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PubMed2006

The effects of glucocorticoids on feeding behavior in rats.

Glucocorticoids have major effects on food intake, however, the underlying mechanisms are poorly understood. This article highlights data on the changes that occur when glucocorticoids are removed by adrenalectomy, and the effects of central and systemic administered glucocorticoids on feeding behavior in rats. Next, animal data on the interaction of glucocorticoids with insulin on intake of comfort foods are addressed and the hypothesis that glucocorticoids modify feeding behavior, whereas insulin modifies the choice of food is discussed. Finally a view is presented that hormonal and vagal signals generated when (comfort) food is consumed will affect the corticotropin-releasing factor (CRF) brain network important for the response to stress and the regulation of feeding. With a society, where stress is experienced daily and comfort food is found at every street corner, it will be vital to understand the interactions between the systems that react to stress and regulate feeding behavior to fight the obesity epidemic.

Adrenalectomy↗

PubMed1993

Pharmacologically induced elements of the hunting and feeding behavior in the pteropod mollusk Clione limacina. II. Effects of physostigmine.

1. A contact of the pteropod mollusk Clione limacina with its prey (small pteropod mollusk Limacina helicina) evokes a complex pattern of hunting and feeding behavior: protraction of tentacles to seize the prey, activation of buccal apparatus to swallow the prey, activation of locomotor system (speeding up of wing beating), reversal of reaction to tactile stimulation of the head, loss of normal (vertical) orientation in space, and swimming in circles. After injection of physostigmine (PhS), the acetylcholinesterase inhibitor, into the hemocoel of intact Clione, all these manifestations of the hunting and feeding behavior could be evoked by tactile stimulation of the head, or they arose spontaneously. 2. In the preparation of the isolated CNS, the effect of PhS on the neural networks controlling different aspects of the hunting and feeding behavior was studied by recording from neurons monitoring activity of different networks (< or = 4 neurons simultaneously). Tactile stimulation of the head was mimicked by a short-term electrical stimulation of the corresponding nerve. Before PhS application, the nerve stimulation evoked elements of the defense reaction, i.e., long-lasting inhibition of all main motor control systems: the locomotor network in the pedal ganglia, the tentacle control network in the cerebral ganglia, and the network controlling radula and hook movements in the buccal ganglia. However, after PhS application, the same stimulus evoked a long-lasting bout of excitation in all the three networks accompanied by activation of the heart-exciting neuron as well as by a modification of the activity of statocyst receptor cells controlling Clione's spatial orientation (the "fictive hunting bout"). Similar hunting bouts could arise spontaneously. 3. Injection of acetylcholine (ACh) into the hemocoel of intact Clione was less effective than injection of PhS. After ACh injection, reversal of reaction to head stimulation was observed in < or = 20% of the experiments (the percentage of positive results was higher if ACh was injected into the head just over the CNS). Bath application of ACh to the isolated CNS did not produce the hunting bouts. However, a short-term local application of ACh to the cerebral ganglia in the isolated CNS resulted in activation of the main motor systems controlling locomotion, protraction of tentacles, and movements of buccal mass. 4. During spontaneous PhS-induced bouts, excitation of different networks involved in hunting behavior was sometimes not quite synchronous. Different networks could be excited in variable order over a period of up to several seconds.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholine↗

PubMed1980

A chronometric approach to the study of feeding behavior.

In many mammalian genera, the stimulus to feed is intimately associated with circadian rhythms. This stimulus arises from within the brain from biological time-keeping systems. Such a chronometric approach to feeding behavior follows from a consideration of the terrestrial mammal's space-time pattern within the ecological niche. The ecological niche is a division of time as well as space. The restriction of certain behaviors to certain times of day and the concomitant evolution of nocturnality or diurnality represent strong advantages for survival in the wild. Experimental data, primarily from studies on the rat, in support of the chronometric approach, include: the reinstatement of cyclic feeding patterns after food deprivation; the continuation of circadian pattern of wheel running and nocturnal drinking during food deprivation; consideration of the ontogeny of the feeding pattern; the phenomenon of anticipatory appetite--the experimental demonstration that time of day can act as a conditioned stimulus for feeding; the evaluation of rhythms in digestion, absorption and assimilatory biochemical processes; the realization that many of these rhythms are not simply a consequence of the presence of food in the gut; the realization that the brain exerts considerable control over the peripheral rhythmic nutritional processes via ANS and endocrinological systems; and the fact that within the brain the SCN and structures well known to be involved in nutritional regulation, such as the VMH, LHA and monoamine systems, may all be involved in the circadian pattern of feeding. Further, the function of these neurological structures may be understood better by consideration of data from temporal changes in feeding patterns.

Amino Acids↗

PubMed2001

Strike feeding behavior in the muskellunge, Esox masquinongy: contributions of the lateral line and visual sensory systems.

The muskellunge, Esox masquinongy, is a predatory esocid fish with well-developed visual and lateral line systems. The purpose of this study was to determine the relative roles of these two sensory modalities in organizing the strike behavior of the animal. Subadult muskellunge were videotaped in a test arena while feeding on fathead minnows (Pimephales promelas). Animals were tested under five conditions: (i) control animals in which the visual and lateral line systems were intact; (ii) animals with lateral line afference suppressed by immersion for 12-24 h in 0.1 mmol l(-1) CoCl2; (iii) animals blinded by bilateral optic nerve transection; (iv) animals that had been unilaterally blinded; and (v) animals in which the lateral line system had been unilaterally denervated. The feeding behavior of the muskellunge consists of two phases: a slow stalk of the prey with minimal body movement followed by an explosive C- or S-start lunge at the prey. Quantitative comparisons of animals in the five test groups indicate that, although vision is used in the initial acquisition of the prey, both vision and the lateral line system play important roles in determining the initiation of the rapid strike. The lateral line system may play a critical role in the final capture of the prey at the end of the strike. In addition, lateral-line-suppressed muskellunge strongly alter their approaches to more distant prey. Bilaterally blinded muskellunge do not stalk their prey, but will lunge only at prey that are at close range. Unilaterally blinded or denervated muskellunge also alter their detection of and approach to prey, attending to a wider region of the intact sensory hemisphere. Our data suggest not only that the visual and lateral line systems play complementary roles in the feeding behavior sequence but also that each system plays a more or less dominant role during consecutive phases of the behavior.

Animals↗

PubMed1989

Influence of acetylcholine on neuronal activity of monkey amygdala during bar press feeding behavior.

Single neuron activity in the monkey amygdala was investigated during cue signalled conditioned bar press feeding behavior and the effects of electrophoretically applied acetylcholine (ACh) and atropine were analyzed. ACh increased the firing rate of one third of the neurons tested; these excitatory responses were inhibited by the muscarinic receptor antagonist atropine. No characteristic location of ACh-sensitive neurons was found, cells were diffusely distributed throughout the amygdala. Activity of ACh-sensitive neurons did not correlate with any particular event during the bar press feeding task. However, continuous application of ACh at low current intensity during the task significantly enhanced the task-related excitatory firing patterns, or markedly attenuated the inhibitory responses. Continuous application of atropine elicited or enhanced inhibitory response patterns. These results suggest that the cholinergic system of the monkey amygdala facilitates neuronal excitation but attenuates inhibition related to various phases of feeding behavior, such as to cue recognition, food aquisition and rewarding process.

Acetylcholine↗

PubMed2000

The biologically relevant unit for the analysis of short-term feeding behavior of dairy cows.

To determine whether visits or meals are the most biologically relevant unit of short-term feeding behavior, we analyzed 209,025 records of visits to feeders by 37 cows. Two feeds were used that differed in protein content. Cows were divided into control groups for the low and high protein feeds and a choice group that had access to both. Daily number of visits and intake per visit were very variable. Cows fed low protein feed had lowest daily intakes, but single-visit characteristics were poorly correlated with daily intake. The probability of cows ending a visit did not change greatly with visit length. Log-normal models were used to estimate individual meal criteria (44.7+/-2.1 min), and visits were grouped into meals. Meal duration (36.9+/-1.3 min) and daily number of meals (6.1+/-0.1) were not affected by treatment. Feeding rate and intake per meal were lowest for cows fed low protein feed. Meal size decreased systematically during the day. The probability of cows ending and starting a meal increased with meal length and interval between meals, as predicted by the satiety concept. Meals are, therefore, a biologically relevant unit of short-term feeding behavior and visits are not.

Animal Feed↗

PubMed1990

Abnormal feeding behavior and insulin replacement in STZ-induced diabetic rats.

The present studies were undertaken to investigate whether or not decreased ambulatory activity, including abnormal feeding behavior in diabetic rats, will be simultaneously normalized by insulin administration. To do this, we used the Gunma University-type automatic apparatus for continuous and direct measurement of ambulation and drinking. In this study, 3 U NPH insulin were administered at 1800, just before the dark phase, and 2 U were administered at 0600, just before the light phase. With these insulin doses, we found that 5 weeks were needed to normalize ambulatory activity, 4 weeks were necessary for food intake, 6 weeks for drinking and 2 weeks for body weight. Since ambulatory activity is reported to be related to changes in dopamine turnover, further studies are in progress to determine whether or not dopamine turnover is normalized when there is no difference in ambulatory activity due to insulin replacement.

Animals↗

PubMed1995

ICV administration of anti-corticotropin-releasing factor antisense oligonucleotide: effects on feeding behavior and body weight.

Corticotropin-releasing factor (CRF) has been reported to reduce food intake and body weight, and numerous studies suggest a role for CRF in putative mechanisms for the regulation of body energy. This study investigated the effects of ICV-administered antisense phosphorothioate oligonucleotides, directed against the CRF mRNA, on feeding behavior and body weight in rats. Sixteen male HSD rats were cannulated in the lateral ventricle, and given ad libitum access to tap water and a ground chow diet. Feeding behavior was recorded by computer, and meal patterns were assessed. Rats were given 3 micrograms each of two anti-CRF oligonucleotides (aCRF) or two control oligos in the hour before the onset of the nocturnal cycle for ten consecutive days. Cumulative food intake was assessed at 3, 6, 12 and 24 h after each injection, as well as over the 10-day injection period. Compared to missense controls, rats receiving the antisense oligonucleotides ate significantly more at 6 h (P = 0.01), but not at 3, 12, 24 h, or during the entire 10-day injection period (P > 0.05). There was no effect on body weight change, meal size, or meal interval (P > 0.05). These data indicate that daily administration of anti-CRF oligonucleotides has a significant short-term stimulatory effect on feeding behavior, but does not have a long-term effect on feeding or body weight gain.

Animals↗

PubMed2005

Glucagon-like peptide-1, corticotropin-releasing hormone, and hypothalamic neuronal histamine interact in the leptin-signaling pathway to regulate feeding behavior.

Glucagon-like peptide-1 (GLP-1), corticotropin-releasing hormone (CRH), and hypothalamic neuronal histamine suppress food intake, a target of leptin action in the brain. This study examined the interactions of GLP-1, CRH, and histamine downstream from the leptin-signaling pathway in regulating feeding behavior. Infusion of GLP-1 into the third cerebral ventricle (i3vt) at a dose of 1 mug significantly decreased the initial 1 h cumulative food intake in rats as compared with phosphate-buffered saline (PBS) controls. The GLP-1-induced suppression of feeding was partially attenuated by intraperitoneal pretreatment with alpha-fluoromethylhistidine (FMH), a specific suicide inhibitor of histidine decarboxylase, which depletes hypothalamic neuronal histamine. Pretreatment with alpha-helical CRH (10 microg/rat, i3vt), a nonselective CRH antagonist, abolished the GLP-1-induced suppression of feeding completely. I3vt infusion of GLP-1 increased the CRH content and histamine turnover assessed using the pargyline-induced accumulation of tele-methyl histamine (t-MH), a major metabolite of neuronal histamine, in the hypothalamus. The central infusion of CRH also induced the increase of histamine turnover and CRH receptor type 1 was localized on the cell body of histamine neuron. Pretreatment with exendin(9-39), a GLP-1 receptor antagonist, attenuated the leptin-induced increase in CRH content of the hypothalamus. Finally, i3vt infusion of leptin also increased histamine turnover in the hypothalamus. Pretreatment with exendin(9-39), alpha-helical CRH or both antagonists attenuated the leptin-induced responses of t-MH levels in the hypothalamus. These results suggest that CRH or hypothalamic neuronal histamine mediates the GLP-1-induced suppression of feeding behavior, that CRH mediates GLP-1 signaling to neuronal histamine and that a functional link from GLP-1 to neuronal histamine via CRH constitutes the leptin-signaling pathway regulating feeding behavior.

Animals↗

PubMed1999

Stimulation of feeding behavior and food consumption in the goldfish, Carassius auratus, by orexin-A and orexin-B.

The neuropeptides, orexin-A and orexin-B, have been demonstrated to have a physiological role in the regulation of food intake in mammals. The effects of human orexin-A and orexin-B intracerebroventricular (i.c.v.) injection on the feeding behavior of goldfish (Carassius auratus) were investigated. I.c.v. injection of orexin-A and orexin-B both caused a significant increase in appetite, as indicated by an increased number of feeding acts. Orexin-A and orexin-B both significantly stimulated food consumption, as indicated by increased total food intake during a 60-min observation period; the actions of orexin-A were dose dependent. Orexin-A was more potent than orexin-B in stimulation of both feeding behavior and food intake. These results indicate that orexin peptides are involved in the hypothalamic regulatory pathways of feeding behavior in goldfish.

Amino Acid Sequence↗

PubMed2003

Intraruminal infusion of propionate alters feeding behavior and decreases energy intake of lactating dairy cows.

The dose-response effects of intraruminal infusion of propionate on feeding behavior of lactating dairy cows were evaluated with eight ruminally cannulated Holstein cows past peak lactation. Treatments were mixtures of propionic acid and acetic acid containing propionic acid at eight different concentrations in Experiment 1, and mixtures of sodium propionate and sodium acetate containing sodium propionate at 4 different concentrations in Experiment 2. Experimental designs were an 8 x 8 and duplicated 4 x 4 Latin squares, respectively, for Experiments 1 and 2. Treatment solutions were infused into the rumen continuously for 14 h at a rate of 16.7 and 25 mmol/min, respectively, for Experiments 1 and 2. Infusion started 2 h before feeding and ended 12 h after feeding; feeding behavior was monitored for 12 h after feeding using a computerized data acquisition system. Total metabolizable energy (ME) intake was calculated by adding the energy of infusates to dietary energy intake. In both experiments, as the proportion of propionate of the infusates increased, total ME intake and dry matter intake decreased linearly. As infusion of propionate increased, meal size tended (P < 0.09) to decrease linearly and intermeal interval tended (P < 0.07) to increase linearly in Experiment 1; meal size decreased linearly and number of meal bouts tended (P < 0.08) to decrease linearly in Experiment 2. These observations indicate that the reduction in dietary energy intake from propionate infusion was greater than the energy supplied from infusates, and that propionate plays an important role in feed intake regulation by affecting both satiety and hunger.

Animals↗

PubMed2003

State-dependent modulation of feeding behavior by proopiomelanocortin-derived beta-endorphin.

Feeding behavior can be divided into appetitive and consummatory phases, differing in neural substrates and effects of deprivation. Opioids play an important role in the appetitive aspects of feeding, but they also have acute stimulatory effects on food consumption. Because the opioid peptide beta-endorphin is co-synthesized and released with melanocortins from proopiomelanocortin (POMC) neuronal terminals, we examined the physiological role of beta-endorphin in feeding and energy homeostasis using a strain of mutant mice with a selective deficiency of beta-endorphin. Male beta-endorphin-deficient mice unexpectedly became obese with ad libitum access to rodent chow. Total body weight increased by 15% with a 50-100% increase in the mass of white fat. The mice were hyperphagic with a normal metabolic rate. Despite the absence of endogenous beta-endorphin, the mutant mice did not differ from wild-type mice in their acute feeding responses to beta-endorphin or neuropeptide Y administered intracerebroventricularly or naloxone administered intraperitoneally. Additional mice were studied using an operant behavioral paradigm to examine their acquisition of food reinforcers under increasing work demands. Food-deprived, beta-endorphin-deficient male mice emitted the same number of lever presses under a progressive ratio schedule compared to wild-type mice. However, the mutant mice worked significantly less than did the wild-type mice for food reinforcers under nondeprived conditions. Controls for nonspecific effects on acquisition of conditioned learning, activity, satiety, and resistance to extinction revealed no genotype differences, supporting our interpretation that beta-endorphin selectively affects a motivational component of reward behavior under nondeprived conditions. Therefore, we propose that beta-endorphin may function in at least two primary modes to modulate feeding. In the appetitive phase, beta-endorphin release increases the incentive value of food as a primary reinforcer. In contrast, it appears that endogenous beta-endorphin may inhibit food consumption in parallel with melanocortins and that the orexigenic properties previously ascribed to it may actually be due to other classes of endogenous opioid peptides.

Adrenocorticotropic Hormone↗

PubMed1999

Central gastrin inhibits feeding behavior and food passage in neonatal chicks.

The gastrin/cholecystokinin (CCK) family is recognized as the principal family of hormones involved in regulation of the gastrointestinal tract CCK is recognized as a satiety hormone in mammalian species, but it has been suggested that gastrin rather CCK may have an important role in controlling feeding behavior in the neonatal chick through a poorly developed blood brain barrier. So far, however, there is no direct evidence that central gastrin inhibits food intake in neonatal chicks. The aim of this study was to elucidate whether central administration of gastrin 1) inhibits feeding behavior and 2) alters food passage from the crop. The effects of central administration of gastrin on food intake were investigated in experiment 1. Birds (2-day-old) were food-deprived for 3 h and then gastrin or saline was injected intracerebroventricularly. Gastrin strongly inhibited food intake in a dose-dependent fashion for 2 h. Thereafter, the effects of central gastrin on feeding behavior and serum corticosterone concentration were examined in experiment 2. Following central administration of gastrin, food intake was depressed and pecking behavior was inhibited. Serum corticosterone concentration was not altered by central administration of gastrin. The influence of central gastrin on food passage from the crop was investigated in experiment 3. Central administration of gastrin clearly delayed food passage. In conclusion, central gastrin appears to have a strong effect for the satiety and gastrointestinal motility in the neonatal chick.

Animals↗

PubMed2006

TTF-1, a homeodomain-containing transcription factor, regulates feeding behavior in the rat hypothalamus.

TTF-1 is a member of the NKx family of homeodomain genes, and is required for morphogenesis and fetal diencephalon development. Our previous studies have shown that TTF-1 expression is maintained in some regions of the postnatal rat brain and transactivates the gene expression of several neuropeptides. In this study, a potential role for TTF-1 in the regulation of feeding behavior was identified. Immunohistochemical analysis showed that TTF-1 is present in several hypothalamic nuclei of the adult rat brain involved in the control of feeding behavior. Food deprivation for two days markedly increased the hypothalamic levels of TTF-1 mRNA and protein. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased TTF-1 protein abundance in the hypothalamus. This TTF-1 decrease was followed by a significant decrease in neuropeptide Y mRNA content and an increase in proopiomelanocortin mRNA content, and in turn resulted in a decrease of the animal's food intake and body weight. These results suggest a novel role for TTF-1 in the regulation of feeding behavior in the rat hypothalamus.

Animals↗

PubMed2006

Host plant resistance in romaine lettuce affects feeding behavior and biology of Trichoplusia ni and Spodoptera exigua (Lepidoptera: Noctuidae).

Lettuce quality and yield can be reduced by feeding of several lepidopterous pests, particularly cabbage looper, Trichoplusia ni (Hübner), and beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae). Host plant resistance to these insects is an environmentally sound adjunct to conventional chemical control. In this study we compared the survival, development, and feeding behavior of cabbage looper and beet armyworm on two romaine lettuce cultivars, resistant 'Valmaine' and susceptible 'Tall Guzmaine'. Larval mortality of both species was significantly higher on resistant Valmaine than on susceptible Tall Guzmaine. The average weight per larva after feeding for 1 wk on Tall Guzmaine plants was 6 times (beet armyworm) and 2 times (cabbage looper) greater than that of larvae feeding on Valmaine plants. Significant reduction in larval growth on Valmaine compared with that on Tall Guzmaine resulted in a 5.9- (beet armyworm) and 2.6-d (cabbage looper) increase in larval duration and almost a 1-d increase in pupal duration. Average pupal and adult weights and successful pupation of cabbage looper and beet armyworm were reduced on Valmaine compared with Tall Guzmaine. The sex ratio of progeny did not deviate from 1:1 when larvae were reared on either Valmaine or Tall Guzmaine. The fecundity of cabbage looper and beet armyworm adults that developed from larvae reared on Valmaine was about one-third that of adults from Tall Guzmaine, but adult longevity did not significantly differ on the two lettuce cultivars. The two insect species showed different feeding preferences for leaves of different age groups on Valmaine and Tall Guzmaine. Cabbage loopers cut narrow trenches on the leaf before actual feeding to block the flow of latex to the intended site of feeding. In contrast, beet armyworms did not trench. The different feeding behavior of the two species on Valmaine may explain the superior performance of cabbage looper compared with beet armyworm.

Animals↗

PubMed1994

Bombesin acts to suppress feeding behavior and alter serum growth hormone in goldfish.

The acute effects of a single injection of bombesin (BBS) on feeding behavior and serum growth hormone (GH) levels in goldfish were examined. When injected intraperitoneally (IP), BBS (0.5-100 ng/g) caused a dose-dependent decrease in food intake within 30 and 45 min of administration; maximal suppression was achieved at 50 ng/g BBS and was accompanied by an elevation in serum GH levels. Associated with IP injection of BBS was a pronounced spitting out behavior in which food pellets were taken into the oral cavity but immediately expelled. When injected into goldfish deprived of food for 72 h, 50 ng/g BBS was still potent in suppressing feeding behavior and increasing serum GH. Additionally, IP injection of BBS (10 or 100 ng/g) into groups of fish caused a significant increase in circulating serum GH levels at 1.5 h postinjection. Finally, when injected into the third brain ventricle (ICV), 60 ng/g BBS also caused a suppression in food intake and a concomitant increase in serum GH. Groups of fish injected ICV with 5 or 50 ng/g BBS also exhibited a graded increase in serum GH levels at 45 min postinjection. Overall, these data are the first to demonstrate in any lower vertebrate that a neuropeptide acts to suppress food intake and cause concomitant alterations in circulating serum GH levels, following either peripheral or central administration.

Animals↗

PubMed1988

Alpha 2-adrenoceptor blockade attenuates feeding behavior induced by neuropeptide Y and epinephrine.

Neuropeptide Y (NPY, 0.47 nmol) and epinephrine (28.9 nmol) evoked robust, and quantitatively similar, increments in food intake and local eating rate following administration into the third cerebral ventricle (IIIV). Whereas IIIV pretreatment with phentolamine (71 nmol), a nonselective alpha-adrenoceptor antagonist, or prazosin (9.5 nmol), a selective alpha 1-adrenoceptor antagonist, was without effect on NPY-induced feeding behavior, pretreatment with the alpha 2-adrenoceptor antagonist yohimbine (15 nmol) dramatically attenuated the stimulatory effects of NPY or epinephrine on both food intake (by over 50%) and local eating rate. Additionally, yohimbine administered alone was associated with a stimulatory effect on food intake for the periods of 80-110, and 110-140 minutes posttreatment. These data demonstrate that feeding behavior induced by IIIV administration of NPY or epinephrine is attenuated by prior blockade of alpha 2-adrenoceptors and suggest that, as in other systems innervated by neurons displaying NPY and adrenergic transmitter colocalization, the effects of NPY on feeding behavior may, at least in part, be mediated via alpha 2-adrenoceptors.

Adrenergic alpha-Antagonists↗

PubMed2006

Effects of season and breed on the feeding behavior of multiparous lactating sows in a tropical humid climate.

The effects of breed and season on performance and feeding behavior were studied during 76 lactations in multiparous Large White (LW; n = 17) and Creole (CR; n = 23) sows reared in a humid tropical climate. The experiment was conducted in Guadeloupe (French West Indies, latitude 16 degrees N, longitude 61 degrees W) between May 2002 and July 2004. Average daily ambient temperature was greater during the hot season than during the warm season (26.0 vs. 23.8 degrees C), but relative humidity was similar in both seasons (85% on average). The daily fluctuations of ambient temperature and relative humidity were similar for both seasons. At farrowing, BW was lower (187 vs. 265 kg) and backfat thickness was greater (40 vs. 22 mm) in CR than in LW sows (P < 0.01). Sows were offered feed ad libitum between the fifth and the 26th day of lactation. There was a breed x season interaction (P < 0.05) for ADFI. During the hot season the reduction of ADFI was more pronounced in LW than in CR sows (-1,100 vs. -300 g/d). Irrespective of breed and season, the daily number of meals was 9.0. The meal size and the rate of feed intake were greater in LW than in CR sows, respectively (555 g and 153 g/min vs. 390 g and 83 g/min; P < 0.01). The diurnal proportion of ADFI was greater in CR than in LW sows (0.60 vs. 0.41; P < 0.01). The reduction in ADFI in LW sows during the hot season was mainly related to a reduction in feed intake during the day rather than during the night (-1.3 vs. -0.2 kg; P < 0.01). Duration of standing was not affected by breed or season, and it averaged 120 min/day. This study confirms the negative effect of the hot season on feeding behavior of lactating sows. It also suggests a better acclimation to daily high temperatures and a greater heat tolerance in CR compared with LW sows, at least for eating behavior.

Animals↗