h/day plus the buffer supplemented one presented the highest cumulative intake, at 20.9 g DMi/kg BW.

Impact of Feeding Schedule on the Growth Performances of Tilapia, Common Carp, and Rice Yield in an Integrated Rice-Fish Farming System

Feeding frequency, among various factors, greatly influences the production costs of aquaculture. In the present investigation, the effects of feeding schedule on the growth and production of tilapia and common carp were evaluated, along with rice yield, in an integrated rice-fish culture system. The experiment comprised 11 treatments, each with three replications, and a control treatment with no fish (T0). The fish in treatments T1–T5 were fed with rice bran once per week at 09:00 for T1, two days per week at 12:00 for T2, three days per week at 15:00 for T3, four days per week at 18:00 for T4, and five days per week at 09:00 and 18:00 for T5. The fish in treatments T6–T10 were fed an artificial floating feed with the same scheduled feeding frequency as T1–T5. The highest specific growth rate (SGR) in common carp (2.4%) and tilapia (4.3%) was found in T10. Similarly, the highest weight gains of tilapia (322.7 g) and common carp (180.9 g) were observed in T10 after 75 days of culture. In terms of rice, however, the highest recorded grain, straw, and biological yields of 5.6, 6.8, and 12.3 t ha−1, respectively, were observed for control T0. Overall, the highest net return (USD 30,051 ha−1) was found in T10. There was a 1504% greater net return and 98% higher benefit–cost ratio (BCR) in T10 compared to the control (T0). Five days of feeding per week at 09:00 and 18:00 was found to be the feeding schedule that resulted in the highest economic net return of those tested.

Effect of feeding schedule on time to reach full feeds in neonates weighing 500 to 1500 grams: A randomized trial

Effect of feeding schedule on time to reach full feeds in neonates weighing 500 to 1500 grams: A randomized trial

Influence of feeding schedules on the chronobiology of renin activity, urinary electrolytes and blood pressure in dogs

The contribution of the renin–angiotensin–aldosterone system (RAAS) to the development of congestive heart failure (CHF) and hypertension (HT) has long been recognized. Medications that are commonly used in the course of CHF and HT are most often given with morning food for the sake of convenience and therapeutic compliance. However, biological rhythms and their responsiveness to environmental clues such as food intake may noticeably impact the effectiveness of drugs used in the management of cardiovascular disorders. Only sparse information about the effect of feeding schedules on the biology of the RAAS and blood pressure (BP) is presently available. Two studies were designed to explore the chronobiology of renin activity (RA), BP, renal sodium (UNa,fe) and potassium (UK,fe) handling in relation to meal timing in dogs. In a first experiment (Study a), blood and urinary samples for measurement of RA, UNa,fe and UK,fe were drawn from 18 healthy beagle dogs fed a normal-sodium diet at either 07:00, 13:00 or 19:00 h. In a second experiment (Study b), BP was recorded continuously from six healthy, telemetered beagle dogs fed a similar diet at 07:00, or 19:00 h. Data were collected throughout 24-h time periods, and analyzed by means of nonlinear mixed-effects models. Differences between the geometric means of early versus late time after feeding observations were further compared using parametric statistics. In agreement with our previous investigations, the results indicate that RA, UNa,fe, UK,fe, systolic, and diastolic BP oscillate with a circadian periodicity in dogs fed a regular diet at 07:00 h. A cosine model with a fixed 24-h period was found to fit the variations of RA, UK,fe and BP well, whereas cyclic changes in UNa,fe were best characterized by means of a combined cosine and surge model, reflecting a postprandial sodium excretion followed by a monotonous decay. Our data show that feeding time has a marked influence on the chronobiology of the renin cascade, urinary electrolytes, and BP. Introducing a 6- or 12-h delay in the dogs’ feeding schedule caused a shift of similar magnitude (05:06 and 12:32 h for Studies a and b, respectively) in the rhythm of these biomarkers. In all study groups, RA and BP exhibited a marked fall just after food intake. The drop in RA is consistent with sodium and water-induced body fluid expansion, while the reduction of BP could be related to the decreased activity of renin and the secretion of vasodilatory gut peptides. An approximately 1.5-fold (1.2–1.6-fold) change between the average early and late time after feeding observations was found for RA (p < 0.0001), UNa,fe (p < 0.01) and UK,fe (p < 0.05). Postprandial variations in BP, albeit small (ca. 10 mmHg), were statistically significant (p < 0.01) and supported by the model-based analysis.In conclusion, the timing of food intake appears to be pivotal to the circadian organization of the renin cascade and BP. This synchronizing effect could be mediated by feeding-related signals, such as dietary sodium, capable of entraining circadian oscillators downstream of the master, light–dark-adjusted pacemaker in the suprachiasmatic nucleus.

Influence of time of food administration on daily rhythm of total locomotor activity in ponies

The activity rhythm can be entrained by nonphotic cues, especially food availability. Daily feeding schedules can act as “Zeitgeber” to synchronize the circadian system. In this study, the authors evaluated the influence of different feeding schedules on the daily rhythm of total locomotor activity in ponies. Six clinically healthy Shetland ponies were kept under natural 12/12-h light/dark cycle and monitored during 4 different feeding schedules: fed twice (at 8 am and 8 pm ), fasted, fed at 8 pm , fed at 8 am , and fed twice a day again. Water was available ad libitum. To record total activity, we equipped the animals with actigraphy-based data loggers (Actiwatch-Mini). Two-way analysis of variance revealed a significant main effect of the time of day and no effect of feeding schedules on the amount of total locomotor activity. Locomotor activity showed daily rhythmicity in all experimental conditions, with diurnal acrophase. The amplitude of the rhythms and their robustness statistically changed across all experimental conditions. Our findings support the theory that when given essentially free choice hay, the time of feeding did not entrain activity, and suggest that feeding behavior can influence the distribution of locomotor activity during a 24-hour period in ponies, with changes in the amplitude and robustness of the rhythm.

Effects of Feeding Schedules on Development and Maintenance of Fat Binge Eating in Rats

Effects of Feeding Schedules on Development and Maintenance of Fat Binge Eating in Rats

Effects of feeding schedule on locomotor activity rhythms and stress response in sea bream

Feeding cycles entrain biological rhythms, which enable animals to anticipate feeding times and so maximize food utilization and welfare. In this article, the effect of mealtime was investigated in two groups of sea bream ( Sparus aurata): one group received a single daily meal at random times during the light period (random daytime feeding, RDF), whereas the other group received the meal during the light period but at the same time (scheduled daytime feeding, SDF). All the fish showed diurnal behavior, although the SDF group showed a lower percentage of diurnalism (84.4% vs. 79.5% in RDF and SDF respectively) and developed food anticipatory activity some hours before the mealtime. In addition, the mean daily locomotor activity of the RDF group was significantly higher than that of the SDF group (3132 vs. 2654 counts/day, respectively). Although the mean weight differed between both groups on day 30 (115.7 g and 125.6 g in RDF and SDF respectively), these differences had disappeared by day 60. Plasma cortisol and glucose significantly differed in both groups (cortisol: 71.8 vs. 8.7 ng/ml, glucose: 53.7 vs. 43.8 mg/dl in RDF and SDF, respectively), whereas lactate did not differ significantly. The results obtained suggest that altering the feeding time (scheduled vs. random) affects the behavior and physiology of sea bream, indicating that a single daily feeding cycle (compared to random) is beneficial for fish welfare because they can prepare themselves for the forthcoming feed.

Effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group-housed sows1,2

A total of 208 sows and 288 gilts (PIC line C29) were used to determine the influence of feeding frequency (2 vs. 6 times/d, floor fed) on performance and welfare measurements on a commercial sow farm. Treatments consisted of feeding similar amounts of feed to each sow (2.5 kg) or gilt (2.05 kg) over 2 (0700 and 1530) or 6 times daily (0700, 0730, 0800, 1530, 1600, and 1630). There were 8 sows or 12 gilts in each pen. Gilts and sows were moved to pens 1 to 4 d after breeding. In sows, there were no differences (P > 0.10) in ADG, backfat change, or variation in BW. There was a trend (P < 0.08) for sows fed twice daily to farrow more total pigs born, but number born alive or other reproductive performance traits were not different (P > 0.10) among treatments. Sows fed 6 times per day had increased vocalization during the morning (P < 0.07) and afternoon (P < 0.01) feeding periods compared with sows fed twice daily. Sows fed twice daily had more skin (P < 0.01) and vulva (P < 0.04) lesions as well as a small increase in feet and leg (P < 0.01) and hoof (P < 0.02) problems. In this commercial facility, the standard management protocol required moving gilts to a different gestation facility on d 42. On d 42, two pens of gilts with similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. Gilts fed 6 times daily had a tendency for greater ADG (P < 0.07) from d 0 to 42 and a tendency for greater (P < 0.09) backfat on d 42. After movement to the larger groups from d 42 to farrowing, ADG was similar (P > 0.10) for gilts fed 2 or 6 times daily. Gilts fed twice daily had lower BW variation at d 42 (P < 0.04) and tended to at farrowing (P < 0.10). In gilts, there were no differences (P > 0.10) for reproductive performance, skin and vulva lesions, and feet and leg scores. In conclusion, there were few growth, farrowing, or aggression differences among gilts fed 2 or 6 times daily. This suggests that either feeding method is suitable for group-housed gilts. Among sows, feeding frequency resulted in few growth or farrowing performance differences. Feeding 6 times daily resulted in a small but significant reduction in skin and vulva lesions and structural problem scores while increasing vocalization. Increasing the feeding frequency from 2 to 6 times daily does not appear to have a negative or positive impact on performance or welfare of group-housed gilts and sows.

Investigation into the effects of feeding schedule on body condition, aggressiveness, and reproductive failure in group housed sows (2006)

A total of 208 sows and 288 gilts (PIC Line C29) were used to determine the influence of feeding frequency (2 versus 6 times per day) in gestation on performance and welfare measurements. The experiment was conducted on a commercial sow farm in northeast Kansas that typically housed gestating sows and gilts in pens. Treatments consisted of feeding similar amounts of feed to each sow or gilt over 2 (07:00 and 15:30) or 6 meals per day (07:00, 07:30, 08:00, 15:30, 16:00, and 16:30 hours). There were 8 sows or 12 gilts in each pen. Gilts and sows were moved to pens after breeding. In gestating sows, there were no differences (P>0.10) between treatments in ADG, backfat change, or variation in body weight. There was a trend (P<0.08) for sows fed twice a day to farrow more total number born, but number born alive or other measures of reproductive performance were not different (P>0.10) among treatments. Sows fed 6 times a day had increased vocalization during the morning (P<0.07) and afternoon (P<0.01) feeding periods, compared with sows fed twice a day, but sows fed twice a day had more skin (P<0.01) and vulva (P<0.04) lesions, as well as a small, but significant, increase in feet/leg (P<0.01) and hoof (P<0.02) problems. In this commercial facility, the standard management protocol required moving gilts to a different gestation facility. On d 42, two pens of gilts with similar breeding dates and treatment were combined and moved to another facility with larger pens until farrowing. From d 0 to 42, gilts fed 6 times a day had greater ADG (P<0.07) and d-42 backfat (P<0.09). After movement to the larger groups from d 42 to farrowing, ADG was similar (P > 0.10) for gilts fed 2 or 6 times per day. Gilts fed twice a day had less weight variation at both d 42 (P<0.04) and at farrowing (P<0.10). In gilts, there were no differences (P>0.10) for reproductive performance, skin and vulva lesions, and leg/feet and hoof scores. In conclusion, there were few growth, farrowing, or aggression differences among gilts fed either 2 or 6 times per day. This suggests that either feeding method is suitable for group-housed gilts. Among sows, different feeding frequency resulted in few growth or farrowing-performance differences. Feeding 6 times per day did result in a small, but significant, reduction in skin and vulva lesions and structural-problem scores, while increasing vocalization.

Effect of Feeding Schedule on Ammonia Emission from Individual and Group-housing Systems for Sows

The effect of feeding schedule on ammonia emission from housing systems for sows was studied. The hypothesis was that changing the feeding schedule would change the diurnal pattern of the ammonia emission and that daytime feeding would cause more ammonia to be emitted from the manure compared to evening feeding. The experimental units were an individual housing system with 64 dry sows in stalls (system A) and two group-housing systems: system B with 62 dry sows and feeding stalls and system C with 65 dry sows and electronic sow feeders (ESFs). In systems A and B, the sows were fed simultaneously twice daily. In system C, the sows were fed sequentially once a day. During feeding schedule 1, feeding times in systems A and B were 7:30 and 15:30 h, in system C feed was available from 15:30 h on. During schedule 2, feeding times in systems A and B were 7:30 and 21:30 h, in system C food was available from 7:30 h on. Ammonia emission, indoor temperature and animal activity were measured and the data were analysed considering autocorrelations with a time-series model. The values for the coefficients of determinations R 2 of the models explaining ammonia emission by indoor temperature and animal activity were 48% for system A, 66% for system B and 64% for system C. In all three systems, the diurnal patterns of the indoor temperature, animal activity and ammonia emission changed considerably with the feeding schedule. Average ammonia emissions per sow for feeding schedules 1 and 2 were, respectively, 0·71 and 0·68 g h −1 (probability P=0·23) from system A, 0·60 and 0·61 g h −1 ( P=0·75) from system B and 0·69 and 0·76 g h −1 ( P<0·01) from system C. It can be concluded that changing the feeding schedule alters the diurnal pattern of the ammonia emission, but if the animals are fed simultaneously, changing the feeding time does not affect the total amount of ammonia emitted. However, with the animals fed sequentially, the ammonia emission falls by 10% if the feeding starts in the afternoon instead of in the morning.

Effect of Feeding Schedule and Feeding Rate on Size and Number of Adipocytes in Rainbow Trout Oncorhynchus mykiss

Effect of Feeding Schedule and Feeding Rate on Size and Number of Adipocytes in Rainbow Trout <i>Oncorhynchus mykiss</i>

Effect of feeding schedule on growth of rainbow trout

Rainbow trout (Oncorhynchus mykiss) fingerlings were reared for 2 months under one of two different feeding regimes (‘one and two diurnal peaks’) and under a constant feeding regime as a control in order to find out if it is possible to fit the feeding to the assumed circadian rhythm. The differences in the specific growth rates observed between the different feeding treatments were not significant, but the ‘tank-effect’ and the effect of the genetic background of the fish were highly significant. The conclusion that no beneficial effects are achievable through alteration of the feeding regime and the significance of a possible genotype-feeding-regime interaction are discussed.

Systemic Responses to Different Enteral Feeding Schedules in Rats

The purpose of this study was to describe selected temporal systemic responses to different enteral feeding schedules using an animal model, as one prerequisite for determining optimal delivery times for human enteral feedings. The effect of feeding schedules and time of day were examined relative to body weight and plasma glucose, insulin, glucagon, and corticosterone levels. Adult male Sprague-Dawley rats (N = 80) were used in a 4 x 4 randomized block design. Rats started the feeding schedules on Day 11 post-gastrostomy tube placement. The following feeding schedules, often used by humans, were tested: 24-hour enteral; 24-hour oral; 12-hour (rest time) enteral; and 12-hour (rest time) oral. Plasma was collected on Day 20. Despite very different feeding schedules, there were no statistical differences in weight gain, or plasma glucose and glucagon levels. Levels of insulin and corticosterone were significantly influenced by time of day and/or feeding group. Temporal pattern disruption was greatest in the rest-time fed enteral group. Both route and timing of enteral delivery modified metabolic hormone patterns.

Growth of nursery-raised Macaca nemestrina infants: Effects of feeding schedules, sex, and birth weight.

Ponderal growth, caloric intake, growth velocity, and growth efficiency were studied from birth through 90 days in 523 nursery-raised pigtailed macaque infants. The male and female subjects ranged in birth weight from the 1st through 100th centiles of the colony distribution and were all judged to be clinically healthy. One group of infants was fed on an ad lib schedule, with formula continuously available from dispensers which were replenished every 8 h. A second group was fed on a distributed regimen, with formula available on a 4-h-on/4-h-off schedule. The latter schedule was instituted because of bacterial growth in the milk after 4 h. Infants fed the distributed diet had 20-25% lower caloric intake than those fed ad lib, but equaled or exceeded ad lib infants in body weight, growth velocity, and grams gained per 100 kilocalories (growth efficiency). The poorer utilization of calories by the ad lib group was attributed to a combination of bacteria in the milk, which caused diarrhea, and inability to metabolize the excess nutrients gained from overconsumption of fluids. The effects of the distributed diet occurred for both males and females, and across the full range of birth weights. Peak velocity and growth efficiency for both males and females occurred at 2 weeks after birth for high-birth-weight (HBW) infants and at 3 weeks for low-birth-weight (LBW) infants. However, the growth efficiency of LBW infants was equal to, or greater than, that of HBW infants after postnatal day 2. Descriptive statistics and regression equations based on this large sample are presented for quantitative comparisons of growth parameters with those of other primate species reared in laboratory or field settings. © 1992 Wiley-Liss, Inc.

Effects of feeding schedules on diurnal periodicity of Leucocytozoon smithi gametocytes in the peripheral blood of domestic turkeys.

Eighteen domestic turkeys naturally infected with Leucocytozoon smithi Laveran & Lucet were maintained on restricted feeding schedules under conditions of either continuous light or natural light (light 13 h:darkness 11 h) photoperiods. Peripheral gametocyte numbers of L. smithi in all turkeys were determined every 2 h over a 36-h period. Peripheral gametocyte numbers of turkeys maintained under continuous light and restricted to either a 10-h feeding period (9:30 p.m. to 7:30 a.m.) once a day or a 2-h feeding period twice a day (7:30 a.m. to 9:30 p.m. and 7:30 p.m. to 9:30 p.m.) increased at or near the time of feed availability. Under natural photoperiod, gametocyte periodicity was not affected by restricting feed availability to the dark phase of the light-dark cycle. Mean parasite numbers were highest during the light phase when feed was not available, and lowest during the dark period when feed was accessible.

Sleep patterns of the laboratory cat

The effects of feeding schedule and external stimuli on sleep patterns were investigated in cats fed to maintain their mean body weight. The ECoG, EOG and EMG were recorded from 3 male cats fed once daily and under a 12 : 12 light-dark schedule. The results for 15 working days were compared with those obtained at week-ends and under continuous lighting, fasting, reduced food intake or overfeeding. Feeding was also divided into 3 meals per day. Despite some differences in their responsiveness. All cats exhibited the usual values for the critical variables of SWS: diurnal placement, intermittency and total amount. A low percentage of PS per 24 h was recorded. This was related both to the restricted amount of food eaten and to the feeding schedule. Reduced external stimuli at week-ends resulted in concentration of sleep during daytime, whereas sleep was reduced during continuous lighting in conjunction with an increased percentage of drowsiness. The most marked effect of fasting (pig fat) was fragmentation of sleep episodes. Divided meals and an increased food intake both increased the total sleep duration. It is suggested that the restricted amount of food and relatively enriched environment used, accompanied by a reduced sleep duration, may be comparable to that seen in free animals. Sleep patterns in the cat are very responsive to light-dark schedule, reduced external stimuli and fasting.

Diurnal Patterns of DNA Synthesis in the Rat: Modification by Diet and Feeding Schedule

The diurnal pattern of DNA synthesis in young rats (28 to 35 days) was investigated under various feeding regimens of a normal and a protein-deficient diet. All animals were exposed to a 12-hour lightâ€12-hour dark cycle. With ad libitmn feeding of a stock diet, the incorporation of thymidine-'H into nuclear DNA in liver varied over a fivefold range with a peak at the end of the dark period, whereas incor poration into mitochondrial DNA scarcely varied. A diet deficient in protein (3.5% protein) not only decreased the incorporation of thymidine-'H into liver DNA but also obscured the diurnal peaks observed in animals fed a diet containing 26% protein. The activity of thymidine kinase was also depressed, but the diurnal peak was still discern ible though slightly delayed. The effect of feeding schedule was then studied by re stricting the feeding period of a stock diet to either the first 8 hours of the dark period (close to normal feeding behavior) or to the first 8 hours of light. The 12-hour differ ence in the feeding period resulted in a closely corresponding difference in the timing of the peak incorporation of thymidine-'H into DNA. In rats gradually adapted to a 4-hour feeding schedule over a period of 10 days, there was a briefer but prominent peak of incorporation about 12 hours after the onset of feeding. A smaller peak was concurrently present in the adrenals but in skeletal muscle, intestinal mucosa and bone marrow there was no clear pattern of deviation from the 24-hour mean values. The results indicate that 1) in contrast to nuclear DNA, there is no prominent diurnal peak of mitochondrial DNA synthesis in liver; 2) the peak of nuclear DNA synthesis in liver is obscured by a protein-deficient diet; 3) the peak follows feeding of a normal diet by about 12 hours, independently of the lightâ€dark cycle; and 4) with the exception of the adrenals, other tissues studied did not reveal a food-dependent peak of DNA syn thesis. J. Nutr. 104: 1234â€1241,1974.