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Background: The impact of temporal feeding patterns remains a major unanswered question in nutritional science. Progress has been hampered by the absence of a reliable method to impose temporal feeding in laboratory rodents, without the confounding influence of food-hoarding behavior.Objective: The aim of this study was to develop and validate a reliable method for supplying crushed diets to laboratory rodents in consistent, relevant feeding patterns for prolonged periods.Methods: We programmed our experimental feeding station to deliver a standard diet [StD; Atwater Fuel Energy (AFE) 13.9% fat] or high-fat diet (HFD; AFE 45% fat) during nocturnal grazing [providing 1/24th of the total daily food intake (tdF/I) of ad libitum-fed controls every 30 min] and meal-fed (3 × 1-h periods of ad libitum feeding) patterns in male rats (Sprague-Dawley: 4 wk old, 72-119 g) and mice [C57/Bl6J wild-type (WT): 6 mo old, 29-37 g], and ghrelin-null littermates (Ghr-/-; 27-34 g).Results: Grazing yielded accurate, consistent feeding events in rats, with an approximately linear rise in nocturnal cumulative food intake [tdF/I (StD): 97.4 ± 1.5% accurate compared with manual measurement; R2 = 0.86; tdF/I (HFD): 99.0 ± 1.4% accurate; R2 = 0.86]. Meal-feeding produced 3 nocturnal meals of equal size and duration in StD-fed rats (tdF/I: 97.4 ± 0.9% accurate; R2 = 0.90), whereas the second meal size increased progressively in HFD-fed rats (44% higher on day 35 than on day 14; P < 0.01). Importantly, cumulative food intake in grazing and meal-fed rats was identical. Similar results were obtained in WT mice except that less restricted grazing induced hyperphagia (compared with meal-fed WT mice; P < 0.05 from day 1). This difference was abolished in Ghr-/- mice, with meal initiation delayed and meal duration enhanced. Neither pattern elevated corticosterone secretion in rats, but meal-feeding aligned ultradian pulses.Conclusions: We have established a consistent, measurable, researcher-defined, stress-free method for imposing temporal feeding patterns in rats and mice. This approach will facilitate progress in understanding the physiologic impact of feeding patterns. [ABSTRACT FROM AUTHOR]

Involvement of the caudal raphe nuclei (raphe pallidus, RPa; raphe magnus, RMg, and raphe obscurus, ROb) in feeding behavior of adult rats was studied by measuring c-Fos protein expression, in animals submitted to the "meal-feeding" model of food restriction in which the rats were fed ad libitum only from 7:00 to 9:00 h, for 15 days. The experimental groups submitted to chronic fasting, named 'search for food' (SF), 'ingestion of food' (IF) and 'satiety of food' (SaF) were scheduled after a previous study in which the body weight and the general and feeding behaviors were evaluated by daily monitoring. Acute, 48-h fasting (AF) was used as control. In the chronic group, the animals presented a 16% reduction in body weight in the first week, followed by a continuous, slow rise in weight over the subsequent days. Entrainment of the sleep-wake cycle to the schedule of food presentation was also observed. The RPa was the most Fos immunopositive nucleus in the chronic fasting group, followed by the RMg. The ANOVA and Tukey test (P

Diurnal patterns and time courses of activity were investigated in groups of fast-growing broilers subjected to different levels of qualitative and quantitative feed restrictions. Eight groups of 225 female Ross 208 broiler chickens were reared from 1 to 57 days of age in straw-bedded floor pens (18.9 m2) equipped with drinking nipples and six circular feed troughs. The lighting schedule consisted of 7 h and 10 min of darkness preceded by 30 min dusk. Groups were fed one of two feeds (Control and Diluted), where the latter was the Control feed Diluted with 15% ground oat hulls. All groups were fed ad libitum between 0–7 days of age and 43–56 days of age. During the in-between period four groups were fed ad libitum and four groups were fed twice a day (meal-fed). The meal-fed groups were fed 58 and 67% of the ad libitum groups on Control and Diluted, respectively, calculated on a weekly basis. Activity was logged every half-a-minute throughout the experimental period using passive infrared detection (PID). Number of birds feeding was counted in all groups every 4 min during 90 min after the morning meal (08.00 h) and 90 min around the afternoon meal (14.00 h). Quantitative, but not qualitative, feed restriction affected activity levels, with meal-fed chickens being more active throughout the light period. An increase in the proportion of meal-fed birds observed feeding following each meal was reflected in the PID activity data. Across the meal-feeding period the meal-fed chickens appeared to learn about food availability and adjusted their behaviour accordingly. General activity of the chickens peaked at 21 days for all groups. An activity increase during the dark period was found to reflect night feeding as well as the growth of the birds. The potential welfare benefit to the birds of increased activity caused by quantitative feed restriction was in the present experiment overshadowed by the concomitant extended periods of hunger. [Copyright &y& Elsevier]

Medaka were maintained on a 16∶8 light-dark cycle and fed once daily on one of 5 different feeding schedules. The daily rhythm of agonistic behavior rapidly entrained to the scheduled feeding time and maintained this entrainment during a 3-day starvation period. In contrast the daily rhythms of egg laying and courtship stayed entrained to the L:D cycle regardless of the feeding schedule. Thus, temporal integration of this fish with its daily environment can involve multistimuli which concurrently and differentially entrain externally expressed circadian systems. [ABSTRACT FROM AUTHOR]

A number of metabolic factors and the activity of a number of enzymes were determined in meal-fed (animals fed a single daily 2 hr meal) and nibbling (ad libitum-fed) rats. The dependency of the observed adaptive changes on the ingestion of carbohydrate was studied by feeding diets high in carbohydrate or fat.Glucose-6-phosphate dehydrogenase and NADP-malic dehydrogenase were more active in adipose tissue from high carbohydrate meal-fed rats than in tissue from ad libitum-fed rats. The activity in adipose tissue of isocitric dehydrogenase, 6-phosphogluconate dehydrogenase, and NAD-malic dehydrogenase did not increase significantly in response to meal-feeding the high carbohydrate diet. No increase in lipogenesis or enzyme activity could be demonstrated in adipose tissue from rats meal-fed a high fat diet. Lipase activity of adipose tissue was increased by high carbohydrate meal-feeding and decreased by feeding a high fat diet. The in vitro uptake of palmitate-1-14C by adipose tissue was depressed by a high fat diet and enhanced in rats meal-fed a high carbohydrate diet. Diaphragm or slices of liver from high fat-fed rats oxidized palmitate-1-14C more rapidly than did tissue from ad libitumfed animals. Evidence is presented for the quantitative importance of citrate as a source of extramitochondrial acetyl CoA in adipose tissue of meal-eating and ad libitum-fed rats. The relationship of extramitochondrially formed citrate to the NAD-malic dehydrogenase–malic enzyme system in adipose tissue is discussed.